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Here we present a new, pan-North-Atlantic compilation of data on key mesozooplankton species, including the most important copepod, Calanus finmarchicus. Distributional data of eight representative zooplankton taxa, from recent (2000–2009) Continuous Plankton Recorder data, are presented, along with basin-scale data of the phytoplankton colour index. Then we present a compilation of data on C. finmarchicus, including observations of abundance, demography, egg production and female size, with accompanying data on temperature and chlorophyll. This is a contribution by Canadian, European and US scientists and their institutions: http://doi.pangaea.de/10.1594/PANGAEA.820732, http://doi.pangaea.de/10.1594/PANGAEA.824423, http://doi.pangaea.de/10.1594/PANGAEA.828393 (please also see Melle et al., 2013; Castellani and Licandro, 2013; Jónasdóttir et al., 2014).

This paper addresses relationships between the distribution and abundance of zooplankton and its habitat in the northern North Atlantic Ocean. Distributions of ten representative zooplankton taxa, from recent (2000-2009) Continuous Plankton Recorder data, are presented, along with basin-scale patterns of annual sea surface temperature and phytoplankton color. The distribution patterns represent the manifestation of very different physiological, life history and ecological interactions of each taxon with the North Atlantic habitat characteristics. The paper then focuses on a pan-Atlantic compilation of demographic and life history information for the planktonic copepod, Calanus finmarchicus, perhaps one of the most ecologically important and certainly the most studied zooplankton species in the North Atlantic. Abundance, dormancy, egg production and mortality in relation to temperature and phytoplankton biomass, using chlorophyll a as a proxy, are analyzed in the context of understanding factors involved in determining the distribution and abundance of C. finmarchicus across its range. Several themes emerge: (1) transport of C. finmarchicus is from the south to the north in the northeast Atlantic, but from the north to the south in the western North Atlantic, which has implications for understanding population responses to climate forcing on coastal shelves, , (2) recruitment to the youngest copepodite stages occurs during or just after the phytoplankton bloom in the east while it occurs after the bloom in many western sites, (3) while the deep basins in the Labrador Sea and Norwegian Sea are primary sources of C. finmarchicus production, the western North Atlantic marginal seas have an important role in sustaining high C. finmarchicus abundance on the western North Atlantic shelves, (4) differences in mean temperature and chlorophyll concentration between the western and eastern North Atlantic are reflected in regional differences in female body size and egg production responses, (5) differences in functional responses in egg production rate may reflect genetic differences between western and eastern populations, (6) dormancy duration is generally shorter in the deep waters adjacent to the lower latitude western North Atlantic shelves than in the east, and (7) differences in stage-specific mortality rates are related to bathymetry, temperature and potential predators, notably the abundance of congeners Calanus hyperboreus and C. glacialis, which likely feed on early life stages of C. finmarchicus. Two modeling approaches have previously been used to interpret the abundance and distribution of C. finmarchicus in relation to the North Atlantic habitat. A statistical approach based on ecological niche theory and a dynamical modeling approach, based on knowledge of spatial population dynamics and life history and implemented by recent developments in coupled physical-life cycle modeling. The strengths and weaknesses of each approach are discussed. A synthesis of the two modeling approaches to predict North Atlantic zooplankton species shifts, not only for C. finmarchicus, but also for other major taxa, is advocated. While the computational resource requirements and lack of species-specific life history information for physical-biological modeling hinder full application for many zooplankton taxa, use of the approach, where possible, to understand advective influences will provide insight for interpretation of statistical predictions from species distribution models.

New baseline information is presented on biogeography, abundance and distri-bution of euphausiids from discrete depth samples collected throughout the watercolumn to 3000 m at 42 locations along the Mid-Atlantic Ridge (MAR) betweenIceland and the Azores. Eighteen species were recorded, with Euphausia krohni andThysanoessa longicaudata being most abundant. Eight species had not been recordedin the area previously. The Subpolar Front is a northern boundary to somesouthern species, but not a southern boundary to northern ubiquitous species thatshow submergence. Four major species assemblages were identified and character-ized in terms of spatial distribution and species composition. Numerical abun-dance was highly variable but decreased logarithmically with depth. The greatestaverage abundance and the greatest spatial variation in abundance occurred innorthern waters, over the Reykjanes Ridge. Abundance declined less with depth inthe sub-Arctic Intermediate Water/North Atlantic Current Water than in otherareas and water masses. The near bottom layer (0–200 m from the seabed) hadtypically low density of euphausiids. The MAR is generally deeper than the usualdepth distribution of euphausiids (0–300 m), but many species conduct verticalmigrations to ridge crest depths. Euphausiid distribution and abundance patternsappeared only weakly affected by the MAR.KEYWORDS: zooplankton; Euphausiacea; oceanic; deepwater; biogeography;communities; Mid-Atlantic Ridge

Primary production and environmental influences on its intensity were studied on the Faroe shelf during 2004 and 2005. The study area is a small neritic ecosystem, which is relatively well (although variably) separated from the surrounding oceanic environment. Diatoms dominated during the spring bloom in 2004, but due to a combination of low concentrations of essential nutrients, and an apparent shift in the primary nitrogen source from nitrate to regenerated nitrogen, the phytoplankton species composition changed to a dominance of the small flagellate Phaeocystis pouchetii in July. In 2005, the nutrient concentrations did not reach the same low values as in summer 2004, and diatoms dominated the phytoplankton species composition during the productive season. Primary production, based on the 14 C-technique, showed a linear relationship to primary production, based on the Fast Repetition Rate Fluorometer-technique (FRRF), with a regression slope of 1.5 and an r 2 of 0.85. The timing and magnitude of the spring bloom on the shelf is highly variable interannually. Favourable conditions for phytoplankton growth, in terms of the critical depth, were met in March. However, the spring bloom did not occur before mid-May. The specific primary production was high in April and throughout the productive season but was not reflected in the phytoplankton biomass. On the other hand the pattern in the phytoplankton biomass was reflected in the total primary production, indicating the importance of phytoplankton accumulation for bloom development. Advection, most likely, caused most of the apparent loss of primary production during pre-bloom, while grazing by the copepod community accounted for ~ 10% of the loss. Thus, spring bloom formation in the area depends highly on the spatial dispersal of phytoplankton biomass. The annual primary production on the shelf, based on the 14 C-technique, was 201 g C m − 2 y − 1 . Approximately 77 g C m − 2 y − 1 was based on nitrate as nitrogen source, corresponding to a f -ratio of approximately 0.4.

Measurements of hydrography, chlorophyll a, abundance, egg production rates and gut fluorescence of Calanus finmarchicus were made on the northern Mid-Atlantic Ridge, along a north–south transect extending from Iceland to the Azores (∼60–44°N, 25–35°W) in June 2004. In addition, similar data were sampled in the Irminger Sea and on the Reykjanes Ridge in June 2003. The results show marked differences in abundance, phytoplankton ingestion rates and egg production rates from north to south. C. finmarchicus was most abundant in the central Irminger Sea (∼80,000–160,000 individuals m−2, 0–100 m), with abundance declining drastically (

Here we present a new, pan-Atlantic compilation of data on key mesozooplankton species, including the possibly most important copepod, Calanus finmarchicus. Distributional data of ten representative zooplankton taxa, from recent (2000–2009) Continuous Plankton Recorder data, are presented, along with basin-scale data of the phytoplankton colour index. Then we present a compilation of data on C. finmarchicus including observations of abundance, demography, egg production and female size with accompanying data on temperature and chlorophyll. This is a contribution by Canadian, European and US scientists and their institutions. http://doi.pangaea.de/10.1594/PANGAEA.820732, http://doi.pangaea.de/10.1594/PANGAEA.824423, http://doi.pangaea.de/10.1594/PANGAEA.828393.