# The Influence of Habitat Heterogeneity and Human Disturbance on Trophic Interactions of Sebastiscus marmoratus and Scorpaenopsis cirrosa in Wanshan Archipelago

## TL;DR

This study explores how habitat differences and human activity affect the feeding habits and competition between two scorpionfish species in the Wanshan Archipelago.

## Contribution

The study reveals region-specific foraging strategies and niche differentiation in scorpionfish influenced by human disturbance and habitat heterogeneity.

## Key findings

- δ13C values showed regional differences in food sources for the two scorpionfish species.
- S. cirrosa exhibited a broader trophic niche and more flexible feeding strategy compared to S. marmoratus.
- Higher human activity correlated with increased competition between the species at Guishan Island.

## Abstract

Habitat heterogeneity and human disturbances drive variations in interspecific interactions among fish species. Trophic niche analysis is a crucial approach for understanding these interactions. This study investigates the interspecific interaction mechanisms of two scorpionfish species,
Sebastiscus marmoratus
and
Scorpaenopsis cirrosa
, across different habitat conditions in the Wanshan Archipelago of the Pearl River Estuary. Three island groups—Guishan Island, Wailingding Island, and Dongao & Wanshan Islands—were selected as study sites. Using carbon and nitrogen stable isotope analysis, we examined variations in their trophic relationships. The results revealed significant regional differences in the δ13C values of
S. marmoratus
and
S. cirrosa
(p < 0.05), indicating regional variation in their food sources. Bayesian mixing model analysis showed that at Guishan Island, annelids constituted the primary food source for both species. However, at Wailingding Island and Dongao & Wanshan Islands, their reliance on annelids significantly decreased, with a preference shift towards mollusks, reflecting region‐specific foraging strategies and niche differentiation. The δ15N values of the two species did not exhibit significant regional differences, suggesting that
S. marmoratus
and
S. cirrosa
occupy similar trophic levels across different regions. Trophic niche metrics, including CR, NR, CD, and TA, indicated that
S. cirrosa
has a broader trophic niche, suggesting a more flexible feeding strategy and a potential competitive advantage in resource utilization. The two species exhibited overlapping trophic niches, with distinct regional variations. Notably, at Guishan Island, where trophic niches were the broadest, potential competition between the species was most pronounced, which may be associated with higher human activity intensity. Differences in ecosystem structure among islands contributed to variations in food resource availability and niche space, ultimately shaping the foraging behaviors and adaptive strategies of
S. marmoratus
and
S. cirrosa
across regions. These findings provide theoretical insights into interspecific interactions in heterogeneous habitats and inform fisheries resource conservation.

This study investigates how habitat heterogeneity and human activity shape trophic interactions between two scorpionfish species (
Sebastiscus marmoratus
and
Scorpaenopsis cirrosa
) in China's Wanshan Archipelago. Stable isotope analysis revealed regional shifts in their diets (e.g., annelids to mollusks) and broader niche use by
S. cirrosa
, with heightened competition in high‐human‐activity areas, underscoring the need for habitat‐specific conservation strategies. These findings highlight how ecosystem structure and anthropogenic pressures drive resource partitioning in marine species.