The large-scale circulation in the Skagerrak; interpretation of some
                        observations

Rodhe, Johan

doi:10.3402/tellusa.v39i3.11757

Cited by 50 publications

(62 citation statements)

References 2 publications

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“…< 100 m. Eisma & Kalf (1987) found that suspended matter concentrations in the bottom water are similar to those in the surface and that velocity of the currents going into Skagerrak can be up to 15 cm S-' down to 100 m water depth (Rodhe 1987). It can be noted that an unbalance between carbon input and respiration has also been found by others, e.g.…”

Section: Sedimentation and Respirationmentioning

confidence: 67%

Pelagic nutrient and energy transfer during spring in the open and coastal Skagerrak

Rosenberg¹,

Dahl²,

Edler³

et al. 1990

Mar. Ecol. Prog. Ser.

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In May 1987 multidisciplinary investigations focusing on die1 variations were performed at 4 horizontally stratified (pycnocline at 5 to 12 m) stations in the open Skagerrak (North Sea). Nutrients were lower above the pycnocline than below. Phytoplankton was numerically dominated by flagellates and monads indicating a regenerating plankton community, which was confirmed by the finding that about 80 % of the nitrogen uptake in surface waters was as NH4+ and urea, and about 20 O/O was N o 3 -Percentage of 'new' primary production (based on NOII-uptake) was similar to the percentage sedimentation rate (in C) of primary production (ca 20%). Growth of bacteria and grazing on bacteria were systematically dependent on time of day above, in and below the pycnocline. Abundance of bacteria and nanoflagellates was not regularly dependent on time of day, but systematically elevated in the pycnocline, as was chlorophyll a. Zooplankton grazing in the surface water was highest at night and early morning. Benthic investigations indicated heterogeneity in the area For comparison, samples of hydrography, nutrients, phytoplankton abundance and growth, and sedimentation were investigated at the same bme at a coastal station with horizontal stratification and slightly lower salinity. Here 'new' primary production was estimated to about 50 % of total production, based on percentage sedimentation. Nitrogen seemed in general to be in deficit for primary production relative to phosphorus in surface waters both in the open and coastal Skagerrak, but exceptions could occur That nutrients were in surplus just below the shallow pycnocline shows, however, that those primary producers and bacteria whi.ch could utilize this reservoir had access to unlimited nutrient resources at that time. It was estimated that bacteria and flagellates made up > 5 0 % of total pelagic respiration and consumed slightly more than the net primary production.

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Section: Sedimentation and Respirationmentioning

confidence: 67%

Pelagic nutrient and energy transfer during spring in the open and coastal Skagerrak

Rosenberg¹,

Dahl²,

Edler³

et al. 1990

Mar. Ecol. Prog. Ser.

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“…Two major current systems affect the coastal area; the Baltic Current runs north, parallel to the coast, bringing low salinity surface water, whereas more saline water from the North Sea and Atlantic Ocean flows through the Skagerrak towards the Swedish coast in the Jutland Current. Hence, the coastal water is stratified in terms of salinity, and a pronounced halocline is present (Rodhe 1987, Lindahl 1995. The coastline has a variety of fjord systems.…”

Section: Methodsmentioning

confidence: 99%

Influence of benthic and pelagic environmental factors on the distribution of dinoflagellate cysts in surface sediments along the Swedish west coast

Godhe¹,

McQuoid²

2003

Aquat. Microb. Ecol.

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Abundance and frequency of dinoflagellate cysts in 19 surface sediment samples from the northern part of the Swedish west coast has been related to physical and chemical characters of the sediment, hydrography of the overlying water column, and plankton species data from the area. Density of cysts varied between 5000 and 101 000 cysts g -1 dw, and the most commonly encountered species were Lingulodinium polyedrum and Protoceratium reticulatum. In all, 46 environmental variables were tested for their relation to dinoflagellate cyst densities, proportion of autotrophic and heterotrophic taxa, and individual species distribution and frequency. The outcomes of multivariate analyses, projection to latent structures (PLS) and canonical correspondence analysis (CCA) were consistent with each other and the actual cyst count. The density of the total cyst assemblage (> 90% autotrophic taxa) was primarily related to surface temperature, macronutrients, and inversely to phytoplankton competitors, such as diatoms. The abundance of heterotrophic taxa was governed by the preferences of their prey, i.e. diatom-favourable conditions, and, in most cases, higher proportions of heterotrophic taxa were found at well-mixed sites. Some possible effects of anthropogenic contaminants were also noted. Several taxa showed distinct distribution patterns with respect to the environmental variables. A discrepancy between the species constituting the planktonic and the benthic community was revealed when data from 6 yr of plankton monitoring was compared to the data on distribution of dinoflagellate cysts. In particular, cyst-forming species were only a minor part of the plankton, suggesting that these dinoflagellates spend much of their life in the sediments. KEY WORDS:Cysts · Dinoflagellate · Dinophyceae · Surface sediment · CCA · PLS · Environmental factors Resale or republication not permitted without written consent of the publisher

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“…Two major current systems affect the Skagerrak coastal area: the low saline surface Baltic current running north parallel to the coast, and the central Skagerrak water circulation pattern resulting in an inflow of more saline North Atlantic water. Hence, the coastal water is stratified in terms of salinity and a pronounced halocline is present (Rodhe 1987, Lindahl 1995. Within Nycklebyviken is a blue mussel farm of approximately 4500 m 2 (Fig.…”

Section: Methodsmentioning

confidence: 99%

Oceanographic settings explain fluctuations in Dinophysis spp. and concentrations of diarrhetic shellfish toxin in the plankton community within a mussel farm area on the Swedish west coast

Godhe¹,

Svensson²,

Rehnstam-Holm³

2002

Mar. Ecol. Prog. Ser.

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The influence of hydrographic, biological and meteorological variables on the abundance of Dinophysis spp. and the concentration of diarrhetic shellfish toxin (DST) in the plankton population were investigated in a mussel (Mytilus edulis) farm area on the Swedish west coast. This location provided an opportunity to simultaneously compare Dinophysis spp. cell numbers, concentration of DST in natural phytoplankton assemblages and toxicity of mussel tissues. Sampling was performed every other day from October 10 to November 5, 2000, and on each occasion, 5 randomly selected sites were sampled. During this period, 3 distinct water masses passed through the vicinity of the mussel farm. The second water mass, characterized by low salinity and nitrogen concentration, was probably advected into the area from surface waters in the nearby Skagerrak. This low salinity water also contained a high abundance of Dinophysis spp., and high concentrations of DST were recorded in the phytoplankton population. Multivariate analysis (projection to latent structures by means of partial least squares, PLS) determined that the principal variables influencing the concentration of DST in the plankton assemblage were the causative species (D. acuminata, D. acuta and D. norvegica) and salinity. The abundance of the 3 Dinophysis spp. was inversely correlated to salinity. A rapid increase in the toxicity of mussels in response to the high levels of DST was observed. The concentration of DST had doubled within 2 d of the appearance of Dinophysis spp. After 8 d, the water mass containing Dinophysis spp. was replaced and cell numbers again returned to low levels. The concentration of DST in the phytoplankton samples remained high for another 2 d after the number of Dinophysis spp. had declined and the toxicity of mussels continued to be high for the remainder of the study. Causes of the rapid intoxication versus slow detoxification of mussels are discussed. These results suggest that present monitoring programs are insufficient to provide early warning of toxic blooms to aquaculturists on the Swedish west coast.

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The large-scale circulation in the Skagerrak; interpretation of some observations

Cited by 50 publications

References 2 publications

Pelagic nutrient and energy transfer during spring in the open and coastal Skagerrak

Pelagic nutrient and energy transfer during spring in the open and coastal Skagerrak

Influence of benthic and pelagic environmental factors on the distribution of dinoflagellate cysts in surface sediments along the Swedish west coast

Oceanographic settings explain fluctuations in Dinophysis spp. and concentrations of diarrhetic shellfish toxin in the plankton community within a mussel farm area on the Swedish west coast

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