Two separate studies on the distribution of gammarid amphipods
in the bathyal and abyssal benthic environments demonstrated that
different assemblages could be found at a single depth over distances on
the order of 100 kilometers. These studies evaluated changes in the
species composition and relative abundance of the amphipod assemblage
utilizing samples collected with an epibenthic sled.
The amphipod faunas of the San Diego Trough and Tanner Basin
were compared utilizing 18 epibenthic sled hauls. These two bathyal
basins of the Continental Borderland off Southern California are very
similar in their environments and both have a bottom depth close to
1250 meters. The amphipod fauna from each basin was characterized
by comparing the percentage each species comprised of the total
amphipod fauna, the frequency of occurrence of each species, and the
rank order of abundance of species. The large differences observed
in the structure of the amphipod assemblage between the two basins
can probably be attributed to different sources of food in the two basins.
Nineteen sled hauls were collected at two stations on Cascadia
Abyssal Plain located off the Oregon coast at 2800 meters depth. The
two stations were representative of the near shore and offshore portions
of this abyssal plain. The amphipod assemblages were found to
be very different at these two stations, despite their similar depths
and physical environments. Geological evidence indicated that the
sources of food to the sea floor at these two stations were likely to be
very different. It was this difference in food input that seemed most
likely to be the cause of the faunal difference.
These studies of "mesoscale" zoogeography have added a new
element of complexity to our understanding of factors controlling
animal distributions in the deep sea benthos, because they have demonstrated
that different assemblages can be found at the same depth
in the same geographic region. The results suggest that the quality
and quantity of food supplied to the deep sea floor may play a major
role in controlling the composition of the fauna. / Graduation date: 1977
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/30331 |
| Date | 07 June 1976 |
| Creators | Dickinson, John J. (John Joseph), 1946- |
| Contributors | Carey, Andrew G. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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