Pub Date : 2024-06-26DOI: 10.1007/s10021-024-00920-1
Grégoire Saboret, Coralie Moccetti, Kunio Takatsu, David J. Janssen, Blake Matthews, Jakob Brodersen, Carsten J. Schubert
In a warming world, the input of glacier meltwater to inland water ecosystems is predicted to change, potentially affecting their productivity. Meta-ecosystem theory, which posits that the nutrient availability in the recipient ecosystem can determine the extent of cross-ecosystem boundary utilization, can be useful for studying landscape-scale influences of glacier meltwater on inland waters. Here, we investigate how the input of glacier meltwater in a river system in Southern Greenland influences the utilization of marine subsidies in freshwater fish. Our study system comprised four sites, with controls for glacial meltwater and marine subsidies, harboring a partially migrating population of arctic char, meaning that some individuals migrate to the ocean and others remain in freshwaters, and two fully resident populations as a freshwater reference. We assessed the incorporation of marine carbon in freshwater resident char using both bulk and amino acid stable isotope analysis of muscle tissue. In the population with partial migration, marine subsidies were a significant resource for resident char individuals, and estimates of trophic position suggest that egg cannibalism is an important mechanism underlying the assimilation of these marine subsidies. In proglacial streams, namely those with high glacial meltwater, the total dependence on marine subsidies increased and reached 83% because char become cannibals at smaller sizes. In the configuration of our focal meta-ecosystem, our results suggest that the importance of marine subsidies to freshwater fish strengthens within increasing meltwater flux from upstream glaciers.
{"title":"Glacial Meltwater Increases the Dependence on Marine Subsidies of Fish in Freshwater Ecosystems","authors":"Grégoire Saboret, Coralie Moccetti, Kunio Takatsu, David J. Janssen, Blake Matthews, Jakob Brodersen, Carsten J. Schubert","doi":"10.1007/s10021-024-00920-1","DOIUrl":"https://doi.org/10.1007/s10021-024-00920-1","url":null,"abstract":"<p>In a warming world, the input of glacier meltwater to inland water ecosystems is predicted to change, potentially affecting their productivity. Meta-ecosystem theory, which posits that the nutrient availability in the recipient ecosystem can determine the extent of cross-ecosystem boundary utilization, can be useful for studying landscape-scale influences of glacier meltwater on inland waters. Here, we investigate how the input of glacier meltwater in a river system in Southern Greenland influences the utilization of marine subsidies in freshwater fish. Our study system comprised four sites, with controls for glacial meltwater and marine subsidies, harboring a partially migrating population of arctic char, meaning that some individuals migrate to the ocean and others remain in freshwaters, and two fully resident populations as a freshwater reference. We assessed the incorporation of marine carbon in freshwater resident char using both bulk and amino acid stable isotope analysis of muscle tissue. In the population with partial migration, marine subsidies were a significant resource for resident char individuals, and estimates of trophic position suggest that egg cannibalism is an important mechanism underlying the assimilation of these marine subsidies. In proglacial streams, namely those with high glacial meltwater, the total dependence on marine subsidies increased and reached 83% because char become cannibals at smaller sizes. In the configuration of our focal meta-ecosystem, our results suggest that the importance of marine subsidies to freshwater fish strengthens within increasing meltwater flux from upstream glaciers.</p>","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141501437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-13DOI: 10.1007/s10021-024-00917-w
Li Yuen Chiew, J. Brodie, D. Burslem, Glen Reynolds, C. Vairappan, Eleanor M. Slade
{"title":"Invertebrate-Mediated Ecosystem Processes are Resilient to Disturbance Across a Land-Use Gradient in Borneo","authors":"Li Yuen Chiew, J. Brodie, D. Burslem, Glen Reynolds, C. Vairappan, Eleanor M. Slade","doi":"10.1007/s10021-024-00917-w","DOIUrl":"https://doi.org/10.1007/s10021-024-00917-w","url":null,"abstract":"","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141347705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-12DOI: 10.1007/s10021-024-00915-y
A. Spînu, M. A. Nicolaie, T. Asbeck, D. Kozák, Y. Paillet, E. Cateau, M. Mikoláš, M. Svoboda, J. Bauhus
{"title":"Temporal Development of Microhabitats on Living Habitat Trees in Temperate European Forests","authors":"A. Spînu, M. A. Nicolaie, T. Asbeck, D. Kozák, Y. Paillet, E. Cateau, M. Mikoláš, M. Svoboda, J. Bauhus","doi":"10.1007/s10021-024-00915-y","DOIUrl":"https://doi.org/10.1007/s10021-024-00915-y","url":null,"abstract":"","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141350391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-12DOI: 10.1007/s10021-024-00914-z
R. Ochoa-Hueso, Juan Piñeiro, Lidia Gómez Morán, L. Serrano‐Grijalva, Sally A. Power
{"title":"Plant Multi-element Coupling as an Indicator of Nutritional Mismatches Under Global Change","authors":"R. Ochoa-Hueso, Juan Piñeiro, Lidia Gómez Morán, L. Serrano‐Grijalva, Sally A. Power","doi":"10.1007/s10021-024-00914-z","DOIUrl":"https://doi.org/10.1007/s10021-024-00914-z","url":null,"abstract":"","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141351784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-05DOI: 10.1007/s10021-024-00918-9
C. Troche-Souza, Á. Priego-Santander, Julián Equihua, B. Vázquez-Balderas
{"title":"Spatial Distribution of Carbon Stocks Along Protected and Non-protected Coastal Wetland Ecosystems in the Gulf of Mexico","authors":"C. Troche-Souza, Á. Priego-Santander, Julián Equihua, B. Vázquez-Balderas","doi":"10.1007/s10021-024-00918-9","DOIUrl":"https://doi.org/10.1007/s10021-024-00918-9","url":null,"abstract":"","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141383461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-28DOI: 10.1007/s10021-024-00913-0
H. D. Alexander, A. K. Paulson, M. M. Loranty, M. C. Mack, S. M. Natali, H. Pena, S. Davydov, V. Spektor, N. Zimov
With climate warming and drying, fire activity is increasing in Cajander larch (Larix cajanderi Mayr.) forests underlain by continuous permafrost in northeastern Siberia, and initial post-fire tree demographic processes could unfold to determine long-term forest carbon (C) dynamics through impacts on tree density. Here, we evaluated above- and belowground C pools across 25 even-aged larch stands of varying tree densities that established following a wildfire in ~ 1940 near Cherskiy, Russia. Total C pools increased with increased larch tree density, from ~ 9,000 g C m−2 in low-density stands to ~ 11,000 g C m−2 in high and very high-density stands, with increases most pronounced at tree densities < 1 stem m−2 and driven by increased above- and belowground (that is, coarse roots) and live and dead (that is, woody debris and snags) larch biomass. Total understory vegetation and non-larch coarse root C pools declined with increased tree density due to decreased shrub C pools, but these pools were relatively small compared to larch biomass. Fine root, soil organic matter (OM), and near surface (0–30 cm) mineral soil (MS) C pools varied little with tree density, although soil C pools held most (18–28% in OM and 44–51% in MS) C stored in these stands. Thus, if changing fire regimes promote denser stands, C storage will likely increase, but whether this increase offsets C lost during fires remains unknown. Our findings highlight how post-fire tree demographic processes impact C pool distribution and stability in larch forests of Siberian permafrost regions.
随着气候变暖和干燥,西伯利亚东北部连续冻土层下的卡让德落叶松(Larix cajanderi Mayr.)森林的火灾活动日益频繁,火灾后最初的树木分布过程可能会通过对树木密度的影响来决定长期的森林碳(C)动态。在这里,我们评估了俄罗斯切尔斯基附近约 1940 年野火后形成的 25 个不同树木密度的匀龄落叶松林的地上和地下碳库。总碳库随着落叶松树木密度的增加而增加,从低密度林分的 ~ 9,000 g C m-2 增加到高密度和超高密度林分的 ~ 11,000 g C m-2,在树木密度大于或等于 1 干 m-2 时,总碳库的增加最为明显,其驱动力是地上和地下(即粗根)以及活的和死的(即木质碎屑和木渣)落叶松生物量的增加。由于灌木碳库的减少,林下植被和非落叶松粗根的总碳库随着树木密度的增加而减少,但与落叶松生物量相比,这些碳库相对较小。细根、土壤有机质(OM)和近地表(0-30 厘米)矿质土壤(MS)的碳库随树木密度的变化很小,尽管土壤碳库在这些林分中储存了大部分(OM 为 18-28%,MS 为 44-51%)的碳。因此,如果火灾制度的改变促进了林分密度的提高,那么碳储量可能会增加,但这种增加是否能抵消火灾中损失的碳仍是未知数。我们的研究结果突显了火灾后树木的生长过程如何影响西伯利亚永久冻土地区落叶松林中碳库的分布和稳定性。
{"title":"Linking Post-fire Tree Density to Carbon Storage in High-Latitude Cajander Larch (Larix cajanderi) Forests of Far Northeastern Siberia","authors":"H. D. Alexander, A. K. Paulson, M. M. Loranty, M. C. Mack, S. M. Natali, H. Pena, S. Davydov, V. Spektor, N. Zimov","doi":"10.1007/s10021-024-00913-0","DOIUrl":"https://doi.org/10.1007/s10021-024-00913-0","url":null,"abstract":"<p>With climate warming and drying, fire activity is increasing in Cajander larch (<i>Larix cajanderi</i> Mayr.) forests underlain by continuous permafrost in northeastern Siberia, and initial post-fire tree demographic processes could unfold to determine long-term forest carbon (C) dynamics through impacts on tree density. Here, we evaluated above- and belowground C pools across 25 even-aged larch stands of varying tree densities that established following a wildfire in ~ 1940 near Cherskiy, Russia. Total C pools increased with increased larch tree density, from ~ 9,000 g C m<sup>−2</sup> in low-density stands to ~ 11,000 g C m<sup>−2</sup> in high and very high-density stands, with increases most pronounced at tree densities < 1 stem m<sup>−2</sup> and driven by increased above- and belowground (that is, coarse roots) and live and dead (that is, woody debris and snags) larch biomass. Total understory vegetation and non-larch coarse root C pools declined with increased tree density due to decreased shrub C pools, but these pools were relatively small compared to larch biomass. Fine root, soil organic matter (OM), and near surface (0–30 cm) mineral soil (MS) C pools varied little with tree density, although soil C pools held most (18–28% in OM and 44–51% in MS) C stored in these stands. Thus, if changing fire regimes promote denser stands, C storage will likely increase, but whether this increase offsets C lost during fires remains unknown. Our findings highlight how post-fire tree demographic processes impact C pool distribution and stability in larch forests of Siberian permafrost regions.</p>","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141171554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-23DOI: 10.1007/s10021-024-00904-1
A. Campeau, H. He, J. Riml, E. Humphreys, M. Dalva, N. Roulet
{"title":"Wind as a Driver of Peat CO2 Dynamics in a Northern Bog","authors":"A. Campeau, H. He, J. Riml, E. Humphreys, M. Dalva, N. Roulet","doi":"10.1007/s10021-024-00904-1","DOIUrl":"https://doi.org/10.1007/s10021-024-00904-1","url":null,"abstract":"","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141103097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-14DOI: 10.1007/s10021-024-00911-2
Kevin G. Willson, M. Hurteau
{"title":"Abiotic Factors Modify Ponderosa Pine Regeneration Outcomes After High-Severity Fire","authors":"Kevin G. Willson, M. Hurteau","doi":"10.1007/s10021-024-00911-2","DOIUrl":"https://doi.org/10.1007/s10021-024-00911-2","url":null,"abstract":"","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140979607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-13DOI: 10.1007/s10021-024-00908-x
Leighton King, Giulia Wienhues, Pavani Misra, Wojciech Tylmann, Andrea Lami, Stefano M. Bernasconi, Madalina Jaggi, Colin Courtney-Mustaphi, Moritz Muschick, Nare Ngoepe, Salome Mwaiko, Mary A. Kishe, Andrew Cohen, Oliver Heiri, Ole Seehausen, Hendrik Vogel, Martin Grosjean, Blake Matthews
Discerning ecosystem change and food web dynamics underlying anthropogenic eutrophication and the introduction of non-native species is necessary for ensuring the long-term sustainability of fisheries and lake biodiversity. Previous studies of eutrophication in Lake Victoria, eastern Africa, have focused on the loss of endemic fish biodiversity over the past several decades, but changes in the plankton communities over this same time remain unclear. To fill this gap, we examined sediment cores from a eutrophic embayment, Mwanza Gulf, to determine the timing and magnitude of changes in the phytoplankton and zooplankton assemblages over the past century. Biogeochemical proxies indicate nutrient enrichment began around ~ 1920 CE and led to rapid increases in primary production, and our analysis of photosynthetic pigments revealed three zones: pre-eutrophication (prior to 1920 CE), onset of eutrophication with increases in all pigments (1920–1990 CE), and sustained eutrophication with cyanobacterial dominance (1990 CE–present). Cladoceran remains indicate an abrupt decline in biomass in ~ 1960 CE, in response to the cumulative effects of eutrophication and lake-level rise, preceding the collapse of haplochromine cichlids in the 1980s. Alona and Chydorus, typically benthic littoral taxa, have remained at relatively low abundances since the 1960s, whereas the abundance of Bosmina, typically a planktonic taxon, increased in the 1990s concurrently with the biomass recovery of haplochromine cichlid fishes. Overall, our results demonstrate substantial changes over the past century in the biomass structure and taxonomic composition of Mwanza Gulf phytoplankton and zooplankton communities, providing a historical food web perspective that can help understand the recent changes and inform future resource management decisions in the Lake Victoria ecosystem.
{"title":"Anthropogenic Eutrophication Drives Major Food Web Changes in Mwanza Gulf, Lake Victoria","authors":"Leighton King, Giulia Wienhues, Pavani Misra, Wojciech Tylmann, Andrea Lami, Stefano M. Bernasconi, Madalina Jaggi, Colin Courtney-Mustaphi, Moritz Muschick, Nare Ngoepe, Salome Mwaiko, Mary A. Kishe, Andrew Cohen, Oliver Heiri, Ole Seehausen, Hendrik Vogel, Martin Grosjean, Blake Matthews","doi":"10.1007/s10021-024-00908-x","DOIUrl":"https://doi.org/10.1007/s10021-024-00908-x","url":null,"abstract":"<p>Discerning ecosystem change and food web dynamics underlying anthropogenic eutrophication and the introduction of non-native species is necessary for ensuring the long-term sustainability of fisheries and lake biodiversity. Previous studies of eutrophication in Lake Victoria, eastern Africa, have focused on the loss of endemic fish biodiversity over the past several decades, but changes in the plankton communities over this same time remain unclear. To fill this gap, we examined sediment cores from a eutrophic embayment, Mwanza Gulf, to determine the timing and magnitude of changes in the phytoplankton and zooplankton assemblages over the past century. Biogeochemical proxies indicate nutrient enrichment began around ~ 1920 CE and led to rapid increases in primary production, and our analysis of photosynthetic pigments revealed three zones: pre-eutrophication (prior to 1920 CE), onset of eutrophication with increases in all pigments (1920–1990 CE), and sustained eutrophication with cyanobacterial dominance (1990 CE–present). Cladoceran remains indicate an abrupt decline in biomass in ~ 1960 CE, in response to the cumulative effects of eutrophication and lake-level rise, preceding the collapse of haplochromine cichlids in the 1980s. <i>Alona</i> and <i>Chydorus</i>, typically benthic littoral taxa, have remained at relatively low abundances since the 1960s, whereas the abundance of <i>Bosmina,</i> typically a planktonic taxon, increased in the 1990s concurrently with the biomass recovery of haplochromine cichlid fishes. Overall, our results demonstrate substantial changes over the past century in the biomass structure and taxonomic composition of Mwanza Gulf phytoplankton and zooplankton communities, providing a historical food web perspective that can help understand the recent changes and inform future resource management decisions in the Lake Victoria ecosystem.</p>","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140927102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-10DOI: 10.1007/s10021-024-00909-w
Isis Gabriela Martínez López, Luuk Leemans, Marieke M. van Katwijk, S. Valery Ávila-Mosqueda, Brigitta I. van Tussenbroek
Interactions such as mutualism and facilitation are common in ecosystems established by foundation species; however, their outcomes vary and show conditionality. In a Mexican Caribbean Bay, a seagrass-coralline algae (rhodoliths) mutualism protects the seagrass Thalassia testudinum from green turtle overgrazing. We postulate that the state of the seagrass meadow in this bay depends on the strengths of the interactions among seagrasses, green turtles, and coralline algae. Spatio-temporal changes through satellite imagery showed rhodolith bed developed rapidly from 2009 (undetected) to 2016 (bed of 6934 m2). Typically, such rapid expansion of the rhodoliths does not occur in seagrass meadows. An in situ growth experiment of coralline algae showed that a combination of reduction in light and wave movement (usual in dense seagrass meadows) significantly reduced their growth rates. In the rhodolith beds, the growth rates of the coralline algae Neogoniolithon sp. and Amphiroa sp. were high at 9.5 mm and 15.5 mm per growth tip y−1, respectively. In a second experiment, we found lower mortality in coralline algae within a rhodolith bed compared to algae placed outside the bed, likely explained by the reduced resuspension that we found in a third experiment, and this positive feedback may explain the high population increase in the rhodoliths, once established when the turtles grazed down the seagrass canopy. Therefore, the grazing-protection mutualism between seagrasses and coralline algae is thus conditional and came into existence under a co-occurrence of intensive grazing pressure and rapid population growth of coralline algae facilitated by positive feedback from increased growth and reduced sediment resuspension by the dense rhodolith bed.
{"title":"Coralline Algal Population Explosion in an Overgrazed Seagrass Meadow: Conditional Outcomes of Intraspecific and Interspecific Interactions","authors":"Isis Gabriela Martínez López, Luuk Leemans, Marieke M. van Katwijk, S. Valery Ávila-Mosqueda, Brigitta I. van Tussenbroek","doi":"10.1007/s10021-024-00909-w","DOIUrl":"https://doi.org/10.1007/s10021-024-00909-w","url":null,"abstract":"<p>Interactions such as mutualism and facilitation are common in ecosystems established by foundation species; however, their outcomes vary and show conditionality. In a Mexican Caribbean Bay, a seagrass-coralline algae (rhodoliths) mutualism protects the seagrass <i>Thalassia testudinum</i> from green turtle overgrazing. We postulate that the state of the seagrass meadow in this bay depends on the strengths of the interactions among seagrasses, green turtles, and coralline algae. Spatio-temporal changes through satellite imagery showed rhodolith bed developed rapidly from 2009 (undetected) to 2016 (bed of 6934 m<sup>2</sup>). Typically, such rapid expansion of the rhodoliths does not occur in seagrass meadows. An in situ growth experiment of coralline algae showed that a combination of reduction in light and wave movement (usual in dense seagrass meadows) significantly reduced their growth rates. In the rhodolith beds, the growth rates of the coralline algae <i>Neogoniolithon</i> sp. and <i>Amphiroa</i> sp. were high at 9.5 mm and 15.5 mm per growth tip y<sup>−1</sup>, respectively. In a second experiment, we found lower mortality in coralline algae within a rhodolith bed compared to algae placed outside the bed, likely explained by the reduced resuspension that we found in a third experiment, and this positive feedback may explain the high population increase in the rhodoliths, once established when the turtles grazed down the seagrass canopy. Therefore, the grazing-protection mutualism between seagrasses and coralline algae is thus conditional and came into existence under a co-occurrence of intensive grazing pressure and rapid population growth of coralline algae facilitated by positive feedback from increased growth and reduced sediment resuspension by the dense rhodolith bed.</p>","PeriodicalId":11406,"journal":{"name":"Ecosystems","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140927183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}