Temporal and Spatial Variations in Copepod (Crustacea) Communities in Groundwater in the Rocky Glades of Everglades National Park (Florida, USA)

Abstract

ABSTRACT We studied species composition and individual abundance of copepods in the surficial aquifer in short-hydroperiod habitats of Everglades National Park by collecting copepods from different depths in wells for three consecutive years. The wells were cased and open at depths that corresponded to highly permeable layers. Groundwater communities were dominated by surface copepods which colonized groundwater mainly during the dry season. The total number of copepods collected decreased exponentially with depth; the decrease in copepod numbers and species richness below the 3 m depth was due to high permeability of the limestone above 3 m depth and to the presence of a semipermeable layer at lower depths. The calanoid Osphranticum labronectum and the cyclopoids Orthocyclops modestus and Thermocyclops parvus that were dominant in the collections can be considered stygophiles at least in Everglades National Park. Copepod groundwater communities were most similar on a local scale, indicating that when local surface water populations enter groundwater by following the receding water table, they do not disperse widely through the groundwater system. Densities of groundwater populations of stygophiles were low, which increases their risk of being impacted by changes in hydrology.