Structure and diversity in Mytilus californianus (Mollusca: Bivalvia) communities

Mytilus californianus (Mollusca: Bivalvia), the California marine mussel, occurs in intertidal populations so derise that they are referred to as "Mussel beds." The mussel beds range in physical complexity from structurally simple, essentially mono-layered assemblages, to structurally complex, multi-layered assemblages. The internal environment within the bed varies accordingly. The mussel bed provides either directly or indirectly, habitat, food and shelter for a large community of associated invertebrates. This study examines the relationship between physical complexity of the mussel bed habitat and composition of the associated community.

Effects of trawling for ocean shrimp (Pandalus jordani) on macroinvertebrate abundance and diversity at four sites near Nehalem Bank, Oregon

Surveys with a remotely operated vehicle (ROV) at four mudhabitat sites with different histories of ocean shrimp (Pandalus jordani) trawling showed measurable effects of trawling on macroinvertebrate abundance and diversity. Densities of the sea whip (Halipteris spp., P<0.01), the flat mud star (Luidia foliolata, P< 0.001), unidentified Asteroidea (P<0.05), and squat lobsters (unidentified Galathoidea, P<0.001) were lower at heavily trawled (HT) sites, as was invertebrate diversity based on the Shannon-Wiener index. Sea cucumbers (unidentified Holothuroidea) and unidentified corals (Hydrocoralia) were observed at lightly trawled (LT) sites but not at HT sites. Hagfish (Eptatretus spp.) burrows were the dominant structural feature of the sediment surface at all sites and were more abundant at the HT sites (P<0.05), a result potentially related to effects from fishery discards. Substantial heterogeneity was found between the northern and southern site pairs, indicating high site-to-site variability in macroinvertebrate densities in these deep (146–156 m) mud habitats. Two of the study sites were closed to trawling in June 2006. The data from this study can be used in combination with future surveys to measure recovery rates of deep, mud, seaf loor habitats from the effects of trawling, thus providing a critical piece of information for ecosystem-based management.

Impacts of fish sanctuaries on the production and diversity of plankton on beels of haor region in Bangladesh

The experiment was carried out to study the impacts of fish sanctuaries on the production and diversity of plankton in beels of haor region at Mithamain Upazila of Kishoreganj district in Bangladesh during July 2004 to June 2005. A total of 75 (60 phyto and 15 zooplankton) and 74 (59 phyto and 15 zooplankton) genera of plankton were recorded in T-1 and T-2 (with sanctuary) respectively while only 50 (39 phyto and 11 zooplankton) genera were obtained in T-3 (control). Chlorophyceae and Copepoda were the most dominant group of phytoplankton and zooplankton respectively in all the treatments. The total phytoplankton numbers were found to range from 5472 to 35,833 cells/l and 5250 to 40,472 cells/l and total zooplankton from 667 to 1722 cells/l and 611 to 1667 cells/l in T-1 and T-2 respectively in sanctuary sites whereas the ranges of phytoplankton and zooplankton in the control site were 1778 to 29,333 cells/l and 56 to 1056 cells/l respectively. The maximum phytoplankton and zooplankton were recorded during winter season in all the treatments. The ranges of total plankton were 6194 to 37,500 cells/l, 6028 to 41,806 cells/l and 1889 to 29,444 cells/l in T-1, T-2 and T-3 respectively. The phytoplankton, zooplankton and total plankton recorded in treatments with sanctuary were significantly higher (p<0.5) than the treatment without sanctuary (control) indicating positive impacts of sanctuaries on the production of plankton. Between two treatments of fish sanctuaries the total plankton populations were comparatively higher in T-2 than T-1.

Heroin impairs map-picture-following and memory tasks dependent on gender and orientation of the tasks

Male and female heroin-dependent patients (HDPs) matched with "normal" people were tested on 4 topographical orientation tasks: schematic map-following, map-memory, schematic picture-following, and picture-memory tasks. The results showed that, in general

Investigation on the ecological impact of constructing and activities of petrochemical industries of petrochemical special economic zone of Mahshahr on the abundance and diversity of macrobenthic fauna in Jafari Creek, north-west of the Persian Gulf

The impact of Petrochemical Special Economic Zone (PETZONE) activities on the health status of Jafari Creek was studied by assessing the changes in macroinvertebrate assemblages in nine sites during September 2006- January 2008. Furthermore to evaluate the ecological status of the Jafari Creek the WFD indices (i.e. AMBI, M-AMBI) were used. The relationship between spatial pattern of macro invertebrate assemblages and ambient factors (i.e. water temperature, salinity, pH, dissolved oxygen, turbidity, electrical conductivity, total dissolved solid, total hardness, total nitrogen, ammonia, total phosphorous, chemical oxygen demand, biological oxygen demand, sediment grain size distribution, sediment organic content, heavy metals contents) was measured. Background Enrichment indices, Contamination factor and Contamination degree, were used to assess the health status in the study area based on Nickel, Lead, Cadmium and Mercury contents of the sediments. The macrobenthic communities had a low diversity and were dominated by opportunistic taxa, and the AMBI and M-AMBI indices need to be calibrated before using in Persian Gulf and its coastal waters. The BIO-ENV analysis identified pH, dissolved oxygen, TDS, and the total organic content of sediments as the major environmental variables influencing the infaunal pattern. This suggests that management should attempt to ensure minimal disturbance to environmental variables underlying the spatial variation in macroinvertebrate assemblages. Background Enrichment indices showed that the health of Jafari Creek has declined over time due to the constant discharge of heavy metals to the Creek system. Furthermore WQS index shows that the quality condition of the water column in Jafari Creek, regard to the calculated number (3) is week. These indices also identified a significant degree of pollution in the study area. The decrease in the ecological potential of Jafari Creek was best highlighted by the alteration in macrobenthic assemblages.

Ecological impact of Mahshahr petrochemical activities on abundance and diversity of macrobenthic fauna in Zangi Creek (Persian Gulf)

The Moosa Creek extends from its opening into the Persian Gulf, with some sub narrow creeks leading to it. Zangi creek is one of the main branches of Moosa creek. The creek contains numerous sources of organic pollution, including sewage outlet flows and boat waste. After establishing the Petrochemical special Economic Zone (PETZONE) in 1997 near to the Zangi Creek, the pipelines, streets and railway made it distinct from eastern and western parts of this creek. Industrial activities have released sludge and effluents in this creek along these years. A survey of the Zangi creek was performed, assessing water properties, organic pollution, and the population density, distribution and diversity of macrobenthic fauna through bi-monthly sampling from July 2006 to September 2007. Samples were collected from water near the bottom and sediment at 7 stations include 2 stations inside the distinct Zangi creek and 4 stations along a transect with 1 km distances between them in eastern free part and one reference station located at the Persian Gulf entrance to the Moosa creek. The environmental parameters such as temperature, salinity, pH, dissolved oxygen, COD, turbidity, EC and heavy metals include Hg, Cd, Pb, Ni as well as percentage silt-clay and total organic matter of the sediment were measured. The faunal population density and their distribution are discussed in relation to the environmental changes. Results showed spatial heterogeneity in faunal distribution of the Zangi creek. Nine groups of macrofauna were identified out of distinct zangi creek. Polychaets formed the dominant group (48%) followed by bivalves (13%), gastropods (10%), Decapods (2%), Tanaids (5%), and all other groups (22%). The distinct creek was heavily polluted without any macrofauna communities probably as a consequence of the high pH, COD, low salinity and heavy metals contamination specially Cd and Pb. The other stations near to the disposal site were found with macrofauna communities commonly tolerant to organic pollution, At 3 km east of the disposal site, macrofauna is comparable to the surrounded creek, whereas macrofauna still indicate environmental degradation. Farther a way, faunal density decreases and equilibrium taxa gradually replace opportunistic species, while the other stations were far from polluted area contained lower pollution and relatively healthy macrofauna. The mean biomass of macrobenthic fauna were estimated for the whole studied area. The results are considered in Minimum density and biomass in surrounded creek and maximum density and biomass in 3 km of surrounded area. Biodiversity Indices were low in surrounded creek. The Shanon-weaver information index was used to describe the spatially variations in diversity. Macrofauna density, shanon and simpson index were significantly variable between surrounded and free parts of Zangi creek (p<0.05). The numerical abundance of macrobenthose varied from 221. m-2 in polluted area to 4346 m-2 in free part of Zangi creek. The Shanon-weaver information index varied from 0.4 in distinct area to 2.9 in reference station. The physico- chemical changes between distinct and free creeks showed significant variations such as pH, salinity and EC. Salinity and EC were significantly positive correlate to macrofauna density, whereas pH and TOM percentage indicated significantly negative correlation to density. Heavy metals concentrations in sediments were higher than water samples. Concentration pattern of heavy metals in sediments and water samples were Ni>Pb>Cd>Hg. Salinity and pH were significantly correlated to metals in sediments (p<0.01). No significant correlation were found between Macrofauna density and heavy metals (p<0.05).