Development of Calanus euxinus during spring cold homothermy in the Black Sea

Abstract

In copepodites and adults of Calanus euxinus abundance, body length and weight, chemical composition and respiration rate in relation to age were studied during the cruise of R/V 'Knorr' in April 2003 in the southwestern Black Sea and in laboratory experiments. Data on morphology and physiology of C. euxinus collected during other seasons were also used in comparative analyses. At high concentrations of the diatom Proboscia alata during spring homothermy (6.8 to 8.5°C) C. euxinus did not undertake diel vertical migrations to the oxygen minimum zone (OMZ). The majority of the population was located above the OMZ, feeding on phytoplankton during nighttime and daytime whilst nearly 10% of copepodite stages IV and V (CIV and CV) and adults remained constantly in the OMZ. Although a diapausing stock of the population began to form in the OMZ, the majority of CV developed without diapause. The development times of copepodite stages at 8°C were determined on the basis of field observations of ontogenetic changes in carbon content and calculated absolute growth rates. Development time from CI to CV amounted to 22 d. In CV the time for lipid deposition from 0.008 ± 0.007 mm 3 in postmolts up to a maximum volume of 0.165 ± 0.054 mm 3 in intermolts constituted 26 d. The total generation time from eggs to adults is not less than about 66 d. KEY WORDS: Calanus euxinus · Lipid storage · Respiration · Growth · Black Sea · Spring cold · HomothermyResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 374: 199-213, 2009 other hypothesis, Calanus, like other 'boreal relicts', entered the Black Sea when it was connected with the North Sea across Europe during the period of retreating glaciers (Zaitsev 2006). This is in agreement with the results of Papadopoulos et al. (2005) suggesting that the divergences between the northeastern Atlantic, Mediterranean and Black Sea C. helgolandicus populations are much older than the estimated dates of colonization of the Mediterranean and Black Seas. However, according to Polischuk (1984) the last connection between the North and Black Seas could have been in the Late Holocene (2800 to 2700 BP).Calanus euxinus is a dominant component of the zooplankton biomass in the Rim Current system of the Black Sea. The ecology of this species differs significantly from that of C. helgolandicus in other European seas due to the characteristics of the basin.Calanus helgolandicus typically inhabits saline waters (32 to 39 ‰) with temperatures of 9 to 20°C. This wide range is mainly due to seasonal variation; the temperature does not range widely between populations. Seasonal changes in abundance of C. helgolandicus are positively correlated with temperature (Bonnet et al. 2005) and food availability (Rey-Rassat et al. 2004). Overwintering C. helgolandicus descend to deep water and are separated spatially from the part of the population that develops in surface layers.In contrast, Calanus euxinus has adapted to the low salinity of the Black Sea waters (18...

Influence of food quality on lipids and essential fatty acids in the body of the Black Sea sprat Sprattus sprattus phalericus (Clupeidae)

“…During artificial fish breeding, it was shown that insufficient intake of EPA and DHA with food, as well as changes in their ratio in the diet, worsen the state of larvae and juvenile fish (Yuneva Table 3. Size, weight, and biochemical parameters of Calanus euxinus and Acartia clausi collected on the deep-water shelf near Sevastopol (by Yuneva and Shchepkina, 2005;Svetlichny et al, 2009). …”

Salinity tolerance of Calanus euxinus in the Black and Marmara Seas

“…The body wet weight of Calanus euxinus copepodites and females was also calculated using the data of body volume and taking into account the mean body density determined as ρ = 1.06 -0.0016SV s , where SV s (%) is the share of the oil sac in the body volume determined as reported by Svetlichny et al (1998Svetlichny et al ( , 2009). Length and width of the prosome were measured to the nearest 10 µm under a dissecting microscope fitted with an eyepiece micrometer.…”

“…The oxygen concentration and respiration rate were measured according to the method described in Svetlichny & Hubareva (2005) and Svetlichny et al (2009).…”

Modelling optimal behavioural strategies in structured populations using a novel theoretical framework

“…One can see that the deepest depth of DVM increases in summer and decreases in winter. In the literature, seasonal variation of migration depths is often connected to seasonal change of the width of (i) the oxygen zone in the north-eastern Black Sea and (ii) the zone with suitable water temperature ranges for the species considered 32 . However, the role of the oxygen zone and temperature conditions in DVM are not yet well understood and this model study is intended to shed some light on this long-standing question 31–33 .…”