Continuous Plankton Records - Phytoplankton Zooplankton And Environment Northeast Atlantic And North-Sea 1958-1980

Year-to-year fluctuations in the abundance of phytoplankton in the North-East Atlantic and the North Sea for the period 1958 to 1980 are described. Based on similarities between their annual fluctuations in abundance, the taxa may be divided into two groups, one of 12 species of diatoms and 1 species of Ceratium, the other of 5 species of Ceratium. The annual fluctuations in abundance of the Ceratium group is negatively correlated with a component of sea surface temperature (representing changes in the open ocean) and with the frequency of cyclonic weather over the United Kingdom. The Diatom group shows very similar annual fluctuations to those of most of the zooplankton species. Both groups show a high ·proportion of long wavelength variability in the form of a more less linear downward trend in abundance over the whole period. There is evidence to suggest that the high proportion of long wavelength variability shown by the zooplankton is influenced by inherent persistence in stocks from year-to year. The phytoplankton show little or no persistence. The close relationship between zooplankton and phytoplankton may, therefore, involve feed-back through nutrient recycling so influencing the annual levels of abundance of phytoplankton.

Population-Dynamics And Production Of Euphausiids .2. Thysanoessa-Inermis And Thysanoessa-Raschi In The North-Sea And American Coastal Waters

Results from the Continuous Plankton Recorder (CPR) survey for 1966 and 1967 are used to describe seasonal changes in abundance, size and aspects of the population structure of Thysanoessa inermis (Krøyer) and T. raschi (M. Sars) at a depth of 10 m in the North Sea and in American coastal waters from the Grand Banks to the Gulf of Maine. Production and dry weight were estimated from these data. Two year-groups were usually present in the breeding population, the proportion surviving into a second year being higher in American waters than in the North Sea. Annual production for each species was within the range 0.69 to 4.66 mg m-3 and the ratio between production and biomass (P:B) was between 1.3 and 4.2; values outside these ranges were obtained only for American coastal waters in 1967, when the frequency of sampling was low.

Calorific Ash Carbon And Nitrogen-Content In Relation To Length And Dry-Weight Of Parathemisto-Gaudichaudi (Amphipoda Hyperiidea) In The North-East Atlantic Ocean

The calorific, ash, carbon and nitrogen content, length and dry weight were determined for the hyperiid Parathemisto gaudichaudi (Guerin). Regression equations for all these variables were determined so that they can be estimated by calculation from measurements of length of the hyperiid. Mean values for total nitrogen and carbon were 7.79±0.85% and 36.80±4.18% of the dry weight, respectively. The carbon to calorific equivalent for P. gaudichaudi was 10.37 kcal g-1 carbon (9.13 kcal g-1 when corrected for nitrogen). The calorific value for ash-free adult P. gaudichaudi was 5.138 kcal g-1±1.309 (4.510 kcal g-1 when corrected for nitrogen). This large variation in the calorific content (coefficient of variation of 25.84%) can be accounted for largely by variation in the ash content (coefficient of variation of 21.84%). The calorific value determined for P. gaudichaudi is similar to that measured for other carnivorous crustaceans and adds support to the hypothesis that animals with high calorific content have a low fecundity and an energy-rich store which can be used as a buffer during unfavourable periods in their life.