Abundance and distribution of Halobates micans (Insecta : Gerridae) in the northwest Atlantic

Abstract

A seven-year survey of the marine water-strider Halobates micans in the northwest Atlantic Ocean showed highest abundance of the insects in the Caribbean Sea and Gulf Stream. The Bahama Islands and northern Sargasso Sea regions yielded relatively low abundances, and few H. micans were collected north of 35°N latitude. Regional patterns of insect abundance appear to be directly related to surface water temperature, but biotic factors such as predation and abundance of gelatinous food organisms may be important. Water strider abundance does not appear to be related to regional differences in the abundance of floating substrata. Estimates of absolute density ranged from 0 to 53,000 H. micans km −2, with densities in tropical Caribbean waters averaging 7000 km −2. Using data from 9 to 48°N latitude as an extension of data from the central Atlantic ( Cheng and Schulz-Baldes, 1981, “Meteor” Forschungsgemeinschaft-Ergebnisse, 33, 17–21), density of H. micans approximates an inverse logarithmic function of latitude. In those geographic regions where repeated annual transects have been made, the year to year variations in standing stocks of the insect are low, except in the southwest Sargasso Sea.