Mesopotamian Journal of Marine Science

A total of 713 fish specimens belonging to 26 species and nine families from the Red Sea, Yemeni coastal waters were examined for the infection with trypanorhynchid cestodes during the period from September 2008 till February 2010. The results showed the occurrence of five different trypanorhynchids in viscera, body cavity and flesh of 12 fish species. These cestodes were: Pseudotobothrium dipsacum, Callitetrarhynchus gracilis, Floriceps minacanthus, Pseudogrillotia sp. and Nybelinia bisulcata. The first three species are recorded here for the first time in fishes from Yemeni waters of the Red Sea. Also, two fish species (Lethrinus mahsena and Valamugil seheli) are considered as new hosts for N. bisulcata in the Yemeni waters of the Red Sea. C. gracilis was found in nine different fish species. Five fish species (Pomodasys argenteus, Lethrinus lentjan, L. nebulosus, Scomberomorus commerson and Thunnus tonggol) harbored three trypanorhynchids (P. dipsacum, C. gracilis and N. bisulcata) in their muscles. Among fishes, both L. lentjan and T. tonggol were the most infected hosts, as each of them harbors three different trypanorhynchids.

The present study discussed the quantitative analysis of Transverse River Profile (TRP) on Shatt Al-Arab channel, by deriving several TRP parameters that can be easily quantifiable and comparable. These parameters are useful to detect the morphotectonic indicators of Shatt Al-Arab basin. Five cross sectional profiles were considered from the previous bathymetrical surveys of Shatt Al-Arab channel starting from Qurna (upstream) at the confluence of Tigris and Euphrates rivers towards Fao (downstream). The results illustrated the main rate of controlling the tectonic activity along the river channel by forming of islands bar at the middle of main river course and increasing in its meanders. The applied analytical technique also efficient in detecting the neotectonic activities for subsurface structures and their effects on deflecting and meanders of the river basin.

This study was carried out on juvenile Cyprinus carpio (L.) to investigate the effects of sub-lethal concentrations of copper and cadmium (0.1, 0.25, 0.4 ppm) on the survival rate, oxygen consumption and histopathological changes in the gills of exposed fish. The results showed a decrease in survival rate with increasing concentration of each metal. Copper has the most toxic effect compared with cadmium, the survival rate has decreased from 50% to 10% for copper and from 70% to 20% for cadmium with increasing concentration for 15 days. The half lethal time (LT50) was (14 and >15) days for copper and cadmium, respectively. Oxygen consumption rate decreased with increasing concentration and there was a negative correlation between oxygen consumption and metal concentration. The exposure to each metal caused histopathological changes in the gill and resulted in separation of epithelial secondary gill lamellae, hyperplasia, fusion of secondary lamellae and necrosis.

Food composition of three cyprinid larvae (Cyprinus carpio, Carassius auratus and Alburnus mosulensis) in Al-Huwaiza marsh has been studied during March and April 2006. The diet of these cyprinid larvae were consist mainly of zooplankton dominated by copepods both adult and larval stages followed by Cladocera Rotifera, aquatic insects and Ostracoda. The food of plant origin also exists and consists of diatoms and filamentous algae. Costello graphical plot showed that these larvae are generalist feeders. This strategy result in lower competition and allow these three species to co-occur in relatively high density in this marsh area. The food similarity between C. carpio and C. auratus was 0.60, between C. carpio and A. mosulensis was 0.44, while it was 0.72 between C. auratus and A. mosulensis. The food overlap analysis showed that C. carpio; C. auratus and A. mosulensis larvae share a wide range of prey types. Competition for food is possible However, direct competition seemed to be avoided to some extent as a result of great food availability in Al-Huwaiza marsh which makes it as a suitable nursery and feeding site for many cyprinid fish.

A Semi- automated flow injection analysis (FIA) unit was build-up for determination of ammonium ion in water samples from the Shatt Al-Arab River during the period from October 2009 to September 2010. The ammonium concentrations in water have been measured, at each of the eight stations (Qurnah (Tigres), Qurnah (Euphrates), Saad Bridge, Garmat Ali, Ashar, Abu Al-Khaseeb, Al-Seeba and Fao), monthly. The results indicated that (NH4+) concentrations increasing during May, June and July, 2010 especially in stations 5 and 6 were 0.95, 1.35 µg/ml , 1.30, 1.25 µg/ml and 1.45, 1.40 µg/ml, respectively. The FIA unit was applied successfully for the determination of ammonium in Shatt Al-Arab water sample and provide simple, fast, and reproducible methods for ammonium determination in water.

The marine calanoid copepod Pseudodiaptomus c.f. ardjuna (Brehm, 1953) was recorded from some freshwater habitats in some regions of the Shatt A-Arab River during March – July 2009. These regions include Al-Kurnish area, Al-Sindebad Island during April-August 2009 and at Al-Gurna city on March 2009 only. The species is briefly described in this work and its morphological characters are compared with earlier descriptions from Iraqi coastal water, like the total length of female and male, body shape, female genital segment, the shape of the male posterior prosomal segment and number of the setae of the furcal rami.

This paper evaluates the production pattern and economics of freshwater prawn (Macrobrachium rosenbergii) farming in seasonally saline rice fields in Bangladesh. The reconnaissance survey was conducted on 30 rice-prawn ghers (RPG) in south-west region of Bangladesh. The farmers were found to use their rice fields for farming prawn and rice (aman) concurrently from April/May to January, and for only rice (boro) from January to April. In the RPG farming system, farmers use rain water during wet season, and underground water with salinity of 1-5 ‰ during dry season. The average production of prawn, aman, and boro was recorded as 439.79±90.46, 3155.48±397.33, 4778.54±389.37 kg/ha/yr, respectively. The economic analysis show potentially good return, and the net return and benefit-cost ratio were US$ 1078.35 and 1.25, respectively. The payback period was determined as 9.37 years. The study implies that the culture of prawn in seasonally saline paddy field is economically viable.

Mangroves are highly productive wetland ecosystems and extremely important coastal resources providing a variety of environmental goods and services, which are vital to our socio-economic development. To evaluate the role of mangroves, a total of 75 semi-structured interviews were conducted with coastal community, resource user, government official, NGO personnel, researchers, and private entrepreneur to gather primary and secondary information. Results indicated that in the past 30 years there has been planted about 1,460 ha of euryhaline mangroves under different management regimes. Teknaf peninsula mangrove influenced two key variables viz., productivity and physical structure which direct other ecological processes. The variable ‘productivity’ provide suitable habitat for nursery, growth, migration through recycling waste and nutrients. The respondents identified 13 mangrove resource user groups in Teknaf peninsula which shows high dependency to mangroves goods. The catch of finfishes, shrimps and prawns, crabs, molluscs, etc. from the mangroves area contributes value to the small-scale fisheries. The knowledge gained from the information content of the Teknaf peninsula mangroves ecosystem contributes value to scientific and educational community. In particular, it means that environmental goods and services provided by the Teknaf peninsula mangroves are rarely produced independently and the multiple interdependencies involved in providing such environmental supports.