Resident mysids: secondary production, consumption, and trophic role in a coral reef lagoon

Abstract

Annual patterns in standing stock, production, and consumption of mysids on the lagoon floor at Davies Reef on the Great Barrier Reef mirrored the distribution and abundance of the more ubiquitous species — Erythrops nana, Doxomysis littoralis, Anisomysis pelewensis, and Prionomysis stenolepis. Mysids were most abundant during austral spring and early summer (September to December), which coincided with the seasonal maximum in lagoon deposition rates of detritus rather than the peak time of primary production (February to May). Secondary production, excluding the relatively large schooling species A. australis, ranged between 0.2 mg C m -2 d -1 in May and 6.5 mg Cm -2 d -1 in October and was similar to estimates for other tropical or sub-tropical species, but was either comparable to or very much lower than estimates for temperate species. However, daily pro- duction:biomass (P:B) ratios for lagoon mysids were extremely high compared with cold-water spe- cies. Diurnal feeding ranged between 0.5 and 16.3 mg C m -2 d -1 , and accounted for approximately 1 to 21% of detritus deposition at shallow sites within the lagoon. The hyperbenthic mysid community consumed less detritus than either the sediment invertebrate infaunal or bacterial communities, but similar quantities to the water column zooplankton community. As large areas of Indo-Pacific coral reefs and atolls are either sandy lagoons or back-reef slopes — appropriate habitat for these relatively large, abundant, reef-resident zooplankters — the role of mysids within coral reef ecosystems through the remineralization of detritus must be substantial.