Ecological aspects of bivalve adaptation to salinity fluctuations on the example of Anadara Kagoshimensis

Impact of salinity stress on the ark clam (Anadara kagoshimensis (Tokunaga, 1906)) hemocyte functions were investigated using flow cytometry and light scattering technique. In control group water salinity was 18 ppm and experimental groups were carried at 14 ppm, 8 ppm, 35 ppm and 45 ppm. Hemolymph osmolarity decreased at hypoosmotic conditions and increased after hyperosmotic treatment. Osmotic stress induced changes in osmotic fragility of the ark clam hemocytes. Salinity 14 ppm did not affect the functional parameters of hemocytes. Incubation of ark clams at salinity and 35 ppm did not influence on the mitochondrial membrane potential of hemocytes but led to a decrease in hemocyte reactive oxygen species (ROS) production by 30 % compared to control. An increase in water salinity to 45 ppm and its decrease to 8 ppm induced substantial changes in the ROS production and mitochondrial membrane potential of hemocytes. Hyposalinity (8 ppm) led to an increase in ROS production by hemocytes (up to 2.4 times) and mitochondrial membrane potential (up to 1.3 times). An increase of salinity level from 18 ppm to 45 ppm decreased the total ability of hemocytes to produce ROS by 11% and increased mitochondrial potential of hemocytes by 150%.

Изучение процессов тканевого роста у черноморских видов двустворчатых моллюсков в прибрежных биоценозах Севастополя и южнобережного Крыма (1987–2018 гг.)

Представлен обзор собственных и литературных данных по морфофизиологическим и биохимическим показателям процессов тканевого роста у двустворчатых моллюсков Чёрного моря: черноморской мидии Mytilus galloprovincialis (Lam.), устрицы Crassostrea gigas (Thunberg, 1783), анадары Anadara kagoshimensis (Tokunaga, 1906) и гребешка Flexopecten glaber ponticus (Bucquoy, Dautzenberg & Dollfus, 1889), обитающих в прибрежных биоценозах Севастополя и южнобережного Крыма. Критериями оценки являлись такие основные показатели, как сырая и сухая масса, содержание суммарных рибонуклеиновых кислот (РНК), ДНК, содержание белка, а также ростовые индексы РНК / ДНК и РНК / сырая масса.

POLYDORA WEBSTERI - A COMMENSAL OF ANADARA KAGOSHIMENSIS IN THE AZOV-BLACK SEA REGION

In January 2020, the presence of polychaete borers in the invader clam Anadara kagoshimensis (Tokunaga, 1906) was noted at the Chushka spit near Port Kavkas. Morphological analysis showed that the polychaetes belong to the species Polydora websteri Hartman in Loosanoff & Engle, 1943, non-indigenous to the Azov-Black Sea basin. This species was first recorded in coastal waters of Romania on carbonate rocks in 1997, followed by findings in 2009 and 2019 in coastal areas of Sevastopol and Lake Donuzlav, correspondingly, in oysters Crassostrea gigas (Thunberg, 1793). Polydora websteri has not previously been recorded from the Kerch Strait and the Sea of Azov. Its presence in Anadara kagoshimensis in the Azov-Black Sea region, which is an invasion area for both species, is shown for the first time.

Таксономическая структура меропланктона прибрежных вод Карадага (май, сентябрь 2018 г.)

В рамках комплексных экологических исследований, выполненных в мае и сентябре 2018 г. в прибрежной акватории Карадага, получены данные по таксономической структуре меропланктона. Пробы меропланктона отбирали сетью Джеди (диаметр входного отверстия 36 см, размер ячеи мельничного газа – 135 мкм), обработку проводили на живом материале путем тотального подсчета личинок в камере Богорова под бинокуляром МБС–9. Показано, что максимальная численность личинок донных беспозвоночных (3920 экз./м3) зарегистрирована в мае в Коктебельской бухте, минимальная (551 экз./м3) – в районе Биостанции. В сентябре максимум (2160 экз./м3) отмечен в Сердоликовой бухте, минимум (659 экз./м3) – как и в мае, в районе Биостанции. Отмечено, что в Коктебельской бухте в мае более 60% суммарной численности меропланктона составляли науплиусы усоногого рака Amphibalanus improvisus (Darwin, 1854), личинки двустворчатых моллюсков не превышали 18%. В акватории заповедника на долю личинок Bivalvia приходилось более 70%, а личинок Cirripedia – до 11% суммарной численности меропланктона. В сентябре таксономическая структура меропланктона была практически одинакова на всей исследуемой акватории. Проанализировано изменение численности личинок мидии Mytilus galloprovincialis Lamarck, 1819. Их максимальная численность (1248 экз./м3) отмечена в мае у мыса Мальчин, минимальная – как в мае, так и в сентябре, у Биостанции. Наличие в планктоне личинок двустворчатых моллюсков Mya arenaria Linnaeus, 1758 и Anadara kagoshimensis (Tokunaga, 1906) подтверждает влияние азовоморских вод на прибрежную фауну Карадага.

Morphometric parameters of erythroid hemocytes of alien mollusc Anadara kagoshimensis (Bivalvia, Arcidae) under normoxia and anoxia

In the present work we investigated the influence of three days anoxia on hematological parameters, morphological and functional characteristics of eryhroid cells of alien bivalve Anadara kagoshimensis . Oxygen concentration in seawater was decreased by bubbling with nitrogen gas for 5 h. Temperature was maintained at 20±1oC and photoperiod was 12h day: 12h night. Extrapallial fluids were sampled by a puncture of extrapalial cavity. Three-day exposure to anoxia caused pronounced cellular responses. At the organismic level changes were not observed, as hemoglobin concentration the total number of erythroid cells and mean hemoglobin concentration ( МСН ) remained at the level of normoxia. We observed an increase of cellular anomalies, i.e. shistocytes and erythroid cells with polymorphic nuclei, and cells undergoing reactive amitotic division, which resulted in formation of binuclear cells. Nuclear volume ( V ) increased for more than 40 % compared to control level. This increase depended on the duration of anoxia. Changes in cellular volume ( V ) possessed a complicated manner. At the end of experimental period (3rd day of anoxia) nucleo- cytoplasmic ratio was 36% lower comparing to normoxia. Exposure to anoxia did not cause mortality of erythroid cells. The number or red blood cell shades observed on slides remained at control level.

THE EXPANSION OF THE BIVALVE ANADARA KAGOSHIMENSIS (TOKUNAGA, 1906) IN THE SEA OF AZOV

The dispersion of the Asian bivalve Anadara kagoshimensis in the Sea of Azov continues for more than 30 years. The study of the expansion of A. kagoshimensis is based on the materials of annual bottom grab surveys performed in the Sea of Azov in 1989-2018. The process of dispersion of the mollusk is considered through the changes of the range area, the indicators of abundance (specific abundance, biomass, total stock) and the structure of the population. The main stages of the invasion process are highlighted and discussed. The influence of various environmental factors on the distribution and quantitative indicators of the development of the mollusk population is estimated. It is shown that salinity is the key factor determining the expansion of the mollusk in the Sea of Azov.