Responses of plankton communities to the introduction of grass carp into some Georgia ponds

Net plankton community structure and numbers were studied in soft-water, acidic ponds containing aquatic macrophytes, after introduction of the herbivorous grass carp (Ctenopharyngodon idella). The plankton communities in ponds with grass carp consisted of significantly fewer individuals, genera, and orders than did the communities in control ponds. Expected shifts from desirable to undesirable species of plankton did not occur. These results demonstrate that plankton blooms are not an inevitable result of stocking grass carp, and support the suggestion that macrophytes may be especially significant in nutrient cycling in soft-water, acidic systems.