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Folder Marine and Coastal Biodiversity

Brigita Laime, Faculty of Biology, University of Latvia

    Total length of Latvian seacoast reaches 496 km. The present seacoast is a relatively young formation (two to several thousand years) and has established after the retreat of the Litorina Sea. Of course, to a greater or smaller extent coastal habitats have developed under the influence of human activities (fishery, forestry, animal breeding and agriculture, military activities etc.). About 90 % from the coast are natural habitats; the rest are built up (ports, buildings) or changed in another way. In spite of that the Baltic Sea coast in Latvia characterise high species and natural habitat diversity. A short overview on the main habitat types is available in the Handbook of Latvian Habitats (Kabucis 2001).

Characteristic of seacoasts

Anda Ikauniece, Institute of Aquatic Ecology, University of Latvia

    The Baltic Sea distinguishes among the other salt water-basins due to its relatively low salinity that determines the number of species occurring there. There is a small number of water organism species that have adapted to life in slightly salty water. The marine area in Latvia includes two comparatively different ecosystems - the eastern part of the Baltic Sea and the Gulf of Rīga (excluding its northern part). The salinity in the Baltic Sea is higher (about 7 PSU - Practical salinity units)) than in the Gulf of Rīga (about 5 PSU). Therefore, higher species diversity is observed there.
    Both in the sea and gulf ecosystems two different habitat types are distinguished - coastal area and the open part. In the coastal part in the places with suitable substrate, like stones, benthic algal growths occur characterised by the highest biological diversity in the marine ecosystems. The growths serve as a spawning and a feeding area for fish. In the open part two coenosis, such as water (pelagic) and sea bottom (benthic) are distinguished. In the pelagic coenosis plankton groups are most important are, like phytoplankton (microscopic algae) and zooplankton (microscophic crusceans and other animals). Benthic coenosis represent animals living in the ground (zoobentos).


    The largest threat to the ecosystem is eutrophication - the increase of nutrient concentration in the water inducing ecosystem change. Due to eutrophication in the growths of benthic algae the species structure changes - perennial algae are replaced by annual (Cladophora sp.) causing quality change of the whole habitat. With the decrease of water limpidity, depth range of algal distribution diminishes, as well as quantity of algae and also the ability of ecosystem self-purification. In the pelagic coenosis the eutrophication stimulates the massive development of phytoplankton and the change in the structure of zooplankton that is connected with the increase of the number of plant feeding species. Also in the benthos coenosis with the increase of digesting species number, the change of species structure takes place. In Latvian conditions it is one bivalve species, therefore the decrease of the species number and the dominance of one species is probable. With the increase of the die-off and sinking phytoplankton quantity, in the ground the oxygen condition becomes worse. With the start of oxygen deficiency, the total vanishing of the benthic coenosis is probable.

    Also the other human activities, like organization of port facilities without preliminary study of the environment, ground and waste dropping into the sea, non-adequate fishery intensity, oil product spills, can cause a threat to the ecosystem.

    In Latvia in the 70-ties and 80-ties of the 20th century the eutrophication impact on marine ecosystems was considerable. It is best documented for the Gulf of Rīga where the biomass of the phytoplankton and amount of zooplankton increased (directly increasing the number of plant feeding animals). Similarly, in the benthos coenosis the relation between animal groups changed firstly and increased the quantity of the digesting bivalve Macoma baltica. At the beginning of 90-ties an overall decrease of the number of benthic animals was observed and definite species (mainly amphipods) disappeared from separate parts of the Gulf of Rīga. Although from 1995 the state of the benthos coenosis gradually improved, in the central areas of the Gulf in 2000-2001 the number of benthic organisms was very small. In the 80-ties of the 20th century in the growth of benthic algae the decrease of the limit of the depth distribution and the dominance of annual algae was observed.
    Up to now the second largest threat to marine ecosystems oil product spills. At the beginning of 90-ties after the accident of tanker "Globe Asimi" in 1983 in the benthic algae coastal communities of the Baltic Sea a considerable decrease of growth area was observed.

Invasive species in marine ecosystem

Although in the area of the Baltic Sea several tenth of invasive species are observed, the consequences of their invasion is difficult to follow due to the lack of information about the ecosystem state before the arrival of these species. Therefore, the influence of invasive species can be evaluated only for two of them that have appeared during the last 15 years - for the benthic worm Marenzelleria viridis and zooplankton cladoceran Cercopagis pengoi. The species are well adapted to the life in Latvian marine waters although there is a lack of a thorough information about their influence on environment. There is a possibility that M. viridis conquers with the local benthic worm species. An unpleasant, although economical phenomenon that concerns C. pengoi was observed - during the summer period the species individuals piled in the fishing nets damaging them slightly and diminishing the catch amounts. 

Complete species list and figures can be obtained in the data basis of the Baltic Sea invasive species.


Governmental institutions

Scientific institutions


The general regulations and laws concern all the marine area but there is no one management strategy.


    At present marine ecosystem management is more orientated to the coastal area and directly available nature resources, such as fish, marine ground sediments. The National Programme on Biological Diversity (2000) involves a special part devoted to the protection of marine biodiversity. Most of the activities needed for the marine diversity protection are connected with diminishing general marine pollution and eutrophication. The action plan for the concrete activities is not well elaborated. The main attention is paid to the questions subordinated to the biological diversity, like environment protection in the ports and oil pollution control.

    In the frame of Helsinki Commission Latvia has nominated 4 marine areas as the Baltic Sea Protected Areas. Biological diversity is one of the reasons for their choice. Although 3 of them are included in the presently protected nature areas: North Vidzeme Biosphere Reserve, Slītere National Park and Engure Nature Park, the actual protection and management of the are is lacking.
Also in the Important Bird Areas (IBA) located in the coastal area no real protection is carried out.

    Seacoast is protected for more than 150 years. In different times the width of the protected zone has changed between 100 to 300 metres. At present is 300 metres wide protection zone where restrictions for building, forest use and other activities are set. To protect the nature values of the coastal zone in separate places specially protected nature areas are established. The length of these areas are about 232 km near the sea (Laime 2000). The present functional zones of protected nature areas and the corresponding general protection regulations are little orientated to the protection of seacoast habitats and species maintenance. For most of the part of protected nature areas protected landscape area is characteristic or neutral regimen that has little restrictions which would favour the conservation of nature diversity. Only 34 % from the protected coast length concern nature reserves. Most of the coastal habitats belong to those protected in Europe (Anon.1996; Kabucis 2000).



The Programme "Marine Environment Monitoring" is carried out by Institute of the Aquatic Ecology of the University of Latvia, Division of Sea monitoring (phone 7614840, fax 7601995, e-mail: juris[at] The Programme includes regular monitoring of abiotic environment factors, like water temperature, salinity, chemical compounds, oil and heavy metal concentrations in different matrixes and biological parameters, such as (phytoplankton, zooplankton, zoobentos, phytobentos) in the Sea area of Latvia through the year. Every year Report on the ecosystem status is handed in the Latvian Environmental Agency.

At the moment in the discussion phase is the Marine Biodiversity Monitoring Programme elaborated at the end of 2001 (has an access in Latvian Environmental Agency - web page) that includes sea bird, fish and sea monitoring as well as includes close co-operation with the Marine Environment Monitoring Programme. It is planned to realise the marine environment monitoring jointly with the Institute of Biology, University of Latvia, Latvian Fisheries Research Institute and Institute of the Aquatic Ecology of the University of Latvia.

Existing researches

Projects carried out by the Institute of Aquatic Ecology, University of Latvia in 2000 - 2002:

  • Andrusaitis A. Investigation of the Pelagic-Benthic Interaction in the Open Part of the Gulf of Rīga.
  • Balode M. The Role of Environmental Factors on the Bloom of Potentially Toxic Phytoplankton and Production of Algal Toxins.
  • Boikova E. Seasonal Processes and Mechanisms in the Turnover of Biotic Material
    in the Gulf of Rīga.
  • Additional information about the projects is available in the web page of the Latvian Council of Science



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Folder Charasteristic of the seacoast