TY - JOUR
T1 - Megabenthic standing stocks and organic carbon demand in a warming Arctic
AU - Mazurkiewicz, Mikołaj
AU - Meyer-Kaiser, Kirstin
AU - Sweetman, Andrew K.
AU - Renaud, Paul E.
AU - Włodarska–Kowalczuk, Maria
N1 - Funding Information:
We are grateful to the captain and crew of the R/V Helmer Hanssen, and to Jørgen Berge for technical support. Financing was provided by the University Centre in Svalbard and Akvaplan-niva (to PER), by the National Science Centre grant number UMO-2016/23/B/NZ8/02410 (AbeFun), and statutory funds of the Institute of Oceanology, Polish Academy of Sciences (to MWK).
Publisher Copyright:
© 2021 The Author(s)
PY - 2021/8
Y1 - 2021/8
N2 - Benthic megafauna (organisms large enough to be visible on seabed photographs) are regarded as important for carbon cycling in benthic habitats. They are a food source for many predators like fish and marine mammals and may stimulate carbon mineralization in sediment by bioturbation. However, few studies address these basic characteristics of megabenthos quantitatively. This study quantifies the spatial variability in standing stock (biomass) and functioning (secondary production, respiration and carbon demand) of benthic megafauna in fjords and on the continental shelf of Svalbard. Organisms were measured from sea bottom images to assess their biomass using length-weight relationships and volumetric methods, then respiration and production were estimated with empirical artificial neural network models. Significantly higher standing stock, secondary production, respiration, and carbon demand were found in fjords categorized as ‘cold’ (as defined by water temperature, prevailing water masses and ice-cover) than in the ‘warm’ ones. Cold fjords were dominated by Echinodermata, while in warm fjords Crustacea prevailed. All megafaunal community parameters were negatively correlated with bottom temperature. It was not possible to assess specific direct impacts of temperature, and indirect effects may be more relevant to our findings. These include temperature-driven changes in primary production, ice cover and ice-algae production or predation pressure from carnivores expanding their ranges northward. The progression of climate warming may affect megafaunal communities by reducing their biomass, production, and carbon demand and have profound effects on ecosystem functioning.
AB - Benthic megafauna (organisms large enough to be visible on seabed photographs) are regarded as important for carbon cycling in benthic habitats. They are a food source for many predators like fish and marine mammals and may stimulate carbon mineralization in sediment by bioturbation. However, few studies address these basic characteristics of megabenthos quantitatively. This study quantifies the spatial variability in standing stock (biomass) and functioning (secondary production, respiration and carbon demand) of benthic megafauna in fjords and on the continental shelf of Svalbard. Organisms were measured from sea bottom images to assess their biomass using length-weight relationships and volumetric methods, then respiration and production were estimated with empirical artificial neural network models. Significantly higher standing stock, secondary production, respiration, and carbon demand were found in fjords categorized as ‘cold’ (as defined by water temperature, prevailing water masses and ice-cover) than in the ‘warm’ ones. Cold fjords were dominated by Echinodermata, while in warm fjords Crustacea prevailed. All megafaunal community parameters were negatively correlated with bottom temperature. It was not possible to assess specific direct impacts of temperature, and indirect effects may be more relevant to our findings. These include temperature-driven changes in primary production, ice cover and ice-algae production or predation pressure from carnivores expanding their ranges northward. The progression of climate warming may affect megafaunal communities by reducing their biomass, production, and carbon demand and have profound effects on ecosystem functioning.
KW - Benthos
KW - Respiration
KW - Seabed photography
KW - Secondary production
KW - Svalbard
UR - http://www.scopus.com/inward/record.url?scp=85108726420&partnerID=8YFLogxK
U2 - 10.1016/j.pocean.2021.102616
DO - 10.1016/j.pocean.2021.102616
M3 - Article
SN - 0079-6611
VL - 196
JO - Progress in Oceanography
JF - Progress in Oceanography
M1 - 102616
ER -