Structure and functional composition of macroinvertebrate communities in coastal plain streams across a precipitation gradient

Abstract

1. Climate change is expected to alter rainfall and temperature regimes across the world. The hydrology and riparian zone vegetation of lotic ecosystems are tightly linked to rainfall and a mechanistic understanding of the effects of rainfall on lotic ecosystems is needed to forecast the ecological impacts of climate change.However, it is difficult to isolate rainfall effects from other environmental variables that covary across climates. To address this, we leveraged a unique steep rainfall gradient with few covarying changes in elevation, temperature, and geology to evaluate the effects of rainfall on stream invertebrate communities.2. We surveyed nine streams in the Texas Gulf Coast Prairie distributed along a 550-1,350 mm/year rainfall gradient. Four sites were classified as drier semiarid streams (<750 mm annual rainfall) and five sites were classified as wetter sub-humid streams (>750 mm annual rainfall). A suite of characteristics including benthic invertebrate community metrics, flow conditions, and water quality variables were assessed monthly for 14 months at each site to relate precipitation regime to stream structure and function.3. Precipitation regime was observed to be a master explanatory variable. As annual rainfall increased, the flow environment became more stable within seasons and predictable across seasons, influencing spatial structure and temporal variability of invertebrate community composition. Wetter streams were dominated by slower growing taxa without adaptions for desiccation resistance and strong dispersal. Wetter sites displayed seasonal variation in community composition and species richness, whereas temporal variation in communities in drier streams was controlled by stochastic variation in flow conditions. 4. These observations show that differences in local annual rainfall correlated with major changes to community structure and functional composition. We hypothesise that this association is related to the connection of rainfall to hydrological stability, particularly the frequency of low flow disturbances, and the

Long‐term climate and hydrologic regimes shape stream invertebrate community responses to a hurricane disturbance

“…This potentially offers an explanation for climate-mediated faster recovery times (Robinson, 2012). In contrast, as discussed in Carvallo et al (2022) and observed here, taxa abundant in wetter sites including amphipods and mayflies (Cloeon spp.) are relatively slow-growing and not good dispersers; thus, would take longer to recover after a storm event.…”

“…All sites were wadable and had a U.S. Geological Survey (USGS) flow gauge within 200 m of the sampling area. Previous work on this study system revealed that rainfall driven variation in hydrology and environmental conditions is the dominant driver of stream invertebrate community structure (Carvallo et al, 2022;Kinard et al, 2021).…”

“…The region is otherwise similar, exhibiting comparable elevation (14-62 m a.s.l. ), soil geology (Quaternary and sedimentary), and air temperatures (21-22°C) (Carvallo et al, 2022;Falcone, 2011).…”

Basin‐scale variables drive macroinvertebrate biomass in low‐order streams across different mountain ecoregions

“…Thus, it is not surprising that the basin‐scale variables in our study explained more variance than patch‐ and reach‐scale variables. Mean daily precipitation drives the hydrological cycle and flow regime, which are the master variables in running water ecosystems (Carvallo et al, 2022; Patrick et al, 2019; Poff et al, 1997). They can affect the growth rate and, thereby, the biomass of invertebrate communities both as determinants of local conditions and through changes in systems stability.…”

Macroinvertebrate conservation in river ecosystems: Challenges, restoration strategies, and integrated management approaches

“…This could lead to localized extinctions, diminished biodiversity, and changes in community composition (Bonacina et al 2023;Eady et al 2013). Alterations in rainfall patterns and water regimes contribute to more frequent and severe droughts and floods, disrupting habitat availability and stability (Carvallo et al 2022). Drought conditions lower water flow, resulting in habitat reduction and heightened resource competition, whereas flooding can displace macroinvertebrates and erode essential habitat features.…”