شناسه هاي افزوده :
فضلي،حسن ، همكارطرح , حسين زاده صحافي، همايون ، همكارطرح , نصرا..زاده، حسن ، همكارطرح , فارابي، محمد ، همكارطرح , پورغلام، رضا ، همكارطرح , روحي، ابوالقاسم ، همكارطرح , سليماني رودي، عبدا.. ، همكارطرح , هاشميان،عبدا.. ، همكارطرح , رامين، محمود ، همكارطرح , تهامي، فاطمه السادات ، همكارطرح , روشن طبري، مژگان ، همكارطرح , نادري، مهدي ، همكارطرح , دريانبرد، رضا ، همكارطرح , گنجيان، علي ، همكارطرح , مكرمي، علي ، همكارطرح , مخلوق، آسيه ، همكارطرح , خداپرست، نوربخش ، همكارطرح , بهمنش ،شهرام ، همكارطرح , كيهان ثاني، عليرضا ، همكارطرح , نبوي،عيسي ، همكارطرح , عوفي، فريدون ، همكارطرح , رستميان، محمد تقي ، همكارطرح
چكيده انگليسي :
This report is part of a project that has been implemented from 2008 to 2010 on the abundance, biomass and distribution of fish, phytoplankton, zooplankton, jellyfish and macrobenthos in the southern of the Caspian Sea. Sampling of plankton and macrobenthose community was seasonally conducted from the depths of 5, 10, 20, 50 and 100 m in transects along Astara to Gomishan. For catching fish used three methods by fishermen including beach seine (Pareh), gill nets and light funnel trap for fishing of bony fish, sturgeon and kilka fish, respectively. The purpose of this report was analyse the results before the establishment fish of cage culture in the southern part of the Caspian Sea. The results of phytoplankton showed that 8 phylum were identified comprise to Bacillariophyta, Pyrrophyta, Cyanophyta, Chlorophyta, Euglenophyt, Xantophyta, Chrysophyta, andHaptophyta. The number of species has decreased from 2008 to 2010 and from 191 to 181 species of the coefficient of variation was 5.23%. Therefore, Bacilartoria that dominates the phytoplankton population in terms of the number of species in the Caspian Sea for 97 species have been identified as the trend decline in 2008 to 81 species in 2010 to about 16.5% of the coefficient of variation (CV). Other phylum have had fluctuations in the number of species where the Chlorophyta from 28 species in 1387 to 31 species with a CV of 7.9%, Pyrophyta from 33 to 25 species with a CV 24.2 %, Cyanophyta from 25 species to 33 species with a CV of 24.2%, Euglenaphyta from 15 to 9 species of the CV of 40%, Crysophyta from 2 to 1 as the CV of 50% decreased, respectively. Abundance and biomass of phytoplankton in the upper and lower layer has significant different was 50 m away from the beach and increase the depth of the average abundance and biomass is reduced. The results showed that the abundance of phytoplankton increased in the transects of Astara, Babolsar, Anzali, Amirabad, Turkmen, Sefidroud, Noshahr and Tonekabon, respectively. Also, biomass to the transects of Astara, Anzali, Sefidroud, Babolsar , Noshahr, Tonekabon, Amirabad and Turkmen have higher levels of phytoplankton groups in areas where they represent a difficult situation Noshahr and Tonekabon abundance (grades 7 and 8) and biomass (grades 5 and 6) were found. The appearance of jellyfish in 2009, due to changes in the ecosystem of the Caspian Sea into the fauna and flora typical of the presence of some exotic species, harmful and toxic includes Cerataulina pelagica, Pseudonitzchia seriata, Nodularia spomigena, Pseudulunula sp. and Chrysochromulina sp. Mentioned that if the conditions for them to be provided with algae bloom in which they will be threatened species expressed Caspian Sea ecosystem. The status of zooplankton showed that Acartia tonsa was dominated zooplankton population, with more than 90% frequency in southern of the Caspian Sea in which coincided the A. tonsa that the alien spices list. The presence of such a dominant speciesin an ecosystem is a group of biological communities can account for the long term is harmful toother species where after the presence of M. leidyi activities that contribute to reducing the abundance and biomass of mussels play an important role in water filtration and has suspended filter feeders are barred. Survey the status of different fish species in the southern of the Caspian Sea showed that they have fluctuations in fishing and some of their species on the list of endangered (EN) and critically species (CR). The results of sturgeon showed that this fish in 2006 on the list of endangered species (Endangered species) were already down to a critical (Critically endangered), in which could be due to the loss of natural habitats for reproduction, overfishing, illegal catch), poaching, environmental pollution, reducing artificial propagation, the possibility of unavailability of food items and changed in the fauna of the Caspian Sea and the lack of a comprehensive program for the fishing year by the five Caspian Sea neighbors related. Also, stated that any manipulation of the closed ecosystem of the Caspian Sea will cause the change in population dynamics of Clupeidae. It would be because of this marine fish (Catadromous), eating plankton feeding behavior, reproductive strategies in surface water and float eggs is related. Therefore, any interference and manipulation in the depths (5-50m ) will increase the survival and sustainability of alien species, as this part of the coastal areas as feeding ground, spawning ground and nursering ground, and is located more affected by environmental pollutions.
In Conclusion, that during the last three decades there has been changes in the fauna and flora of the Caspian Sea mostly caused by human factors, and increase or decrease in some species, removal or replacement of some species, and food competition causing disturbance in the ecosystem of the Caspian Sea. So it is suggested that any fisheries exploitation operation of the Caspian Sea should carry out the project detailed Environmental Impact Assessment (EIA) factors and the impact (positive and negative) are identified and proceed. Based on the data obtained for the establishment of fish cage culture depth of 50m is recommended.
some zooplankton species extinct (e.g Eurytemora genus) or some of its populationhas declined sharply whereas the indicator species Eurytemora minor, E.grimmi introducedas amain food items for Clupeonella engrauliformes (Anchoy Kilka). Therefore, increase or decrease the abundance and biomass of zooplanktonin the depths, differentseasonsand the regionon the southern of the Caspian Seacould bedue to the presenceorabsence of jellyfish inthe regiondepend. The results showthat th eabundance and biomass of zooplankton from a depth of 5m high is a downward trend, whilst the highest abundance and biomass in all seasons at depths of 5-20m was found. The studies alsoshow thatthe abundance of zooplankton in spring is the season of renewal and growth and reproduction of organisms have been changed from 2008 to 2010, so that in the spring the highest number 28005(2008) to 7514 (2010) N/m3 with acoefficient of variation (CV) of73.2%, in autumnof8427(2008) 2283 (2010) N/m3with a CV of 72.9% and in winter 19030(2008) to8129 (2010) N/m3 with a CV of 57.3% was reduced. Therefore, according tothe coefficient of variationdecreased with average 67.8%ofthezooplankton abundance from2008 to 2010,an yir responsible manipulation on the Caspian Sea ecosystem caused irreparable damage on this group of organisms known asprimary consumerswill beconsidered.
The survey of comb jellyfish from 2008 to 2010 show that the average annual abundance and biomass has been decreasing, so that the 63 (2008) to 11 (2010) N/m3 and the biomass of 75.7g/m3 (1387) to 0.6 g/m3 (1389), in which the coefficient of variation of abundance and biomass decreased by 82.5% and 99.2%. Fluctuations in abundance and biomass of comb jellyfish in different seasons showed that the layer of water more than 20m were highest at all times. Totally, the population of comb jellyfish in the upper layer of less than 20m was about 98 and 87% in spring and winter, respectively. In summer and fall the frequency of jellyfish about 93% were observed in the upper layers of 20 m. The results showed that the abundance of the comb jellyfish at depths less than 20m have the highest frequency and even in the surface layer (0-20m) has a frequency of 18% was 50 m. The survey of benthic invertebrates showed that the average annual abundance of macrobenthos from 2008 to 2010 has been increased from 3980 to 4581N/m2 with CV of 13.1%, respectively wherever can be due to the presence of exotic species as Streblospio gynobranchiata, Spionidae family since the early 2009 into the Caspian Sea and the dominant benthic invertebrate population now. The results showed that the annual average biomass of benthic invertebrates has been decreasing from 36.932g/m2 (2008) to 12.125g/m2 (2010) with CV of 75.3%, it would be bivalve shellfish due to lower population abundance than the other groups of Cerastoderma lamarcki the size and impact of macro-benthic organisms that depend on biomass. Overall, the depth of 20m at most transects the maximum abundance was compared to the other depths. Therefore, with respect to the distribution and abundance of macrobenthos to 50m, especially non-native species S. gynobranchiata the nutritional part of deposit feeders and can play an important role in Bioturbation. So it is recommended that any aquaculture
Keywords: fish, phytoplankton, zooplankton, comb jellyfish, macrobenthos, Fish, cage, Caspian Sea
