COLONIZATION AND FISHERY POTENTIAL OF A COAL-ASH ARTIFICIAL REEF, POOLE-BAY, UNITED-KINGDOM

The colonization of an experimental reef composed of blocks of stabili zed coal-fired power station waste (pulverized fuel ash (PFA) and gyps um), which was installed in Poole Bay in June 1989 is described. The r eef consists of 50 tons of blocks (each 40 x 20 x 20 cm) formed into e ight conical units, each 1 m high by 4 m across on an area of seabed 3 0 m x 10 m. The reef lies on a fiat sandy seabed (10 m below chart dat um) 3 km distant from natural rocky outcrops. The eight units represen t three different PFA/gypsum mixes, each replicated, and two concrete controls. Colonization by epibiota was monitored using direct observat ion and photographic recording of block surfaces. Analysis of the resu lts using CLUSTAN 3/PC clustering software did not reveal any differen ces in the biota colonizing the three PFA/gypsum mixes or between the colonizers of the PFA/gypsum mixes and the concrete controls. Epibiota showed seasonal variations in abundance throughout the year overlain with a progression in the numbers of species present and a maturation of the population towards the epibiotic populations seen on local natu ral reefs. Adult lobsters (Homarus gammarus) and crabs (Cancer pagurus ) from the local natural reefs were recruited to the reef within 3 wee ks. Acoustic and conventional tagging studies revealed that some lobst ers showed considerable site loyalty, with recorded residence time of 368 days. The most numerous shoaling fish congregating around the reef units has been the pouting, Trisopterus luscus, a small gadoid. Shoal size was commonly estimated at around 200 individuals per reef unit. Summer biomass estimates of pouting wet weight, using published weight to length conversions, were 207-1572 kg.ha(-1) in the vicinity of any one of the eight reef units. Several species using the reef were obse rved to be reproducing there. These include corkwing wrasse (Crenilabr us melops), lobster (Homarus gammarus), spiny spider crabs (Maja squin ado), velvet swimming crab (Liocarcinus puber), hermit crabs (Pagurus bernhardus), whelks (Buccinum undatum) and the nudibranch (Archidoris pseudoargus). Assessment of infauna suggests that the infaunal populat ion in the vicinity of the reef was not overtly affected by the presen ce of the reef. Sediment granulometry did not alter significantly betw een May 1989 and July 1991.