Continuous Plankton Recorder Samples Research Articles

A change in the zooplankton of the central North Sea (55* to 58* N):a possible consequence of changes in the benthos

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 119:299-303 (1995) - doi:10.3354/meps119299 A change in the zooplankton of the central North Sea (55* to 58* N): a possible consequence of changes in the benthos Lindley, J. A., Gamble, J. C., Hunt, H. G. The mesozooplankton taken in continuous plankton recorder samples from the central North Sea has changed from being numerically dominated by holoplanktonic calanoid copepod species from 1958 to the late 1970s to a situation where pluteus larvae of echinoid and ophiuroid echinoderms have been more abundant than any single holoplanktonic species in the 1980s and early 1990s. The abundance of the echinoderm larvae as a proportion of the zooplankton taken in the samples has followed a continuous increasing trend over the Dogger Bank, but off the eastern coast of northern England and southern Scotland the increase did not become obvious until the 1980s. This trend is consistent with reported increases in abundance of the macrobenthos. It is proposed that changes in the benthos have influenced the composition of the plankton. Holoplankton . Meroplankton . Macrobenthos . Echinoderm . Larvae . North Sea Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 119. Publication date: March 23, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.

Anomalous seasonal cycles of decapod crustacean larvae in the North Sea plankton in an abnormally warm year

In 1989 the seasonal cycles of most common decapod larvae in Continuous Plankton Recorder samples taken in the North Sea were significantly different from those described for 1947–1951 and for 1981–1983. In all cases where the differences were significant the larvae occurred earlier in 1989 than in previous years. Zoeae of Atelecyclus rotundatus were found in the Southern Bight in the spring. The winter of 1988–1989 was exceptionally mild with air temperatures over Great Britain 2–3 °C above average and positive temperature anomalies persisted through the year. The sea surface temperatures in the North Sea were also mainly higher than usual. The events were treated as a “natural experiment” to examine effects of the high temperatures on seasonal cycles of decapod larval production and the implications of these effects for marine communities with reference to predicted global warming. The relationships between timing of occurrence of the larvae in the plankton and parameters of sea temperatures were generally consistent with previous results from studies of geographical variations, and possible causal mechanisms are discussed in the light of the 1989 data.

Doliolids in the German bight in 1989: Evidence for exceptional inflow into the North Sea

Doliolids were found in samples taken with a Continuous Plankton Recorder (CPR) in October 1989 between 55°14'N 03°32'E and 55°20'N 06°13'E during a tow between Newcastle and Esbjerg. Densities were estimated at >100 m−3 for about 112 km of tow. A sub-sample of specimens in sufficiently good condition to be reliably identified were referred to Doliolum nationalis Borgert. Substantial numbers of doliolids were found on a CPR tow between Harwich and Gothenburg which passed through the same area in that month and specimens were found nearer to the Danish coast in November and south-west of Helgoland in December. The distribution of doliolids in CPR samples taken in the North Sea in the last three months of 1989 is shown in Figure 1.

Long-term trends in the distribution, abundance and seasonal occurrence of larvae of mackerel (Scomber scombrus L.) around the British Isles, 1948–1978

The distribution, abundance and seasonal occurrence of larvae of mackerel (Scomber scombrus L.) are described from routine Continuous Plankton Recorder (CPR) sampling around the British Isles over the period 1948–78, and from more intensive CPR sampling in the Celtic Sea in 1977. There were two main areas of larval concentration: in the North Sea and over and adjacent to the Celtic Plateau; subsidiary aggregations were observed to the northwest of Ireland and to the west of Norway. There were some similarities between the distribution of larvae around the British Isles and that of adult Calanus spp. In the North Sea there was a southerly shift of larval distribution over the period 1948–77; over a similar period the abundance of larvae increased to reach high numbers by the late 1950s and subsequently declined after the mid-6os. To the south-west of the British Isles numbers of larvae showed a long-term decline. The long-term trends of distribution and abundance are discussed in relation to concurrent biological and environmental change. The clearest relationship was found between the numbers of mackerel larvae in the North Sea and sea-surface temperature in the North Atlantic, which suggests a common causative agent for both sets of observations; also, there was a weak relationship with both spawning stock biomass and sea-surface temperature at the spawning areas. In the North Sea the seasonal occurrence of larvae was from May to August, the majority being taken in June and July; over the period 1948–77 the seasonal time of occurrence of highest numbers of larvae has remained relatively constant. In the Celtic Sea the seasonal occurrence of larvae was spread over a longer period, from March to August, with relatively high numbers from March to June; over the period 1950–78 the time of occurrence has been variable, possibly with a tendency towards later timing in more recent years.