Motile cryptofauna of a coral reef: abundance, distribution and trophic potential

Abstract

The major groups of m o t ~l e cryptofauna lnhab~tlng dead coral substrata across several environmental zones of Davies Reef In the central Great Barner Reef, Austral~a, have been quantified In general terms of both numbers and b ~o m a s s the main groups of e p ~b e n t h ~c cryptofauna were harpach c o ~d copepods, g a m m a r ~d amph~pods, syll~d polychaetes and gastropod n~olluscs Other crustaceans abundant In some locat~ons were so pods t a n a ~d s and ostracods Copepods compr~sed 55 to 60 % of total number of cryptofauna over all reef locations and up to 28 % of b ~o m a s s Polychaetes were usually the dominant biomass component of the fauna Abundance of total cryptofauna vaned w t h reef locat~on, being h ~g h e s t on the fore-reef region In terms of both density and biomass Damself~sh terntones were shown to be a refuge for cryptofauna In all locat~ons of the reef Mean density of anlmals i n s ~d e territories was 58 300 m-2 an average of 3 6 tlmes h ~g h e r than on adjacent, well-grazed surfaces Cryptofaunal abundance was closely related to algal abundance and not complex~ty of the coral rock substratum It IS predicted that cryptofauna are s ~g n ~f ~c a n t consumers of epilithic algae and associated matenal In locations such as damselfish terntones, on coral reefs