Modelling the basin-scale demography of Calanus finmarchicus in the north-east Atlantic

In this paper, we report on a coupled physical–biological model describing the spatio-temporal distribution of Calanus finmarchicus over an area of the North Atlantic and Norwegian Sea from 56°N, 30°W to 72°N, 20°E. The model, which explicitly represents all the life-history stages, is implemented in a highly efficient discrete space–time format which permits wide-ranging dynamic exploration and parameter optimization. The underlying hydrodynamic driving functions come from the Hamburg Shelf-Ocean Model (HAMSOM). The spatio-temporal distribution of resources powering development and reproduction is inferred from SeaWiFS sea-surface colour observations. We confront the model with distributional data inferred from continuous plankton recorder observations, overwintering distribution data from a variety of EU, UK national and Canadian programmes which were collated as part of the Trans-Atlantic Study of Calanus (TASC) programme, and high-frequency stage-resolved point time-series obtained as part of the TASC programme. We test two competing hypotheses concerning the control of awakening from diapause and conclude that only a mechanism with characteristics similar to photoperiodic control can explain the test data.     

The multinomial logit model: a new tool for exploring Continuous Plankton Recorder data

The use of Generalized Additive Models in the analysis of Continuous Plankton Recorder (CPR) distribution and abundance data for C alanus finmarchicus and C. helgolandicus is demonstrated. Strong emphasis is placed on the influence of long-term trend, seasonality and location. The preponderance of zeros in the data, as well as the particular problems associated with the CPR recording protocol, are adequately handled by the models. Three models are described. In the first two, data within arbitrary spatial compartments are modelled as smooth functions of long-term trend and seasonality, assuming a spatial homogeneity within the area. In the third model, the spatio-temporal distributions of abundances over the North Sea in specific months each year are modelled as a three-dimensional smooth function of long-term trend and location (latitude and longitude). The summaries produced by the models reveal dynamic seasonal, spatial and long-term patterns of abundance, many of which have not been revealed by the previous analytical techniques employed.     

Oil extraction From the Copepod Calanus finmarchicus Using Proteolytic Enzymes

The limited amount of fish oils available has led to extensive search for alternative sources of oils rich in long-chain n-3 polyunsaturated fatty acids (PUFA). The zooplankton Calanus finmarchicus is present in large amounts in the North Atlantic and have lipid-rich stages which can be harvested. The main objective of this study was to investigate if the use of food grade proteolytic enzymes, Alcalase® and Flavourzyme®, could improve oil recovery in an industrial-like process, and to characterize the oil obtained. The results showed a substantially higher oil yield with the use of proteolytic enzymes compared to standard fish oil production technology. The oil from C. finmarchicus had a high content of n-3 PUFA mainly comprised of stearidonic acid (18:4 n-3), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Wax esters were the dominating lipid class in the oil.     

渤海中华哲水蚤桡足幼体摄食的初步研究

对３４２个含有食物的消化道分析结果表明，中华哲水蚤桡足幼体营浮游植物食性，主要摄食硅藻类，其中辐圆筛藻，未查明的圆筛藻和星脐圆筛藻是它的主要摄食对象对象。它在渤海所食物类群，几科没有季节变化，四季都以硅藻类居绝对优势，食物类群更替率各季平均只有０．５％。它所摄食的食物种类则有一定的季节变化，食种类更替率各季平均为１２．７％。它的摄食强度以冬季为最高，春，夏次之，秋季最低，它对环境中的饵料浮游植物有     

Population dynamics of Calanus chilensis in the Chilean Eastern Boundary Humboldt Current

A study of the population dynamics of Calanus chilensis was carried out in the coastal area of the Mejillones Peninsula (23°S), which is an upwelling site in the Eastern Boundary Humboldt Current. Information was derived from time-series sampling (15 day interval) at three stations, and from two broad-scale cruises: under active upwelling, and under 1997/1998 El Niño conditions. Calanus chilensis showed continuous reproduction throughout the year. In the study area, upwelling takes place intermittently year-round, suggesting that Calanus production is not limited by food. Advection played an important role in structuring the spatial distribution of Calanus , both during upwelling and under El Niño conditions. Population losses from upwelling and offshore transport may be compensated by rapid turnover rates of cohorts, growing at temperature-dependent rates and hence allowing population recovery, even in abnormally warm waters during El Niño conditions.     

The spring/early summer distribution of Calanus spp. in the northern North Sea and adjacent areas

The spring/early summer distribution of Calanus spp. in the north-eastern Atlantic and the northern North Sea was studied from data collected on three cruises between 1992 and 1995, and compared against estimates from Continuous Plankton Recorder (CPR) data obtained between 1958 and 1993. The patterns observed in both data sets were examined in relation to the hypothesis proposed by Backhaus et al . (1994 ) to explain the annual spring invasion of the northern North Sea by Calanus finmarchicus . The results confirmed that arrival of Calanus spp. in the northern North Sea started in March. The main routes of transport into the area were the Norwegian Trench Atlantic Inflow and East Shetland Atlantic Inflow. The highest abundances of Calanus spp. juveniles (stages CI–IV) were found in May in both CPR and cruise data. Although significant differences in absolute abundance of Calanus spp. were found between CPR and cruise data, similar geographical and temporal patterns of spring advection into the North Sea were derived from both data sources, these patterns being consistent with the hypothesized transport mechanisms.