Temora Stylifera Research Articles

Remarques sur la structuration des populations zooplanctoniques dans la zone de l'�missaire de Marseille-Cortiou

The impact of a polluted water-layer on zooplanktonic populations was studied in the sewage discharge zone at Marseille-Cortiou throughout 1977 and a modification of specific diversity was observed: diversity was instable near the outfall, but increased slightly and became more stable further away in non-polluted stations. The population composition did not seem to change. Species rank varied slightly and the number of species increased with increasing distance from the outfall. Specific “dominance” remained relatively unchanged, and essentially consisted of only 5 species: Clausocalanus acuicornis, Evadne spinifera, Oithona helgolandica, Temora stylifera and Centropages typicus. The population structure, as illustrated by “Frontier” diagrams, was higher during or just preceding winter. Population organisation was the same close to or far away from the outfall, although the total population counts and number of species were smaller at the most polluted stations. The taxons exhibiting the largest decreases in density were: euphausids, nauplii, larvae of various brachyurans and gastropods, fish eggs, the pteropod Cavolinia inflexa, the copepod Calanus minor and several Coryceidae. The greatest disturbance of the population structure at all stations was observed during the summer. The composition of the zooplanktonic population seems to depend much more on seasonal factors than on the level of pollution. In was not possible to distinguish a cluster of species which were sufficiently dominant to be considered as really characteristic; perhaps the rather high exposure of the sewage site to winds and waves prevents the formation of a local facies.

Étude de la ponte et du développement embryonnaire en relation avec la température et la nourriture chez Temora stylifera Dana (Copepoda:Calanoida)

Egg production by the copepod Temora stylifera was significantly influenced by the algal composition of the diet. Egg production was higher with Hymenomonas elongata as food than with Phaeodactylum tricornutum, Skeletonema costatum or a mixture of the three species. Egg production increased also with concentration of food reaching a maximum of 277 ± 20 eggs per female in 7 days. The parameters of the equation describing this relation: γ = α(1−e t ̄ βχ ) + c were calculated for Temora stylifera fed Hymenomonas elongata. Egg production was measured in terms of carbon and nitrogen; it reached 131 % of the body weight of the adult in carbon and 53% of its body weight in nitrogen per 7 days. Influence of food and season on egg was also shown. Temperature had also a direct influence on egg production, with an optimum at 16°C (mean temperature in situ). The seasonal temperature in situ at which the female copepod matured, seemed to influence the acute response of egg production to temperature. Seasonal variations in egg production were shown with a maximum in autumn and a decrease in winter and spring corresponding with seasonal fluctuations in the adult population and the chlorophyll concentration in the sea. An equation was fitted to the eggs development time (hatching) versus temperature: D = α( T− α) b . The parameters of that equation were shown to vary in relation to the initial in situ temperature. The data suggested that the acclimation of females to ambient temperature might be transmitted to the maturing eggs before spawning.

Comparaison biochimique de quatre esp�ces de cop�podes planctoniques de M�diterran�e nord-occidentale � partir des enzymogrammes des est�rases, de la leucine aminopeptidase, de la phosphatase alcaline, de la malate d�shydrog�nase et de l'enzyme malique

Four copepod species (Acartia clausi, Centropages typicus, Temora stylifera, Calanus helgolandicus) from the northwest Mediterranean were subjected to electrophoresis on polyacrylamide gel in an attempt to distinguish specific biochemical characteristics for each species. Enzymograms of 5 enzymes were studied: esterases, leucine aminopeptidase, alkaline phosphatase, malate dehydrogenase and the malic enzyme. Marked interspecific differences were revealed, enabling specific biochemical identities to be established which can be useful as taxonomic criteria in the same way as morphological characteristics. The study was performed during different seasons in 1980.

On the feeding of copepods on Thalassiosira partheneia from the Northwest African upwelling area

Copepod feeding on the colony-building diatom Thalassiosira partheneia was studied in spring 1975 in the Northwest African upwelling area. Healthy, whole colonies of T. partheneia (diameter 1 cm) were offered as food as well as single cells (diameter 9 pm) after disintegration of the colonies. In addition, comparative experiments were carried out with the dinoflagellate Scrjppsiella trochoidea. None of the 13 copepod species studied was able to feed on the entire colony. However, feeding on single cells after disintegration of the colonies was found for 4 copepod species studied. The actual quantity of food intake ranged from 14.7 to 124.0 % body carbon per day. The lowest values were obtained for Calanus helgolandicus, the highest for Temora stylifera

Physioecology of Tropical Marine Copepods. I. Size Variations')

Size variations of two species of copepods collected off the west coast of Barbados were determined on an approximate fortnightly basis over a study period of two years. The observed variations were random rather than regularly recurring based on seasons and appeared not to be linked to temperature. Attempts were made to correlate prior food supply with present size. Some positive correlations between phytoplankton numbers and zooplankton dry weights and respective sizes of female Temora stylifera and Oncaea mediterranea were established. The male of the latter showed no size-food relationship. The results are discussed in the context of the theory of r and K selection. It was concluded that the reproductive strategies are a compromise between two conflicting demands, namely production of the largest possible clutch size (r selection) and achieving highest possible individual fitness (size) of the offspring (K selection).

Zooplanktonic Communities of the Divergence Zone in the Northwestern Alboran Sea

Abstract. Using principal component analysis, the zooplanktonic communities of the divergence zone in the northwestern sector of the Alboran Sea were studied. The study was based on 35 vertical trawls in the 200 metres superficial level. The two first components account for 65 % of the total variance. The first component is a contrast between a warm water coastal community (characterized by low specific diversity and the abundance of Cladocera and Copepoda such as Acartia clausi, Centropages chierchiae and Temora stylifera) and a community of cold subsuperficial water distinguished by high specific diversity and a low number of individuals, one of its most characteristic elements being the eggs and larval stages of the Conostomasidae Maurolicus muelleri. The second component appears to be associated with an ecotone between the communities previously cited, and with a specific grouping (Rhincalanus nasutus, Eucalanus monachiis, Pseudocalanus elongatus, Temora longicornis, etc.) resulting from the peripheral displacement of subsuperficial elements brought to the surface by the cyclonic circulation of water masses between the Atlantic current and the Spanish coast.

Feeding of marine planktonic copepods on mixed phytoplankton

The feeding of juveniles and adults of the copepods Eucalanus pileatus, Temora stylifera and T. turbinata fed a mixture of the phytoplankton Skeletonema costatum, Leptocylindrus danicus and Rhizosolenia alata f. indica was studied at 20°C. E. pileatus nauplii, copepodids and adult females ingest similar percentages of the 3 algae in terms of carbon. Temora juveniles younger than CII ingest mainly S. costatum; at more advanced developmental stages, the ingestion rate on S. costatum remains constant whereas feeding on L. danicus and R. alata f. indica increases with increasing body weight. Feeding on high concentrations of large particles reduces the grazing pressure on small particles, thus favoring zooplankton which require small-sized food.

Analyse pondérale, élémentaire et calorimétrique des stades juvéniles de Copépodes pélagiques au cours d'une année

The change in dry weight over a year for the five copepodid states of Centropages typicus and Temora stylifera is given. The amounts of carbon and nitrogen, expressed as percentages of dry weight, are higher for copepodids than for adults. The values of the C N ratios may be regarded as constant for the different stages and of the same order as those of the adults. The calorific values of young stages are higher than those of adults, because of the relatively high carbon content. A good correlation was found between the caloric value per animal (or per unit dry weight) and the dry weight of individuals. It seems that the ecological efficiency in terms of energy transport will be greater when the copepod populations are younger.

Étude de la respiration et de l'excrétion de quelques copépodes planctoniques (crustacea) dans la zone de remontée d'eau profonde des côtes marocaines

Anatomical, biochemical, and metabolic characteristics of Atlantic copepods have been assessed during the summer upwelling off the coast of Morocco. The respiratory rate increases between 13° and 20 °C, with a Q 10 varying from 1.8 to 5.3. At temperatures higher than 20 °C there seems to be regulation in Acartia clausi Giesbrecht and Centropages typicus Kröyer, both abundant in warm waters, but not for other species whose respiration rate decreases. Respiration may be expressed as a function of temperature and dry weight as: R = 1.755 · 1.097 T · W 1.019, with a mean Q 10 of 2.47 for planktonic copepods during our cruise. The copepods excrete about 14.13 % of nitrogen per day, the Q 10 of the excretion rates being low. Temora stylifera (Dana) has been further investigated with regard to the effect of starvation on metabolism. Respiration, excretion and specific excretion immediately decrease; the oxygen nitrogen ratio decreases after 4 days, and after one week starvation the copepod survives on proteins exclusively. Calanus helgolandicus (Claus) has been studied in view of the energetic aspects of its vertical migration. It is shown that, depending on the ingestion rate, phytoplankton biomass, and temperature the vertical migration will either be energetically rewarding, with an optimal time in the upper layer for the largest profit, or unfavourable; in the latter case it might be suitable for the organism to adapt its metabolism to conditions at depth in order to survive.

Feeding four species of pelagic copepods under experimental conditions

Different qualitative and quantitative aspects of feeding with varied compositions of diets have been studied in 4 species of pelagic copepods: Calanus helgolandicus, Centropages typicus, Temora stylifera and Acartia clausi. By feeding copepods different algal concentrations, it was shown that when food concentration increases grazing rate decreases; the ingestion rate remains fairly constant in the lower range of concentrations, but then increases, reaching a plateau at higher algal concentrations. There is a significant correlation between daily food intake and fecal pellet production. On a pluri-algal diet, selective grazing is observed: larger phytoplankton cells are more efficiently removed than smaller ones. Using Artemia nauplii, it is shown that the copepods studied are also able to eatch and ingest animal prey. Increased daily food intake affects respiration and oviposition. Metabolic requirements, gross growth-efficiency, and food assimilation have been ealculated in Calanus helgolandicus, Centropages typicus and T. stylifera for a large range of algal concentrations.

Sex ratio in the pelagic copepods Temora stylifera Dana and Centropages typicus Krøyer

From the study of several plankton samples from the surface of southern Aegean Sea it is found that the sex ratio in Temora stylifera Dana and Centropages typicus Krøyer varies considerably (from 40 % to 132 % for Temora and from 24 % to 178 % for Centropages). The mean sex ratio shows a seasonal fluctuations. For these species the highest sex ratio is observed during the period of greatest abundance, that is when the environmental factors are optimal for the species, and the minimum sex ratio during the period of minimum abundance. During the latter period there are adverse environmental factors and a scarcity of food; a large number of females and hence high fecundity will favour the survival of the species.

Influence des conditions expérimentales sur le taux respiratoire des copépodes planctoniques

Measurements of oxygen consumption were carried out on two planktonic copepods, Temora stylifera Dana and Centropages typicus Kröyer under two experimental conditions, namely, degree of confinement and length of time spent in the laboratory. The effect of population density was studied for concentrations between 0.1 animal/ml to 2 animals/ml; the highest rate of respiration was observed in both species for a concentration of 0.5 animal/ml. Concentrations higher (1 or 2 animals/ml) and lower one (0.2 to 0.4 animal/ml) caused a decrease in the respiratory rate. Single animals have respiratory rates similar to those found with a concentration of 0.5 animal/ml. The observed effect of population densities did not depend on the absolute experimental volumes. When animals were kept in the laboratory for periods up to 5 days, the rate of oxygen consumption remained fairly constant during 2 days, then reached a minimal level at the third day or slightly later. It appears from these results that particular attention must be paid to the effect of experimental conditions in the determination of absolute values of metabolism of copepods.

Plankton studies in a mangrove environment: V. salinity tolerances of some planktonic crustaceans

The salinity tolerances of adult females of some relevant species of planktonic copepods were studies in a mangrove region of the estuarine type, at 25º south latitude. Results showed a wide range in the salinity tolerances for the adultfemales of all the species studied. Based on these experiments the following order of salinity tolerance can be proposed: Pseudodiaptomus acutus > Euterpina acutifrons > Acartia lilljeborgi > Oithona ovalis > Centropages furcatus > Temora stylifera. A mechanism for the maintenance of Pseudodiaptomus acutus at certain regions of the area studied is proposed, based on experimental and field results. It seems probable, thus that salinity is an important factor in the distribution of some members of the zooplankton in this region.

Seasonal Occurrence of the Pelagic Copepoda in Mississippi Sound

Collections of planktonic copepods from Mississippi Sound were made from January 1965 to March 1966. The following fifteen free­ living copepods were identified: Eucalanus pileatus, Paracalanus par­vus, Centropages hamatus, Centropages furcatus, Temora stylifera, Temora longicornis, Labidocera aestiva, Labidocera species, Acartia tonsa, Oithona brevicornis, Oithona species, Oncaea venusta, Cory­caeus species, Sappharina nigromaculata and Euterpina acutifrons. It was found that there is a definite seasonal distribution of cope­pods in Mississippi Sound with peak populations of copepods occu­rring in the spring, summer and fall.

Peculiarities of hydrological and hydrochemical conditions in the south Baltic during the IGY. (In Russian; English Abstract) : Antonov A. E. and O. S. Roudneva, 1965. Okeanolog. Issled. Rezult. Issled. Programme. Mezhd. Geofiz. Goda. Mezhd, Geofiz. Komitet Presidiume. Akad. Nauk. SSSR. No. 13: 90–95.

Diatoms are major components of the marine microalgae and are generally considered to be the principal food source for small pelagic crustaceans such as copepods. Recently, some species of this algal class have been shown to produce abortifacient compounds (aldehydes) that block copepod embryogenesis, thereby acting as a form of birth control for predatory copepods. To test if diatoms also have deleterious effects on postembryonic development, several diatom species were used to rear larval stages of the calanoid copepod Temora stylifera to adulthood. Our results show that T. stylifera was only able to complete development from hatching to adulthood when reared with the flagellates Isochrysis galbana and the dinoflagellates Prorocentrum minimum and Oxyrrhis marina. The daily development and mortality rates observed were in the range of those reported from previous studies on T. stylifera (0.68–0.82 stage/day and 9.9–12.4%/day, respectively). In contrast, larvae reared on the diatoms Thalassiosira rotula, Skeletonema costatum and Phaeodactylum tricornutum were unable to complete development to adulthood and died without passing the naupliar phase or during the early copepodite stages. Daily mortality rates were higher than for nondiatom species (20.3–35.5%/day). Inhibitory effects on growth were not correlated to cell size of the algae. Final survivorship of larvae fed P. minimum and I. galbana significantly improved (70–80%) when larvae were generated from females preconditioned with P. minimum for 24 h. The same treatment had no beneficial effect on larvae fed with T. rotula or S. costatum, which died again before the adult stage. Although larvae completed development in one replicate with T. rotula and final survivorship improved to 34% (compared to 7% in nauplii from nonconditioned females), this value was, in any case, lower than with nondiatom diets. No morphological aberrations were found in larvae fed on diatoms, even though they were unable to complete their life cycle and died for unknown reasons. By contrast, nauplii produced by females fed the diatom T. rotula for 7 days showed strong congenital defects such as asymmetrical bodies and reduced number of feeding appendages. Our results suggest that diatoms, which have already been shown to have deleterious effects on copepod embryonic development, may also have insidious effects on larval growth of this copepod species.

Causes of mass mortalities of scallops ( Placopecten magellanicus) in the Southwestern Gulf of St. Lawrence : Dickie, L. M. and J. C. Medcof, 1963 J. Fish. Res. Bd., Canad, (20) 2: 451–482

We explored the small-scale behavior of the calanoid copepod Temora stylifera in relation to the diatoms Chaetoceros socialis, Leptocylindrus aporus, Leptocylindrus danicus and Pseudo-nitzschia calliantha offered as monospecific diets at similar carbon concentrations. These four diatoms are characterized by distinct size, shape and colony forming ability and are important components of the autumnal bloom co-occurring with the seasonal peak of T. stylifera abundance in Mediterranean coastal waters. High-speed video recordings showed that T. stylifera acquired cells in a suspension feeding mode while creating feeding currents. Copepod behavior was quantified in terms of feeding, motion, and grooming activities. T. stylifera spent more time in hovering than cruising in presence of all diets. The solitary L. aporus and P. calliantha elicited longer feeding bouts, lower appendage beat frequency and shorter grooming events compared to the colonial L. danicus and C. socialis. Overall the present results indicate that the behavioral responses of T. stylifera to different diatom diets were species-specific. The observed behavioral plasticity may help T. stylifera to adjust rapidly to changes in the food environment and this can be advantageous in exploiting short-lived phytoplankton blooms.