Impact of the bird-manure caused eutrophication on the abundance and diversity of chironomid larvae ( Diptera ; Chironomidae ) in lakes of the Bolshoy Aynov Island ( Russia , Barents Sea )

We report on the perceived impact of bird faeces as an agent of organic matter transfer on the density and species richness of the Chironomidae in the lakes of the Bolshoy Aynov island (Barents Sea, Northern Russia). In total we recorded 15 species of Chironomidae. Highest species richness and specimen numbers were recorded in Lake Severnoe, closest to the large bird colony. Introduction Sea bird manure is an important source of nutrient transfer from aquatic ecosystems to terrestrial (Ellis et al. 2006). It is well known that removal of phosphorus and nitrogen from marine environments to terrestrial contributes to soil formation on the isles. Influx of nutrients with bird manure is crucial to maintain productivity of the northern aquatic systems, which are normally oligotrophic or dystrophic. Bird manure is also important for the formation of ornithogenic soils and waters (Tatur 2002). In some areas, like the maritime Antarctic, high Arctic and northern Europe, such ornithogenic landscapes are common and important for the functioning of the coastal and inland freshwater ecosystems (Tatur 2002). In this short communication, we will examine the Chironomidae communities in several small lakes of the Bolshoi Ainu Island in the secluded Ainu archipelago in the Barents Sea, close to Murmansk, Russia. This island is an important sea bird sanctuary, inhabited by large colonies of puffins, cormorants and little gulls (Khleboslov et al. 2005); thus, we hypothesized that this site would be a suitable place to study possible bird colonies impact on freshwater Chironomidae species richness and density. Materials and Methods Bolshoy Aynov Island is in the eastern part of Varangerfjord, Barents Sea (Russia). The island is about two kilometers long and about one and a half kilometers wide. The landscape is mainly flat (Fig 1). The vegetation is typical for the southern tundra. The climate of the Island is warmer than the climate of the adjacent coast of the Kola Peninsula because it is heated by the North Atlantic Current. The Bolshoy Aynov Island is protected and included in the Kandalaksha State Nature Reserve. The island has five small lakes (about 5-20 meters length) and one relatively large lake (more than 100 meters in length). The material was collected on seven sites from four small lakes of Bolshoy Aynov Island. All the samples were collected by using a hand-net with mesh size 1000 μm during mollusc collection, thus, due to the inappropriate mesh-size, smaller specimens probably were lost. Samples were preserved in formaldehyde. The samples were sorted by hand using an MBS-10 dissecting microscope with x56 magnification. The site descriptions are given in table 1. Lake name Substratum Depth, cm Maloe (Site 1) Silt with dead vegetation 40-50 Maloe (Site 2) Dead organic matter, living Fontinalis sp. and algae 50 Maloe (Site 3) Fontinalis sp. 60-70 Srednee Dead organic matter 70 Severnoe (Site 1) Silt, dead organic matter 15 Severnoe (Site 2) Silt, dead organic matter 120 Zapadnoe (Site 1) Silt, dead organic matter, sand 40 Table 1. Characteristic of the collection sites.


Introduction
Sea bird manure is an important source of nutrient transfer from aquatic ecosystems to terrestrial (Ellis et al. 2006).It is well known that removal of phosphorus and nitrogen from marine environments to terrestrial contributes to soil formation on the isles.Influx of nutrients with bird manure is crucial to maintain productivity of the northern aquatic systems, which are normally oligotrophic or dystrophic.Bird manure is also important for the formation of ornithogenic soils and waters (Tatur 2002).In some areas, like the maritime Antarctic, high Arctic and northern Europe, such ornithogenic landscapes are common and important for the functioning of the coastal and inland freshwater ecosystems (Tatur 2002).In this short communication, we will examine the Chironomidae communities in several small lakes of the Bolshoi Ainu Island in the secluded Ainu archipelago in the Barents Sea, close to Murmansk, Russia.This island is an important sea bird sanctuary, inhabited by large colonies of puffins, cormorants and little gulls (Khleboslov et al. 2005); thus, we hypothesized that this site would be a suitable place to study possible bird colonies impact on freshwater Chironomidae species richness and density.

Materials and Methods
Bolshoy Aynov Island is in the eastern part of Varangerfjord, Barents Sea (Russia).The island is about two kilometers long and about one and a half kilometers wide.The landscape is mainly flat (Fig 1).The vegetation is typical for the southern tundra.The climate of the Island is warmer than the climate of the adjacent coast of the Kola Peninsula because it is heated by the North Atlantic Current.The Bolshoy Aynov Island is protected and included in the Kandalaksha State Nature Reserve.The island has five small lakes (about 5-20 meters length) and one relatively large lake (more than 100 meters in length).
The material was collected on seven sites from four small lakes of Bolshoy Aynov Island.All the samples were collected by using a hand-net with mesh size 1000 µm during mollusc collection, thus, due to the inappropriate mesh-size, smaller specimens probably were lost.Samples were preserved in formaldehyde.The samples were sorted by hand using an MBS-10 dissecting microscope with x56 magnification.The site descriptions are given in table  The morphological terms are according to Saether (1980).Larvae were identified using the following keys: Pankratova 1970, 1977, 1983and Epler et al. 2013.

Results
Seven sampled sites yielded 15 species of Chironomidae larvae, belonging to three subfamilies (Table 2).Among them two species of Tanypodinae, nine species of Chironominae and four species of Orthocladiinae.
Highest species richness of eleven species was recorded for Lake Severnoe, while other lakes have richness of one-five species.Species of the subfamily Orthocladiinae were only recorded on the near-shore site of Lake Severnoe.Highest specimen density was recorded on the second site of Lake Severnoe, with the water depth 1.2 meters.This site was characterized by high numbers of Glyptotendipes paripes and Procladius sp.

Discussion
Among all the lakes sampled, Lake Severnoe was remarkably different in terms of chironomid species richness and diversity.This difference was probably caused by the proximity of a colony of marine birds, mainly puffin (Fratercula arctica (Linnaeus, 1758)) and cormorant (Phalacrocorax carbo (Linnaeus, 1758)).Nutrients from the faeces deposited in this colony are often washed away by the rains into the nearby Severnoe lake.In this lake a number of the species are traditionally associated with high nutrient load (Procladius sp., Chironomus sp.); there were also numerous phytophagous species (Cricotopus sp., Glyptotendipes paripes (Edwards, 1929), Psectrocladius obvius (Walker, 1856)) (Epler et al. 2013).We hypothesize that the higher species richness and specimen numbers of the Chironomidae larvae in Lake Severnoe were promoted by increased organic enrichment leached from bird faeces.The other lakes were further away from bird colonies, resulting in a lower influx of ornithogenic nutrients.Further research into the matter is required in order to assess the impact of the organic matter transfer by birds from the sea into the freshwater ecosystems.

Figure 1 .
Figure 1.Landscape of the Greater Ainu Island.

Table 1 .
1. Characteristic of the collection sites.