PERIPHYTON MODEL COMMUNITIES
AS EARLY WARNING BIOINDICATORS OF CHANGES IN AQUATIC ECOSYSTEMS

Zolotarev Vladimir

Institute of Biology of Inland Waters of RAS,
152742 Borok, Yaroslavl region, Russia
å-mail: abin@mail.ru

Periphyton communities that are formed on artificial substrates can be defined as ⌠periphyton model communities■ (PMC). These communities are easily manipulated in the laboratory, and member species span the range of sensitivities of more familiar species. Microbial species are important members of attached communities in all ecosystems and play major roles in energy flow (Cairns, 2005). Their ability to rapidly colonize artificial substrates, cosmopolitan distribution, and other advantages, provide an assessment capability not generally available for higher organisms. In contrast to model ecosystems (microcosms) established in closed space, PMC develop in constant direct contact to the surrounding donor ecosystem. Microscale testing methods and the earliest pollution prevention are the most cost-effective (Wells, Lee, and Blaise, 1998).
Studies of microperiphyton were conducted in the lakes of Karelia, the Rybinsk reservoir, Lake Baikal, Lake Ladoga, the acidic lakes of Darwin National Park, the White Sea, the River Amur and in experimental microcosms/mesocosms. Protozoans are an important component of the periphyton communities of aquatic ecosystems. Abundances of unicellular organisms in most natural and artificial periphyton assemblages range from 100 to 100 000 cells per sq.cm and the number of species usually more than 150.
Periphyton biodiversity and relative abundance of ciliates and other protozoans can be used as indicators of toxic pollution and acidification. Multivariate statistics were used to design ⌠the scale of toxicity■ across a gradient of toxicant stress and organic compounds.
A new index of periphyton flagellates (IPF) as indicator of the trophic status of a water-body was developed:
IPF = Sa/Sv,
where Sa is a number of attached species, and Sv is a number of vagile species. The measurements of the numbers of flagellate species inhabiting submerged glass slides usually were made during the period of pioneer colonization till the maximum of choanoflagellates (first 1 or 2 weeks).
The results of a seasonal monitoring program carried out in five lakes of the Darwin national park revealed a close correlation (r - 0.823) between IPF on one side and dissolved organic matter on the other. Several advantages of utilizing PMC and the new indices for pollutional stress assessment are discussed (http://biomonitoring.narod.ru).
Since biota may differ essentially from one ecoregion to another, a universal biological monitoring system should use species with a cosmopolitan distribution. The diversity and abundance of protozoan species provide information about bacterial activity, hence protozoa are integral members of the decomposer community. This relationship, together with rapid reproductive rate and their intimate contact with the environment, make them more useful monitors of aquatic environments than the more frequently studied macroinvertebrates and fish (Bamforth 1982).
For the foreseeable future, with the development of on-line biosensors, a major application of microscale methods will be to predict, control and monitor anthropogenic changes in aquatic ecosystems, developing the new integrated standards, as ⌠Dow Jones■ for water quality. Our project "Automated Biomonitoring International Network (ABIN) √ strategic information system for benchmarking the health of aquatic ecosystems" - was included into the Projects Portfolio of the Priorities For Russia''s National Environmental Policy.

(Paper for the Conference)


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