Published online by Cambridge University Press: 31 May 2012
The corixid Trichocorixa verticalis (Fieber) was the most abundant aquatic insect in small intertidal pools (potholes) of a New Jersey salt marsh. Aquatic samples revealed that first to third instars of T. verticalis were evenly distributed but the distribution of fourth and fifth instars was associated with the abundance of chironomid larvae. Aquatic samples of adult T. verticalis showed wide fluctuations in abundance. These fluctuations were associated with the drying up of shallower potholes, forcing adults to migrate to deeper sites that still retained water.
Light trapping of adult T. verticalis showed that there was a negative correlation between abundance and nocturnal ambient air temperature. This correlation indicated that T. verticalis dispersed on cooler nights to minimize water loss that would have been high had they emerged from warm pothole water temperatures into warm ambient air temperature. Spatial heterogeneity in the abundance of T. verticalis in light-trap samples was associated with differences between plots in water-surface area within a 100 m radius of the light trap. Dispersive behavior of T. verticalis is discussed in relation to harsh, ephemeral, and unpredictable salt-marsh aquatic habitats.