Annual macrofauna production in a Venus community

Abstract

A station representative of the Venus community in Carmarthen Bay, S. Wales, has been sampled regularly between February 1974 and March 1975 with a Knudsen sampler, Day grab and naturalist's dredge. Estimates of annual production of the 15 most important macrofauna species in the community have been made using the techniques of cohort growth analysis. Annual production, mean annual biomass (g ash-free dry wt./m 2) and the P B ratio for each species were as follows: Pharus legumen; P = 16.119, B = 28.816, P B = 0.56 . Spiophanes bombyx; P = 3.345, B = 0.688, P B = 4.86 . Ensis siliqua; P = 1.372, B = 5.100, P B = 0.27 . Nephtys hombergi; P = 0.935, B = 0.492, P B = 1.90 . Donax vittatus; P = 0.721, B = 0.344, P B = 2.10 . Magelona papillicornis; P = 0.685, B = 0.625, P B = 1.10 . Venus striatula; P = 0.616, B = 1.496, P B = 0.41 . Ophiura texturata; P = 0.458, B = 0.672, P B = 0.68 . Tellina fabula; P = 0.292, B = 0.325, P B = 0.90 . Glycera alba; P = 0.281, B = 0.291, P B = 0.97 . Sigalion mathildae; P = 0.165, B = 0.376, P B = 0.44 . Lumbrineris latreilli; P = 0.120, B = 0.092, P B = 1.30 . Tharyx marioni; P = 0.015, B = 0.018, P B = 0.79 . Astropecten irregularis; P = 0.0004, B = 0.073, P B = 0.005 . Echinocardium cordatum; P = −0.012, B = 5.138, P B = −0.02 . The total annual production was 25.815 gm −2 year −1 and the mean biomass 45.793 gm −2, giving an overall P B for the community of 0.56. These values are discussed in relation to other communities for which comparable data are available.