Cladocerans and macrophytes: network and resistance to extinctions

Abstract Macrophytes are important in structuring various aquatic communities, particularly cladocerans. Our findings highlight that plant structural complexity and functional life forms (specifically free-floating and submerged species) act as key drivers of interaction density and network stability, providing essential microhabitats for cladocerans in tropical oxbow lakes. Ninety sampling units from three lakes within a Conservation Unit in Acre were used, where macrophytes and cladocerans were collected. A bipartite network was constructed with 39 macrophyte species and 20 cladoceran species, followed by a directed removal of macrophytes to simulate species extinctions. The resulting network showed low specialization and relatively high connectance, suggesting a predominantly generalist pattern, in which cladocerans share the use of different macrophytes as microhabitats without evident selectivity. The structural robustness analysis of the interaction network revealed that random removal of plant species led to a continuous reduction in the total number of interactions (links), especially between the tenth and thirteenth steps, suggesting that the nested structure of the network is resilient to initial random losses but vulnerable to accumulated extinction. This result highlights the need for conservation of shallow lakes, environments under threat, especially due to global climate change.