Some Biological and Pollution Aspects of Pearl Oyster Pinctada radiata in Bahrain

Transcription

1 Some Biological and Pollution Aspects of Pearl Oyster Pinctada radiata in Bahrain Hashim Al-Sayed Dept.of Biology,College of Science University of Bahrain,P.O.Box Kingdom of Bahrain For Symposium on Marine Environment & Sustainable Development University of Qatar December 2010 ١

2 Contents Introduction Importance of Oyster Types of Oysters Distribution Shell Morphometry Objectives Periodicity of Spawning Spat Settlement Growth Nutritional Value Microbial Contents Heavy Metal Levels Hydrocarbon Levels ٢

3 Introduction It t is essential to study biology of pearl oyster Oyster is a renewable resources Intensive research is needed Few marine ecologists Most of previous studies conc.on cultural and social aspects Few scientific researches on pearl oyster The following are results of some scientific studies to fill the gap in our knowledge ٣

4 Importance of pearl oyster.bahrain Bahrain renewable resources.fishesfishes.shrimpsshrimps.pear oyster ٤

5 Main source of income Export pearls :three million ( ) Main workforce آتاب لو لو البحرين. المصدر: ٥

6 Natural pearls Protein source Decorations Spat collectors Importance ٦

7 Buttons Necklaces Spat collectors Containers ٧

8 There are seven species in Bhrain P.radiata P.margaritifera Pinctada anamoides P.ingra P.sugillata P.maculata P.margaritifera Most widely P.radiata distributed in oyster beds Density per m.sq. ٨

9 Pinctada radiata Pinctada margaritifera Pinctada macullata Pinctada nigra Pinctada anomioides ٩

10 Favourable environmental conditions High water temp c High salinity 40-49ppt 49ppt Abundant light High calcium conent ١٠

11 Oyster sampling sites ١١

12 Shell morphometry showed spatial variations Ras Hayan: largest sizes( ) Karzakan/Um Nasaan:smallest sizes Saiyeh Island:medium sizes( ) Reasons:food and salinity Electrophorisis ١٢

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14 Oyster beds Off-shore areas:20-30 nautical miles Oyster beds High density: per sq.m. Coastal areas: Askar Jau-Seyah Isl.-Barbar Sparse and scattered distribution ١٤

15 Major oyster beds ١٥

16 Oyster environment Benthic sessile animal Sits on its hinge Opening its valves for water and food ١٦

17 Fouling organisms : Padina Antipatharian Boring sponges Colonial acidian ١٧

18 Fouling organisms affect Growth Rate of pearl formation ١٨

19 Feeding Filter the water and retain Bacteria -Plankton ١٩

20 Nutritional value Oyster flesh contains: Source of protein) % 21% Little lipids( ) Ash contents( ) ٢٠

21 Proximate Composition (Mean ± S.E. and Range) of P. radiata at different Sit Site Protein Percentage Fat Percentage Moisture Percentage Ash Percentage Number of Individuals Al Shaikh Island ±2.9 ( ) 1.03 ±0.2 ( ) ±2.04 ( ) 2.74 ±0.21 ( ) 23 Holiday Inn ±3.35 ( ) 0.82 ±0.27 ( ) ±2.25 (79 85) 3.00 ±0.27 ( ) 26 Jumailat 13.6 ±2.53 (9.2 17) 0.73 ±0.29 ( ) ±2.46 ( ) 2.67 ±0.13 ( ) 20 Bal y aal ±1.49 ( ) 0.96 ±0.11 ( ) ±1.89 ( ) 2.66 ±0.21 ( ) 22 Karzakan ±4.5 (9.4 21) 1.11 ±0.25 ( ) ±1.39 ( ) 3.12 ±0.31 ( ) 21 ٢١

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23 GROWTH OF THE OYSTER Methods of studying growth: Counting growth rings Longitudinal sections Regular measurments of shell length ٢٣

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25 Some important results Rapid growth in first two months after settlement 1.42mm in 7 days 3.40mm in 16 days 9.43mm in 38 days 57.96mm in one year Higher than Japan ٢٥

26 Periodicity of spawning Methods of studying spawning Gonad thin sections Planktonic larvae Gamete counting Water contents Biochemical changes ٢٦

27 Some important results Sampling site: Ras Hayan June-Sept.: peak spawning Oyster does not release gametes at once Gonad maturation Gonad always contains oocytes Critical spawning Temp.: ٢٧

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29 External fertilization Sex indistiguishable Gonad microscopic examination Zygot grows into D-D shaped larvae Unique oyster larvae shape ٢٩

30 Spat settlement Larvae metamorphoses into benthic plantigrade Attached to hard substrate by byssal threads ٣٠

31 For studying spat settlement different collectors used Empty oyster shells Date palm twigs ٣١

32 Nylon ropes Oyster cages Wooden frames To know suitability of such surfaces ٣٢

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34 Sites used for laying spat collectors ٣٤

35 Important results Larval settlement occurred on different substrates Empty oyster shells:highest settlement rate(80spats/shell June-Nov.89:spat settlement time August 89:highest settlement rate which coincide with spawning ٣٥

36 200 collectors:one million oyster spats Fassht Al-Jarim :best site for spat collection Larval stage +settlement time =shorter than other places ٣٦

37 Data obtained from growth experiment of pearl Oyster maintained in cages at Fasht Al-Jarim from September 1989 to March Sampling dates No. of Individuals Mean shell size (mm) Standard error (± S.E.) Mean growth* per 30 days (mm) Mean* water temp. ( º C) 03/09/ /09/ /10/ /10/ /10/ /11/ /12/ /12/ /01/ /02/ /03/ /04/ /05/ /08/ /10/ /11/ /12/ /01/ /02/ /03/ ٣٧

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40 Pollutants Oyster is affected by pollutants Microbial Chemicals Hydrocarbons ٤٠

41 Important results High faecal coliforms WHO limits:10 bacterial/g Oyster should boiled before eaten ٤١

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43 Traces metals Oyster is main indicator for chemical pollution Cupper,Iron,Zinc,Lead,Manganese, Nickel and Cadmium Lead & Cadmium were higher in offshore station than coastal ٤٣

44 Iron,Nickel,Zinc:Higher, in coatal station Cupper&Manganese: : No differences between stations All trace metals were higher in summer than winter Lead and Cadmium :Higher than WHO standards ٤٤

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48 Hydrocarbons Indicator for oil pollution Chlorinated hydrocarbons less than detection limit DDT little more than detection limit Total PCB : ppm ٤٨

49 Conclusion & Recommendations Oyster beds still support large stocks Oyster is an important renewable biological resources Encourage and support oyster research More marine scientists ٤٩

50 Recommendations Research into good quality of Bahraini pearls Research into genetical characterstics of oyster Establish oyster research laboratory ٥٠

51 Thank you for your attention ٥١