How are zooplankton's functional guilds influenced by land use in Amazon streams?

Area of Science:

• Ecology
• Freshwater Biology
• Environmental Science

Background:

• Amazon streams, vital for biodiversity and ecosystem services, face threats from land use changes.
• Land use alterations can impact species composition and trophic dynamics, particularly in zooplankton communities.
• Understanding zooplankton functional guilds is crucial for assessing stream health in human-impacted environments.

Purpose of the Study:

• To investigate how land use influences the composition of zooplankton functional guilds in Amazon streams.
• To identify local physical-chemical variables that drive the distribution of zooplankton functional guilds along a land-use gradient.

Main Methods:

• Zooplankton and physical-chemical variables were sampled from 17 water bodies in Barcarena, Pará, Brazil.
• Forest cover, as a proxy for land use, was determined using digital image processing.
• Zooplankton species were categorized into five functional guilds based on feeding strategies.

Main Results:

• A total of 98 zooplankton taxa were recorded, with filter-feeders being the most abundant guild.
• Zooplankton functional guild composition did not significantly change across the land-use gradient.
• The distribution of functional guilds was influenced by environmental variables: scraper-feeders correlated with canopy cover, suctor/predator-feeders with total phosphorus, and filter/raptorial feeders with total suspended solids.

Conclusions:

• While land use did not alter functional guild composition, local environmental variables shape zooplankton guild distribution in Amazonian streams.
• Scraper-cladocerans may indicate less disturbed streams with higher canopy cover.
• Other functional guilds' associations with variables like phosphorus and suspended solids suggest potential impacts of altered stream conditions.