Vertical distribution of copepods (all developmental stages) and other zooplankton during spring bloom in the fladen ground area of the north sea

Krause, Michael; Trahms, J.

doi:10.1016/0077-7579(82)90032-1

Cited by 22 publications

(10 citation statements)

References 9 publications

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“…Temperature data were measured by conductivity temperature depth (CTD) sampling every 6 h (Soetje & Huber 1980; a detailed account on the thermal structure at the central station during FLEX 1976 may be found there). Chl a concentrations were estimated in situ down to 80 or 100 m depth using a submersible fluorometer (Elektro Optic Suarez, Krause & Trahms 1982).…”

Section: Methodsmentioning

confidence: 99%

“…This study sought to understand spring bloom dynamics in the northern North Sea, in a region where the influence of horizontal advection is relatively small. Some of the important topics that have been addressed include spring succession of the plankton community (Krause & Radach 1980, Williams & Lindley 1980a, temporal activity and feeding patterns of zooplankton (Daro 1980, Fransz & van Arkel 1980, horizontal distribution of zooplankton biomass (Solow & Steele 1995), habitat choice and patterns of vertical migrations (Krause & Trahms 1982, Krause & Radach 1989, and aspects of zooplankton population dynamics (Lindley & Williams 1980, Williams & Lindley 1980b, Krause & Trahms 1983. Reliable techniques for estimating zooplankton mortality rates were not available to these authors; hence, it has not been possible to include quantitative considerations about mortality until now.…”

Section: Introductionmentioning

confidence: 99%

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Stage-specific mortality of Calanus finmarchicus, Pseudocalanus elongatus and Oithona similis on Fladen Ground, North Sea, during a spring bloom

Eiane

Ohman²

2004

Mar. Ecol. Prog. Ser.

110

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We used Woods Population Surface Method to estimate stage-specific mortality rates for populations of Calanus finmarchicus, Pseudocalanus elongatus, and Oithona similis from abundance data obtained during the Fladen Ground Experiment (FLEX 1976) in the northern North Sea. Temperatures from the day and night depth distributions of each developmental stage were used to force temperature functions for the duration of developmental stages. In addition, we considered the influence of potential food-limitation of development, which had only minor effects on the mortality estimates. We show that the risk of mortality changes substantially over the life span of the animals, with notable differences among species. O. similis, in particular, shows negligible losses after naupliar stages 1 and 2, which may account for its numerical dominance in many ocean regions. Differences among taxa are poorly explained by allometry alone and are instead related to species-and stagespecific differences in behavior. The vertical migration behavior of late developmental stages of C. finmarchicus (i.e. their choice of habitat) might help to reduce mortality risk.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stage-specific mortality of Calanus finmarchicus, Pseudocalanus elongatus and Oithona similis on Fladen Ground, North Sea, during a spring bloom

Eiane

Ohman²

2004

Mar. Ecol. Prog. Ser.

110

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“…Williams and Lindley, 1980a;Krause and Trahms, 1982;Fransz and Diel, 1984;Fransz and Gieskes, 1984;Kiørboe and Johansen, 1986;Roff et al, 1988;Hay et al, 1991), there are very few which span the entire annual cycle. The only data set which has the spatial and temporal coverage for our purposes is that from the Continuous Plankton Recorder (CPR) programme (e.g.…”

Section: Planktonmentioning

confidence: 96%

Seasonal variation in the consumption of food by fish in the North Sea and implications for food web dynamics

Greenstreet

Bryant

Broekhuizen

et al. 1997

ICES Journal of Marine Science

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Previous North Sea food web studies are reviewed. These studies used estimates of primary production and fish energy requirements, then manipulated the energy flow pathway between the two to balance the budget. The resulting pathways largely ignored actual fish diets and consumption rates. In the present paper, North Sea biomass flow food webs are constructed for each quarter of the year from published estimates of fish abundance, diet and daily food consumption, and using long-term Continuous Plankton Recorder and North Sea benthos survey data. Estimates of daily production of each component of the web are derived from specific daily growth and gross growth efficiency measurements. The flow of biomass from secondary production to fish is sufficient to supply the food requirements of planktivorous pelagic fish and benthivorous demersal fish. Piscivorous pelagic fish obtain much of their food requirements from outside the North Sea. The food requirements of piscivorous demersal fish also do not appear to be adequately supplied from within the North Sea, but, in this case, immigration is not thought to provide the shortfall. The high predation pressure on demersal piscivores may explain why this group appears to be especially vulnerable to fishing. The supply of biomass from primary production to secondary producers appears to be sufficient without the need to postulate import into the North Sea. Indeed, the supply to the benthos is such that a detritivore trophic level can be inserted between organic settlement and production of macrobenthos

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“…Since only 1 sample was taken in the morning, diurnal migration could not be estimated. The young copepodite-stages do not migrate if the food supply is sufficient; they migrate only when the food is depleted (Krause and Trahms, 1982), as was the case during the final period beginning around March 30. Thereafter, increasing numbers of copepodite-stages were also found at 35 m.…”

Section: Periodmentioning

confidence: 99%

Nutrient and plankton development in Rosfjorden and enclosed ecosystems captured from changing water bodies during POSER

Kattner¹,

Hammer²,

Eberlein³

et al. 1983

Mar. Ecol. Prog. Ser.

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During POSER (Plankton Observations with Sinlultaneous Enclosures in Rosfjorden) in spring 1979, nutrient and plankton development were investigated in an open south Norwegian fjord and in different enclosures. Enclosures were plastic tubes, 1 m in diameter and up to 40 m long, fastened to a central float. The water in the fjord exchanged several times. This could be well documented also by changes in nutrient, phyto-and zooplankton concentrations. Water with different plankton and nutrient concentrations was enclosed in order to exclude advective processes. The experiment was divided into 3 main periods. In the first period the water in the fjord was haline. nutrient-rich, and slightly stratified, due to a bloom of Skeletonema costaturn. During this phase the phytoplankton disappeared in the fjord and in the enclosures within 6 d, likely due to low light intensities. In the second period, following a water exchange, the water was less haline, poorer in nutrients, and richer in phytoplankton (mainly Thalassiosira nordenskioeldii) and in zooplankton. Part of this water was enclosed until silicate and phytoplankton concentrations became depleted and the major zooplankton species. Calanus finmarchicus, had developed to the third copepodite-stage. In the third period, following a new upwelling of haline and nutrient-rich water up to 10 m depth, 1 enclosure was filled with well-stratified water, nutrient-poor in the upper layer, but nutrient-rich below. In spite of sufficient nutrients the phytoplankton biomass decreased in this enclosure as well as in the fjord. This was partly caused by increasing numbers of copepodites, which reached more than 50 '10 of the phytoplankton biomass during the last 8 d of our observations.

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Vertical distribution of copepods (all developmental stages) and other zooplankton during spring bloom in the fladen ground area of the north sea

Cited by 22 publications

References 9 publications

Stage-specific mortality of Calanus finmarchicus, Pseudocalanus elongatus and Oithona similis on Fladen Ground, North Sea, during a spring bloom

Stage-specific mortality of Calanus finmarchicus, Pseudocalanus elongatus and Oithona similis on Fladen Ground, North Sea, during a spring bloom

Seasonal variation in the consumption of food by fish in the North Sea and implications for food web dynamics

Nutrient and plankton development in Rosfjorden and enclosed ecosystems captured from changing water bodies during POSER

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