scholarly journals Egg production and hatching success in the calanoid copepods Calanus helgolandicus and Calanus finmarchicus in the North Sea from March to September 2001

2005 ◽  
Vol 27 (12) ◽  
pp. 1239-1259 ◽  
Author(s):  
Sigrún H. Jónasdóttir ◽  
Nguyen Huu Trung ◽  
Frank Hansen ◽  
Sanne Gärtner
Keyword(s):  
North Sea ◽  
Egg Production ◽  
Hatching Success ◽  
Calanus Finmarchicus ◽  
Calanoid Copepods ◽  
The North ◽  
The North Sea ◽  
Calanus Helgolandicus

scholarly journals Selective feeding by pelagic fish in the Belgian part of the North Sea

2013 ◽  
Vol 71 (4) ◽  
pp. 808-820 ◽  
Author(s):  
Karl Van Ginderdeuren ◽  
Sofie Vandendriessche ◽  
Yves Prössler ◽  
Hakimu Matola ◽  
Magda Vincx ◽  
...  
Keyword(s):  
North Sea ◽  
Prey Species ◽  
Pelagic Fish ◽  
Horse Mackerel ◽  
Calanoid Copepods ◽  
Oikopleura Dioica ◽  
The North ◽  
Fullness Index ◽  
The North Sea ◽  
Prey Items

Abstract Pelagic fish and their planktonic prey are susceptible to a changing climate, giving rise to mismatches and planktonic bottlenecks. A detailed examination of the feeding ecology of pelagic fish can provide valuable insights in the causes and consequences of these phenomena. The present study investigated the diets of both juvenile and adult herring, sprat, horse mackerel, and adult mackerel in the Belgian part of the North Sea (BPNS) in relation to the distribution of zooplankton and ambient abiotic conditions. A study sampling pelagic fish and zooplankton simultaneously every month during consecutive years, and spanning nearshore to offshore sampling locations, is unprecedented in the southern North Sea. In all, 71 prey taxa were found in 725 stomachs of fish gathered at ten stations, sampled monthly in 2009 and 2010. The proportion of fish with empty stomachs was low (11%), and the number of prey species ranged from 0 to 21 sp. per stomach. The diet of herring and sprat was dominated by calanoid copepods, but herring stomachs also contained many decapod larvae, amphipods, cumaceans, and mysids. Mackerel added sandeels to an otherwise planktivorous diet. Horse mackerel consumed both benthic and pelagic prey. The highest frequency of occurrence in the stomachs was observed for the calanoid copepods Temora longicornis (33 408 of all 55 004 prey items identified) and Centropages hamatus (5003 times found). The fullness index ranged between 0 and 20.6, and averaged highest for sprat (0.86), followed by herring (0.60), horse mackerel (0.26), and mackerel (0.24). We observed a different composition of zooplankton species and life stages in the plankton samples compared with those in the fish stomachs. More adult and female copepods were eaten than the plankton samples would suggest. Also, the calanoid copepod Acartia clausi, the most common calanoid species in the BPNS, was barely eaten, as was the case for fish eggs and larvae, and for common planktonic species known to be preyed upon elsewhere (e.g. Oikopleura dioica, Evadne nordmanni, Euterpina acutifrons). Additionally, plankton densities averaged highest in spring and at midshore (20–30 km from shore) stations, but fullness index was highest nearshore (<12 km from shore) and (apart from sprat) in summer. A significant correlation between fullness index and total density of planktonic prey species was not observed, indicating that zooplankton densities were not restrictive. Yet the fact that more than 100 plankton species occurred in the plankton samples and just two of these (T. longicornis and C. hamatus) accounted for nearly three-quarters of all ingested prey items leads us to conclude that even minor changes in the ecology or phenology of these dominant zooplankters could have profound effects on pelagic fish stocks.

Studies on a Calanus Patch III. The quantity of food eaten by Calanus finmarchicus

1963 ◽  
Vol 43 (2) ◽  
pp. 349-371 ◽  
Author(s):  
D. H. Cushing ◽  
T. Vucetic
Keyword(s):  
Water Temperature ◽  
North Sea ◽  
Calanus Finmarchicus ◽  
Algal Production ◽  
The North ◽  
The North Sea ◽  
Grazing Mortality ◽  
And Diffusion ◽  
Grazing Capacity ◽  
Food Consumed

The purpose of this paper is to assess the grazing capacity of Calanus finmar-chicus (Gunner.) in terms of the quantity of food eaten in the sea. The part played in the growth of the animal by the quantity eaten will only be briefly discussed. The parts played by nutrient lack, sinking and diffusion on the algal productive rates will also be discussed, leading to the conclusion that grazing mortality is the most effective controlling agent on algal production.A subsidiary purpose of this paper is to relate changes in the weight of Calanus finmarchicus to changes in food consumed and to changes in water temperature. Measurements of C. finmarchicus have been made by a number of workers (Adler & Jespersen, 1920; Russell, 1928; Marshall, 1933; Stormer, 1929; Bogorov, 1934; Jespersen, 1939; Clarke & Zinn, 1937). It will be shown that in the North Sea, in spring, the greatest changes in weight are most readily related to changes in quantities of food consumed.

Feeding, Growth and Reproduction of the Marine Planktonic Copepod Pseudo-Calanus Elongatus Boeck

1976 ◽  
Vol 56 (2) ◽  
pp. 327-344 ◽  
Author(s):  
G.-A. Paffenhöfer ◽  
R. P. Harris
Keyword(s):  
Food Web ◽  
North Sea ◽  
Calanoid Copepods ◽  
Small Copepod ◽  
The North ◽  
Controlled Conditions ◽  
Food Concentrations ◽  
Food Species ◽  
The North Sea ◽  
Growth And Reproduction

INTRODUCTIONThe development of techniques to culture calanoid copepods over multiple generations in the laboratory has resulted in considerable advances in knowledge about a group of animals of major importance in the marine food web. A series of extensive studies have been made of two species of large calanoids, Calanus helgolandicus (Claus) (Mullin & Brooks, 1967, 1970a, 1970b; Paffenhöfer, 1970, 1971, 1976a, 1976b), and Rhincalanus nasutus Giesbrecht (Mullin & Brooks, 1967, 1970a, 1970b). Feeding, growth, and reproduction have been studied under controlled conditions, using different temperatures, food species, and food concentrations. Some of the information gained in these studies has been incorporated into a simulation model of the planktonic ecosystem of the North Sea (Steele, 1974). However, in the North Sea and in many other sea areas species of small copepod probably form an important component of the food web. Little information is available on the quantitative biology of these small copepods under controlled conditions.

scholarly journals Reproductive cycles of dominant calanoid copepods in the North Sea

2001 ◽  
Vol 209 ◽  
pp. 219-229 ◽  
Author(s):  
C Halsband ◽  
HJ Hirche
Keyword(s):  
North Sea ◽  
Calanoid Copepods ◽  
The North ◽  
The North Sea ◽  
Reproductive Cycles

Composition and origin of milky water in the North Sea

1980 ◽  
Vol 60 (3) ◽  
pp. 759-768 ◽  
Author(s):  
J. K. Volkman ◽  
R. R. Gatten ◽  
J. R. Sargent
Keyword(s):  
North Sea ◽  
Mass Spectra ◽  
Oxidative Degradation ◽  
Wax Esters ◽  
Calanus Finmarchicus ◽  
Wax Ester ◽  
Capillary Gc ◽  
The North ◽  
The North Sea ◽  
Calanus Species

An occurrence of ‘milky water’ which covered a wide area of the North Sea in June 1975 is described. The water contained 20 mg/1 of an oil which was shown by capillary GC-MS to consist mainly (> 80%) of two wax esters 34:1 and 36:1. Analysis of the acids and alcohols released by hydrolysis, and interpretation of the wax ester mass spectra, indicated that the 34:1 ester was almost entirely composed of the alcohol-acid combination 20:1–14:0 and the 36:1 ester was composed of 22:1–14:0 (75%) and 20:1–16:0 (19%). Wax esters of virtually the same composition predominate in the lipids of the copepod Calanus finmarchicus which has the implication that the ‘milky water’ was caused by ageing of the oil released following a mass mortality of copepods. The lack of polyunsaturated wax esters and of astaxanthin is ascribed to oxidative degradation of these labile lipids following release into the sea. A copepod origin for the milky water is further supported by its containing small amounts of cholesterol and pristane, both of which are common to Calanus species.

scholarly journals Copepod feeding behaviour and egg production during a dinoflagellate bloom in the North Sea

Harmful Algae ◽  
2006 ◽  
Vol 5 (1) ◽  
pp. 102-112 ◽  
Author(s):  
Sandra Jansen ◽  
Christian Wexels Riser ◽  
Paul Wassmann ◽  
Ulrich Bathmann
Keyword(s):  
North Sea ◽  
Feeding Behaviour ◽  
Egg Production ◽  
The North ◽  
The North Sea ◽  
Dinoflagellate Bloom

Variation in fecundity in the lesser sandeel: implications for regional management

2010 ◽  
Vol 91 (6) ◽  
pp. 1273-1280 ◽  
Author(s):  
Philip Boulcott ◽  
Peter J. Wright
Keyword(s):  
North Sea ◽  
Egg Production ◽  
Oocyte Diameter ◽  
Isolated Populations ◽  
Potential Fecundity ◽  
North East ◽  
The North ◽  
Regional Management ◽  
Parental Stock ◽  
The North Sea

The number of eggs produced by a parental stock is central to fisheries advice on recruitment potential. However, stock based estimates of egg production may give a misleading index of recruitment potential in stocks containing several reproductively isolated populations. This paper examines the ability of length, condition and oocyte developmental stage to predict levels of potential fecundity in the sandeel, Ammodytes marinus, in three important fished areas in the North Sea. Our results indicate that regional variation in this relationship exists, with fecundity in central areas of the North Sea being higher than those found just off the north-east UK. Oocyte diameter was also found to have a significant effect on potential fecundity, suggesting a down-regulation of oocyte numbers arising from pre-ovulatory atresia, however, this effect was not apparent in every model tested. Our findings have relevance to the local sustainability of spawning components and thus the regional management of the North Sea sandeel stock.

scholarly journals Does copepod size determine food consumption of particulate feeding fish?

2013 ◽  
Vol 71 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Mikael van Deurs ◽  
Marja Koski ◽  
Anna Rindorf
Keyword(s):  
Food Consumption ◽  
North Sea ◽  
Fish Larvae ◽  
Handling Time ◽  
Growth Conditions ◽  
Calanus Finmarchicus ◽  
Fish Feeding ◽  
The North ◽  
The North Sea ◽  
Particulate Feeding

Abstract van Deurs, M., Koski, M., and Rindorf, A. Does copepod size determine food consumption of particulate feeding fish? – ICES Journal of Marine Science, 71: . The climate-induced reduction in the mean copepod size, mainly driven by a decrease in the abundance of the large Calanus finmarchicus around 1987, has been linked to the low survival of fish larvae in the North Sea. However, to what extent this sort of reduction in copepod size has any influence on adult particulate feeding fish is unknown. In the present study, we investigated the hypothesis that the availability of the large copepods determines food consumption and growth conditions of lesser sandeel (Ammodytes marinus) in the North Sea. Analysis of stomach content suggested that food consumption is higher for fish feeding on large copepods, and additional calculations revealed how handling time limitation may provide part of the explanation for this relationship. Comparing stomach data and zooplankton samples indicated that lesser sandeel actively target large copepods when these are available. Finally, we observed that the length of lesser sandeel began to decrease in the late 1980s, simultaneously with the C. finmarchicus decline.

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