642 / 2024-09-18 19:18:57

Nutrients fluxes with rivers runoff and response of receiving basins ecosystems on both sides of the Kamchatka Peninsula

river runoff,nutrients,carbon,coastal ecosystem,Kamchatka,volcanism

Identification of the main sources of nutrients is a key direction for understanding the functioning of coastal ecosystems of Kamchatka with high primary production that are feeding background for bowhead and gray whales. This study compares the nutrient fluxes of the Kamchatka River and Penzhina River in the East and the Northwestern of the Kamchatka, which have very similar water runoff and are practically not inhabited by people. The Kamchatka River, unlike the Penzhina River, drains volcanic territories, including the areas of the most active volcanoes of the Klyuchi group and Shiveluch volcano. On April 11, 2023, the largest eruption of the Shiveluch volcano occurred, covering the river valley with ash. Thus, it became possible to obtain contrasting results on the chemistry of the river flux of the Kamchatka River with and compare them with the Penzhina River. The Penzhina River had DIP and DIN concentrations in different seasons near the mouth of 0.2 – 0.8 and 0.17 – 0.35 µM, respectively. While the Kamchatka River had DIP and DIN concentrations in different seasons near the mouth of 2.79 – 3.87 and 10.0 – 23.8 µM, respectively. It has been established that volcanoes form high concentrations of nutrients in the catchment area of the Kamchatka River. According to the data obtained, the biomass of zooplankton in Penzhina Bay was at the level of 100 mg/l, while in Kamchatka Bay it exceeded 2000 mg/l. Thus, the biomass of zooplankton in the receiving basin, which is influenced by the runoff of the Kamchatka River with a volcanic catchment area in Eastern Kamchatka, is 20 times higher than in the basin, which has a small flux of nutrients with the river runoff in Northwestern Kamchatka. This study demonstrates the connection between volcanism in the catchment area and the formation of high zooplankton biomass in the coastal area through nutrient fluxes with river runoff.

The work was carried out with the financial support of the Russian Science Foundation 23-77-10001