Gymnodinium blooms in the Helgoland bight (North Sea) during August, 1968

Hickel, Wolfgang; Hagmeier, Erik; Drebes, G.

doi:10.1007/bf01611127

Cited by 25 publications

(10 citation statements)

References 21 publications

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“…Figs, IC and 2 c), but there is no evidence from field observations that G. aureolum exhibits diurnal migrations. Although the abundance of this species in the late summer and autumn (also see Braarud & Heimdal, 1970;Hickel, Hagmeier & Drebes, 1971) suggests that dissolved organic substances may be important for its nutrition, the chemical data for El on 12 August (Table 2) and observations on the Ushant frontal system indicate that some input of inorganic nutrients is also a prerequisite for optimal growth conditions. On 12 August oxygen levels at 5 m exceeded 170% saturation.…”

Section: August {Table 6 Fig 2c)mentioning

confidence: 97%

The vertical distribution and succession of phytoplankton in the western English Channel in 1975 and 1976

1977

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Changes in levels of chlorophyll' a' and phaeopigments and in the species composition of phytoplankton populations at station Ei during the summer months are described. After the spring diatom outburst in April, diatoms continue to be abundant during May, first in the surface water and then below the thermocline. From June to August dense populations of dinofiagellates in the thermocline are the dominant feature. In September diatoms are again abundant as the thermocline is eroded. Factors controlling the growth of these different algal communities, including grazing, are discussed. P. M. HOLLIGAN AND D. S. HARBOUR III fluorometer was used to detect chlorophyll ' a ' fluorescence. The time delay between water entering the hose and reaching the flow cell of the fluorometer was 60-90 s, depending on the length of hose in use. The hose inlet was raised or lowered at a rate of 2 m min" 1 for routine observations, and mixing within the hose tended to smooth out any sharp discontinuities in chlorophyll fluorescence. Thus, whenever the hose inlet was held at the depth of subsurface maxima, maximum fluorescence values were higher by as much as 50 % than those observed in normal profiles.Plant pigments in discrete filtered samples were determined spectrophotometrically (Strickland & Parsons, 1972). The filters were placed immediately in 90 % acetone or stored for as short a time as possible (generally < 24 h) in the dark at -20 °C prior to extraction. Where appropriate, corrections were made to chlorophyll' a' values for interference by phaeopigment. Rates of carbon dioxide fixation were determined as described by Pingree et al. (1976).Water samples for phytoplankton counts were collected by bottle or from the outflow of the fluorometer and preserved with Lugols Solution (10 g I + 20 g KI in 200 ml distilled water + 20 ml glacial acetic acid) at a final concentration of 0-5 %. Cell counts were made by UtermohPs inverted microscope technique (Lund, Kipling & Le Cren, 19585 Lovegrove, i960), using a Wild M40 microscope that was fitted with phase contrast equipment, at magnifications of x 187, x 375 and x 750. Each organism was identified to the lowest possible taxonomic rank and nomenclature follows the check lists of Hendey (1974) for diatoms and Parke & Dixon (1976) for other algal groups. Authorities are given only for diatom species that are not listed by Hendey. The category ' flagellates' includes all cells that had recognizable flagella and/or plastids (excluding dinoflagellates and diatoms), and was dominated by forms with a mean diameter in the range 2-10 finx. A copy of the complete taxonomic data has been deposited for reference in the library of the Marine Biological Association.The volume of samples used for sedimentation varied between 50 and 265 ml, according to the overall abundance of phytoplankton as shown by the fluorometer response. At least 100 cells of each of the more abundant species were enumerated and, to obtain some measure of accuracy for the counting procedure, 10 sub-samples of a larger, well ...

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Section: August {Table 6 Fig 2c)mentioning

confidence: 97%

The vertical distribution and succession of phytoplankton in the western English Channel in 1975 and 1976

1977

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“…The first report of this species dates back to 1966, when it formed a spectacular bloom in Norwegian waters (Braarud & Heimdahl, 1970). A second bloom occurred in 1968 in the southern German Bight (Hickel et al, 1971). Since then, blooms have been reported regularly in different parts of the North Sea and the Atlantic off England and France.…”

Section: Dinoflagellates: Exoticsmentioning

confidence: 98%

Exotic flagellates of coastal North Sea waters

Elbrächter

1998

Helgolander Meeresunters

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Flagellate species have been shown to survive transocean passage by ballast water and the large dinoflagellate Gymnodinium catenatum was introduced from Japanese to Tasmanian waters in this way. Gymnodinium mikimotoi -better known as Gyrodinium aureolum -and Fibrocapsa japonica as well as Alexandrium leeii are good candidates to have been introduced recently. Species which seem to have been introduced recently into the North Sea but apparently are transported from adjacent seas by currents into the region are Gymnodinium chlorophorum and Alexandrium rninutum.

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“…A well known example is the fish-toxic species Gyrodinium aureolurn, which was found for the first time in 1966 in Norway and 1968 in the German Bight (HICKEL et al 1971). In these cases, it can be assumed that these species immigrated or were introduced.…”

Section: Data Situationmentioning

confidence: 99%