Spatial and temporal distributional ecology of waterscorpions (Hemipetra: Nepidae) in the Mobile/Tensaw Delta (Alabama, Ranatra nigra, R. buenoi, R. australis, R. kirkaldyi)

Spatial and temporal distributional ecology of the waterscorpion (Hemiptera: Nepidae) in the Mobile/Tensaw Delta, Mobile, Alabama, was examined from June 2001–2002. Twenty-seven sites were sampled in the fall (2001) and following spring (2002) (spatial distribution), while four sites were sampled twice a month for the entire year (temporal distribution). Distribution of mites associated with waterscorpions was also examined. A total of 575 waterscorpions were collected; this included Ranatra nigra (n = 458), Ranatra buenoi (n = 8), Ranatra australis (n = 5), and Ranatra kirkaldyi (n = 4). The occurrence (presence/absence) and abundance of R. nigra was significantly (p < 0.001) associated with distance from the Mobile Bay; in addition, R. nigra was more likely to occur in smaller, cooler streams, with lower oxygen and pH levels and higher conductivity. Rantra nigra was least abundant in the summer. Parasitism of waterscorpions with mites increased in the fall, but the abundance did not.