Abstract
High trophic plasticity is often invoked to explain the successful expansion of many aquatic species. Bombay duck (BD) outcompete other traditionally commercial fishes in the East China Sea (ECS) in recent years, displaying a continuous and sharp increase of catches, however, little is known whether the competition advantage of BD was related to its trophic plasticity. Using stable isotope analysis (SIA), we investigated the trophic ecology of BD in the south-central ECS in two periods. Significant differences in δ13C and δ15N values were found between sampling months and among body sizes. Modal (95% credibility limits) estimation showed that BD’s trophic position (TP) gradually increased from 3.56 (3.31–3.82) in G1 (120–150 mm for body size) to 4.09 (3.69–4.50) in G5 (241–270 mm) in November, and from 3.37 (2.92–3.88) in G2 (151–180 mm) to 3.66 (3.07–4.23) in G4 (211–240 mm) in April, respectively, suggesting obvious ontogenetic variation of δ15N and TP. More importantly, the TP of BD within the same body size showed wide amplitude, indicating BD possess high trophic plasticity, and can capture prey from low to high trophic levels. Further quantitative analysis based on the MixSIAR model showed that BD mainly fed on zooplankton and fish, but its feeding habit was characterized by the consumption of gradually reduced zooplankton and increased fish associated with increased body size. Interestingly, the fish’s contribution to BD showed obvious seasonal variation. It can be explained by varied food availability in ECS. Relatively low fish prey in April forced BD to adjust its diet, adding the ingestion of shrimps and cephalopods corresponding to temporal variations in food availability. The present study provides the evidence that high trophic plasticity exists in the feeding strategy of BD, which is reflected in the ability to adjust the feeding preference according to nutritional needs and food environmental changes; thus, it is competitively advantageous and may partly explain why BD is becoming the predominant species and displays an extensive distribution in the ECS.
Highlights
Trophic plasticity is the adaptation of organisms to minimize potential competition for food by shifting their diets (MacNeil et al, 1997; Lefebvre et al, 2009; Mavraki et al, 2020)
It has been proven that the stable isotope composition varies in consumers living in contrasting environments, such as L. polyactis living in near-shore and offshore waters or the macrozoobenthos and fishes living in lagoons in different seasons due to different compositions of organic matter sources (Ji et al, 2011a; Zheng et al, 2020)
In inshore areas susceptible to runoff, the mixing of terrestrial and marine-originated carbon might result in variations in δ13C inshore and offshore, while δ15N may be affected by enrichment in the ocean or proximity to nitrogen land sources (Sherwood and Rose, 2005)
Summary
Trophic plasticity is the adaptation of organisms to minimize potential competition for food by (partly) shifting their diets (MacNeil et al, 1997; Lefebvre et al, 2009; Mavraki et al, 2020). It is a form of trophic generalism, implying that a species is capable of feeding on a broad food spectrum, but only exploit a part depending on the competitive environment in which it occurs (Gutt, 2006; Riera, 2009, 2010) Species could adapt their foraging strategy in relation to variation of the availability of their trophic subsidies (Kopp et al, 2015; Timmerman et al, 2021) and the spatial-temporal variation in the food availability may greatly affect the food ingested and diet breadth, making species exhibit a trophic plasticity (Adite et al, 2013). It is important to well document the diet spectrum variation and the trophic plasticity to explore the species feeding strategies, would give a better insight into the trophic structure dynamic, an important tool and baseline information to conserve, manage and restore fish resources in their habitat (Adite et al, 2013; García-Rodríguez et al, 2021)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
