Distribution, body size, and brood characteristics of four species of mysids (crustacea: Peracarida) in the avon-heathcote estuary, new zealand

Abstract

Four species of mysids are resident in the Avon-Heathcote Estuary, Christchurch. Tenagomysis macropsis is by far the most abundant daytime species and has a wide distribution, not linearly correlated with salinity. Tenagomysis novae-zealandiae and T. chiltoni are much less abundant, increase in numbertoward the upper estuarineregion, and (especially T. chiltoni) have distributions significantly correlated with salinity (P < 0.05–0.001). T. chiltoni has a spring/summer population maximum. Gastrosaccus australis appears to be an obligate nocturnal plankter and its; distribution in the system is unresolved. The largest mysid was T. chiltoni and the smallest T. novae-zealandiae, although there was considerable intraspecific size variation. For all 3 Tenagomysis species, males were mature at a smaller size than females, whereas the opposite was true for G. australis. For each species, ovigerous females generally achieved the maximum size recorded. Embryo numbers carried in the marsupium ranged from 4 to 25 for T. macropsis, from 6 to 19 for T. novae-zealandiae, and from 22 to 39 for T. chiltoni. Embryo sizes for the New Zealand species are in accord with the range found generally for coastal mysids. © Crown copyright 1989.