Subtidal benthic macroinfaunal assemblages in tropical estuaries: generality amongst highly variable gradients

Area of Science:

• Estuarine Ecology
• Marine Biology
• Benthic Ecology

Background:

• South American estuaries are underrepresented in ecological modeling.
• Estuarine studies often fail to sample the full salinity gradient, limiting generalizability.
• Understanding benthic macrofauna distribution is crucial for estuarine ecosystem health.

Purpose of the Study:

• To investigate benthic macrofauna distribution across salinity gradients in three tropical South American estuaries.
• To identify consistent patterns in benthic assemblages despite varying estuarine characteristics.
• To propose a general empirical model for benthic invertebrate distribution along tropical salinity gradients.

Main Methods:

• Sampling of benthic macroinfauna and sediment at ten stations along three tropical estuaries.
• Collection of six replicates per station for macroinfauna, sediment grain size, and inorganic contaminant analyses.
• Statistical analysis of spatial distribution patterns and diversity metrics (family level) along the salinity gradient.

Main Results:

• Finer sediments were observed in lower estuarine portions compared to upper portions.
• Benthic macrofauna diversity (family level) decreased from marine to freshwater environments.
• Spatial differences were the primary drivers of benthic assemblage structure, with consistent distribution patterns observed across estuaries.

Conclusions:

• Consistent patterns of benthic macrofauna distribution exist along tropical salinity gradients, even in estuaries with diverse characteristics.
• The findings support the development of a general empirical model for predicting benthic invertebrate distribution in tropical estuaries.
• This model can be tested and refined in other estuarine systems globally, enhancing ecological understanding.