THE FIRST EXPERIENCE OF ASSESSING TAXONOMIC DIVERSITY, ABUNDANCE AND BIOMASS OF INVERTEBRATES (SPIDERS AND INSECTS) IN KAMCHATKA IN THE RIVER FLOODPLAIN BACKGROUND BIOTOPES (ON THE EXAMPLE OF THE AVACHA RIVER LOWER REACHES)

The parameters of the seasonal dynamics of taxonomic diversity, abundance (number) and biomass of invertebrates (insects and spiders) on 10 different in appearance test areas in the background terrestrial biotopes of the floodplain in the interfluve of the Avacha and Pinachevskaya Rivers in 2018 and 2020 were determined. The maximum indicators of invertebrates abundance (from 200 specimens to 1 thousand or more per oblique by entomological net) in different biotopes were observed at different periods, but all of them occured in the period from mid-June to mid-October, usually from mid-July to August. The absolute values are various in different biotopes. The invertebrates biomass usually grows continuously from May to July, peaks in late July or the first half of August and then declines to a minimum by November with the onset of frost and before the first snowfall. The maximum invertebrates biomass per 1 m2 (during the peak value for each biotope) in 2018 was 0.033 – 0.097 g / m2 (0.998 g – 2.9 g per mowing), the average value (n = 10) was 0.049 g / m2. This index was less in 2020. The average value of insect biomass for 2 seasons per conditional 1m2 of the river floodplain in the studied area was about 0.029 g. Insects predominate among invertebrates, but spiders also occupy a significant part: 18% in abundance (number) and 38% in biomass, respectively,according to the results of mowing in 2018.