Makrozobentoso bendrijų struktūra ir pasiskirstymas naujai susiformavusiame lagūnoje atsitraukiančio ledyno zonoje, Svalbarde
Kormilicina, Aleksandra |
Šio darbo tikslas buvo nustatyti makrozoobentoso bendrijų struktūrą bei jų pasiskirstymą besitraukiančio ledyno pakraštyje Svalbarde, Europos Arkties regione. Darbo metu, naujai besiformuojančioje lagūnoje, Eidembuktoje surinkti 52 mėginiai iš kurių, pasitelkus Arkties floros ir faunos taksonomijos ekspertų pagalbą, buvo identifikuoti 7 makrozoobentoso rūšys arba aukštesnio rango taksonai. Pagal nustatytus fiziko-cheminius aplinkos parametrus (gylį, temperatūrą, druskingumą, deguonies kiekį ir drumstumą) šiame darbe buvo vertinama jų reikšmė makrozoobentoso bendrijų pasiskirstymui įvairiuose lagūnos gyliuose, siekiant nustatyti, kurie veiksniai statistiškai reikšmingai įtakoja skirtingų bendrijų formavimąsi. Gauti rezultatai parodė, jog tyrimo metu identifikuotos šios makrozoobentoso rūšys: Oligochaeta undet., Chironomidae gen. sp., Gammarus sp., Yoldiella intermedia, Harmothoe impar, Mysis oculata ir Ostracoda undet. Visos šios rūšys būdingos Arkties regionui ir aptinkamos įvairiose Svalbardo ekosistemose – nuo lagūnų iki upių ir pakrančių. Didžiausią ekologinį sutinkamumą tyrime turėjo Y. intermedia ir M. oculata, rūšys. Centrinėje lagūnos dalyje (10–30 m gylis) dominavo Y. intermedia bendrija (3 ± 11 ind. m-2; 0,03 ± 0,10 g m-2), litoralėje – Mysis oculata (3 ± 9 ind. m-2; 0,03 ± 0,11 g m-2), o vakarinėje, rytinėje ir šiaurinėje seklių vandenų zonoje – Chironomidae gen. sp. bendrija (4 ± 14 ind. m-2; 0,003 ± 0,014 g m-2). Y. intermedia gausumui reikšmingi veiksniai – gylis, druskingumas, temperatūra ir deguonis; M. oculata – temperatūra, deguonis, drumstumas, gylis; Chironomidae gen. sp. – temperatūra, deguonis, gylis ir druskingumas.
The Svalbard archipelago, in the Northern Hemisphere, is one of the fastest-warming regions. The temperature increases are especially high in northern Svalbard, where the average winter temperature increases by as much as 2°C per decade. This research aims to investigate the fresh water lagoon being formed due to the retreat of the Svalbard glacier. New observation shows that the retreating glacier is exposing bodies of water that previously were hidden and have distinctive chemical and physical properties. The water that drains from the glacier into the lagoon is in part mingled with seawater and creates density stratified flows. This not only creates new water bodies but also large amounts of organic materials along with fresh water are brought into these stripped regions. These factors in addition to other physical factors control the water structure and circulation as well as the primary productivity and the nature of the sediments. The Arctic glacier retreats transforms the coastline and ocean morphology which changes the land and water life forms, and creates new zones for aquatic life. The structure of benthic communities is strongly influenced by physical and chemical factors, especially in newly forming water bodies. The study examines the process of lagoon formation in Svalbard, which expands and supplements its territory with new elements each year. This is important not only for scientific purposes but also from a practical standpoint because little is known about the inhabitants of the benthic fauna in these areas or the existing communities. The aim of the study is to determine the structure of macrozoobenthic communities and their distribution along the retreating glacier margin in Svalbard. The methodology involves collecting samples from different parts of the lagoon, analyzing them in the laboratory, including live identification, biomass determination, and community structure analysis. Environmental physical and chemical parameter analysis will also be conducted, along with determining their influence on community distribution. During the study, 7 macrozoobenthos species or higher taxa were detected in the Eidemlaguna samples: Yoldiella intermedia, Harmothoe impar, Mysis oculata, Gammarus undet., Chironomidae gen. sp., Oligochaeta undet. and Ostracoda undet. In the sublittoral, the mean abundance of macrozoobenthos in 2022 was (5 ± 9 ind. m-2), with a biomass of (0,10 ± 0,60 g m-2); in 2023 the mean abundance was found to be (9 ± 30 ind. m-2), with a biomass of (0,02 ± 0,04 g m-2). In 2024 the abundance was found to be (37 ± 61 ind. m-2) with a biomass of (0,38 ± 0,82 g m-2). In the littoral, invertebrates have a mean abundance of (21 ± 20 ind. m-2) and biomass of (0,13 ± 0,16 g m-2). Three macrozoobenthos communities were identified: the bivalve Y. intermedia community in the central part of the lagoon in the sublittoral (3 ± 11 ind. m-2; 0,03 ± 0,10 g m-2); the mysid Mysis oculata community in the littoral part of the lagoon in all parts of the lagoon (3 ± 9 ind. m-2; 0,03 ± 0,11 g m-2); the community of Chironomidae gen. sp. in the western, eastern and northern parts of the lagoon littoral (mean abundance 4 ± 14 ind. m-2; biomass 0,003 ± 0,014 g m-2). The abundance of Y. intermedia was positively influenced by depth and salinity, and negatively influenced by temperature and oxygen content. M. oculata abundance increased with increasing temperature, turbidity and oxygen content, but decreased with increasing depth, while Chironomidae gen. sp. abundance was positively correlated with temperature and oxygen content, and negatively correlated with depth and salinity. The final results will help understand how climate change affects Arctic benthic communities and how retreating glaciers change environmental structure and biological diversity in newly forming water bodies.