The Impact of Water Chemistry on Zooplankton Occurrence in Two Types (Field versus Forest) of Small Water Bodies

Abstract

AbstractWe examined the influence of water chemistry on zooplankton community structure in the unvegetated zone (open water) and among different types of macrophytes (helophytes and elodeids) in 12 ponds located in two types of catchment area (mid‐forest and mid‐field).An equal occurrence of rotifers and crustaceans was found in mid‐field ponds, while rotifers prevailed over crustaceans in mid‐forest ponds which may have been due to phytoflagellate prevalence, contributing to diminishing the diversity index.We found variation in physical‐chemical features between both types of ponds with higher trophic status, confirmed by eutrophy indicators (K. quadrata or B. longirwostris) frequent occurrence, in the case of mid‐field ponds. The type of water body (forest vs. field) was the best predictor of zooplankton species distribution using DCA analysis. Two groups of zooplankton species were distinguished: (1) related to the mid‐forest ponds (representatives of genera: Cephalodella, Lepadella, Lecane, Trichocerca), where zooplankton densities positively correlated with chlorophyll a and CDOC and (2) related to the mid‐field ponds (representatives of genera: Keratella, Bosmina or Ceriodaphnia).Spatial differentiation of zooplankton community structure was also recorded with lower species diversity attributed to the open water zone compared to vegetated areas. Crustacean densities rose along the heterogeneity gradient of a habitat (from the open water to the zone of elodeids), which indicates the best refuge conditions in the most complex habitat during the daylight‐hours in the ponds with fish presence. Rotifers (especially those equipped with morphological adaptations againt predators) remained in the open water despite the presence of fish. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)