Ecological Assessment of Lake Baikal near the Settlement of Bol’shye Koty
Participants
Elena Lavrentieva (Russia—Buryat Republic)
Marilyn Phelps (U.S.A.—Minnesota)
Oksana Pugach (Russia—Irkutsk)
Tatiana
Serykh (Russia—Moscow)
Maxim Shapirov (Russia—Buryat Republic)
Leaders
Maxim Timofeyev
Zhanna Shatilina
Kuzma Kirichenko
Overview
Lake Baikal in eastern
Siberia, Russia, has six characteristics that combined make it a very unique
and worthwhile subject of study. Baikal
has (1) a wide diversity of species; (2) a high level of endemism among its
species; (3) a lack of mixing of its species with the species surrounding it in
Eastern Siberia; (4) development of fauna in the lake’s deep depressions; (5)
the presence of giant and dwarf forms of the same organisms; and (6) the
relatively rapid evolution within the lake.
There are 2500 species of animals and 1500 species of plants found in
Lake Baikal. Of the fauna, 85% of the
species are endemic, while 40% of the floral species are endemic. Further, the lake is unique even among the
large ultra-deep rift-formed lakes (such as Lake Tanganyika). Baikal is fully saturated in oxygen down to
its deepest depths. The oxygen mixing
throughout is due to currents caused by the inflowing rivers and exacerbated by
lake storms. These currents combine
with currents caused by the earlier freeze of the northern part of the lake and
the resultant temperature gradient forces more mixing. The high level of oxygen removes oxygen
level as a limit to growth.
Some scientists have
claimed that Lake Baikal is so resilient that the small human settlements along
its shore have no impact on the ecology of the lake. The monitoring study we completed was an attempt to evaluate the
accuracy of this assertion in the littoral zone of Lake Baikal, in the
Southwest portion of the lake. The littoral zone (also called the intertidal
area) is where the land and sea meet, between the high and low tide zones.
Monitoring of the bottom (benthic zone) of Lake Baikal has been conducted over the whole lake for the past fifty years. Monitoring of the pelagic and shelf zones has received considerably less attention. It is estimated that up to 70% of the species in Lake Baikal live in the top 20 meters. The littoral expanse from the shoreline for most of the lake is up to twenty meters followed by an abyss with many crevices.
Our area of focus was the Bol’shye Koty settlement, a two-hour hydroplane trip along the Angara River and Baikal from the city of Irkutsk, Russia. We took samples from a one cubic meter area from two separate project areas: one sample site was in the littoral zone near the shore directly adjacent to the center of the human settlement and near the outflow of the Bol’shye Koty creek; the other was in the Chornaya Bay, another area in the littoral shore zone north of Bol’shye Koty and further (approximately one kilometer) from human settlement.
Bol’shye Koty is a settlement of approximately sixty homes on the Southeastern shoreline of Lake Baikal north of the outflow of Baikal to the Angara River. The settlement has been populated since the seventeenth century, and has had a few noted anthropogenic environmental impacts, but similar to the other settlements along Baikal’s shores. Some actions in the region may also have impacts on the Lake, though adequate study has not yet been completed. For example, in 1982 a nuclear explosion was conducted underground in the Irkutsk region, reportedly not far from the lake, as an experiment to examine the meteorological effects and also to search for gas an oil reserves. More locally, the Bol’shye Koty river has been heavily managed and altered by human impact. In attempts to avert flooding, settlers have moved rocks lining the bottom of the river to the banks, causing channelization and increased speed of the stream. The stream is often seen filled with trash and products that may affect the water quality of the stream. The homes and hostels in the settlements are also making improvements such as flush toilets to attract more tourists to the area. The sewage produced is piped into the lake, not far from the shore. Many of the human impacts on the stream also make their way to Lake Baikal, but scientists have so far stated that the lake is resilient enough to handle current pollution inputs.
Part of the evidence supporting Lake Baikal’s resiliency has come from the action of the arthropods in the lake, which act as miniature filters, eating pollution and organic matter. The gammarids act as small scavengers, and researchers have found that they can smell decaying meat at a distance of one kilometer. Arthropods are found in a great variety of depths in the lake and contribute to the remarkable clarity – sixty meters in many areas. There are 270-280 species of arthropods in Lake Baikal and 60% are in the littoral zone. Thus the health of the gammarid populations is key to the clarity and resiliency of Lake Baikal.
Project
Design
We designed the
project with two main parameters. We
selected two sample sites – one close to Bol’shye Koty and one further away in
the Chornaya Bay. These sites were
chosen for their geographical similarity with the exception of the human
settlement at Bol’shye Koty. We
collected samples in the littoral zone throughout the day and night and
searched for six different groups of fauna: planaria, gammarid, nematodes,
heeralabedes (maggots), oligochaetes, and cottoid fish species. Within the gammarid (Crustacean) populations
we studied the specific species of Eulimnogammarus
verrucosus (Gerstfeldt, 1858), Eulimnogammarus
vittatus (Dybowsky, 1874),
Eulimnogammarus marituji Bazikalova (discovered 1945)[1], Eulimnogammarus cyaneus[2]
(Dybowsky, 1874) , Gmelinoides fasciatus (Stebbing, 1899),
and Pallasea gerstfeldtii/cancellus (we
did not distinguish between the species of Pallasea). Eulimnogammarus is the
youngest genus in the lake, and its species are known to exhibit the most rapid
evolutionary development.
We counted the numbers
of each species from each sample, weighed the biomass of each individual both
wet and dry (oven-dried for 60 minutes) and measured each individual’s
length. We also measured the
temperature, oxygen level and pH of the water for each sample. Our samples were
taken from August 4-August 15, 2003.
Results
Counting and measuring
the biomass of each species at each sample, we were able to determine the
dominant species both in biomass and in number. The most dominant group in biomass in the littoral zone near
Bol’shye Koty were the gammarids. Due
to storms, we failed to take a comparative sample in the littoral zone of the
Chornaya Bay. Still, gammarids were
the most dominant and important species to our work, and we were able to take
samples of gammarids from both Bol’shye Koty and Chornaya Bay for comparison.
Our most important
results came as we further compared the species to species dominance with the
gammarid population of each location.
We found that there was indeed a difference in species dominance in the
two locations. In Chornaya Bay where there is less anthropogenic
influence, we found the Eulimnogammarus
verucosus to be dominant both numerically and in biomass. In the Bol’shye Koty samples, Gmelinoides fasciatus was numerically
dominant, though not dominant in terms of biomass due to its small size.
Conclusion
and Recommendations
The gammarid species
dominant at the Bol’shye Koty location is one that is known to be comparatively
tolerant of anthropogenic impact, whereas the species dominant at the Chornaya
Bay site is more ecologically sensitive. This suggests that the environmental
impact of small settlements such as Bol’shye Koty does have an effect on the
littoral zone of Lake Baikal. We recommend conducting a more precise analysis
of how competition impacts population dynamics in both near-settlement and
settlement-free littoral zone areas.