Distribution of Mysids (Crustacea: Mysidacea) in Auckland Region, New Zealand

Abstract

Given the ecological significance of mysids in brackish and freshwater food chains and the potential importance in toxicity testing in estuarine systems, it is important to understand the distribution of these animals. However, to date, few studies have been undertaken on mysids in the Auckland region. DThe main focus of this study was to find out the distribution of estuarine mysids in this region. Reconnaissance surveys took place to locate mysid habitats in the estuarine waters entering the Manukau Harbour and the East Coast estuarine environments from May of 2006 to January 2009. The samples were taken using a hand held dip net with 500 µm mesh size along an eighty meter transect at the edge of the stream during day time at low tide. At each site four replicate surveys were undertaken (transects of 10 m length, 10 m apart). Five species of mysids have been identified from and are described for estuarine environments in the Manukau Harbour and along the Auckland East Coast: the sometimes sympatric Tenagomysis chiltoni and T. novaezealandiae, and the non-sympatric and patchily distributed Gastrosaccus australis, T. macropsis and a potentially new Tenagomysis sp.. The present distributional studies in the North Island reflects that the native mysid T. novaezealandiae is the dominant mysid species along the east coast, and the most geographically widespread species on both east and the west coasts, while T. chiltoni was equally dominant with T. novaezealandiae in the Manukau Harbour. G. australis and T. macropsis reported from North Island estuarine waters for the first time. The salinity ranges where species occurred were different: T. chiltoni 0-18‰, T. novaezealandiae 0-26‰ and G. australis 1.5-12.6‰. T. chiltoni, Tenagomysis sp. and T. novaezealandiae shows that the higher percentages of females than males.