Cultivation ofCalanus helgolandicus under controlled conditions
TL;DR: The chain-forming diatomsChaetoceros curvisetus, Skeletonema costatum, Lauderia borealis and the dinoflagellateGymnodinium splendens were offered as food and the concentration of food, resembling phytoplankton concentrations found in the ocean off La Jolla, ranged from 28µG to 800µg carbon per liter.
Abstract: 1.Calanus helgolandicus was grown from egg to adult in agitated seawater cultures at 15° C in the laboratory. 2. The chain-forming diatomsChaetoceros curvisetus, Skeletonema costatum, Lauderia borealis and the dinoflagellateGymnodinium splendens were offered as food. The concentration of food, resembling phytoplankton concentrations found in the ocean off La Jolla, ranged from 28µg to 800µg carbon per liter. 3. Depending on food quality and food concentration, the time from hatching to adulthood lasts between 18 and 54 days. Mortality from hatching to adulthood ranges from 2.3% to 58.2%. The length of adult females is directly related to the amount of food offered; it ranges from 3.03 mm to 3.84 mm. 4. The sex ratio in different batches of laboratory grown copepods varies considerably. The largest percentage of males (about 25%) was obtained withLauderia borealis orGymnodinium splendens as food source. 5. The fecundity of females grown and fertilized under laboratory conditions averages 1991 eggs per female with a hatching percentage of 84%. These values are close to those obtained from spermatophore-carrying females from the ocean (2267 eggs per female; hatching percentage 77%).
Citations
More filters
TL;DR: Salinity-induced stability and shallow water favor blooms in the boundary waters of both oceans, which may be of greater importance in the Atlantic because of the proportionally greater area of continental shelf there.
Abstract: At least nine species of Calanidae occupy the area of interest, four in the Atlantic and five in the Pacific. All store wax esters and probably can undergo diapause. Latitudinally overlapping or onshore — offshore associations of two or more species occur in both oceans. Interzonals, with reduced mouth parts in the adult female, are endemic to the Pacific subarctic gyre where their life cycles are completed in one year. Presumably its nearly closed circulation and environmental stability have favored the evolution of endemic species well adapted to those conditions. Lack of ice- and/or salinity-induced stability also limits blooms there. The sub-arctic Atlantic contains several smaller oceanographic features, open to both arctic and Atlantic influences and populated by species of different origins, arctic species can behave as interzonals but may also require two or more years to complete their life cycles. Females may need to feed one year to reproduce the next and therefore they retain functional mouthparts. In some places in the North Atlantic, blooms may start in the sub-ice zone and seed the remaining euphotic zone. There the earliest stages of some the Calanus species can develop close to the ice, using primarily ice algae as food, while the remaining stages are adapted to utilize brief periods of intense primary production in the water column. Salinity-induced stability and shallow water favor blooms in the boundary waters of both oceans, which may be of greater importance in the Atlantic because of the proportionally greater area of continental shelf there. In both oceans the smaller species of Calanidae can produce up to three generations per year.
498 citations
TL;DR: Two different metabolic pools are postulate to explain the origin of these long chain alcohols - polyunsaturated alcohols of the wax esters and phospholipid fatty acids, which were not affected by changes in the amount or type of food, probably because of their structural function.
Abstract: Wax esters, which function as reserve fuels, account for 25 to 40% of the lipid of the pelagic copepod Calanus helgolandicus (Copepoda, Calanoida). In laboratory experiments with these crustaceans, diatoms (Lauderia borealis, Chaetoceros curvisetus, and Skeletonema costatum) and dinoflagellates (Gymnodinium splendens), which contained no wax esters, were used as food. Changes in the food concentration affected both the amount of lipid and the composition of the wax esters. Since the fatty acids of the triglycerides and wax esters of C. helgolandicus resembled the dietary fatty acid composition, it appeared that copepods incorporated their dietary fatty acids largely unchanged into their wax esters. The polyunsaturated alcohols of the wax esters did not correspond in carbon numbers or degrees of unsaturation to the dietary fatty acids. We postulate two different metabolic pools to explain the origin of these long chain alcohols. The phospholipid fatty acids were not affected by changes in the amount or type of food, probably because of their structural function.
377 citations
TL;DR: Multiple regression analysis of published zooplankton filtering and feeding rates yielded separate regression equations for cladocerans, marine Calanoid copepods, and all zoopLankton, which suggest possible mechanisms of feeding limitation and provide a heuristic framework for the design of experimental analyses of zoopalankton feeding in marine and freshwater systems.
Abstract: Multiple regression analysis of published zooplankton filtering and feeding rates yielded separate regression equations for cladocerans, marine Calanoid copepods, and all zooplankton. Ingestion rate was found to increase significantly with animal size, food concentration, and temperature. Filtering rate also increased with animal size and temperature, but declined as food concentration increased. The analysis suggests a difference in particle size preference between cladocerans and copepods. Experimental conditions such as crowding and duration also significantly affected filtering and feeding rates. The regression models allow examination of differences and similarities among zooplankton taxa, functional response, particle size selection, energy allocation, and threshold food concentration. The statistical models describe suspension feeding more precisely than either average literature values or verbal descriptions of trend. The results also suggest possible mechanisms of feeding limitation and provide a heuristic framework for the design of experimental analyses of zooplankton feeding in marine and freshwater systems.
362 citations
TL;DR: It is postulated that species of zooplankton seem to be geographically and vertically distributed, in relation to body size and food availability, to optimize growth rates at various stages of their life cycles.
Abstract: Changes in dry weight and in weight-specific growth rates were measured for copepodite stages of Calanus pacificus Brodsky and Pseudocalanus sp. cultured under various combinations of phytoplankton concentration and temperature. Mean dry weight of early copepodites was relatively unaffected by either food concentration or temperature, but mean dry weight of late stages increased hyperbolically with food concentration and was inversely related to temperature. The food concentration at which maximum body weight was attained increased with increasing temperature and body size, and it was considerably higher for C. pacificus than for Pseudocalanus sp. This suggests that final body size of small species of copepods may be determined primarily by temperature, whereas final body size of large species may be more dependent on food concentration than on temperature. Individual body weight increased sigmoidally with age. The weight-specific growth rate increased hyperbolically with food concentration. The maximum growth rate decreased logarithmically with a linear increase in body weight, and the slope of the lines was proportional to temperature. The critical food concentration for growth increased with body size proportionally more at high than at low temperature, and it was considerably higher for C. pacificus than for Pseudocalanus sp. Because of these interactions, early copepodites optimized growth at high temperature, even at low food concentrations, but under similar food conditions late stages attained higher growth at low temperature. The same growth patterns were found for both species, but the rates were significantly higher for the larger species, C. pacificus, than for the smaller one, Pseudocalanus sp. On the basis of findings in this study and of analyses of relationships between the maximum growth rate, body size, and temperature from other studies it is postulated (1) that the extrapolation of growth rates from one species to another on the basis of similarity in body size is not justified, even for taxonomically related species; (2) that the allometric model is inadequate for describing the relationship between the maximum weight-specific growth rate and body size at the intraspecific level; (3) that the body-size dependence of this rate is strongly influenced by temperature; and (4) that species of zooplankton seem to be geographically and vertically distributed, in relation to body size and food availability, to optimize growth rates at various stages of their life cycles.
335 citations
TL;DR: It is recommended that secondary production rates of Calanus finmarchicus and possibly other lipid-storing copepods not be estimated from egg production mea- surements alone, as has been suggested for other species of copepod, because growth, including structural growth, is not equivalent for all stages.
Abstract: Development rates, nitrogen- and carbon-specific growth rates, size, and condition were determined for the copepod Calanus finmarchicus reared at 3 temperatures (4, 8, and 12°C) at non-limiting food concentrations and 2 limiting food concentrations at 8°C in the laboratory. Devel- opment rates were equiproportional, but not isochronal. Naupliar stage durations were similar, except for non-feeding stages, which were of short duration, and the first feeding stage, which was prolonged, while copepodite stage durations increased with increasing stage of development. Under limiting food concentrations at 8°C, development rates were prolonged but similar relative patterns in stage durations were observed. Body size (length and weight) was inversely related to temperature and positively related to food concentration. Condition measurements were not affected by tempera- ture, but were positively related to food concentration. Growth rates increased with increasing tem- perature and increased asymptotically with increasing food concentration. At high food concentra- tions, growth rates of naupliar stages were high (except for individuals molting from the final naupliar stage to the first copepodite stage, in which growth rates were depressed), while growth of copepodites decreased with increasing stage of development. Neither nitrogen nor carbon growth rates, the former a proxy for structural growth, were exponential over the entire life cycle, but rather sigmoidal. Carbon-specific growth rates were greater than nitrogen-specific growth rates, and this difference increased with increasing stage of development, reflecting an augmentation in lipid depo- sition in the older stages. However, nitrogen and carbon growth rates were more similar under food- limited conditions. Based on this study, we recommend that secondary production rates of Calanus finmarchicus and possibly other lipid-storing copepods not be estimated from egg production mea- surements alone, as has been suggested for other species of copepods, because growth, including structural growth, is not equivalent for all stages.
321 citations
References
More filters
TL;DR: In this article, the organic carbon in phytoplankton from cell volume or plasma volume is derived from original data on five species of diatoms and from data in the literature.
Abstract: Equations for estimating the organic carbon in phytoplankton from cell volume or plasma volume are derived from original data on five species of diatoms and from data in the literature. Differences among species are important sources of error in such estimates. Plasma volume provides a more precise estimate of cell carbon in diatoms than does cell volume. Diatoms, because of their lower carbon per cell volume, should probably be treated separately from other phytoplankton in such computations.
1,311 citations
TL;DR: In this paper, a method for the rapid determination of dissolved organic carbon in seawater in concentrations between 0.1 and 20 mg/liter was described, which was carried out in sealed glass ampoules using K 2 S 2 O 8 as an oxidizing agent after the sample has been freed of inorganic carbon.
Abstract: A method is described for the rapid determination of dissolved organic carbon in seawater in concentrations between 0.1 and 20 mg/liter. The oxidation is carried out in sealed glass ampoules using K 2 S 2 O 8 as an oxidizing agent after the sample has been freed of inorganic carbon. The resulting CO 2 is passed through a nondispersive infrared analyzer using nitrogen as a carrier and the signal output of the analyzer recorded. Using appropriate calibration curves, the carbon content is determined from the height of the peak. Approximately 100 samples can be analyzed in a single day with a precision of ± 0.1 mg/liter using a sample volume of 5 ml. A companion method is described for the determination of particulate carbon by high-temperature combustion after concentration of the sample on a glass-fiber filter. The precision of this method is ± 10 mug C in a range of 0-500 mug C. Approximately six samples can be analyzed in an hour.
857 citations
TL;DR: Rhincalunus nusutus nauplii was cultured through seven consecutive generations in 19-liter carboys when provided with a mixture of diatoms and Artcnzia salina nauPLii as food, and the suggestion that the copepods' first antennae are used in the feeding process was not supported.
Abstract: Rhincalunus nusutus was cultured through seven consecutive generations in 19-liter carboys when provided with a mixture of diatoms and Artcnzia salina nauplii as food. The mean generation length was 8.7 weeks, similar to that of the local field population of this species during some seasons. Fecundity of laboratory-reared animals was lower than that of the field population. Instantaneous coefficients of individual exponential growth ( k in the expression, Wt = Woekt,where W is body weight of organic carbon and t is days) were 0.24 to 0.12/day, depending on the age of the individual. About 10 pg of detrital carbon were produced as exuviae during the growth of an individual. Even young nauplii fed preferentially on large food particles. The suggestion that the copepods' first antennae are used in the feeding process was not supported by an experimental test. R. nusutus nauplii are apparently active enough to avoid being eaten by their parents.
179 citations
TL;DR: In the female there is a pair of diverticula extending from the proximal end of the oviduct into the head region, and into this the developing eggs pass as mentioned in this paper.
Abstract: Comparatively little is known about the factors affecting egg-laying in Calanus. Deductions from work in the field have been made by Nicholls (1933a, b) and Marshall, Nicholls & Orr (1934), and experimental work in the laboratory has been done by Raymont & Gross (1942).Emgg-LayingInCalanusThe anatomy of the reproductive system has been described in detail by Lowe (1935). In the female there is a pair of diverticula extending from the proximal end of the oviduct into the head region, and into this the developing eggs pass. Each diverticulum has a dorsal and a ventral channel, and the eggs pass from the dorsal into the ventral channel and then into the oviduct proper. The oviduct rises from the forward end of the ovary and crosses the body laterally and ventrally so that a short part of it can be clearly seen.
148 citations
TL;DR: The results indicate that the large standing stock of zooplankton which developed in the vicinity of the Fraser River estuary resulted from the presence of adequate concentrations of the right size and shape of food organisms and from a lack of severe predation on the early growth stages of this copepod.
120 citations