Meeting Abstract
P3-69 - Developing a mayfly model to assess salinity stress and acclimation in freshwater ecosystems Orr, SE*; Cochran, JK; Buchwalter, DB; North Carolina State University, Raleigh, NC; North Carolina State University, Raleigh, NC; North Carolina State University, Raleigh, NC seorr@ncsu.edu
Freshwater ecosystems are becoming increasingly salty due to human activities and ecologists are observing steep declines in some sensitive groups of aquatic insects, such as mayflies. However, no laboratory models exist to represent these sensitive taxa and the ionoregulatory biology of these organisms remains understudied. Our lab is developing the Baetid mayfly, Neocloeon triangulifer, into a model organism to further assess the physiological consequences of salinity stress. Previous work in our lab has revealed that high salinities delay development, decrease body mass and egg production, and ultimately reduce survival. We used radiotracers to show that in naïve larvae, ion transport rates are concentration dependent. However, in the case of Na, we observed that acclimated larvae maintain a consistent Na uptake rate (± SEM) of 38.5 ± 4.2 µg Na g-1 hr-1 across ambient Na concentrations of 0.9 to 15 mg L-1, demonstrating significant acclimatory capacity. At 157 mg L-1 Na, however, this “preferred” rate of Na transport was exceeded by 89% despite the acclimatory transport rate response being 50% lower than those observed in naïve larvae at this concentration. In contrast, while the acclimatory response of larvae to elevated SO4 was substantial (88% lower transport rates than those observed in naïve larvae), the SO4 transport rates were still 13-fold higher than those of control larvae, and resulted in toxicity, while the elevated Na treatments were tolerated. These results suggest that excessive SO4 uptake in acclimated larvae is an energetic drain that results in developmental delays. Combining molecular and physiological techniques, we can link multiple levels of biological organization (e.g., mRNA expression, ion flux rates, and life history outcomes) to determine the overall effects of freshwater salinization in this mayfly model.