Eutrophication reduces seagrass contribution to coastal food webs

Cui, Lijun; Jiang, Zhijian; Huang, Xiaoping; Chen, Qiming; Wu, Yunchao; Liu, Songlin; Li, Jinlong; Macreadie, Peter I.

doi:10.1002/ecs2.3626

Cited by 11 publications

(4 citation statements)

References 57 publications

(63 reference statements)

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“…Likewise, calcareous epiphytes contribute to this trend, notably in Lendra (Figure 8C). In seagrass meadows enriched with substantial nutrient concentrations, the presence of green and red algae predominates, whereas seagrass beds characterized by lower nutrient levels are predominantly populated by brown algae, such as Padina pavonica [78]. This investigation reveals that both Mangrove Inn and Lendra have elevated nutrient levels (measuring 0.78 and 0.85 mg L −1 , respectively), where green calcareous epiphytes are prevalent.…”

Section: Calcareous Epiphytesmentioning

confidence: 76%

Seagrass Blue Carbon Stock and Air–Sea CO2 Fluxes in the Karimunjawa Islands, Indonesia during Southeast Monsoon Season

Latifah,

Ningsih,

Kartadikaria

et al. 2023

Diversity

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Research focusing on seagrass ecosystems as carbon storage has been conducted in various Indonesian waters. However, an essential aspect that remains unexplored is the simultaneous analysis of blue carbon storage in seagrass alongside carbon dioxide (CO2) flux values, particularly within Karimunjawa waters. This study aims to assess the organic carbon stock and sea–air CO2 flux in seagrass ecosystems in Karimunjawa. Our hypothesis posits that although seagrass ecosystems release CO2 into the water, their role as blue carbon ecosystems enables them to absorb and accumulate organic carbon within seagrass biomass and sediments. This investigation took place in Karimunjawa waters, encompassing both vegetated (seagrass meadows) and unvegetated (non-seagrass meadows) areas during August 2019, 2020, and 2022. Over this period, the organic carbon stock in seagrass and sediment displayed an increase, rising from 28.90 to 35.70 gCorg m−2 in 2019 and from 37.80 to 45.25 gCorg m−2 in 2022. Notably, the expanse of seagrass meadows in Karimunjawa dwindled by 328.33 ha from 2019 to 2022, resulting in a total carbon stock reduction of the seagrass meadows of 452.39 tC to 218.78 tC. Sediment emerges as a pivotal element in the storage of blue carbon in seagrass, with sedimentary organic carbon outweighing seagrass biomass in storage capacity. The conditions in Karimunjawa, including a high A:B ratio, low dry bulk density, and elevated water content, foster a favorable environment for sediment carbon absorption and storage, facilitated by the waters’ CO2 emission during the southeast monsoon season. Notably, our findings reveal that CO2 release within vegetated areas is lower compared to unvegetated areas. This outcome underscores how seagrass ecosystems can mitigate CO2 release through their adeptness at storing organic carbon within biomass and sediment. However, the presence of inorganic carbon in the form of calcium carbonate introduces a nuanced dynamic. This external source, stemming from allochthonous origins like mangroves, brown algae like Padina pavonica, and calcareous epiphytes, leads to an increase in sedimentary organic carbon stock of 53.2 ± 6.82 gCorg m−2. Moreover, it triggers the release of CO2 into the atmosphere, quantified at 83.4 ± 18.26 mmol CO2 m−2 d−1.

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Section: Calcareous Epiphytesmentioning

confidence: 76%

Seagrass Blue Carbon Stock and Air–Sea CO2 Fluxes in the Karimunjawa Islands, Indonesia during Southeast Monsoon Season

Latifah,

Ningsih,

Kartadikaria

et al. 2023

Diversity

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“…The biogeochemical processes within the interior of the saltwater wedge, including those that host mixed‐convective processes such as demonstrated here, is a topic worthy of further research effort (Heiss et al., 2017; Kim et al., 2020; Robinson et al., 2009). This research should consider the mixed saltwater influx‐efflux patterns that are expected in the near‐shore aquifer, given the dependency of seafloor ecosystems on nutrient loads (e.g., Cui et al., 2021; Lee et al., 2007).…”

Section: Discussionmentioning

confidence: 99%

Flow and Transport in Coastal Aquifer‐Aquitard Systems: Experimental and Numerical Analysis

Zhang,

Lu,

Shen

et al. 2024

Water Resources Research

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Coastal aquifers are commonly layered, and thus, a clear understanding of groundwater flow and salt transport in layered coastal aquifers is important for managing fresh groundwater. However, the influence of leakage between adjacent aquifers on flow and transport processes remains largely unknown where the influence of tides is considered. This study used laboratory experiments and numerical simulation to examine the processes of flow and transport within a tidal aquifer‐aquitard system (i.e., an unconfined aquifer underlain by a semi‐confined aquifer, with an intervening thin aquitard). The laboratory‐scale observations of the current study are the first observations of offshore fresh groundwater within a semi‐confined coastal aquifer. The numerical and laboratory results are in close agreement, revealing that upward leakage from the semi‐confined aquifer into the saltwater wedge of the overlying unconfined aquifer caused buoyant instabilities to form. The development of freshwater fingers created complex saltwater‐freshwater mixing, leading to mixed saltwater influx‐efflux patterns across the sloping aquifer‐ocean interface. Compared with non‐tidal conditions, tidal forces reduced the net upward leakage from the semi‐confined aquifer to the overlying unconfined aquifer. This increased the horizontal flow toward the sea, which in turn reduced the extent of the saltwater wedge in the semi‐confined aquifer. The higher rates of both fresh and saline submarine groundwater discharge (SGD), caused by tides, led to lower groundwater ages in the semi‐confined aquifer. These findings have important implications for unveiling the complex characteristics of seawater intrusion, SGD and geochemical hotspots within layered coastal aquifers.

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“…They are not only highly productive ecosystems, but also support food webs of coastal habitats (Jiang et al, 2019;Unsworth et al, 2019;Canadell and Jackson, 2021). They provide various food sources including seagrass, epiphytes, macroalgae, suspended particulate organic matter (SPOM), and microphytobenthos in the sediment for various fish and invertebrates, and serve as a shelter, habitat, and nursery ground for adult and juvenile faunas (Liu et al, 2020b;Cui et al, 2021a). However, understanding the function of seagrass bed food webs remains to be a challenge since it requires an effective approach to discriminate the food sources and their potential importance in seagrass beds (Abrantes and Sheaves, 2009;Kohlbach et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…However, this approach only provides two-dimensional discrimination, which may fail to identify the trophic base of the seagrass bed food webs, especially for tropical seagrass bed food webs, since they usually have more diversified primary producers and the isotopic values of food sources are often similar (Nakamoto et al, 2019). For example, in tropical seagrass ecosystems, the isotopic values of seagrass are usually close to those of epiphytes (Mittermayr et al, 2014;Cui et al, 2021a). In addition, the temporal variances in environmental factors may also result in similar stable isotopic values between seagrass and other food sources (Fritts et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Identification of food sources in tropical seagrass bed food web using triple stable isotopes and fatty acid signatures

et al. 2023

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Identifying the trophic role of primary producers is the basis of assessing seagrass bed functions but remains difficult due to the underdetermined analysis method. Here, we analyzed the multiple isotopes (δ13C, δ15N, and δ34S values) and fatty acid markers of food sources and macrobenthos in a tropical seagrass bed in summer and winter, and tried to combine these indicators to resolve the limitation of δ13C and δ15N values analysis. We found that the δ13C and δ15N values of epiphytes were like that of seagrass and macroalgae, while the δ34S values of epiphytes and macroalgae were significantly different, and the dominant unsaturated Fatty acid markers of seagrass (18:2n6c and 18:3n3) and epiphytes (16:1n7) were obviously different. These results suggest that the combination of multiple isotopes and Fatty acid markers can effectively distinguish the complex food source. In addition, we also found that multiple isotopes were more suitable to identify the food sources of polychaetes and snails with simple diets, fatty acids were more suitable to identify the food sources of crustaceans with complex diets, but their combination is essential in identifying the diets of macrobenthos since the wide range of isotopic values for omnivores crustaceans and the Fatty acid markers transformation during snails and polychaetes assimilation might mislead us when only isotopes or Fatty acid markers were used. Our findings suggest that in tropical seagrass beds, using multiple isotopes and fatty acid markers together can help reduce the uncertainty caused by single markers variation and thus strengthen the separation of food sources and the diets of different consumer species.

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Eutrophication reduces seagrass contribution to coastal food webs

Cited by 11 publications

References 57 publications

Seagrass Blue Carbon Stock and Air–Sea CO2 Fluxes in the Karimunjawa Islands, Indonesia during Southeast Monsoon Season

Seagrass Blue Carbon Stock and Air–Sea CO2 Fluxes in the Karimunjawa Islands, Indonesia during Southeast Monsoon Season

Flow and Transport in Coastal Aquifer‐Aquitard Systems: Experimental and Numerical Analysis

Identification of food sources in tropical seagrass bed food web using triple stable isotopes and fatty acid signatures

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