Abstract
Glacier retreat is a major long-standing global issue; however, the ecological impacts of such retreats on marine organisms remain unanswered. Here, we examined changes to the polar benthic community structure of “diatoms” under current global warming in a recently retreated glacial area of Marian Cove, Antarctica. The environments and spatiotemporal assemblages of benthic diatoms surveyed in 2018–2019 significantly varied between the intertidal (tidal height of 2.5 m) and subtidal zone (10 and 30 m). A distinct floral distribution along the cove (~ 4.5 km) was characterized by the adaptive strategy of species present, with chain-forming species predominating near the glacier. The predominant chain-forming diatoms, such as Fragilaria striatula and Paralia sp., are widely distributed in the innermost cove over years, indicating sensitive responses of benthic species to the fast-evolving polar environment. The site-specific and substrate-dependent distributions of certain indicator species (e.g., F. striatula, Navicula glaciei, Cocconeis cf. pinnata) generally reflected such shifts in the benthic community. Our review revealed that the inner glacier region reflected trophic association, featured with higher diversity, abundance, and biomass of benthic diatoms and macrofauna. Overall, the polar benthic community shift observed along the cove generally represented changing environmental conditions, (in)directly linked to ice-melting due to the recent glacier retreat.
Highlights
The climate crisis is highlighted by the breaking of temperature records during the austral summer in the Antarctic continent especially in West A ntarctica[1], and the ecological impacts of these changes becoming increasingly serious[2,3]
To identify terrestrial influence on the cove, concentrations of δ13C and δ15N in the particulate organic matter (POM) of seawater and benthic diatoms were measured along the cove (B2, B4–B6; insufficient samples were available for B1 and B3)
The occurrence, distribution, and signature taxa of benthic diatoms found in Marian Cove, West Antarctica, broadly demonstrated a series of ecological responses, from early colonization, to community development, diversified and enriched
Summary
The climate crisis is highlighted by the breaking of temperature records during the austral summer in the Antarctic continent especially in West A ntarctica[1], and the ecological impacts of these changes becoming increasingly serious[2,3]. Glacier retreat together with ice-melt in the fjords of West Antarctica is expected to affect benthic microflora, leading to blooms of seabed diatoms[5]. Diatoms are important primary producers in Antarctica[6], and are used as biological indicators of the rapidly changing environment, such as global w arming[7,8]. Despite their ecological significance in the coastal waters of Antarctica, response of polar benthic diatoms to glacier retreat remains limited understanding. We examined changes to the polar benthic community structure of diatoms under current global warming in a recently retreated glacial area of Marian Cove, West Antarctica (Fig. 1). The results of the current study are expected to provide reference data on how the retreat of glaciers is affecting marine ecosystems in the rapidly changing and harsh environment of the polar region
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