Michael G. Peterson, Kevin B. Lunde, Ming-Chih Chiu, Vincent H. Resh
Western North American Naturalist 77 (2), 176-188, (30 June 2017) https://doi.org/10.3398/064.077.0205
Seasonal wetlands are important habitats for biodiversity of both invertebrate and vertebrate fauna. Many aquatic species have life history traits adapted to colonizing and developing in temporary aquatic habitats, and these traits influence the annual succession of the macroinvertebrate community. The chronology of taxon appearance and the variation in relative abundances during the hydroperiod are important for understanding population dynamics, trophic interactions, and responses to drought. This study investigated the successional changes in macroinvertebrate abundances in a seasonal wetland in northern California. Water quality parameters were measured regularly, including dissolved oxygen, temperature, pH, surface area, and specific conductance during the wet season ( January–July) in 2007–2009. Macroinvertebrates were collected with net sweeps (mesh > 500 mm), and the presence of life stages of amphibians were visually observed from March to June each year. As the hydroperiod progressed, wetland surface area decreased, while water temperature and specific conductance increased. Macroinvertebrate abundance increased with the progression of the hydroperiod, and the richness of macroinvertebrate predator taxa tripled from 2 families in March to 6 families in June. The earliest part of the hydroperiod in the wetland was dominated by Cyzicus clam shrimp and Linderiella occidentalis fairy shrimp. Limnephilus caddisfly larvae were few in number but were found exclusively in the early season. Sequential changes of dominant invertebrate taxa and relative abundances of macroinvertebrates were evident, particularly among several macroinvertebrate predators. Among these predators, the early-season community was dominated by larval dytiscid beetles, while later-season communities demonstrated increased predator richness (e.g., Notonecta backswimmers) and were dominated by Lestes damselflies. Larvae of the vertebrate predator Taricha torosa, which may act as a top predator, were present during the later stages of the hydroperiod. The phenology of individual aquatic taxa and their specific life history strategies may impact the sensitivity of macroinvertebrate populations to increased annual variation in hydroperiod that may result from climate changes in this region.