Iraqi Journal of Aquaculture

Several studies have been conducted on aquatic insects in southern Iraq that included various taxonomic, biological and ecological aspects of the larval and adult stages in aquatic environments, which reflects their abundance and important role in the societies and ecosystems inhabited by them. They serve as adequate food for groups of predatory vertebrates and invertebrates. The studies included the environments of the Shatt al-Arab River and its branches, temporary and permanent ponds emanating from them, as well as some areas of the marshes. Aquatic insects play an important nutritional role, as many types of fish depend on them and form an important link for energy transfer from the bottom to the top in the food web because many types of them show a wide difference in their feeding habitats, so their importance lies in the interconnected ecosystems in creating an ecological balance within the rings of the food chain. The ability of aquatic insects to increase their reproduction rates make them excellent model for analyzing the structure and function of the freshwater ecosystem. Some of their species that spend part of their life in water have been used as ecological indicators in determining the state of aquatic environments and estimating environmental risks as they are greatly affected by the state of the environment in which they live. It is one of the most affected individuals in terms of surface water pollution.

This study is concerned with the concentrates of heavy metals (Cd , Pb and Zn ) that is found in Lisa subviridis fish, which were collected on April 2017 to September 2018, it is brought from the Iraqi seawater, samples of fish were dried by (Deep Freeze Drier), ash was estimated by furnace and then digested by Nitric acid, after digesting the samples were diluted and the above heavy metals were estimated by Flame Atomic Absorption Spectroscopy, the results shows that the upper values of estimated heavy metals concentrates (Cd, Pb and Zn) were recorded in August 2017 it was o.o48,0.062 and 0.042 mg/gm respectively, while Cd shows less recorded value in February 2018, Pb and Zn recorded less values in April and May 2018, it was 0.045 and 0.023 mg/gm respectively.

The current study was conducted on N. indica in three stations for the period from December 2017 to November 2018 (Al-Sharsh, Al-Salhiya and Al-Dweab), as samples were collected monthly. Some environ-mental factors were calculated, such as water temperature. The lowest water temperature was 12 °C during January and the highest temp-erature was 33 °C during July, both in Al-Salhiya station. The lowest value of salinity was 0.5‰ reached in April and November in Al-Sharsh station, while reached highest value ‰ 39.3 were recorded during July for Al-Dweab station, the light transmittance values ranged between 63-18 cm, recorded during July and November for Al-Salhiya and Al-Sharsh stations, respectively. As for the values of dissolved oxygen, it ranged between 12.1-5.1 mg/l during August and May in the two stations Al-Salhiya and Al-Sharsh, respectively. As for the bottom sediments of all the stations, they were alluvial with few and different percentages of sand and clay. The study showed that the studied environmental factors have an impact on the distribution and spread of this species within the horizontal and vertical sections in the tidal zone. The total density and density were measured within the horizontal distribution pattern in each station and the monthly total density ranges were 592-32 individuals/m2. The density of the three species was calculated within the horizontal distribution after dividing the area into three sections for each station. The results of the study indicated that there were significant differences at the level of P<0.05 for densities between the first and second different sections of N. indica, and there were significant differences between the first and third sections and between the second and third sections.

The ecology of Rotifera was studied at three stations in southren
Shatt Al-Arab River included: St.1- Al-Ashar, St.2- Abul Khasib and
St.3- Al-Fao, during 2013. Seasonal horizontal samples were taken
by a plankton net with a mesh-size of 53-µm. Density of Rotifera
fluctuated between 0-113.3 ind./L registered at all station. Eighteen
taxa belonging to nine genera of Rotifera were encountered. Water
temperature values ranged between 15 and 27.5 degrees Celsius,
salinity values were registered 1.8-40 g/L, pH values ranged
between 6.2 and 8.7, and the dissolved oxygen values ranged
between 5.1 and 9.9 mg/L. TDS values fluctuated between 1467 and
33590 mg/L, while the turbidity values ranged between 7.1 and
180.6 FTU. Data were statistically analyzed using SPSS and
CANOCO (CCA) software, which showed a positive correlation
between most of the recorded species and some environmental
factors on the one hand, and between most of the environmental
factors in the three studied stations.

The Homopolysaccharide called beta-glucan was extracted from different sources, microbial source (baking yeast of Turkish origin) and vegetable source (brown barley bran) using the classical method and hot water method respectively. The results showed that the higher levels of β-glucan, reaching 5.95% and 5.18%, were found respectively in baker's yeast of Turkish origin and in barley bran. The β-glucan was analyzed by Fourier transform infrared spectroscopy (FT-IR) and the result confirmed that the extracted glucan showed a high degree of similarity and purity as compared with the standard, The β-glucan was added to the fish patties at different ratio (0, 0.1, 0.3, 0.5, 1) gm\25gm patties, and storage patties at 4 °C for 14 days. Effect of addition of different levels of β-glucan from both sources on inhibition of the bacterial counts for fish patties during storage (14 days) was studied, the total counts of bacteria was decreased with increasing the ratios of β-glucan up to 1%, the ability of the extracted β-glucan from barley bran to inhibit the total bacterial count, psychrophilic bacteria and coliform bacteria was greater than that the extracted β-glucan from yeast.

Some phenotypic characteristics of the Hepu mitten crabs, Eriocheir hepuensis, were studied, Eighty individuals of the crab males and females were collected from Shatt Al-Arab River. The width of the carapace ranged from 4.2-9.4 cm and 3.4-8.8 cm, and their wet weights ranged from 76.17-299.34 g and 92.27 199.27 g for males and females respectively. The study aims at finding the relationship between the carapace width and wet and dry weights, ash and organic matter as well as finding a relationship between the length of the chela and dry weights, ash and organic matter in the Shatt Al-Arab, as it is now possible to extract the length and width of the carapace without directly calculating them, but by relying on weight. The results showed high significant differences between the width of the carapace with wet and dry weights, ash and organic matter as well as a correlation between the length of cheliped with dry weight and the weight of ash and organic matter. It is noted that there is a strong to weak correlation at the probability level of 0.05 between cheliped length and dry weight ash and organic matter.