Impact of Colonizer Copepods on Zooplankton Structure and Diversity in Contrasting Estuaries

Abstract The impact of the occurrence non-indigenous species (NIS) Acartia tonsa , Oithona davisae and Pseudodiaptomus marinus range-expanding copepods bifilosa Calanipeda aquaedulcis on structure diversity zooplankton communities was analyzed using 18 years (1998–2015) time series from contrasting estuaries Bilbao Urdaibai (Basque coast, Bay Biscay). Changes in were assessed by multivariate analyses taxa abundances changes descriptors alpha, beta, gamma diversity. most evident occurred at upper reaches estuary Bilbao, where an abundant less diverse brackish community, dominated NIS, A. O. succeeded a low abundance more community neritic origin. later establishment C. linked to further progressive increase seasonal pattern inner beta also significantly affected arrival NIS . In contrast, original Urdaibai, clearly far same copepod remained as best related habitats estuary.