Archive for midwater

Lasers shed light on giant larvacean filtration impact on the ocean’s biological pump

Posted by mmaheigan 
· Thursday, January 4th, 2018 

To accurately assess the impacts of climate change, we need to understand how atmospheric carbon is transported from surface waters to the deep sea. Grazers and filter feeders drive the ocean’s biological pump as they remove and sequester carbon at various rates. This pump extends down into the midwater realm, the largest habitat on earth. Giant larvaceans are fascinating and enigmatic occupants of the upper 400 m of the water column, where they build complex filtering structures out of mucus that can reach diameters greater than 1 m in longest dimension (Figure 1A). Because of the fragility of these structures, direct measurements of filtration rates require us to study them in situ. We developed DeepPIV, an ROV-deployable instrument (Figure 1B) to directly measure fluid motion and filtration rates in situ (Figure 1C).

Figure 1. (A) Traditional view of a giant larvacean illuminated by white ROV lights. (B) DeepPIV instrument is seen attached to Monterey Bay Aquarium Research Institute’s (MBARI) MiniROV. (C) DeepPIV-illuminated interior view of a giant larvacean house, where particle motion in ambient seawater serves as a proxy for fluid motion. White arrows in (A) and (C) indicate larvacean head/trunk; white arrow in (B) indicates DeepPIV.

The filtration rates we measured for giant larvaceans are far greater than for any other zooplankton filter feeder. When combined with abundance data from a 22-year time series, the grazing impact of giant larvaceans indicates that within 13 days, they can filter the total volume of water within their habitable depth range (~100-300 m; based on maximum abundance and measured filtration rates). Our results reveal that the contribution of giant larvaceans to vertical carbon flux is much greater than previously thought. Small larvaceans, which are present in the water column in even larger quantities than giant larvaceans, may also have a measurable impact on carbon fluxes. New technologies such as DeepPIV are yielding more quantitative observations of midwater filter feeders, which is improving our understanding of the roles that deep-water biota play in the long-term removal of carbon from the atmosphere.

Read the full journal article: http://advances.sciencemag.org/content/3/5/e1602374.full

Authors: (All at MBARI)
Kakani Katija
Rob E. Sherlock
Alana D. Sherman
Bruce H. Robison

Filter by Keyword

acidification air-sea interactions aragonite saturation state arctic argo Atlantic atmospheric CO2 atmospheric nitrogen deposition autonomous platforms bcg-argo biogenic silica biogeochemical cycles biological pump bloom blue carbon bottom water calcification California Current System carbon-climate feedback carbon cycle carbon dioxide Caribbean CCS changing marine ecosystems changing ocean chemistry climate change coastal acidification Coastal ocean cobalt community composition conservation cooling effect coral reefs deep ocean deep waters diatoms DOC domoic acid eddy eddy/eddies Education Ekman transport emissions ENSO enzyme equatorial regions estuarine and coastal carbon flux estuarine and coastal carbon fluxes EXPORTS fecal pellets filter feeders fisheries floats fluorescence food webs forams GEOTRACES gliders greenhouse gas Gulf of Maine Gulf of Mexico Gulf Stream gyre harmful algal bloom hotspots human impact ice cover iron iron fertilization isotopes jelly fall katabatic winds Kelvin waves kuroshio larvaceans lateral carbon flux lateral transport lidar ligands mangroves marine snowfall marshes meeting report mesopelagic mesoscale mesoscale processes metals methane microbes microlayer microscale midwater mixed layer mixotrophy modeling models mode water formation molecular diffusion NASA net community production new technology nitrogen nitrogen fixation north atlantic north pacific nutricline nutrient budget nutrient cycling nutrient limitation ocean acidificat ocean acidification ocean carbon uptake and storage ocean color ocean observatories ocean observing oligotrophic OMZ open ocean organic particles outer ocean oxygen paleoceanography particle flux pCO2 PDO pH Phaeodaria phosphorus photosynthesis physical processes physiology phytoplankton plankton polar regions pollutants primary production pteropods remineralization remote sensing residence time respiration rivers Rossby waves Ross Sea ROV salinity satellite scale seagrass seasonality seasonal patterns sensors shelf system ship-based observations sinking particles southern ocean submesoscale subpolar subtropical surface ocean teleconnections temperature thermohaline time-series top predators trace elements transfer efficiency transient features trophic transfer tropical turbulence upper ocean upper water column upwelling US CLIVAR velocity gradient ventilation vertical flux vertical migration vertical transport western boundary currents wetlands winter mixing working group zooplankton

Copyright © 2018 - OCB Project Office, Woods Hole Oceanographic Institution, 266 Woods Hole Rd, MS #25, Woods Hole, MA 02543 USA Phone: 508-289-2838  •  Fax: 508-457-2193  •  Email: ocb_news@us-ocb.org

link to nsflink to noaalink to WHOI

Funding for the Ocean Carbon & Biogeochemistry Project Office is provided by the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA). The OCB Project Office is housed at the Woods Hole Oceanographic Institution.