Journal articles on the topic 'Algal feeding'
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1
McAuley, P. J. "The cell cycle of symbiotic Chlorella. I. The relationship between host feeding and algal cell growth and division." Journal of Cell Science 77, no. 1 (August 1, 1985): 225–39. http://dx.doi.org/10.1242/jcs.77.1.225.
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When green hydra were starved, cell division of the symbiotic algae within their digestive cells was inhibited, but algal cell growth, measured as increase in either mean volume or protein content per cell, was not. Therefore, control of algal division by the host digestive cells must be effected by direct inhibition of algal mitosis rather than by controlling algal cell growth. The number of algae per digestive cell increased slightly during starvation, eventually reaching a new stable level. A number of experiments demonstrated that although there was a relationship between host cell and algal mitosis, this was not causal: the apparent entrainment of algal mitosis to that of the host cells could be disrupted. Thus, there was a delay in algal but not host cell mitosis when hydra were fed after prolonged starvation, and algae repopulated starved hydra with lower than normal numbers of algae (reinfected aposymbionts or hydra transferred to light after growth in continuous darkness). Two experiments demonstrated a direct stimulation of algal cell division by host feeding. Relationships of algal and host cell mitosis to numbers of Artemia digested per hydra were different, and in hydra fed extracted Artemia algal, but not host cell, mitosis was reduced in comparison to that in control hydra fed live shrimp. It is proposed that algal division may be dependent on a division factor, derived from host digestion of prey, whose supply is controlled by the host cells. Numbers of algae per cell would be regulated by competition for division factor, except at host cell mitosis, when the algae may have temporarily uncontrolled access to host pools of division factor. The identity of the division factor is not known, but presumably is a metabolite needed by both host cells and algae.
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Figueiredo, Joana, Luís Narciso, Ralph Turingan, and Junda Lin. "Efficiency of using emerald crabs Mithraculus sculptus to control bubble alga Ventricaria ventricosa (syn. Valonia ventricosa) in aquaria habitats." Journal of the Marine Biological Association of the United Kingdom 88, no. 1 (February 2007): 95–101. http://dx.doi.org/10.1017/s0025315408000192.
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Ornamental crabs of the genus Mithraculus (Decapoda: Brachyura: Majidae) are utilized in reef aquaria to control nuisance algae, particularly bubble algae. Although Mithraculus have modified, spooned-shaped chelae to feed on both fleshy and filamentous algae, they may consume alternative foods offered in a reef aquarium. The objective of this study was to determine the efficiency of using Mithraculus sculptus to control the bubble alga Ventricaria ventricosa (Siphonocladales–Cladophorales complex, Chlorophyta) in the presence of alternative foods (commercial pellets and frozen mysids) commonly utilized in reef aquaria. Results indicated that medium and large sized crabs consumed more bubble algae than smaller conspecifics. Although, M. sculptus first chose alternative foods to bubble alga (77% and 69% of the time chose pellets and frozen mysids, respectively), algal consumption only decreased significantly if, besides algae, pellets were provided; when only algae were provided, algal consumption was similar to when they were provided with mysids. The prey choice model was used as a conceptual framework to study the mechanisms underlying active selection; food energy content and handling time were measured and food profitability was calculated. Handling time decreased with increasing crab size. Pellets presented a higher profitability than algae but mysids and algae presented similar profitability; this seems to be in agreement with the observed reduced algal consumption when pellets made part of the diet. Mithraculus sculptus feeding behaviour on V. ventricosa recorded with digital high-speed video (DHSV) suggests that as the crab tears the algal cell apart, the cell liquid that contains juvenile cytoplasmatic spheres is released into the water; this behaviour might contribute to algal dispersal and consequently algal infestation. These results seem to indicate that M. sculptus might not be such an efficient bio-controller of the pest V. ventricosa as previously thought, particularly when pellets are used as food; however, its bio-control efficiency might be improved if, mysids are used as food.
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Smith, Daniel Wilkins. "Biological Control of Excessive Phytoplankton Growth and the Enhancement of Aquacultural Production." Canadian Journal of Fisheries and Aquatic Sciences 42, no. 12 (December 1, 1985): 1940–45. http://dx.doi.org/10.1139/f85-240.
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A method is proposed to control phytoplankton biomass in aquacultural ponds, using both zooplankton and filter-feeding silver carp (Hypophthalmichthys molitrix). The technique maintains co-existence of zooplankton and filter-feeding fish by excluding the fish from part of the water column. Zooplankton, which feed on smaller algal species, and silver carp, which feed on large algae and zooplankton, together can consume all sizes of phytoplankton, thus controlling algal biomass. This technique was tested in 1000-L tanks, some containing channel catfish (Ictalurus punctatus) alone, some both catfish and silver carp, and others catfish and silver carp with a zooplankton refuge. The refuge permitted coexistence of high densities of large zooplankters with the filter-feeding fish. This combination of filter-feeders reduced algal biomass by as much as 99%, increased phytoplankton diversity, and showed a trend toward improved silver carp growth compared with treatments without a refuge. The proposed technique could be applied to both intensive and extensive aquacultural systems.
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DUNN, KENNETH. "Growth of endosymbiotic algae in the green hydra, Hydra viridissima." Journal of Cell Science 88, no. 5 (December 1, 1987): 571–78. http://dx.doi.org/10.1242/jcs.88.5.571.
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Stable endosymbiosis depends upon balanced growth of the symbionts. In green hydra, coincident patterns of host and algal mitotic index suggest that coordinated reproduction provides for balanced growth. However, when hydra shrink during food shortage, the population of endosymbiotic algae in a green hydra must likewise decline in size. Thus far, no mechanism of reducing the size of the endosymbiont population has been described. Algal mitosis was found here to be stimulated by host feeding and clumped in its distribution among host cells, supporting the notion of some degree of control of algal mitosis exercised at the level of the host cell. However, comparisons of the rates of algal mitosis with the realized rates of algal population growth show that substantial numbers of algae disappear from hydra, in numbers in excess even of those necessary to accommodate host shrinkage. Only a small proportion of these lost algae was found to be expelled by hydra. Microscopic observations of the cells of macerated hydra show evidence of algal disintegration in nearly 50 % of the digestive epithelial cells of regularly fed hydra. Coincidence of remnants of algal cells and food-derived materials within the same vacuoles suggests that algae are digested by host cells.
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Iken, K., E. R. Barrera-Oro, M. L. Quartino, R. J. Casaux, and T. Brey. "Grazing by the Antarctic fish Notothenia coriiceps: evidence for selective feeding on macroalgae." Antarctic Science 9, no. 4 (December 1997): 386–91. http://dx.doi.org/10.1017/s0954102097000497.
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In Potter Cove, King George Island, Antarctica, macroalgae provide a significant food resource for herbivores. The demersal fish Notothenia coriiceps feeds on macroalgae. Eighteen algal species were identified in stomach contents: two chlorophytes, ten rhodophytes and six phaeophytes. Among these the rhodophyte Palmaria decipiens, the phaeophyte Desmarestia menziesii and the chlorophyte Monostroma hariotii comprised the greatest proportions of algal biomass. A food selection study showed four algae to be preferred (P. decipiens, M. hariotii, D. menziesii, Iridaea cordata) and two species to be avoided (Desmarestia anceps and Himantothallus grandifolius) by N. coriiceps. The present investigation indicates that this fish feeds not only intentionally, but also selectively, on macroalgae. Preference for particular algal species is not related to associated epifaunal biomass or to associated amphipod biomass.
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Ngugi, David Kamanda, Sou Miyake, Matt Cahill, Manikandan Vinu, Timothy J. Hackmann, Jochen Blom, Matthew D. Tietbohl, Michael L. Berumen, and Ulrich Stingl. "Genomic diversification of giant enteric symbionts reflects host dietary lifestyles." Proceedings of the National Academy of Sciences 114, no. 36 (August 23, 2017): E7592—E7601. http://dx.doi.org/10.1073/pnas.1703070114.
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Herbivorous surgeonfishes are an ecologically successful group of reef fish that rely on marine algae as their principal food source. Here, we elucidated the significance of giant enteric symbionts colonizing these fishes regarding their roles in the digestive processes of hosts feeding predominantly on polysiphonous red algae and brown Turbinaria algae, which contain different polysaccharide constituents. Using metagenomics, single-cell genomics, and metatranscriptomic analyses, we provide evidence of metabolic diversification of enteric microbiota involved in the degradation of algal biomass in these fishes. The enteric microbiota is also phylogenetically and functionally simple relative to the complex lignocellulose-degrading microbiota of terrestrial herbivores. Over 90% of the enzymes for deconstructing algal polysaccharides emanate from members of a single bacterial lineage, “Candidatus Epulopiscium” and related giant bacteria. These symbionts lack cellulases but encode a distinctive and lineage-specific array of mostly intracellular carbohydrases concurrent with the unique and tractable dietary resources of their hosts. Importantly, enzymes initiating the breakdown of the abundant and complex algal polysaccharides also originate from these symbionts. These are also highly transcribed and peak according to the diel lifestyle of their host, further supporting their importance and host–symbiont cospeciation. Because of their distinctive genomic blueprint, we propose the classification of these giant bacteria into three candidate genera. Collectively, our findings show that the acquisition of metabolically distinct “Epulopiscium” symbionts in hosts feeding on compositionally varied algal diets is a key niche-partitioning driver in the nutritional ecology of herbivorous surgeonfishes.
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McAuley, P. J. "The cell cycle of symbiotic Chlorella241. II. The effect of continuous darkness." Journal of Cell Science 77, no. 1 (August 1, 1985): 241–53. http://dx.doi.org/10.1242/jcs.77.1.241.
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When green hydra were grown in continuous darkness the mean cell size of their symbiotic algae was smaller than when grown in light and numbers of algae per digestive cell were reduced. The former was due to a reduction in size at which the algae divided, and the latter to a loss of synchrony of algal mitosis with that of digestive cells after transfer to darkness. Eventually, algal mitosis regained synchrony with that of digestive cells. Division synchrony was not lost in reinfected hydra (with lower than normal numbers of algae per cell) transferred to darkness; this, and the observation that synchrony in normal animals transferred to darkness was regained when algal numbers per cell had fallen to a new, lower level, suggested that the initial inhibition of algal mitosis was due to competition for a limited supply of heterotrophically required metabolites. When dark-grown hydra were returned to light there was no delay in algal division and a steady increase in the size of dividing cells, suggesting that the smaller division size in darkness was not due simply to the critical size for division being set at a lower value. In light, algal division size varied with frequency of host feeding, but this had less effect on algal division size in darkness. It is suggested that the critical cell size that algae must attain before being able to complete the cell cycle is the same in light and darkness, but in light mitosis is restricted by some exogenous factor so that algae grow beyond the critical size without dividing. In darkness both algal cell growth and division are dependent on exogenously supplied metabolites, and cell growth rather than the division factor is limiting. The precise nature of the restriction on algal division remains unknown.
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Roach, Ty N. F., Mark Little, Milou G. I. Arts, Joel Huckeba, Andreas F. Haas, Emma E. George, Robert A. Quinn, et al. "A multiomic analysis of in situ coral–turf algal interactions." Proceedings of the National Academy of Sciences 117, no. 24 (June 1, 2020): 13588–95. http://dx.doi.org/10.1073/pnas.1915455117.
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Viruses, microbes, and host macroorganisms form ecological units called holobionts. Here, a combination of metagenomic sequencing, metabolomic profiling, and epifluorescence microscopy was used to investigate how the different components of the holobiont including bacteria, viruses, and their associated metabolites mediate ecological interactions between corals and turf algae. The data demonstrate that there was a microbial assemblage unique to the coral-turf algae interface displaying higher microbial abundances and larger microbial cells. This was consistent with previous studies showing that turf algae exudates feed interface and coral-associated microbial communities, often at the detriment of the coral. Further supporting this hypothesis, when the metabolites were assigned a nominal oxidation state of carbon (NOSC), we found that the turf algal metabolites were significantly more reduced (i.e., have higher potential energy) compared to the corals and interfaces. The algae feeding hypothesis was further supported when the ecological outcomes of interactions (e.g., whether coral was winning or losing) were considered. For example, coral holobionts losing the competition with turf algae had higher Bacteroidetes-to-Firmicutes ratios and an elevated abundance of genes involved in bacterial growth and division. These changes were similar to trends observed in the obese human gut microbiome, where overfeeding of the microbiome creates a dysbiosis detrimental to the long-term health of the metazoan host. Together these results show that there are specific biogeochemical changes at coral–turf algal interfaces that predict the competitive outcomes between holobionts and are consistent with algal exudates feeding coral-associated microbes.
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Wenderoth, Heinz. "Phycoerythrin: Release from Cryptophycean Algae and Bilin Storage by the Primitive Metazoon Trichoplax adhaerens (Placozoa)." Zeitschrift für Naturforschung C 49, no. 7-8 (August 1, 1994): 458–63. http://dx.doi.org/10.1515/znc-1994-7-811.
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Animal species that store bilins from external sources are very rare. A new example is described here. - Since the primitive marine metazoon Trichoplax adhaerens stains crimsonred when feeding on a phycoerythrin-containing alga. i.e. Pyrenomonas sp. (Cryptophyceae), the question arose whether an algal pigment can be identified as the staining matter. Thin layer chromatography and visible light absorption spectrography of aqueous Trichoplax extract disclosed several bilin components representing chromophores of phycoerythrin, a photosynthetic antenna protein that occurs only in certain algae and cyanobacteria. - Additional experiments showed that a cell-free Trichoplax extract kills and incompletely digests Pyrenomonas algae releasing phycoerythrin into the medium. These digestive faculties of Trichoplax tissue components, probably enzymes, contribute to the animal’s natural feeding mechanisms that proceed extra-as well as intracorporally. While the large apoprotein component of phycoerythrin is metabolized as a nutrient, the remaining chromophore bilins, strikingly coloured tetrapyrroles, are stored within Trichoplax’ distinct cellular inclusions, staining the animal crimson
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Hong, Jiarong, Siddharth Talapatra, Joseph Katz, Patricia A. Tester, Rebecca J. Waggett, and Allen R. Place. "Algal Toxins Alter Copepod Feeding Behavior." PLoS ONE 7, no. 5 (May 18, 2012): e36845. http://dx.doi.org/10.1371/journal.pone.0036845.
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Dvir, Irit, Reuven Chayoth, Uriel Sod-Moriah, Shraga Shany, Abraham Nyska, Aliza H. Stark, Zecharia Madar, and Shoshana Malis Arad. "Soluble polysaccharide and biomass of red microalgaPorphyridiumsp. alter intestinal morphology and reduce serum cholesterol in rats." British Journal of Nutrition 84, no. 4 (October 2000): 469–76. http://dx.doi.org/10.1017/s000711450000177x.
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The present study investigated the effects of the red microalgaPorphyridiumsp. on gastrointestinal physiology and lipid metabolism in male Sprague-Dawley rats. Diets containing dietary fibre from pelleted red microalgal cells (biomass) or their sulfated polysaccharide, pectin or cellulose (control) were fed to rats for a period of 30 d. All three fibre-supplemented diets increased the length of both the small intestine and colon, with a significantly greater effect in rats fed the algal polysaccharide. The polysaccharide also increased mucosa and muscularis cross-sectional area of the jejunum, and caused hypertrophy in the muscularis layer. The algal biomass significantly lowered gastrointestinal transit time by 44 % in comparison with the control rats. Serum and mucosal cholecystokinin levels were lower in rats on the pectin and polysaccharide diets, while cholecystokinin levels in rats fed algal biomass were not different from those in the control animals. In comparison with the control diet, all the experimental diets significantly lowered serum cholesterol levels (22–29 %). Feeding of non-fermentable algal polysaccharide or biomass significantly increased faecal weight and bile acid excretion compared with pectin-fed or control rats. The algal polysaccharide and biomass were thus shown to be potent hypocholesterolaemic agents active at low concentrations in the diet. Both metabolic and morphological changes were observed following consumption of algae, suggesting several possible mechanisms by which the alga affects lipid metabolism. The results presented in the present study encourage the use of red microalga as a functional food.
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Trowbridge, Cynthia D., Yayoi M. Hirano, and Yoshiaki J. Hirano. "Interaction webs of marine specialist herbivores on Japanese shores." Journal of the Marine Biological Association of the United Kingdom 89, no. 2 (March 2009): 277–86. http://dx.doi.org/10.1017/s002531540900318x.
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Marine specialist herbivores inhabiting Japanese rocky shores are significantly more diverse than in other biogeographical regions at comparable latitudes. The interaction webs of specialist sacoglossans were investigated on the Pacific shore of Honshu, Japan. The host use of the small stenophagous sacoglossan opisthobranch Placida sp. (sensu Baba, 1986) was investigated in association with the green macroalgae Codium spp. Based on field associations, Placida sp. attacked six congeneric algal host species out of eight investigated (75%) in and around Sagami Bay and ten of 20 species (50%) in Japan. In pairwise-choice feeding experiments, Placida sp. preferred the algal host from which it was collected (source alga) to alternate host and non-host algae. Preference rankings, however, could be altered based on the condition or identity of the choices (e.g. old versus young fronds of C. fragile). Connectance values were lower in these high-diversity assemblages than in their low-diversity counterparts on other temperate shores (but these values may increase with additional study). The sacoglossan occasionally coexisted with two other common sacoglossan species (Elysia trisinuata and E. setoensis) and several other less common ones. However, interspecific feeding interactions appeared minor, with no discernible evidence of interference or exploitation competition. Despite the diverse assemblage of specialist sacoglossans feeding on Codium spp., these Japanese sacoglossans (1) had low niche differentiation, (2) were weak interactors with their hosts, and (3) had negligible intra-guild interactions.
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Pleissner, Daniel, Kim Lundgreen, Florian Lüskow, and Hans Ulrik Riisgård. "Fluorometer Controlled Apparatus Designed for Long-Duration Algal-Feeding Experiments and Environmental Effect Studies with Mussels." Journal of Marine Biology 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/401961.
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Experimental feeding and growth studies on filter-feeding organisms often rely on constant algal concentrations maintained over extended periods of time. Here we present a fluorometer controlled apparatus (FCA) designed for feeding experiments with suspension-feeding mussels at naturally low chlorophyllaconcentrations above 0.5 µg L−1. The principle used is feedback regulation of the algal concentration based on continuous monitoring of the fluorescence intensity of chlorophyllain water pumped through the apparatus from an aquarium with mussels. The filtration rate is monitored continuously as the rate of change of measured volume of an algal stock added to the aquarium for keeping a constant algal concentration. As an example, the FCA has been used to study the filtration rates of blue mussels (Mytilus edulis) at algal concentrations both near and above the incipient saturation level for reduced filtration activity. As another example to put the FCA into perspective as a reliable method for environmental effect studies, the apparatus has been used to demonstrate the acute effect of changing salinity on the filtration rate ofM. edulis.
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Green-Johnson, Julia M., Kathy Johnson, Adriana Masotti, Lisa Wagar, Sherry Fillmore, Kathleen Glover, Leslie MacLaren, Cathy Enright, and Alan Fredeen. "Effects of dietary algal supplementation on bovine immunity (39.50)." Journal of Immunology 182, no. 1_Supplement (April 1, 2009): 39.50. http://dx.doi.org/10.4049/jimmunol.182.supp.39.50.
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Abstract Marine algae are primary producers of long chain omega-3 fatty acids and can serve as novel dairy feed supplements with the added potential to influence bovine immunity. Our objective was to assess the immunomodulatory impact of dietary supplementation with different algal types (macroalgae and microalgae). Effects of dietary algal supplementation were examined using a crossover design and a 28 day feeding period with each algal type. Primary immunization with Keyhole Limpet Hemocyanin (KLH) was carried out 8 days into the trial, with secondary immunization 14 days later. KLH-specific serum IgG responses were significantly higher in cows receiving macroalgae-supplemented feed than in cows receiving microalgae-supplemented feed. In contrast, cows receiving microalgae-supplemented feed showed significantly higher levels of macrophage oxidative burst activity in response to PMA challenge in vitro. These results suggest that dietary supplementation with algal products has immunomodulatory potential and also indicates that the effects on cellular and humoral immunity are dependent on the type of algae used. Funded by the Atlantic Innovation Fund.
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PEREIRA, R. C., M. D. PINHEIRO, V. L. TEIXEIRA, and B. A. P. da GAMA. "Feeding preferences of the endemic gastropod Astraea latispina in relation to chemical defenses of Brazilian tropical seaweeds." Brazilian Journal of Biology 62, no. 1 (February 2002): 33–40. http://dx.doi.org/10.1590/s1519-69842002000100005.
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Seaweed preference by the Brazilian endemic gastropod Astraea latispina was examined in the laboratory to evaluate the role of secondary metabolites in determining food choice. Of three species of seaweeds examined, Plocamium brasiliense was highly preferred; less so were Sargassum furcatum and Dictyota cervicornis were preferred less. Extracts and/or pure major metabolites of the two potentially chemically-defended seaweeds (P. brasiliense and D. cervicornis) were tested as feeding deterrents against A. latispina. Algal extract assays demonstrated that three concentrations of crude organic extract of the red alga P. brasiliense (50%, 100%: natural concentration, and 200% of dry weight: dw) did not affect feeding of this gastropod. In contrast, the three concentrations of crude organic extract of the brown alga D. cervicornis (50%, 100% and 200% dw) inhibited feeding by A. latispina. The chemical deterrent property of D. cervicornis extract against the gastropod A. latispina occurred due to a mixture of the secodolastane diterpenes isolinearol/linearol (4:1 -- 0.08% dry weight). This is the first report showing that Dictyota cervicornis produces a chemical defense against herbivores using secodolastane diterpenoid. In addition, these results widen the action spectrum of secondary metabolites found in seaweed belonging to this brown algal genus.
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Tuya, F., J. A. Martín, G. M. Reuss, and A. Luque. "Food preferences of the sea urchin Diadema antillarum in Gran Canaria (Canary Islands, central-east Atlantic Ocean)." Journal of the Marine Biological Association of the United Kingdom 81, no. 5 (October 2001): 845–49. http://dx.doi.org/10.1017/s0025315401004672.
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Preferences of the sea urchin Diadema antillarum (Echinodermata: Echinoidea) feeding on five species of brown macroalgae (Padina pavonica, Dyctiota dychotoma, Cystoseira abies-marina, Lobophora variegata and Halopteris filicina) have been studied using caging field experiments on Gran Canaria Island during August to October 2000. Results of three assays of both single and multiple diet experiments rejected the null hypothesis that Diadema does not feed selectively on the five selected algal species. In the multiple diet assays, Diadema consumed an average of 68–98 mg algae urchin−1 h−1 and 4–120 mg algae urchin−1 h−1 in the single diet experiments. On the basis of consumption, the five species of algae eaten can be divided into three groups. Thus Halopteris, Lobophora and Dyctiota were considered preferred algae, while Padina was considered an intermediate alga. Finally Cystoseira was significantly the less preferred and consumed seaweed in all sets of assays.
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Jiang, H., and GA Paffenhöfer. "Vortical feeding currents in nauplii of the calanoid copepod Eucalanus pileatus." Marine Ecology Progress Series 638 (March 19, 2020): 51–63. http://dx.doi.org/10.3354/meps13250.
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The goal of this study was to quantify feeding-current generation processes in mid to late nauplii and early copepodites of the calanoid copepod Eucalanus pileatus. Using a high-speed microscale imaging system (HSMIS) to conduct both microvideography and micro-particle image velocimetry (µPIV), free-swimming nauplii of E. pileatus were shown to use a novel ‘double draw-and-cut’ continuous appendage beat pattern, which is nonreciprocal, to generate a vortical feeding current at a Reynolds number of ~0.8. The feeding current consists of a core flow towards the ventral surface and 2 laterally flanking viscous vortices reinforcing the core flow. This feeding current is spatially limited with an r-3 decay, potentially reducing predation by rheotactic predators. The feeding current displaces water at ~1.0 × 106 naupliar body volumes per day towards the mouthpart zone. This would result in a clearance rate providing sufficient food at a relatively high environmental food concentration. HSMIS videos revealed that E. pileatus nauplii combine their feeding current and swimming motion to displace algae towards their mouth for capture, and can react to an incoming alga at a 300-500 µm distance away from the nearest naupliar setae, indicating remote detection presumably via chemoreception. The r-3-decay naupliar feeding current is suggested to enhance chemoreception by more effectively elongating the algal phycosphere towards the nauplius. Compared with nauplii, E. pileatus early copepodites, being larger in size and negatively buoyant, beat appendages in a more complex, intermittent pattern to generate an r-1-decay feeding current for displacing more water, indicating a trade-off among feeding, predator avoidance, and alga perception.
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Cruz-Rivera, E., and M. Friedlander. "Effects of algal phenotype on mesograzer feeding." Marine Ecology Progress Series 490 (September 17, 2013): 69–78. http://dx.doi.org/10.3354/meps10429.
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Al-Shaeri, Majed, Lynn Paterson, Margret Stobie, Paul Cyphus, and Mark G. J. Hartl. "Trophic Transfer of Single-Walled Carbon Nanotubes at the Base of the Food Chain and Toxicological Response." Nanomaterials 12, no. 24 (December 7, 2022): 4363. http://dx.doi.org/10.3390/nano12244363.
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The potential for trophic transfer of single-walled carbon nanotubes (SWCNTs) was assessed using the green algae Tetraselmis suecica and the blue mussel Mytilus edulis in a series of laboratory experiments. Swanee River Natural Organic Matter (SRNOM)-dispersed SWCNTs were introduced into growing algal cultures. Light microscopical observations, confirmed by scanning electronic microscopy (SEM) and Raman spectroscopy, showed that SWCNT agglomerates adhered to the external algal cell walls and transmission electronic microscopy (TEM) results suggested internalization. A direct effect of SWCNT exposure on the algae was a significant decrease in growth, expressed as chlorophyll a concentration and cell viability. Mussels, fed with algae in the presence of SWCNTs, led to significantly increased pseudofaeces production, indicating selective feeding. Nevertheless, histological sections of the mussel digestive gland following exposure showed evidence of SWCNT-containing algae. Furthermore, DNA damage and oxidative stress biomarker responses in the mussel haemocytes and gill tissue were significantly altered from baseline values and were consistent with previously observed responses to SWCNT exposure. In conclusion, the observed SWCNT-algal interaction demonstrated the potential for SWCNT entrance at the base of the food chain, which may facilitate their trophic transfer with potential consequences for human exposure and health.
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Drenner, Ray W., Stephen T. Threlkeld, and Michael D. McCracken. "Experimental Analysis of the Direct and indirect Effects of an Omnivorous Filter-Feeding Clupeid on Plankton Community Structure." Canadian Journal of Fisheries and Aquatic Sciences 43, no. 10 (October 1, 1986): 1935–45. http://dx.doi.org/10.1139/f86-239.
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In laboratory trials, feeding rates of an omnivorous filter-feeding clupeid, Dorosoma cepedianum, increased as a function of particle size, with maximal rates on microspheres, spherical algae, and Zooplankton >40 μm; it did not efficiently feed on filamentous Anabaena flos-aquae. To examine the community level impacts of Dorosoma, we conducted four seasonal outdoor tank experiments of cross-classified design involving two or three densities of Dorosoma and two densities of the zooplanktivorous atherinid fish, Menidia beryllina. We attempted to discriminate between the direct and indirect effects of Dorosoma on phytoplankton by using Menidia to produce indirect effects on phytoplankton by suppressing Zooplankton. Experiments began in November, March, June, and September and lasted for 45–53 d. Dorosoma suppressed most Zooplankton in at least one experiment and enhanced algal standing crops in all four experiments, as indicated by increased algal chlorophyll fluorescence, turbidity, Coulter counts and microscopic algal counts, and decreased Secchi depths. Because in three out of four experiments Menidia suppressed Zooplankton biomass to a greater extent than Dorosoma without enhancing phytoplankton, we reject the hypothesis that the enhancement of phytoplankton by Dorosoma was an indirect effect of Zooplankton biomass suppression.
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Korb, Rebecca. "Lack of dietary specialization in adult Aplysia californica: evidence from stable carbon isotope composition." Journal of the Marine Biological Association of the United Kingdom 83, no. 3 (April 9, 2003): 501–5. http://dx.doi.org/10.1017/s0025315403007422h.
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Natural abundance, 13C/12C ratios (δ13C) of Californian sea hares, Aplysia californica, (Gastropoda: Opisthobranchia) were measured for comparison with the animals preferred red algal diets, Plocamium cartilagineum and Laurenciapacifica. Isotopic compositions of animals collected from around Santa Catalina Island, did not reflect those of the favoured red algal diets, nor the majority of algal species found in the field. However, animals held in seawater tanks and fed diets with a constant carbon isotopic composition exhibited δ13C values similar to their food. Fast turnover tissue, such as the muscle tissue of actively growing juveniles or egg masses laid by adults, showed δ13C values within ±2‰ of the algal diet. Slow turnover tissue, such as the muscle tissue of large adults, reflected the diet over several months. Stable carbon isotope ratios thus proved a useful tool to clarify the extent to which specialized feeding in A. californica can occur upon algae which are only moderately to rarely common.
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Sattanathan, Govindharajan, Wen-Chao Liu, Swaminathan Padmapriya, Karthika Pushparaj, Shanmugam Sureshkumar, Jang-Won Lee, Balamuralikrishnan Balasubramanian, and In Ho Kim. "Effects of Dietary Blend of Algae Extract Supplementation on Growth, Biochemical, Haemato-Immunological Response, and Immune Gene Expression in Labeo rohita with Aeromonas hydrophila Post-Challenges." Fishes 8, no. 1 (December 22, 2022): 7. http://dx.doi.org/10.3390/fishes8010007.
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In this study, the effects of a mixed algal blend (Chlorella vulgaris, Euglena viridis, and Spirulina platensis) at different levels were evaluated on growth, hematological immune responses, and expression of immune genes in Labeo rohita against post-challenges of Aeromonas hydrophila. Fish samples were fed a diet containing different levels of mixed blend algal (0, 0.01, 0.02, 0.04 and 0.08% of basal diet). At the end of the feeding period, the fish were challenged with A. hydrophila and fish mortality was recorded over a 14-days period. To evaluate the serum biochemical (albumin, globulin), hematological parameters (Hb, RBC and WBC) and immune parameters (neutrophil activity, lysozyme activity, myeloperoxidase activity, antiprotease activity, ceruloplasmin activity, and bactericidal activity), as well as the expression of immune genes (NKEF-B, Lysozyme C and G, TNF α, TLR22, β2M, and β-actin), fish were sampled on Day 7, 14, 21 and 28. Fish were challenged with virulent A. hydrophila 30 days post-feeding and mortalities were recorded over 30 days post-infection. Results demonstrate that fish fed with a mixed algal blend showed that total body weight gain, specific growth rate, total serum protein, globulin, total hemoglobin content, white blood cells, neutrophil, lysozyme, bactericidal, myeloperoxidase, and antiprotease activity in dietary algae blended application was higher than in the control (p < 0.05). According to the results, relative expression of target genes showed significant increases of 0.02 to 0.04% in the treatment group compared to the control group (p < 0.05). At the end of the 30-day exposure to A. hydrophila, the fish that received the mixed algal blend had a significantly higher rate of survival than the control group, with the highest survival rate recorded in the 0.02% mixed algal blend (p < 0.05). According to the effective results of the mixed algal blend on stimulating the immune system and increasing fish resistance to A. hydrophila, it is recommended to use 0.02 to 0.04% of this mixed algal blend in rohu, L. rohita diets.
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Riisgård, Hans Ulrik, Parnuna P. Egede, and Isabel Barreiro Saavedra. "Feeding Behaviour of the Mussel,Mytilus edulis: New Observations, with a Minireview of Current Knowledge." Journal of Marine Biology 2011 (2011): 1–13. http://dx.doi.org/10.1155/2011/312459.
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Under optimal conditions, bivalves tend to filter the ambient water at a maximum rate but under suboptimal environmental conditions, including low or very high algal concentrations, the filtration rate is reduced. The upper algal concentration at which the blue mussel,Mytilus edulis, exploits its filtration capacity over an extended period of time was identified by stepwise raising the algal (Rhodomonas salina) concentration in steady-state experiments above the threshold for continuous high filtration rate. The duration time before incipient saturation reduction decreased with increasing algal concentration, and the threshold concentration for incipient saturation reduction of filtration activity was found to be between about 5,000 and 8,000 cells mL−1, equivalent to 6.3 and 10.0 μg chlaL−1, respectively. Reduced filtration rate was related to total number of algal cells ingested previous to incipient saturation and found to be cells. Video-microscope recordings of pseudofaeces production revealed that the trigger threshold concentration for formation of pseudofaeces was about 12,000 cells mL−1. Faeces produced by saturated mussels consisted of closely packed undigested algal cells, indicating severe overloading of the digestive system caused by high algal concentrations which mussels are not evolutionary adapted to cope with.
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Gilmour, T. H. J. "An analysis of videotape recordings of larval feeding in the sea urchin Lytechinus pictus (Verrill)." Canadian Journal of Zoology 63, no. 6 (June 1, 1985): 1354–59. http://dx.doi.org/10.1139/z85-203.
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Frame-by-frame analysis of videotapes of sea urchin larvae feeding on algal suspensions has shown that most algal cells entering the mouth are captured without reversal of the locomotory cilia. Low concentrations of the calcium blocker verapamil inhibit ciliary reversal without interfering with food capture, providing further evidence that reversals are of little significance in feeding. These observations suggest that the scan and trap theory of food capture does not apply to echinoderm larvae.
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Loria, Mark H., James S. Griffin, George F. Wells, and Kurt R. Rhoads. "Effects of feast-famine nutrient regimes on wastewater algal biofuel communities." PLOS ONE 18, no. 1 (January 4, 2023): e0279943. http://dx.doi.org/10.1371/journal.pone.0279943.
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Microalgae accumulate lipids in response to nutrient deprivation, and these lipids are a biodiesel fuel stock. Algal cultivation with secondary wastewater effluent is one proposed platform for biofuel production, which provides nutrients to algae while further polishing wastewater effluent. Algal bioreactors were tested using a feast-famine feeding regiment in simulated secondary wastewater effluent to evaluate the effects on lipid content and algal community structure. Algal polycultures were inoculated into reactors fed with synthetic secondary wastewater effluent at pH 7.5 and 9 and operated under a feast-famine nutrient (N, P, and BOD) supply regime in sequencing batch reactors. Fatty acid methyl ester contents of the reactors were assessed, which showed a decrease in lipid content after the feast-famine cycling (from 12.2% initially to 5.2% after four cycles at pH 9). This decrease in lipid content was not correlated with an increase in carbohydrate storage within biomass, nor an increase in bacterial biomass abundance relative to algal biomass in the reactors. The eukaryotic microbial communities from reactors operated at pH 9 diverged from reactors operated at pH 7.5 during cycling, with the pH 9 reactors becoming dominated by a single Operational Taxonomic Unit aligning to the Scenedesmus genus. These results suggest that high pH and feast-famine nutrient cycling may select for a less diverse algal community with a lower lipid content within a secondary wastewater polishing scheme.
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Costa, Diogo Fleury Azevedo, Joaquín Miguel Castro-Montoya, Karen Harper, Leigh Trevaskis, Emma L. Jackson, and Simon Quigley. "Algae as Feedstuff for Ruminants: A Focus on Single-Cell Species, Opportunistic Use of Algal By-Products and On-Site Production." Microorganisms 10, no. 12 (November 22, 2022): 2313. http://dx.doi.org/10.3390/microorganisms10122313.
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There is a wide range of algae species originating from a variety of freshwater and saltwater habitats. These organisms form nutritional organic products via photosynthesis from simple inorganic substances such as carbon dioxide. Ruminants can utilize the non-protein nitrogen (N) and the cell walls in algae, along with other constituents such as minerals and vitamins. Over recent decades, awareness around climate change has generated new interest into the potential of algae to suppress enteric methane emissions when consumed by ruminants and their potential to sequester atmospheric carbon dioxide. Despite the clear potential benefits, large-scale algae-livestock feedstuff value chains have not been established due to the high cost of production, processing and transport logistics, shelf-life and stability of bioactive compounds and inconsistent responses by animals under controlled experiments. It is unlikely that algal species will become viable ingredients in extensive grazing systems unless the cost of production and practical systems for the processing, transport and feeding are developed. The algae for use in ruminant nutrition may not necessarily require the same rigorous control during the production and processing as would for human consumption and they could be grown in remote areas or in marine environments, minimizing competition with cropping, whilst still generating high value biomass and capturing important amounts of atmospheric carbon. This review will focus on single-cell algal species and the opportunistic use of algal by-products and on-site production.
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Perevolotsky, Tal, Christopher H. Martin, Asaph Rivlin, and Roi Holzman. "Work that body: fin and body movements determine herbivore feeding performance within the natural reef environment." Proceedings of the Royal Society B: Biological Sciences 287, no. 1938 (November 11, 2020): 20201903. http://dx.doi.org/10.1098/rspb.2020.1903.
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Herbivorous fishes form a keystone component of reef ecosystems, yet the functional mechanisms underlying their feeding performance are poorly understood. In water, gravity is counter-balanced by buoyancy, hence fish are recoiled backwards after every bite they take from the substrate. To overcome this recoil and maintain contact with the algae covered substrate, fish need to generate thrust while feeding. However, the locomotory performance of reef herbivores in the context of feeding has hitherto been ignored. We used a three-dimensional high-speed video system to track mouth and body kinematics during in situ feeding strikes of fishes in the genus Zebrasoma , while synchronously recording the forces exerted on the substrate. These herbivores committed stereotypic and coordinated body and fin movements when feeding off the substrate and these movements determined algal biomass removed. Specifically, the speed of rapidly backing away from the substrate was associated with the magnitude of the pull force and the biomass of algae removed from the substrate per feeding bout. Our new framework for measuring biting performance in situ demonstrates that coordinated movements of the body and fins play a crucial role in herbivore foraging performance and may explain major axes of body and fin shape diversification across reef herbivore guilds.
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Van Alstyne, KL, JM Ehlig, and SL Whitman. "Feeding preferences for juvenile and adult algae depend on algal stage and herbivore species." Marine Ecology Progress Series 180 (1999): 179–85. http://dx.doi.org/10.3354/meps180179.
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Vázquez-Luis, Maite, Pablo Sanchez-Jerez, and Just T. Bayle-Sempere. "Does the invasion ofCaulerpa racemosavar.cylindraceaaffect the feeding habits of amphipods (Crustacea: Amphipoda)?" Journal of the Marine Biological Association of the United Kingdom 93, no. 1 (April 19, 2012): 87–94. http://dx.doi.org/10.1017/s0025315412000288.
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Ecological interactions involving introduced seaweeds constitute an important research gap, since they could alter the trophic dynamics of native populations, but indirect effects on trophic levels are poorly known. The seaweedCaulerpa racemosais one of the most notable invaders in the Mediterranean Sea. It is well known thatC. racemosamodifies the amphipod community with respect to native habitats, but nothing is known regarding the common use of the same trophic resources. Therefore, the aim of this study was to assess if the feeding habits of amphipods associated with algal habitats are affected by the spread of the invasiveC. racemosa, through stomach content analysis of amphipods living in both native and invaded seaweed assemblages. A total of 240 specimens of 14 species of amphipods were examined. Ten species were present in both studied habitats (native and invaded), while two were exclusive to native and invaded habitats, respectively. Ten individuals of each species at each habitat were selected and their gut contents were examined. A total of 11 different items was found in the gut contents: detritus; vegetal detritus; algae; animal tissue; Oligochaeta; Polychaeta; Foraminifera; Crustacea; Sipuncula; diatoms; and non-identified items. The expansion ofC. racemosainto the native algal community changes the feeding habits of herbivorous amphipods, since their preferred food (epiphytic algae) is not available in the new habitat produced byC. racemosa. This community change occurs because of the presence of caulerpenyne inC. racemosa, which retards the growth of epiphytic algae. Nevertheless, other species are not affected or benefited by the invasion, such as detritivorous species whose main food source and habitat remains available. Altogether, slight changes in the trophodynamism of amphipod assemblages have been detected, which are not seen as relevant in an initial stage. However, they might be promoting some indirect effects in the energetic budget of populations, which may affect the life history. Further studies on food-web interactions in the ecosystems affected by invasive species are necessary.
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Zhang, Xue, Hong-Ying Hu, and Yu Hong. "Primary study on the feeding characteristics of a golden alga on Microcystis aeruginosa." Water Science and Technology 59, no. 9 (May 1, 2009): 1727–32. http://dx.doi.org/10.2166/wst.2009.200.
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A flagellate Jin821 which could feed on toxic cyanobacteria Microcystis aeruginosa was isolated, and it was identified as a species of golden alga according to its morphological characters and 18S rDNA genes. The results of feeding experiments showed that the golden alga Jin821 could make the high density (4.3 × 106 cells·mL−1) of M. aeruginosa clear in a short time (40 h), with a removal rate of 99.9%. And the microcystin (MC-LR) was also degraded effectively at the same time, with a removal rate of 82.7% of 114 μg/L in 40 h. The growth curve of Jin821 was in ‘S’ style, with four phases of lag, log, stationary and decline. When M. aeruginosa was cleaned out, Jin821 would decline in number and slowed down in movement. In summary, the golden alga Jin821 can be a potential biological way to control blue algal blooms in the future.
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Louhi, Pauliina, John S. Richardson, and Timo Muotka. "Sediment addition reduces the importance of predation on ecosystem functions in experimental stream channels." Canadian Journal of Fisheries and Aquatic Sciences 74, no. 1 (January 2017): 32–40. http://dx.doi.org/10.1139/cjfas-2015-0530.
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Sedimentation is a pervasive cause of biological impairment in streams, and predation exerts strong control over lower trophic levels. However, studies combining these two factors are lacking. In a factorial experiment in flow-through channels, addition of sand (<0.5 mm) and predatory stoneflies (Perlidae) caused independent effects on benthic invertebrates, algal biomass, and leaf breakdown. Sand reduced invertebrate density by 55% and also reduced leaf breakdown and algal biomass. Predators reduced invertebrate densities by 40%, with the strongest impact on algal-feeding invertebrates. Predators also decreased densities of leaf-shredding invertebrates and reduced leaf breakdown, thereby inducing a trophic cascade via detritus-based food web. The two treatments exhibited an antagonistic interaction whereby sand obscured any effect of predators on algae, indicating that an abiotic stress may modify a trophic cascade. By contrast, we found no support for synergistic interactions between sand and predation. The strong effects of sedimentation on key ecosystem processes illustrate that stream management needs to exploit riparian and in-stream measures to reduce sediment inputs to headwater streams.
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Hallegraeff, Gustaaf, and Christopher Bolch. "Unprecedented toxic algal blooms impact on Tasmanian seafood industry." Microbiology Australia 37, no. 3 (2016): 143. http://dx.doi.org/10.1071/ma16049.
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While most microscopic algae provide food for filter-feeding shellfish and larvae of crustaceans and finfish, other so-called Harmful Algal Blooms (HABs) can have negative effects, causing severe economic losses to aquaculture, fisheries and tourism. Of greatest concern to human society are blooms of toxic HAB species that cause illness and death of fish, seabirds and mammals via toxins transferred through the food web. Unprecedented Alexandrium (Dinophyceae) blooms along the East Coast of Tasmania in 2012 and 2015, a previously low biotoxin risk area, led to major impacts on the local oyster, mussel, scallop and rock lobster industries. Four human hospitalisations also occurred from eating wild shellfish.
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Nichols, S. J., and D. Garling. "Food-web dynamics and trophic-level interactions in a multispecies community of freshwater unionids." Canadian Journal of Zoology 78, no. 5 (May 1, 2000): 871–82. http://dx.doi.org/10.1139/z99-256.
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We compared feeding habits and trophic-level relationships of unionid species in a detritus-dominated river and an alga-dominated lake using biochemical analyses, gut contents, and stable-isotope ratios. The δ13C ratios for algae and other food-web components show that all unionids from both the river and the lake used bacterial carbons, not algal carbons, as their main dietary source, in spite of positive selection and concentration of diatoms and green algae from the water column in the gut and mantle cavity. Algae did provide key nutrients such as vitamins A and D and phytosterols that were bioaccumulated in the tissues of all species. The δ15N ratios for the multispecies unionid community in the Huron River indicated some differences in nitrogen enrichment between species, the greatest enrichment being found in Pyganadon grandis. These δ15N ratios indicate that unionids may not always feed as primary consumers or omnivores. Stable-isotope data were critical for delineating diets and trophic-level interactions of this group of filter-feeders. Further refinements in identifying bacterial and picoplankton components of the fine particulate organic matter are needed to complete our understanding of resource partitioning between multispecies unionid populations.
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Cummings, D. O., and J. E. Williamson. "The role of herbivory and fouling on the invasive green alga Caulerpa filiformis in temperate Australian waters." Marine and Freshwater Research 59, no. 4 (2008): 279. http://dx.doi.org/10.1071/mf06238.
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The green macroalga Caulerpa filiformis is rapidly dominating algal assemblages in shallow subtidal regions along the New South Wales (NSW) coast. Given that invasive species are known for their competitive superiority, the interactions between C. filiformis and herbivores and fouling species was investigated and were compared with those co-occurring native species. Extensive field surveys were carried out to assess purported damage from herbivores, and co-occurrence of C. filiformis with herbivorous fish and invertebrate species. Signs of herbivory on C. filiformis were visible, and several common herbivorous invertebrates and fish co-occurred with the alga. Laboratory and field feeding assays with fresh algae indicated that generalist invertebrate herbivores such as Turbo torquatus did not consume C. filiformis, whereas herbivorous fish did consume C. filiformis but not in preference to other palatable algae. C. filiformis was fouled at similar concentrations and with similar epiphytic species to other co-occurring algae. Thus the ability of C. filiformis to deter herbivory and fouling by using biotic deterrents (both chemical and structural) is limited and unlikely to be the major factor driving its successful invasion into NSW habitats.
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Norman, Mitch, Zachary E. Carlson, Fred H. Hilscher, Galen E. Erickson, Bruce Brodersen, John Loy, Jonathan Wilson, Christian Rabe, and Andrea K. Watson. "341 Evaluation of the safety of an algal biomass as an ingredient in finishing cattle diets." Journal of Animal Science 97, Supplement_2 (July 2019): 137–38. http://dx.doi.org/10.1093/jas/skz122.244.
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Abstract Algae production is increasing to supply the growing demand for Omega-3 fatty acids for aquaculture, human food and pet food; co-products from the algae industry could be a suitable feed ingredient for cattle feeding. A safety study was conducted to evaluate feeding algal biomass to cattle. Crossbreed cattle (20 steers and 20 heifers, 255 kg initial BW, SD=14) were individually fed 4 inclusions of condensed algal residue solubles (CARS; 0, 2.5, 5, 7.5 % of diet DM) displacing dry rolled corn in a finishing diet (62.5 to 70% corn and 15% distillers grains) for a minimum of 97 d. At harvest, organs were weighed and sampled. Blood was collected every 30 d. Performance data were analyzed as a RCBD with treatment, gender, and treatment by gender interactions as fixed effects, BW block as a random effect and individual animal as the experimental unit. Orthogonal contrasts were used to test for linear, quadratic and cubic responses due to CARS inclusion. Increasing CARS in the diet quadratically increased DMI and ADG (P ≤ 0.01). A linear increase was observed for G:F, NEm,and NEg as CARS increased in the diet (P < 0.01). All organ weights measured were within expected ranges for cattle, with 6 out of 27 having differences in weight due to treatment (P ≤ 0.05). Histopathology analysis of organs revealed no differences due to treatment (P ≥ 0.24). Out of 21 blood chemistry measures, 8 were affected by treatment (P ≤ 0.02). Nearly all blood chemistry parameters were within expected ranges for cattle. No adverse effects of feeding CARS were observed in hematology, blood chemistry, or histopathology analyses. The feedstuff CARS demonstrated to be a safe and efficacious feed ingredient for cattle diets and maximized HCW, ADG, and DMI when fed at 2.5 or 5% of the diet.
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McAuley, P. J., and L. Muscatine. "The cell cycle of symbiotic Chlorella. IV. DNA content of algae slowly increases during host starvation of green hydra." Journal of Cell Science 85, no. 1 (September 1, 1986): 73–84. http://dx.doi.org/10.1242/jcs.85.1.73.
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The distribution of DNA content of symbiotic Chlorella algae freshly isolated from green hydra was compared with that of cultured Chlorella of the NC64A strain, using flow cytometry. In nonlogarithmic cultures of NC64A most cells had accumulated in G1 phase, while in logarithmic cultures a peak containing cells in S phase and mitosis could be distinguished from the larger G1 peak. However, symbiotic algae showed a single broad peak in which there was no clear distinction between G1 and S phase/mitosis. When hydra were starved for a prolonged period, inhibiting host cell and algal division, the DNA content of the symbiotic algae slowly increased, and the number of daughter cells produced after a single feeding increased with the length of the preceding period of starvation. This suggests that symbiotic algae are able to cycle slowly through S phase, but unless the host is fed they cannot traverse into mitosis and complete the cell division cycle. No significant difference in cell size was found between algae producing either four or eight daughter cells after 1-day- or 22-day-starved hydra were fed, suggesting that algal cell size did not determine the number of daughter cells produced. Instead, this may be dependent upon the length of time the cell had spent in S phase prior to receiving the, as yet unknown, stimulus to enter into mitosis.
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Monteiro, Marta, Carla Sousa, Filipe Coutinho, Carolina Castro, Filipa Fontinha, Inês Guerreiro, Pedro Pousão, et al. "Functional Feeds to Tackle Meagre (Argyrosomus regius) Stress: Physiological Responses under Acute Stressful Handling Conditions." Marine Drugs 19, no. 11 (October 21, 2021): 598. http://dx.doi.org/10.3390/md19110598.
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Marine algae are recognised sources of bioactive compounds that have attracted great interest as nutritional supplements for aquaculture fish. Intensive rearing conditions often expose fish to husbandry-related stressors, rendering fish more susceptible to disease and reducing production yields. The present work evaluated the potential of two marine algae extracts (Fucus vesiculosus and Nannochloropsis gaditana) as nutritional supplements to mitigate stress effects in meagre (Argyrosomus regius) exposed to an acute handling stress (AS). A plant-based diet was used as a control, and three other diets were prepared, which were similar to the control diet but supplemented with 1% of each algal extract or a combination of the two extracts (0.5% each). The effects of supplemented diets on stress biomarkers, antioxidant enzyme activities, and immune response were analysed in fish exposed to AS after 4 weeks of feeding. Supplemented diets did not affect growth performance but the inclusion of F. vesiculosus promoted higher feed efficiency, as compared to the control group. Dietary algal extracts supplementation reduced plasma glucose levels, increased white blood cell counts, and reduced the expression of pro-inflammatory genes when compared with the control. N. gaditana supplementation led to a reduction in hepatic antioxidant enzyme activity and glutathione levels, while F. vesiculosus supplementation increased muscle glutathione reductase activity and reduced lipid peroxidation. These findings support the potential of algal extracts as nutraceuticals in aquafeeds to enhance the ability of fish to cope with husbandry-related stressful conditions and ultimately improve fish health and welfare.
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Ruas, Graziele, Sarah Farias Lacerda, Maria Alice Nantes, Mayara Leite Serejo, Gustavo Henrique Ribeiro da Silva, and Marc Árpad Boncz. "CO2 Addition and Semicontinuous Feed Regime in Shaded HRAP—Pathogen Removal Performance." Water 14, no. 24 (December 12, 2022): 4047. http://dx.doi.org/10.3390/w14244047.
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The influence of CO2 addition and feeding regime (continuous versus semicontinuous) on the removal of Pseudomonas aeruginosa, Clostridium perfringens, Staphylococcus, Enterococcus faecalis, and Escherichia coli (E. coli) from three shaded high-rate algal ponds (HRAPs) treating raw sewage (RS) was studied. The three HRAPs were operated at an analogous hydraulic retention time (HRT) for 5 days and with shading of 50%. The CO2 addition and feeding regime had no statistically significant influence on the removal of Pseudomonas aeruginosa, Clostridium perfringens, Staphylococcus sp., and Enterococcus faecalis, with 2.39–3.01, 2.07–2.31, 3.02–3.38, and 3.14–3.45 log units, respectively. However, the removal of E. coli decreased significantly with the feeding regime of 0.1 h d−1 and 2.23–3.29 log units. The productivity and the total suspended solids (TSS) removal efficiency were significantly improved with the semicontinuous feeding regime and CO2 addition. The highest productivity was obtained in the semicontinuous feeding regime, 5.93 g m2 d−1, while the TSS removal efficiency was similar between the semicontinuous feeding regime and CO2 addition (31–36%). The control of light intensity led to greater variability in the algal community, and was present in the three reactors, in different proportions, in the form of the microalgae Scenedesmus acutus, Scenedesmus obliquus, and Chlorella sp.
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Görgényi, Judit, Gergely Boros, Zoltán Vitál, Attila Mozsár, Gábor Várbíró, Gábor Vasas, and Gábor Borics. "The role of filter-feeding Asian carps in algal dispersion." Hydrobiologia 764, no. 1 (May 6, 2015): 115–26. http://dx.doi.org/10.1007/s10750-015-2285-2.
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Sakata, K., K. Kato, Y. Iwase, H. Okada, K. Ina, and Y. Machiguchi. "Feeding-stimulant activity of algal glycerolipids for marine herbivorous gastropods." Journal of Chemical Ecology 17, no. 1 (January 1991): 185–93. http://dx.doi.org/10.1007/bf00994432.
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Hartmann, Hans J., Hassan Taleb, Lotfi Aleya, and Nicole Lair. "Predation on Ciliates by the Suspension-Feeding Calanoid Copepod Acanthodiaptomus denticornis." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 7 (July 1, 1993): 1382–93. http://dx.doi.org/10.1139/f93-158.
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The effects of prey size, hunger, and algal presence on the predation of the suspension-feeding calanoid copepod Acanthodiaptomus denticornis on the ciliates Tetrahymena corlisii (32 μm mean length), Paramecium aurelia (114 μm), P. caudatum (124 μm), Loxodes sp. [Formula: see text], and Stentor coeruleus[Formula: see text] and the flagellate Astasia longa (14 μm) were evaluated in laboratory experiments. Adult Acanthodiaptomus consumed all species, but not in proportion to their size. At low concentrations (prey < 200 μg C∙L−1), mean clearance rates ranged from 80 mL∙copepod−1∙d−1 (for Paramecium) to 13 mL∙copepod−1∙d−1 (for Loxodes). Clearance rates declined with increasing concentration of the same prey, as expected. Prey capture and ingestion was determined by cell width and prey escape reactivity. Hunger significantly increased predation rates at high prey levels. The presence of algae enhanced ciliate predation by hungry copepods at low prey levels, but had no other significant effects. Protozoan predation by Acanthodiaptomus generally exceeds its feeding on algae and nanoplankton. Results suggest that ciliates can be a significant part of the diet of some suspension-feeding freshwater copepods in situ, confirming the importance of ciliates as mediators of energy transfer from the microbial loop to higher trophic levels.
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Das, Indraneil. "The internal oral morphology of some anuran larvae from south India: a scanning electron microscopic study." Amphibia-Reptilia 15, no. 3 (1994): 249–56. http://dx.doi.org/10.1163/156853894x00029.
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AbstractThe internal oral morphology of the larvae of four species of sympatric anuran amphibians from a locality in south India was examined by scanning electron microscopy. A close fit between diet and oral structures was found. The mouthparts are considerated as adaptive for a variety of feeding modes, including filter-feeding, algal-scraping and macrophyte-snipping.
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Reis Costa. "Advances and Current Challenges in Marine Biotoxins Monitoring." Journal of Marine Science and Engineering 7, no. 9 (September 2, 2019): 302. http://dx.doi.org/10.3390/jmse7090302.
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Papadakis, O., K. Tsirintanis, V. Lioupa, and S. Katsanevakis. "The neglected role of omnivore fish in the overgrazing of Mediterranean rocky reefs." Marine Ecology Progress Series 673 (September 2, 2021): 107–16. http://dx.doi.org/10.3354/meps13810.
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Sea urchins are considered the most important grazers in Mediterranean shallow sublittoral rocky reef ecosystems, but fish can also have an important role in overgrazing and the reduction of habitat complexity. In this study, the trophic behavior of fish was recorded when provided access to experimental surfaces with increased macroalgal biomass and associated benthic fauna, created by herbivore exclusion cages. After a sufficient period for substantial algal growth, the cages were removed and the activity of fish on these surfaces was recorded for 3 h by an automated photographic camera system. Control surfaces with no restriction on grazers were defined on similar substrates for comparison. To quantify the effects of fish feeding activity on macroalgal coverage, photographic samples were taken immediately after the opening of the cages and after each 3 h recording. The response of fish when the cages were removed was immediate and intense. Feeding activity by 13 different fish species was recorded in total, of which the most frequent were the omnivores Diplodus vulgaris, Coris julis and Thalassoma pavo, and to a lesser extent the herbivore Sarpa salpa. The coverage of erect algae was substantially decreased on the experimental surfaces due to fish feeding activity. The algae were either directly consumed by the fish or cut off when the fish were feeding on macroinvertebrates. We conclude that in addition to grazing by herbivores, fish of higher trophic levels can also significantly affect macroalgal assemblages and restrict the recovery of erect algae in overgrazed reefs where prey is scarce.
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Queiroz, RNM, and TLP Dias. "Molluscs associated with the macroalgae of the genus Gracilaria (Rhodophyta): importance of algal fronds as microhabitat in a hypersaline mangrove in Northeastern Brazil." Brazilian Journal of Biology 74, no. 3 suppl 1 (August 2014): S052—S063. http://dx.doi.org/10.1590/1519-6984.20712.
Full textAbstract:
The fronds of marine macroalgae play an important role in coastal ecosystems because the algae banks are utilized as a microhabitat by different taxa, including molluscs, one of the most abundant and diverse animals of marine ecosystems. In this study, we characterized the malacofauna associated with the macroalgae Gracilaria domingensis (Kützing) Sonder ex Dickie 1874 and Gracilaria cuneata Areschoug 1854 of a hypersaline mangrove on the northern coast of the state of Rio Grande do Norte, Northeastern Brazil. The first alga dominates in the rainy season and it is substituted by second one in the dry period. A total of 1,490 molluscs were surveyed, representing 56 species in 29 families: 1,081 were associated with G. domingensis and 409 with G. cuneata, the latter showing the greater diversity (H′=1.25). Columbellidae, Neritidae, Pyramidellidae and Cerithiidae were among the most representative families in the number of species and individuals. The micromolluscs were dominant in the algal microhabitat, constituting 74.63% of the malacofauna recorded. The columbellid Parvanachis obesa(C. B. Adams, 1845) was the dominant species followed by the neritid Neritina virginea (Linnaeus, 1758) in both algae. In spite of the annual alternated succession of the algae species, at least 15 mollusc species are common for these algae. Furthermore, juveniles of P. obesa were recorded in both seasons, indicating a continuous reproduction. Possible reasons for difference in abundance, diversity and dominance of molluscs living on these algae are discussed. Both species of substrate-algae represent an important microhabitat for refuge, feeding and the reproduction of small-sized mollusc species during rainy and dry seasons.
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Crisp, D. J., A. B. Yule, and K. N. White. "Feeding By Oyster Larvae: The Functional Response, Energy Budget and A Comparison With Mussel Larvae." Journal of the Marine Biological Association of the United Kingdom 65, no. 3 (August 1985): 759–83. http://dx.doi.org/10.1017/s0025315400052589.
Full textAbstract:
Whereas there is a wealth of literature on the feeding of herbivorous holo-plankton, notably copepods, feeding by herbivorous larvae of benthic animals has been somewhat neglected. This paper considers the functional feeding response of veliger larvae of Ostrea edulis L., Crassostrea gigas (Thunberg) and Mytilus edulis L. fed on several micro-algal species. It also provides some data on the influence of temperature on feeding, and assesses the energy needs of the larvae in relation to their potential ingestion rate and to the availability in the sea of micro-organisms on which they feed.
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Brand-Gardner, S. J., C. J. Limpus, and J. M. Lanyon. "Diet selection by immature green turtles, Chelonia mydas, in subtropical Moreton Bay, south-east Queensland." Australian Journal of Zoology 47, no. 2 (1999): 181. http://dx.doi.org/10.1071/zo98065.
Full textAbstract:
Diet selection by immature green turtles (Chelonia mydas) in Flathead Gutter, Moreton Bay, was determined by examining food ingested in relation to food availability (measured as vegetation composition and abundance within the feeding site). Food composition was sampled by oesophageal lavage. Turtles were repeatedly located over a 10-week period by means of sonic telemetry and visual identification. The number of resightings indicated that these turtles remained within their feeding grounds for at least short periods of time. Immature green turtles fed on both seagrass and algal species. However, most fed selectively on algae, primarily Gracilaria sp. Food items consumed frequently by these turtles were analysed for total nitrogen, gross energy and neutral detergent fibre levels. There was a negative correlation between fibre level and the preferred food species, where the more frequently selected species had lower levels of fibre. The preferred species also had higher nitrogen levels
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Gutow, Lars, Alistair G. B. Poore, Manuel A. Díaz Poblete, Vieia Villalobos, and Martin Thiel. "Small burrowing amphipods cause major damage in a large kelp." Proceedings of the Royal Society B: Biological Sciences 287, no. 1926 (April 29, 2020): 20200330. http://dx.doi.org/10.1098/rspb.2020.0330.
Full textAbstract:
Large herbivores such as sea urchins and fish consume a high proportion of benthic primary production and frequently control the biomass of marine macrophytes. By contrast, small mesograzers, including gastropods and peracarid crustaceans, are abundant on seaweeds but have low per capita feeding rates and their impacts on marine macrophytes are difficult to predict. To quantify how mesograzers can affect macrophytes, we examined feeding damage by the herbivorous amphipods Sunamphitoe lessoniophila and Bircenna sp., which construct burrows in the stipes of subtidal individuals of the kelp Lessonia berteroana in northern-central Chile, southeast Pacific. Infested stipes showed a characteristic sequence of progressive tissue degeneration. The composition of the amphipod assemblages inside the burrows varied between the different stages of infestation of the burrows. Aggregations of grazers within burrows and microhabitat preference of the amphipods result in localized feeding, leading to stipe breakage and loss of substantial algal biomass. The estimated loss of biomass of single stipes varied between 1 and 77%. For the local kelp population, the amphipods caused an estimated loss of biomass of 24–44%. Consequently, small herbivores can cause considerable damage to large kelp species if their feeding activity is concentrated on structurally valuable algal tissue.
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Sautour, Benoît, and Jacques Castel. "Grazing activity of mesoplanktonic copepods in a shallow bay during an algal spring bloom (Marennes-Oléron Bay, France)." Journal of the Marine Biological Association of the United Kingdom 79, no. 1 (February 1999): 73–84. http://dx.doi.org/10.1017/s0025315498000083.
Full textAbstract:
In situ grazing activity of mesoplanktonic copepods was investigated by the fluorometric method during an algal spring bloom in a zone of oyster farming in Marennes-Oléron Bay. The grazing activity of copepods was overall higher during the night than during the day for three species (Temora longicornis, Paracalanus parvus and Acartia clausi), but peaks also appeared during the day for all of them. Individual ingestion rates and daily rations were higher during neap tide (low suspended particulate matter (SPM) concentrations) than during spring tide (high SPM concentrations). During ebb tide (when SPM concentrations were the lowest) the feeding activity of T. longicornis, P. parvus and A. clausi was significantly negatively correlated with algal concentration. Our work suggests that during the algal spring bloom in the farming area of Marennes-Oléron Bay the pressure exerted by mesoplanktonic copepods on the algal stock was very low, as a consequence of: (i) high algal concentrations in the field (resuspension and high phytoplanktonic production); (ii) low ingestion rates when high algal concentrations were observed. The likely ingestion of non-fluorescent particles by copepods is discussed.
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Nauroth, Julie Marie, Mary Van Elswyk, Ying Liu, and Linda Arterburn. "Anti-inflammatory activity of algal oils containing Docosahexaenoic Acid (DHA) and omega-6 Docosapentaenoic Acid (DPAn-6) (101.5)." Journal of Immunology 178, no. 1_Supplement (April 1, 2007): S201. http://dx.doi.org/10.4049/jimmunol.178.supp.101.5.
Full textAbstract:
Abstract Background: Studies have shown anti-inflammatory activity associated with fish oil and ascribed this effect to the long-chain omega-3 fatty acids DHA and especially eicosapentaenoic acid (EPA). Objective: The purpose of this study was to examine the anti-inflammatory effects of DHA-rich algal oils which contain little or no EPA and determine the contribution of their individual constituent fatty acids, particularly DHA and DPAn-6. Results: The effects of feeding DHA-rich Martek DHA-T™ algal oil and DHA/DPAn-6-rich Martek DHA-S™ algal oil on rat carrageenan-induced hind paw edema was examined. The S-oil was more effective at reducing edema than the T-oil, suggesting that DPAn-6 has anti-inflammatory properties. We next tested the in vitro effects of the individual pure fatty acids on reducing LPS-stimulated IL-1β and TNF-α secretion by human peripheral blood mononuclear cells. The relative potency was DPAn-6 (most potent) > DHA > EPA. All three fatty acids were effective at reducing by >50% neutrophil fMLP-mediated migration in vitro. Further in vivo analyses demonstrated that feeding pure DHA and EPA ethyl esters (EE) reduced paw edema and the combination of DHA/DPAn6-EE which mimics algal oil was more potent than the combination of DHA/EPA-EE which mimics fish oil. Conclusions: DHA, DPAn-6, and EPA have anti-inflammatory activity in vitro and in vivo. Algal S-oil containing the combination of DHA and DPAn-6 shows potential for use in anti-inflammatory applications.