The Effect of Different Habitat Types and Ontogenetic Stages on the Diet Shift of a Critically Endangered Fish Species, Coreius guichenoti (Sauvage and Dabry de Thiersant, 1874).

Zhi Yang,Fang Shi,Xiaojuan Chen,Jiangping Tao,Peng Zhang,Huiyuan Tang,Chengyan Wan,Na Zhao

doi:10.3390/ijerph15102240

Abstract

This study examined the effect of habitat types and ontogenetic stages on the diet shift of Coreius guichenoti (Sauvage and Dabry de Thiersant, 1874), a critically endangered fish species. Based on the stable isotope analysis method, the following was explored: the variations in δ13C and δ15N values, isotopic niche width and four basal food sources (Mollusks, Macrocrustaceans, Aquatic insect larvae and particulate organic matters (POMs)) among three essential habitat types (the spawning ground, natural riverine feeding and nursery area, and Three Gorges Reservoir area) and between two ontogenetic stages (immature and fully mature stages). A diet shift associated with habitat type changes was observed, but there were no obvious differences in diet composition between the two ontogenetic stages. Dietary plasticity and a preference for specific foods were the important determinants of feeding behavior through the life history of this species. POM was important for the survival of this species in the resource-limited spawning ground, but this species fed more heavily on higher-order consumers in resource-abundant areas. This study highlights the importance of maintaining free connectivity among different habitats (particularly spawning grounds) to ensure the long-term sustainability of potamodromous fish species as well as the full investigation of all types of critical habitats for understanding the trophic ecology of a single fish species.

Highlights

The identification and protection of fish critical habitats are central to the active management of species at risk [1,2]
This study of the diet shifts of a critically endangered fish species among three habitat types (SG, NRFA and TGRA) and between two ontogenetic stages (FMS and IS) showed that an obvious diet shift existed among three habitat types, but not between ontogenetic stages
Our results determined the food preference of Largemouth bronze gudgeon (LBG) and confirmed the serious intraspecific competition between immature and fully matured individuals in a resource-limited area, both of which can guide future work conducted in captive breeding of LBG

Summary

Introduction

The identification and protection of fish critical habitats are central to the active management of species at risk [1,2]. The spawning grounds and nursery, migration, and rearing areas on which fish species depend directly to complete their life history cycles, are identified as the critical habitats for fish species [1]. Many fish species use different critical habitats within different life history stages [3,4]. Due to environmental heterogeneity in different habitats, the fish species may exhibit plastic dietary patterns and diet shifts due to variation in the accessibility and availability of potential food sources [3,5,6]. Acquiring information on the diet shift among different habitats and

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