Irrigation and deposit feeding by the lugworm Arenicola marina, characteristics and secondary effects on the environment. A review of current knowledge

The present review gives a short presentation of current knowledge with mai n emphasis on recent advances in the understanding of the lugworm Arenicola marina's irrigation pump, food energy requirements and feeding biology as related to bioturbation, nutrient fluxes and other secondary effects on the environment. The lugworm uses little energy (< 5 % of total metabolic outp ut) to pump water through its burrow into the sediment, but it is unlikely that the worm significantly enhances its nutritional intake by filter feedi ng as it does not filter sufficient water to gain enough nutritional benefi t. While A. marina is found in a wide range of habitats; its mode of life s ets limits on the types of sediments it can inhabit. It is critical for the lugworm to be able to pump water into the feeding pocket to adequately ven tilate its burrow and to loosen and feed on sediment particles. There appea rs to be ample food in most sediments to support the nutritional needs of A . marina. These food sources may be dead organic matter and living organism s such as bacteria, microalgae, micro- and meiofauna, but there seems to be an unnecessary dichotomy between microbial and detrital food sources in th e ongoing discussion of deposit feeder nutrition. Several food sources are probably utilised by A. marina, the balance being shifted depending on what is available in a given environment. A. marina is a good example of a "eco system engineer" as it profoundly affects both the structure and chemical n ature of as well as processes occurring within the sediment. As such A. mar ina plays an important role in affecting both energetics and material fluxe s at the sediment-water interface of the habitats in which it lives.