# Effects of Habitat Differences and Invasive Species Competition on Age and Growth of Triplophysa strauchii

## TL;DR

This study examines how habitat differences and invasive species affect the growth and lifespan of Triplophysa strauchii fish in different environments.

## Contribution

The study reveals distinct life-history strategies in geographically isolated populations of T. strauchii due to habitat and invasive species influences.

## Key findings

- Oxbow lake populations of T. strauchii show greater longevity and larger body sizes compared to stream populations.
- Stream populations experience body size miniaturization and reduced lifespan due to invasive species competition.
- Growth models indicate a fast-growth type with similar fitting results across Von Bertalanffy, Gompertz, and Logistic models.

## Abstract

Fish growth traits constitute key adaptive attributes to environmental conditions, with growth variation representing the most direct and common response to habitat challenges. Distinct aquatic environments shape divergent life-history strategies and population characteristics in Triplophysa strauchii, whose geographically isolated populations experience significant habitat variation in factors including resource availability and interspecific competition. Through lapillus microstructure analysis of stream versus oxbow lake populations, we demonstrate that oxbow lake habitats—characterized by abundant food resources and reduced competition—support greater longevity and larger body sizes, whereas stream populations exposed to biological invasions exhibit reduced lifespan and body size miniaturization. This differential susceptibility to environmental fluctuations highlights conservation vulnerabilities in this endemic species. Population-level analyses further reveal substantial growth potential in the Dacao Lake, contrasting with prevalent miniaturization in the Liutiao River. Effective conservation thus requires preserving native habitats, preventing and controlling invasive species, and implementing long-term monitoring of fishery resource dynamics.

Accurate age determination is fundamental for investigating fish population dynamics and growth patterns. This study used the lapillus to determine age in Triplophysa strauchii populations from an oxbow lake and a stream. Growth patterns were evaluated using three models (the Von Bertalanffy, Gompertz, and Logistic models). The oxbow lake population showed faster growth and longer lifespan (6 years in Dacao Lake; 5 years in Liutiao Stream). Conversely, the stream population displayed a trend toward smaller size and younger age. Both populations exhibited higher Fulton’s condition factor in juveniles than in adults. The species exhibited a fast-growth type, with similar fitting results across models. These findings reflect subtle differentiation in life history strategies across habitats, likely related to environmental conditions and competitive pressure from invasive species. These insights into T. strauchii life history underscore the importance of further research to support conservation and sustainable management of this endemic species.