JOURNAL OF THE PERSIAN GULF (MARINE SCIENCE)
Year:2011 | Volume:2 | Issue:3|Papers Count:7

Vertical distribution of zooplankton biomass and abundance, copepod taxonomic composition and species diversity were analyzed at eight stations during an oceanographic expedition along the Straits of Malacca. Samples were collected in vertical hauls (140 mm mesh using 45 cm diameter NORPAC net) from four depth strata. Zooplankton biomass was higher at 10-20 m depth in the central and southern parts of the Straits compared to the other depth layers, but the differences were significant (p<0.05) only in the southern part. A total of 96 species of planktonic copepods belonging to 35 genera were identified in the surveyed area. Except for the 10-20 m depth layer in the northern part of the Straits, copepods were the major fraction of the total zooplankton at all depths. In the northern and central parts of the Straits, the deeper layers had higher species diversity indices than in the surface waters, mainly due to higher evenness in the deeper layers. The lower species diversity in the deeper layers of the southern region was attributed to the dominance of a few species.

Ichthyoplankton data provide a base for research into population dynamics of major fishery species. Information on ichthyoplankton ecology forms an important component of stock assessment and fishery management plans. Also, nursery areas are important regions for the recruitment success of fishery stocks, and as such, conservation of these areas is a key part of fishery management. Temporal distribution and composition of ichthyoplankton of in Northwest of the Persian Gulf were analyzed. Khure Mussa Inlet is affected by direct and indirect human activities related to petrochemical plants, harbor facilities and other economic ventures. Samples were taken from eight stations during March 2007 to April 2008.A total of 9440 larvae were collected. The highest density of larvae was observed in April 2008 (1288.88±610.32 larvae/10m2). Higher mean densities occurred during the warmest month. Fish larvae from 23 families were identified, Gobiidae, Clupeidae, Sparidae, Sciaenidae and Sillaginidae were the most representative during the study period. Temporal variations in abundance of larvae showed different reproduction patterns for species. Furthermore, the spatial distribution was different for larvae. Cluster analysis using the Bray-Curtis similarity index revealed well-defined groups of stations and assemblages of larvae. For visualizing the results, spatial distribution and density data were shown on regional maps using GIS software.

In this research we assessed the concentration of total mercury in the muscle, liver and gill tissues of Indian spiny turbot, Psettodes erumei caught from Jask coastal waters in Hormozgan province. Fifteen fish specimen were caught using trawl in spring season 2008. After biometrical measurements and sex determination, muscle, liver and gill tissues were collected, mercury was extracted from the tissues using chemical digestion method with pure nitric acid and its concentration was determined using AAS. The mean concentration of Mercury among body parts, but not between males and females, showed significant differences (P<0.05). The analyses of results using one way t-test showed that muscle and liver contained the lowest and the highest concentration of Hg, respectively. The concentration of Hg in gill was 19.98±1.35 mg.Kg-1 dw. The analyses of results showed that concentration of total Hg in muscle tissue was lower than the limit set by WHO, FAO and UKMAFF standards. Mercury content in sediment samples compared with American and Canadian standards and was lower than that of ERM, PEL, SEL and greater than that of SQRT, ISQG, ERL, and LEL standards.

It is shown that Saharan soil has the potential of producing bioavailable iron when illuminated with visible light and also it contains some essential macronutrient and micronutrient elements. In this study, these properties of the desert soil were tested on the certified wheat cultivars (Triticum aestivum L. var. gonen 98) using Hewitt nutrient solution, illuminated and non-illuminated soil solutions from Sahran desert and Ankara city and Zabol. Deionized water was used as a control solution. Wheat cultivar, displayed comparable results when grown in illuminated Saharan dust solutions and Hewitt solution. Results showed that dust from Saharan desert could act as a source of natural fertilizer under specific conditions and could be utilized in "true" organic farming.

As with all coral reef systems, the ecology of Ningaloo Reef is closely linked to water circulation which transport and disperse key material such as nutrients and larvae. Circulation on coral reefs may be driven by a number of forcing mechanisms including waves, tides, wind, and buoyancy effects. Surface waves interacting with reefs have long been known to dominate the currents on many coral reefs. This forcing is provided by wave breaking on the forereef that causes a local increase in the mean sea level (the “setup”) that is responsible for driving the cross-reef flow. For this project, we are developing a coupled wave-circulation numerical model of Ningaloo Marine Park-located in northeast of Australia, using an extensive field data set collected from April-May 2006 in an ~5 km region around Sandy Bay, to validate its performance. The analysis of field data collected on the forereef, reef flat and in the channel revealed a strong correlation between the incident wave height and currents inside the reef lagoon and channel. A nearshore numerical wave model (SWAN) which simulates wave transformation due to the effects of shoaling, refraction, diffraction, and dissipation by both bottom friction and wave breaking was chosen to simulate waves across the system. The model uses a finely-resolved computational grid (~20 m resolution on the reef) and incorporates high resolution bathymetric data provided from hyperspectral imagery. The model is forced with offshore wave conditions measured during the 2006 field campaign and model output is compared with an array of wave gauges deployed along cross-reef transects from the forereef slope to the lagoon. Following successful validation, results from SWAN, particularly the 2D radiation stress gradients, are used by the circulation model to include the wave-driven circulation.

Plants are known to bioaccumulate many contaminants. Petroleum-derived compounds, such as saturated hydrocarbons and PAHs are widespread persistent environmental contaminants. Deposition of soot and precipitation of black rain have occurred in the Shadegan Wetland. In this study, PAHs in plant parts of two prominent species of halophytes, Halocnemum strobilaceum and Suaeda maritima were determined. PAHs were found in plant parts of H. strobilaceum and S. maritima. PAHs quantities differed significantly between shoots and roots of plants and between H. strobilaceum and S. maritima. Concentration of these compounds was greater in plants growing in the southern part of the wetland (south of Abadan-Mahshar road) than those growing at the northern part. This finding corroborates findings of investigation on prevalence of heavy metals associated with crude oil, for example, Ni and V in sediments of Shadegan wetland. Detecting PAHs in plant organs indicates the potential for their bioaccumulation and transfer in trophic levels in the food chain. Although, determining threshold levels for ill-effects of PAHs, such as reduction in vegetation coverage area, plant growth and development, physiological and metabolic changes as well as changes in biodiversity indices, require further investigation, the bioaccumulation by plants and subsequent removal of such plants from contaminated areas, the wetland ecosystem could recover itself in few years.

Qeshm Channel is a shallow and narrow waterway located between Qeshm Island and the mainland in the vicinity of Hormuzgan Province, Islamic Republic of Iran. This channel is important because of its economic, industrial, fisheries and navigation role it plays as well as environmental issues it presents in the region. A prognostic study was performed to simulate currents in this channel, using COHERENS model. This model is a three-dimensional hydrodynamic model. Simulation of currents was carried out in 20 sigma levels from the seabed to the water surface during one month. It was assumed that the variations of seawater temperature and salinity, four main tidal constituents and the regional wind were the most effective factors in the numerical simulation. Finally, sensitivity analysis was carried out for each factor and the outputs of simulation were verified using the field data recorded by the experts from Iranian National Center for Oceanography. Very good agreements were found between the numerical results and the field data.