Physiological and life history responses in a mayfly (Callibaetis floridanus) inhabiting ponds with saltwater intrusion

Freshwater salinity varies in natural systems and plays a role species distribution. Anthropogenic alterations to freshwater regimes include sea level rise subsequent intrusion of saline waters inland habitats. While mayflies are generalized be sensitive increasing salinity, we still know remarkably little about the physiological processes (and their plasticity) that determine performance changing world. Here, explored life-history outcomes plasticity population Callibaetis floridanus (Ephemeroptera: Baetidae) from coastal pond routinely experiences saltwater intrusion. We reared naiads egg hatch adulthood across gradient salinities (113, 5,020, 9,921 μS/cm). Radiotracer flux studies ( 22 Na, 35 SO 4 , 45 Ca) were conducted at each revealing positive association between ionic concentration uptake rates. However, influence rearing history on influx rates was apparent when transferred respective water other experimental conditions. For example, observed low treatment (113 μS/cm) had 10.8-fold higher Na than μS/cm 113 μS/cm. Additionally, acclimated exhibited reduced ion-rich relative those more dilute conditions (e.g., water, 5,020 1.5- 1.1-fold naiads, respectively). found no significant changes survival (80 ± 4.4%, mean s.e.m.) or naiad development time (24 0.3 days, these treatments but did observe 27% decrease subimago female body weight most condition. This reduction associated with oxygen consumption Collectively, data suggests adapted C. may energetically challenged conditions, which differs previous observations mayfly species.