The species compositions and densities of the littoral and pelagic zooplankton
assemblages in Crater Lake were compared. The littoral and pelagic zooplankton
assemblages of most lakes are typically different due to different habitat conditions in the
two zones. The littoral zone of Crater Lake lacks many of the habitat characteristics,
which distinguish a typical littoral zone from the pelagic zone. In fact, none of the water
quality variables measured differed significantly between the littoral zone and epilimnion
of the pelagic zone in Crater Lake.
The littoral and pelagic zones of Crater Lake were sampled with twelve paired
sites in August and again in September of 1995. For the purposes of this study, the
littoral zone was defined as lakeward from the shoreline to the 10m depth contour. At
each paired site the pelagic assemblage was sampled to a depth of 120m at the 200m
depth contour.
Despite the almost identical water quality between the pelagic and littoral zones of
Crater Lake, lack of vascular macrophytes in the littoral zone, and well-mixed
epilimnion, the littoral zooplankton assemblage differed from the pelagic assemblage in
both species composition and density. Several ubiquitous zooplankton taxa dominated
both the littoral and pelagic zooplankton assemblages, although the density of these taxa
as well as the relative abundance of these taxa differed between zones. These ubiquitous
species reached their maximum densities in the metalimnion of the pelagic zone at a
depth range of 10 to 60 meters below the lake surface and were considered primarily
pelagic. A shift in wind direction between sampling periods influenced the distribution of
pelagic zooplankton taxa in the littoral zone. Twenty-four taxa were recorded in the
littoral zone, and aside from infrequent exceptions, none of these taxa were found in the
pelagic zooplankton assemblage. Most of the littoral taxa were primarily adapted to the
benthic zone. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33634 |
| Date | 29 May 1998 |
| Creators | Warncke, William Madara |
| Contributors | Larson, Gary L. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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