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Deep Water Plants And Animals
by: Gary Larson, Oregon State University
with contributions by: H.
Phinney, D. McIntire, S. Loeb, M. Buktenica, N. Anderson, S. Earle
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Exploration of the bottom of Crater Lake in August 1988, using a
one-person submersible provided a unique opportunity to observe and
collect benthic fauna and flora directly off the lake bottom. Several
oligocheates were collected from the soft mud surface. One dive was
dedicated to exploring the caldera walls for moss (Drepanocladis)
and periphyton. Moss was observed at 253 meters (about 759 feet deep),
and a sample ws collected at a depth of 221 meters, or 663 feet. The
sample extended the known depth of the moss by about 100 meters, and
this is probably a world record depth. Periphyton ws observed on the
caldera walls to a depth of 147 meters, or 441 feet, but no samples were
collected.
The moss sample ranged in color from bright green through greenish
golden to a dark brownish red. The cells of the axes and "leaves" of
green axes exhibited numerous and prominent chloroplasts. The plastids
in plants that had aged and darkened were impossible to discern. The
cells of the darker leaves appeared to have reduce cell contents,
including reduced numbers of plastids. The leaves of the darkest axes
had usually lost their tips, and commonly, all of the lamina had eroded
except for the very base of the leaf. Three means of vegetative
reproduction were observed. No sexual or asexual reproduction was
observed.
The moss sample supported a rather uniform epiphytic flora as well
as some loosely entwined filaments. The latter consisted of and
unbranched green alga Rhizoclonium and a branched siphonaceous
alga Vaucheria (Xanthophyceae). The epiphytes were a filamentous
diatom Melosira and three species of green algae, two
Oedogonium species and a Bulbochaete. In addition, there
were a number of pennate diatoms attached to the primary leaves of the
moss and to a less extent to Rhizoclonium, Melosira, and
Vaucheria.
A sparse fauna was found in the moss sample. This included a single
tartigrade, two unidentified nematodes, two species fo rotifer, probably
Collotheca and Philodina, several species of ciliates,
including Strichotricha and Vorticella, and midge
larvae.
A rock was collected at 379 meters, or 1,137 feet deep, and was
examined in the laboratory, and a single living specimen of epilithic
algae was found. Although it was impossible to remove the speciment
from the rock, it was photographed and tentatively identified as
Tribonema. This appears to be a world record depth for epilithic
algae in fresh water.
The great depths at which plants were found living in the Lake is an
important discovery to the ten-year limnoligical assessment of Crater
Lake. Such growth is probably an integrated measure of water clarity.
Since small changes in turbidity could have substantial impacts on the
amount of available light at these great depths, documentation of the
floral assemblages and their depth distributions provide very importatn
baseline information for future monitoring of the clarity of Crater
Lake.
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