natural lakes, and its effects on zooplankton community composition

• Main Authors: Ian C. Duggan, Martin W. Neale, Karen V. Robinson, Piet Verburg, Nathan T. N. Watson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: New Zealand; Copepods; Rotifer
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.661.8779; http://aquaticinvasions.net/2014/AI_2014_Duggan_etal.pdf

The North American calanoid copepod Skistodiaptomus pallidus is an emerging invader globally, with non-indigenous populations recorded from constructed waters in New Zealand, Germany and Mexico since 2000. We examined the effects of S. pallidus establishment on the zooplankton community of a natural lake, Lake Kereta, where it was first recorded in late-2008, coincident with releases of domestically cultured grass carp (Ctenopharyngodon idella). Although not present in any of our samples prior to August 2008, S. pallidus was found in all samples collected in the subsequent five years. ANOSIM indicated zooplankton community composition significantly differed between samples collected before and after S. pallidus invasion, whether the invader was included in the analysis or not. Zooplankton species affected most greatly were the copepods Calamoecia lucasi and Mesocyclops sp., which decreased in their relative importance, and the cladocerans Bosmina meridionalis and Daphnia galeata, which increased. Rotifer species were relatively unaffected. As the length of grass carp released were>6.5 cm, direct predatory effects by this species on the zooplankton community are unlikely. Associated reductions in macrophyte biomass could explain increases in the relative abundances of planktonic cladocerans (B. meridionalis and D. galeata).