This study, accomplished is focused on the spatial and temporal distribution and species composition of phytoplankton in the southwestern Caspian Sea between January 2008 and December 2008. Samples were collected from 11 stations along three transects known as Lisar, Anzali and Sefidrood. This study identified 43 phytoplankton species comprised of diatoms (25 species), dinoflagellates (7 species), chlorophytes (6 species), cyanophytes (4 species), and euglenoids (1 species) were identified. The study showed, diatom Dactyliosolen fragilissimus and the dinofllagelate Prorocentrum cordatum numerically dominate the southwestern Caspian Sea. The annual average phytoplankton density was calculated as 2.35E+04 ± 1.63E+04 Cell L -1 , with the maximum value recorded in the winter (4.50E+04 ± 3.90E+04 Cell L -1 ). Diatoms were dominant during the autumn and winter (77.0% and 96.0%, respectively), while dinoflagellates were prevalent during the spring and summer (89.0% and 86.0%, respectively). The annual average chlorophyll a was calculated as 9.26±3.54 μg L -1 , with the maximum values were recorded in the winter (16.9±5.60 μg L -1 ). This is supported by the Spearman rank correlation result between phytoplankton abundance and chlorophyll a (r=0.551). The high phytoplankton cell density and chlorophyll a concentration coincided with the poor species composition. Güney Batı Hazar Denizi'nde Fitoplanktonun Tür Kompozisyonu ve Bolluğu ÖzetOcak 2008 ve Aralık 2008 arasında yapılan bu çalışma Güney Batı Hazar Denizi'nde fitoplankton'un uzaysal ve zamansal dağılımları ve tür kompozisyoları üzerine odaklanmıştır. Örnekler Lisar, Anzali and Sefidrood olarak bilinen üç kesit boyunca uzanan 11 istasyon noktasından toplandı. Diatom (25 tür), dinoflagellat (7 tür), klorofit (6 tür), cyanofit (4 tür) ve euglenoidlerden (1 tür) oluşan toplam 43 fitoplankton türü tayin edildi. Çalışma, diatom Dactyliosolen fragilissimus ve dinofllagellat Prorocentrum cordatum türlerinin sayısal olarak Güney Batı Hazar Denizini kontrol ettiğini gösterdi. Yıllık ortalama fitoplankton yoğunluğu kış döneminde kaydedilen maksimum değeriyle (4,50E+04 ± 3,90E+04 Cell L -1 ) 2,35E+04 ± 1,63E+04 Cell L -1 olarak hesaplandı. Dinoflagellatlar ilkbahar ve yaz döneminde (sırasıyla %89,0 ve 86,0), diatomeler sonbahar ve kış dönemi boyunca baskın grup olmuşlardır (sırasıyla 77,0% ve 96,0). Kışın kaydedilen maksimum değeriyle (16,9 ± 5,60 μg L -1 ), yıllık ortalama klorofil a değeri 9,26 ± 3,54 μg L -1 olarak hesaplandı. Bu durum fitoplankton bolluğu ve klorofil a arasındaki Spearman rank korelasyon sonucu (r=0,551) tarafından da desteklenmiştir. Fitoplankton biyomas ve klorofil a yüksek olduğu halde, tür çeşitliliği bakımından fakir olmuştur.

Riparian countries of the Caspian Sea have been evaluating the pros and cons of the predatory ctenophore Beroe ovata as a control agent against the invasive ctenophore Mnemiopsis leidyi, which has enormous adverse impacts on the fishery resources as well as on the biodiversity in this once fertile sea. To assess the viability of B. ovata establishment in the Caspian Sea, the survival and some physiological characteristics (feeding, respiration, reproduction and growth) of the predatory ctenophore were studied in Caspian Sea water (12.6 ppt salinity) conditions using animals transported from the Black and Marmara Seas to a laboratory on the Iranian Caspian coast. The findings of the study showed that when salinity was gradually decreased from 22 to 12.6 ppt, B. ovata were able to adapt well to Caspian Sea water. Most of the predatory ctenophores began to swim actively and to feed on M. leidyi within 15 to 30 min following each step of acclimation. The feeding rate of B. ovata ranged from 14 to 765% of body wet weight and was highest for smaller individuals (i.e. 13 to 16 mm). Over the measured weight range of 0.23 to 3.87 g wet wt, the weight-specific respiration rate was independent of weight. The daily specific growth rate of adult ctenophores was 7 to 11% of body wet wt. B. ovata specimens were spawned and their eggs were hatched in Caspian Sea water, but the larvae survived for only a few hours. The energy budget of B. ovata calculated from food consumption, respiration and growth rates revealed a mean assimilation efficiency of 0.72 ± 0.1, a gross growth efficiency (K 1 ) of 0.48 ± 0.12 and a net efficiency (K 2 ) of 0.66 ± 0.06. Based on these physiological data, we suggest that in the Caspian Sea, B. ovata will be able to ingest M. leidyi intensively. However, concerning the reduction of the M. leidyi population and consequently the reversal of its adverse impact on this ecosystem, the failure of larval growth observed under experimental conditions (most probably due to poor handling) remains the main obstacle to overcome in the successful establishment of B. ovata in the Caspian Sea.

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Seasonal changes are the most important factor in temporal variability of macroinvertebrates communities in marine benthic zone. Realizing the pattern of these changes are the key attributes to maintain benthic resources. For this purpose this study aimed to investigate temporal variability of macroinvertebrates diversity patterns in different seasons in Hormozgan province waters, Persian Gulf. Five sites were identified and sampling was carried out randomly at three places with three replicate in each site from autumn 2014 to spring 2015. Physiochemical properties of water were recorded in each sampling site. Total of 19 macroinvertebrate orders were identified form four seasons in all sites. Results showed that Polychaeta were dominant taxa in all seasons and maximum diversity of benthic macroinvertebrates exhibitedin winter. According to evenness index (E1), abundances of species were most balanced in spring. Analysis of weight and density revealed that the species diversity and mean weight of macroinvertebrates had maximum in winter and minimum in summer. Macroinvertebrate community structure was similar in the spring and summer and partly discriminated from remaining two seasons. SIMPER analysis confirmed these dissimilarities and revealed that Foraminifera, Gastropoda and Polychaeta have three major contributions in dissimilarities between seasons. According to BIO-ENV analysis, oxygen and chlorophyll a were the best variables (r = 0.7143) explaining changes in the abundance over time of the benthic fauna under study. On the contrary, eight

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