Sclerochronology in the Southern Ocean

Abstract

This manuscript aims to provide a comprehensive review of the work done by Antarctic sclerochronology research across different taxa (arthropods, bivalves, brachiopods, bryozoans, cephalopods, hard and soft corals, gastropods, echinoderms and teleost fish), provide an analysis of current challenges in the discipline and start a discussion of what sclerochronology can offer for Antarctic research in future. The Southern Ocean ecosystem remains largely unstudied in part for its remoteness, extreme climate and strong seasonality. This lack of knowledge, some of it even on basic biological information, it is especially worrying due to ongoing climate-driven changes that the Southern Ocean ecosystem is experiencing. Lack of long-term in situ instrumental series has also being a detriment to understand long-term feedbacks between the physical environment and the ecosystem. Sclerochronology, the study of periodic accretional patterns in the hard body structures of living organisms, has contributed to a wide range of Antarctic research disciplines (e.g. paleoclimate reconstructions, population structure analysis, environmental proxies). This review highlights a disparity in research focus by taxa with some groups (e.g. bivalves, teleost fish) attracting most of the research attention, whereas other groups (e.g. gastropod) have attracted much little research attention or in some cases it is almost non-existent (e.g. echinoderms). Some of the long-lived species considered in this review have the potential to provide the much-needed high-resolution eco-environmental proxy data and play an important role in blue carbon storage in the Sothern Ocean. Another issue identified was the lack of cross-validation between analytical techniques. Graphic abstract

Emerging biological archives can reveal ecological and climatic change in Antarctica

“…Live colonial animals (dark orange) (snow petrels, seals and penguins live for ~25 years or less), historic preserved animal colonies (light orange) are known from ~100,000 years ago. Benthic marine species (dark purple), (some Southern Ocean scleractinian coral species likely live for ~100 years (Roman Gonzalez, 2021 )). Fossilised benthic marine species (light purple), (fossil coral can be used for sclerochronological studies over 10,000s of years (Wilson et al, 2020 )).…”

“…Many Southern Ocean benthic taxa lack pelagic larval stages within their development, and several are slow growing (e.g., Barnes et al, 2006 ; Dahm & Brey, 1998 ) and long‐lived, (e.g., Burgess et al, 2010 ; Henry & Torres, 2013 ), features that contribute to their utility as archives (Figure 2b ; Table 2 ). The hard body structures (e.g., shell, corals) of Antarctic marine species that are laid down in periodic accretional patterns (growth rings) can reflect environmental drivers at the time they were deposited (see Roman Gonzalez ( 2021 ) and within). This technique relies on growth rings in individuals being deposited similarly across a population in response to common environmental drivers, and in some cases, growth rings can be annually or seasonally resolved (as is the case for ice cores) and absolutely dated (Peck & Brey, 1996 ).…”