Modeling food web structure and selenium biomagnification in lake macquarie, New South Wales, Australia, using stable carbon and nitrogen isotopes

Abstract

As a consequence of coal-fired power station operations, elevated selenium concentrations have been reported in the sediments and biota of Lake Macquarie (New South Wales, Australia). In the present study, an ecosystem-scale model has been applied to determine how selenium in a seagrass food web is processed from sediments and water through diet to predators, using stable isotopes (δ(13) C and δ(15) N) to establish the trophic position of organisms. Trophic position, habitat, and feeding zone were examined as possible factors influencing selenium bioaccumulation. Selenium concentrations ranged from 0.2 μg/g dry weight in macroalgae species to 12.9 μg/g in the carnivorous fish Gerres subfasciatus. A mean magnification factor of 1.39 per trophic level showed that selenium is biomagnifying in the seagrass food web. Habitat and feeding zone influenced selenium concentrations in invertebrates, whereas feeding zone was the only significant factor influencing selenium concentrations in fish. The sediment-water partitioning coefficient (Kd ) of 4180 showed that partitioning of selenium entering the lake to particulate organic material (POM) is occurring, and consequently availability to food webs from POM is high. Trophic transfer factors (invertebrate = 1.9; fish = 1.2) were similar to those reported for other water bodies, showing that input source is not the main determinant of the magnitude of selenium bioaccumulation in a food web, but rather the initial partitioning of selenium into bioavailable POM. Environ Toxicol Chem 2015;34:608-617. © 2014 SETAC.

Widespread variation in stable isotope trophic position estimates: patterns, causes, and potential consequences

“…2013, Schneider et al. 2015, Azevedo‐Silva et al. 2016), to determine the effects of humans on ecosystem health (Mavraki et al.…”

Drivers of biomagnification of Hg, As and Se in aquatic food webs: A review

“…Despite being an essential element excess concentration can cause adverse effects on biota (Jasonsmith et al, 2008;Savery et al, 2013). In the aquatic environment Se is introduced by plankton in particulate form, and therefore it is incorporated into organic matter and transferred from invertebrates to fish (Schneider et al, 2015). Globally, there is a growing interest in elucidating the results of Se and Hg interaction in aquatic ecosystems, as Se has been reported to exert a reducing effect against MeHg toxicity (Azad et al, 2019;Bjerregaard & Christensen, 2012;Burger et al, 2013b;Burger & Gochfeld, 2013a).…”

“…In relation to factors influencing biomagnification, trophic structure and diet have been reported to be key factors that help to understand trophodynamics, accumulation and biomagnification along food webs (Arcagni et al, 2013;Schneider et al, 2015). Studies have indicated that in networks composed of plankton, algae, invertebrates, macrophytes and fish, Se only biomagnifies in fish and its biomagnification potential could be related to the complexity of the food web (Arcagni et al, 2013;Jasonsmith et al, 2008;Mann et al, 2011;Økelsrud et al, 2016).…”

“…Studies have indicated that in networks composed of plankton, algae, invertebrates, macrophytes and fish, Se only biomagnifies in fish and its biomagnification potential could be related to the complexity of the food web (Arcagni et al, 2013;Jasonsmith et al, 2008;Mann et al, 2011;Økelsrud et al, 2016). However, it has been expected that biomagnifying potential is more evident in freshwater lakes and depends on the species chemistry (Arcagni et al, 2013;Dang and Wang, 2011;Jardine et al, 2006;Schneider et al, 2015). For example, in complex food webs (plankton, macroalgae, benthic microalgae, invertebrates, detritus, seagrasses, epiphytes and fish) from Lake Macquarie (New South Wales, Australia), Se concentrations ranged from 0.2 μg g -1 (macroalgae) to 12.9 μg g -1 in predatory fish and a mean magnification factor of 1.39 per trophic level, indicating a significant biomagnification.…”

“…For example, in complex food webs (plankton, macroalgae, benthic microalgae, invertebrates, detritus, seagrasses, epiphytes and fish) from Lake Macquarie (New South Wales, Australia), Se concentrations ranged from 0.2 μg g -1 (macroalgae) to 12.9 μg g -1 in predatory fish and a mean magnification factor of 1.39 per trophic level, indicating a significant biomagnification. Feeding site in conjunction with habitat were the factors that may explain the magnification (Schneider et al, 2015).…”