Herbivory drives large-scale spatial variation in reef fish trophic interactions.

Area of Science:

• Marine ecology
• Ecosystem function
• Biodiversity research

Background:

• Trophic interactions are crucial for ecosystem structure and function.
• Biodiversity loss necessitates understanding ecological responses to environmental gradients.
• Large-scale comparisons aid in comprehending ecological importance in changing ecosystems.

Purpose of the Study:

• To investigate large-scale variations in reef fish trophic interactions.
• To analyze how abiotic conditions and community structure influence feeding pressure.
• To inform conservation strategies by identifying critical functional groups.

Main Methods:

• Video recordings were used to assess reef fish feeding pressure on the benthos.
• Bite rates and individual biomass were combined to quantify feeding pressure.
• Data were collected across tropical and subtropical reefs on the Brazilian Coast (17°S–27°S).

Main Results:

• Total fish feeding pressure decreased tenfold from north to south.
• The composition of fish functional groups and species shifted along the latitudinal gradient.
• Roving herbivores, especially scrapers, showed declining feeding pressure southward, while invertebrate feeders and omnivores remained consistent.

Conclusions:

• Differential contributions of trophic categories alter the intensity and composition of fish feeding pressure.
• Feeding pressure distribution varied, being more even in the south than in the north.
• Identifying species/groups with high feeding pressure relative to biomass is key for conservation.