Biological Traits and Trait Combinations of Benthic Macroinvertebrates in a Wetland Under Hydrological Disturbance

Drought is a hydrological disturbance, predicted to aggravate in a climate change scenario. It causes habitat loss and fragmentation for aquatic organisms, including benthic fauna. The hydrological disturbance is an environmental filter, retaining only taxa possessing suitable traits for survival. Here a trait-based perspective was used to study the benthic macroinvertebrate assemblage in a seasonal wetland subjected to hydrological disturbance. Maranchery Kole wetland (a part of the Ramsar site Vembanad Kole wetland), was unusually transformed into a terrestrial landscape with discrete aquatic patches. Benthic macroinvertebrates were collected from aquatic patches. 55 categories of 10 biological traits, which could be assigned across the benthic genus were defined from literature. To delineate the faunal groups with similar trait assembly, the taxa by trait data matrix was subjected to Gower's distance‐based hierarchical agglomerative cluster analysis. Benthic macroinvertebrates belonged to 23 genera from 8 families, 4 orders, 2 classes, and 2 phyla. Their predominant traits were small body size, short life cycle duration, multivoltine life cycle, aquatic larval stage, aerial active dispersal, cocoons as resistant form, locomotion by crawling, tegumental respiration, asexual reproduction, and deposit-feeding. Traits-based classification of taxa resulted in 4 clusters. In each cluster, unique trait combinations ensured the survival of taxa. Group a persisted through desiccation resistant forms and proliferated through asexual reproduction using resource dominance strategy. Groups b and c, without desiccation resistant forms, used active aerial dispersal to colonize the aquatic patches. Group d was tolerant to unfavorable environments including morphological adaptations. Since the active dispersal trait facilitated active habitat selection in groups b and c, their presence was occasional. Groups a and d were incapable of active habitat selection due to passive dispersal traits, ensuing in their persistence throughout the study period.