Abyssal Fauna Associated With a Whale Fall in Monterey Canyon
- Robert Vrijenhoek
Monterey Bay Aquarium Research Institute
- Greg Rouse
The University of Adelaide, Australia
On Feb 6, 2002 using the ROV Tiburon, we discovered an unusual deep-sea community associated with the remarkably well-preserved carcass of a gray whale (Eschrichtius robustus) at 2,891 m depth in the axis of Monterey Canyon. The 9-10 m long carcass was found on the continental margin of northern California, approximately 31 km off shore, where it settled to the bottom on the canyon’s sedimented floor against the northern wall.
As a consequence, an intense burst of approximately 20,000 kg of organic material was exported to a typically food-depauperate sea floor. Particularly noteworthy was the absence of large scavengers, the presence of a number of opportunistic deep-sea species, and the abundance of unusual polychaetes, two of which actually digest bone and are new to science. Since the discovery, the whale fall has been visited on two additional occasions (in March and October 2002, at 1 and 8 months after discovery, respectively), allowing us to document faunal community changes in one of the deepest large food falls known to date.
An acoustic homer beacon was placed near the whale skull to facilitate relocation and planned monitoring of the site approximately 4 times per year for the next several years.
Summary to DateThe whale was identified as a juvenile gray whale - that likely died during the 18,000 km round trip migration route from the food-rich seas in the arctic to the breeding grounds of Baja California, Mexico Most deep-sea communities experience low food availability. Even in more productive regions like Monterey Bay, most deep-sea animals are adapted to an energy-limited existence. Some animals, however, can alter metabolism, growth rate, feeding behavior, and reproduction to exploit episodic pulses of organic enrichment, such as animal carcasses.
Such intense, discrete resource patches are thought to significantly influence to habitat complexity and biodiversity. Consequently a very unusual faunal assemblage was discovered in association with the whale fall - the most unusual animal was also the most dominant - a remarkable red-headed worm that live off of the bones themselves. We believe this animal has formed an unusual partnership with bacterial symbionts which it houses in unique structures that we call “roots”. The symbionts likely help the animal convert the decomposing whale lipids into energy.
The worm does not appear to possess a functional gut and, thus, relies almost certainly on these symbionts for nutrition. Even more strange, all of the adults are females - the males are actually dwarf parasites that hang onto the females with posterior hooks. They presumably hang onto the female until fertilization and release of the eggs. This type of reproduction is new to science.
The Monterey Bay whale fall is one of the deepest known whale falls discovered to date, and, thus, provides an opportunity to study localized effects of organic enrichment at depths as well as the unusual animals that ay rely exclusively on these very transient habitats.
Go to the MBARI website for more information on the new species of worms discovered during this study.
Unusual benthic fauna associated with a whale fall in
Monterey Canyon, California.
Goffredi, S.K., C.K. Paull, K. Fulton-Bennett, L.A. Hurrtado, R.C. Vrijenhoek. 2004. Deep-Sea Research 51:1295-1306
Osedax: Bone-Eating Marine Worms with Dwarf Males.
Rouse, G.W., S.K. Goffredi, R.C. Vrijenhoek. 2004. Science 305:668-671.
- Two new species of marine worms were discovered. These worms digest the bones of the whale.
- Over the first 8 months, bacterial mat coverage had increased and was still heaviest in sediments immediately adjacent to the carcass.
- Eight months after discovery, the underlying and adjacent sediments appeared very reduced and core samples smelled strongly of sulfide.
- During the past 20 months, the animal community associated with the whale fall has changed from a scavenging type community to invertebrates that rely directly or indirectly on the decomposition of the whale lipids for nutrition.
- Habitat association
- Dispersal & Recruitment
- canyon dynamics
Study MethodsWe use the ROV Tiburon to monitor the whale fall.
Figures and Images
Picture of the whale fall. Photo: MBARI
New species of bone devouring worm discovered during this study.
Map of the Monterey Bay showing the location of the whale fall (large white star) and the remains of seven other marine mammals (white circles).