Do monk seals exert top-down pressure in subphotic ecosystems?
Article first published online: 22 OCT 2008
No claim to original US government works
Marine Mammal Science
Volume 25, Issue 1, pages 91–106, January 2009
How to Cite
Parrish, F. A. (2009), Do monk seals exert top-down pressure in subphotic ecosystems?. Marine Mammal Science, 25: 91–106. doi: 10.1111/j.1748-7692.2008.00245.x
- Issue published online: 12 JAN 2009
- Article first published online: 22 OCT 2008
- Received: 12 September 2007Accepted: 7 July 2008
- deep water;
- marine fish;
- monk seals;
- Monachus schauinslandi;
- predator control
Patterns of subphotic fish assemblages on seamounts in the Northwestern Hawaiian Islands were identified and compared for potential structuring influences, including the bottom-up effects of regional oceanic productivity and top-down predation pressure exerted by visiting monk seals (Monachus schauinslandi). Patterns in fish size, density, and biomass were evaluated at the deep extreme (350–500 m) of the seals feeding range to avoid confounding effects of diverse shallow habitats (e.g., coral reefs). Fish number and size were used to calculate biomass density of the seamount fish assemblages that were then compared to the independent variables of summit depth, substrate type, relief, oceanic productivity, distance to seal colonies, and seal colony population. Only the variables of distance to seal colony and seal colony population were retained in a multiple regression model that explained 31% of the variance. Despite the presence of obvious regional differences in oceanic productivity, the overall patterns in the subphotic fish assemblages are better explained by the top-down hypothesis of predation pressure from monk seals.