Anthropic impact on microbial food webs of Amazonian lakes

• Grant number: 25/20918-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Principal Investigator: Gustavo Quevedo Romero
• Grantee: Elvis Chen
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 19/08474-8 - Freshwater ecosystems under climate change: impacts across multiple levels of organisation, AP.PFPMCG.TEM

Abstract

Knowledge about 'who eats whom' in microbial communities is limited, especially in aquatic communities. This is due to a lack of specific dietary information, such as data on the stomach contents of microorganisms. In addition, little is known about the trophic ecology of phytoplankton, ciliates, rotifers, and microcrustaceans. Consequently, establishing direct feeding relationships between these aquatic communities is a challenging task. One way to circumvent this problem is to establish feeding relationships based on functional traits of microorganisms. For example, using the body size of prey and predators, assuming that predators consume only prey within specific size ranges. Another approach is to consider the type of feeding of predators, as in the case of filter feeders, which tend to consume smaller prey than those consumed by raptorial predators. In this scientific initiation project, we will use data from microbial communities (phytoplankton, ciliates, rotifers, and microcrustaceans) sampled in 31 lakes in the Amazon floodplain. Our goal is to establish food interactions between species of phytoplankton, ciliates, rotifers, and microcrustaceans. To this end, detailed bibliographic research will be conducted to identify the topology of microbial food webs (i.e., define who eats whom in the community). To this end, we will gather ecological (e.g., type of feeding) and morphological (e.g., body size) information on the organisms. With this information, we will construct consumer-resource relationship spreadsheets. Using these spreadsheets, we will estimate food web metrics, including: number of nodes (S), number of links (L), link density (L/S, where S is the number of nodes) and connectance (C). Finally, we will estimate the land cover used for human activities on each lake, which will include agricultural cover, pastures and cities. The prediction that the intensification of human activities on lakes (i.e., greater agricultural and pasture coverage) will be related to a reduction in the number of nodes, the number of trophic links, the density of links, and the connectance of microbial food webs. It is expected that less degraded lakes (with less human activity) will support more complex microbial food webs, with a greater number of trophic links between species of phytoplankton, ciliates, rotifers, and microcrustaceans. (AU)