Spatial variability of benthic macrofauna in the Ria of Vigo (NW Spain): Effect of sediment type and food availability

Abstract

The rias are incised and/or drowned river valleys with a high biological productivity dominated by estuarine circulation. This ecosystem provides diverse habitats due to spatial heterogeneity in physical and chemical conditions. The main objective of this study is to determine the structure and spatial distribution, both vertical and horizontal, of subtidal macrobenthic assemblages in relation to sediment type and food availability. A total of 12 sites belonging to 4 different soft-sediment localities in the Ria of Vigo (Spain) were sampled in order to reveal the relative importance of the environmental factors in controlling benthic fauna. The distribution of macrofauna communities was related to the type of sediment, which is linked to a wider set of environmental conditions, such as food availability and hydrodynamics. Multivariate analysis used to relate biochemical characteristics of the sediment and faunal parameters suggests that biopolymeric carbon fraction (BPC) and lipids are the best descriptors of sediment nutritional value, indicating the importance of food quality as a structuring factor in macrobenthic communities. This result suggests that the use of BPC and lipids as a proxy for benthic macrofauna quantitative changes and dynamics may be an effective tool in the study of soft-bottom benthic ecosystems.

Keywords:

• Benthic macrofauna
• food availability
• Ria of Vigo
• sediment characteristics
• subtidal
• vertical distribution

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We are grateful to S. Gil and R. C. de Dios for their invaluable help and enthusiasm in the field and in the lab and to J. Iglesias for map assistance. We thank the crew on the B/O Mytilus for technical assistance. Comments by C. Olabarria, the editorial office and one anonymous reviewer greatly improved this manuscript. Thanks are also due to Ian Emmett for language revision. This research was supported by the Regional Government of Galicia (Augas de Galicia and XUGA PGIDT02RMA30101PR). Funds to I. F. Rodil were provided in the course of a María Barbeito grant (Xunta de Galicia).

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark