Epsilon Archive for Student Projects

Abstract

Tropical coral reefs are among the most biologically diverse ecosystems, supporting
essential ecological functions while providing income and food security for coastal
populations. Reef fish communities are shaped by environmental factors such as
depth, habitat structure, and trophic interactions. Tanzania’s coral reefs, including
those around Unguja Island, Zanzibar, are vital to local fisheries, but fishing
pressure may impact fish communities across depth strata. This study examines
variations in fish communities across two depth strata (shallow: ≤ 10 m and deep:
> 10 m) on coral reefs around Unguja Island. It focuses on species richness, the
relative abundance of the entire fish community, commercially important species,
and trophic groups. Fish communities were sampled at six urban areas using baited
remote underwater video systems. Depth significantly influenced fish community
structure, including commercial species and trophic groups, with species contributing
to these dissimilarities exhibiting greater abundance in shallow strata. Habitat
factors, such as hard live coral and habitat complexity, significantly contributed to
dissimilarities in fish communities across strata, although these factors themselves
differed significantly between depth strata. Contrary to previous studies suggesting
depth refuges for fish, this study found no evidence supporting this phenomenon.
The findings highlight that depth and habitat significantly influence fish communities
on coral reefs. Future studies should evaluate biomass and investigate fish communities
of locally important commercial species to gain a deeper understanding of
their structures. This knowledge is critical for developing sustainable management
strategies to safeguard this vital resource for the communities that depend on it.