A survey of algal bloom impacts on abundance and distribution of macro benthos in Hormozgan province coastal waters

Abstract

The investigation of the algal bloom effects on Macro benthos abundance and diversity was seasonally carried out in coastline waters of Hormozgan province in 1391. Fourteen stations were selected for sampling; as 8 stations in coast of Bandar Abbas, 3 in Jask Port (east of Hormozgan) and 3 stations in Lengeh Port (west of Hormozgan). Polychaets, oligochaets, mollusks, crustacean and others like nematodes, nemertean’s, foraminifera’s, and ophiuroides were identified. Crustacean with 333950 ind.-2 were dominant group whereas nemertean with 5050 ind.-2 were minimum in density. Results showed that mean abundance of macro benthos was at most in spring (5614±3992 end) -2 and with 1244±380 ind.-2 was at least in autumn. Related results to stations showed that mean abundance in Jask Port and Lengeh Port were more than Bandar Abbas City. Among 8 stations in Bandar Abbas, Langargah with 168±977 ind. -2 was at most and Posht-e- shahr was at least in abundance (82±256 ind. -2). In Lengeh and Jask ports the stations far from coasts showed more abundance than station near coast. Monthly investigation showed that Macro benthos community was much more in April with 1011±6783 ind.-2 than December with 6±28 ind.-2 , respectively. Shannon -Winner diversity index was low (0.61.2) in three stations, Evenness ranged from 0.1 to 0.4 and Margalof ranged from 2 to 4. Among four stations, mean wet weight varied from 12.18±6/95 gr in Jask Port (maximum) to 6.24±3/85gr in Bandar Abbas (minimum) .Seasonally, in spring the wet weight of macro benthos was 15.15±16/32 (maximum) and with 1.43±0.88 gr showed the minimum value in summer. There was a negative correlation between silt and macro benthos abundance and a positive correlation existed between macro benthos community and sand. There was no significant correlation between macro benthos community and TOM. To pay attention to results like diversity, abundance, wet biomass and correlation; it seems that algal bloom has no obvious negative effect on Macro benthos communities.