A re-appraisal of the total biomass and annual production of Antarctic krill

Atkinson, Angus; Siegel, Volker; Pakhomov, Evgeny A.; Jessopp, Mark; Loeb, Valerie J.

doi:10.1016/j.dsr.2008.12.007

Cited by 308 publications

(231 citation statements)

References 48 publications

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“…All net hauls were oblique or vertical and were taken mainly in the summer months. Full details of this database, including net sampling details, are provided in Atkinson et al (2004Atkinson et al ( , 2008Atkinson et al ( , 2009; including the supplementary method appendices of the first two). The krill and salp density data taken from the rawKRILLBASE are used in their raw form, i.e.…”

Section: Origin Of Datamentioning

confidence: 99%

Distribution of known macrozooplankton abundance and biomass in the global ocean

Moriarty

Buitenhuis

Quéré

et al. 2013

Earth Syst. Sci. Data

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Abstract.Macrozooplankton are an important link between higher and lower trophic levels in the oceans. They serve as the primary food for fish, reptiles, birds and mammals in some regions, and play a role in the export of carbon from the surface to the intermediate and deep ocean. Little, however, is known of their global distribution and biomass. Here we compiled a dataset of macrozooplankton abundance and biomass observations for the global ocean from a collection of four datasets. We harmonise the data to common units, calculate additional carbon biomass where possible, and bin the dataset in a global 1 × 1 degree grid. This dataset is part of a wider effort to provide a global picture of carbon biomass data for key plankton functional types, in particular to support the development of marine ecosystem models. Over 387 700 abundance data and 1330 carbon biomass data have been collected from pre-existing datasets. A further 34 938 abundance data were converted to carbon biomass data using species-specific length frequencies or using species-specific abundance to carbon biomass data. Depth-integrated values are used to calculate known epipelagic macrozooplankton biomass concentrations and global biomass. Global macrozooplankton biomass, to a depth of 350 m, has a mean of 8.4 µg C L −1 , median of 0.2 µg C L −1 and a standard deviation of 63.5 µg C L −1 . The global annual average estimate of macrozooplankton biomass in the top 350 m, based on the median value, is 0.02 Pg C. There are, however, limitations on the dataset; abundance observations have good coverage except in the South Pacific mid-latitudes, but biomass observation coverage is only good at high latitudes. Biomass is restricted to data that is originally given in carbon or to data that can be converted from abundance to carbon. Carbon conversions from abundance are restricted by the lack of information on the size of the organism and/or the absence of taxonomic information. Distribution patterns of global macrozooplankton biomass and statistical information about biomass concentrations may be used to validate biogeochemical and plankton functional type models.Macrozooplankton abundance and biomass dataset

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Section: Origin Of Datamentioning

confidence: 99%

Distribution of known macrozooplankton abundance and biomass in the global ocean

Moriarty

Buitenhuis

Quéré

et al. 2013

Earth Syst. Sci. Data

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“…The model represents interactions between Antarctic krill, four competing krill predator taxa, and the krill fishery in the Scotia Sea and Southern Drake Passage region. This region (FAO statistical subareas 48.1, 48.2 and 48.3) is where 28% of the Southern Ocean krill stock is located (Atkinson et al 2009) and where 83% of the krill catch to date has been taken (Hill 2013).…”

Section: Ecosystem Dynamics Modelmentioning

confidence: 99%

From strategic ambiguity to technical reference points in the Antarctic krill fishery: the worst journey in the world?

Hill

2013

Envir. Conserv.

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SUMMARYThe goals of ecosystem based management (EBM) are strategically ambiguous, meaning that they require interpretation to identify objectives for ecosystem state. Ecosystem states that are useful for achieving such objectives are known as reference points. Soft reference points specify both a state and a probability of the ecosystem being in that state. They are used with simulation models to identify management measures for which the risk of the ecosystem entering an undesirable state is below a specified level. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is responsible for the EBM of Antarctic krill fisheries. CCAMLR used soft reference points for the krill stock in the Scotia Sea and southern Drake Passage to set a regional catch limit. However, this catch limit needs spatial subdivision to protect predators from localized depletion. Modelbased evaluations of different options for subdividing the catch limit used illustrative reference points to assess the depletion risk to multiple predators. This study demonstrates that the apparent risk is sensitive to the choice of reference point and method for aggregating modelled predators. EBM practitioners and stakeholders need to be aware that these factors could therefore bias comparisons of management measures. Nonetheless, qualitative distinctions between different spatial subdivision options are relatively consistent except at high levels of aggregation and extreme reference points. This study also demonstrates a lack of generality in the relationship between current and future ecosystem state. Thus, the EBM goal of maintaining ecosystem resilience implies different reference points for the current state of different ecosystem components. Despite early progress in defining soft reference points for the krill stock, CCAMLR has not yet defined reference points for krill predators. Structured dialogue aimed at identifying collective objectives * Correspondence: Dr Simeon Hill e-mail: sih@bas.ac.uk The online version of this article is published within an Open Access environment subject to the conditions of the Creative Commons Attribution-NonCommercial-ShareAlike licence . The written permission of Cambridge University Press must be obtained for commercial re-use. might be necessary to achieve further progress in CCAMLR and other EBM organizations.

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“…antarctica and Corethron (Korb et al, 2008. The productive waters downstream of South Georgia support a very large biomass of mesozooplankton , macrozooplankton (Atkinson et al, , 2009, mesopelagic fish (Collins et al, 2012) and top predators (Boyd et al, 1994), with significant implications for the amount of POC export out of the mixed layer (Huntley et al, 1991). Upstream of South Georgia, the lack of iron limits phytoplankton growth and phytoplankton biomass is one order of magnitude lower than that is observed downstream of the island (Korb et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Strong contribution of diatom resting spores to deep-sea carbon transfer in naturally iron-fertilized waters downstream of South Georgia

Rembauville

Manno

Tarling

et al. 2016

Deep Sea Research Part I: Oceanographic Research Papers

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a b s t r a c tBiogeochemical and diatom export fluxes are presented from two bathypelagic sediment trap deployments in the Antarctic Zone of the Southern Ocean. One of the sediment traps was deployed in very productive, naturally iron-fertilized waters downstream of South Georgia (P3, 2000 m) and compared to a deployment in moderately productive waters upstream of the island system (P2, 1500 m). At both sites significant diatom export events occurred in spring (November) and contained mostly empty cells that were associated with low particulate organic carbon (POC) fluxes. A summer export pulse occurred one month later at P2 (end February/March) compared to P3 (end January). Diatom fluxes at P3 were one order of magnitude higher than at P2, a difference mainly attributed to the short and intense export of resting spores from Chaetoceros Hyalochaete and Thalassiosira antarctica species. Aside from these resting spores, diatom export assemblages at both sites were dominated by empty Fragilariopsis kerguelensis frustules. The fraction of diatoms exported as empty frustules was considerably lower at P3 (52%) than P2 (91%). This difference was related to the flux of intact diatom resting spores at P3 and may partially explain the lower Si:C export stoichiometry observed at P3 (1.1) compared to P2 (1.5). Through the enumeration of full diatom frustules and subsequent biomass calculations we estimate that diatom resting spores account for 42% of annual POC flux in the productive waters downstream of South Georgia. At both sites the contribution of diatom vegetative stages to POC fluxes was considerably lower (o 5%). From these analyses we conclude that resting spore export contributes towards the slightly higher bathypelagic (POC) flux at P3 (40.6 mmol m À 2 y À 1 ) compared to P2 (26.4 mmol m À 2 y À 1 ). We compared our sediment trap records with previously published diatom assemblage data from the mixed layer and surface sediments (3760 m) around South Georgia. The relative proportion of diatom resting spores within diatom assemblages increases as a function of depth and is explained by selective preservation of their robust frustules. Our study highlights the significance of diatom resting spore export as a carbon vector out of the mixed layer. Furthermore, the contribution or resting spores to POC flux in the bathypelagic ocean and sediments suggests they play a particularly important role in sequestering biologically fixed CO 2 over climatically relevant timescales.

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A re-appraisal of the total biomass and annual production of Antarctic krill

Cited by 308 publications

References 48 publications

Distribution of known macrozooplankton abundance and biomass in the global ocean

Distribution of known macrozooplankton abundance and biomass in the global ocean

From strategic ambiguity to technical reference points in the Antarctic krill fishery: the worst journey in the world?

Strong contribution of diatom resting spores to deep-sea carbon transfer in naturally iron-fertilized waters downstream of South Georgia

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