Recent studies using acoustic techniques suggest that the biomass of mesopelagic fishes may be an order of magnitude higher than previously estimated from trawls. However, there is uncertainty surrounding these estimates, which are derived from shipboard echosounder measurements using necessary, but poorly constrained, assumptions. Here, an echosounder is used to measure individual target strengths at depth. These measurements are used to infer mesopelagic organism density through echo-counting. Measured target strengths are used to estimate organism density by inverting shipboard echosounder measurements. The two sampling methods agree well, but highlight the importance of accurate target strength measurements.
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http://dx.doi.org/10.1121/10.0003940 | DOI Listing |
Dokl Biol Sci
November 2024
Institute of Biology, Karelian Research Center, Russian Academy of Sciences, Petrozavodsk, Russia.
The contents of main classes of storage lipids (triacylglycerols, cholesterol esters, and waxes) in muscles and the liver of the beaked redfish Sebastes mentella were studied across the depth gradient and in different areas of the North Atlantic. Significant differences in storage lipid contents were observed between fish from different fishing horizons. The depth-dependent changes in lipids in fish tissues and organs were assumed to indicate that triacylglycerols (TAGs), cholesterol esters (CEs), and waxes are utilized as energy sources, in particular, to maintain the buoyancy during vertical migration.
View Article and Find Full Text PDFEnviron Microbiome
November 2024
Laboratory of Marine Organism Taxonomy and Phylogeny, Qingdao Key Laboratory of Marine Biodiversity and Conservation, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China.
Background: An increase in upper-ocean thermal stratification is being observed worldwide due to global warming. However, how ocean stratification affects the vertical profile of plankton communities remains unclear. Understanding this is crucial for assessing the broader implications of ocean stratification.
View Article and Find Full Text PDFEcol Lett
September 2024
MARBEC, University of Montpellier, CNRS, Ifremer, IRD, Sète, France.
Open Res Eur
August 2024
Marine Research Division, Basque Research and Technology Alliance (BRTA), AZTI Foundation Sukarrieta, Sukarrieta, Vizcaya, 48395, Spain.
Background: Siphonophores are diverse, globally distributed hydrozoans that play a central role in marine trophic webs worldwide. However, they still constitute an understudied fraction of the open ocean gelatinous taxa, mainly due to challenges related to siphonophore sampling and identification, which have led to a general knowledge gap about their diversity, distribution and abundance.
Methods: Here, we provide a global overview of the oceanic vertical distribution of siphonophores using DNA metabarcoding data from 77 bulk mesozooplankton samples collected at four different depth ranges (0-200, 200-500, 500-1000, 1000-3000 m depth) along the Atlantic, Pacific, and Indian Oceans during the MALASPINA-2010 circumnavigation expedition.
Nature
September 2024
Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia.
The biological pump supplies carbon to the oceans' interior, driving long-term carbon sequestration and providing energy for deep-sea ecosystems. Its efficiency is set by transformations of newly formed particles in the euphotic zone, followed by vertical flux attenuation via mesopelagic processes. Depth attenuation of the particulate organic carbon (POC) flux is modulated by multiple processes involving zooplankton and/or microbes.
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