جستجوی مقالات مرتبط با کلیدواژه « بندرانزلی » در نشریات گروه « محیط زیست »

This study carried out in order to investigate the impact of Bandar Anzali's breakwater on the diversity and abundance of Macro-invertebrates. Twelve stations were located in two sides of the breakwater in the wall and in the sea substrate. The sampling carried out from November 2017 until August 2018, seasonally. In the substrate stations on the sea side, the bivalve species Cerastoderma glaucum and Amphipod Stenogammarus compersus were observed in all stations with an average 344.1 ± 11.6 and 7.77±55.9 n.m-2, respectively. The worm species Streblospio gynobranchiata with abundance of 33.3 ± 42.5 n.m-2 was found only in the estuary section. Among the Macro- invertebrates on the breakwater wall; the Mytilaster lineatus and Mytilopsis leucophoeata were found on the sea side and in the estuary side, respectively. Their abundance had not significantly difference in different seasons. The Amphipoda Melita mirzajanii and Hediste diversicolor were also frequent in the wall of breakwater with 4106±1878 and 495±110 n.m-2, respectively. The crustacean and worms had more abundant in summer 2018 than other seasons. According to ecological indices, species diversity was more in the sea side rather than the estuary side for both habitats; the sea substrate and the wall. Furthermore, the species diversity was more in the wall of breakwater rather than sea substrate. The artificial constructs such as breakwater have an important role to increase of the species diversity.

Study of meroplankton structure, abundance variationsanddetermined of bloom them were assessed in different years and seasons in the offshore Anzali, at the 4 stations. The samples have taken seasonal at the 5, 10, 20 and 50 m depth in 1996 and between 2001 and 2013. The fifteen meroplankton groups were identified. In the study, dominant meroplankton were Bivalvia larvae, Balanus improvisus and  Nereis diversicolor. The abundance of Bivalvia larvae increased sharply in 1996, average abundance of Bivalvia larvae was measured about 26000 ind.m-3. There were increased and declined in Balanus improvisus abundance after Mnemiopsis leidyi bloom between 2001 and 2013.The abundance of B. improvises varied from 98 to 4700 ind.m-3 in 2001 and 2010, respectively. In addition, the bloom of B. improvises was recorded amount 3100 ind.m-3 in spring. The abundance of N. diversicolor varied between 60 and 1500 ind.m-3 in 2001 and 2006, respectively. The N. diversicolor did not show before M. leidyi bloom (1996). The seasonal bloom of N. diversicolor was observed amount 500 ind.m-3 in summer. The vectoral distribution of meroplankton was observed at 50 m depth in surface layers. The finding displayed, meroplankton abundance decreased from inshore to off shore. The environmental parameters and exotic species could be important reason in temporal and spatial of meroplankton in the southern Caspian Sea.