Effect of temperature on clearance rate, daily ration and digestion time of Mnemiopsis leidyi from the southern Caspian Sea

The effect of temperature on the main feeding parameters of Mnemiopsis leidyi from the southern Caspian Sea was studied in 2002. The clearance rates and daily rations were estimated from laboratory experiments in a wide range of temperatures from 12 to 27 ºC for M. leidyi of 12–17 mm in length. Clearance rate values changed from 52.5 to 107.3 ml ind-1 h-1. The coefficient Q10 in temperature 12 - 20 ºC was higher than that in 20 - 27 ºC (3.81 and 1.91, respectively). The specific daily ration changed from 1.56±0.19 to 0.24±0.05 mg C mg C-1 day-1 when temperature decreased from 27 ºC to 12 ºC. The direct relationship occurred between daily ration and temperature (R2=0.99). The digestion time decreased with temperature rise and did not display any clear relation to quantity of digested food.

Zooplankton of the Black Sea and the Eastern Mediterranean: Similarities and dissimilarities

A synthesis of data on abundance and biomass of zooplankton in the Eastern Mediterranean (EMED) and the Black Sea shows major differences in the composition and structure of pelagic communities in the two basins. Few Mediterranean planktonic animals have invaded and acclimatised in the Black Sea. The great bulk of Black Sea species is represented by coastal inhabitants that spread throughout the whole basin. This process has been called “neritization” of the Black Sea fauna. Peculiarities in zooplankton assemblages of the Black Sea have been further strengthened over the last few decades due to increasing eutrophication and the massive invasion of the ctenophore Mnemiopsis leidyi. The relative contribution of copepods, cladocerans, chaetognaths, and appendicularians to total zooplankton biomass has notably decreased , whereas gelatinous groups (mainly represented by Mnemiopsis and Aurelia aurita) contributed up to 99% of total wet weight in 1995 in the Black Sea.The basic features of planktonic fauna in the Black Sea are mainly due do the geo-morphological characters of the basin and the limited exchanges with the EMED, that are confined to the surface-subsurface layers in the Dardanelles and Bosphorus Straits. However, the dramatic changes that recently occurred in the structure of zooplankton assemblages seem to have been caused by heavy anthropogenic impact on the pelagic system

Reproduction of the ctenophore, Beroe ovata, in the Caspian Sea water

The experiments with Beroe ovata showed that this ctenophore can survive and reproduce in the Caspian Sea water, though at far lower rate than in the Black Sea; larval growth in the Caspian Sea water was also slower and mortality higher. Maximum fecundity of 2210 and 240 eggs recorded in laboratories of Turkey and Iran, respectively. About 34 to 100% of eggs in the Caspian Sea water could not develop and hatch. Larvae were at different stages of development, usually with size between 1.2 to 2mm. The highest number of eggs and larvae were obtained in tanks where Beroe individuals were together with Mnemiopsis leidyi. The poor reproduction of B. ovata in the Caspian Sea water could be due to both the acclimation stress to low salinity and possible damage of individuals during the transportation

The ecology of the common whelk, Buccinum undatum L. off Douglas, Isle of Man, with particular reference to its ecological energetics

Available from British Library Document Supply Centre- DSC:DX174016 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Seasonal changes in the composition and abundance of zooplankton in the seas of the Mediterranean basin [Akdeniz Baseni'nin Zooplankton Bolluk ve Kompozisyonundaki Mevsimsel Degişimler]

Seasonal changes in the composition, abundance and biomass of zooplankton in the seas of the Mediterranean basin (the Mediterranean, Black and Azov seas) have been reviewed using our own data and data from the literature. In the deep-water central regions of the seas, the seasonal cycle of zooplankton abundance is characterised by one maximum occuring in spring or summer. in the coastal regions, two to three peaks (spring, summer and autumn) exist for the zooplankton abundance. The amplitude of seasonal fluctuations in abundance for the coastal zone as a rule is much wider than for the deep-water regions. In both coastal and central deep-water regions, the amplitude of seasonal fluctuations increases from the Mediterranean to the Black and Azov seas, as well as from south to north in each sea. This corresponds to seasonal changes in the amplitude of water temperature and the abundance of phytoplankton as the basic factors influencing zooplankton abundance. The dominant role in defining seasonal changes in total zooplankton abundance is played by the main group - copepods, which in some years form up to 90% of zooplankton numbers and biomass. During the warm period of a year, cladocerans may replace copepods

Salinity tolerance of Calanus euxinus in theBlack and Marmara Seas

We investigated how stenohalinic Black Sea Calanus euxinus, when migrating to the north-eastern Marmara Sea, can adapt to the pronounced salinity gradient there. During field observations (2005 to 2008) females of Calanus euxinus with significantly smaller body length (compared with those inhabiting the brackish Black Sea at 17 to 18 psu) were found in the deep, high-saline (~38.5 psu) layers of the Marmara Sea. Similar diameters of eggs laid by small- and large-sized females and similar respiration rates in nauplii hatched from these eggs indicated the Black Sea origin of the C. euxinus population found in the Marmara Sea. To understand the morphological and physiological changes in C. euxinus during acclimation to high salinity, we studied the effect of salinity on behaviour, food consumption, growth patterns, hatching success and respiration rate of C. euxinus individuals collected in the Black and Marmara Seas. It was shown that the range of salinity tolerance for adult C. euxinus (17 to 30 psu) from the Black Sea was extended gradually to 40 psu after 1 d of acclimation to the high salinity of the Marmara Sea. Long-term parental salinity acclimation facilitates survival of eggs descending through the salinity gradient of the Marmara Sea, from brackish upper layers to deep, high-saline strata, or eggs laid in deep layers. While weight-specific respiration rates at the same temperature did not differ for C. euxinus juveniles from the Black and Marmara Seas, they were ~2 times higher in preadults and adults from the Marmara Sea than from the Black Sea. This may be the reason for the decrease in length and weight increments of these stages probably leadin