JOURNAL OF THE PERSIAN GULF (MARINE SCIENCE)
Year:2011 | Volume:2 | Issue:6|Papers Count:7

Histological changes and maturity stages during the reproductive cycle of the ovaries of Klunzinger's Mullet (Liza klunzingeri) were investigated. The evaluation of the spawning season was carried out based on monthly samples from 3 stations in the Persian Gulf and the Oman Sea. Sex ratio was approximately 1:3 (M: F). The maturity stages of female L. Kluningeri are: Virgin, Developing Virgin, Developing, Developed, Gravid and Spent. Observations on seasonal maturity stages indicated that the species had a spawning period from November to March. The highest and the lowest gonadosomatic index (GSI) of 6.03 and 0.28 occurred in December and May, respectively. Individuals reached 50% maturity at 15.4 cm Total Length (TL). Histological analyses indicated group synchronous ovarian development occurred in L. klunzingeri.

A Cochlodinium polykrikoides red tide occurred in northern coastal waters of the Persian Gulf which killed million tons of fish and benthic animals. This study reports high mortality rate of Solen dactylus (razor clam) populations on the Golshahr coast of Bandar Abbas to show that management and monitoring plans are necessary to prevent future mass mortalities. Specimens of S. dactylus were collected during the red tide for three months in November 2008, February and April 2009. In April 2009, no clams were found in this area because all clams had died before the investigation. Abundance of razor clams showed no significant relationship with sea-surface physical and chemical factors such as sea-surface temperature, salinity, dissolved oxygen and pH (p ³0.05). Total weight of razor clams was not significantly different between November 2008 and February 2008 (p³0.05), however, the gonad weight of razor clams in February 2009 was significantly lower than that in February 2008 (p£0.05).

In order to study of kidney tubules, twenty specimen of 45 days old juvenile grouper (Epinephelus coioides) were prepared after proper biometry. Five mm thick sections were removed from the middle and posterior end of the kidney and fixed in Bouin and glutaraldehyde. The routine procedures of preparation of tissues were followed for light and transmission electron microscopic study. In macroscopic observations, it was observed that kidney was located retroperitoneal and attached to the vertebral column with an average length of 4±0.2 cm. The microscopic results showed that nephrons consisted of glomerules, proximal, distal and collective tubules. The proximal tubules were detectable with their brush border. Distal tubules had cuboidal cells with round nucleus that were positioned in the middle part of the cell. The lumen of these tubules were PAS negative due to lack of brush border. Collecting tubules were also PAS negative as their cuboidal cells lacked brush border and their ellipsoid to round nuclei were positioned central to the cell. TEM analyses of sections showed more details of tubules structure, e.g. plasma membrane showed an extensive system of depressions in all tubules, except in collecting tubules.

In this study, concentration of 17 elements, including As, Ba, Cd, Co, Cu, Hg, Mn, Ni, Pb, Zn, Ca,Fe, Mg, Na, P, S, Si, as well as methylmercury in 31 surface sediments were assessed. The sampling stations were Gulf of Golestan, Miankale Island, Babolsar, Nowshahr and Anzali, which represented the most important harbors in the Golestan, Mazandaran and Gilan provinces in the southern parts of the Caspian Sea, respectively. Mercury and methylmercury concentrations in the surface sediments ranged from 10 to 44 and from levels below detection limit to 0.41 ng. g-1 d.w, respectively. The fraction of methylmercury accounted from 0.3 to 2.4 % of the total mercury content. Organic carbon contents varied from 0.26 % to 1.50 %. In this study, element concentrations in the sediments did not exceed the sediment quality guidelines and posed no environmental concerns, with the exception of nickel, which was in the moderate pollution range.

Fiddler crab females have two small feeding claws while males have only one, the other is enlarged and used as a weapon as well as a mate attraction signal. The study was conducted on the small intertidal fiddler crab Uca sindensis in the Abi estuary near Bandar Abbas on the Persian Gulf. Data were collected from September 2007 to August 2008 in order to cover a wide range of ecological conditions experienced by these crabs over the duration of a year. We considered whether males Uca sindensis have behaviorally or morphologically compensated for the loss of one feeding claw. Therefore we measured the sex ratio of surface-active crabs, the size of the feeding claws the amount of food processed and the feeding effort (male and female). We showed that males scoop up handfuls of sediment at approximately half the rate of females, but spend more time feeding than do females (70.41%). Males are slightly larger than females, but the relationship of feeding claw to carapace size is not linear: small females have relatively large feeding claws for their size, while large males have relatively large feeding claws for their size. Males and females process equivalent amounts of food on a daily basis. In order to compensate for the loss of one feeding claw, males need to spend a greater amount of time feeding.

The total lipid content and composition of fatty acids of the liver and muscles of wild and cultured male and female Acanthopagrus latus were determined by gas-liquid chromatography. There were quantitative differences between individual fatty acids in the tissues investigated depending on sex and location. In all the samples studied, sex and location considered, the principle saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) were palmitic (C16:0) and oleic (C18:1n-9) acids, respectively. The results showed that wild male fish muscle contained a higher level of n-3 polyunsaturated fatty acids (PUFA), particularly docosahexaenoic acids (DHA) and eicosapentaenoic acids (EPA), although cultured fish tissues of both sexes contained a higher level of n-6 PUFA, particularly linoleic acid (LA) and arachidonic acid (ARA). The results indicate that the Acanthopagrus latus can be a healthy component in the human diet.

Rocky intertidal organisms are facing pronounced fluctuations in environmental conditions even at small spatial and temporal scales. This heterogeneous habitat is a proper model system to investigate effects of physical parameters and their interactions on physiological performances of marine organisms. In the intertidal zone (especially in tidal pools), the temperature and salinity usually increase in concert during the daytime low tides. In this study, we used a rocky intertidal scavenger gastropod, Nassarius deshayesianus, as a model to test if high salinity can affect the metabolic performance of rocky intertidal mobile ectotherms at high temperatures. In August 2009, specimens were exposed to normal and elevated temperatures and salinities for 50 minutes and their specific metabolic rates were evaluated (N=12). At the high temperature treatment, metabolic rates were significantly lower when the salinity was high. Considering the concept of oxygen- and capacity- limited thermal tolerance, we will discuss that this antagonistic effect of increased salinity on the aerobic performance at the high temperature may lower thermal tolerance of intertidal ectotherms. Also N. deshayesianus showed high mortality after a few days of exposure to 36oC water temperature. This signifies that they may currently live close to the maximum limit of thermal tolerance in the hottest sea of the world, the Persian Gulf.