Modelling the influence of copepod behaviour on faecal pellet export at high latitudes

Wallace, M.I.; Cottier, F.R.; Brierley, A.S.; Tarling, G.A. ORCID: https://orcid.org/0000-0002-3753-5899. 2013 Modelling the influence of copepod behaviour on faecal pellet export at high latitudes. Polar Biology, 36 (4). 579-592. https://doi.org/10.1007/s00300-013-1287-7

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Text (This article has been accepted for publication and will be published by Springer in Polar Biology. The final publication is available at link.springer.com. Copyright Springer.) Wallace et al revised_final.doc - Accepted Version Download (5MB)

Abstract/Summary

The contribution of faecal pellet (FP) production by zooplankton to the downward flux of particulate organic carbon (POC) can vary from <1 % to more than 90 % of total POC. This results from varying degrees of interception and consumption, and hence recycling, of FPs by zooplankton in the upper mixed layers, and the active transport of FP to depth via diel vertical migration (VM) of zooplankton. During mid-summer at high latitudes, synchronised diel VM ceases, but individual zooplankton may continue to make forays into and out of the surface layers. This study considers the relative importance of different VM behaviours on FP export at high latitudes. We focussed on copepods and parameterised an individual-based model using empirical measures of phytoplankton vertical distribution and the rate of FP production, as a function of food availability. FP production was estimated under three different behaviours common to high-latitude environments (1) no VM, (2) foray-type behaviour and (3) synchronised diel VM. Simulations were also made of how each of these behaviours would be observed by an acoustic Doppler current profiler (ADCP). The model found that the type of copepod behaviour made a substantial difference to the level of FP export to depth. In the absence of VM, all FPs were produced above 50 m, where the probability of eventual export to depth was low. In foray-type scenarios, FP production occurred between 0 and 80 m, although the majority occurred between 30 and 70 m depth. Greatest FP production in the deeper layers (>70 m) occurred when diel VM took place. Simulated ADCP vertical velocity fields from the foray-type scenario resembled field observations, particularly with regard to the occurrence of positive anomalies in deeper waters and negative anomalies in shallower waters. The model illustrates that active vertical flux of zooplankton FP can occur at high latitudes even when no synchronised VM is taking place.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1007/s00300-013-1287-7
Programmes:	BAS Programmes > Polar Science for Planet Earth (2009 - ) > Ecosystems
ISSN:	0722-4060
Additional Keywords:	zooplankton, Arctic, vertical migration, carbon flux, foray-type behaviour, satiation sinking, Acoustic Doppler current profiler, fecal pellet
NORA Subject Terms:	Marine Sciences
Date made live:	30 Apr 2013 10:51 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/501661

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