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Mark E. Hay - One of the best experts on this subject based on the ideXlab platform.
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ME (2010) Impact of herbivore identity on algal succession and coral growth on a Caribbean reef
2016Co-Authors: Deron E. Burkepile, Mark E. HayAbstract:Background: Herbivory is an important top-down force on coral reefs that regulates Macroalgal abundance, mediates competitive interactions between Macroalgae and corals, and provides resilience following disturbances such as hurricanes and coral bleaching. However, reductions in herbivore diversity and abundance via disease or over-fishing may harm corals directly and may indirectly increase coral susceptibility to other disturbances. Methodology and Principal Findings: In two experiments over two years, we enclosed equivalent densities and masses of either single-species or mixed-species of herbivorous fishes in replicate, 4 m2 cages at a depth of 17 m on a reef in the Florida Keys, USA to evaluate the effects of herbivore identity and species richness on colonization and development of Macroalgal communities and the cascading effects of algae on coral growth. In Year 1, we used the redband parrotfish (Sparisoma aurofrenatum) and the ocean surgeonfish (Acanthurus bahianus); in Year 2, we used the redband parrotfish and the princess parrotfish (Scarus taeniopterus). On new substrates, rapid grazing by ocean surgeonfish and princess parrotfish kept communities in an early successional stage dominated by short, filamentous algae and crustose coralline algae that did not suppress coral growth. In contrast, feeding by redband parrotfish allowed an accumulation of tall filaments and later successional Macroalgae that suppressed coral growth. These patterns contrast with patterns from established communities not undergoing primary succession; on established substrates redband parrotfish significantly reduced upright Macroalga
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Seaweed-Coral Interactions: Variance in Seaweed Allelopathy, Coral Susceptibility, and Potential Effects on
2016Co-Authors: Coral Resilience, Roberta M Bonaldo, Mark E. HayAbstract:Tropical reefs are in global decline with seaweeds commonly replacing corals. Negative associations between Macroalgae and corals are well documented, but the mechanisms involved, the dynamics of the interactions, and variance in effects of different Macroalgal-coral pairings are poorly investigated. We assessed the frequency, magnitude, and dynamics of Macroalgal-coral competition involving allelopathic and non-allelopathic Macroalgae on three, spatially grouped pairs of no-take Marine Protected Areas (MPAs) and non-MPAs in Fiji. In non-MPAs, biomass of herbivorous fishes was 70–80% lower, Macroalgal cover 4–9 fold higher, Macroalgal-coral contacts 5–15 fold more frequent and 23–67 fold more extensive (measured as % of colony margin contacted by Macroalgae), and coral cover 51–68 % lower than in MPAs. Coral contacts with allelopathic Macroalgae occurred less frequently than expected by chance across all sites, while contact with non-allelopathic Macroalgae tended to occur more frequently than expected. Transplants of allelopathic Macroalgae (Chlorodesmis fastigiata and Galaxaura filamentosa) against coral edges inflicted damage to Acropora aspera and Pocillopora damicornis more rapidly and extensively than to Porites cylindrica and Porites lobata, which appeared more resistant to these Macroalgae. Montipora digitata experienced intermediate damage. Extent of damage from Macroalgal contact was independent of coral colony size for each of the 10 Macroalgal-coral pairings we established. When natural contacts with Galaxaura filamentosa were removed in the field, recovery was rapid for Porites lobata, but Pocillopora damicornis did no
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seaweed coral interactions variance in seaweed allelopathy coral susceptibility and potential effects on coral resilience
PLOS ONE, 2014Co-Authors: Roberta M Bonaldo, Mark E. HayAbstract:Tropical reefs are in global decline with seaweeds commonly replacing corals. Negative associations between Macroalgae and corals are well documented, but the mechanisms involved, the dynamics of the interactions, and variance in effects of different Macroalgal-coral pairings are poorly investigated. We assessed the frequency, magnitude, and dynamics of Macroalgal-coral competition involving allelopathic and non-allelopathic Macroalgae on three, spatially grouped pairs of no-take Marine Protected Areas (MPAs) and non-MPAs in Fiji. In non-MPAs, biomass of herbivorous fishes was 70–80% lower, Macroalgal cover 4–9 fold higher, Macroalgal-coral contacts 5–15 fold more frequent and 23–67 fold more extensive (measured as % of colony margin contacted by Macroalgae), and coral cover 51–68% lower than in MPAs. Coral contacts with allelopathic Macroalgae occurred less frequently than expected by chance across all sites, while contact with non-allelopathic Macroalgae tended to occur more frequently than expected. Transplants of allelopathic Macroalgae (Chlorodesmis fastigiata and Galaxaura filamentosa) against coral edges inflicted damage to Acropora aspera and Pocillopora damicornis more rapidly and extensively than to Porites cylindrica and Porites lobata, which appeared more resistant to these Macroalgae. Montipora digitata experienced intermediate damage. Extent of damage from Macroalgal contact was independent of coral colony size for each of the 10 Macroalgal-coral pairings we established. When natural contacts with Galaxaura filamentosa were removed in the field, recovery was rapid for Porites lobata, but Pocillopora damicornis did not recover and damage continued to expand. As Macroalgae increase on overfished tropical reefs, allelopathy could produce feedbacks that suppress coral resilience, prevent coral recovery, and promote the stability of algal beds in habitats previously available to corals.
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Gene Expression of Corals in Response to Macroalgal Competitors
2014Co-Authors: Tonya L. Shearer, Terry W. Snell, Mark E. HayAbstract:As corals decline and Macroalgae proliferate on coral reefs, coral-Macroalgal competition becomes more frequent and ecologically important. Whether corals are damaged by these interactions depends on susceptibility of the coral and traits of Macroalgal competitors. Investigating changes in gene expression of corals and their intracellular symbiotic algae, Symbiodinium, in response to contact with different Macroalgae provides insight into the biological processes and cellular pathways affected by competition with Macroalgae. We evaluated the gene expression profiles of coral and Symbiodinium genes from two confamilial corals, Acropora millepora and Montipora digitata, after 6 h and 48 h of contact with four common Macroalgae that differ in their allelopathic potency to corals. Contacts with Macroalgae affected different biological pathways in the more susceptible (A. millepora) versus the more resistant (M. digitata) coral. Genes of coral hosts and of their associated Symbiodinium also responded in species-specific and time-specific ways to each Macroalga. Changes in number and expression intensity of affected genes were greater after 6 h compared to 48 h of contact and were greater following contact with Chlorodesmis fastigiata and Amphiroa crassa than following contact with Galaxaura filamentosa or Turbinaria conoides. We documented a divergence in transcriptional responses between two confamilial corals and their associated Symbiodinium, as well as a diversity of dynamic responses within each coral species with respect to the species of Macroalgal competitor and the duration of exposure to that competitor. These responses included early initiation of immune processes by Montipora, which is more resistant to damage after long-term Macroalgal contact. Activation of the immune response by corals that better resist algal competition is consistent with the hypothesis that some Macroalgal effects on corals may be mediated by microbial pathogens.
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effects of herbivory nutrients and reef protection on algal proliferation and coral growth on a tropical reef
Oecologia, 2012Co-Authors: Douglas B Rasher, Sebastian Engel, Victor Bonito, Gareth J Fraser, Joseph P Montoya, Mark E. HayAbstract:Maintaining coral reef resilience against increasing anthropogenic disturbance is critical for effective reef management. Resilience is partially determined by how processes, such as herbivory and nutrient supply, affect coral recovery versus Macroalgal proliferation following disturbances. However, the relative effects of herbivory versus nutrient enrichment on algal proliferation remain debated. Here, we manipulated herbivory and nutrients on a coral-dominated reef protected from fishing, and on an adjacent Macroalgal-dominated reef subject to fishing and riverine discharge, over 152 days. On both reefs, herbivore exclusion increased total and upright Macroalgal cover by 9–46 times, upright Macroalgal biomass by 23–84 times, and cyanobacteria cover by 0–27 times, but decreased cover of encrusting coralline algae by 46–100% and short turf algae by 14–39%. In contrast, nutrient enrichment had no effect on algal proliferation, but suppressed cover of total Macroalgae (by 33–42%) and cyanobacteria (by 71% on the protected reef) when herbivores were excluded. Herbivore exclusion, but not nutrient enrichment, also increased sediment accumulation, suggesting a strong link between herbivory, Macroalgal growth, and sediment retention. Growth rates of the corals Porites cylindrica and Acropora millepora were 30–35% greater on the protected versus fished reef, but nutrient and herbivore manipulations within a site did not affect coral growth. Cumulatively, these data suggest that herbivory rather than eutrophication plays the dominant role in mediating Macroalgal proliferation, that Macroalgae trap sediments that may further suppress herbivory and enhance Macroalgal dominance, and that corals are relatively resistant to damage from some Macroalgae but are significantly impacted by ambient reef condition.
Xuexi Tang - One of the best experts on this subject based on the ideXlab platform.
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Allelopathic effects of Ulva pertusa, Corallina pilulifera and Sargassum thunbergii on the growth of the dinoflagellates Heterosigma akashiwo
2016Co-Authors: Alexandrium Tamarense, Renjun Wang, Hui Xiao, Peiyu Zhang, Hengjiang Cai, Xuexi TangAbstract:Abstract The allelopathic effects of fresh tissue, dry powder and aqueous extracts of three Macroalgae, Ulva pertusa, Corallina pilulifera and Sargassum thunbergii, on the growth of the dinoflagellates Heterosigma akashiwo and Alexandrium tamarense were evaluated using coexistence culture systems in which concentrations of the three Macroalga were varied. The results of the coexistence assay showed that the growth of the two microalgae was strongly inhibited by using fresh tissue, dry powder and aqueous extracts of the three Macroalga; the allelo-chemicals were lethal to H. akashiwo at relatively higher concentrations of the three Macroalga. The Macroalgae showing the most allelopathic effect on H. akashiwo and A. tamarense using fresh tissue were U. pertusa and S. thunbergii, using dry powder were S. thunbergii and U. pertusa, and using aqueous extracts were U. pertusa and C. pilulifera. We also examined the potential allelopathic effect on the two microalgae of culture filtrate of the three Macroalga; culture medium filtrate initially exhibited no inhibi-tory effects when first added but inhibitory effects became apparent under semi-continuous addition, which suggested that continuous release of small quantities of rapidly degradable allelochemicals from the fresh Macroalgal tissue were essential to effec-tively inhibit the growth of the two microalgae. Key words allelopathic effects. dinoflagellate. seaweed extrac
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effects of three Macroalgae ulva linza chlorophyta corallina pilulifera rhodophyta and sargassum thunbergii phaeophyta on the growth of the red tide microalga prorocentrum donghaiense under laboratory conditions
Journal of Sea Research, 2007Co-Authors: Renjun Wang, Hui Xiao, You Wang, Wenli Zhou, Xuexi TangAbstract:Allelopathic effects of several concentrations of fresh tissue and dry powder of three Macroalgae, Ulva linza, Corallina pilulifera and Sargassum thunbergii, on the red tide microalga Prorocentrum donghaiense were evaluated in microcosms. Preliminary studies on the algicidal effects of one aqueous and four organic solvent extracts from the Macroalgae on the microalga were carried out to confirm the existence of allelochemicals in the tissues of the Macroalgae. The effects of Macroalgal culture medium filtrate on P. donghaiense were investigated using initial or semi-continuous filtrate addition. Furthermore, the potential effects of the microalga on these three Macroalgae were also tested. The results of the microcosm assay showed that the growth of P. donghaiense was strongly inhibited by using fresh tissues and dry powder of the three Macroalgae. Both aqueous and methanol extracts of the Macroalgae had strong growth inhibitory effects on P. donghaiense, while the other three organic solvent extracts (acetone, ether and chloroform) had no apparent effect on its growth; this suggested that the allelochemicals from these three Macroalga had relatively high polarities. The three Macroalgal culture medium filtrates exhibited apparent growth inhibitory effect on the microalgae under initial or semi-continuous addition, which suggested that the cells of P. donghaiense are sensitive to the allelochemicals. In contrast, P. donghaiense had no apparent effect on the growth of the Macroalgae in coexistence experiment.
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comparative studies on the allelopathic effects of ulva pertusa kjellml corallina pilulifera postl et ruprl and sargassum thunbergii mertl o kuntze on skeletonema costatum grev cleve
Journal of Integrative Plant Biology, 2006Co-Authors: Renjun Wang, Hui Xiao, Peiyu Zhang, Hengjiang Cai, Xuexi TangAbstract:In the present study, we evaluated the allelopathic effects of three Macroalgae, namely Ulva pertusa Kjellml, Corallina pilulifera Postl et Ruprl, and Sargassum thunbergii Mertl O. Kuntze, on the growth of the microalga Skeletonema costatum (Grev.) Creve using culture systems in which the algae coexisted. The effects of the Macroalgal culture medium filtrate on S. costatum were also investigated. Moreover, isolated co-culture systems were built to confirm the existence of allelochemicals and preclude growth inhibition by direct contact. The coexistence assay data demonstrated that the growth of S. costatum was strongly inhibited when fresh tissues, dry powder and aqueous extracts were used; the allelochemicals were lethal to S. costatum at relatively higher concentrations. The effects of the Macroalgal culture medium filtrate on the microalga showed both species specificity and complexity. The inhibitory effect of fresh Macroalgal tissue and culture medium filtrate on the microalga was due to the alleochemicals released by the Macroalgae. The results of the present study show that the allelopathic effects of Macroalgae on the microalga are complex. The present study could shed light onto the basis of the interaction between macro-and microalgae. (Managing editor: Ping He)
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Allelopathic effects of Ulva pertusa , Corallina pilulifera and Sargassum thunbergii on the growth of the dinoflagellates Heterosigma akashiwo and Alexandrium tamarense
Journal of applied phycology, 2006Co-Authors: Renjun Wang, Hui Xiao, Peiyu Zhang, Hengjiang Cai, Xuexi TangAbstract:The allelopathic effects of fresh tissue, dry powder and aqueous extracts of three Macroalgae, Ulva pertusa, Corallina pilulifera and Sargassum thunbergii, on the growth of the dinoflagellates Heterosigma akashiwo and Alexandrium tamarense were evaluated using coexistence culture systems in which concentrations of the three Macroalga were varied. The results of the coexistence assay showed that the growth of the two microalgae was strongly inhibited by using fresh tissue, dry powder and aqueous extracts of the three Macroalga; the allelochemicals were lethal to H. akashiwo at relatively higher concentrations of the three Macroalga. The Macroalgae showing the most allelopathic effect on H. akashiwo and A. tamarense using fresh tissue were U. pertusa and S. thunbergii, using dry powder were S. thunbergii and U. pertusa, and using aqueous extracts were U. pertusa and C. pilulifera. We also examined the potential allelopathic effect on the two microalgae of culture filtrate of the three Macroalga; culture medium filtrate initially exhibited no inhibitory effects when first added but inhibitory effects became apparent under semi-continuous addition, which suggested that continuous release of small quantities of rapidly degradable allelochemicals from the fresh Macroalgal tissue were essential to effectively inhibit the growth of the two microalgae.
Renjun Wang - One of the best experts on this subject based on the ideXlab platform.
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Allelopathic effects of Ulva pertusa, Corallina pilulifera and Sargassum thunbergii on the growth of the dinoflagellates Heterosigma akashiwo
2016Co-Authors: Alexandrium Tamarense, Renjun Wang, Hui Xiao, Peiyu Zhang, Hengjiang Cai, Xuexi TangAbstract:Abstract The allelopathic effects of fresh tissue, dry powder and aqueous extracts of three Macroalgae, Ulva pertusa, Corallina pilulifera and Sargassum thunbergii, on the growth of the dinoflagellates Heterosigma akashiwo and Alexandrium tamarense were evaluated using coexistence culture systems in which concentrations of the three Macroalga were varied. The results of the coexistence assay showed that the growth of the two microalgae was strongly inhibited by using fresh tissue, dry powder and aqueous extracts of the three Macroalga; the allelo-chemicals were lethal to H. akashiwo at relatively higher concentrations of the three Macroalga. The Macroalgae showing the most allelopathic effect on H. akashiwo and A. tamarense using fresh tissue were U. pertusa and S. thunbergii, using dry powder were S. thunbergii and U. pertusa, and using aqueous extracts were U. pertusa and C. pilulifera. We also examined the potential allelopathic effect on the two microalgae of culture filtrate of the three Macroalga; culture medium filtrate initially exhibited no inhibi-tory effects when first added but inhibitory effects became apparent under semi-continuous addition, which suggested that continuous release of small quantities of rapidly degradable allelochemicals from the fresh Macroalgal tissue were essential to effec-tively inhibit the growth of the two microalgae. Key words allelopathic effects. dinoflagellate. seaweed extrac
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effects of three Macroalgae ulva linza chlorophyta corallina pilulifera rhodophyta and sargassum thunbergii phaeophyta on the growth of the red tide microalga prorocentrum donghaiense under laboratory conditions
Journal of Sea Research, 2007Co-Authors: Renjun Wang, Hui Xiao, You Wang, Wenli Zhou, Xuexi TangAbstract:Allelopathic effects of several concentrations of fresh tissue and dry powder of three Macroalgae, Ulva linza, Corallina pilulifera and Sargassum thunbergii, on the red tide microalga Prorocentrum donghaiense were evaluated in microcosms. Preliminary studies on the algicidal effects of one aqueous and four organic solvent extracts from the Macroalgae on the microalga were carried out to confirm the existence of allelochemicals in the tissues of the Macroalgae. The effects of Macroalgal culture medium filtrate on P. donghaiense were investigated using initial or semi-continuous filtrate addition. Furthermore, the potential effects of the microalga on these three Macroalgae were also tested. The results of the microcosm assay showed that the growth of P. donghaiense was strongly inhibited by using fresh tissues and dry powder of the three Macroalgae. Both aqueous and methanol extracts of the Macroalgae had strong growth inhibitory effects on P. donghaiense, while the other three organic solvent extracts (acetone, ether and chloroform) had no apparent effect on its growth; this suggested that the allelochemicals from these three Macroalga had relatively high polarities. The three Macroalgal culture medium filtrates exhibited apparent growth inhibitory effect on the microalgae under initial or semi-continuous addition, which suggested that the cells of P. donghaiense are sensitive to the allelochemicals. In contrast, P. donghaiense had no apparent effect on the growth of the Macroalgae in coexistence experiment.
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comparative studies on the allelopathic effects of ulva pertusa kjellml corallina pilulifera postl et ruprl and sargassum thunbergii mertl o kuntze on skeletonema costatum grev cleve
Journal of Integrative Plant Biology, 2006Co-Authors: Renjun Wang, Hui Xiao, Peiyu Zhang, Hengjiang Cai, Xuexi TangAbstract:In the present study, we evaluated the allelopathic effects of three Macroalgae, namely Ulva pertusa Kjellml, Corallina pilulifera Postl et Ruprl, and Sargassum thunbergii Mertl O. Kuntze, on the growth of the microalga Skeletonema costatum (Grev.) Creve using culture systems in which the algae coexisted. The effects of the Macroalgal culture medium filtrate on S. costatum were also investigated. Moreover, isolated co-culture systems were built to confirm the existence of allelochemicals and preclude growth inhibition by direct contact. The coexistence assay data demonstrated that the growth of S. costatum was strongly inhibited when fresh tissues, dry powder and aqueous extracts were used; the allelochemicals were lethal to S. costatum at relatively higher concentrations. The effects of the Macroalgal culture medium filtrate on the microalga showed both species specificity and complexity. The inhibitory effect of fresh Macroalgal tissue and culture medium filtrate on the microalga was due to the alleochemicals released by the Macroalgae. The results of the present study show that the allelopathic effects of Macroalgae on the microalga are complex. The present study could shed light onto the basis of the interaction between macro-and microalgae. (Managing editor: Ping He)
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Allelopathic effects of Ulva pertusa , Corallina pilulifera and Sargassum thunbergii on the growth of the dinoflagellates Heterosigma akashiwo and Alexandrium tamarense
Journal of applied phycology, 2006Co-Authors: Renjun Wang, Hui Xiao, Peiyu Zhang, Hengjiang Cai, Xuexi TangAbstract:The allelopathic effects of fresh tissue, dry powder and aqueous extracts of three Macroalgae, Ulva pertusa, Corallina pilulifera and Sargassum thunbergii, on the growth of the dinoflagellates Heterosigma akashiwo and Alexandrium tamarense were evaluated using coexistence culture systems in which concentrations of the three Macroalga were varied. The results of the coexistence assay showed that the growth of the two microalgae was strongly inhibited by using fresh tissue, dry powder and aqueous extracts of the three Macroalga; the allelochemicals were lethal to H. akashiwo at relatively higher concentrations of the three Macroalga. The Macroalgae showing the most allelopathic effect on H. akashiwo and A. tamarense using fresh tissue were U. pertusa and S. thunbergii, using dry powder were S. thunbergii and U. pertusa, and using aqueous extracts were U. pertusa and C. pilulifera. We also examined the potential allelopathic effect on the two microalgae of culture filtrate of the three Macroalga; culture medium filtrate initially exhibited no inhibitory effects when first added but inhibitory effects became apparent under semi-continuous addition, which suggested that continuous release of small quantities of rapidly degradable allelochemicals from the fresh Macroalgal tissue were essential to effectively inhibit the growth of the two microalgae.
Andrew S. Hoey - One of the best experts on this subject based on the ideXlab platform.
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consumer diversity interacts with prey defenses to drive ecosystem function
Ecology, 2013Co-Authors: Douglas B Rasher, Andrew S. HoeyAbstract:Prey traits linking consumer diversity to ecosystem function remain poorly understood. On tropical coral reefs, herbivores promote coral dominance by suppressing competing Macroalgae, but the roles of herbivore identity and diversity, Macroalgal defenses, and their interactions in affecting reef resilience and function are unclear. We studied adjacent pairs of no-take marine reserves and fished areas on reefs in Fiji and found that protected reefs supported 7–17× greater biomass, 2–3× higher species richness of herbivorous fishes, and 3–11× more live coral cover than did fished reefs. In contrast, Macroalgae were 27–61× more abundant and 3–4× more species-rich on fished reefs. When we transplanted seven common Macroalgae from fished reefs into reserves they were rapidly consumed, suggesting that rates of herbivory (ecosystem functioning) differed inside vs. outside reserves. We then video-recorded feeding activity on the same seven Macroalgae when transplanted into reserves, and assessed the functional redundancy vs. complementarity of herbivorous fishes consuming these Macroalgae. Of 29 species of larger herbivorous fishes on these reefs, only four species accounted for 97% of Macroalgal consumption. Two unicornfish consumed a range of brown Macroalgae, a parrotfish consumed multiple red algae, and a rabbitfish consumed a green alga, with almost no diet overlap among these groups. The two most chemically rich, allelopathic algae were each consumed by a single, but different, fish species. This striking complementarity resulted from herbivore species differing in their tolerances to Macroalgal chemical and structural defenses. A model of assemblage diet breadth based on our feeding observations predicted that high browser diversity would be required for effective control of Macroalgae on Fijian reefs. In support of this model, we observed strong negative relationships between herbivore diversity and Macroalgal abundance and diversity across the six study reefs. Our findings indicate that the total diet breadth of the herbivore community and the probability of all Macroalgae being removed from reefs by herbivores increases with increasing herbivore diversity, but that a few critical species drive this relationship. Therefore, interactions between algal defenses and herbivore tolerances create an essential role for consumer diversity in the functioning and resilience of coral reefs.
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suppression of herbivory by Macroalgal density a critical feedback on coral reefs
Ecology Letters, 2011Co-Authors: Andrew S. HoeyAbstract:Coral reefs globally are in decline, with some reefs undergoing phase shifts from coral-dominance to degraded states dominated by large fleshy Macroalgae. These shifts have been underpinned by the overharvesting of herbivorous fishes and represent a fundamental change in the physical structure of these reefs. Although the physical structure provided by corals is regarded as a key feature that facilitates herbivore activity, the influence of the physical structure of Macroalgal stands is largely unknown. Using transplanted Sargassum, the largest coral reef Macroalga, we created habitat patches of predetermined Macroalgal density (0.25–6.23 kg m−2). Remote video cameras revealed both grazing and browsing fishes avoided high density patches, preferring relatively open areas with low Macroalgal cover. This behaviour may provide a positive feedback leading to the growth and persistence of Macroalgal stands; increasing the stability of phase shifts to Macroalgae.
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limited functional redundancy in a high diversity system single species dominates key ecological process on coral reefs
Ecosystems, 2009Co-Authors: Andrew S. Hoey, David R. BellwoodAbstract:Herbivory is a key process structuring plant communities in both terrestrial and aquatic ecosystems, with variation in herbivory often being related to shifts between alternate states. On coral reefs, regional reductions in herbivores have underpinned shifts from coral to dominance by leathery Macroalgae. These shifts appear difficult to reverse as these Macroalgae are unpalatable to the majority of herbivores, and the Macroalgae suppress the recruitment and growth of corals. The removal of Macroalgae is, therefore, viewed as a key ecological process on coral reefs. On the Great Barrier Reef, Sargassum is a dominant Macroalgal species following experimentally induced coral–Macroalgal phase-shifts. We, therefore, used Sargassum assays and remote video cameras to directly quantify the species responsible for removing Macroalgae across a range of coral reef habitats on Lizard Island, northern Great Barrier Reef. Despite supporting over 50 herbivorous fish species and six Macroalgal browsing species, the video footage revealed that a single species, Naso unicornis, was almost solely responsible for the removal of Sargassum biomass across all habitats. Of the 42,246 bites taken from the Sargassum across all habitats, N. unicornis accounted for 89.8% (37,982) of the total bites, and 94.6% of the total mass standardized bites. This limited redundancy, both within and across local scales, underscores the need to assess the functional roles of individual species. Management and conservation strategies may need to look beyond the preservation of species diversity and focus on the maintenance of ecological processes and the protection of key species in critical functional groups.
Hui Xiao - One of the best experts on this subject based on the ideXlab platform.
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Allelopathic effects of Ulva pertusa, Corallina pilulifera and Sargassum thunbergii on the growth of the dinoflagellates Heterosigma akashiwo
2016Co-Authors: Alexandrium Tamarense, Renjun Wang, Hui Xiao, Peiyu Zhang, Hengjiang Cai, Xuexi TangAbstract:Abstract The allelopathic effects of fresh tissue, dry powder and aqueous extracts of three Macroalgae, Ulva pertusa, Corallina pilulifera and Sargassum thunbergii, on the growth of the dinoflagellates Heterosigma akashiwo and Alexandrium tamarense were evaluated using coexistence culture systems in which concentrations of the three Macroalga were varied. The results of the coexistence assay showed that the growth of the two microalgae was strongly inhibited by using fresh tissue, dry powder and aqueous extracts of the three Macroalga; the allelo-chemicals were lethal to H. akashiwo at relatively higher concentrations of the three Macroalga. The Macroalgae showing the most allelopathic effect on H. akashiwo and A. tamarense using fresh tissue were U. pertusa and S. thunbergii, using dry powder were S. thunbergii and U. pertusa, and using aqueous extracts were U. pertusa and C. pilulifera. We also examined the potential allelopathic effect on the two microalgae of culture filtrate of the three Macroalga; culture medium filtrate initially exhibited no inhibi-tory effects when first added but inhibitory effects became apparent under semi-continuous addition, which suggested that continuous release of small quantities of rapidly degradable allelochemicals from the fresh Macroalgal tissue were essential to effec-tively inhibit the growth of the two microalgae. Key words allelopathic effects. dinoflagellate. seaweed extrac
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effects of three Macroalgae ulva linza chlorophyta corallina pilulifera rhodophyta and sargassum thunbergii phaeophyta on the growth of the red tide microalga prorocentrum donghaiense under laboratory conditions
Journal of Sea Research, 2007Co-Authors: Renjun Wang, Hui Xiao, You Wang, Wenli Zhou, Xuexi TangAbstract:Allelopathic effects of several concentrations of fresh tissue and dry powder of three Macroalgae, Ulva linza, Corallina pilulifera and Sargassum thunbergii, on the red tide microalga Prorocentrum donghaiense were evaluated in microcosms. Preliminary studies on the algicidal effects of one aqueous and four organic solvent extracts from the Macroalgae on the microalga were carried out to confirm the existence of allelochemicals in the tissues of the Macroalgae. The effects of Macroalgal culture medium filtrate on P. donghaiense were investigated using initial or semi-continuous filtrate addition. Furthermore, the potential effects of the microalga on these three Macroalgae were also tested. The results of the microcosm assay showed that the growth of P. donghaiense was strongly inhibited by using fresh tissues and dry powder of the three Macroalgae. Both aqueous and methanol extracts of the Macroalgae had strong growth inhibitory effects on P. donghaiense, while the other three organic solvent extracts (acetone, ether and chloroform) had no apparent effect on its growth; this suggested that the allelochemicals from these three Macroalga had relatively high polarities. The three Macroalgal culture medium filtrates exhibited apparent growth inhibitory effect on the microalgae under initial or semi-continuous addition, which suggested that the cells of P. donghaiense are sensitive to the allelochemicals. In contrast, P. donghaiense had no apparent effect on the growth of the Macroalgae in coexistence experiment.
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comparative studies on the allelopathic effects of ulva pertusa kjellml corallina pilulifera postl et ruprl and sargassum thunbergii mertl o kuntze on skeletonema costatum grev cleve
Journal of Integrative Plant Biology, 2006Co-Authors: Renjun Wang, Hui Xiao, Peiyu Zhang, Hengjiang Cai, Xuexi TangAbstract:In the present study, we evaluated the allelopathic effects of three Macroalgae, namely Ulva pertusa Kjellml, Corallina pilulifera Postl et Ruprl, and Sargassum thunbergii Mertl O. Kuntze, on the growth of the microalga Skeletonema costatum (Grev.) Creve using culture systems in which the algae coexisted. The effects of the Macroalgal culture medium filtrate on S. costatum were also investigated. Moreover, isolated co-culture systems were built to confirm the existence of allelochemicals and preclude growth inhibition by direct contact. The coexistence assay data demonstrated that the growth of S. costatum was strongly inhibited when fresh tissues, dry powder and aqueous extracts were used; the allelochemicals were lethal to S. costatum at relatively higher concentrations. The effects of the Macroalgal culture medium filtrate on the microalga showed both species specificity and complexity. The inhibitory effect of fresh Macroalgal tissue and culture medium filtrate on the microalga was due to the alleochemicals released by the Macroalgae. The results of the present study show that the allelopathic effects of Macroalgae on the microalga are complex. The present study could shed light onto the basis of the interaction between macro-and microalgae. (Managing editor: Ping He)
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Allelopathic effects of Ulva pertusa , Corallina pilulifera and Sargassum thunbergii on the growth of the dinoflagellates Heterosigma akashiwo and Alexandrium tamarense
Journal of applied phycology, 2006Co-Authors: Renjun Wang, Hui Xiao, Peiyu Zhang, Hengjiang Cai, Xuexi TangAbstract:The allelopathic effects of fresh tissue, dry powder and aqueous extracts of three Macroalgae, Ulva pertusa, Corallina pilulifera and Sargassum thunbergii, on the growth of the dinoflagellates Heterosigma akashiwo and Alexandrium tamarense were evaluated using coexistence culture systems in which concentrations of the three Macroalga were varied. The results of the coexistence assay showed that the growth of the two microalgae was strongly inhibited by using fresh tissue, dry powder and aqueous extracts of the three Macroalga; the allelochemicals were lethal to H. akashiwo at relatively higher concentrations of the three Macroalga. The Macroalgae showing the most allelopathic effect on H. akashiwo and A. tamarense using fresh tissue were U. pertusa and S. thunbergii, using dry powder were S. thunbergii and U. pertusa, and using aqueous extracts were U. pertusa and C. pilulifera. We also examined the potential allelopathic effect on the two microalgae of culture filtrate of the three Macroalga; culture medium filtrate initially exhibited no inhibitory effects when first added but inhibitory effects became apparent under semi-continuous addition, which suggested that continuous release of small quantities of rapidly degradable allelochemicals from the fresh Macroalgal tissue were essential to effectively inhibit the growth of the two microalgae.
