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1

Lenzo, Denise, Marina Antonia Colangelo, Andrea Pasteris, Fabio Rindi, Rossella Pistocchi e Laura Pezzolesi. "Understanding the Role of Macroalgal Complexity and Allelochemicals Production in Invasive and Non-Invasive Macroalgae in the North-Western Adriatic Sea: Effect on the Associated Communities". Water 15, n. 9 (27 aprile 2023): 1697. http://dx.doi.org/10.3390/w15091697.

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Highly diverse microphyto and meiobenthic communities are associated with large-sized marine macroalgae. Both morphological traits and allelochemical responses of macroalgae affect the composition of these communities, but the relative importance of these factors remains incompletely understood. In this study we investigated the microphytobenthic and meiobenthic communities associated with some native macroalgae and a non-indigenous species (Sargassum muticum) of the north-western Adriatic Sea. These seaweeds were sampled in two coastal sites subjected to different impacts. The possible effects of the structural complexity of the macroalgae and the potential role of allelochemicals (specifically polyunsaturated aldehydes, PUAs) on the associated communities were examined using univariate and multivariate analyses. The results indicate that distinct assemblages were associated with the macroalgae collected at the two different sites. Differences in microphytobenthic communities could be ascribed to differences in the macroalgal morphological traits and in their PUAs production. Conversely, variation of the meiobenthic community seemed to be related mainly to differences in the macroalgal communities at the two sites. This apparent inconsistency between the two analyzed communities suggests that microphytobenthos and meiofauna were differently shaped by the environmental habitat provided by macroalgae in the two sites, that are subjected to different environmental conditions and human activities. Overall, these results indicate that interactions between organisms belonging to different trophic groups (e.g., microphytobenthos and meiofauna) should be investigated in detail to better understand the global role of macroalgae as habitat formers on coastal ecosystems, especially in the case of large-sized introduced species.
2

Clements, Cody S., e Mark E. Hay. "Competitors as accomplices: seaweed competitors hide corals from predatory sea stars". Proceedings of the Royal Society B: Biological Sciences 282, n. 1814 (7 settembre 2015): 20150714. http://dx.doi.org/10.1098/rspb.2015.0714.

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Indirect biotic effects arising from multispecies interactions can alter the structure and function of ecological communities—often in surprising ways that can vary in direction and magnitude. On Pacific coral reefs, predation by the crown-of-thorns sea star, Acanthaster planci , is associated with broad-scale losses of coral cover and increases of macroalgal cover. Macroalgal blooms increase coral–macroalgal competition and can generate further coral decline. However, using a combination of manipulative field experiments and observations, we demonstrate that macroalgae, such as Sargassum polycystum , produce associational refuges for corals and dramatically reduce their consumption by Acanthaster . Thus, as Acanthaster densities increase, macroalgae can become coral mutualists, despite being competitors that significantly suppress coral growth. Field feeding experiments revealed that the protective effects of macroalgae were strong enough to cause Acanthaster to consume low-preference corals instead of high-preference corals surrounded by macroalgae. This highlights the context-dependent nature of coral–algal interactions when consumers are common. Macroalgal creation of associational refuges from Acanthaster predation may have important implications for the structure, function and resilience of reef communities subject to an increasing number of biotic disturbances.
3

Briggs, Amy A., Anya L. Brown e Craig W. Osenberg. "Local versus site-level effects of algae on coral microbial communities". Royal Society Open Science 8, n. 9 (settembre 2021): 210035. http://dx.doi.org/10.1098/rsos.210035.

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Microbes influence ecological processes, including the dynamics and health of macro-organisms and their interactions with other species. In coral reefs, microbes mediate negative effects of algae on corals when corals are in contact with algae. However, it is unknown whether these effects extend to larger spatial scales, such as at sites with high algal densities. We investigated how local algal contact and site-level macroalgal cover influenced coral microbial communities in a field study at two islands in French Polynesia, Mo'orea and Mangareva. At 5 sites at each island, we sampled prokaryotic microbial communities (microbiomes) associated with corals, macroalgae, turf algae and water, with coral samples taken from individuals that were isolated from or in contact with turf or macroalgae. Algal contact and macroalgal cover had antagonistic effects on coral microbiome alpha and beta diversity. Additionally, coral microbiomes shifted and became more similar to macroalgal microbiomes at sites with high macroalgal cover and with algal contact, although the microbial taxa that changed varied by island. Our results indicate that coral microbiomes can be affected by algae outside of the coral's immediate vicinity, and local- and site-level effects of algae can obscure each other's effects when both scales are not considered.
4

Li, Xunmeng, Jianqu Chen, Jun Li, Kai Wang, Zhenhua Wang e Shouyu Zhang. "Determination of intertidal macroalgae community patterns using the power law model". PLOS ONE 17, n. 11 (7 novembre 2022): e0277281. http://dx.doi.org/10.1371/journal.pone.0277281.

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The spatial heterogeneity of macroalgae in intertidal zones affects the stability of marine ecosystem communities, contributes to the maintenance of coastal biodiversity, and has an essential role in ecosystem and habitat maintenance. We explored the feasibility of applying the power law model to analyze the spatial distribution of macroalgae on Lvhua Island (Zhejiang Province, China) and characterized the intertidal spatial heterogeneity of the macroalgae present. The results showed a strong association between the spatial distribution of macroalgae in the intertidal zone and the power law model (R2 = 0.98). There was a positive association between species occurrence frequency and the spatial heterogeneity index of macroalgae species. The model also indicated there was macroalgal habitat structure at the site as the spatial heterogeneity within the community was greater than that of random distribution. The power law model reported here provides a new method for macroalgae community ecology research and could be broadly utilized to analyze the spatial pattern of macroalgae in intertidal zones.
5

Duran, Alain, Ligia Collado-Vides e Deron E. Burkepile. "Seasonal regulation of herbivory and nutrient effects on macroalgal recruitment and succession in a Florida coral reef". PeerJ 4 (2 novembre 2016): e2643. http://dx.doi.org/10.7717/peerj.2643.

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Herbivory and nutrient enrichment are drivers of benthic dynamics of coral reef macroalgae; however, their impact may vary seasonally. In this study we evaluated the effects of herbivore pressure, nutrient availability and potential propagule supply on seasonal recruitment and succession of macroalgal communities on a Florida coral reef. Recruitment tiles, replaced every three months, and succession tiles, kept in the field for nine months, were established in an ongoing factorial nutrient enrichment-herbivore exclusion experiment. The ongoing experiment had already created very different algal communities across the different herbivory and nutrient treatments. We tracked algal recruitment, species richness, and species abundance through time. Our results show seasonal variation in the effect of herbivory and nutrient availability on recruitment of coral reef macroalgae. In the spring, when there was higher macroalgal species richness and abundance of recruits, herbivory appeared to have more control on macroalgal community structure than did nutrients. In contrast, there was no effect of either herbivory or nutrient enrichment on macroalgal communities on recruitment tiles in cooler seasons. The abundance of recruits on tiles was positively correlated with the abundance of algal in the ongoing, established experiment, suggesting that propagule abundance is likely a strong influence on algal recruitment and early succession. Results of the present study suggest that abundant herbivorous fishes control recruitment and succession of macroalgae, particularly in the warm season when macroalgal growth is higher. However, herbivory appears less impactful on algal recruitment and community dynamics in cooler seasons. Ultimately, our data suggest that the timing of coral mortality (e.g., summer vs. winter mortality) and freeing of benthic space may strongly influence the dynamics of algae that colonize open space.
6

Doi, Hideyuki, Masatoshi Matsumasa, Mamoru Fujikawa, Keiichi Kanou, Takao Suzuki e Eisuke Kikuchi. "Macroalgae and seagrass contribution to gastropods in sub-tropical and temperate tidal flats". Journal of the Marine Biological Association of the United Kingdom 89, n. 2 (16 ottobre 2008): 399–404. http://dx.doi.org/10.1017/s0025315408002683.

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Macroalgal and seagrass communities are widely distributed in marine and brackish shallow water and have high productivity. The primary production in marine costal areas is often transported to intertidal flats by waves and currents and beached on the flats. Thus, we hypothesized that the macroalgae and seagrasses are food sources for benthic communities on intertidal flats where some gastropod species often dominate. We performed comparisons of food sources among different gastropod species on sub-tropical and temperate tidal flats (26° and 38°N, respectively), and used isotope mixing models using carbon and nitrogen stable isotopes. A mixing model for stable isotopes, IsoSource, revealed that main food sources for three snails were macroalgae (50–56%) and seagrass (39–45%) at the temperate site. The contributions of terrestrial plants, sediment organic matter and benthic microalgae were weaker than those of macroalgae and seagrasses. At the sub-tropical site, snails fed mainly on macroalgae. The differences in food sources between snail species were not remarkable, although the nitrogen values were slightly different. It would thus appear that macroalgae and seagrass play an important role in the food webs not only in their own habitats but also on the adjacent tidal flats.
7

Gubelit, Yulia I. "Opportunistic Macroalgae as a Component in Assessment of Eutrophication". Diversity 14, n. 12 (14 dicembre 2022): 1112. http://dx.doi.org/10.3390/d14121112.

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For the last few decades, coastal eutrophication with the associated mass development of opportunistic macroalgae has increased on a global scale. Since the end of the 2000’s, the number of studies of macroalgal blooms also increased many times. Mass occurrences of such species as Cladophora spp., Ulva spp., and Spirogyra spp. caused a necessity to improve existing methods of ecological assessment and develop new ones. There are many indices based on macroalgae and developed for marine and estuarine ecosystems. However, for correct evaluation, they demand a presence of a number of species, including perennial species from the order Fucales. This requirement cannot be satisfied in fresh or brackish waters, including some estuaries, because often, the freshwater communities are dominated by only one or two opportunistic species. The present paper defines the most relevant topics in studies of macroalgal blooms and reviews indices and metrics which can be recommended for the ecological assessment in diverse habitats influenced or dominated by opportunistic macroalgae species. For ecological assessment of opportunistic communities, according to their seasonal peculiarities, the author recommends, besides biomass, involving evaluation of algal mats (thickness, coverage) and signs of hypoxia.
8

Kumagai, Naoki H., Jorge García Molinos, Hiroya Yamano, Shintaro Takao, Masahiko Fujii e Yasuhiro Yamanaka. "Ocean currents and herbivory drive macroalgae-to-coral community shift under climate warming". Proceedings of the National Academy of Sciences 115, n. 36 (20 agosto 2018): 8990–95. http://dx.doi.org/10.1073/pnas.1716826115.

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Coral and macroalgal communities are threatened by global stressors. However, recently reported community shifts from temperate macroalgae to tropical corals offer conservation potential for corals at the expense of macroalgae under climate warming. Although such community shifts are expanding geographically, our understanding of the driving processes is still limited. Here, we reconstruct long-term climate-driven range shifts in 45 species of macroalgae, corals, and herbivorous fishes from over 60 years of records (mainly 1950–2015), stretching across 3,000 km of the Japanese archipelago from tropical to subarctic zones. Based on a revised coastal version of climate velocity trajectories, we found that prediction models combining the effects of climate and ocean currents consistently explained observed community shifts significantly better than those relying on climate alone. Corals and herbivorous fishes performed better at exploiting opportunities offered by this interaction. The contrasting range dynamics for these taxa suggest that ocean warming is promoting macroalgal-to-coral shifts both directly by increased competition from the expansion of tropical corals into the contracting temperate macroalgae, and indirectly via deforestation by the expansion of tropical herbivorous fish. Beyond individual species’ effects, our results provide evidence on the important role that the interaction between climate warming and external forces conditioning the dispersal of organisms, such as ocean currents, can have in shaping community-level responses, with concomitant changes to ecosystem structure and functioning. Furthermore, we found that community shifts from macroalgae to corals might accelerate with future climate warming, highlighting the complexity of managing these evolving communities under future climate change.
9

Quezada-Perez, Fabio, Sebastián Mena, Cindy Fernández-García e Juan José Alvarado. "Status of Coral Reef Communities on the Caribbean Coast of Costa Rica: Are We Talking about Corals or Macroalgae Reefs?" Oceans 4, n. 3 (20 settembre 2023): 315–30. http://dx.doi.org/10.3390/oceans4030022.

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In the past decades, one of the most widely reported phenomena on Caribbean reefs is the general fall in coral cover and rise in macroalgae. Reefs with low coral cover and high macroalgal abundances are often presumed to provide poorer ecosystem functions and services. In this study, we assessed the condition of coral reefs on the Caribbean Coast of Costa Rica and determined how eight key ecosystem metrics varied in response to different coral and fleshy macroalgae covers. Most reefs surveyed had high fleshy macroalgae and low live coral covers, with an average (±SD) of 31 ± 28% and 14 ± 13% per site. The value of many of the ecosystem metrics estimated for coral reefs of the region appears to be lower than what has been reported for other areas in the Caribbean. We found that the rugosity, urchin density, fish richness, total fish biomass, large fish density, and the potential fishery value of the reef were higher in sites with low fleshy macroalgae covers (<10%). Our results concur with the prevailing paradigm that an increase in macroalgae abundance could reduce the ecosystem services provided by coral reefs.
10

Necchi-Júnior, O., L. H. Z. Branco e C. C. Z. Branco. "Ecological distribution of stream macroalgal communities from a drainage basin in the Serra da Canastra National Park, Minas Gerais, Southeastern Brazil". Brazilian Journal of Biology 63, n. 4 (novembre 2003): 635–46. http://dx.doi.org/10.1590/s1519-69842003000400010.

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Twelve stream segments were sampled four times in 1998-1999 (one sampling per season) in the drainage basin of the upper São Francisco River (19º45'-21º25'S, 49º05'-51º30'W), situated in Serra da Canastra National Park, at altitudes ranging from 1,175 to 1,400 m. The macroalgae survey resulted in 30 species, with a predominance of Cyanophyta (12 species = 40%) and Chlorophyta (11 species = 36.5%) and a lower proportion of Rhodophyta (seven species = 23.5%). Two species, Klebsormidium rivulare (Chlorophyta) and Kyliniella latvica (Rhodophyta), were new records for Brazil. Capsosira sp. and Stigonema sp. (Cyanophyta) and the "Chantransia" stage of Batrachospermum (Rhodophyta) were the most widespread macroalgae, occurring in six sampling sites, whereas 11 species were found at only one site. The proportion of macroalgal morphological types were as follows: mats (33%), free filaments (27%), gelatinous filaments (27%), crusts (7%), tufts (3%), and gelatinous colonies (3%). The flora revealed few species in common (4%-8%) with stream macroalgae from other Brazilian regions. The macroalgal communities proved to have species richness values close to the highest values reported in previous studies. The patterns typical for stream macroalgal communities (patchy distribution and dominance of few species) were also found in this basin. However, the stream variables most influential in macroalgal distribution in this study (rocky substratum, low pH, high COD, water color, and current velocity) were essentially the same that best describe the limnological characteristics of this lotic ecosystem. In addition, this combination of variables differed sharply from results of previous studies in other Brazilian stream ecosystems.
11

Lõugas, Laura, Tiit Kutser, Jonne Kotta e Ele Vahtmäe. "Detecting Long Time Changes in Benthic Macroalgal Cover Using Landsat Image Archive". Remote Sensing 12, n. 11 (11 giugno 2020): 1901. http://dx.doi.org/10.3390/rs12111901.

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Coastal macroalgae worldwide provide multiple ecological functions and support vital ecosystem services. Thereby, it is important to monitor changes in the extent of benthic macroalgal cover. However, as in situ sampling is costly and time-consuming, areal estimates of macroalgal species cover are often based only on a limited number of samples. This low sampling effort likely yields very biased estimates, as macroalgal communities are often characterized by large spatial variability at multiple spatial scales. Moreover, ecological time series are often short-term, making it impossible to assess changes in algal communities over decades and relate this to different human pressures and/or climate change. The Landsat series satellites have operated for 40 years. In the current study, we tested if the Landsat sensors could be used for mapping the cover of shallow water benthic macroalgae. This study was carried out at two sites in the West Estonian Archipelago, in the northeastern Baltic Sea. Our results show that the Landsat imagery accurately reflected both spatial and temporal variability in benthic algal cover. To conclude, the current methodology can be used to improve the existing assessments of areal macroalgal cover, or to estimate the cover values, in areas and times lacking ecological observations.
12

Amsler, Charles D., Margaret O. Amsler, Michelle D. Curtis, James B. McClintock e Bill J. Baker. "Impacts of gastropods on epiphytic microalgae on the brown macroalga Himantothallus grandifolius". Antarctic Science 31, n. 2 (15 marzo 2019): 89–97. http://dx.doi.org/10.1017/s0954102019000014.

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AbstractChemically defended benthic macroalgae that dominate shallow, hard bottom communities along the western Antarctic Peninsula support very high densities of mesograzers, particularly amphipods but also small gastropods. Previous studies have demonstrated that the macroalgae and amphipods form a mutualistic relationship. The chemically defended macroalgae provide the amphipods with a refuge from predation while the macroalgae benefit from the amphipods greatly reducing surface fouling by smaller algae. One of the three most important macroalgae in terms of overstory cover, Himantothallus grandifolius, forms huge blades that can carpet the benthos. Field observations suggest that gastropods may be higher in relative abundance in proportion to amphipods on H. grandifolius than on other overstory macroalgae. The present study documents the finding that natural abundances of gastropods on H. grandifolius maintained in mesocosms reduce fouling by microscopic algae, primarily diatoms. However, amphipods are probably also important in keeping the macroalga clean of diatoms in nature. In a smaller scale experiment, three gastropod species were differentially effective at reducing diatom coverage on H. grandifolius. The hypothesis that gastropods benefit from associating with H. grandifolius in potentially gaining a refuge from sea-star predation was also tested but not supported by the experimental results.
13

Tsiamis, Konstantinos, Maria Salomidi, Vasilis Gerakaris, Andrew O. M. Mogg, Elizabeth S. Porter, Martin D. J. Sayer e Frithjof C. Küpper. "Macroalgal vegetation on a north European artificial reef (Loch Linnhe, Scotland): biodiversity, community types and role of abiotic factors". Journal of Applied Phycology 32, n. 2 (3 gennaio 2020): 1353–63. http://dx.doi.org/10.1007/s10811-019-01918-2.

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AbstractVery little is known about the marine macroalgae of artificial reefs—especially in the North Atlantic—despite the growing number and extent of man-made structures in the sea, and even though seaweed communities have paramount importance as primary producers, but also as feeding, reproductive and nursery grounds in coastal ecosystems. This paper explores the macroalgal diversity of a large system of artificial reefs in Loch Linnhe, on the west coast of Scotland, in a quantitative and qualitative study based on diving surveys and correlates the observations with the prevalent abiotic factors. The study was conducted in order to test the hypothesis that artificial reefs can enhance seaweed habitats—in particular, for kelps—and that there is a clear correlation with substrate type. While the reef is home to a large range of biota and abundance of early-successional species of turf and bushy macroalgae, totalling 56 taxa and with Delesseria sanguinea as the dominant species, canopy-forming perennial kelp species are conspicuously relatively rare. Macroalgal vegetation is explored in correlation with reef geometry/geography and depth. Statistical analysis shows benthic communities were strongly affected by substrate type, with turf algae and invertebrates dominating the artificial reefs, while bushy algae dominate the natural ones. Common macroinvertebrates associated with the phytobenthic communities are assessed qualitatively.
14

He, Quan, Linqing Liu, Yujie Qin, Qiang Lin, Guangyan Ni, Binbin Chen, Zengling Ma, Dinghui Zou e Gang Li. "Taxonomic and Morpho-Functional Photosynthetic Patterns of 18 Intertidal Macroalgal Species in the Guangdong–Hong Kong–Macao Greater Bay Area, China". Journal of Marine Science and Engineering 11, n. 7 (13 luglio 2023): 1409. http://dx.doi.org/10.3390/jmse11071409.

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Macroalgae provide food for microbial, meio- and macro-faunal communities in coastal ecosystems, thus mediating nutrient dynamics and functions in these ecosystems. Because of this vital role, it is important to clarify physiological information about macroalgae as it reflects their growth potential in the field. In this study, we examined the biomass, pigment content, and photosynthetic O2 evolution rate versus irradiance curves of 18 macroalgal species from the intertidal zone of the Guangdong–Hong Kong–Macao Greater Bay Area, China, and investigated their photosynthetic patterns in relation to phyla characteristics, morphology, and growth locations. The results showed that green algae had the highest maximum photosynthetic O2 evolution rate (Pmax), light utilization efficiency (α), and dark respiration (Rd) among the three macroalgal phyla; the sheet-like macroalgal species had the highest Pmax, α, and Rd among the four morphological categories. The macroalgal species in the upper intertidal zone showed higher Pmax and α and lower saturation irradiance (EK) and compensation irradiance (EC) than those species in the lower intertidal location. The PCA results showed that the biomass of sheet-like macroalgal species was positively correlated with factor PC1 (50.34%), and that of finely branched species was negatively correlated with factor PC2 (25.17%). In addition, our results indicate that the light absorption and utilization capabilities of macroalgae could determine whether they could dominate the intertidal zone and that their photosynthetic characteristics could be used as a potential indicator of their biomass distribution in the Greater Bay Area.
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Kruss, Aleksandra, Jarosław Tęgowski, Agnieszka Tatarek, Józef Wiktor e Philippe Blondel. "Spatial distribution of macroalgae along the shores of Kongsfjorden (West Spitsbergen) using acoustic imaging". Polish Polar Research 38, n. 2 (27 giugno 2017): 205–29. http://dx.doi.org/10.1515/popore-2017-0009.

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Abstract The identification of macroalgal beds is a crucial component for the description of fjord ecosystems. Direct, biological sampling is still the most popular investigation technique but acoustic methods are becoming increasingly recognized as a very efficient tool for the assessment of benthic communities. In 2007 we carried out the first acoustic survey of the littoral areas in Kongsfjorden. A 2.68 km2 area comprised within a 12.40 km2 euphotic zone was mapped along the fjord’s coast using single- and multi-beam echosounders. The singlebeam echosounder (SBES) proved to be a very efficient and reliable tool for macroalgae detection in Arctic conditions. The multibeam echosounder (MBES) was very useful in extending the SBES survey range, even though it’s ability in discriminating benthic communities was limited. The final result of our investigation is a map of the macroalgae distribution around the fjord, showing 39% macroalgae coverage (1.09 km2) of investigated area between isobaths -0.70 m and -30 m. Zonation analysis showed that most of the studied macroalgae areas occur up to 15 m depth (93%). These results were confirmed by biological sampling and observation in key areas. The potential of acoustic imaging of macrophytes, and a proposed methodology for the processing of acoustic data, are presented in this paper along with preliminary studies on the acoustic reflectivity of macroalgae, also highlighting differences among species. These results can be applied to future monitoring of the evolution of kelp beds in different areas of the Arctic, and in the rest of the world.
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Correia, Kelly M., Scott B. Alford, Benjamin A. Belgrad, Kelly M. Darnell, M. Zachary Darnell, Bradley T. Furman, Margaret O. Hall et al. "Drift macroalgal distribution in northern Gulf of Mexico seagrass meadows". PeerJ 10 (23 agosto 2022): e13855. http://dx.doi.org/10.7717/peerj.13855.

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Drift macroalgae, often found in clumps or mats adjacent to or within seagrass beds, can increase the value of seagrass beds as habitat for nekton via added food resources and structural complexity. But, as algal biomass increases, it can also decrease light availability, inhibit faunal movements, smother benthic communities, and contribute to hypoxia, all of which can reduce nekton abundance. We quantified the abundance and distribution of drift macroalgae within seagrass meadows dominated by turtle grass Thalassia testudinum across the northern Gulf of Mexico and compared seagrass characteristics to macroalgal biomass and distribution. Drift macroalgae were most abundant in areas with higher seagrass shoot densities and intermediate canopy heights. We did not find significant relationships between algal biomass and point measures of salinity, temperature, or depth. The macroalgal genera Laurencia and Gracilaria were present across the study region, Agardhiella and Digenia were collected in the western Gulf of Mexico, and Acanthophora was collected in the eastern Gulf of Mexico. Our survey revealed drift algae to be abundant and widespread throughout seagrass meadows in the northern Gulf of Mexico, which likely influences the habitat value of seagrass ecosystems.
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Jung, Seung Wook, e Chang Geun Choi. "Estimation of Marine Macroalgal Biomass Using a Coverage Analysis". Journal of Marine Science and Engineering 10, n. 11 (7 novembre 2022): 1676. http://dx.doi.org/10.3390/jmse10111676.

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This study was conducted to assess the feasibility of biomass estimation by non-destructive sampling, determine whether the results derived from various types of marine macroalgae are reliable, and a newly proposed method. A quantitative survey was conducted on marine macroalgae communities distributed in the subtidal zone in 67 coastal regions in Korea. Regression analyses were conducted on 11,642 fresh weight datasets covering of 135 species of marine macroalgae. The linear function was FW = 17.721C (adj r2 = 0.745, p < 0.001) and the power function was FW = 4.48C1.251 (adj r2 = 0.891, p < 0.001). Our analysis accounted for the fact that there were three vertically distributed layers of a marine macroalgal assemblages with various shapes (i.e., the Ecklonia complex, the Sargassum and Undaria complex, and the understory complex). For the Ecklonia complex, the linear function was FW = 27.360C (adj r2 = 0.886, p < 0.001) and the power function was FW = 9.626C1.223 (adj r2 = 0.909, p < 0.001). For the Sargassum and Undaria complex, the linear function was FW = 18.389C (adj r2 = 0.916, p < 0.001) and the power function was FW = 6.567C1.255 (adj r2 = 0.942, p < 0.001). For the understory complex, the linear function was FW = 10.419C (adj r2 = 0.737, p < 0.001) and the power function was FW = 4.377C1.182 (adj r2 = 0.871, p < 0.001). Our findings demonstrated that the proposed method can accurately estimate the primary productivity of a wide range of coastal ecosystems based on remote sensing and non-destructive surveys of small-scale marine macroalgal communities.
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Wulandari, Sekar Ajeng, Bintang Marhaeni e Maria Dyah Nur Meinita. "Macroalgae Community Structure at Semak Daun Island, Kepulauan Seribu, Indonesia". Omni-Akuatika 16, n. 3 (30 dicembre 2020): 21. http://dx.doi.org/10.20884/1.oa.2020.16.3.847.

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Semak Daun Island was part of the Kepulauan Seribu which was a marine tourism destination such as snorkeling and diving site. The existence of these activities had been affecting the condition of the biota community that lives in these waters including macroalgae. The condition of macroalgae communities can be observed by abundance, diversity, uniformity and dominance analysis that occur in these communities that are known as the community structure. The purpose of this study was to determine the structure of macroalgae communities (abundance, diversity, uniformity and dominance) in Semak Daun Island. This research results was found 3 divisions, 10 orders, 13 families, 15 genera and 20 species of macroalgae. The abundance of macroalgae ranges from 235 - 782 individuals/100m2, classified as low abundance. Diversity ranges from 0.96 to 1.83, classified as low diversity. Uniformity ranges from 0.4 to 0.71, including the moderate uniformity and Dominance ranges from 0.22 to 0.57 belong to the low to moderate category, with the most dominant species being Galaxaura rugosa. Physics-chemical parameters of water in general are included in the normal range to support macroalgae life. Based on this, the condition of the macroalgae community structure on Semak Daun Island which is in a less favorable condition is likely due to the existence of snorkeling and diving activities by tourists. Keywords: community structure, macroalgae, Semak Daun Island
19

Entwisle, TJ. "Macroalgae, in the Upper Yarra and Watts River catchments: Distribution and Phenology". Marine and Freshwater Research 41, n. 4 (1990): 505. http://dx.doi.org/10.1071/mf9900505.

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Studies on the floristics and phenology of macroalgal communities in the upper Yarra and Watts River catchments have shown that the urbanized reaches of the Yarra River near Warburton are relatively species-rich and that they include nearly all macroalgal taxa found in protected catchments upstream. The lower of three river sites near Warburton, however, includes fewer species and is seasonally dominated by Vaucheria bursata, a saproxenous alga. The macroalgal communities on solid rock are distinct from those on loose rock subject to flood movement, and they include more taxa with basally attached filaments. A nearby enriched tributary, McMahons Creek, is dominated by a Spirogyroideae species and is species-poor. Species richness is also low on small-weirs and natural stream habitats in protected upstream catchments. Experimental timber harvesting above a series of small-weirs introduced weed species into the streams, replacing some of the native macroalgal species. Indigenous macroalgal species return 5 or so years after selective timber thinning, but they do not return even 10 years after clear-felling and fertilizing. The macroalgae of the upper Yarra River basin can be grouped into those that can grow throughout the year, those whose growth is restricted by water temperature, and those with a distinct seasonality unrelated to water temperature.
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Al-Khaldi, Wejdan Ahmed, Lafi Al Solami e Sathianeson Satheesh. "Effects of copper and cadmium on physiology and antifouling defense of the marine macroalga Ulva reticulata". Oceanological and Hydrobiological Studies 50, n. 2 (1 giugno 2021): 184–97. http://dx.doi.org/10.2478/oandhs-2021-0017.

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Abstract Heavy metals are major stressors for benthic macroalgal communities in marine ecosystems. In this study, the effects of copper and cadmium on some physiological parameters along with antifouling defense of the marine macroalga Ulva reticulata were assessed under laboratory conditions. Macroalgal samples were treated with three concentrations (1 mg l−1, 3 mg l−1 and 5 mg l−1) of copper and cadmium for 2 and 7 days. After treatment, algal samples were analyzed for chlorophyll-a, carotenoid, total polyphenol and total antioxidant capacity. Also, algal extracts were tested against biofilm-forming bacteria strains to understand differences in antifouling activity. The results indicated that exposure of U. reticulata to copper and cadmium, on the one hand, induced protective mechanisms such as total phenol production and antioxidant capacity against metal stress and, on the other hand, reduced photosynthesis. While the extract obtained from control algal samples showed a strong inhibitory effect on the growth of biofilm-forming bacteria, treatment with heavy metals resulted in reduced antibiofilm activity. In general, the results revealed that exposure of macroalgae to heavy metals can affect antifouling defense traits in addition to changes in photosynthetic pigment content.
21

Cheutin, Marie-Charlotte, Sébastien Villéger, Christina C. Hicks, James P. W. Robinson, Nicholas A. J. Graham, Clémence Marconnet, Claudia Ximena Ortiz Restrepo, Yvan Bettarel, Thierry Bouvier e Jean-Christophe Auguet. "Microbial Shift in the Enteric Bacteriome of Coral Reef Fish Following Climate-Driven Regime Shifts". Microorganisms 9, n. 8 (11 agosto 2021): 1711. http://dx.doi.org/10.3390/microorganisms9081711.

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Replacement of coral by macroalgae in post-disturbance reefs, also called a “coral-macroalgal regime shift”, is increasing in response to climate-driven ocean warming. Such ecosystem change is known to impact planktonic and benthic reef microbial communities but few studies have examined the effect on animal microbiota. In order to understand the consequence of coral-macroalgal shifts on the coral reef fish enteric bacteriome, we used a metabarcoding approach to examine the gut bacteriomes of 99 individual fish representing 36 species collected on reefs of the Inner Seychelles islands that, following bleaching, had either recovered to coral domination, or shifted to macroalgae. While the coral-macroalgal shift did not influence the diversity, richness or variability of fish gut bacteriomes, we observed a significant effect on the composition (R2 = 0.02; p = 0.001), especially in herbivorous fishes (R2 = 0.07; p = 0.001). This change is accompanied by a significant increase in the proportion of fermentative bacteria (Rikenella, Akkermensia, Desulfovibrio, Brachyspira) and associated metabolisms (carbohydrates metabolism, DNA replication, and nitrogen metabolism) in relation to the strong turnover of Scarinae and Siganidae fishes. Predominance of fermentative metabolisms in fish found on macroalgal dominated reefs indicates that regime shifts not only affect the taxonomic composition of fish bacteriomes, but also have the potential to affect ecosystem functioning through microbial functions.
22

Phillips, J. A., C. Conacher e J. Horrocks. "Marine macroalgae from the Gulf of Carpentaria, tropical northern Australia". Australian Systematic Botany 12, n. 3 (1999): 449. http://dx.doi.org/10.1071/sb98010.

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Over the last two decades, CSIRO surveys of the seagrass communities in the south-western Gulf of Carpentaria and at Groote Eylandt, the Northern Territory, have provided opportunities for the collection of marine macroalgae from this poorly explored, remote region. Although the cruises did not concentrate on macroalgal communities which typically grow on rocky substrates, 64 specific and subspecific taxa of marine Chlorophyta, Phaeophyceae and Rhodophyta were collected, including 30 species newly recorded for the Gulf. The majority of Gulf species also occur on the tropical eastern Australian coast. One hundred and thirteen macroalgal taxa are now known to occur in the Gulf of Carpentaria, the number from the present study supplemented by collections from the 1948 Arnhem Land Expedition and from an ethnobiological study on Groote Eylandt during the 1970s. Twelve species are recorded by all three Gulf studies and 23 species are reported by two studies. The relatively low number of species common to more than one study is thought to result from each study's narrow sampling window which fails to adequately document the considerable spatial and temporal variability of macroalgal species. Accordingly, the number of species presently recorded for the Gulf is considered to be an underestimate of macroalgal biodiversity for the region. It is clear that further detailed taxonomic and ecological investigations are urgently required before the full extent of macroalgal biodiversity in tropical Australia can be appreciated.
23

Trias, Rosalia, Arantzazu García-Lledó, Noemí Sánchez, José Luis López-Jurado, Sara Hallin e Lluís Bañeras. "Abundance and Composition of Epiphytic Bacterial and Archaeal Ammonia Oxidizers of Marine Red and Brown Macroalgae". Applied and Environmental Microbiology 78, n. 2 (11 novembre 2011): 318–25. http://dx.doi.org/10.1128/aem.05904-11.

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ABSTRACTAmmonia-oxidizing bacteria (AOB) and archaea (AOA) are important for nitrogen cycling in marine ecosystems. Little is known about the diversity and abundance of these organisms on the surface of marine macroalgae, despite the algae's potential importance to create surfaces and local oxygen-rich environments supporting ammonia oxidation at depths with low dissolved oxygen levels. We determined the abundance and composition of the epiphytic bacterial and archaeal ammonia-oxidizing communities on three species of macroalgae,Osmundaria volubilis,Phyllophora crispa, andLaminaria rodriguezii, from the Balearic Islands (western Mediterranean Sea). Quantitative PCR of bacterial and archaeal 16S rRNA andamoAgenes was performed. In contrast to what has been shown for most other marine environments, the macroalgae's surfaces were dominated by bacterialamoAgenes rather than those from the archaeal counterpart. On the basis of the sequences retrieved from AOB and AOAamoAgene clone libraries from each algal species, the bacterial ammonia-oxidizing communities were related toNitrosospiraspp. and toNitrosomonas europaeaand only 6 out of 15 operational taxonomic units (OTUs) were specific for the host species. Conversely, the AOA diversity was higher (43 OTUs) and algal species specific, with 17 OTUs specific forL. rodriguezii, 3 forO. volubilis, and 9 forP. crispa. Altogether, the results suggest that marine macroalgae may exert an ecological niche for AOB in marine environments, potentially through specific microbe-host interactions.
24

Ba-Akdah, M. A., S. Satheesh e A. A. Al-Sofyani. "Habitat preference and seasonal variability of epifaunal assemblages associated with macroalgal beds on the Central Red Sea coast, Saudi Arabia". Journal of the Marine Biological Association of the United Kingdom 96, n. 7 (15 ottobre 2015): 1457–67. http://dx.doi.org/10.1017/s0025315415001678.

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Macroalgal communities of coastal ecosystems play a key role in maintaining overall coastal biodiversity. In this study, habitat preference (macroalgal host preference) and temporal changes (season) of epifaunal communities associated to five macroalgal species such as Padina, Sargassum, Ulva, Acanthophora and Gracilaria were observed at seasonal intervals (summer and winter) for 2 years from May 2012 to March 2014 on the Jeddah coastal waters of the Red Sea. Major epifaunal groups observed included polychaetes, amphipods, isopods, gastropods, mussels and crabs. Polychaetes were represented by 10 species followed by amphipods with five species. The abundance of gastropods, polychaetes and mussels showed significant variation between the macroalgae irrespective of morphology. Generally, the abundance of these taxa were high on Padina and low on Sargassum. Significant seasonal changes were observed on the abundance of polychaetes, amphipods and isopods. The abundance of some epifaunal groups showed a significant relationship with environmental parameters such as surface water temperature, salinity, pH and dissolved oxygen content.
25

Smith, Jennifer E., Rusty Brainard, Amanda Carter, Saray Grillo, Clinton Edwards, Jill Harris, Levi Lewis et al. "Re-evaluating the health of coral reef communities: baselines and evidence for human impacts across the central Pacific". Proceedings of the Royal Society B: Biological Sciences 283, n. 1822 (13 gennaio 2016): 20151985. http://dx.doi.org/10.1098/rspb.2015.1985.

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Numerous studies have documented declines in the abundance of reef-building corals over the last several decades and in some but not all cases, phase shifts to dominance by macroalgae have occurred. These assessments, however, often ignore the remainder of the benthos and thus provide limited information on the present-day structure and function of coral reef communities. Here, using an unprecedentedly large dataset collected within the last 10 years across 56 islands spanning five archipelagos in the central Pacific, we examine how benthic reef communities differ in the presence and absence of human populations. Using islands as replicates, we examine whether benthic community structure is associated with human habitation within and among archipelagos and across latitude. While there was no evidence for coral to macroalgal phase shifts across our dataset we did find that the majority of reefs on inhabited islands were dominated by fleshy non-reef-building organisms (turf algae, fleshy macroalgae and non-calcifying invertebrates). By contrast, benthic communities from uninhabited islands were more variable but in general supported more calcifiers and active reef builders (stony corals and crustose coralline algae). Our results suggest that cumulative human impacts across the central Pacific may be causing a reduction in the abundance of reef builders resulting in island scale phase shifts to dominance by fleshy organisms.
26

Majewska, Roksana, Maria Cristina Gambi, Cecilia Maria Totti e Mario De Stefano. "Epiphytic diatom communities of Terra Nova Bay, Ross Sea, Antarctica: structural analysis and relations to algal host". Antarctic Science 25, n. 4 (10 gennaio 2013): 501–13. http://dx.doi.org/10.1017/s0954102012001101.

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AbstractEpiphytic diatoms are important constituents of the Southern Ocean coastal water ecosystem, being a key element in many of the Antarctic trophic chains. However, only limited information exists relating to these microalgal communities. Here we describe our findings of a study on epiphytic diatoms from Terra Nova Bay (Ross Sea, Antarctica) based on material collected during the summer campaigns spanning from 1990–2004. Observations of diatoms associated with three rhodophyte species (Iridaea cordata (Turner) Bory, Phyllophora antarctica Gepp & Gepp, and Plocamium cartilagineum (L.) Dixon) were carried out with the use of a scanning electron microscope. A total of 73 diatom taxa (32 genera) were distinguished, of which 20 taxa exceeded 3% of total abundance. Cocconeis fasciolata (Ehrenberg) Brown, Navicula perminuta Grunow, and Fragilariopsis nana (Steemann Nielsen) Paasche appeared in every sample. The analysis of similarities (ANOSIM) test as well as non-metric multidimensional scaling analysis indicated the nature of host organism as a major factor influencing associated diatom community structure, whereas depth, site, and time of sampling seemed to be less important. The epizooic communities associated with sessile fauna epiphytic on macroalgae differed significantly from those associated with macroalgal surface. A pronounced difference between the communities epiphytic on various host macroalgae species was also observed, although most of the dissimilarities occurred between diatom taxa of the same growth form.
27

González, Jorge E., Beatriz Yannicelli, Fabián Rodríguez-Zaragoza e Marco Ortiz. "Biogenic habitats as drivers of invertebrate benthic community variability in Tongoy Bay (SE Pacific coast): implications of macroalga harvesting". Scientia Marina 87, n. 1 (30 marzo 2023): e057. http://dx.doi.org/10.3989/scimar.05350.057.

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Habitat biogenic complexity is thought to exert a significant positive influence on benthic communities. We examined the link between the seasonal variability of macroinvertebrate community structure (species and trophic richness, diversity and biomass) and habitats with different macroalgal assemblages. We identified macroinvertebrates and algae from 336 samples spread over four types of habitat: sand, mud, sand-gravel and seagrass meadows. Considering the whole macroalgal and macroinvertebrate assemblage, we confirmed that macroinvertebrate community variability within and among habitats can be mainly (but not only) explained by a few macroalgal structuring species. The variability of macroinvertebrate communities between habitats and seasons depended on the changes in the relative contribution of the explanatory biostructuring species in the overall algal community. Biomass, trophic behaviour and species richness remained stable in habitats with conspicuous macroalgal communities in contrast with habitats devoid of macroalgae. However, invertebrate species richness and biomass remained stable only in habitats whose dominant species did not change between seasons and not in those where dominant structuring species shifted. The seasonal change in a key structuring macroalgal species (Condracanthus chamissoi), probably as a result of harvesting, led to a major reduction in invertebrate community biomass and richness both in the particular habitat and in those nearby at species level. These consequences are especially important for invertebrates linked by trophic relationships and targeted by fisheries.
28

Tompkins, Paul, e Matthias Wolff. "Galápagos macroalgae: A review of the state of ecological knowledge". Revista de Biología Tropical 65, n. 1 (23 settembre 2016): 375. http://dx.doi.org/10.15517/rbt.v65i1.18139.

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Previous work has highlighted the critical role of macroalgal productivity and dynamics in supporting and structuring marine food webs. Spatio-temporal variability in macroalgae can alter coastal ecosystems, a relationship particularly visible along upwelling-influenced coastlines. As a result of its equatorial location and nutrient rich, upwelling-influenced waters, the Galápagos Archipelago in the East Pacific, hosts a productive and biodiverse marine ecosystem. Reports and collections of macroalgae date back to the Beagle voyage, and since then, more than three hundred species have been reported. However, their ecology and functional role in the ecosystem is not well understood. According to various disparate and in part anecdotal sources of information, abundant and diverse communities exist in the Western regions of the archipelago, the North is essentially barren, and in the central/South abundance and distribution is variable and less well defined. Both oceanographic conditions and herbivore influence have been theorized to cause this pattern. Extensive changes in macroalgal productivity and community composition have occurred during strong ENSO events, and subsequent declines in marine iguana (an endemic and iconic grazer) populations have been linked to these changes. Iguanas are only one species of a diverse and abundant group of marine grazers in the system, highlighting the potentially important role of macroalgal productivity in the marine food web. This review represents a first compilation and discussion of the available literature and presents topics for future research.
29

Rishworth, Gavin M., Renzo Perissinotto, Matthew S. Bird e Noémie Pelletier. "Grazer responses to variable macroalgal resource conditions facilitate habitat structuring". Royal Society Open Science 5, n. 1 (gennaio 2018): 171428. http://dx.doi.org/10.1098/rsos.171428.

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Consumer responses to altered resource conditions can vary depending on dietary preference, resource characteristics and secondary resource features such as shelter. These can have cascading effects, especially if the consumed resource impacts on overall ecological functioning. In this study, we assessed the dietary composition of grazer communities following seasonal changes in the characteristics of their staple food-source (macroalgae). This was conducted in the living stromatolite pools growing along the coast of South Africa. Stable isotope mixing models suggested that following macroalgal bleaching in summer, metazoan consumers shifted their diet from predominantly macroalgae to a generalist composition. This has important implications for the integrity of the stromatolite matrix and its layered deposition. Where previously in winter stromatolite microalgae comprised a minor component of metazoan consumer diets, in summer, following a change in the resource conditions of macroalgae, microalgae featured more prominently in grazer diets. This seasonal grazing pressure on stromatolite-related resources probably promotes the pattern of annual layering observed in the stromatolite accretion. It also demonstrates a mechanism whereby grazer dietary shifts following a change in their preferred food resource can affect the ecosystem structure of their environment, specifically the stromatolite layering process which responds to microalgal growth or grazing conditions.
30

Rugebregt, Marsya Jaqualine, Hairati Arfah e Ferdinand Pattipeilohy. "Correlation between macroalgae diversity and water quality in Southwest Maluku waters". Marine Research in Indonesia 45, n. 1 (27 luglio 2020): 25–32. http://dx.doi.org/10.14203/mri.v45i1.573.

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Macroalgae play an important role in the ecosystem of the coastal area, serving as a shelter ground, nursery ground, and feeding ground. Macroalgae communities are directly influenced by water quality. This study aim was to determine the correlation between the macroalgae diversity and water quality in southwest Maluku waters. This research was conducted in September 2019 at seven research stations. Macroalgae samples were collected by transect method, while seawater quality was measured using Van Dorn Water Sampler. The macroalgae diversity, species composition, and dominance were determined. Water quality parameters analyzed were temperature, salinity, pH, phosphate, nitrate, and ammonia. Correlations between macroalgae diversity and water quality were determined using principal component analysis. This study recorded 45 species of macroalgae consisting of 15 species of red algae (Rhodophyta), 6 species of brown algae (Phaeophyta), and 24 species of green algae (Chlorophyta). Diversity Index varied ranged from low to moderate categories (0.969 - 2.345). Water quality in general is still quite good for macroalgae life. Macroalgae diversity and water quality correlate and influence each other.
31

Binning, Sandra, Charalampos Mavromatis e Frédéric Guichard. "Density-dependent succession in Caribbean seagrass communities". McGill Science Undergraduate Research Journal 2, n. 1 (31 marzo 2007): 28–31. http://dx.doi.org/10.26443/msurj.v2i1.138.

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It is important to understand the patterns of succession and competition in seagrass beds as a way of explaining recovery processes after disturbances. This project studies macroalgae-seagrass succession dynamics in the Caribbean, and tests the importance of interspecific density-dependence (competition) in predicting the successional sequence of species in a wave-disturbed ecosystem. Competition and gap disturbances seem to be the dominant factors influencing species coexistence in offshore regions whereas habitat partitioning driven by differences in depth, disturbance and wave action creates distinct zones of macroalgae and seagrass inshore. In general, density dependent processes across our study site were influenced by major physical gradients. This study has important consequences for predicting dramatic shifts in large-scale seagrass ecosystems, which act as ecological engineers and provide many ecosystem services.
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M. Kuba, Gabrielle, Heather L. Spalding, Kristina M. Hill-Spanik, Taylor M. Williams, Monica O. Paiano, Alison R. Sherwood, Brian B. Hauk, Randall K. Kosaki e Heather Fullerton. "Characterization of macroalgal-associated microbial communities from shallow to mesophotic depths at Manawai, Papahānaumokuākea Marine National Monument, Hawai‘i". PeerJ 11 (3 ottobre 2023): e16114. http://dx.doi.org/10.7717/peerj.16114.

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The Papahānaumokuākea Marine National Monument, Hawai‘i, is one of the most isolated and protected archipelagos in the world, making it a natural laboratory to examine macroalgal-microbial diversity because of limited direct anthropogenic impacts. We collected the most abundant macroalgae from nine sites ranging from shallow subtidal (1.5 m) to mesophotic (75 m) depths around Manawai (Pearl and Hermes Atoll). We characterized the macroalgal bacterial communities via high-throughput amplicon sequencing and compared the influence of host phylum, species, site, and depth on these relationships at a single atoll. Ochrophyta species had the lowest bacterial diversity compared to Chlorophyta and Rhodophyta. Site and/or depth may influence the microbial community structure associated with Microdictyon setchellianum, indicating a possible disconnect of these microbial communities among habitats. Chondria tumulosa, a cryptogenic species with invasive traits, differed in associated microbiota compared to the native Laurencia galtsoffii, an alga from the same family collected at the same site and depth. While there was overlap of bacterial communities across sites for some algal species, the majority had minimal macroalgal-microbial community connectivity across Manawai. This mesophotic system, therefore, did not appear to be refugia for shallow water coral reefs at microscopic scales. Additional studies are required to identify other significant influences on microbial community variation.
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Farrugia Drakard, Veronica, Sandro Lanfranco e Patrick J. Schembri. "Macroalgal fouling communities as indicators of environmental change: potential applications for water quality monitoring". Journal of the Marine Biological Association of the United Kingdom 98, n. 7 (3 luglio 2017): 1581–88. http://dx.doi.org/10.1017/s0025315417001102.

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Macroalgal fouling communities are potentially useful as bioindicators in environmental monitoring as they are considered to be sensitive to changes in environmental conditions and the use of artificial substrata facilitates the implementation of standardized sampling strategies. The response of macroalgal fouling communities on buoys to changes in water quality was investigated with a view to the possible utilization of these assemblages in environmental monitoring programmes. Seven study sites were selected based on previously collected environmental data and Principal Components Analysis (PCA) was used to order sites according to beam attenuation coefficient (BAC) and concentration of dissolved nitrates and phosphates, relative to a minimally impacted reference site. At each site, all fouling macroalgae were collected from 10 buoys of standard shape and size, and were identified to the lowest possible taxonomic level. Species composition and species dominance were highly variable among impacted sites, indicating that qualitative aspects of community structure may not be useful as indicators of changes in water quality. However, higher levels of nutrient enrichment and turbidity were associated with lower macroalgal species richness, lower overall abundances, and decreased diversities, and therefore these quantitative aspects of community structure are potentially useful as indicators of environmental change. Intermediate levels of turbidity and nutrient enrichment were associated with lower evenness, but did not influence species richness, suggesting that macroalgal abundances respond to changes in environmental conditions before species replacement occurs.
34

Diruit, Wendy, Anthony Le Bris, Touria Bajjouk, Sophie Richier, Mathieu Helias, Thomas Burel, Marc Lennon, Alexandre Guyot e Erwan Ar Gall. "Seaweed Habitats on the Shore: Characterization through Hyperspectral UAV Imagery and Field Sampling". Remote Sensing 14, n. 13 (29 giugno 2022): 3124. http://dx.doi.org/10.3390/rs14133124.

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Intertidal macroalgal habitats are major components of temperate coastal ecosystems. Their distribution was studied using field sampling and hyperspectral remote mapping on a rocky shore of Porspoder (western Brittany, France). Covers of both dominating macroalgae and the sessile fauna were characterized in situ at low tide in 24 sampling spots, according to four bathymetric levels. A zone of ca. 17,000 m2 was characterized using a drone equipped with a hyperspectral camera. Macroalgae were identified by image processing using two classification methods to assess the representativeness of spectral classes. Finally, a comparison of the remote imaging data to the field sampling data was conducted. Seven seaweed classes were distinguished by hyperspectral pictures, including five different species of Fucales. The maximum likelihood (MLC) and spectral angle mapper (SAM) were both trained using image-derived spectra. MLC was more accurate to classify the main dominating species (Overall Accuracy (OA) 95.1%) than SAM (OA 87.9%) at a site scale. However, at sampling points scale, the results depend on the bathymetric level. This study evidenced the efficiency and accuracy of hyperspectral remote sensing to evaluate the distribution of dominating intertidal seaweed species and the potential for a combined field/remote approach to assess the ecological state of macroalgal communities.
35

Spiers, Lindsay, e Thomas K. Frazer. "Comparison of feeding preferences of herbivorous fishes and the sea urchin Diadema antillarum in Little Cayman". PeerJ 11 (15 novembre 2023): e16264. http://dx.doi.org/10.7717/peerj.16264.

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On Caribbean coral reefs, losses of two key groups of grazers, herbivorous fishes and Diadema antillarum, coincided with dramatic increases in macroalgae, which have contributed to decreases in the resilience of these coral reefs and continued low coral cover. In some locations, herbivorous reef fishes and D. antillarum populations have begun to recover, and reductions in macroalgal cover and abundance have followed. Harder to determine, and perhaps more important, are the combined grazing effects of herbivorous fishes and D. antillarum on the structure of macroalgal communities. Surprisingly few studies have examined the feeding preferences of D. antillarum for different macroalgal species, and there have been even fewer comparative studies between these different herbivore types. Accordingly, a series of in-situ and ex-situ feeding assays involving herbivorous fishes and D. antillarum were used to examine feeding preferences. Ten macrophytes representing palatable and chemically and/or structurally defended species were used in these assays, including nine macroalgae, and one seagrass. All species were eaten by at least one of the herbivores tested, although consumption varied greatly. All herbivores consumed significant portions of two red algae species while avoiding Halimeda tuna, which has both chemical and structural defenses. Herbivorous fishes mostly avoided chemically defended species while D. antillarum consumed less of the structurally defended algae. These results suggest complementarity and redundancy in feeding by these different types of herbivores indicating the most effective macroalgal control and subsequent restoration of degraded coral reefs may depend on the recovery of both herbivorous fishes and D. antillarum.
36

Koutsoukos, Victor de Souza, Roberto Campos Villaça e Maria Teresa Menezes de Széchy. "THE STRUCTURE OF SUBTIDAL MACROALGAL ASSEMBLAGES AT THE TAMOIOS ECOLOGICAL STATION, A THREATENED CONSERVATION UNIT IN RIO DE JANEIRO, BRAZIL". Brazilian Journal of Oceanography 63, n. 1 (marzo 2015): 71–82. http://dx.doi.org/10.1590/s1679-87592015082606301.

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The structure of subtidal rocky bottom communities at Tamoios Ecological Station (TES), situated in Ilha Grande Bay, Rio de Janeiro State, as well as in other Brazilian marine protected areas, is insufficiently characterized. The present study describes the macroalgal assemblages of shallow subtidal rocky bottoms on two islands of the TES-Imboassica (IM) and Búzios Pequena (BP)adopting species and genera as observational units. Two sites were surveyed on each island in summer 2011. Random 30x30 cm quadrats (n=3) were scraped to collect all macroalgae except crustose species. The subtidal assemblages, in which 58 macroalgal species occurred, were characterized by the high frequency and percent cover of Sargassum vulgare C. Agardh (56.8±8.4%). The sites differed significantly in total number of species and Shannon-Weiner diversity index (PERMANOVA, p<0.05). According to SIMPER, the macroalgal genera that most contributed to the dissimilarities of cover between the sites (contribution >5%) were Sargassum, Laurencia, Wrangelia, Canistrocarpus, Asparagopsis, Hypnea, Ceratodictyon, Gayliella, Spyridia and Chondria.Dissimilarities within and between the islands, as shown by nMDS of the cover data, suggest that different spatial scales should be considered in monitoring the rocky bottom communities of Ilha Grande Bay.
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Binzer, T., e AL Middelboe. "From thallus to communities: scale effects and photosynthetic performance in macroalgae communities". Marine Ecology Progress Series 287 (2005): 65–75. http://dx.doi.org/10.3354/meps287065.

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38

Dwimayasanti, Rany, e Dedy Kurnianto. "Komunitas Makroalga di Perairan Tayando-Tam, Maluku Tenggara". Oseanologi dan Limnologi di Indonesia 3, n. 1 (30 aprile 2018): 39. http://dx.doi.org/10.14203/oldi.2018.v3i1.82.

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<strong>Community of Macroalgae in Tayando-Tam Waters, Southeast Maluku.</strong> Macroalgae is one of the most important economically valuable resources to be developed for food and medicine. This study aims to determine the structure of macroalgae communities by examining the diversity, density, dominance and environmental conditions of its waters. The research was conducted in Tayando-Tam waters, Southeast Moluccas at five stations in September 2015. The study was conducted by transect along 200 meters from the coast to the open shore, observation stations in 50x50 cm quadrant size. The macroalgae community in Tayando-Tam waters is generally in good condition although there is one station that has a moderate dominance value due to a current limiting factor. The macroalgae obtained in five stations are 37 species, dominated by Acanthophora muscoides species, Hypnea spinella, and Halimeda opuntia. Water conditions are still in the optimal range for macroalgae growth.
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Caronni, Sarah, Chiara Calabretti, Sandra Citterio, Maria Anna Delaria, Rodolfo Gentili, Giovanni Macri, Chiara Montagnani et al. "The interactive effect of herbivory, nutrient enrichment and mucilage on shallow rocky macroalgal communities". PeerJ 7 (13 maggio 2019): e6908. http://dx.doi.org/10.7717/peerj.6908.

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This paper focuses on the interactive short and long-term effect of three different stressors on a macroalgal assemblage. Three stressors are considered: herbivory, nutrients and mucilage. The experiment was conducted in Tavolara Punta Coda Cavallo Marine Protected Area (Mediterranean Sea) during a bloom of the benthic mucilage-producing microalga Chrysophaeum taylorii (Pelagophyceae); this microalga is recently spreading in the Mediterranean Sea. On a rocky substratum, 36 plots 20 × 20 cm in size were prepared. Factorial combinations of three experimental treatments were applied in triplicate, including three grazing levels crossed with two nutrient enrichment and two mucilage removal treatments. Significant differences were observed among treatments 8 weeks later, at the end of summer. In particular, dark filamentous algae were more abundant in all enriched plots, especially where mucilage and macroalgae had been removed; a higher percent cover of crustose coralline algae was instead observed where nutrients had been increased and no grazing pressure acted. Furthermore, the abundance of Dictyota spp. and Laurencia spp. was significantly higher in enriched mucilage-free plots where the grazing pressure was null or low. However, the effects of the treatments on the overall assemblage of the macroalgal community were not long persistent (36 weeks later). These results illustrate the capacity of a shallow-water macroalgal community to quickly recover from the simultaneous impacts of herbivory, nutrient enrichment, and mucilage.
40

Nikolaou, Athanasios, Konstantinos Tsirintanis, Gil Rilov e Stelios Katsanevakis. "Invasive Fish and Sea Urchins Drive the Status of Canopy Forming Macroalgae in the Eastern Mediterranean". Biology 12, n. 6 (24 maggio 2023): 763. http://dx.doi.org/10.3390/biology12060763.

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Canopy-forming macroalgae, such as Cystoseira sensu lato, increase the three-dimensional complexity and spatial heterogeneity of rocky reefs, enhancing biodiversity and productivity in coastal areas. Extensive loss of canopy algae has been recorded in recent decades throughout the Mediterranean Sea due to various anthropogenic pressures. In this study, we assessed the biomass of fish assemblages, sea urchin density, and the vertical distribution of macroalgal communities in the Aegean and Levantine Seas. The herbivore fish biomass was significantly higher in the South Aegean and Levantine compared to the North Aegean. Very low sea urchin densities suggest local collapses in the South Aegean and the Levantine. In most sites in the South Aegean and the Levantine, the ecological status of macroalgal communities was low or very low at depths deeper than 2 m, with limited or no canopy algae. In many sites, canopy algae were restricted to a very narrow, shallow zone, where grazing pressure may be limited due to harsh hydrodynamic conditions. Using Generalized Linear Mixed Models, we demonstrated that the presence of canopy algae is negatively correlated with the biomass of the invasive Siganus spp. and sea urchins. The loss of Cystoseira s.l. forests is alarming, and urgent conservation actions are needed.
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Nadiarti, Nadiarti, Yayu A. La Nafie, Dody Priosambodo, Moh Tauhid Umar, Sri Wahyuni Rahim, Dwi Fajryati Inaku, Nurul Huda Musfirah, Desti Age Paberu e Abigail Mary Moore. "Restored seagrass beds support Macroalgae and Sea Urchin communities". IOP Conference Series: Earth and Environmental Science 860, n. 1 (1 ottobre 2021): 012014. http://dx.doi.org/10.1088/1755-1315/860/1/012014.

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Reverter, Miriam, Matthew Jackson, Nauras Daraghmeh, Christian von Mach e Nina Milton. "11-yr of coral community dynamics in reefs around Dahab (Gulf of Aqaba, Red Sea): the collapse of urchins and rise of macroalgae and cyanobacterial mats". Coral Reefs 39, n. 6 (29 luglio 2020): 1605–18. http://dx.doi.org/10.1007/s00338-020-01988-6.

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AbstractCorals from the Gulf of Aqaba (northern Red Sea) are resilient to high temperatures and therefore this region is regarded as globally important for reef conservation. However, long-term dynamics of coral reef assemblages from the Gulf of Aqaba remain largely understudied. In this study, we analysed the change in benthic, fish and invertebrate assemblages of reefs around Dahab (South Sinai, Egypt) between 2009 and 2019. We also studied the individual trajectories of coral reef benthic categories, key invertebrate and fish species and their relationship. As site emerged as the main factor explaining the variability in coral reef communities, we identified three clusters of sites with similar assemblages. Both benthic, fish and invertebrate assemblages changed considerably at the three site clusters between 2009 and 2019. We found significant increases in fleshy macroalgae (~ 6 to 15%) and cyanobacterial mats (~ 6 to 12%) in all site clusters. Although not observing a significant reduction of hard coral cover, both macroalgae mat cover and cyanobacterial mat cover were significantly negatively related to hard coral cover and hard coral disease. Soft coral cover (mainly corals from the Xeniidae family) decreased significantly in two of the site clusters, their cover being negatively related to macroalgal and cyanobacterial cover. Significant declines in grazer urchins were observed at all site clusters, and a strong negative relationship was found with macroalgae and cyanobacterial mats cover, suggesting urchin decline as one of the main drivers behind algal increases. Different site clusters had different fish trajectories (butterflyfish, parrotfish, surgeonfish and predators), with only damselfish densities significantly decreasing at all sites. A significant decrease in damselfish densities was related to increases in cyanobacterial mats. These findings suggest that if macroalgae and cyanobacteria continue to increase, Dahab coral reefs could undergo degradation, and therefore, more studies are needed to elucidate the drivers behind these algal increases.
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Żelazna-Wieczorek, Joanna, e Monika Mamińska. "Algoflora and vascular flora of a limestone spring in the Warta river valley". Acta Societatis Botanicorum Poloniae 75, n. 2 (2011): 131–43. http://dx.doi.org/10.5586/asbp.2006.016.

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Qualitative analysis of algae, including microhabitats and vascular vegetation in a spring niche, together with basic physical and chemical characteristics is presented. 175 diatom taxa as well as taxa of macroalgae and vascular plants were determined in the spring niche, and the community types were defined. Seasonal variability of diatom communities was observed. The influence of a flood as a catastrophe on the community of diatoms and macroalgae was noticed.
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Burfeid-Castellanos, Andrea M., Rafael P. Martín-Martín, Michael Kloster, Carlos Angulo-Preckler, Conxita Avila e Bánk Beszteri. "Epiphytic diatom community structure and richness is determined by macroalgal host and location in the South Shetland Islands (Antarctica)". PLOS ONE 16, n. 4 (30 aprile 2021): e0250629. http://dx.doi.org/10.1371/journal.pone.0250629.

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The marine waters around the South Shetland Islands are paramount in the primary production of this Antarctic ecosystem. With the increasing effects of climate change and the annual retreat of the ice shelf, the importance of macroalgae and their diatom epiphytes in primary production also increases. The relationships and interactions between these organisms have scarcely been studied in Antarctica, and even less in the volcanic ecosystem of Deception Island, which can be seen as a natural proxy of climate change in Antarctica because of its vulcanism, and the open marine system of Livingston Island. In this study we investigated the composition of the diatom communities in the context of their macroalgal hosts and different environmental factors. We used a non-acidic method for diatom digestion, followed by slidescanning and diatom identification by manual annotation through a web-browser-based image annotation platform. Epiphytic diatom species richness was higher on Deception Island as a whole, whereas individual macroalgal specimens harboured richer diatom assemblages on Livingston Island. We hypothesize this a possible result of a higher diversity of ecological niches in the unique volcanic environment of Deception Island. Overall, our study revealed higher species richness and diversity than previous studies of macroalgae-inhabiting diatoms in Antarctica, which could however be the result of the different preparation methodologies used in the different studies, rather than an indication of a higher species richness on Deception Island and Livingston Island than other Antarctic localities.
45

Fraser, KM, RD Stuart-Smith, SD Ling, FJ Heather e GJ Edgar. "Taxonomic composition of mobile epifaunal invertebrate assemblages on diverse benthic microhabitats from temperate to tropical reefs". Marine Ecology Progress Series 640 (23 aprile 2020): 31–43. http://dx.doi.org/10.3354/meps13295.

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Anthropogenic drivers are flattening reef structure from 3-dimensional habitats composed of macroalgae and live branching corals towards low-profile turfing algae. Our current understanding of the consequences of widespread reef degradation currently fails to consider the responses of small mobile invertebrates (‘epifauna’) to patterns of change amongst reef structural elements (‘microhabitats’). Here, the taxonomic composition of 152 epifaunal assemblages was compared among 21 structurally diverse benthic microhabitats across an Australian temperate to tropical climatic gradient, spanning 28.6 degrees in latitude from Tasmania to the northern Great Barrier Reef. Epifauna varied consistently with different microhabitat types, and to a much lesser extent with latitude. Macroalgae, live branching coral and turfing algae represented 3 extremes for epifaunal community structure, with most microhabitats possessing epifaunal assemblages intermediate between these endpoints. Amongst structural characteristics, epifauna related primarily to the degree of branching and hardness of microhabitats. Mobile invertebrate communities are likely to transform in predictable ways with the collapse of large erect macroalgae and live coral towards low-lying turf-associated communities.
46

Gallucci, Fabiane, Ronaldo A. Christofoletti, Gustavo Fonseca e Gustavo M. Dias. "The Effects of Habitat Heterogeneity at Distinct Spatial Scales on Hard-Bottom-Associated Communities". Diversity 12, n. 1 (20 gennaio 2020): 39. http://dx.doi.org/10.3390/d12010039.

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For marine benthic communities, environmental heterogeneity at small spatial scales are mostly due to biologically produced habitat heterogeneity and biotic interactions, while at larger spatial scales environmental factors may prevails over biotic features. In this study, we investigated how community structure and β-diversity of hard-bottom-associated meio- and macrofauna varied in relation to small-scale (cm–m) changes in biological substrate (an algae “turf” dominated by the macroalgae Gelidium sp., the macroalgae Caulerpa racemosa and the sponge Hymeniacidon heliophile) in a rocky shore and in relation to larger-scale (10’s m) changes in environmental conditions of the same biological substrate (the macroalgae Bostrychia sp) in different habitats (rocky shore vs. mangrove roots). Results showed that both substrate identity and the surrounding environment were important in structuring the smaller-sized meiofauna, particularly the nematode assemblages, whereas the larger and more motile macrofauna was influenced only by larger-scale changes in the surrounding ecosystem. This implies that the macrofauna explores the environment in a larger spatial scale compared to the meiofauna, suggesting that effects of spatial heterogeneity on communities are dependent on organism size and mobility. Changes in taxa composition between environments and substrates highlight the importance of habitat diversity at different scales for maintaining the diversity of the associated fauna.
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Jones, Nicholas P., Joana Figueiredo e David S. Gilliam. "Thermal stress-related spatiotemporal variations in high-latitude coral reef benthic communities". Coral Reefs 39, n. 6 (25 agosto 2020): 1661–73. http://dx.doi.org/10.1007/s00338-020-01994-8.

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AbstractHigh-latitude coral reef communities have been postulated as the first areas to undergo reorganisation under climate change. Tropicalisation has been identified in some high-latitude communities and is predicted in others, but it is unclear how the resident benthic taxa are affected. We conducted a long-term (2007–2016) assessment of changes to benthic community cover in relation to thermal stress duration on the Southeast Florida Reef Tract (SEFRT). Thermal stress events, both hot and cold, had acute (thermal stress duration affected benthic cover that year) and chronic (thermal stress duration affected benthic cover the following year) impacts on benthic cover. Chronic heat stress was associated with declines in cover of the reef-building coral families Acroporidae, Montastraeidae, Meandrinidae, Mussidae and Siderastreidae, which coupled with the absence of cold stress and rising annual temperatures boosted macroalgae cover. Cover of smaller, weedy coral families, Poritidae, Agariciidae and Astrocoeniidae, was either unaffected or positively related to heat stress duration and rising mean temperature. Thermal stress was related to spatiotemporal variations in benthic cover on the SEFRT, likely enhanced by local stressors, such as elevated nutrients and sedimentation. Coral and octocoral cover declined within four of six sub-regions, sponge cover increased in half of the sub-regions, and macroalgae cover increased in four sub-regions during the study. Under current conditions, increased macroalgae and weedy coral cover are anticipated to inhibit reef recovery.
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Setia, T. M., H. S. Fadhillah, P. Wulandari, S. Handayani, S. Sainal, R. A. Praptiwi e J. Sugardjito. "Biodiversity, community structure and potential uses of seaweeds and seagrass in transition zone of Taka Bonerate Kepulauan Selayar biosphere reserve, Indonesia". IOP Conference Series: Earth and Environmental Science 1255, n. 1 (1 ottobre 2023): 012028. http://dx.doi.org/10.1088/1755-1315/1255/1/012028.

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Abstract Macroalgae and seagrass play an important role in marine ecosystems. These organisms have important ecological roles that include primary producers, food sources for other biota, shelters and carbon sinks. Economically, many macroalgae and seagrass species can be exploited as commodities due to their nutritional values and benefits. In Indonesia, macroalgae is traditionally used as food and medicines, especially by communities living in coastal areas. This study aims to unravel the diversity and potential uses of seagrass and macroalgae in Polassi and Tambolongan islands, which is part of the transition zone of the Taka Bonerate Kepulauan Selayar Biosphere Reserve. Identification was performed to analyse several parameters, such as: frequency, density, closure, IVI, dominance and diversity index. Based on the identification results, 7 species of seagrass and 17 species of macroalgae were obtained. Five seagrass species and five algae species are known to contain compounds that are beneficial to humans such as antibacterial, antifungal, and bioactive compounds. Four algae species are used for consumption. The diversity index values of seagrass and macroalgae obtained were categorized as low-medium, with H’ 1.05 - 1.55 for seagrass and H’ 1.22 - 1.56 for algae. This study provides information that are useful for future utilization of marine resources.
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Vergés, Adriana, Peter D. Steinberg, Mark E. Hay, Alistair G. B. Poore, Alexandra H. Campbell, Enric Ballesteros, Kenneth L. Heck et al. "The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts". Proceedings of the Royal Society B: Biological Sciences 281, n. 1789 (22 agosto 2014): 20140846. http://dx.doi.org/10.1098/rspb.2014.0846.

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Climate-driven changes in biotic interactions can profoundly alter ecological communities, particularly when they impact foundation species. In marine systems, changes in herbivory and the consequent loss of dominant habitat forming species can result in dramatic community phase shifts, such as from coral to macroalgal dominance when tropical fish herbivory decreases, and from algal forests to ‘barrens’ when temperate urchin grazing increases. Here, we propose a novel phase-shift away from macroalgal dominance caused by tropical herbivores extending their range into temperate regions. We argue that this phase shift is facilitated by poleward-flowing boundary currents that are creating ocean warming hotspots around the globe, enabling the range expansion of tropical species and increasing their grazing rates in temperate areas. Overgrazing of temperate macroalgae by tropical herbivorous fishes has already occurred in Japan and the Mediterranean. Emerging evidence suggests similar phenomena are occurring in other temperate regions, with increasing occurrence of tropical fishes on temperate reefs.
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Firdaus, Mochamad Ramdhan, Arief Rachman, Oksto Ridho Sianturi, Diah Anggraini Wulandari, Hanny Meirinawati, Mariana Destila Bayu Intan e Edy Endrotjahyo. "Kelimpahan Dinoflagellata Bentik Berbahaya di Habitat Lamun dan Makroalga di Pulau Pari, Kepulauan Seribu, Indonesia". OLDI (Oseanologi dan Limnologi di Indonesia) 6, n. 3 (27 dicembre 2021): 191. http://dx.doi.org/10.14203/oldi.2021.v6i3.382.

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<p class="Papertext"><strong>The Abundance of the Harmful Benthic Dinoflagellate in the Seagrass and Macroalgae Habitats on Pari Island, Thousand Islands, Indonesia. </strong>Benthic dinoflagellates are an important part of benthic ecosystems and part of their ecological functions. However, ciguatoxin (CTX) producer dinoflagellates, which could cause Ciguatera Fish Poisoning (CFP) disease, is a known threat to marine biota and the island’s coastal communities, such as in Pari Island. Thus, this research aimed is to study the population of five harmful and toxin producer benthic dinoflagellate genera, namely <span style="text-decoration: underline;">Amphidinium</span>, <span style="text-decoration: underline;">Coolia</span>, <span style="text-decoration: underline;">Gambierdiscus</span>, <span style="text-decoration: underline;">Ostreopsis</span>, and <span style="text-decoration: underline;">Prorocentrum</span>, in macroalgae and seagrass habitats of Pari Island. Benthic dinoflagellate samples were collected in Juni 2019 using artificial substrates in the form of a 10×15 cm nylon screen. Environmental variables, such as nutrient concentration (nitrogen and phosphorus) and water temperature were also measured. The results showed that the average benthic dinoflagellate density in seagrass habitats was four times higher compared to the macroalgae habitats. <em>Gambierdiscus</em> were found as the most abundant benthic dinoflagellate in seagrass habitats, while <em>Prorocentrum</em> were more abundant in macroalgae habitats. Principal Component Analysis (PCA) showed that the N:P ratio was the most important regulating parameter for most benthic dinoflagellate genera in this study, except <em>Ostreopsis</em>, which was found to be more abundant in phosphorus-rich macroalga habitats. The data also shows an increase of benthic dinoflagellate cell density up to seven times compared to the previous research data in 2012 and 2013. That trend indicates an increase in the disturbance and pressure on the macroalgae and seagrass habitats of Pari Island, which require special attention to prevent the occurrence of toxic Benthic Harmful Algal Blooms (bHABs) and CFP cases in the island.</p>

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