The Energy Budget and Population Structure of Nucula turgida in Dublin Bay

(1) The Nucula turgida (Bivalvia: Protobranchia) population in Dublin Bay had a maximum of 6 year-classes with a single spawning in September. (2) The energy budget for the population can be summarized thus: consumption, C= 2219 kJ m-2 year-'; production P = 20 kJ m-2 year; respiration, R = 66 kJ m-2 year-'; gonad output, G = 17 kJ m-2 year-l; egestion, F = 1515 kJ m-2 year-' with the imbalance probably due to an overestimate of consumption. (3) The amount of sediment processed (C, F) by N. turgida was extremely large compared to the remainder of the energy budget (P, R, G). This bivalve's major contribution to the assimilation of organic matter into the system may be indirectly through sediment modification. (4) The P:B ratio was 1:0.60, with a respiration assimilation (RA) of 64% and a net growth efficiency (NGE) of 36%. (5) Nucula turgida, compared to other bivalves, apportioned more to gonad than somatic growth due to the high lipid content of the eggs.