Hostname: page-component-7c8c6479df-fqc5m Total loading time: 0 Render date: 2024-03-27T16:14:30.670Z Has data issue: false hasContentIssue false

Seasonal ‘fall out’ of sessile macro-fauna from submarine cliffs: quantification, causes and implications

Published online by Cambridge University Press:  08 January 2004

James J. Bell
Affiliation:
Department of Zoology and Animal Ecology, University College Cork, Lee Maltings, Co. Cork, Ireland University of Glamorgan, School of Applied Sciences, Pontypridd, Wales School of Animal and Microbial Sciences, University of Reading, Whiteknights, PO Box 228, Reading, RG6 6AJ, UK
David K.A. Barnes
Affiliation:
Department of Zoology and Animal Ecology, University College Cork, Lee Maltings, Co. Cork, Ireland British Antarctic Society, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
Claire Shaw
Affiliation:
Department of Zoology and Animal Ecology, University College Cork, Lee Maltings, Co. Cork, Ireland
Aine Heally
Affiliation:
Department of Zoology and Animal Ecology, University College Cork, Lee Maltings, Co. Cork, Ireland
Aisling Farrell
Affiliation:
Department of Zoology and Animal Ecology, University College Cork, Lee Maltings, Co. Cork, Ireland

Abstract

Submarine cliffs are typically crowded with sessile organisms, most of which are ultimately exported downwards. Here we report a 24 month study of benthic fauna dropping from such cliffs at sites of differing cliff angle and flow rates at Lough Hyne Marine Nature Reserve, Co. Cork, Ireland. The magnitude of ‘fall out’ material collected in capture nets was highly seasonal and composed of sessile and mobile elements. Sponges, ascidians, cnidarians, polychaetes, bryozoans and barnacles dominated the sessile forms. The remainder (mobile fauna) were scavengers and predators such as asteroid echinoderms, gastropod molluscs and malacostracan crustaceans. These were probably migrants targeting fallen sessile organisms. ‘Fall out’ material (including mobile forms) increased between May and August in both years. This increase in ‘fall out’ material was correlated with wrasse abundance at the cliffs (with a one month lag period). The activities of the wrasse on the cliffs (feeding, nest building and territory defence) were considered responsible for the majority of ‘fall out’ material, with natural mortality and the activity of other large mobile organisms (e.g. crustaceans) also being implicated. Current flow rate and cliff profile were important in amount of ‘fall out’ material collected. In low current situations export of fallen material was vertical, while both horizontal and vertical export was associated with moderate to high current environments. Higher ‘fall out’ was associated with overhanging than vertical cliff surfaces. The ‘fall out’ of marine organisms in low current situations is likely to provide an important source of nutrition in close proximity to the cliff, in an otherwise impoverished soft sediment habitat. However, in high current areas material will be exported some distance from the source, with final settlement again occurring in soft sediment habitats (as current speed decreases).

Type
Research Article
Copyright
2003 Marine Biological Association of the United Kingdom

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)