اسم المؤلف:
انوار مالك جبار المالكي
المستخلص:
The present study intended to shed the light on some biological aspects of the invasive oriental river Shrimp Macrobrachium nipponense compared with that of Jinga shrimp Metapenaeus affinis . For this purpose, Monthly samples were collected and chosen from four Aquatic sites was chosen in the Basrah province (one at each of Al - Mashab and Al - Sallal Marshes and two at Al - Garmah River) during the period from July 2015 to June 2016. collection was done by Fishnet pulled by a boat .The Shrimp numbers were calculated during the time unit (ind./hour) .The Water’s temperature and salinity were studied, it ranged from 15 - 33 ͦ c and 2 - 9.1psu respectively. From a total of 3326, individuals were collected during the study period, only 7% were belong to the first shrimp (M. nipponense ) Compared with 93% to the second shrimp( M. affinis ).The number of each species studied shrimps, varied the monthly. The high number of M. nipponense was 38(ind./hour) recorded during July 2015 and June 2016, while the lowest was 2 (ind./hour) recorded during October and November 2015 . For M. affinis The number of individuals ranged between 980(ind./hour) during August 2015 and 29 (ind./hour) during November 2015 .The comparative monthly percentages were high during seven and six months in the marshes sites recorded for first and second shrimp respectively. The monthly variation in percentages of the two species of shrimps was studied, It ranged (for M. affinis) from 98.8% during August 2015 to 56.8% during July 2015 , while for M. nipponense , It ranged from 43.2% during July 2015 to 1.2% during August 2015 .The results of Frequency showed that the highest percent (100%) was recorded in four months for M. nipponense , these are July, October 2015 February and May 2016. While M. affinis was recorded in most months.Summary bThe population sizes for the two species were studied. For the first species( M. nipponense ), the size class 50 - 60mm dominant during all months of the study period, While for the second species (M. affinis), the size classes 40 - 50, 50 - 60, 60 - 70, and 70 - 80 were recorded during all the months for the first shrimp, the highest percent was 47.3% recorded for the size class 70 - 80 mm , While there is no individuals recorded for the size class 10 - 20 mm during all the months except July 2015 for the second shrimps ,the percentage ranged between 41.4% and less than 1% recorded during May 2016 to March 2016 respectively. On the other hand , the total Frequency for M. nipponense ranged from 83.3% to 0% for the size classes 70 - 80 mm and 10 - 20 mm respectively, While for M. affinis was from 100% recorded for the classes 40 - 50, 50 - 60, 60 - 70 and 70 - 80mm to 8.3% for the class .The Length - Length and Length - weight relationships for the two species were studied The results showed positive correlation between the total length and each of cephalothorax length and abdomen length (r= 0.932 and r= 0.945 respectively, P≤0.01 ) for M. nipponense , Also M. affinis , the correlation was positive for the total length and each of cephalothorax length(r= 0.938) and abdomen length (r= 0.971) (P≤0.01 ) . The correlation was positive between the total length and wet weight for each M. nipponense (r= 0.918 P≤0.01) and M. affinis (r= 0.913 P≤0.01).The Statistical analysis for the weight - weight relationships showed positive correlation between dry and wet weight for M. nipponense (r= 0.966, P≤0.01) and M. affinis (r= 0.918 P≤0.01).The correlation between the lengths of the body and the 2nd chela for male & female of M. nipponense (r= 0.909 and r= 0.823 respectively), these values of correlation refer to the continuous growth of the 2nd chela in male even after the adult stage .Summary cThe concentrations of ten heavy and light metals in shells & muscles of the two shrimps were studied. The results showed a significant differences in eight of them (Cadmium, Potassium, Calcium, Iron, Magnesium, Nickel, Zinc and Sodium) . While there is no significant differences recorded for Lead and Cobalt .The study of some biological aspect which concerned with distribution of eggs on pleopods of females of M. nipponense , showed that the highest mean of eggs was 547.3 (38%) carried on the 2nd pleopod while there are fewer means carried on 1st and 3rd pleopods , and no carry eggs (0%)were carried on the 5th pleopod. The Statistical analysis showed that there was significant differences between the eggs carried on 4th and 5th pleopods and each of the rest ones . lengths of pleopod was positively correlated with the number of eggs (r= 0.661, P≤0.01) The weight of ovigerous female was positively correlated with weight of eggs (r= 0.835, P≤0.01) .The combined effects of salinity and temperature on survival of newly hatched larvae (zoea1 and zoea2) of M. nipponense for 24 & 48 hours’ were tested.The highest survival percentage (100%) for zoea1 was recorded in 12 psu salinity in each of 18, 22 and 26 ͦ c ,While the lowest survival (0%) was recorded in distal water in each 30 and 34 ͦ c . the highest survival percentage was recorded in 12 psu salinity in each 18, 22, 26 and 30 ͦ c. While the lowest one recorded in distal water and 34 ͦ c. The Statistical analysis showed that the percentage survival correlates negatively with temperature and positively with salinity each alone. the combined effect of salinity and temperature on survival was positive with percentage ranged between 38 - 56 % .
