We studied the response in development times of Calanus finmarchicus and Calanus helgolandicus to changes in temperature and food conditions. Grazing experiments were performed at different temperatures for both species, and the results were implemented in a stage-resolved zooplankton population model that predicted development times from biomass increments controlled by ingestion and metabolic losses. Predictions were validated against development data from the literature, and show that C. finmarchicus develops faster than C. helgolandicus below 11uC and slower above. The different relative development rates of the species are related to different temperature responses in ingestion rates. A temperature increase of 1uC to 2uC may have consequences for the relative contribution of C. helgolandicus and C. finmarchicus to the copepod community, and both seasonal and spatial displacements of the Calanus populations can be expected under climate change.

We examined and quantified the contributions of copepods and appendicularians to the vertical flux of carbon during autumn and spring in Gullmar Fjord (west coast of Sweden). Faecal pellet-production rate was determined for major copepod and appendicularian species. In addition, house-production rates were estimated for the appendicularian Oikopleura dioica. Vertical flux of pigments, faecal carbon and appendicularian houses were measured using short-term (24 h) deployments of sediment traps at 2 depths (15 and 30 m). Copepods dominated the community biomass in both spring and autumn and their pellets dominated the faecal carbon flux. O. dioica houses with attached detritus were an important component of the biogenic carbon flux in October (15.3 mg C m -2 d -1), equalling the contribution from copepods at 15 m and 50% of the flux at 30 m. At that time, we observed a loss rate of 70% d -1 of the houses produced in the water column. In the spring, although Fritillaria borealis dominated the appendicularians, its houses did not appear to contribute to the biogenic flux. Our results suggest that oikopleurids and fritillariids may not operate equivalently in biogeochemical cycles. Because of the significant contribution of appendicularians to carbon fluxes, they should be incorporated in future flow models of coastal oceans KEY WORDS: Carbon flux · Appendicularians · Copepods · Faecal pellet production · Marine snow Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 241: [125][126][127][128][129][130][131][132][133][134][135][136][137][138] 2002 extruded in short time intervals as faecal pellets (López-Urrutia & Acuña 1999). Some of these faecal pellets, together with uneaten particles, eventually clog the house, which is then abandoned and replaced by a new house, approximately 4 to 6 times per day (Deibel 1988, Alldredge 1992, Hansen et al. 1996, Sato et al. 2001. Thus, appendicularian houses together with their faecal pellets may constitute an important component of marine snow (Alldredge & Gotschalk 1990, Hansen et al. 1996. Furthermore, due to the high efficiency with which appendicularians ingest nanoplankton and picoplankton (King et al. 1980, Deibel 1988, Deibel & Lee 1992, Acuña et al. 1996, they constitute a pathway through which small cells that otherwise do not sink may be transported out of the euphotic zone. Consequently, when appendicularians are abundant, small phytoplankton cells may contribute much more to the vertical flux than when the community is dominated by copepods (Urban et al. 1992, Hansen et al. 1996.Oikopleura and Fritillaria species are abundant pelagic tunicates in coastal waters (e.g. Acuña et al. 1995, Gorsky et al. 2000. On the western Norwegian coast, O. dioica is one of the most widely distributed species (Gorsky et al. 2000). In the Kattegat, appendicularians also represent an important component of the zooplankton community during the autumn and spring blooms (Nielsen & Hansen 1999). The abundance of copepods in these bo...

In order to assess the potential responses of Greenland's coastal ecosystems to future climate change, we studied the hydrography and distribution of metazooplankton, along a transect from the slope waters beyond Fyllas Banke to the inner part of Godthåbsfjord, West Greenland, in July and August 2008, and estimated feeding rates for some of the larger species groups. Within the 4 regional domains that were covered in the study (continental slope, continental shelf, outer sill region, and main fjord basin), salty coastal water and glacial runoff mixed to various extents, and 7 water masses with specific characteristics were identified. The common large copepod species were Calanus finmarchicus, C. glacialis, C. hyperboreus, and Metridia longa. Small copepod genera included Microsetella, Pseudocalanus, and Oithona, while rotifers and gastropods (primarily pteropods) were also found in high abundance. Species could be linked to the specific water masses, e.g. Calanus spp. were primarily associated with oceanic or coastal waters, whereas M. longa, Microsetella sp., Pseudocalanus sp., and rotifers were mostly found inside the fjord. The combined biomass of the large zooplankton species (5.5 × 10 3 mg C m -2 ) was less than that of the small species (6.8 × 10 3 mg C m -2 ) averaged across all sampled stations along the transect. Estimated in situ grazing rates for the large copepod species were <10% of their maximum rates, indicating food limitation. The major predatory zooplankton groups, Pareuchaeta norvegica and chaetognaths, had estimated predation effects of <1% d -1 on the prey community. The dominance of small zooplankton species within the fjord contradicts the traditional emphasis on large, lipid-rich zooplankton species in the arctic seas, and suggests that the planktonic food web structure inside the glacial fjord was different from that of the system outside.

This study describes differences in plankton community structure and in chemical and physical gradients between the offshore West Greenland Current system and inland regions close to the Greenland Ice Sheet during the post-bloom in Godthåbsfjorden (64°N, 51°W). The offshore region had pronounced vertical mixing, with centric diatoms and Phaeocystis spp. dominating the phytoplankton, chlorophyll (chl) a (0.3 to 3.9 µg l-1) was evenly distributed and nutrients were depleted in the upper 50 m. Ciliates and heterotrophic dinoflagellates constituted equal parts of the protozooplankton biomass. Copepod biomass was dominated by Calanus spp. Primary production, copepod production and the vertical flux were high offshore. The water column was stratified in the fjord, causing chl a to be concentrated in a thin sub-surface layer. Nutrients were depleted above the pycnocline, and Thalassiosira spp. dominated the phytoplankton assemblage close to the ice sheet. Dinoflagellates dominated the protozooplankton biomass, whereas copepod biomass was low and was dominated by Pseudocalanus spp. and Metridia longa. Primary production was low in the outer part of the fjord but considerably higher in the inner parts of the fjord. Copepod production was exceeded by protozooplankton production in the fjord. The results of both physical/chemical factors and biological parameters suggest separation of offshore and fjord systems.

Phytoplankton and copepod succession was investigated in Disko Bay, western Greenland from February to July 2008. The spring phytoplankton bloom developed immediately after the breakup of sea ice and reached a peak concentration of 24 mg chl a m -3 2 wk later. The bloom was analyzed during 3 phases: the developing, the decaying, and the post-bloom phases. Grazing impact by the copepod community was assessed by 4 methods; gut fluorescence, in situ faecal pellet production, and egg and faecal pellet production from bottle incubations. Calanus spp. dominated the mesozooplankton community. They were present from the initiation of the bloom but only had a small grazing impact on the phytoplankton. Consequently, there was a close coupling between the spring phytoplankton bloom and sedimentation of particulate organic carbon (POC). Out of 1836 ± 180 mg C m -2 d -1 leaving the upper 50 m, 60% was phytoplankton based carbon (PPC). The composition and quality of the sedimenting material changed throughout the bloom succession from PPC dominance in the initial phase with a POC/PON ratio close to 6.6 to a dominance of amorphous detritus with a higher POC/PON ratio (>10) in the postbloom phase. The succession and fate of the phytoplankton spring bloom was controlled by nitrogen limitation and subsequent sedimentation, while grazing-mediated flux by the Calanus-dominated copepod community played a minor role in the termination of the spring bloom of Disko Bay.