Short-Term Drought Impacts are Influenced by Annual Flow Patterns and Fish Life History Strategies in North Texas

Sixteen fish communities were assessed in North Texas, USA, in spring 2022 and 2023, separated in time by a severe drought. To assess the influence of flow patterns on drought response, mean low flow patterns in August and annual flow variation (flow stability) were measured for each site. Sites were then assigned drought risk scores based on these variables, and the data was split into higher drought risk and lower drought risk groupings. A Non-metric multidimensional scaling (NMDS) analysis of pre and post drought communities was performed, and paired Euclidean distance was measured to indicate annual change. Analyses showed that annual community change patterns were significantly stronger in the higher risk sites than the lower risk sites, and this pattern was mainly driven by species losses. To determine drought impacts relative to species life history strategies a dataset of six life history trait values for each species was used in another NMDS analysis together with Archetype Analysis to define more opportunistic, more equilibrium, and more periodic strategies among the fish species of the region. More opportunistic species increased in mean relative abundance after drought by 4.8%, while less opportunistic species (equilibrium and periodic) decreased by 2.7%, which indicated a significantly different annual response to the drought. This research shows that opportunistic vs non-opportunistic life history strategies can relate to species short term drought risk and response, and that annual low flow and variability patterns are good indicators of potential short-term community change following droughts, which can be useful to better understand species risk and community response in drought prone regions.