scholarly journals Characteristics of Calanus finmarchicus dormancy patterns in the Northwest Atlantic

2007 ◽  
Vol 65 (3) ◽  
pp. 339-350 ◽  
Author(s):  
Catherine L. Johnson ◽  
Andrew W. Leising ◽  
Jeffrey A. Runge ◽  
Erica J. H. Head ◽  
Pierre Pepin ◽  
...  
Keyword(s):  
Calanus Finmarchicus ◽  
Temperature History ◽  
Gonad Maturation ◽  
Total Abundance ◽  
Northwest Atlantic ◽  
Planktonic Copepod ◽  
Average Surface ◽  
Copepodid Stage ◽  
Timing Of Entry ◽  
Calanus Species

Abstract Johnson, C. L., Leising, A. W., Runge, J. A., Head, E. J. H., Pepin, P., Plourde, S., and Durbin, E. G. 2008. Characteristics of Calanus finmarchicus dormancy patterns in the Northwest Atlantic. – ICES Journal of Marine Science, 65: 339–350. Demographic time-series from four fixed stations in the Northwest Atlantic Ocean demonstrate variable timing of entry into and emergence from dormancy in subpopulations of the planktonic copepod Calanus finmarchicus. A proxy for timing of entry was established as the date each year when the proportion of the fifth copepodid stage (CV) in the subpopulation rose to half its overall climatological maximum CV proportion at that station. The proxy for timing of emergence at each station was set as the first date when adults were more than 10% of the total abundance of copepodid stages. An alternate emergence proxy date was determined by back-calculating the spawning dates of the first early copepodid stages appearing in spring, using a stage-structured, individual-based model. No single environmental cue (photoperiod, surface temperature, or average surface-layer chlorophyll a concentration) consistently explained entry or emergence dates across all stations. Among hypotheses put forward to explain dormancy in Calanus species, we cannot eliminate the lipid accumulation window hypothesis for onset of dormancy or a lipid-modulated endogenous timer controlling dormancy duration. The fundamental premise of these hypotheses is that individuals can only enter dormancy if their food and temperature history allows them to accumulate sufficient lipid to endure overwintering, moult, and undergo early stages of gonad maturation.

scholarly journals Contribution of Calanus species to the mesozooplankton biomass in the Barents Sea

2017 ◽  
Vol 75 (7) ◽  
pp. 2342-2354 ◽  
Author(s):  
Johanna Myrseth Aarflot ◽  
Hein Rune Skjoldal ◽  
Padmini Dalpadado ◽  
Mette Skern-Mauritzen
Keyword(s):  
Barents Sea ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Calanus Finmarchicus ◽  
The Arctic ◽  
Arctic Water ◽  
Mesozooplankton Biomass ◽  
The Barents Sea ◽  
Main Driver ◽  
Calanus Species

Abstract Copepods from the genus Calanus are crucial prey for fish, seabirds and mammals in the Nordic and Barents Sea ecosystems. The objective of this study is to determine the contribution of Calanus species to the mesozooplankton biomass in the Barents Sea. We analyse an extensive dataset of Calanus finmarchicus, Calanus glacialis, and Calanus hyperboreus, collected at various research surveys over a 30-year period. Our results show that the Calanus species are a main driver of variation in the mesozooplankton biomass in the Barents Sea, and constitutes around 80% of the total. The proportion of Calanus decreases at low zooplankton biomass, possibly due to a combination of advective processes (low C. finmarchicus in winter) and size selective foraging. Though the Calanus species co-occur in most regions, C. glacialis dominates in the Arctic water masses, while C. finmarchicus dominates in Atlantic waters. The larger C. hyperboreus has considerably lower biomass in the Barents Sea than the other Calanus species. Stages CIV and CV have the largest contribution to Calanus species biomass, whereas stages CI-CIII have an overall low impact on the biomass. In the western area of the Barents Sea, we observe indications of an ongoing borealization of the zooplankton community, with a decreasing proportion of the Arctic C. glacialis over the past 20 years. Atlantic C. finmarchicus have increased during the same period.

scholarly journals Long-term seasonal and spatial patterns in mortality and survival of Calanus finmarchicus across the Atlantic Zone Monitoring Programme region, Northwest Atlantic

2009 ◽  
Vol 66 (9) ◽  
pp. 1942-1958 ◽  
Author(s):  
Stéphane Plourde ◽  
Pierre Pepin ◽  
Erica J. H. Head
Keyword(s):  
Population Growth ◽  
Spatial Patterns ◽  
Phytoplankton Biomass ◽  
Mortality Rates ◽  
Monitoring Programme ◽  
Calanus Finmarchicus ◽  
Northwest Atlantic ◽  
Specific Mortality ◽  
Main Factor

Abstract Plourde, S., Pepin, P., and Head, E. J. H. 2009. Long-term seasonal and spatial patterns in mortality and survival of Calanus finmarchicus across the Atlantic Zone Monitoring Programme region, Northwest Atlantic. – ICES Journal of Marine Science, 66: 1942–1958. The vertical life table method was used to estimate stage-specific daily mortality rates and survival from 1999 to 2006 for Calanus finmarchicus sampled in the Canadian Atlantic Zone Monitoring Programme, which covers the Newfoundland–Labrador Shelf (NLS), Gulf of St Lawrence (GSL), and Scotian Shelf (SS). Stage-specific mortality rates and survival showed significant regional and seasonal differences, with the largest signal associated with variations in temperature. Density-dependent mortality, associated with the abundance of C6 females, was the main factor influencing mortality in the egg–C1 transition during the period of population growth in spring on the SS, and in summer in the GSL and on the NLS. In autumn, mortality in egg–C1 was positively related to temperature and negatively related to phytoplankton biomass, with particularly high mortality rates on the SS. The integration of our results into stage-specific recruitment rates from egg to C5 revealed that C. finmarchicus populations experience their greatest loss (mortality) during the egg–C1 transition. Loss during development to C1 was greater in the GSL than in the other regions during the period of population growth, resulting in lower recruitment success in the GSL. In autumn, C. finmarchicus showed low stage-specific daily recruitment rates on the SS at high temperatures, and low phytoplankton biomass compared with those in the GSL and on the NLS. Our findings reinforce the necessity of describing regional and seasonal patterns in mortality and survival to understand factors controlling the population dynamics of C. finmarchicus.

Importance of Feeding, Direct Uptake from Seawater, and Transfer from Generation to Generation in the Accumulation of an Organochlorine (p,p′-DDT) by the Marine Planktonic Copepod Calanus finmarchicus

1981 ◽  
Vol 38 (1) ◽  
pp. 101-119 ◽  
Author(s):  
Gareth C. Harding ◽  
W. Peter Vass ◽  
Ken F. Drinkwater
Keyword(s):  
Equilibrium Concentration ◽  
Calanus Finmarchicus ◽  
Planktonic Copepod ◽  
Model Simulations ◽  
Marine Copepod ◽  
Planktonic Crustaceans

The accumulation of an organochlorine by the marine copepod Calanus finmarchicus, through feeding on contaminated phytoplankton, 14C-p,p′-DDT labeled Thalassiosira weisflogii, was measured. At "normal" densities, ≈ 60 μg C/L, the copepod retained 60–70% of the DDT ingested following gut egestion, but under "bloom" conditions, ≈ 600 μg C/L, retained as little as 10%. These results enable us to incorporate feeding and generation transfer terms into an earlier model of DDT flux between seawater and planktonic crustaceans. Model simulations indicate that it is not necessary to invoke direct uptake from seawater to arrive at published levels of ΣDDT in copepods, even when our lowest experimental DDT feeding efficiencies are used. We predict that the potential for rapidly developing Calanus to accumulate DDT from generation to generation will reach an equilibrium concentration after 12 generations but that an alternating equilibrium of generations will occur within four generations in a two-season temperature environment.Key words: p,p′-DDT, uptake, clearance, feeding, assimilation, copepods, Calanus finmarchicus

scholarly journals Characteristics of egg production of the planktonic copepod, Calanus finmarchicus, in the Labrador Sea: 1997–2010

2012 ◽  
Vol 35 (2) ◽  
pp. 281-298 ◽  
Author(s):  
Erica J. H. Head ◽  
Leslie R. Harris ◽  
Marc Ringuette ◽  
Robert W. Campbell
Keyword(s):  
Egg Production ◽  
Calanus Finmarchicus ◽  
Labrador Sea ◽  
Planktonic Copepod

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.

Egg Weight, Fecundity, and Gonad Weight Variability among Northwest Atlantic Herring (Clupea harengus) Populations

1992 ◽  
Vol 49 (10) ◽  
pp. 2045-2054 ◽  
Author(s):  
Rodney G. Bradford ◽  
Robert L. Stephenson
Keyword(s):  
Clupea Harengus ◽  
Gonad Maturation ◽  
Atlantic Herring ◽  
Gonad Weight ◽  
Maturation Period ◽  
Egg Weight ◽  
Northwest Atlantic ◽  
Different Seasons ◽  
Ripe Ovary ◽  
Storage Energy

Egg weight varies among northwest Atlantic herring (Clupea harengus) populations that spawn in different seasons (n = 12), but the range in weights is less than half of that known for northeast Atlantic populations. Egg weights were similar for both spring (May–June)- and autumn (August–October)-spawning herring (1.06 ×) and most dissimilar between spring- and summer (July)-spawning herring (1.21 ×). Mean population egg weights were not correlated with temperature either at spawning or for the last 2 mo of the egg development period. The product of egg weight and fecundity (standardized to length) differed between spring- and autumn-spawning herring of the southern Gulf of St. Lawrence. Spring-spawners, particularly smaller fish [Formula: see text], have lower ripe ovary weights than do autumn-spawning herring. Differences between spawning seasons in the relative allocation of storage energy to gonad and metabolism, a process mediated by the duration of the gonad maturation period, are the likely basis for the observed patterns.

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