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Jones, Kate. "Monitoring, Assessment, and Management of the Green Sea Urchin (Strongylocentrotus droebachiensis) Fishery in Maine." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/JonesKX2006.pdf.
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Kling, Ashley Lindsey. "Effects of Formulated Feeds and Saccharina Latissima on Growth, Gonadal-Somatic Index, and Gonad Color in Grow-Out Stage Green Sea Urchins, Strongylocentrotus droebachiensis, in Land-Based Echiniculture." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/KlingAL2009.pdf.
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Lau, Chi Chung Dickey. "Population variability and impact of sea urchin Anthocidaris crassispina in Hong Kong." HKBU Institutional Repository, 2011. https://repository.hkbu.edu.hk/etd_ra/1298.
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Heyland, Andreas. "Thyroid hormone-like function in echinoids a modular signaling system coopted for larval development and critical for life history evolution /." Connect to this title online, 2004. http://purl.fcla.edu/fcla/etd/UFE0004542.
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Sweijd, Neville Anthony. "The digestive mechanisms of an intertidal grazer, the sea urchin Parechinus angulosus." Thesis, Rhodes University, 1991. http://hdl.handle.net/10962/d1005346.
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Echinoids are important grazers in the near-shore ecosystem and can significantly effect their ecology. The sea urchin Parechinus angulosus occurs inter- and subtidally along the southern African coast. Within this range it consumes an extremely wide variety of algae. Since algal cell walls have an almost species specific chemical composition, the question arises as to how it can digest the algae that it consumes. In order to investigate the digestive mechanisms employed by P. angulosus, an ultrastructural study of the gut was undertaken to characterize the tissue and identify functional regions in the gut. Ten structural and storage polysaccharides commonly found in macroalgae were used as substrates to assay the digestive polysaccharidases of the sea urchin. The enteric bacteria of the sea urchin were isolated and tested separately for polysaccharidase activity using the same substrates. The results shown that the gut of Parechinus angulosus is regionally specialized, with the foregut primarily responsible for the production of hydrolytic enzymes, while the hindgut is primarily absorptive. The occurrence of lamellar bodies, heterolysosomes, cytoplasmic blebs and paddle cilia among other characteristic features of the digestive epithelium are described and discussed. Two levels of enzyme activity are apparent. Generally the urchin could hydrolyze the reserve polysaccharides, but only partially hydrolyze the structural polysaccharides, of red and green algae. P.angulosus was unable to digest alginic acid, the main structural polysaccharide of brown algae. Mixed cultures of bacteria utilized only the reserve polysaccharides of red and green algae. Significantly, the bacteria were able to hydrolyze alginic acid. Enteric bacteria also showed agarolytic activity. Parechinus angulosus has the ability to digest red and green algae. No lysozyme activity was detected. The enteric bacteria can digest the same algal reserve polysaccharides and so may compete for carbon in the gut. However, in the case of brown algae, bacteria have a potentially important endosymbiotic role as agents of digestion. These results correspond with food preference studies which have shown that, although P.angulosus consumes the kelp Ecklonia maxima, in the western Cape, it is amongst its least preferred food species. The reasons for this are its unpalatability and the urchin's inability to digest brown algae. The digestibility of algal material can be an important factor in determining algal-herbivore interactions.
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Chiu, Sein-tuck. "Aspects of the ecology of Anthocidaris crassispina (echinodermata: echinoidea) in Hong Kong /." [Hong Kong : University of Hong Kong], 1987. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1233571X.
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Farquhar, Michael Robert. "Interspecific interactions of the sea urchin Parechinus angulosus and the effect of variations in microhabitat availability." Thesis, Rhodes University, 1995. http://hdl.handle.net/10962/d1005406.
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Intertidal populations of the sea urchin Parechinus angulosus were examined at seven sites along the south and east coasts of South Africa. At the five southerly sites, P. angulosus occurred in allopatry, while, at the two northerly sites, it occurred in sympatry with several species of Indopacific sea urchins. At the five southerly sites, there was a significant correlation of number of sea urchins per pool with the surface area of the overhang in that pool. This relationship broke down for P. angulosus at the two northerly sites, where there was a significant correlation between these two factors for Stomopneustes variolaris. The density of populations of P. angulosus at the two northerly sites, although not significantly different from all five southerly sites, were considerably lower. There was a significant difference between the mean size of populations at the seven sites. Although no direct evidence is available, a competitive interaction between these two species is proposed to explain the observed patterns of microhabitat utilization and densities. Two series of manipulative experiments were conducted at Kowie Point, where P. angulosus occurs in sympatry, The first, involved urchin removals from three experimental sites. The percentage cover of four functional algal groups was monitored in three experimental and three unaltered control sites over a three month period in spring (Sept. - Dec.) 1993. Two 100 point 0,25m² random point quadrats were thrown at each of the six sites at approximately monthly intervals over the experimental period. Since initial cover of algae varied at the six sites, ANOVA's of the change in percentage cover of four functional algal groups were used to determine treatment effects. No treatment effects were identified for any of the four functional algal groups. There was a strong negative correlation between the percentage cover of foliose algae and encrusting coralline algae, suggesting the possibility of a competitive relationship between them. The second, involved the experimental manipulation of microhabitat availability. The blocking of overhangs, by means of cement filled bags, resulted in an approximate 50% decrease in the total number of urchins in the two experimental pools, and the two control pools without overhangs. However, in the control pool with overhangs there was a slight increase in the number of urchins over the same period. Clearly, the presence of suitable shelters, is a prerequisite for the maintenance of dense intertidal population of P. angulosus. It is proposed that, due to the exposed nature of the South African coast, intertidal populations of P.angulosus are restricted to inhabiting suitable shelters from which they emerge to feed on passing drift algae. The implications of these findings are discussed in terms of current ecological literature.
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Tauchman, Eric Gary. "Effects of ultraviolet radiation on developing variegated sea urchins, lytechinus variegatus." [Pensacola, Fla.] : University of West Florida, 2008. http://purl.fcla.edu/fcla/etd/WFE0000142.
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Olquín, Irma. "Speciation in marine systems : the case study of the sea urchin Arbacia incisa (Agassiz 1863) /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Thesis (Ph. D.)--San Diego State University, and University of California, Davis, 2003.Includes bibliographical references (leaves 65-72). Also available via the World Wide Web. (Restricted to UC campuses)
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Cowart, Dominique Alexandria. "Salinity sensitivity of embryos of the Antarctic sea urchin, Sterechinus neumayeri." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 47 p, 2008. http://proquest.umi.com/pqdweb?did=1597631011&sid=37&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Pisut, Daniel P. (Daniel Peter). "The distance chemosensory behavior of the sea urchin Lytechinus variegatus." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5129.
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Many organisms that lack vision rely on chemical signals to glean information from their environment. Little is known, however, about the ability of sea urchins to detect and respond to such signals. This lack of understanding is especially surprising given the ecological impact of urchins in their respective communities. Regardless of geography, urchins exert strong top down control of plants, algae, and sedentary invertebrates, and these effects are especially evident when urchins, or urchin predators, are removed from an ecosystem. Facultative omnivorous species such as Lytechinus variegatus may greatly alter the abundances of other invertebrates in seagrass communities by preying on juvenile and adult bivalves as well as gastropod egg masses. These potential food resources, however, are patchily distributed within seagrass beds. To find such resources before other organisms can exploit them may require acute abilities to detect signals emanating from these patches.
Experiments performed in this study demonstrated a consistent ability of L. variegatus to detect and orient to chemicals emanating from potential food resources over a distance of 1 m. Unlike what has been found in some other marine organisms, turbulent flow conditions did not negatively affect the ability of L. variegatus to find the source of this chemical cue. In fact, only the slowest flows hindered this ability; the bluff shape of the urchin formed a relatively large boundary layer at slow flows, preventing the delivery of chemical signals to the sensors. The relatively high success rates of L. variegatus in turbulent flows may allow it to effectively forage in areas where other organisms cannot. Thus, turbulence may provide a selective advantage for this animal, based on its comparative ability to detect and respond to signals in its environment.
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Husby, Kjell Runar. "Development of a Grading Machine for Sea Urchins." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produktutvikling og materialer, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22711.
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A preliminary study, conducted the fall of 2012, formed the basis for this master thesis. The thesis is issued by NTNU, and it is a part of a project in which Searis AS, Troms Kråkebolle and Norway Sea Urchins are participants. Searis AS is a start-up company, in which the student is a participant. Troms Kråkebolle and Norway Sea Urchins perform aquaculture farming, and wild catch, of sea urchins, respectively.The project was initated because of the need to automate the manual grading of sea urchins. The grading process is time consuming and increase cost for the customer. The grading involves sorting the sea urchins by their shell diameter, and removing foreign objects like stones.An iterative product development process formed the foundation for the results in this thesis. The process consited of; analysing user and customer needs and requirements, problem decomposition, development of solutions, ranking and rating, breakdown of principal solutions, tests, discussion and choice of concepts. Input for the designprocess was based on discussion with pilot customers; Troms Kråkebolle and Norway Sea Urchin, creative sessions with Searis AS, search for competitive products, computer simulations, and lab experiments.A complete system for the grading of sea urchins is proposed at principal level, and design for the for critical components of an automated grading machine is presented.The result of the thesis is a CAD?modell of a prototype of a grading machine. The CAD-modell consists of dimensions, materials, components, and assembly, and is a sketch on how a the prototype can be constructed.Experiments and simulations have strengthened the confidence in the solutions. And it is concluded that the design proposed in this thesis will be able to cover the needs for the customers.There is still parts that needs development before a complete prototype can be constructed.
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Filander, Zoleka. "Systematics and biodiversity of South African sea urchins." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/12925.
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Includes bibliographical references.The South African Echinoidea (Echinodermata) were last reviewed by Clark & Courtman Stock (1976) and numerous unidentified specimens and records have accumulated since that time, plus there have been many taxonomic changes within the group. Therefore this study, which forms the first of its kind in 37 years, aims to update knowledge on the diversity and distribution patterns of South African echinoids and to provide a user-friendly, well-illustrated guide to the group. Dry and wet specimens, particularly those within the extensive collections of the Iziko South African Museum, were morphologically examined and identified, and the associated data were added to a database. Other data considered in this study include; historic data from the South African Museum and University of Cape Town catalogues, imagery data from the EchinoMapVM open-online database, trawl by-catch data from the Department of Forestry and Fisheries, and data from published literature. These resulted in 19 new records for the region, of which 84.2% were Indo-Pacific, 5.3% introduced, and the remaining 10.5% non-endemic, raise the total number of known species to 71. All species were photographically illustrated and a field guide is presented which included synonomy and previous literature for each species, one of more photographic illustrations, a distribution map, description and notes on global distribution. In terms of biogeography the regional echinoid fauna comprises 26.8 % endemics, 1.4 % introduced, and 71.8 % non-endemics; across 14 orders and 29 families. As expected, species richness pattern increased from west to east coast. However , the east coast displayed the lowest number of records; as compared to the South coast, which had the highest. Endemism peaked on the south coast and the west and east coast both supported the same level of endemics. The only introduced species, Tetrapygus niger, was from the west coast region. In terms of depth; species richness was highest in<500m and lowest in>500m.This maybe a result of the deep-seas (>500m) being severely under-sampled. The lack of full-time taxonomists and lack of expertise to review this group, may have contributed to the high number of new records.
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Lawson, T. N. "Physical mapping of an early sea urchin gene battery from Parenchinus angulosus." Master's thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/17701.
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Bibliography: pages 95-99.The aim of this project was to characterise an early histone gene battery isolated from Parenchinus angulosus. An early histone gene battery (named H27) which was believed to have been isolated from Parenchinus angulosus, appeared by restriction enzyme mapping and partial sequencing to be identical to H22, an early histone gene battery isolated from Psammechinus miliaris. (This latter gene was obtained from M. Birnstiel.) This was further confirmed by electron microscopy, and proved to be a convenient testing ground for the electron microscopic techniques of denaturation mapping and heteroduplex anlysis. Another gene battery (named SU1) isolated fromParenchinus angulosus, was then characterised using the techniques developed whilst studying H27. The restriction enzyme map of this clone is different to that of H22, indicating that differences do indeed exist between these two early histone gene batteries. SU1 also showed the expected order of the five histone genes, as determined by hybridization against the coding regions of H22. The denaturation map of SU1 showed AT rich spacer regions and GC rich coding regions. Heteroduplex analysis indicated that the spacer regions between the Hl and H2A, the H2A and H3, and the H3 and the H2B gene coding areas are essentially nonhomologous. The H4 structural gene and corresponding spacer regions were not included in this analysis. Because it is known that all the five histones are coded for on the same strand of DNA in H22, and that each of the genes is transcribed in the same direction, it follows that, the same holds for, at least, the Hl, H2A, H3 and H2B genes of SU1.
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Bennett, Kathleen 1977. "The Complete Development of the Deep-Sea Cidaroid Urchin Cidaris blakei (Agassiz, 1878) With an Emphasis on the Hyaline Layer." Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10169.
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xv, 63 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.Living echinoids comprise two major sister clades, the Euechinoidea and the Cidaroidea. Cidaroids first appeared during the lower Permian (~255 mya) and are considered to represent the primitive form of all other living echinoids. The present study of Cidaris blakei, a deep-sea planktotrophic cidaroid urchin, provides a description of development from fertilization through early juvenile stages and is the first report of a deep-sea organism reared through metamorphosis. Cidaris blakei resembles other cidaroids in its lack of a cohesive hyaline layer, the absence of an amniotic invagination for juvenile rudiment formation, and the presence of a single spine morphotype at metamorphosis. Cidaris blakei differs from other cidaroids in the presence of an apical tuft, the extent of fenestration of postoral skeletal rods, the shape of juvenile spines and an extended (14 day) lecithotrophic stage prior to development of a complete gut. This study includes my co-authored materials.
Adviser: Alan Shanks
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Muller, Cornelius Marthinus. "The phylogeographic population structure of the Cape sea urchin, Parechinus angulosus." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/6899.
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Thesis (MSc)--Stellenbosch University, 2011.ENGLISH ABSTRACT: South Africa's coastline is in the region of 3650kms and encompasses many different and dynamic marine environments. To enhance our current understanding of the population structure and gene flow patterns of intertidal zone marine species in this region, this study sets out to investigate the phylogeographic population structure of the Cape sea urchin, Parechinus angulosus, using mitochondrial and nuclear DNA sequence data collected in 2007 and 2008. Individuals were sampled from 18 geographic locations between southern Namibia and Durban, covering nearly the full extent of the species range. Sequence data were obtained from a 790bp region of the COI mtDNA gene (n=510) and a 182bp region of the nDNA SpREJ9 gene (n=145), respectively. The mtDNA data revealed 283 polymorphic sites (36%) defining 195 haplotypes, of which 160 were unique and 35 shared among individuals. Haplotype diversity (h) was found to be high both overall (h=0.95) and for individual localities (h=0.75-0.98), with nucleotide diversity (π) being low overall (π=0.013) as well as for individual localities (π=0.0033-0.0254). AMOVA revealed significant population structure among sampling sites in the Namaqua Province biogeographical region, as well as between three of the four respective coastal biogeographic provinces/regions. Gene flow was bi-directional among sampling sites in the south coast Agulhas and East Coast Province biogeographical regions, while gene flow in the Namaqua Province appears to be dominated by northwards movement. BAPS identified a significant break in the Cape Point region, which was also reflected in the gene flow patterns and parsimony networks. This broadly corresponds to previously identified biogeographic regions as well as genetic breaks for other marine species found along this coast. Fu's Fs statistics showed strong signal(s) of population expansion for individual sampling localities as well as for the data set as a whole, while MDIV estimated a time since expansion ranging from 7733-4759 years ago. The nDNA data revealed 54 variable sites (29.7%), defining 72 alleles of which 50 were unique and 22 shared among individuals. Many of the alleles (69.4%) were restricted to single sampling sites, with Betty's Bay on the south coast being the most diverse from a genetic viewpoint. Allelic diversity was high overall (h=0.86) while nucleotide diversity was low (π=0.025). No nuclear sub-group structure was identified by BAPS, although the parsimony network revealed shallow genetic structure between the Namaqua and Agulhas Provinces, with significant pairwise ФST values also recovered between their individual coastal localities. This points to at least one major barrier to gene flow for Parechinus angulosus along the South African coast, namely Cape Point. Several additional, smaller hindrances to gene flow along the coast were also identified, most of which are congruent with findings from studies on both other and sea urchin species. As a standalone study this research elucidated many aspects regarding the phylogeography of the Cape sea urchin, P. angulosus. However, it is when viewed in the broader context of invertebrate phylogeography along the southern African coastline that this research will provide its most critical insight.
AFRIKAANSE OPSOMMING: Geen opsomming
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Egana, Ana Luisa. "Analysis of the centrosome during sea urchin oogenesis and the characterization of sphedgehog expression and function during sea urchin embryogenesis /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2000.
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Thesis (Ph.D.)--Tufts University, 2000.Adviser: Susan G. Ernst. Submitted to the Dept. of Biology. Includes bibliographical references (leaves 91-118). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Carboni, Stefano. "Research and development of hatchery techniques to optimise juvenile production of the edible sea urchin, Paracentrotus lividus." Thesis, University of Stirling, 2013. http://hdl.handle.net/1893/13178.
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Research and development in aquaculture has supported the knowledge-based development of the sector over the last decades. In particular, species diversification is playing an important role to ensure sustainability of the industry and helping to reduce pressure on wild stocks of those aquatic species for which farming technology is still at the early stages. Due to the increasing pressures on more traditional carnivorous marine finfish species (aquafeed reliance on fishmeal and fish oil, environmental impact, market price) low trophic organisms are receiving more attention to provide sustainable alternatives and integrate production activities with the aim of reducing environmental impacts and to provide secondary high value crops. Integrated Multi-Trophic Aquaculture (IMTA) systems are therefore at the forefront of innovation in the industry. Several invertebrate species have been investigated and tested as integral part of IMTA (mussels, oysters, abalone and macroalgae) and echinoderms have also been considered as good candidates for the future development of this technology. In order to allow for a more widespread uptake of integrated aquaculture, several technical and biological challenges need to be overcome, including a reliable supply of juveniles. In recent years, this has prompted investigation on Echiniculture as a whole and on hatchery technologies in particular. This PhD investigated key constraints in edible sea urchin (Paracentrotus lividus) juvenile production with the aim to improve commercial sea urchin hatchery outputs. The research firstly focused on larval nutrition (Chapter 3 and 4) and specifically tested the hypothesis that larvae required higher dietary inputs of long chain fatty acids than those provided by Dunaliella tertiolecta, a microalgae species widely used in echinoderm larval rearing. Fatty acid composition of P. lividus eggs, investigated in Chapter 3, supported this hypothesis, which was further confirmed by the results obtained in Chapter 4 where microalgae (Cricosphaera elongata, Pleurochrisis carterae and Tetraselmis suecica) with a more balanced fatty acid profile, in particular richer in long chain fatty acids, were employed. This resulted in a significantly improved larval development and survival. Results also indicated that these alternative microalgae species could be successfully grown without modification of the microalgae production protocols in the hatchery where the experimentation had taken place. The third experimental chapter compared static and flow through systems which provides more stable water quality through constant water exchange and reduces larval handling and associated stress. Results indicated that larval survival was significantly improved by the flow-through system and the need for tank cleaning was reduced (three versus seven times per larval cycle when using flow-through and static rearing systems respectively). However, water quality, based on the parameters assessed (NH4, PO4-3, NO2 and NO3), did not show any significant differences between systems. Reduced handling could have therefore played the most important role in promoting larval survival. Both these trials resulted in a significant 5 to 20 % increased survival. A follow-up study, combining flow-through with more suitable microalgae, should be carried out and could result in even further enhanced survival. Then, chapters 6 and 7 focused on broodstock nutrition and subsequent improvement of gamete quantity and quality. These two trials aimed to explore and describe the biological effects that some important nutrients, such as proteins, lipids, fatty acids and carotenoids, have on urchins’ somatic and gonadal growth, gonad biochemical composition during gametogenesis, fecundity and maternal provisioning to developing embryos. Results from the experiment described in Chapter 6 indicated that higher protein content can improve somatic growth in P. lividus adults and that more expensive, protein-, lipid- and energy-rich diets do not significantly enhance fecundity or offspring performance. Results, moreover, highlighted the need for a specifically formulated broodstock diet and gave some insights into what its composition should be, especially in relation to carotenoids. In Chapter 7, fatty acid profiles of P. lividus gonads throughout gametogenesis were studied for the first time. It was observed that, among Long Chain Polyunsaturated Fatty Acids (LC-PUFAs), Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) are primarily accumulated during gametogenesis, whilst Arachidonic acid (ARA) appears to be independent of dietary input. In addition, it was clearly shown that ARA is the only LC-PUFA accumulated in the eggs along with Non Methylene Interrupted Fatty Acids (NMI FAs). As well as looking at the biological effects of different diets on fatty acid profiles of gonadal and larval tissues, the work also expanded on a more fundamental level to explore the metabolic pathway through which precursors could be used by sea urchins for the endogenous production of long chain fatty acids (Chapter 8). Three Expressed Sequence Tags (ESTs) for putative fatty acyl desaturases, one of which was closely related to Octopus vulgaris ∆5-like fatty acyl desaturase, were identified. The newly cloned putative desaturase of P. lividus possessed all typical features of other fatty acyl desaturases. However, because of time constraints, functional characterisation, originally planned, of the new protein could not be performed and further research effort is needed to investigate this important aspect of sea urchin physiology. Overall, the aim of this research project has been achieved as it provided a set of exploitable results and protocols to improve hatchery practices for the production of P. lividus juvenile. However, more research is required to investigate some of the underlying mechanisms behind the observed biological effects such as delay in larval development when T. suecica was used as larval feed, increased broodstock fecundity, improved larval survival in the flow-through system and higher gonadal concentration of some fatty acids (mainly DHA) than provided in the feed.
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Younglao, Deborah. "Spawning, aggregation and recruitment in the black sea urchin Diadema antillarum." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64064.
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Swanson, Rebecca School of Biological Earth & Environmental Sciences UNSW. "Histamine ??? a naturally occurring settlement cue for larvae of the Australian sea urchin Holopneustes purpurascens." Awarded by:University of New South Wales. School of Biological, Earth and Environmental Sciences, 2006. http://handle.unsw.edu.au/1959.4/27240.
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The importance of chemical cues in triggering the settlement of marine invertebrate larvae has long been recognised but very few such cues have been definitively identified. Larvae of the Australian sea urchin Holopneustes purpurascens, which lives enmeshed in the fronds of macroalgae, are induced to settle by a water-soluble cue produced by the host alga Delisea pulchra. This cue was previously identified as a floridoside-isethionic acid complex. I present evidence in this thesis which supports histamine as the true settlement cue for larval H. purpurascens. The settlement cue was isolated from the polar extract of D. pulchra by bioassay-guided cation-exchange chromatography and identified as histamine using nuclear magnetic resonance spectroscopy. Algal derived and synthetic histamine at ~5 ??M induced rapid settlement in 80???100 % of larval H. purpurascens. In the first study of its kind for any marine invertebrate, variation in the distribution of new recruits was compared with quantitative variation in the distribution of histamine in the habitat. More than 90 % of new recruits were found on either the foliose red alga D. pulchra or on coralline turf algae. These algae induced >90 % settlement of larvae in laboratory assays after 24 h. D. pulchra contained far higher levels of histamine than all other algae, however, the coralline algae lacked measurable histamine. Seawater collected in situ adjacent to D. pulchra induced up to 16 % settlement of older larvae and contained the highest concentration of histamine (~5 nM). With the exception of coralline algae, variation in settlement and recruitment was consistent with the variation among species histamine contents. Initial results supported a biofilm derived settlement cue from coralline algae. I also showed that older H. purpurascens larvae settle in response to lower concentrations of histamine than younger larvae and required less exposure to histamine (10 ??M) in order to initiate irreversible metamorphosis. Histamine induced settlement of two other echinoids with non-feeding larvae. Histamine did not induce settlement of feeding larvae of two echinoids or settlement of non-feeding larvae of asteroids. Histamine may be a general settlement cue for echinoids with direct development.
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Vrable, David Joseph. "A recombinant GST-EMBP440 fusion protein from sea urchin embryos that has myosin binding capabilities /." Connect to online version, 1997. http://hdl.handle.net/1989/3741.
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Szulgit, Greg Karl. "Mechanical investigations of the mutable collagenous tissues of the echinoderms, Eucidaris tribuloides, Cucumaria frondosa, and Parastichopus parvimensis /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9823697.
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Cunningham, John Alexander. "The evolution of developmental strategy in cretaceous spatangoid sea urchins." Thesis, University of Liverpool, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511069.
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Gong, Zhiyuan. "Regulation of tubulin gene expression in sea urchin embryos." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74267.
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Regulation of tubulin gene expression in embryos of the sea urchin Lytechinus pictus has been experimentally investigated by use of cloned recombinant tubulin DNA and anti-tubulin antiserum. Tubulin synthesis appears to be autogenously regulated at the level of tubulin mRNA stability by the level of unpolymerized tubulin; i.e., the more unpolymerized tubulin, the less stable the tubulin mRNA. Destabilization of tubulin mRNA requires continued protein synthesis. Most of tubulin stored in eggs is unpolymerized; during embryogenesis the mass of tubulin per embryo changes little, but unpolymerized tubulin is increasingly polymerized into microtubules. There is a transcriptional stimulation of tubulin genes at the time of ciliogenesis but thereafter autoregulation by the ontogenetic decrease of the level of unpolymerized tubulin plays a predominant role for an increasing accumulation of tubulin mRNA. Deciliation results in a transient enhancement of transcription of tubulin genes, which is independent of the level of unpolymerized tubulin and does not require protein synthesis.
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Conlon, Ronald A. "Underexpression of paternal genes in sea urchin interspecies hybrid embryos." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63341.
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Pelikan, Kellie C. "The Effects of Petroleum Pollutants on Sea Urchins Reproduction and Development." NSUWorks, 2015. http://nsuworks.nova.edu/occ_stuetd/401.
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Disturbances, such as mass pollution events, threaten the health of vulnerable ecosystems. Recent media attention has focused on the devastating mass oil spills, but daily petroleum input from recreational and commercial ship bilge release has been overlooked. The focus of this study was the effect of petroleum products found in bilge water on fertilization success and larval viability of two sea urchin species, Lytechinus variegatus and Eucidaris tribuloides. Unlike other pollutant studies that have focused on sperm characteristics and concentrations, I chose to examine how egg integrity was compromised by petroleum products. Scanning electron microscopy revealed eggs were degraded when exposed to low levels of these pollutants. Of the three, oil was the most detrimental to Lytechinus variegatus fertilization, while gas was highly detrimental to Eucidaris tribuloides. Dosing the eggs for only two hours before introducing sperm demonstrated significant reduction in fertilization and larval survivorship. These data suggest that even relatively low and brief exposure to petroleum pollutants can have devastating effects on sea urchin reproductive success. New regulations may need to be considered when determining the safe petroleum concentration in bilge discharge.
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Baron-Taltre, Benjamin. "The Rise and Fall of the Maine Sea Urchin Industry: A Failure of Management and Institutions?" Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/Baron-TaltreBX2005.pdf.
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Duerr, Heike Edith. "Molecular characterisation of neuropeptides in echinoderms." Thesis, Royal Holloway, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314294.
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Sardhalia, Vaskar. "Calcium carbonate-naphthoquinone hybrid pigments inspired by biomineral coloration in sea urchins." Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS644.pdf.
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Les couleurs vives observées dans les biominéraux provenant d'oursins adultes, allant du violet au vert, sont attribuées à la présence de molécules de naphtoquinone polyhydroxylée (PHNQs). Ces PHNQs sont intégrés dans la calcite, probablement au cours de la croissance cristalline, se produisant via l'intermédiaire de précurseurs de carbonate de calcium amorphe (ACC). La formation de minéraux chez les oursins s'accompagne de changements de couleur dépendant du stade de minéralisation. Le spinochrome A, par exemple, présente une couleur rouge lorsqu'il est extrait des épines violettes de Paracentrotus lividus en conditions acides, ce qui indique un lien potentiel entre le pH et les variations de couleur telles qu'observées dans la formation de CaCO3. Pour avoir une meilleure compréhension de ces variations de couleur et de l'impact des naphtoquinones sur la cristallisation de l'ACC, nous avons effectué une précipitation de CaCO3 en présence de PHNQs (extraits d'épines d'oursins) et de naphtoquinones naturelles disponibles dans le commerce (naphthazarine, lawsone et juglone). Nous avons contrôlé le pH tout au long de la formation de l'ACC coloré et de sa cristallisation en calcite. Différentes techniques analytiques, dont la DSC/ATG, l’XPS, l’analyse PDF, la spectroscopie UV-Vis, le STEM-EELS, la spectroscopie RMN en phase solide et la DRX HR, ont été utilisées pour caractériser les propriétés des pigments hybrides amorphes et cristallins. Nos résultats révèlent que différents pigments peuvent créer un spectre de calcite colorée. Par exemple, la naphtazarine, rouge à un pH acide, puis bleue avant la précipitation de l'ACC, donne finalement une calcite bleue lavande, en raison d’une déprotonation/protonation successive des OH. L'effet de l'augmentation de la concentration de naphtaline sur la stabilité de l'ACC face à la cristallisation en solution et à l'air suit des tendances différentes sans affecter la structure locale de l'ACC. La quantification de la naphtaline associée à l'ACC et à la calcite révèle que seule une infime partie de la naphtaline associée à l'ACC est incorporée dans la calcite, et ce sous la forme de nano-inclusions non homogènes ; tandis que le reste est adsorbé à la surface sous l'effet de fortes forces chimiques ou physiques. En outre, le spinochrome A conduit à l’obtention de calcite violette, tandis que les spinochromes B et E à de la calcite jaunâtre. L'analyse DRX HR indique que les spinochromes B et E induisent des distorsions plus importantes dans le réseau de la calcite que le spinochrome A. De plus, le spinochrome A augmente la stabilité du polymorphe intermédiaire, modifiant ainsi la voie de cristallisation. La combinaison d'effets structurels atomiques minimes et d'une coloration intense suggère une incorporation préférentielle du spinochrome A dans les épines pourpres de P. lividus. Les PHNQs extraits des épines d'oursins et les pigments hybrides ont été testés pour la teinture des textiles, montrant des résultats prometteurs dans le cas des PHNQs biogéniques et des pigments hybrides à base d'ACCThe vibrant colors seen in adult sea urchin biominerals, ranging from purple to green, are attributed to the presence of polyhydroxylated naphthoquinone molecules (PHNQs). These PHNQs become integrated into calcite, likely during the crystal growth, which occurs through amorphous calcium carbonate (ACC) precursors. The mineral formation in sea urchins is accompanied by color changes depending upon the stage of mineralization. Spinochrome A, for example, exhibits a red color when extracted from the purple spines of Paracentrotus lividus in acidic conditions, indicating a potential link between pH and color variations, as observed in CaCO3 formation. To delve deeper into color variations and the impact of naphthoquinones on ACC crystallization, we performed CaCO3 precipitation in the presence of PHNQs (extracted from sea urchin spines) and commercially available natural naphthoquinones (naphthazarin, lawsone, and juglone). We monitored pH levels throughout the formation of colored ACC and its crystallization into calcite. Various analytical techniques, including DSC/TGA, XPS, PDF analysis, UV-Vis, STEM-EELS, ss-NMR spectroscopy, and HR-XRD, were employed to characterize the properties of the amorphous and crystalline hybrid pigments. Our results reveal that different pigments can create a spectrum of colored calcite. For instance, naphthazarin, transitioning from red at acidic pH, turns medium blue before ACC precipitation, culminating in lavender blue calcite due to successive O-H deprotonation/protonation. The effect of increasing naphthazarin concentration on ACC's stability against crystallization in solution and air followed different trends without affecting the local structure of the ACC. Quantification of naphthazarin associated with ACC and calcite revealed that only a tiny fraction of naphthazarin associated with ACC gets incorporated within the calcite in the form of non-homogeneous nano inclusions; the rest was adsorbed on the surface with strong chemical or physical forces. Furthermore, spinochrome A yields purple calcite, while spinochrome B and E produce yellowish calcite. HR-XRD analysis indicates that spinochrome B and E induce more significant distortions in calcite lattice than spinochrome A. Moreover, spinochrome A increased the stability of the intermediate polymorph, thus modifying the crystallization pathway. The combination of minimal atomic structural effects and intense coloring suggests a preference for incorporating spinochrome A in the purple spines of P. lividus. The PHNQs extracted from sea urchin spines and hybrid pigment were tested for textile dyeing, showcasing promising results in the case of biogenic PHNQs and ACC-based hybrid pigments
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Miner, Benjamin G. "Evolution of phenotypic plasticity insights from echinoid larvae /." Connect to this title online, 2003. http://purl.fcla.edu/fcla/etd/UFE0001450.
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Montpetit, Isabelle. "Localization and characterization of an ectodermal protein of sea urchin embryos." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59519.
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In the urchin Strongylocentrotus purpuratus, the expression of the Spec3 gene is associated with the growth of cilia, one of the first morphogenetic events during development. The product of this gene was characterized using an antiserum raised against a peptide corresponding to the predicted amino-terminal portion of the protein. This thesis describes the localization of the Spec3 protein at different stages during embryonic development. Immunocytochemistry indicated that the protein is associated with cilia and Golgi complexes of ectodermal cells. Agents that inhibit protein synthesis and Golgi secretion also altered its normal distribution. Fractionation of cilia and immunoblotting indicate that the protein is associated with the ciliary axoneme and that it behaves as a large aggregate.
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Riedemann, Johann. "Functional analysis and recombinant expression of a sea urchin G-string binding factor." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52277.
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Part of work presented in this thesis has been published: Regulation of gene expressions by GC-rich DNA cis-elements / J.P. Hapgood, J. Riedemann and S.D. Scherer in Cell biology international, vol. 25, 2001.Thesis (MSc)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: The sea urchin G-string binding factor 1 (suGF1) has previously been shown to bind with high affinity and selectivity to stretches of contiguous deoxyguanosine residues, a DNA motif found in the upstream regions of many unrelated genes from several organisms. It has been proposed that suGF1 plays a role in transcriptional regulation. Homopurine.homopyrimidine stretches have been shown to form unusual DNA structures, in vitro. To investigate the potential of the suGF1 binding site to form unusual structures under certain conditions, synthetic oligodeoxyribonucleotides containing the suGF1 poly(dG).(dC) binding site were subjected to circular dichroism (CD) analyses. The CD results indicate that the suGF1 binding site forms a mixture of unusual DNA structures, as deduced by comparison with the spectra obtained for B-DNA, triplex and quadruplex conformations. These results are consistent with the hypothesis that suGF1 specifically recognises G-strings that exhibit unusual structures. Exhaustive database searches showed that suGF1 has no significant homology with any previously identified proteins or cDNAs from any species. Given the relevance of mammalian models to medical science, and since no sea urchin cell lines are currently available, the identification of a mammalian functional homologue would facilitate determination of the in vivo function of such a potentially important, putative, novel DNAbinding protein in mammalian cell lines. In this study sequence analysis tools were used to identify hORFX, a putative human functional homologue of suGF1. Similarities in the domain organisation of the two proteins, prompted an investigation into the DNA-binding properties of hORFX, as well as a more detailed structure prediction analysis, with a view to determining whether hORFX is a functional homologue of suGF1. hORFX was successfully expressed in vitro, but lacked the ability to specifically bind G-strings. Theoretical predictions suggest that suGF1 has a DNA-binding domain belonging to a different family to that predicted for hORFX, consistent with differences in their respective DNA-binding specificities. suGF1 and hORFX were predicted to have helix-turn-helix and helix-loop-helix DNA-binding domains, respectively. Taken together the results do not support the hypothesis that hORFX is a suGF1 homologue. To date, no direct evidence for the in vivo function of suGF1 has been obtained. With a view to performing transactivation assays in the future, the expression of suGF1 in yeast was investigated in this project. An suGF1 expression construct was engineered and transformed into a protease-deficient yeast strain. Nuclear extracts were prepared and subjected to SOS-PAGE and electrophoretic mobility shift assays (EMSAs). suGF1 was shown to be successfully expressed in yeast cells and exhibited similar G-string-binding properties to that of native and in vitro transcribed and translated (IVT) suGF1. The suGF1 eDNA was also subjected to in si/ico expression, which together with the SDSPAGE results of yeast nuclear extracts and IVT suGF1, indicated that the protein might be expressed as multiple truncated products, due to the utilisation of multiple AUG translation start sites. These in vitro results are crucial for the ultimate outcome and correct interpretation of future transactivation experiments and lay the foundation for further investigation into the possible role of suGF1 in transcriptional regulation.
AFRIKAANSE OPSOMMING: In die verlede is bewys dat die seepampoentjie G-string-bindende faktor (suGF1) hoë affiniteit en spesifisiteit vir aaneenlopende volgordes van deoksiguanosien residue besit. Hierdie DNA motief kom algemeen voor in die stroom-op gebiede van verskeie gene in verskillende organismes. Daar is 'n veronderstelling dat suGF1 betrokke is by die regulering van geenuitdrukking. Vroeër is bewys dat homopurien.homopirimidien-ryke areas die vermoë besit om in vitro ongewone DNA-strukture te vorm. Die potentiaal van die suGF1-bindingsetel om ongewone DNA-strukture te vorm is gevolglik deur sirkulêre dikroïsme (SD) analise ondersoek. Vergelyking van die spektra vir B-DNA-, tripleks- en kwadrupleks-strukture met dié van die suGF1-bindingsetel, toon duidelik dat laasgenoemde 'n mengsel van ongewone DNA konformasies, onder die spesifieke eksperimentele omstandigehede, aanneem. Deeglike inspeksie van die beskikbare geen- en proteïendatabasisse vir alle spesies het aangetoon dat suGF1 geen merkbare kDNA- of proteïenhomoloë besit nie. As gevolg van die belang van soogdiermodelsisteme in die mediese wetenskappe, asook die onbeskikbaarheid van seepampoentjie-sellyne, is 'n soektog na 'n funktionele suGF1 homoloog in soogdiere geloods. Die ontdekking van só 'n homoloog sal dit moontlik maak om die rol van hierdie potensiaal belangrike en unieke DNA-bindingsproteïen te ondersoek. Tydens hierdie soektog is spesiale analise-programme gebruik en 'n potensiële menshomoloog van suGF1, hORFX, is geïdentifiseer. Die mees prominente ooreenkoms tussen die twee proteïene is die soortgelyke rangskikking van funksionele motiewe. Gevolglik is die DNA-bindings eienskappe van die hORFX-proteïen ondersoek, insluitende 'n detaileerde struktuur-funksie-voorspelling ten einde vas te stel of dit wél 'n homoloog van suGF1 is. hORFX is suksesvol uitgedruk in vitro, maar besit nie die vermoë om dieselfde G-string waaraan suGF1 spesifiek bind te herken nie. Teoretiese analise het voorspel dat suGF1 en hORFX aan verskillende DNA-bindings proteïen-families behoort, aangesien suGF1 'n heliks-draai-heliks en hORFX 'n heliks-lus-heliks motief bevat. Hierdie inligting, tesame met die eksperimentele resultate, dui aan dat hORFX nie 'n homoloog van suGF1 is nie. Tot op hede is daar niks bekend aangaande suGF1 se funksie in vivo nie. Met die oog op transaktiveringseksperimente in die toekoms, is die ekspressie van suGF1 in gisselle tydens hierdie navorsingsprojek ondersoek. 'n suGF1 ekspressievektor is berei en gebruik om 'n protease-negatiewe gissellyn te transformeer. Kernekstrakte is ondersoek deur SDS-PAGE en elektroforetiese mobiliteitsessais. Daar is gevind dat suGF1 suksesvol uitgedruk is in die gisselle. Die rekombinante suGF1 besit G-volgorde bindingsaktiwiteite soortgelyk aan dié van suGF1 in kernekstrakte van seepampoentjies, asook in vitro getranskribeerde-en getransleerde suGF1. Die kDNA vir suGF1 is ook in silico uitgedruk. Tesame met die SDS-PAGE-resultate het laasgenoemde aangetoon dat die suGF1-kDNA veelvuldige AUG-kodons bevat vir die inisiasie van proteïentranslasie. Dit lei moontlik tot die translasie van 'n reeks proteïenprodukte wat verkort is aan die N-terminale kant, afgesien van die volledige suGF1-proteïen. Die in vitro resultate in geheel is essensieel vir die toekomstige uitvoering en interpretasie van transaktiveringseksperimente. Hierdie projek lê gevolglik die fondasie vir 'n verdere ondersoek na die rol van suGF1 in die regulering van geenuitdrukking.
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Cole, Russell Gavin. "Distributional relationships among subtidal algae, sea urchins and reef fish in northeastern New Zealand." Thesis, University of Auckland, 1993. http://hdl.handle.net/2292/1912.
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Interactions among large brown macroalgae, sea urchins, and fishes were investigated in northeastern New Zealand during the period 1988 - 1993. The Cape Rodney to Okakari Point Marine Reserve was the site of many of these investigations. The patterns of abundance of large brown macroalgae and urchins down depth gradients over a wide geographic range were compared with those reported from earlier studies, and 3 major trends were identified. First, the fucoid alga Carpophyllum flexuosum now occurs at many sites which are exposed to wave action, in contrast to earlier studies. This alga occurred most abundantly on urchin-grazed coralline flat areas. Second, at four sites in the Marine Reserve, the densities of the echinometrid urchin Evechinus chloroticus decreased with increasing depth, rather than reaching maximal densities at mid-depths, as had previously been described. Finally, at sites of decreased exposure to wave action, the coralline flats habitat did not occur at all, and dense stands of. C. flexuosum occurred, in conjunction with the ubiquitous laminarian alga, Ecklonia radiata. Following the discovery of this new algal component to exposed rocky reefs, a more detailed study of its population characteristics was initiated. The population size structure of C. flexuosum on coralline flat areas was markedly different from that of the same species in sites sheltered from wave action. These differences occurred at both offshore islands and sites near Leigh, suggesting that it was a general pattern. C. flexuosum plants on coralline flats were smaller than those from sheltered sites, and had a greater number of smaller laminae, heavier stipes, and a greater degree of branching. There was some evidence of temporal change in the morphology of C. flexuosum from coralline flats. Comparisons between a site with C. flexuosum and a site with coralline flats suggested that the activity of fish was 75% lower in the vegetated than in the unvegetated site, and the feeding rate in the vegetated site was less than 50% that in the unvegetated site. I speculate that future effects on fish activity of the invasion of C. flexuosum into a habitat which previously lacked macroalgal vegetation may depend on changes in the morphology of plants. An investigation of many aspects of the biology of E. chloroticus in different habitats was undertaken. Analysis of the body dimensions of E. chloroticus suggested that this species was relatively tall compared to other echinometrids (average ratio of test height: test diameter = 0.54), Comparisons among habitats with differing amounts of vegetation revealed only small differences in the relationship between test diameter and test height. Small E. chloroticus (<40 mm test diameter) lived in crevices, while larger individuals grazed freely over the substratum. In vegetated habitats, the crevice-dwelling habit was maintained at test diameters about l0 mm greater than in unvegetated habitats. Very small (<20 mm test diameter) E. chloroticus frequently covered themselves with shell. Population size structures of E. chloroticus within the Cape Rodney to Okakari Point Marine Reserve were bimodal; other localities had unimodal populations. Modal sizes varied among localities, with smallest modes (50-60 mm TD) being found at Inner Hauraki Gulf sites, and largest modes at the offshore Mokohinau Islands (70-80 mm TD). Habitat did not predictably affect population size structure. A bimodal population structure was maintained at Waterfall Reef rock flats throughout the 5-year study period. Gonad size showed seasonal fluctuations at several sites, being greatest in summer. There were few consistent differences in gonad size between biological habitats. Gonad colour varied among sites and habitats, with orange gonads generally being more prevalent in vegetated habitats, and black gonads being represented more in unvegetated habitats. Smaller urchins had greater proportions of orange gonads, while larger urchins had greater proportions of brown and black gonads. Although highly variable among individual urchins, movement of E. chloroticus was greater at unvegetated sites (0.7 m per 5 days) than at vegetated sites (0.4 m per 5 days), in the Marine Reserve. Feeding of E. chloroticus was studied at a number of sites in the Marine Reserve. Urchins frequently consumed drift algae, particularly E. radiata. C. flexuosum was consumed at less than half the rate of other macroalgae in several laboratory feeding experiments, and was chosen least frequently in a field assay of feeding preferences among 8 species of macroalgae. Boosting densities of E. chloroticus in stands of E. radiata to 60 m-2 led to destructive grazing of plants over a 2 month period - at lower densities, the urchins dispersed. Densities of C. flexuosum were effectively unchanged when urchin densities were increased to these elevated levels. As a result of these observations I speculate that feeding preferences of E. chloroticus may have a role in allowing C. flexuosum to survive on coralline flats. In a laboratory experiment, urchins from a feeding aggregation did not graze algae at higher rates than individuals from outside aggregations. Diets of both E. radiata and C. flexuosum consistently produced similar gonad volumes in urchins held in the laboratory, although gonad volumes produced were low. A preliminary experiment suggested that C. flexuosum from exposed sites was consumed at lower rates than C. flexuosum from sites which were sheltered from wave action. These differences in palatability are mirrored in the formation of stable borders between coralline flats and C. flexuosum of the sheltered morphology, and the ability of C. flexuosum of the exposed morphology to survive in the coralline flats habitat. The fish fauna of the Cape Rodney to Okakari Point Marine Reserve was shown to be different from that of a nearby area. A number of species were more abundant within the Marine Reserve. Subsequent surveys showed that there were differences in abundances of 3 large carnivorous fishes among sites within the Marine Reserve, and that population size structure and the distance within which divers could approach one species, (Pagrus auratus), clearly varied between areas within the Marine Reserve. Mean standard length of P. auratus in the central marine reserve was 40% larger than that of P. auratus outside the central marine reserve, and the average minimum approach distance was 70% less in the central marine reserve. Feeding of fish by humans in the central part of the Marine Reserve was suggested to be the main cause of the differences in responses to divers. Population size structure of, and crevice occupancy by, E. chloroticus, clearly differed between the Marine Reserve and an adjacent area, with bimodal population size structures and a 10 mm greater size of crevice occupancy occurring in the Marine Reserve. The implications of these findings for extrapolating from experiments done in one area to other areas are discussed. The major biological components of rocky reef habitats identified in this study were broadly similar to those identified in previous studies in northeastern New Zealand, and have parallels in overseas studies. Long term changes to the flora of rocky reefs in northeastern New Zealand have occurred, and appear to persist by a mechanism which had previously been discounted. Similar processes to those observed in overseas studies appear to maintain habitats (consistent recruitment of algae or urchins to habitats which they dominate), or cause them to change from one habitat state to another (e.g. grazing outbreaks by urchins). However, the predictability of the persistence of these habitats at a particular site appears to be low. Further, the precise mechanisms whereby habitats may change from one to another may also be unpredictable. I argue that there is little scope for general statements concerning the spatial and temporal occurrence, or mode, of habitat transitions on temperate subtidal reefs. This study emphasises the value of repeated descriptions of patterns of abundance, and highlights problems of extrapolation and generalisation in marine ecology. Insufficient information exists at present to comment adequately on the persistence of subtidal habitat types. This may in part stem from the types of information which have been collected in the past. Methodological problems with the use of quadrats to sample densities of organisms in areas of differing topography are therefore addressed. In conclusion, it is suggested that sampling protocols which incorporate a variety of information, gathered over as wide an area, and as intensively as possible, should be used in future research of this type.
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Harianto, Januar. "Physiological response of adult and juvenile sea urchins (Heliocidaris erythrogramma) to warming and acidification." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/20420.
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Approximately 25 % to 40 % of anthropogenic carbon dioxide (CO2) emissions have been absorbed by the oceans, influencing the physical and chemical properties of seawater and contributing to ocean warming (OW) and acidification (OA). This thesis investigated the impact of long-term exposure to OW and OA, at levels predicted for up to the years 2050 and 2100 on the physiological responses of the sea urchin, Heliocidaris erythrogramma. This species is an ecologically important benthic ecosystem engineer in south-east Australia with the ability to reshape community assemblages through its herbivory. Experimental studies on adult H. erythrogramma were conducted using experimental designs which involved a gradual introduction to future OW and OA conditions, long-term incubation periods to accommodate acclimatory responses and temperature adjustments over time to incorporate seasonal change. The influence of parental acclimation effects on offspring responses to OW and OA were also investigated to determine the potential for transgenerational effects. Temperature is the most important factor in determining the performance and fitness of marine ectotherms. In the southeast Australian OW hotspot, up to +6 °C of warming is projected for the region by the year 2100. The consequences of exposure to warming were investigated in H. erythrogramma in experiments that employed gradual adjustment over 6 weeks to four temperature levels (ambient 20 °C, 22 °C, 24 °C, 26 °C). This was followed by an acclimation period of 3 months at these temperatures in constant conditions. Metabolic rate, Q10, heat-shock protein (HSP70) expression, gonad index, gonad histology and survival were measured. There were no significant effects of elevated temperature on metabolic rate, HSP70 protein expression and survival at 22 °C, indicating that H. erythrogramma was able to tolerate a +2 °C increase in temperature. However, metabolic depression was evident at the highest warming level of +6 °C (26 °C) which caused decreased survival and elevated HSP70 protein expression. Heliocidaris erythrogramma responded to the stress of increased temperature by altering its physiology, but long-term exposure to +4 °C and +6 °C levels of warming incurred unsustainable metabolic costs and led to trade-offs between metabolism, HSP70 expression and survival. Decreased pH through uptake of CO2 affects a wide range of physiological functions in sea urchins due to alteration of the carbonate chemistry of seawater which affects pH balance, mineral saturation for skeletogenesis and physiological hypercapnia (CO2). The thermal and metabolic responses of H. erythrogramma are likely to be influenced by OA, with the combined impact of OW and OA being difficult to predict. To investigate the effects of both stressors on the physiology of H. erythrogramma, OA was incorporated with OW in a multistressor experimental design. Heliocidaris erythrogramma collected in winter were gradually adjusted over 7 weeks to three temperature (ambient, +2 °C and +3 °C) and two pH (ambient 8.0, low 7.6) treatments. Temperature was adjusted weekly to reflect the seasonal temperature change that occurs over time from winter to summer (17 °C to 22 °C). The elevated temperature treatments were adjusted to offset the temperature profile. The sea urchins were incubated in those conditions for 22 weeks. Metabolic rate was quantified at 4 and 12 weeks of acclimation and feeding and ammonia excretion rates were measured at 12 weeks. Survivorship was recorded daily for up to 22 weeks. In single stressor treatments metabolic rate increased with either OW or OA. In contrast, the two stressors interacted when combined causing a decrease in metabolism as temperature increases at low pH. There was no evidence of interaction between the two stressors for feeding rate, ammonia excretion rate, or survival. Thus, while pH influenced metabolic rate causing metabolic depression at +3 °C, there was no evidence of pH affecting the other parameters measured. Survival was significantly reduced at +3 °C, regardless of pH, but not at +2 °C. It appeared that the earlier arrival of warmer temperature in the +3 °C treatment was stressful, especially during a time of increasing gonad development. H. erythrogramma may be living close to its lethal limit in Sydney Harbour since it already experiences the temperatures used in the study. This study highlighted the importance of investigating multiple physiological traits in characterising organism responses to climate change. Current populations are likely to be vulnerable to the combined stress of OW and OA in the near future. While investigations of climate change effects at the adult stage provide insights into the resilience of established adult populations, it is also important to understand how their offspring may be affected. These transgenerational carry-over effects are influenced by a combination of parental environmental history and developmental plasticity and can convey resilience to offspring between generations. To investigate the influence of parental environment on offspring performance, adult H. erythrogramma were acclimated to OW and OA conditions over the gonad developmental period (winter to summer) and then spawned after 3 months in the adult treatments. The resulting embryos were incubated over 14 days to the juvenile stage at four temperatures (18 °C, 20 °C, 22 °C, 24 °C) and two pHT levels (8.0, 7.6). Juvenile metabolic rate and test diameter (as a proxy for growth) were measured. Parental exposure to warming had a net increased effect on the metabolic rate responses of juveniles to temperature, whereby they respired more (up to 30 %) when incubated in warmer treatments. There were no effects of parental environment or juvenile thermal environment on growth. Parental exposure to low pH had no effect on metabolic rate or growth. However, exposure to low pH during offspring development significantly affected the growth of the juveniles (up to 4 % decrease). This thesis uses metabolic rate as a key indicator of physiological response to projected climate change conditions. Metabolic rate measurements are well-established as a key parameter to assess the biological and ecological consequences of environmental stress. However, current methods of estimating metabolic rates from respirometry data are difficult and are performed manually, which introduces subjectivity to the estimates. To address problems associated with the lack of standard methods to analyse increasingly complex respirometry data, a new package for the R statistical computing language, called respR, was developed. This software package provides a range of functions for analysing respirometry data. Importantly, this package simplifies handling and analysis of respirometry data and can be used to reliably and rapidly generate reproducible analyses of metabolic rates. The respR package provides new methods to accurately detect maximum and minimum rates, linear sections of previously intractable data, and critical oxygen tension, based novel techniques of rolling regression and machine learning. The package has been published as an open-source project to address data reproducibility and transparency when processing respirometry data. For H. erythrogramma, an ecologically important species on Australia’s temperate reefs, there were clear long-term physiological consequences of acclimation to OW and OA on physiological condition and fitness. This species is vulnerable to a +3 °C increase in temperature but appears resilient to decreased pH. The response of H. erythrogramma to the combined effect of both stressors appeared to be dominated by changes in temperature. The outcomes of this research have significant implications as to the resilience of H. erythrogramma to climate warming, especially where it resides in the global warming hotspot of temperate Australia. However, there was evidence of carry-over effects on juvenile physiology shaped by parental environment, which suggests a capacity for transgenerational resilience. Further work is required to determine the multi-generational response of this species to climate change.
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Taylor, Anna M. "Effects of dietary carbohydrate on weight gain and gonad production in juvenile sea urchins, Lytechinus variegatus." Birmingham, Ala. : University of Alabama at Birmingham, 2006. http://www.mhsl.uab.edu/dt/2006m/taylor.pdf.
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Yamamori, Luna. "Ecology and adaptative evolution of gastropods and cirripeds symbiotic with sea urchins in marine rocky reefs." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263723.
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京都大学新制・課程博士
博士(人間・環境学)
甲第23262号
人博第977号
京都大学大学院人間・環境学研究科相関環境学専攻
(主査)教授 加藤 眞, 教授 市岡 孝朗, 准教授 西川 完途
学位規則第4条第1項該当
Doctor of Human and Environmental Studies
Kyoto University
DGAM
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Chiu, Sein-tuck, and 趙善德. "Aspects of the ecology of Anthocidaris crassispina (echinodermata: echinoidea) in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B31230805.
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Fabrèges, Dimitri. "Phenotypic Variations In Animal Morphogenesis : Sea Urchin Twins And Cloned Rabbits." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS010/document.
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La variabilité est une propriété intrinsèque aux systèmes biologiques, essentielle pour l'évolution et l'embryogénèse. Souvent considérée comme du bruit, ce n'est que récemment que l'aléatoire des processus biologiques a commencé à être systématiquement étudié. Cette thèse pose les questions suivantes : qu'est-ce qu'un développement normal ? Quel est l'étendue et le rôle de la variabilité dans la robustesse et la résilience du développement embryonnaire ?Ces questions sont posées pour le lapin (Oryctolagus cuniculus) et l'oursin (Paracentrotus lividus et Sphaerechinus granularis).Nous nous sommes aussi intéressé à la quantification du déterminisme de la variabilité embryonnaire à l'aide d'oursins jumeaux et de lapins clonés.La mesure des comportements cellulaires est effectuée sur des lignages cellulaires obtenus à partir d'imagerie 3D+temps. Nous montrons que les oursins jumeaux peuvent se développer selon trois phénotypes différents, jamais observés chez le normal, avant de converger vers une blastula d'apparence normale. De plus, les comparaisons entre et au sein des pairs de jumeaux montrent que le phénotype et la survie ne dépend que de l'histoire individuelle des embryos.Nos mesures quantitatives des pairs de jumeaux amènent des questions ouvrant de nouveaux horizons de recherche : les jumeaux sont-ils robustes ou résilient ?Le développement pré-implantatoire des lapins a été étudié sur cinq embryons numériques (trois sauvages et deux clones), du stade 32-cellules à l'éclosion.Nous montrons que les divisions asymétriques internes et externes régulent la variation du nombre de cellules internes ainsi que la taille de la masse cellulaire.De plus, la variation du nombre de cellules internes est plus grande que pour les cellules externes, ce qui semble directement lié au taux de morts cellulaires.Notre hypothèse est que le potentiel de bon développement des clones est assuré par une grande plasticité épigénétique des cellules donneuses.Ce travail espère définir des méthodes et des concepts fondateurs pour une exploration quantitative et une modélisation multi-échelle de la morphogénèse animaleVariability is an intrinsic characteristic of biological systems, essential for evolution and embryogenesis.Considered as noise for centuries, it is only recently that the stochasticity of biological processes has began to be systematically explored.The present thesis addresses the following questions: What is a normal development?What is the extent and role of variability in developmental robustness and resilience?We tackle these issues in rabbit (Oryctolagus cuniculus) and sea urchin (Paracentrotus lividus and Sphaerechinus granularis).We also aimed to quantify determinism and stochasticity of developmental variability by means of sea urchin twins and cloned rabbits.Variations in cell behaviors were investigated through reconstruction of cell lineage from 3D+time imaging.We showed that sea urchin twins can follow three different developmental paths never observed in normal embryo, before converging to normal looking blastula.Moreover, comparisons between and within pairs of twins revealed that phenotype and survival depend on individual history alone.Our quantitative observation of twin pairs raises question opening a future line of research: are twins robust or resilient?Rabbit preimplantation development was explored with five digital specimens (three wild-types and two clones) from the 32-cell stage to hatching.We showed that inner and outer asymmetric divisions regulate the variation of inner cell number and may control inner cell mass size.In addition, the variation of inner cell number in clones is higher than outer cells which seems to be directly correlated to their cell death ratio.Our current hypothesis is that the potential to lead to viable clones requires plasticity of donor's epigenetic state.This work is expected to ground concepts and methods for a quantitative exploration and further multilevel modeling of morphogenetic processes
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Vanderklift, Mathew Arie. "Interactions between sea urchins and macroalgae in south-western Australia : testing general predictions in a local context." University of Western Australia. School of Plant Biology, 2002. http://theses.library.uwa.edu.au/adt-WU2004.0086.
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Generalist herbivores profoundly influence the biomass and species composition of macroalgae assemblages. In subtidal ecosystems of temperate latitudes, large invertebrates are usually the most influential herbivores. I tested the prediction that exclusion of invertebrate herbivores would lead to changes in the biomass and species composition of the macroalgae assemblages that are a prominent feature of the reefs in south-western Australia. The most abundant invertebrate herbivores were sea urchins (Heliocidaris erythrogramma, Phyllacanthus irregularis and Centrostephanus tenuispinus), and these occupied different trophic positions. Heliocidaris was present at virtually all reefs surveyed, and was particularly abundant in the Fremantle region. Analyses of stable isotopes and direct observations of gut contents revealed that it was almost exclusively herbivorous, and that it mainly ate foliose brown algae. In contrast, Phyllacanthus and Centrostephanus were omnivorous; while they consumed large proportions of algae, a substantial proportion of the diet of both species was animal tissue. Because Heliocidaris is a generalist herbivore that occurs at high densities, it could exert a large influence on the macroalgae assemblage. This prediction was tested by a series of press experiments. Contrary to the prediction, Heliocidaris exerted a very minor influence on the biomass, and no detectable influence on the species composition, of attached macroalgae. However, it exerted a major influence on the retention of drift macroalgae and seagrass by trapping and feeding on drift. It exerted a particularly strong influence on retention of the kelp Ecklonia radiata. This kelp was not abundant in the attached algae assemblage (when all plots were pooled it ranked 35th in biomass), but was abundant as drift (ranking 1st). Most of the drift Ecklonia was retained by sea urchins, rather than freely drifting.Herbivorous fish may also influence macroalgae assemblages. To compare the effects of sea urchins versus fish on recruiting and adult macroalgae a 13-month exclusion experiment was conducted. There were no detectable effects of sea urchins (mainly Heliocidaris) on either recruiting or adult macroalgae. There were some patterns in the biomass of recruiting algae consistent with an influence by herbivorous fish; however, these patterns were also consistent with the presence of artefacts (shading and reduced water flow) by fish exclusion devices. I began with the prediction that large invertebrate herbivores were a major influence on the macroalgae assemblages of subtidal reefs in south-western Australia. Overall, there was little evidence to support this prediction: within spatial extents of tens of square metres and over periods of 1-2 years, only minor effects were detected. However, it remains plausible that herbivores exert an influence over long time periods across large spatial extents in south-western Australia. I propose that trophic subsidies support the comparatively high densities of Heliocidaris that exist at some reefs. I further propose that these subsidies mediate the effects of sea urchins on the attached macroalgae assemblage, and that they might play an important role in energy and nutrient cycling in these nearshore ecosystems.
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Hereu, Fina Bernat. "Role of trophic interactions between fishes, sea urchins and algae in the northwestern Mediterranean rocky infralittoral, The." Doctoral thesis, Universitat de Barcelona, 2007. http://hdl.handle.net/10803/1443.
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The discipline of ecology is habitually divided up into a whole range of different specialities, and this thesis forms part of what is commonly known as "community ecology" (Diamond and Case 1986). To be more precise, my work has centred on the degree to which the trophic relationships that exist between the organisms constituting a food web govern the structure and dynamics of the communities they form. I approached the subject from an experimental point of view and all the work was carried out in the field by means of what are referred to as "natural experiments", with all the advantages and disadvantages that this supposes. The chosen ecosystem was the coastal marine benthos or, to be more specific, rocky infralittoral communities, a propitious place in which to work since this setting has seen the production of some highly important contributions to community ecology, above all in the development of experimental techniques (review by Castilla 2000).Owing to the existence of previous investigations, my work, strictly speaking, does not break any new ground, since the subject matter has already been well studied in other oceans (see Castilla 2000 for a revision). Paradoxically, the Mediterranean, them cradle of the natural sciences (Aristotle, 350 BC) and home to the invention of scuba diving by Gagnan and Cousteau in 1944, has generally not been witness to any of the most important advances in experimental benthic science. Whilst not wanting to question the universality of discoveries regarding benthic communities made in other waters, it can surely not be an excessive precaution to attempt to understand the way regional peculiarities - the Mediterranean is a very singular sea in many ways (Margalef 1985) - affect general principals.
One highly significant way in which benthic experiments in the Mediterranean are playing a part in current debate is the role that marine reserves or protected marine areas (PMAs) can be expected to play as management tools in ecosystems adversely affected by human action. In this sense, my work shares a characteristic with many others: the use of marine reserves as experimental sites that can be compared with nearby unprotected zones in order to try and judge their worth.
As a final reflection on the main object of study in my thesis it is worth remarking that the system under study relates on a trophic level macroscopic algae - the main primary producers in the phyto-benthos - to their herbivores, which in the coastal Mediterranean benthos are essentially a sea urchin (Paracentrotus lividus), a fish, the salema (Sarpa salpa), and a guild of omnivorous fish that include optional grazers of algae and predators on sea urchins. My study investigated the interactions taking place between all the actors in this complex community and not just the interactions occurring between a certain group of species, although inevitably, given its central position, the sea urchin Paracentrotus lividus has been the focal point of our efforts. As a means of simplifying, throughout this paper I often refer to the "triangle" 'algae-sea urchins-fish', which is described in more detail in Annex 1.
I feel that my work has two main applications. Aside from any knowledge gained from the experimental study of the interactions within a complex community under natural conditions, our results have, firstly, a clear role to play in the management of coastal areas and biological conservation in general. It is known that high densities of sea urchins can cause a regression and a loss of diversity in algal communities (that can be compared to the effects of desertification on the biodiversity of forest ecosystems).
Studying experimentally the mechanisms that regulate these interactions is a way of searching for valid management criteria. Secondly, we looked at the relevance of the role played by changes of anthropic origin such as eutrophication or overfishing in the proliferation of sea urchins and the regression of algal communities.
Dins el ventall d'especialitats en que s'acostuma a dividir l'ecologia, aquesta tesi s'enquadra en l'anomenada "ecologia de comunitats" (Diamond i Case 1986). Amb més precisió, el meu treball ha estat dedicat a investigar el grau en que les relacions tròfiques entre els organismes que formen una xarxa tròfica arriben a governar l'estructura i dinàmica de la comunitat que formen. L'aproximació es experimental i tot el treball s'ha realitzat al camp, basat en el que hom anomena "experiments naturals" amb les seves virtuts i inconvenients. L'ecosistema triat ha estat el bentos marí litoral, i en concret les comunitats de l'infralitoral rocós. Es tracta d'un marc de treball favorable, ja que aquest escenari ha produït algunes de les contribucions més importants a l'ecologia de comunitats, sobretot en el que fa al desenvolupament de la seva vessant experimental (revisat per Castilla 2000).
A causa d'aquests treballs precedents, una part dels objectius del meu treball no és estrictament novedosa, ja que han estat molt estudiats en altres mars (veure Castilla 2000 per a una revisió). Paradoxalment tractant-se del mar que ha estat el bressol de les ciències naturals (Aristòtil, cap el 350 a.C.) i de la invenció de l'escafandre autònom per Gagnan i Cousteau el 1944, la Mediterrània ha quedat en gran mesura fora de l'àrea on han tingut lloc els avenços de l'ecologia bentònica experimental. Tot i que confíem en l'universalitat de les descobertes més sòlides de l'ecologia de comunitats bentòniques, mai serà una precaució excessiva per als ecòlegs copsar la forma en que les particularitats regionals (la Mediterrània es un mar en molts sentits singular; Margalef 1985) modelen aquests principis generals.
A més, almenys en una part sí que les experiències d'ecologia bentònica mediterrànies participen de la més disputada actualitat, i és en el paper que hom pot esperar que realitzin les Reserves Marines o Àrees Marines Protegides (MPA's) com eines de gestió racional d'uns ecosistemes massa castigats per l'acció humana. En aquest sentit el meu treball comparteix amb molts altres que es realitzen actualment el tret d'utilitzar les Reserves Marines com un dels tractaments experimentals estudiats i, per comparació amb el que succeeix a les zones properes no protegides, tracta d'esbrinar els seus efectes.
Per acabar de focalitzar el tema objecte de la meva tesi només cal afegir que el sistema estudiat és el que relaciona tròficament les algues macroscòpiques, com principals productors primaris del fito-bentos, amb els seus herbívors, que al bentos litoral mediterràni es poden simbolitzar en una espècie de garota de mar ("Paracentrotus lividus") i un peix ("Sarpa salpa"), i amb el gremi de peixos omnívors entre els que es compten opcionals pasturadors d'algues i depredadors de les garotes herbívores. L'estudi aborda les interaccions entre tots els elements d'una comunitat complexa, i no només d'algunes espècies selectes, encara que, pel seu paper central, la garota "Paracentrotus lividus" ha concentrat més esforços que la resta. Al llarg de la memòria i per simplificar, parlarem sovint d'aquest "triangle" algues-garotes-peixos, que es descriu amb més detalls en l'Annex 1.
Crec que l'interès d'aquest treball pot ser doble. Més enllà del coneixement que pot aportar a l'Ecologia de comunitats l'estudi experimental de les interaccions d'una comunitat complexa en condicions naturals, els resultats tenen un clar interès aplicat per a la gestió dels litorals i per a la biologia de la conservació. És sabut que altes densitats de garotes poden provocar la regressió de les comunitats algals i una forta pèrdua de diversitat (que pot ser comparada als efectes de la desertització sobre la biodiversitat dels ecosistemes forestals). Estudiant experimentalment els mecanismes que regulen aquestes interaccions busquem aportar criteris vàlids per a la gestió. Un tema d'especial interès ha estat esbrinar quin paper han pogut jugar canvis d'origen antròpic, com els derivats de l'eutrofització o de la sobre-pesca, en la proliferació de les garotes i la regressió de les comunitats algals.
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Soars, Natalie Anne. "Habitat soundscapes and sound production by tropical and temperate sea urchins and the swimming behaviour of their larvae." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/13923.
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The distribution, abundance and behaviour of soniferous organisms influence the spatial variability of underwater noise characteristics or ‘soundscape’. In this way, the soundscape provides useful information on habitat and assemblages that enables navigation in larvae and can be used for environmental assessment and monitoring. Despite the ecological importance of sea urchins and evidence they produce sound of their sound, knowledge gaps remain regarding the role of adult and larval sea urchins in acoustic ecology. In this thesis the sounds produced by 3 temperate and 3 tropical species of sea urchins were characterised. The soundscape of sea urchin habitat from important ecological systems (sea grass, temperate rocky reef, coral reef) in eastern Australia were also characterised. The sea urchins made a ‘crunching’ sound when feeding that was commonly produced around dawn, dusk or midnight. This sound ranged from 2-22 kHz with highest intensity from 2-8 kHz. Centrostephanus rodgersii appeared to contribute to a diurnal chorus between 2-8 kHz in the ‘barrens’ habitat of Jervis Bay, NSW. Analysis of the 5000 Hz 1/3rd octave band revealed a difference between barrens sites of up to 10 dB re 1 µPa2. A similar difference was found between two coral reef habitats recorded at One Tree Island, QLD. Arm angle development reflects swimming ability in sea urchin larvae and so was documented for two-armed and multi-armed larvae forms to characterise their swimming biology. In a behavioural study of early and settlement stage larvae of H. tuberculata and C. rodgersii, early stage larvae exhibited signs of negative phototaxis swimming down during the day, suggesting that they exhibit diurnal migration in the field. However, larvae did not modify this swimming behaviour in response to a reef noise. This research will enable detection of sea urchin sounds in ambient noise recordings and provides insight into the impacts of sea urchin populations on the marine soundscape.
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Poorbagher, Hadi, and n/a. "Life-history ecology of two New Zealand echinoderms with planktotrophic larvae." University of Otago. Department of Marine Science, 2008. http://adt.otago.ac.nz./public/adt-NZDU20081029.160011.
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The importance of parental nutritional status on planktotrophic larvae was investigated in both laboratory-conditioned and field (populations) parents of two New Zealand echinoderms: the sea urchin Pseudechinus huttoni and the starfish Sclerasterias mollis.
Three questions were addressed: (i) Does parental nutritional status affect the reproductive features (gonad index, gametogenesis, fecundity and biochemical composition) both in the laboratory and under natural conditions? (ii) Does parental nutritional status affect egg characteristics (diameter, number, dry weight, fertilization rate and biochemical composition)? (iii) Are the characteristics of larvae (growth, development, morphology, mortality rate and body composition) influenced by parental or larval nutrition (or both)?
To answer the first question, adult P. huttoni and S. mollis were maintained in the laboratory with a low or high diet (in terms of quantity and quality for P. huttoni, and in terms of quantity for S. mollis) for one year. The effect of low and high diets on reproductive features was studied and the same parameters were studied in two parental populations with dissimilar food availability (for P. huttoni: Otago Shelf and Doubtful Sound populations; for S. mollis: Otago inshore and offshore populations). To address the second question, egg characteristics of the laboratory-held and field parents were measured. The third question was answered by rearing larvae of the laboratory and field parents with both low and high concentration planktonic diets.
P. huttoni reared in the laboratory with a higher food ration had greater gonad indices and lipid concentration and larger oocyte area. Sea urchins from the Doubtful Sound population had higher food availability, greater gonad lipid concentration and larger oocytes.
Parental nutrition had some effect on the characteristics of the egg in P. huttoni. The laboratory-held urchins fed a high diet produced larger eggs: P. huttoni from Doubtful Sound produced larger eggs with a greater carbohydrate concentration.
P. huttoni larvae from low-fed laboratory and Otago Shelf parents had faster development The effect of larval nutrition was more important than parental food availability on larval growth and development. Feeding parents in the laboratory had no effect on larval morphology but larvae from Doubtful Sound, which had better food availability, had longer arms relative to body width. A higher cell concentration in the planktonic diet led to shorter larval arm relative to body width.
In S. mollis reared in the laboratory, a higher food ration led to larger gonad and pyloric caeca indices. The starfish from an Otago inshore population mainly had a higher gonad index than those from an Otago offshore population.
In the laboratory-held parents S. mollis, nutrition had no effect on the egg characteristics. In the field, starfish with higher food availability produced smaller eggs with lower carbohydrate concentration.
There was no significant difference between development rates of S. mollis larvae from low and high fed laboratory parents. However, those from the Otago inshore parents, with better food availability, had faster development than the larvae from Otago offshore parents.
In S. mollis larvae, the origin of the parents (either from the laboratory or the field) had no effect on larval shape. A higher concentration planktonic diet led to longer larvae relative to body width in larvae from high-fed laboratory parents.
In both P. huttoni and S. mollis, parental and larval diet had no effect on rate of instantaneous larval mortality.
In both P. huttoni and S. mollis larvae, biochemical composition of the larvae and the egg were different to each other. Egg reserves appear not to be a factor which affects larval characteristics in these species.
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Mörk, Erik. "Macroalgal community dynamics on coral reefs : Implications for management." Doctoral thesis, Stockholms universitet, Systemekologiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-48281.
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Although rather inconspicuous on healthy coral reefs, macroalgae form the basis of coral food webs. Today, macroalgae are generally increasing and many reefs undergo transitions from coral to macroalgal dominance resulting from e.g. enhanced nutrient loading or increased fishing. This thesis aims to investigate the relative importance of top-down and bottom-up regulation, and different herbivore types, on macroalgal distribution, fecundity and community composition on coral reefs. Papers I and II indicate that macroalgal abundance in a coral reef system is largely governed by top-down regulation through grazing by herbivores, while bottom-up regulation through enhanced nutrient availability rather influence algal species composition. Paper II also shows that these regulating effects are not as evident in an area with relatively strong water motion, suggesting that impacts of anthropogenic disturbance may be site-specific. Paper III shows that herbivory is an important factor influencing macroalgal growth and subsequent reproduction. Furthermore, Paper IV and V conclude that efficiency in removing macroalgal biomass is dependent on the type of dominant herbivore, where sea urchins seem to be more effective than fish. Paper IV indicates a seasonal variation in macroalgal biomass and distribution in a small geographic scale but with relatively high temporal resolution. Paper V on the other hand shows these same effects, but with a focus on geographic variation, including a large part of the East African region, as well as between year temporal variations in Kenya. Together, results from the two latter studies indicate that herbivory by fish may not be able to prevent a macroalgal bloom in a degraded system where substrate availability for algal colonization is high, but that it may still facilitate coral recovery over time. Thus, a large algal biomass may not necessarily indicate a reef beyond the possibility of recovery.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Accepted. Paper 4: Manuscript. Paper 5: Manuscript.
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Day, Elizabeth. "Ecological interactions between abalone (Haliotis midae) juveniles and sea urchins (Parechinus angulosus), off the south-west coast of South Africa." Doctoral thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/9690.
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Bibliography: 172-183.Field surveys were carried out in the kelp beds of the shallow subtidal off the south western Cape of South Africa, which confirmed the existence of a strong positive relationship between the urchins Parechinus angulosus and juveniles of the abalone Haliotis midae. Both species occupied primarily hard substrates, showing preferences for encrusting corallines. Of the juvenile abalone sampled, > 98% were found beneath sea urchins. All small (3-10 mm shell length) and medium sized (11-20 mm shell length) abalone juveniles occurred under urchins, whether on flat or vertical reef, or in crevices. A small proportion (approximately 10%) of large juveniles (21-35 mm shell length) were not found under urchins, and in these instances all occupied crevices instead. Subsequent surveys also revealed a positive, but weaker, association between abalone recruits (<3 mm shell length) and urchins - an unexpected result, given that abalone recruits are cryptic against the encrusting coralline substrate that they occupy preferentially. Thus camouflaged, they were assumed to gain little additional benefit from sheltering beneath urchins. Selectivity indices showed that, amongst different morphological categories of encrusting corallines, recruits showed preferences for strongly-textured corallines, such as the so-called "knobbly" and "paint" textures. Lower densities of recruits per unit substrate area were recorded on the smoother "velvet" corallines. However, almost all (80%) of recruits were found on velvet corallines occurred under urchins, as opposed to 28 and % of recruits on paint and knobbly corallines respectively.
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Farina, Simone. "Scale-dependent factors modulate sea urchin predation in macrophyte communities." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/325691.
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Many nearshore temperate coastal ecosystems are strongly regulated by top-down control. This is particularly true of shallow macrophyte communities, where habitat structuring is heavily dependent on the ability of predators to control populations of herbivorous sea urchins.
Released from predation pressure, urchins can quickly transform macroalgal ecosystems to unproductive barrens. While temperate seagrasses are less dramatically affected, top-down processes still play critical roles in mediating trophic interactions and habitat structure. There has been considerable attention paid to understanding the role predator numbers (mostly fish) play in influencing the strength of predator-prey interactions in macrophyte communities. However, several factors apart from abundance can influence these interactions, which have received far less attention. In this thesis, I examine how the structure of the habitat itself can mediate top trophic interactions and how these processes vary with spatial scale. I begin by exploring how predation activity varies in relation to Posidonia oceanica habitat structure. Meadows can vary considerably in their structural attributes, and in the first Chapter I examine how canopy height and the height of the unburied rhizome matte influence predation intensity. My results show that meadow structure (canopy height and unburtied matte height) within habitats play critical roles in determining predation rates in these systems by mediating the availability of benthic refuge for urchins.
I carry this work forward in Chapter two by comparing relative rates of predation across a gradient of increasing habitat structure across macrophyte communities (turf habitats, macroalgal habitats, low structured seagrass and high structured seagrass). To make these results generalizable, I compared these predation patterns across three different regional seascapes — the Caribbean, the Mediterranean and Western Australia — each with their own unique guild of fish and benthic predators. Habitat structure clearly regulated predation in all regions, but interestingly, the direction of its influence was highly dependent on the predator guild; regions dominated by visual fish predators showed a negative relationship between predation intensity and habitat structure, whereas where benthic predators (sea stars or molluscs) were common, predation increased with structure.
How nearshore habitats are distributed in space (patch configuration, the spatial relationship between patches, aggregation patterns, etc.) can have strong effects on how predators and prey species move between and within habitats and, in Chapter three I examined the influence these landscape mosaic features had on modifying trophic interactions. My results indicate that these mosaics can generate lumpiness in the distribution of trophic function, with cold- and hot-spots of predation dependent on area-perimeter relationships, the presence of rocky substrates or the degree of habitat clumping in space.
Overall, my thesis provides critical insights on how the predation function varies across scales in nearshore marine macrophyte communities. Sea urchins are often a keystone herbivore in these systems, and my thesis shows that their control is heavily influenced by the habitat itself. In particular, habitat can: (i) modify the interaction strength as a function of structure, (ii) can change the direction of the interaction depending on the dominant predator guild and (iii) generate hotspots of predation as a function of spatial configuration. My work indicates that predator abundance, while critical, does not reflect the true complexity of predator-prey interactions. Given the importance of predator-urchin dynamics to the functioning of nearshore macrophyte habitats, we need much more understanding of habitat characteristics at fine and large scales to be able to effectively manage these systems and the functions they embody.En esta tesis se examina cómo la estructura de macrófitos marinos pueden mediar las interacciones tróficas entre depredadores y herbívoros, y cómo estos procesos varían en función de la escala espacial. Se comienza explorando las variaciones de la actividad de depredación en relación a la complejidad estructural de la pradera de Posidonia oceánica. En el primer capítulo se examina cómo la cobertura foliar y el nivel de enterramiento de los rizomas influye en la intensidad de la depredación de erizos. Los resultados demuestran que la estructura de la pradera juega un papel fundamental a la hora de determinar las tasas de depredación de estos sistemas mediante el control de la disponibilidad de refugio para los erizos. En el segundo capítulo se profundiza en algunas de las cuestiones abiertas en el primer capítulo comparando las tasas de depredación en un gradiente de complejidad estructural de diferentes praderas de macrófitos. Para poder generalizar los resultados, se comparan las tendencias encontradas entre tres diferentes bioregiones —Caribe, Mediterráneo occidental y Australia occidental— cada una caracterizada por su propia composición local de depredadores. Los resultados muestran que la estructura del hábitat regula la depredación en todas las regiones estudiadas, pero que la dirección de la influencia depende de la composición local de los depredadores. En regiones dominadas por depredadores pelágicos, es decir peces, se observa una relación negativa entre la intensidad de depredación y la complejidad de la estructura de los hábitats. Por el contrario, en regiones donde dominan los depredadores bentónicos, como gasterópodos, la actividad de depredación aumenta con la complejidad de la estructura del hábitat. La forma en la que los hábitats se distribuyen en el espacio puede tener efectos muy fuertes sobre las interacciones depredador-presa. En el tercer capítulo se examina la influencia de las características del paisaje de una pradera de P. oceánica fragmentada sobre la depredación. Los resultados indican que un paisaje en mosaico puede generar una distribución heterogénea del proceso de depredación determinando “puntos-fríos” y “puntos-calientes” de depredación en función de la complejidad estructural de las manchas, de la presencia de roca como refugio y del grado de agregación de estas características en el espacio. En definitiva esta tesis ofrece un estudio exhaustivo sobre como varía el proceso de depredación en las comunidades de macrófitos a diferentes escalas espaciales. La presente tesis demuestra que la estructura del hábitat es un factor regulador de la depredación de erizos, un componente clave en la cadena trófica de estos ecosistemas.
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Schäfer, Sabine [Verfasser]. "Reproductive disorders in sea urchins (Psammechinus miliaris) caused by environmental pollutants / Sabine Schäfer. Alfred Wegener Institute for Polar and Marine Research." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2010. http://d-nb.info/1034994751/34.
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Rendina, Francesco. "Effects of acute temperature increase on performance and survival of Caribbean echinoids." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10050/.
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Climate change is occurring at a faster rate than in the past, with an expected increase of mean sea surface temperatures up to 4.8°C by the end of this century. The actual capabilities of marine invertebrates to adapt to these rapid changes has still to be understood. Adult echinoids play a crucial role in the tropical ecosystems where they live. Despite their role, few studies about the effect of temperature increase on their viability have been reported in literature. This thesis work reports a first systematic study on several Caribbean echinoids about their tolerance to temperature rise in the context of global warming. The research - carried out at the Bocas del Toro Station of the Smithsonian Tropical Research Institute, in Panama - focalized on the 6 sea urchins Lytechinus variegatus, L. williamsi, Echinometra lucunter, E. viridis, Tripneustes ventricosus and Eucidaris tribuloides, and the 2 sand dollars Clypeaster rosaceus and C. subdepressus. Mortality and neuromuscular well-being indicators - such as righting response, covering behaviour, adhesion to the substrate, spine and tube feet movements - have been analysed in the temperature range 28-38°C. The righting time RT (i.e., the time necessary for the animal to right itself completely after inversion) measured in the 6 sea urchin species, demonstrated a clearly dependence on the water temperature. The experiments allowed to determine the “thermal safety margin” (TSM) of each species. Echinometra lucunter and E. viridis resulted the most tolerant species to high temperatures with a TSM of 5.5°C, while T. ventricosus was the most vulnerable with a TSM of only 3°C. The study assessed that all the species already live at temperatures close to their upper thermal limit. Their TSMs are comparable to the predicted temperature increase by 2100. In absence of acclimatization to such temperature change, these species could experience severe die-offs, with important consequences for tropical marine ecosystems.
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Stumpp, Meike [Verfasser]. "Mechanismen der CO2-Toleranz bei Seeigeln des Genus Strongylocentrotus = Mechanisms of CO2 tolerance in sea urchins of the genus Strongylocentrotus / Meike Stumpp." Kiel : Universitätsbibliothek Kiel, 2011. http://d-nb.info/1020200804/34.
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Cavalcanti, Augusto Muniz. "Dieta do ouri?o-branco, Tripneustes ventricosus (Lamarck, 1816), no Arquip?lago de Fernando de Noronha, PE." Universidade Federal do Rio Grande do Norte, 2007. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12473.
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Sea urchins are benthic macroinvertebrates that inhabit shallow coastal waters in tropical and temperate zones. Urchins are usually classified as generalists or omnivores as they can adjust their diet according to the food resources available in the environment. Due to the strong grazing pressure they may exert, urchins have an important role in marine ecosystems, occupying different trophic levels and stimulating the intensification of the dynamics of communities where they occur. In 2004, a monitoring program focused on the population dynamics of the white sea urchin, Tripneustes ventricosus, has been initiated in the Fernando de Noronha Archipelago. At the same time, a surprisingly lack of information on the species biology has been noted, despite their wide geographical distribution and economic importance in many parts of its range. Hence, this work was developed to provide information on the feeding habits of T. ventricosus in the archipelago. Ten specimens were collected between December 2006 and July 2007 at two sites of the archipelago, Air France and Sueste Bay for biometrics and analysis of gut contents. Test diameters ranged from 9.19 cm (? 1.1) to 10.08 cm (? 0.58). Calculated stomach repletion index (IRE) was higher (p <0.05) in the Air France site and also during January and July. The IRE was not correlated to the gonad index. Fifteen different species of algae were detected in a total of 120 stomachs examined: 4 Chlorophytas, 4 Phaeophytas and 6 Rhodophytas. Food diversity (p <0.05) was higher in December 2006 and January 2007. Although several items had a high frequency of occurrence, they were low represented in terms of weight, and consequently, had a low level of relative importance. The brown algae Dictyopteris spp and Dictyota spp, followed by the green algae Caulerpa verticillata accounted for the greatest importance in T. ventricosus diet, comprising about 90% of the consumed items
Os ouri?os-do-mar s?o macroinvertebrados bent?nicos que habitam ?guas rasas costeiras em zonas tropicais e temperadas. Os ouri?os s?o geralmente classificados como generalistas ou on?voros por adaptarem sua dieta de acordo com a disponibilidade dos recursos alimentares dispon?veis no ambiente. Devido ? forte press?o de pastagem que exercem, os ouri?os possuem importante papel em ecossistemas marinhos ocupando diversos n?veis tr?ficos e estimulando a intensifica??o da din?mica das comunidades onde ocorrem. Em 2004 foi dado in?cio a um programa de monitoramento das popula??es do ouri?o-branco, Tripneustes ventricosus, quando se percebeu a car?ncia de informa??es sobre a esp?cie, apesar de sua ampla distribui??o e import?ncia econ?mica. Dessa forma, o presente trabalho visou obter informa??es referentes aos h?bitos alimentares de T. ventricosus no arquip?lago de Fernando de Noronha. Durante os meses de dezembro de 2006, janeiro, fevereiro, abril, maio e julho de 2007 foram amostrados 10 indiv?duos de T. ventricosus nas regi?es do Air France e na ba?a do Sueste. Foram realizadas biometrias e an?lises dos itens presentes no conte?do estomacal dos organismos. O di?metro m?dio de carapa?a dos ouri?os amostrados variou entre 9,19 cm (? 1,1) e 10,08 cm (? 0,58). Os ?ndices de reple??o dos conte?dos estomacais (IRE) foram mais elevados (p<0,05) na regi?o do Air France e durante os meses de janeiro e julho de 2007. Foi verificado que o IRE variou independentemente do ?ndice gonadal. Quinze diferentes esp?cies de algas foram encontradas nos 120 conte?dos estomacais analisados: 4 Chlorophytas, 4 Phaeophytas e 6 Rhodophytas, sendo que a maior (p<0,05) diversidade alimentar foi observada nos meses de dezembro de 2006 e janeiro de 2007. Apesar da freq??ncia de ocorr?ncia de alguns dos itens ser alta, suas representatividades em peso foram bastante baixas o que lhes confere um baixo ?ndice de import?ncia relativa. As algas pardas dos g?neros Dictyopteris e Dictyota, seguidas da alga verde Caulerpa verticillata representaram a maior import?ncia na dieta de T. ventricosus nas ?reas amostradas, compondo aproximadamente 90% da dieta da esp?cie no local
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Dos, Ramos Catarino Ana Isabel. "Temperate and cold water sea urchin species in an acidifying world: coping with change?" Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209914.
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Anthropogenic carbon dioxide (CO2) emissions are increasing the atmospheric CO2 concentration and the oceans are absorbing around 1/3 them. The CO2 hydrolysis increases the H+ concentration, decreasing the pH, while the proportions of the HCO3- and CO32- ions are also affected. This process already led to a decrease of 0.1 pH units in surface seawater. According to "business-as-usual" models, provided by the Intergovernmental Panel on Climate Change (IPCC), the pH is expected to decrease 0.3-0.5 units by 2100 and 0.7-0.8 by 2300. As a result the surface ocean carbonates chemistry will also change: with increasing pCO2, dissolved inorganic carbon will increase and the equilibrium of the carbonate system will shift to higher CO2 and HCO3– levels, while CO32– concentration will decrease. Surface seawaters will progressively become less saturated towards calcite and aragonite saturation state and some particular polar and cold water regions could even become completely undersaturated within the next 50 years. Responses of marine organisms to environmental hypercapnia, i.e. to an excess of CO2 in the aquatic environment, can be extremely variable and the degree of sensitivity varies between species and life stages. Sea urchins are key stone species in many marine ecosystems. They are considered to be particularly vulnerable to ocean acidification effects not only due to the nature of their skeleton (magnesium calcite) whose solubility is similar or higher than that of aragonite, but also because they lack an efficient ion regulatory machinery, being therefore considered poor acid-base regulators. Populations from polar regions are expected to be at an even higher risk since the carbonate chemical changes in surface ocean waters are happening there at a faster rate.
The goal of this work was to study the effects of low seawater pH exposure of different life stages of sea urchins, in order to better understand how species from different environments and/or geographic origins would respond and if there would be scope for possible adaptation and/or acclimatization.
In a first stage we investigated the effects of ocean acidification on the early stages of an intertidal species from temperate regions, the Atlantic Paracentrotus lividus sea urchin, and of a sub-Antarctic species, Arbacia dufresnei. The fertilization, larval development and larval growth were studied on specimens submitted through different pH experimental treatments. The fertilization rate of P. lividus gametes whose progenitors came from a tide pool with high pH decrease was significantly higher, indicating a possible acclimatization or adaptation of gametes to pH stress. Larval size in both species decreased significantly in low pH treatments. However, smaller A. dufresnei echinoplutei were isometric to those of control treatments, showing that size reduction was most likely due to a slower growth rate. In the pH 7.4 (predicted for 2300) treatment, P. lividus presented significantly more abnormal forms than control ones, but A. dufresnei did not. The latter does not seem to be more vulnerable than temperate species, most likely due to acclimatization/adaptation to lower pH seasonal fluctuations experienced by individuals of this population during spring time.
In a second stage, adult physiological responses of P. lividus and A. dufresnei to low pH seawaters were studied. Intertidal field P. lividus specimens can experience pH fluctuations of 0.4 units during low tidal cycles, but their coelomic fluid pH will not change. During experimental exposure to low pH, the coelomic fluid (extracellular) pH of both species decreased after weeks of exposure to low seawater pH. However, it owned a certain buffer capacity (higher than that of seawater) which did not seem to be related to passive skeleton dissolution. In laboratory studies, the feeding rate of P. lividus, the RNA/DNA ratio (proxy for protein synthesis and thus metabolism) of both the gonads and the body wall of the studied species and the carbonic anhydrase activity in the body wall (an enzyme involved in calcification and respiratory processes) of A. dufresnei did not differ according to seawater pH. The same was true for spine regeneration (a proxy for calcification) of both species. This shows that both P. lividus and A. dufresnei are able to cope when exposed to mild hypercapnia (lowest investigated pH 7.4) for a mid-term period of time (weeks). In a different set of experiments, pH effects were tested on P. lividus individuals together with two temperatures (10ºC and 16ºC). The pH decrease of the coelomic fluid did not vary between temperatures, neither did its buffer response. The oxygen uptake rates of P. lividus (as a proxy for global metabolic state of the whole organism) increased in lower pH treatments (7.7 and 7.4) in organisms exposed to lower temperatures (10ºC), showing that this was upregulated and that organisms experienced a higher energetic demand to maintain normal physiological functions. For instance, gonad production (given by the RNA/DNA ratio) was not affected neither by temperature, nor pH.
Finally, possible morphological and chemical adaptations of cidaroid (“naked”) spines, which are not covered by epidermis, to low magnesium calcite saturation states were investigated. Deep sea field specimens from the Weddell Sea (Antarctica), Ctenocidaris speciosa were studied. Cidaroid spines have an exterior skeleton layer with a polycrystalline constitution that apparently protects the interior part of the monocrystaline skeleton, the stereom (tridimensional magnesium calcite lattice). The cortex of C. speciosa was by its turn divided into two layers. From these, it presented a thicker inner cortex layer and a lower Mg content in specimens collected below the aragonite saturation horizon. The naked cortex seems able to resist to low calcium carbonate saturation state. We suggest that this could be linked to the important organic matrix that surrounds the crystallites of the cortex.
Some echinoid species present adaptive features that enable them to deal with low pH stresses. This seems to be related to the environmental conditions to which populations are submitted to. Therefore, organisms already submitted to pH daily or seasonal fluctuations or living in environments undersaturated in calcium carbonate seem to be able to cope with environmental conditions expected in an acidified ocean. Under the realistic scenario of a decrease of ca. 0.4 units of pH by 2100, sea urchins, and echinoderms in general, appear to be robust for most studied processes. Even thought, this general response can depend on different parameters such as exposure time, pH level tested, the process and the life stage considered, our results show that there is scope for echinoids to cope with ocean acidification.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished