Comparison of biomass and percentage cover of sessile epibiota on the Poole bay artificial reef

The Poole Bay Artificial Reef (deployed June 1989) was the first artificial reef made of concrete and stabilised coal-waste blocks in the UK. In this study, percentage cover (determined by a laboratory-based random point method) and biomass lash-free dry weight) of sessile epibiota on reef blocks were recorded every 5-7 weeks from April to November, in 1990 and 1991. Biomass, w, was compared with percentage cover, L, for five categories of sessile epibiota on the 400 x 200 mm faces of the reef blocks. This resulted in the following regression equations (all p < 0.01): w = 1.70 (arcsin root L/100)(1.91), r(2) = 0.47 for ascidians; w = 7.94 (arcsin root L/100)(2.10), r(2) = 0.88 for eggs; w = 2.09 (arcsin root L/100)(3.26) r(2) = 0.71 for erect organisms; and w = 3.02 (arcsin root L/100)(2.65) r(2) = 0.60 for sponges. The slopes of these regression lines were not significantly different, however, the elevation for the eggs was significantly different to the other elevations. Thus a general relationship could not be derived. A significant regression could not be derived for encrusting organisms (barnacles, tube worms, molluscs and encrusting bryozoans).