Cryptobenthic fish as bioindicators: Community shifts along urban pollution

Area of Science:

• Marine Ecology
• Urban Ecology
• Environmental DNA (eDNA)

Background:

• Coastal ecosystems face degradation from urbanization, affecting biodiversity and stability.
• Cryptobenthic fishes, crucial for ecosystem function, are understudied indicators of human impact.

Purpose of the Study:

• Investigate drivers of cryptobenthic fish assemblages along a pollution gradient in Hong Kong.
• Assess the role of urbanization and nutrient levels on these fish communities.
• Evaluate cryptobenthic fishes as indicators of anthropogenic disturbance in marine environments.

Main Methods:

• Combined collection-based surveys and environmental DNA (eDNA) techniques.
• Analyzed cryptobenthic fish assemblages across a pollution gradient in Hong Kong.
• Correlated species composition with environmental parameters, particularly nutrient levels.

Main Results:

• Cryptobenthic fish species richness was comparable to pristine sites, but community composition varied with pollution.
• Highly impacted sites showed higher abundance of species like Tridentiger trigonocephalus and Gobiopsis macrostoma, linked to elevated nutrients.
• Species like Gobiospsis arenaria and Parablennius Yatabei were found exclusively in low-nutrient environments, with nitrogen identified as a key driver.

Conclusions:

• Cryptobenthic fish assemblages are significantly influenced by nutrient pollution in urbanized coastal areas.
• These fish exhibit species-specific tolerances to nutrient levels, highlighting their sensitivity.
• Cryptobenthic fishes serve as valuable ecological indicators for monitoring biodiversity and impacts of urbanization in marine ecosystems.