Seasonal fluctuation in food sources of herbivorous gastropods in a subtropical seagrass bed estimated by stable isotope analysis

Nakamoto, Kenta; Kawamura, Tomohiko; Ohtsuchi, Naoya; Yamada, Hideaki; Kitagawa, Takashi; Watanabe, Yoshirô

doi:10.1017/s0025315418001108

Cited by 13 publications

(8 citation statements)

References 44 publications

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“…However, the nutrient content, cellulose shoot, and palatability of seagrasses are distinctly different from those of most macroalgae. Similar to our findings of the seagrass beds around Dongsha Island, stable isotope analysis also showed that macroalgae were generally the main food sources of herbivores in other tropical seagrass ecosystems [58][59][60]. For better resolution of production, consumption, and energy flows, we suggest distinguishing seagrasses and macroalgae as different compartments of primary producers when constructing trophic models of seagrass beds.…”

Section: Discussionsupporting

confidence: 86%

Highly Productive Tropical Seagrass Beds Support Diverse Consumers and a Large Organic Carbon Pool in the Sediments

et al. 2021

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Tropical seagrass beds are productive coastal ecosystems that are important blue carbon sinks and crucial habitats and feeding grounds for consumers at high trophic levels. To understand how energy sustains the ecosystem from seagrass production, we constructed an Ecopath trophic model to reveal the possible pathways of energy flow in the tropical seagrass beds around Dongsha Island, South China Sea. The model indicates that Dongsha seagrass beds were developing but well-structured ecosystems. The productive seagrasses were rarely directly consumed by herbivores and, ultimately, flowed into detrital pools. Detritus was the main food source used to support diverse consumers in the food web. Nevertheless, the low cycling rate (2.74%) suggests that most detritus was not reused or exported and was stored as a large organic carbon pool in the sediments. The detritus-feeding invertebrates are keystone groups in the Dongsha seagrass beds, as they recycle energy from detritus and transfer to top predators such as sharks. The predation of top predators affected the biomasses of other compartments, leading to strong top-down control via a trophic cascade effect.

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Section: Discussionsupporting

confidence: 86%

Highly Productive Tropical Seagrass Beds Support Diverse Consumers and a Large Organic Carbon Pool in the Sediments

et al. 2021

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“…Similarly, substantial temporal variation in the stable isotopes of POM and macroalgae was also found in Zostera marina and Cymodocea nodosa seagrass meadows (Vizzini and Mazzola, 2003;Mittermayr et al, 2014), respectively. Such seasonal variations may be attributed to environmental factors and/or biotic physiological processes (Mittermayr et al, 2014;Jankowska et al, 2019;Nakamoto et al, 2019).…”

Section: Isotope Ratios Characteristics Of Food Sourcesmentioning

confidence: 99%

“…It is possible, because the absolute decomposition of seagrass dead leaves takes longer compared with macroalgae (Lavery et al, 2013;Liu et al, 2016b;Trevathan-Tackett et al, 2020), which might accumulate adequate food for the diet of detritivores. Meanwhile, seagrass meadows in tropical regions may accumulate more seagrass debris than those in temperate regions as a result of relatively mild seasonal changes (Nakamoto et al, 2019). Therefore, adequate seagrass detritus throughout the year in tropical seagrass meadows might keep the transfer pathway of carbon derived from seagrass stable along the detritus food chain (Figure 5).…”

Section: Flow Of Seagrass Carbon In Food Web and Its Influencing Factorsmentioning

confidence: 99%

“…Seagrass is generally considered to have poor nutrition and low palatability for herbivores (Vergés et al, 2011;Boudouresque et al, 2016). Therefore, it is generally considered to be rarely ingested by herbivores (Nakamoto et al, 2019). However, mild seasonal variations in tropical seagrass meadows generally allow seagrass to remain abundant throughout the year (Nakamoto et al, 2019), which may increase the likelihood and intensity of seagrass consumption by herbivores (Heck et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Carbon Transfer Processes of Food Web and Trophic Pathways in a Tropical Eutrophic Seagrass Meadow

et al. 2021

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Seagrass meadows provide important habitats and rich organic carbon sources for consumers at different trophic levels but are threatened by accelerating eutrophication in coastal waters. Nevertheless, at present, carbon transfer processes throughout the food web and trophic pathways in eutrophic seagrass meadows are still poorly known. To resolve this issue, carbon sources of different trophic communities in a eutrophic tropical seagrass meadow [Xincun (XC) bay, South China Sea] under eutrophication were examined in summer and winter using dual stable isotopes. The δ13C value of omnivores and carnivores overlapped more with that of herbivores and planktivores/filter feeders, which mainly overlapped with that of epiphytes in summer and macroalgae in winter. Meanwhile, epiphytes and macroalgae exhibited high biomass and corresponding highest contribution to herbivores, omnivores, and carnivores in summer and winter, respectively. These results suggest that the grazing food chain was the main trophic pathway in this eutrophic seagrass meadow, and that the transfer of carbon flow in the grazing food chain was mainly dominated by the proliferating epiphytes or macroalgae carbon. In contrast, the contribution of seagrass to detritivores in both seasons was higher than that of other food sources. Our findings suggest that in eutrophic tropical seagrass meadows, the proliferation of epiphytes or macroalgae induced by high nutrient loading, as well as their seasonal changes, has a greater impact on the transfer of carbon in the grazing food chain than that in the detritus food chain, and the seagrass fueled the food web mainly through the detritus food chain.

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“…They not only provide a nursery ground, habitat, shelter, and grazing areas for a large quantity of fish and invertebrates (Heck et al 2003, Unsworth et al 2019) but also provide rich organic carbon sources to support their food webs (Jinks et al 2019, Jänes et al 2020a, b, Jiang et al 2020). These organic carbon sources are usually very diverse, mainly including dead and living seagrass vegetation, epiphytes, macroalgae, particulate organic matter (POM, including phytoplankton), and microphytobenthos in the sediment (Smit et al 2005, 2006, Baeta et al 2009, Nakamoto et al 2019. The flow of organic carbon is mainly through grazing and detritus food chains (Patricio and Marques 2006).…”

Section: Introductionmentioning

confidence: 99%

Eutrophication reduces seagrass contribution to coastal food webs

et al. 2021

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Food sources and food web structure in seagrass meadows are important determinants of ecosystem functions and services. However, there is little information on the effect of eutrophication on food source contributions and food web structure in seagrass meadows. Here we used stable isotopes of carbon and nitrogen (δ 13 C and δ 15 N) to investigate how do different levels of nutrient enrichment affect the diets of consumers and food web structure within tropical seagrass meadows. We found that the diet contributions of macroalgae (mean 24% AE 12% for fish, 21% AE 5% for invertebrates), particulate organic matter (mean 19% AE 12% for fish, 18% AE 8% for invertebrates), and sediment organic matter (mean 24% AE 13% for fish, 21% AE 8% for invertebrates) to fish and invertebrates were all higher in seagrass meadows with higher nutrient concentrations, while seagrass and epiphytes contributed more to consumers in seagrass meadows with lower nutrient concentrations. Meanwhile, higher nutrient concentrations decreased the trophic position (mean 2.6 AE 0.5 in high-nutrient level, 3.4 AE 0.6 in low-nutrients level) of consumers and food chain length (2.5 in high-nutrient level, 2.9 in lownutrients level). Higher nutrient concentrations reduced the contribution of seagrass carbon to consumers through the grazing food chain, but enhanced the flow of macroalgal carbon to consumers through the grazing food chain. Overall, eutrophication modified the food web structure of seagrass meadows. We recommend that measures be taken to decrease nutrient input into seagrass ecosystems to maintain its important functions and services.

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Seasonal fluctuation in food sources of herbivorous gastropods in a subtropical seagrass bed estimated by stable isotope analysis

Cited by 13 publications

References 44 publications

Highly Productive Tropical Seagrass Beds Support Diverse Consumers and a Large Organic Carbon Pool in the Sediments

Highly Productive Tropical Seagrass Beds Support Diverse Consumers and a Large Organic Carbon Pool in the Sediments

Carbon Transfer Processes of Food Web and Trophic Pathways in a Tropical Eutrophic Seagrass Meadow

Eutrophication reduces seagrass contribution to coastal food webs

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