Trophic segregation of a fish assemblage along lateral depth gradients in a subtropical coastal lagoon revealed by stable isotope analyses

Mont’Alverne, Renata; Pereyra, Paula Evelyn Rubira; Garcia, Alexandre

doi:10.1111/jfb.12903

Cited by 25 publications

(8 citation statements)

References 70 publications

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“…Therefore, in addition to median values, the mean values of diet proportions were considered to describe the trophic contributions of individual sources to particular groups of consumers (Figure 7). The dominance of phytoplankton-driven OM to fish food webs in our study were clearly different from other studies in nearshore and coastal areas (Connolly et al, 2009;de Lecea et al, 2016;McMahon et al, 2021), but was similar to coastal lagoon food webs (Mont'Alverne et al, 2016) and offshore food webs of Daya Bay (Ying et al, 2020). The low phytoplankton contribution to other temperate food webs were mostly associated with low phytoplankton production due to high turbidity despite nutrient availability (Hoffman et al, 2008;Shang et al, 2008).…”

Section: Contribution Of Organic Matter Sources To Fish Food Webscontrasting

confidence: 87%

Phytoplankton Fuel Fish Food Webs in a Low-Turbidity Temperate Coastal Embayment: A Stable Isotope Approach

Kundu

Kim

et al. 2021

Front. Mar. Sci.

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Trophic contributions of diverse OM sources to estuarine and coastal food webs differ substantially across systems around the world, particularly for nekton (fish, cephalopods, and crustaceans), which utilize basal resources from multiple sources over space and time because of their mobility and feeding behaviors at multiple trophic levels. We investigated the contributions of putative OM sources to fish food webs and assessed the spatiotemporal patterns, structures, and trophic connectivity in fish food webs across four seasons from three closely spaced (10–15 km) sites: an estuarine channel (EC), a deep bay (DB), and an offshore (OS) region in Gwangyang Bay, a high-productivity, low-turbidity estuarine embayment off the Republic of Korea. While nearly all previous studies have focused on few representative species, we examined δ13C and δ15N values of whole nekton communities along with dominant benthic macro-invertebrates, zooplankton, and their putative primary food sources. The δ13C and δ15N values coupled with MixSIAR, a Bayesian mixing model, revealed that these communities utilized multiple primary producers, but phytoplankton comprised the primary trophic contributor (46.6–69.1%). Microphytobenthos (15.8–20.4%) and the seagrass Zostera marina (8.6–19.8%) made substantial contributions, but the role of river-borne terrestrial organic matter was negligible. Spatially different species composition and stable isotope values, but higher utilization of coastal phytoplankton by estuarine fish, indicated disparate food webs structures between the EC and DB/OS coastal areas, with considerable trophic connectivity. Greater overlaps in fish and cephalopod isotopic niches than among other consumers and a higher estimated carbon trophic enrichment factor for EC nekton confirmed feeding migration-mediated biological transport of coastal OM sources to the estuary. Further, the seasonally consistent structures and resource utilization patterns indicate that fish food webs are resilient to changes at lower trophic levels. Our results contrast with those for other highly turbid coastal systems depending highly on diversified basal sources, including exported terrestrial and wetland detritus alongside autochthonous phytoplankton. Finally, this study provides a novel perspective on the role of OM sources in such low turbidity and highly productive coastal embayments and enhances our understanding of marine ecosystems.

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Section: Contribution Of Organic Matter Sources To Fish Food Webscontrasting

confidence: 87%

Phytoplankton Fuel Fish Food Webs in a Low-Turbidity Temperate Coastal Embayment: A Stable Isotope Approach

Kundu

Kim

et al. 2021

Front. Mar. Sci.

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“…characin Astyanax eigenmanniorum (Cope 1894)], which derive their energy from food sources available at the upper reaches of the lagoon, are transported into the estuary by episodes of high freshwater discharge (Garcia et al ., , ). On the other hand, food web characterization of littoral (<2 m) and deeper habitats (3–6 m) of Patos Lagoon, based on stable isotopes and stomach contents, suggested restricted connectivity along the depth profile (Mont'Alvernne et al ., ). In this regard, the longitudinal carbon exchanges mediated by fishes moving up and down the salinity gradient of the Patos Lagoon may be more prevalent than trophic exchanges occurring at smaller scales, such as the one between shallow and deeper habitats (Fig.…”

Section: Fish Diversity Distribution and Ecological Connectionsmentioning

confidence: 97%

Aspects of fish conservation in the upper Patos Lagoon basin

Fontoura

Vieira

Becker

et al. 2016

Journal of Fish Biology

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The Patos Lagoon basin is a large (201 626 km(2) ) and complex drainage system in southern Brazil. The lagoon is 250 km long and 60 km wide, covering an area of 10 360 km(2) . The exchange of water with the Atlantic Ocean occurs through a 0·8 km wide and 15 m deep inlet, fixed by 4 km long jetties, at the southernmost part of the Patos Lagoon. The estuarine area is restricted to its southern portion (10%), although the upper limit of saline waters migrates seasonally and year to year, influenced by the wind regime and river discharge. The known number of recorded limnetic fish species is 200, but this number is expected to increase. A higher endemism is observed in fish species occurring in upper tributaries. The basin suffers from the direct impact of almost 7 million inhabitants, concentrated in small to large cities, most with untreated domestic effluents. There are at least 16 non-native species recorded in natural habitats of the Patos Lagoon basin, about half of these being from other South American river basins. Concerning the fishery, although sport and commercial fisheries are widespread throughout the Patos Lagoon basin, the lagoon itself and the estuarine area are the main fishing areas. Landing statistics are not available on a regular basis or for the whole basin. The fishery in the northern Patos Lagoon captures 31 different species, nine of which are responsible for most of the commercial catches, but only three species are actually sustaining the artisanal fishery: the viola Loricariichthys anus: 455 kg per 10 000 m(2) gillnet per day, the mullet Mugil liza: 123 kg per 10 000 m(2) gillnet per day and the marine catfish Genidens barbus: 50 kg per 10 000 m(2) gillnet per day. A decline of the fish stocks can be attributed to inadequate fishery surveillance, which leads to overfishing and mortality of juveniles, or to decreasing water quality because of urban and industrial activities and power production. Global climatic changes also represent a major threat to the Patos system by changing the frequency of El Niño-La Niña-Southern Oscillation (ENSO).

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“…The advection of drift biomass from shallow areas may fuel deep secondary production through substantial fluxes of energy and nutrients to recipient communities, creating spatially subsidized food webs (Britton-Simmons et al 2012, Hyndes et al 2014). However, low contributions of drift macroalgae to herbivores and detritivores occurring in deeper areas have been reported in the PLE (Mont' Alverne et al 2016). Thus, according to the hydrological (Britton-Simmons et al 2009) and basin-shape conditions (Britton-Simmons et al 2012, Filbee-Dexter & Scheibling 2016, much of the biomass advected to deep channels can be exported to adjacent coastal areas, hence representing nutrient loss from the system (Martins et al 2007).…”

Section: Contribution Of Drift Macroalgae To Sediment C and Nmentioning

confidence: 99%

“…Nonetheless, bloom-forming macroalgae do not contribute significantly to the diets of herbivorous fish in the PLE (Mont'Alverne et al 2016, Garcia et al 2017. As in many temperate estuaries, the PLE harbours few species of herbivorous fish and crustaceans (Mont'Alverne et al 2016), and herbivory therefore cannot control macroalgal blooms. Furthermore, top-down controls on algal blooms can be limited under nutrient-enriched conditions, such as in the PLE (e.g Martinetto et al 2011)…”

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confidence: 99%

Dynamics of estuarine drift macroalgae: growth cycles and contributions to sediments in shallow areas

Lanari¹,

Kennedy²,

Copertino³

et al. 2017

Mar. Ecol. Prog. Ser.

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Blooms of opportunistic macroalgae play a major role in nutrient cycling in shallow coastal areas. However, their short life cycles and rapid biomass remineralization can promote feedbacks on sediment nutrient recycling, leading to self-regenerated blooms and the consequent disruption of local biogeochemical cycles. We investigated the potential for algal biomass-sediment nutrient feedbacks in shallow estuarine areas under natural scenarios of biomass accumulation. To do so, the environmental factors driving the dynamics of drift macroalgal blooms and their biomass contributions to sedimentary organic matter were assessed in a 2 yr field survey in shallow bays of the Patos Lagoon estuary, southern Brazil.Interactive effects of hydrological and water physico-chemical parameters modulated the abundance and persistence of algal biomass. The magnitude of the bloom biomass among bays was positively correlated to wind exposure, reflecting the importance of drifting mat advection by onshore wind-driven waves and currents on biomass accumulation. Large biomass accumulations represented a substantial nutrient stock within the system. However, no significant increases in the sediment total organic carbon or total nitrogen were observed.Isotopic analysis revealed overall low contributions of macroalgal biomass to the sedimentary organic matter during senescence, highlighting possible dual effects of wind exposure on biomass accumulation and deposition. Our findings suggest that, in highly hydrodynamic systems, feedbacks between biomass accumulation and sediment nutrient regeneration are unlikely to occur. Given the unknown fate of algal-bound nutrients, more studies are necessary to determine the effects of drift macroalgae-dominated phases on the long-term balance of nutrients within the estuarine system. KEY WORDS: Macroalgal blooms  Hydrology  Wind exposure  Sedimentary organic matter  Fate of nutrients  Patos Lagoon Information regarding local freshwater discharge was provided by the Brazilian National Water Agency (www.hidroweb.ana.gov.br). The sum of the flow of the 3 main rivers was assumed to be a proxy for the total Patos Lagoon freshwater discharge (Möller et al. 2001).Data on hourly wind speed and direction, obtained at the mouth of the PLE, were provided by the Rio Grande Maritime Pilotage (www.rgpilots.com.br/). Water physico-chemical parametersThe estuarine water level (fixed ruler) in relation to the mean water level of the lagoon (40 cm) was obtained daily in an area approximately 3 km from the studied sites within the Brazilian Long-Term Ecological Research Program (www.peld.furg.br/index.php/metadados).

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Trophic segregation of a fish assemblage along lateral depth gradients in a subtropical coastal lagoon revealed by stable isotope analyses

Cited by 25 publications

References 70 publications

Phytoplankton Fuel Fish Food Webs in a Low-Turbidity Temperate Coastal Embayment: A Stable Isotope Approach

Phytoplankton Fuel Fish Food Webs in a Low-Turbidity Temperate Coastal Embayment: A Stable Isotope Approach

Aspects of fish conservation in the upper Patos Lagoon basin

Dynamics of estuarine drift macroalgae: growth cycles and contributions to sediments in shallow areas

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