Environmental-related variation of stoichiometric traits in body and organs of non-native sailfin catfishes Pterygoplichthys spp.

<p><span>Intraspecific variation in stoichiometric traits was </span><span>thought to be</span><span> an adaptive response to reduce the elemental imbalance between organisms and diet in the habitat. Studying the spatial variation of stoichiometric traits of non-native species and the factors </span><span>contributing</span><span> to the variation could help to better understand the invasion mechanism of non-native fish. </span></p> <p><span>In this study, stoichiometric traits (i.e. carbon [C], phosphorus [P], calcium [Ca] and their ratios) variation in the body and organs of non-native sailfin catfishes <em>Pterygoplichthys</em> spp. were investigated across 13 river sections in the main river basins of south China. The relationships between environmental factors and stoichiometric traits were analyzed using a general linear model and an information-theoretic approach. </span><span>A manipulated feeding experiment was conducted to investigate the impact of food quality on the stoichiometry of sailfin catfishes in a greenhouse.</span></p> <p><span>Sailfin catfishes exhibited considerable variability in body and organ elemental composition. Site identity was the main factor contributing to the variation</span><span>, which could be explained </span><span>by a combination of environmental factors</span><span> including climate, diet quality, fish species richness, and trophic status in the invaded rivers.</span> <span>Water chemistry (i.e. total nitrogen and phosphorus, ammonia nitrogen, and soluble reactive phosphorus) contributed to the most variation of stoichiometric traits. </span><span>Imbalances of P and Ca</span><span> between sailfin catfishes and food resources</span><span> varied among sampling sites, </span><span>reflecting </span><span>the spatial heterogeneity of nutrient limitation.</span><span> Juvenile sailfin catfishes exhibited stoichiometric homeostasis (0&lt;1/H&lt;0.25) for all elemental contents and ratios in the </span><span>feeding experiment.</span></p> <p><span>These findings suggested variation in stoichiometric traits of sailfin catfishes might be attributed to the changes in elemental metabolism to cope with context-specific environments. </span><span>This study provided heuristic knowledge about environmental-related variation in stoichiometric traits, which could enhance the understanding of the non-native species' adaptation to resource fluctuation in the invaded ecosystems. </span></p>