Whaling Effects on Deep‐Sea Biodiversity

Abstract

Vast reductions in whale populations due to human hunting may have altered deep-sea biodiversity by redistributing and ultimately greatly diminishing an important source of organic matter and the stepping stones for chemosynthethic-based communities associated with hydrothermal vents and other regions of high organic input. The recent exciting discovery of Smith and colleagues (Smith et al. 1989; Smith 1992; Bennett et al. 1994), that decaying whale skeletons support a chemosynthetic-based deep-sea community similar to communities in hydrothermal vent and seep areas, indicates a greatly expanded role for falling whale bodies in creating and maintaining deep-sea biodiversity. Whaling represents one of the most dramatic alterations of mammalian species diversity by humans. It is difficult, however, to evaluate quantitatively the effects of whaling on deep-sea biodiversity because of the lack of historical or even good contemporary data on the size and distributions of most whale populations (Evans 1987) because the affected region is far removed from the disturbance source and because effects are being considered nearly a century after the fact. This marine example, however, does underscore the importance of thinking big and thinking to the long term in evaluating the potential effects of society's activities on nature. Organisms in the deep sea are highly food-limited and rely primarily on organic material falling from above (Grassle 1989). Large animal remains are quickly exploited by mobile local fauna (Dayton & Hessler 1972). These and other sources of concentrated, imported, organic matter-pulses of phytoplankton (Billet et al. 1983), drifting seaweed (Wolff 1979), and wood