'Biogenic structures as refuge for common sole (Solea solea) and brown shrimp (Crangon crangon): Experiments in artificial Lanice conchilega reefs

Lanice conchilega reefs have been considered important nursery areas for juvenile flatfish species. This is due not only to the high food availability found in these habitats but also because the tube structures of the polychaete may serve as refuge from predators and physical disturbances. This paper evaluates the effect of the biogenic tube structures of Lanice conchilega as potential refuge for juvenile common sole (Solea solea). To only test for the response of the fish to the physical advantage of the tube structure; mimics of L. conchilega tubes were used. As a predator, the shrimp (Crangon crangon) was incorporated as a potential threatening stimulus to enforce the behavior of the fish. Experiments were conducted at three different water velocities 0, 3, and 5 cm s⁻¹ in a 12 m² surface volume experimental flume and in flow-through tanks for experiments at zero velocity. Organisms were exposed simultaneously to three different habitats: two artificial L. conchilega reef habitats consisting of 3 000 ind m⁻¹, representing a high tube density and 500 ind m⁻¹, representing a low tube density. The third habitat was the control of which tubes were absent. Results demonstrated that juvenile S. solea is attracted to a habitat with tube structures although preference might vary depending on the density of the structures and the size of the organism. Flume experiments revealed that both species had a preference for the habitat with low tube densities and the control habitat was favored over the habitat with high tube densities. In the tank experiments, C. crangon still preferred the habitat with the low tube density while S. solea favored the high tube density. Different water velocities showed an effect on the habitat preference of both organisms, for C. crangon there was a trend suggesting that the species avoids unstable or turbid water which is created at higher current velocities and low tube density. In contrast, habitat preference for S. solea was only affected by high water velocities where the fish chose to settle on the low tube density. At a low flow velocity, S. solea showed no preference to a particular density. Results show that the habitat preference of both species is independent of each other; there is no significant predator effect on the fish’ habitat preference. This experimental study examines the ability of L. conchilega tubes as potential refuge structures of epibenthic organisms. The results quantify an important ecosystem engineering function of L. conchilega reefs.

ISCED Categories

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0511 - Biology", "0521 - Ecology