Study on distribution of the Ctenophore Mnemiopsis leidyi in the Caspian Sea (Iranian Coasts)

In the early 1980s, an alien ctenophore Mnemiopsis leidyi already known as a gelatinous zooplankton was transported (likely via ballast waters) to the Caspian Sea from its introduced or native water of the Black Sea or western Atlantic which caused negative impacts. In this report, distribution of M. leidyi, planktonic and benthic organisms had been investigated in the Southern Caspian Sea (Iranian waters) in 6 transects consisted of Lisar, Anzali, Sefidroud, Nowshar, Babolsar and Amirabad at 26 stations during 2005 and 2006. As a whole, 1422 samples had been analyzed included 258, 346, 217, 117 and 484 belong to ctenophore, phytoplankton, zooplankton, benthos and physicochemical parameters, respectively. M. leidyi abundance and biomass were fluctuated between 284-2751 ind.m^-2 and 16.9- 390/9 g.m^-2 respectively in 2005 while maximum abundance and biomass were recorded in autumn and minimum in winter. In 2006, its mean abundance and biomass were 184-2150 ind.m^-2 and 9.1- 209/8 g.m^-2 respectively. M. leidyi maximum abundance and biomass were noted in summer and its minimum in spring and winter months. Overall, mean M. leidyi abundance and biomass were recorded in 20 m within 1202 ind.m^-2 and 139.5 g.m^-2 respectively. Maximum size of the ctenophore was recorded as 55 and 60 mm in 2005 to 2006 respectively, while less than 10 mm length frequency consisted 83.16 and 82.88 per cent of total population. Spatial_ temporal distribution of M. leidyi in different regions showed it was more abundant in west and east (714- 4494 ind.m^-2) ratio to central parts (13-1519 ind.m^-2) of the Southern Caspian Sea. Species composition of zooplankton had shown the negatively impacts of M. leidyi invasion in the period of sampling as the only 17 holozooplankton were determined with Rotatoria (7 species), Copepoda (4 species), Ciliophora (4 species) and cladocera (1 species). Zooplankton maximum abundance and biomass were recorded in February (3039742901 ind.m^-3 and 372.1575.4 mg.m^-3) respectively and its minimum were in July (12211601 ind.m^-3 and 6.9 7.7 mg.m^-3) respectively which was belonged to Rotatoria (76%) and Copepoda (10%). In this study, 21 species of benthic fauna were deter minted belong to Pseudocumidae (5 species), Gamaridae (4 species) Amphartidae (3 species), Oligochaeta, Balanidae, Xantidae, Nereidae, Scarbicularidae, Carididae, Mytilidae, Herpobdellidae and Chironomidae (each 1 species). Oligocheata was recorded with maximum abundance (943 2502 ind.m-2) and Bivalve consisted of higher biomass (68.7162.5 g.m^-2). From five phyla of phytoplankton, 172 species were determined of Chrysophyta (74 species), Cyanophyta (32 species), Chlorophyta (32 species), Pyrrophyta (24 species) and Euglenophyta (13 species), in which Chrysophyta and Pyrrophyta were noted as main groups with their maximum abundance (up to 65%) and biomass (93%). Maximum water temperature was recorded in August with 29.52.5 ֯C and minimum in February by 9.31.3 ֯C. Mean value of salinity was 12.010.90 ppt, secchi disk ranged between 0.2 to 7 m and oxygen demand varied from 5.95 to 10.54 mg. l^-1). Moreover, silicate concentration was recorded between 200 to 300μg.L^-1, Phosphate measured from 31-47 μg.L^-1, Ammonia varied in 10-29 μg.L^-1, Nitrite (0.6- 1.7 μg.L^-1), Nitrate (0.06-4.20 μg.L^-1, which mainly accumulated in coastal waters of the southern Caspian Sea

Determination of chlorophyll-a fluctuations and its relations with abiotic factors and phytoplankton community with emphasis on bloom potential in the southeast Caspian Sea water (Mazandaran-Goharbaran) in order the feasibility of marine cage culture

Concentration of chlorophyll-a and quantitative feature of phytoplankton are major concern in primary production estimation and prediction of probably algal blooms in aquatic ecosystems. The subject has important role in development and sustainable exploitation of marine culture. The goals of the project are study of chlorophyll-a concentration changes and its relations to variations of phytoplankton community structure parameters and abiotic factors (environmental and nutrients matters) in the costal waters of the Caspian Sea- Goharbaran region during 2013-2014. Monthly water samples were collected from different layers (surface, 5 and 10m) and depths (5, 10 and 15 m). The minimum mean (±SE) of abundance and biomass reported in spring (39± 9 million cells/m^3) and summer (94± 40 mg/m^3) respectively. The results showed maximum abundance (553± 58 million cells/m^3) and biomass (1209± 106 mg/m^3) in winter season. The minimum and maximum mean (±SE) values of chlorophyll-a recorded in spring (0.60± 0.05) and autumn (4.56± 0.23) mg/m^3, respectively. The changes trend of field chlorophyll-a concentration was confirmed by satelit data. Bacillariophyta showed the highest percent abundance in all seasons except in summer which it was for chlorophyta phylum. Pyrrophyta was the second dominant phylum in winter as well as spring; however its contribution in phytoplankton abundance of winter was low. The first dominant abundance species in spring, summer, fall and winter were Prorocentrum cordatum, Binuclearia lauterbornii, Thalassionema nitzschioides and Pseudonitzschia seriata respectively. Based on the results the species of Prorocentrum (scutellum+ proximum+obtusum) in spring and fall seasons, Cyclotella menenghiniana in summer and Pseudonitzschia seriata in winter showed the highest role in phytoplankton biomass forming. chlorophyll-a concentration showed significant Pearson correlations with biomass of total phytoplankton, bacillariophyta, pyrrophyta and chlorophyta phyla, dominant species, size cells of dominant species, water temperature, clearancy, nutrients matters. The study showed that chlorophyll-a cells content of winter dominant species was lower than fall dominant species. The Change of seasonal taxonomic phytoplankton pattern showed important role in relationship between chlorophyll-a cells content with biotic and abiotic factors. Meanwhile the values of temperature, nutrient matters, pH, pattern of dominant phytoplankton species showed significant roles on decoupling between chlorophyll-a and biomass changes pattern. The critical time of algal bloom recorded from September to January and March based on chlorophyll-a concentration. Spatial critical algal bloom was more obvious on surface water from October to December based on chlorophyll-a concentration. Pseudonitzschia seriata and Binuclearia lauterbornii species classified in medium bloom threshold (in winter and summer respectively) in all sampling depths. However Thalassionema nitzschioides (in fall) was in medium bloom threshold in 10 and 15m depths. As conclusion, in order to estimate logic primary production and predict algal blooms in the cage and pen culture sites it is necessary that all phytoplankton parameters such as chlorophyll-a concentration, biomass, abundance, shape, size, biological and ecological chracterstics of dominant species are considered. Because changes in the chlorophyll-biomass relationship could lead to obviouse errors interpretation of results and as well as unexpected field observations

The study of abundance and dynamic zooplankton in the Southern of Caspian Sea

The Caspian Sea is the largest lake, both by its area and volume. Zooplankton are very important in the food web since many animals eat them. The Sampling was done in 4 transacts in Anzali, Tonekaboun, Noushahr and Amirabad at 3 different depths including 5, 10 and 20 m. Sampling was carried out in four seasons of spring, summer, autumn and winter in 2013. The annual changes of zooplankton was between 392±113 ind./ m^3 in autumn (Amirabad) to 8065±11735 ind./m^3 in winter (Amirabad). The lowest density of zooplankton in the spring was 2207 ind./ m^3 in Anzali. The density of zooplankton in Tonekabon and Amirabad was 2.0 and 2.8 fold more than other transects respectively. The results showed that the abundance of zooplankton in summer was between 1964±470 ind./m^3 (Amirabad) to 5706±6088 ind./m^3 (Tonekabon). The biomass was 30.02, 52.22, 22.98 and 18.31 in Anzali, Tonekabon, noshahr and Amirabad respectively. The abundance of zooplankton in the autumn reached the lowest value. The lowest value was 392 ±113 ind./m^3 and 3.71±0.19 mg/m^3 (Amirabad) and highest value was 2280 ±1435 ind./ m3 and 20.23±14.50 5mg/m^3 (Anzali). The highest density was observed in Amirabad (8065 ind./m^3) and Anzali (8061 ind./m^3) in winter. The aim of this study was diversity, distribution, density and biomass of zooplankton in the southern of Caspian Sea

Study on macrobenthic communities in the range of fish cage-culture area (before breeding) in the southern Caspian Sea (Mazandaran coast-Kelarabad)

The abundance and biomass of benthic macroinvertebrates were studied in the place of fish cage culture in southern coasts of Caspian sea (Mazandaran waters- kelarabad). The goal of this study was to consider of fish cage culture effects on the abundance and biomass of benthic macroinvertebrates. The sampling was carried out in 3 stations in depth of 20 meter of Kelarabad waters monthly. In this study 7 species were identified belonged to 5 genus of 4 family. Totally 23442 sample of benthic invertebrates were counted that the lowest and highest abundance were in station 1(23.4%) and station 2(46.8%) respectively. The results of stations study showed that the highest abundance and biomass were in stations 2 and 3 with the average of 646 ± 1230.4 n/m^2 and 0.526 ± 1.001 gr/m^2 respectively. This coulld be respectively dependant to not settling of cage (witness station) and appearance of Cerastoderma glaucum because of its large body in station 1. The difference of abundance and biomass between different stations was not significant (p ›0.05). The study on abundance and biomass in different seasons showed that the highest abundance in autumn with the avarage of 888.13 ± 1371.58 n/m^2 belonged to Strblospio gynobranchiata and the highest biomass belonged to C. glaucum which was because of appearance of not native species of polychaeta and also the species with shell covering from bivalvia. The results showed that the specie of S. gynobranchiata from polychaeta including 93.3% of abundance was the dominant specie that could be related to appropriate ecological conditions for living and high adaptability. It was concluded that the abundance and biomass of benthic macroinvertebrates in station 1 was lower than other stations which was related to fish cage culture activity and its effects on benthic macroinvertebrates. So it is suggested that each mariculture activity in southern coasts of Caspian Sea should be carried out with regarding to environmental considerations and performance of comparative evaluation project of environmental effects