Thu, Aug 05, 2021:On Demand
Background/Question/Methods
Zooplankton communities in small ponds are noted for their functional role in linking a pond’s primary producers to higher trophic levels as energy and nutrients flow through the zooplankton community. Zooplankton diversity likely contributes to this functional role. In the case of newly constructed permanent ponds we expect zooplankton diversity to be low initially, because community assembly in this new habitat relies upon the colonization of individual species and the successful establishment of each new taxa. Thus the ability of the zooplankton community to functionally support higher trophic levels in a constructed pond may change during the pond’s ontogeny, emphasizing the importance of community assembly. Our objective was to examine the abundance and composition of the zooplankton community in a newly created fishless permanent pond during the four years following pond construction (2016-2019). Specifically we tracked population and community change across the four years and also compared the seasonal pattern of abundance among the four years for specific taxa. We sampled the young pond monthly from March to September each year using integrated tube samplers to quantify population abundance for different zooplankton taxa. We also sampled Chl a levels as an index of the pond’s primary producers.
Results/Conclusions We found that different zooplankton taxa showed peaks in abundance at different points in the pond’s ontogeny. For instance, copepod nauplii and rotifers (Keratella cochlearis) were significantly more abundant in the year following the pond’s construction (2016) and then stabilized at lower population densities in later years. Comparisons of seasonal abundance for nauplii and Keratella indicated no significant difference among years in the pattern of abundance from March to September. In contrast, early in the pond’s development large cladocerans (Simocephalus, Daphnia & Ceriodaphnia) were relatively rare, but population densities rose in years 3 and 4 post-construction. Seasonal patterns of abundance were similar among years for the large cladocerans, and there was an effect of time such that maximal density occurred in late summer (August & September). As the zooplankton community developed in this permanent pond it appears that seasonal patterns of population density (March-September) were somewhat repeatable even as new taxa colonized the pond in the years following pond construction. Differences in the composition of the zooplankton community across four years highlight the dynamic nature of community assembly for zooplankton in newly constructed permanent ponds, which may have consequences for the development of other components of the aquatic community.
Results/Conclusions We found that different zooplankton taxa showed peaks in abundance at different points in the pond’s ontogeny. For instance, copepod nauplii and rotifers (Keratella cochlearis) were significantly more abundant in the year following the pond’s construction (2016) and then stabilized at lower population densities in later years. Comparisons of seasonal abundance for nauplii and Keratella indicated no significant difference among years in the pattern of abundance from March to September. In contrast, early in the pond’s development large cladocerans (Simocephalus, Daphnia & Ceriodaphnia) were relatively rare, but population densities rose in years 3 and 4 post-construction. Seasonal patterns of abundance were similar among years for the large cladocerans, and there was an effect of time such that maximal density occurred in late summer (August & September). As the zooplankton community developed in this permanent pond it appears that seasonal patterns of population density (March-September) were somewhat repeatable even as new taxa colonized the pond in the years following pond construction. Differences in the composition of the zooplankton community across four years highlight the dynamic nature of community assembly for zooplankton in newly constructed permanent ponds, which may have consequences for the development of other components of the aquatic community.