Abstract. Al-Abbawy DAH, Al-Thahaibawi BMH, Al-Mayaly IKA, Younis KH. 2021. Assessment of some heavy metals in various aquatic plants of Al-Hawizeh Marsh, southern of Iraq. Biodiversitas 22: 338-345. In order to describe the degree of contamination of aquatic environments in Iraq, heavy metals analysis (Fe, Ni, Cr, Cd, Pb, and Zn) was conducted for six aquatic macrophytes from different locations of Al-Hawizeh Marsh in southern Iraq. The six species were Azolla filiculoides (floating plant), Ceratophyllum demersum, Potamogeton pectinatus, Najas marina (submerged plants), Phragmites australis, and Typha domingensis (emergent plants). The results indicate that cadmium, chromium, and iron concentrations in aquatic plants were above the World Health Organization (WHO). In contrast, zinc, copper, and lead were within the allowable limits. C. demersum and N. marina showed higher concentrations of heavy metal accumulation than the other aquatic plants. The concentration of heavy metals in plant tissues during the summer months was higher than in the different seasons. C. demersum and N. marina showed higher concentrations of heavy metal accumulation than the other aquatic plants. Heavy metal bioconcentration (BCF) was calculated to assess heavy metals bioaccumulation in the aquatic plants.

Polyhydroxyalkanoates (PHAs) have gained much attention as biodegradable polymers, many efforts are being made to minimize the cost of PHAs by finding cheap carbon source depending on the type of microorganism and fermentation conditions. The aims of this study were to evaluate the effects of different glucose concentrations and other important conditions on the PHA production by Bacillus cereus isolated from soil. Polyhydroxyalkanoates PHAs accumulated by soil microorganisms were examined by screening the isolated bacteria using Sudan B Black and Nile Blue staining process. A Gram positive strain was identified using the 16s rRNA gene, deposited in the NCBI GenBank sequence database. Different growth conditions (favorite glucose concentrations 1-8 % (w/v), temperatures and pH) were tested and the growth parameters (sugar consumption, cell counting and Cell Dry Weight CDW) were studied. The extracted polymers were analyzed and characterized using an FTIR spectrophotometer followed by a GC-MS analysis. The pure bacterial strain isolated from soil was deposited in the NCBI GenBank database B. cereus strain ARY73, which showed significant black colored granules (or dark blue) using Sudan B Black stain, it also showed positive to Nile blue A as a high indicator stain for PHA accumulation. B. cereus ARY73 showed high production of PHA using (w/v): 2% glucose and 1% nitrogen source at 35 °C and pH7 yields 79% per Cell Dry Weight and 96 h of incubation. The extracted polymers were analyzed and characterized using an FTIR spectrophotometer confirming the PHA structure. The FTIR spectrophotometer, followed by a GC-MS analysis indicated the Scl-co-mcl PHA structure. This research demonstrates that the isolated strain B. cereus ARY73 was a good candidate for PHA production with a better quality for use in biomedical and other applications. The use of biopolymer in soil, enhanced the accumulation of the microorganisms (such as bacteria) capable of degrading biopolymer or biodegradation by-products yields by other species which were isolated in this study and demonstrated their efficiency in producing biopolymers.

Aquatic macrophyte communities and environmental factors were studied at four Al-Hawizeh marsh sites from December 2017 until November 2018. Quantitative data from thirty species of aquatic plants were collected to investigate density, vegetation cover, biomass and their relationship to the environmental factors. For emerging plants, relative abundance reached the highest values (36%) than submerged and wet species, while free-floating plants produced the lowest value (17%).Physical and chemical properties have been studied including water temperature ranging from 11.3 ° C in January to 31.4 ° C in August, dissolved oxygen (DO)ranging from 1.88 mg/L in September to 10.5 mg / L in April, pH varied from 7.2 in June to 8.4 in December, electrical conductivity (EC μ.S/cm) differs from 2257 μ.S/cm in November to 6859 μ.S/cm in April. The results identified the highest percentages of vegetation cover reported during the summer, the lowest percentages revealed during the winter for all plant groups. The highest annual vegetation cover rates for submergent species achieved 52.54% by C.demersum, for free-floating plants 66.67% of S. polyrrhiza, for emergent plants 85.5% of P. australis, 41.62% of P. paspaloide for wet plants. Total mean biomass of plant groups showed the highest value of 844.02 (gm dry weight/m2) reported by emerging plants, the lowest value of 47.25 (gm dry weight / m2) by the wet plants. Thus, biomass values were correlated with the vegetation cover values for all plants.

The production of polyhydroxyalkanoates PHAs from biopolymer degrading bacteria was examined in situ by screening isolates using Sudan B Black staining process as potential PHAs detecting, and Nile Blue staining as a proof method detection. Five bacterial strains isolated from biopolymer waste buried in a garden soil were able to produce high rate of PHA. AK1P and AK2P strains demonstrated high productivity of biopolymer by converting 5% (w/v) lactose as the only carbon source to PHA during fermentation. AY2P strain converted 5% (w/v) of glucose with less PHA accumulation. The favorite temperature for those strains to produce a high rate of PHA was at 30° C.

The fish assemblage structure in Al-Huwaizah marsh, southern of Iraq was assessed. Fish samples collected monthly by different fishing means from period December 2017 to November 2018. A total of 28959 individual of fish belonging to 9 families and 19 species were collected, 11 of them of native species and 8 of alienspecies. The numerical dominance index value (D3) of the highest three abundant species comprised 74.26% of the total fish caught, included Planiliza abu (Al-Keshny) 38.2% ; Coptodon zilli (Tilapia red abdomen) 29.41% and Carassius auratus (Prussian carp) 6.65%. The total weight of fish caught 2,190,680 tan, highest weight 312,242kg achieved in July, while lowest weight 41,590 kg found in September. The weight dominance index value (D3) of the highest three species in weight recorded 1,409,973 tan of the total weight of fish caught included C. zilli(Tilapia red abdomen) 659,994 kg , S. triostegus (Jerry fresh water) 495,784 kg and O. aureus (Blue tilapia) 245,195kg.The annual rate value for diversity, richness and evenness indices amounted 1.88, 1.75 and 0.64, respectively. Some of physical and chemical properties were studied such as water temperature which ranged from 11.5°C in January to 31.02°C in August month, dissolved oxygen ranged from 2.24 mg/l in September to 9.9mg/l in February, salinity varied from 1.37‰ in November to 3.76‰ in September and pH which ranged from 7.4 in June to 8.15 in December.Jaccard Similarity Index (Ss%) was used to know the similarity degree between the monthly catch samples. Also associations between distribution of fish species and the environmental variables were quantified by using canonical correspondence analysis (CCA).