Sex ratios of calanoid copepods in the northern Black Sea
In: Regional Studies in Marine Science. Elsevier: Amsterdam. ISSN 2352-4855, more
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| Keyword |
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| Author keywords |
Sex ratio, Calanoid copepods, Mandible, Seminal receptacle, Black Sea |
| Authors | | Top |
- Prusova, I.Y.
- Galagovets, E.A.
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| Abstract |
The adult and juvenile sex ratios in field populations of the most common species of calanoid copepods Acartia clausi Giesbrecht, 1889, Acartia tonsa Dana, 1849, Centropages ponticus Karavaev, 1895, Paracalanus parvus (Claus, 1863), and Pseudocalanus elongatus (Brady, 1865) were studied on the basis of zooplankton materials collected in the Black Sea in 2011–2017. In all analyzed species, the adult sex ratios were female-biased, but to a different extent, which reflects the peculiarities of their morphology and ecology. The highest degree of female-skewed adult sex-ratios was observed in P. parvus and P. elongatus, species in which females have seminal receptacles, and males have atrophied mouth appendages. The closest to equity sex ratio was registered in C. ponticus, a species in which females lack seminal receptacles, and males have well-developed mouthparts. Thermophilic, present in plankton only during the warm season, A. tonsa and C. ponticus demonstrated the highest average values of the proportion of males. Seasonal changes in adult sex ratios were registered only in P. elongatus. Juveniles of the fifth stage in A. clausi, A. tonsa, C. ponticus, and P. elongatus had average sex ratios close to 1:1 with a slight bias towards the prevalence of females. In copepodites of P. parvus, this bias was expressed to a much greater extent, which is possibly due to the counting method, when immature hermaphrodites were referred to as females. The microscope images of the mandibles of the analyzed species are given. |
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