Cd, Pb and Zn in Arctica islandica L. (Mollusca: Bivalvia) from Kiel Bay, Western Baltic Sea. Mar. Pollut. Bull.,. 32(9): 631â635. Swaileh, K. M. and Adelung, ...
Seasonal Variations In Biochemical Composition Of The Two Edible Bivalves, Donax Trunculus And Donax Semistriatus A. M. El-Wakf, M. M. El-Naggar, A. N. Guirguis and S. R. Abd El-Ghany Zoology Department, Faculty of science, Mansoura University, Egypt. Abstract The present work deals with studying seasonal variations in the biochemical composition (glycogen content, total proteins and lipids) and other biochemical markers of the two edible bivalves, Donax semistriatus (from polluted locality at Port Said) and Donax trunculus (from clean locality at Gamasa) during period of one year, from June 2003 to May 2004. The changes were assessed in relation to the reproductive activity of the two bivalves and the level of locality heavy metal pollution. Obtained data indicated seasonal variations in the levels of biochemical markers (glycogen content, total proteins and lipids), the antioxidant components (glutathione and glutathione-S-transferase), as well as in the concentrations of heavy metals (Fe, Zn, Pb and Cu) in the bivalves soft tissues, with the highest changes being recorded during summer (period of active reproduction) and the lowest values during winter (period of inactive reproduction). On comparing the two studied bivalves, Donax semistriatus from polluted water tended to exhibit lowered values of glycogen content, total proteins and lipids. Increased antioxidants levels with higher heavy metals accumulation were observed in the bivalve soft tissue during the whole study period. This indicated increased capacity of heavy metals bioaccumulation and thus human consumption of bivalve molluscs from water localities exposed to heavy metals pollution is not advisable. Key words: Bivalve molluscs, Donax, biochemical composition, heavy metals. 1
Aim of the work The soft edible parts of the bivalve molluscs represent an important source of animal protein for people inhabiting coastal areas in Egypt. The shells of these bivalves are also used by some people to manufacture beautiful gifts or to decorate the furniture. In spite of bivalves economic importance and their abundance in Egypt (Aleem, 1969), little attention has been made to study biochemical composition and other biochemical aspects of these animals. Earlier research in this field indicated that bivalves tissue composition varies among different species and among populations of the same
species,
depending
upon
their
physiological
condition
(Thippeswamy and Joseph, 1988 and Honkoop, 2003) and environmental factors, such as seasonality and aquatic pollution status (Guacira and Thomé, 2004 and Lomovasky et al., 2004). The present work, therefore, was carried out to study seasonal variations in biochemical composition and antioxidant components (glutathione and glutathione-S-transferase) in two bivalve species, Donax trunculus and Donax semistriatus, that have economic importance, since they are extensively consumed as sea food. Donax individuals were collected from two sites (polluted and clean) at the Egyptian coast of Mediterranean Sea through period of one year from June 2003 to May 2004. Seasonal fluctuations in the concentrations of heavy metals (Fe, Zn, Pb and Cu) in the two bivalves tissues were also assessed along the study year. This work aimed also to describe differences in the biochemical composition between the two studied bivalve species and the relation between these differences and the level of metals accumulation in the bivalves tissues. 2
Materials and methods Study area: Specimens
of the
bivalves
Donax
trunculus
and
Donax
semistriatus were collected from two localities at the Egyptian coast of Mediterranean Sea (each having one of the two bivalves at abundant number). Samples of D. trunculus were collected from the western side of Gamasa city (31° 30` N and 31° 45` E) at an area covering three kilometers length that considered as clean reference site (not urbanized place). Meanwhile, specimens of D. semistriatus were collected from the eastern side of Port Said city (31° 15` N and 32° 30` E) at an area covering three kilometers length that considered as polluted site (clearly exposed to anthropogenic impact). Water and sediment samples were also collected from the two study areas for heavy metals analysis. Biochemical Methods: Samples of 15 animals of each of the two studied bivalve species were collected seasonally over one year from June 2003 to May 2004. For both Donax species, individuals of intermediate size (fully mature) were selected for biochemical analysis. Following collection, the bivalves were left in filtered sea water overnight to allow any sediment to be cleared from the mantle cavity and the gut. The intact bivalves were
3
washed and left for a short time in air to allow the shell surface to dry before being studied. Animals were then divided into 3 subgroups and the whole soft tissues of the separate individuals in each group were removed for further analysis. Tissues from the 1st subgroup were weighed, homogenized and prepared for estimating tissue levels of total RNA, total DNA and total lipid content, based on the methods of Dishe and Schowrtz (1937); Mejbaum (1939) and Zollner and Kirsch (1962), respectively. Moreover, total glutathione (GSH) content and total glutathione-S-transferase (GST) activity were determined following the methods of Prins and Loose (1969) and Habig et al.(1974), respectively, while total protein content was measured using kits from Diamond Company for Laboratory Services-Egypt, according to Henry (1964). Meanwhile, tissues from the 2nd animals group were immersed in weighed pencilline tubes containing 2 ml of 5% TCA, then prepared for determination of glycogen content as described by Nicolas et al. (1956). The concentrations of heavy metals (Fe, Zn, Pb and Cu) were determined in the soft tissues of the 3rd bivalves subgroup, as well as in the collected samples of water and sediment. Bivalves tissues were dried and digested by concentrated nitric acid for metal analysis. The collected water samples were filtered before analysis and the sediment samples were dried, then prepared for analysis. The values of tested metals were measured in prepared samples of water, sediment and tissue using the atomic absorption spectrophotometer (Perkin Elmer, model 3110).
4
Statistical analysis: Analysis for obtained results was carried out with the aid of the SPSS computer software programme. Data for biochemical variables were expressed as mean ± S.E. To evaluate seasonal variations in biochemical composition for each of the two Donax species throughout a study year, analysis of variance (One-way ANOVA test, P < 0.05) was performed. The differences in body composition between the two studied Donax were also evaluated by comparing data from the two Donax species, using (Student t-test, P < 0.05), where Donax trunculus collected from Gamasa clean locality (relatively clean place) was considered as reference (control) animal. Results In this study, the influences of seasonality and site pollution on the biochemical composition and other biochemical parameters were examined in the two bivalve species, D. trunculus and D. semistriatus during the period from June 2003 to May 2004. Present data showed significant variations between seasons of the study year in biochemical composition indices (protein, lipid, glycogen, DNA and RNA) of the two bivalve species (ANOVA test, P < 0.05), with the highest values being recorded during summer and the lowest during winter. On comparing the two studied bivalves, D. semistriatus from metal polluted environment showed lowered values of body composition 5
indices (t-test, P < 0.05), that seemed significant for all tested parameters during summer, except for total protein, which showed considerable but non significant variations along the whole study period (Table I). Meanwhile, the results recorded for the antioxidant components (GSH and GST) in the two bivalve species showed significant variations between seasons at the study year (ANOVA test, P < 0.05), with the highest variations were noticed during summer and the lowest during winter. In addition, D. semistriatus collected from polluted site exhibited increased antioxidant values if compared to D. trunculus (Table II), that appeared significant for the two antioxidant components, through all the study period, except for GSH that showed non significant variations during spring only (t-test, P < 0.05). As shown in table III, the mean concentrations of all tested metals (Fe, Zn, Pb and Cu) in water samples collected from the two study localities were approximately the same, with exception for Fe that showed higher concentration than other metals through the whole study year. Moreover, the concentrations of the heavy metals in sediment is higher than their concentrations in water, as sediment acts as a reservoir for all the pollutants and dead organic matter descending from the above ecosystem. Also, the highest concentration of all tested metals in sediment was recorded for Fe and the lowest for Cu during the entire period of study. At the same time, the order of the tested metals concentrations in the Donax soft tissues showed similar pattern for those recorded in sediment, with the highest concentration was noticed for Fe and the lowest for Cu. 6
On comparing heavy metals concentrations in water, sediment and soft tissues of bivalves collected from the two study localities, all samples from polluted Port Said locality showed higher metal concentrations during the whole study period. The differences for the tested metals (Fe, Zn and Pb) in the bivalves soft tissues were significant for most of the study period (t-test, P < 0.05), whereas, Cu showed no significant variations for all the study period. Discussion Earlier studies on biochemical composition of bivalve molluscs defined certain characteristic features that considered of importance in understanding the economic importance of bivalves as food for human. They are: (1) protein represents major organic constituent of bivalves body, compared to the other components, lipids and glycogen (Marcano et al., 2003). (2) Bivalve molluscs lack the specific organs for nutrient storage of higher vertebrates and thus body constituents of bivalves represent energy reserves that are changed seasonally, showing cyclic synthesis and utilization (Guacira and Thomé, 2004 and Lomovasky et al., 2004). These findings are in agreement with data from the present study where total protein being the major body component of the two bivalves tissues throughout the whole examination period. Present data also indicated that body composition indices (protein, lipid, glycogen, DNA and RNA) showed seasonal variations through the study period with the highest values of all tested parameters were recorded during summer and the lowest during winter. This indicated that bivalves body constituents build up during summer and showed no reduction until winter where the animals began to draw up their reserves. 7
The explanation is that bivalves body composition may change in response to seasonal changes in environmental conditions, specially in the food availability, where abundance of food during summer allow nutrient storage and use of energy for growth of somatic tissue and also for gonadal development (Manduzio et al., 2004 and Borković et al., 2005). On the other hand, food storage during winter may to some extent be responsible for the decreased body reserves and reproductive capacity of the bivalves (Lomovasky et al., 2004). In support to this, the two bivalve species examined in the present study exhibited annual reproductive changes (non published work) that correlate closely with the cyclic changes in the body reserves, where gonad maturation and gamete production occured during summer, the period in which body reserves are stored, followed by reduced breeding activity during winter, where food reserves seemed to be drawn up to ensure animal survival during the period of inadequate food supply. The present data, on the other hand, identified other differences on comparing the two studied bivalves, where D. semistriatus from metal polluted environment showed lowered body composition indices (protein, lipid, glycogen, DNA and RNA), indicating enhanced breakdown and/or decreased synthesis (Porte et al., 2001) of bivalves body reserves in response to heavy metal exposure. The antioxidant components (GSH and GST): In the bivalve molluscs, a range of antioxidant defence mechanisms are present, including low molecular weight compounds, such as reduced glutathione (GSH) and specially adapted enzymes (Winston, 1991). Among these enzymes, the glutathione-S-transferase (GST) which catalyses conjugation reactions with GSH and is expected to
8
respond to changes in pollution status of marine water (Hayes and Pulford, 1995). In the present study, the influence of site-pollution status and seasonality on the antioxidant components (GSH and GST) was examined in the two bivalves D. trunculus and D. semistriatus. In this study, a marked difference between seasons was observed for the measured antioxidants, with very low value in winter, but elevations in the same parameters were recorded during the rest of the year, particularly during summer. These data together with previous studies (Auffret, 1988; Hietanen et al., 1988; Cossu et al., 2000) showed a correlation between the antioxidant component and seasonality. The explanation is that temperature and food availability in summer induce oxygen consumption and celluar oxygen radicals generation, which are compensated by increasing antioxidant defences (Manduzio et al., 2004 and Borković et al., 2005). Thus, the decrease in the antioxidant components during winter could indicate enhanced susceptibility of bivalves to oxidative stress in this period (Manduzio et al., 2004 and Borković et al., 2005). The other factor to be studied concerning the antioxidant defence system is the level of aquatic metal pollution, as evidenced in the present study by the increased antioxidants (GSH and GST) in D. semistriatus collected from Port Said (polluted locality) as compared to D. trunculus from the clean Gamasa locality. These findings are in agreement with Alcutt and Pinto (1994), who reported an increased GSH level in the hard clam Mercenaria mercenaria following continued acute exposure to lead. 9
Similarly, Rodriguez-Ariza et al. (2003), showed increased GSH level in the oysters, Crassostrea virginica after exposure to cadmium toxicity. Moreover, Le Pennec and Le Pennec (2003) demonstrated the capability of the bivalve Pecten maximus to stimulate GST activity in response to pollution exposure in order to prevent damage to cells and the organism. Heavy metals bioaccumulation in the soft tissues of the bivalves D. trunculus and D. semistriatus: The pollution level of the aquatic environment by heavy metals can be estimated by analyzing water, sediment and marine organisms. The levels of heavy metals in molluscs and other invertebrates are often considerably higher than in other constituents of marine environment (Hamed and Emara, 2006) indicating heavy metals bioaccumulation capacity of bivalves (Ferner, 2001 and Usero et al., 2005). In this regard, it has reported that the extent of metal bioaccumulation in bivalve tissues could be influenced by various environmental factors, such as seasonal variations (Sawailleh and Adelung, 1994 and Sawaileh, 1996). This latter finding can be clearly demonstrated through the present study in such a way that the level of the quantified metals (Fe, Cu, Pb and Zn) in the whole soft tissues of the tested bivalves (D. trunculus and D. semistriatus) tended to vary from season to another, where the maximal values were recorded during summer and the minimal ones were registered during winter. In the present study, these seasonal variations in the quantified metals in the bivalves tissues is not likely to result from changes in the quantity of metals reaching the bivalves environment, as the metals variations in the 10
surface water and sediment generally showed no seasonal pattern. Therefore, this is mostly related to the fact that the increased tissue metal concentrations during summer coincided closely with the period of maximum phytoplankton abundance (Labib and Ibrahim, 1994). Thus, availability of food may be regarded as a major factor determining such seasonal variations. Rather than these seasonal effects, the present study revealed that the concentrations of the quantified metals (Fe, Cu, Pb and Zn) in the whole tissues of the tested bivalve D. semistriatus collected from Port Said (polluted site) were higher than those collected from the less polluted Gamasa locality, indicating increased accumulation of these metals in the bivalve tissues (Smolders et al., 2004 and Negri et al., 2006). This is mostly related to the fact that Port Said locality exposed to higher metal (Fe, Cu, Pb and Zn) concentrations than Gamasa locality as a result of the discharged pollutants, particularly heavy metals coming mainly from oil spillage of ships waiting transit at this locality (Hamed and Emara, 2006). The same explanation was established by other investigators who indicated that bioaccumulation of heavy metals in the bivalve tissues was directly related to their concentration in the aquatic environment in which such molluscs are living (Hamed and Emara, 2006 and Mendez et al., 2006). Other field studies seemed to support the above results and further indicated that metals accumulation in the bivalve tissues is changeable in their order according to the metals levels in their environment (Bacon et al., 1998 and Bayne and Svensson, 2006). This is also indicated by the 11
present data that the four quantified metals in each of the two studied Donax did not exhibit uniform pattern of accumulation, as the Fe showed the highest concentration and Cu the lowest one. This order goes in parallel with the metals concentrations in the surrounding environment (with particular sediment). In this regard, Bayne and Svensson (2006) reported that bivalves accumulate metals in proportion to their availabilities, in the water and sediment, since, Donax species are sessile and filter feeders and thus obtain heavy metals not only from food and water, but also from sediment (Gaspar et al., 2002). Conclusion Obtained data indicated that body composition (protein, lipid and glycogen) in the two studied Donax species tended to change from season to season, with the highest values were recorded during summer and the lowest during winter. Differences were also observed between the two studied bivalves, where D. semistriatus from metal polluted environment exhibited lower body components with increased metals accumulation that seemed to be related to the increased metal concentrations in the ambient environment. Therefore, season and environmental pollution status can be considered as major factors determining quality of bivalve molluscs consumed by human as sea food. References Alcutt, F. and Pinto, J. T. (1994). Glutathione concentrations in the hard clam, Mercenaria mercenaria, following laboratory exposure to lead (a potential model system for evaluating exposure to
12
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Dische, Z. and Schowrtz, K. (1937). Cited in Mikrochim. Acta., 2: 13. Quoted from Abd El-Salam, I. M., Ph. D. Thesis, Faculty of Science, Ain Shams University, Egypt. Ferner, D. J. (2001). Toxicity, heavy metals. eMed. J., 25; 2(5): 1. Gaspar, M. B.; Santos, M. N.; Paulo Vasconcelos Carlos, C. And Monteiro, C. C. (2002). Shell morphometric relationships of the most common bivalve species (Mollusca: Bivalvia) of the Algarve coast (southern Portugal). Hydrobiol., 477: 73–80. Guacira, M. G. and Thomé, J. W. (2004). Descrição do ciclo reprodutivo de Donax hanleyanus (Bivalvia, Donacidae) no sul do Brasil. Iheringia, Sér. Zool., Porto Alegre, 94(3):271-276. Habig, W. H.; Pabst, M. J. And Jakoby, W. B. (1974). Glutathione-Stransferases. J. Biol. Chem., 249: 7130-7139. Hamed, M. A. and Emara, A. M. (2006). Marine molluscs as biomonitors for heavy metal levels in the Gulf of Suez, Red Sea. J. Mar. Syst., 60(3-4): 220-234. Hayes, J. D. and Pulford, D. J. (1995). The glutathione-S-transferase supergene family: regulation of GST and the contribution of the isoenzymes to cancer chemoprotection and drug resistance. CRC Crit. Rev. Biochem. Mol. Biol., 30: 445–600. Henry, R. J. (1964). Clinical Chemistry, Harper and Row Publishers, New York, 1964. p.181. Hietanen, B.; Sunila, I. and Kristoffersson, R. (1988). Toxic effects of zinc on the common mussel Mytilus edulis L. (Bivalvia) in brackish water. I. Physiological and histopathological studies. Ann. Zool. Fenn., 25: 341-347.
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Honkoop, P. J. C. (2003). Physiological costs of reproduction in the Sydney rock oyster Saccostrea glomerata: How expensive is reproduction? Oecologia, 135: 176-183. Labib, W. and Ibrahim, A. (1994). Dynamic of phytoplankton crop along the Mediterranean near-shore water of Port-Said (Egypt). Int. Conf. Fut. Aquat. Res. In Arab Region., 336–350. Le Pennec, G. and Le Pennec, M. (2003). Induction of glutathione-Stransferases in primary cultured digestive gland acini from the mollusk bivalve Pecten maximus (L.): application of a new cellular model in biomonitoring studies. Aquat. Toxicol., 64: 131-142. Lomovasky, B. J.; Morriconi, E.; Brey, T. and Calvo, J. (2004). Individual age and connective tissue lipofuscin in the hard clam Eurhomalea exalbida. J. Exp. Mar. Biol. Ecol., 276: 83-94. Manduzio, H., Monsinjon, T., Galap, C., Leboulenger, F., Rocher, B. (2004). Seasonal variations in antioxidant defences in blue mussels Mytilus edulis collected from a polluted area: major contributions in gills of an inducible isoform of Cu/Znsuperoxide dismutase and of glutathione-S-transferase. Aquat. Toxicol., 70: 83– 93. Marcano, J. S.; Prieto, A.; Lárez, A. And Salazar, H. (2003). Crecimiento de Donax denticulatus (Linné 1758) (Bivalvía: Donacidae) en la ensenada La Guardia, isla de Margarita, Venezuela. Zootec. Trop., 21(3): 237-259. Mejbaum, W. (1939). Uber die bestimmung Kleiner pentosemngen insbesondere in derivaten der adenylsaure. Z. Physiol. Chem., 258: 117.
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Mendez, L.; Palacios, E.; Acosta, B; Monsalvo-Spencer, P. and Alvarez-Castaneda, T. (2006). Heavy metals in the clam Megapitaria squalida collected from wild and phosphorite mine-impacted sites in Baja California, Mexico: considerations for human health effects. Biol. Trace Elem. Res., 110(3): 275287. Negri, A.; Burns, K.; Boyle, S.; Brinkman, D. and Webster, N. (2006). Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica. Environ. Pollut., 143(3): 456467. Nicolas, V. Cara; Robert, W. Longley and Joseph, H. Roe. (1956). The determination of glycogen in liver and muscle by use of anthrone reagent. J. Biol. Chem., 220(2): 583-593. Porte, C.; Biosca, X.; Sole, M. and Albaiges, J. (2001). The integrated use of chemical analysis, cytochrome P450 and stress proteins in mussels to assess pollution along the Galician coast (NW Spain). Environ. Pollut., 112(2): 261-268. Prins, H. K. and Loose, J. A. (1969). Glutathione. Chapter-4. Biochemical Methods In Red Cell Genetics. Edited Academic Press. N. Y. D. London, 126-129pp. Rodriguez-Ariza, A.; Rodriguez-Ortega, M. J.; Marenco, J. L.; Amezcua, O.; Alhama. J. and Lopez-Barea, J. (2003). Uptake and clearance of PCB congeners in Chamaelea gallina: response of oxidative stress biomarkers. Comp. Biochem.
Physiol. C: Toxicol. Pharmacol., 134(1): 57-67. Smolders, R.; Bervoets, L. And Blust, R. (2004). In situ and laboratory bioassays to evaluate the impact of effluent discharges on receiving aquatic ecosystems. Environ. Poll., 132(2): 231-243. 16
Swaileh, K. M. (1996). Seasonal variations in the concentrations of Cu, Cd, Pb and Zn in Arctica islandica L. (Mollusca: Bivalvia) from Kiel Bay, Western Baltic Sea. Mar. Pollut. Bull., 32(9): 631–635. Swaileh, K. M. and Adelung, D. (1994). Levels of trace metals and effect of body size on metal content and concentration in Arctica islandica L. (Mollusca: Bivalvea) from Kiel Bay, Western Baltic. Mar. Pollut. Bull., 28(8): 500-505. Thippeswamy, S. and Joseph, M. M. (1988). Seasonal variability in the condition of the wedge clam, Donax incarnates (Gmelin). In: M. Mohan Joseph (Ed). The First Indian
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Mangalore. 247-249pp. Usero, J.; Morillo , J. and Gracia, I. (2005). Heavy metal concentrations in molluscs from the Atlantic coast of southern Spain. Chemosphere, 59: 1175–1181. Winston, G. W. (1991). Oxidants and antioxidants in aquatic animals. Comp. Biochem. Physiol. C, 100 (1–2): 173–176. Zollner, N. and Kirsch, K. (1962). Colorimetric method for determination of total lipids. Z. Ges. Exp. Med., 135: 545-550.
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Table (I). Changes in body composition (proteins, lipids and glycogen) and nucleic acids (DNA and RNA) of the soft tissues of the bivalves Donax trunculus and Donax semistriatus collected from less polluted and polluted areas during the period from June 2003 to May 2004. Donax trunculus Season
Donax semistriatus
Total proteins
Total lipids
a
73.73 ± 6.95
86.31 ± 11.15
a
48.67 ± 5.43
39.70 ± 5.48
a
a
Glycogen
DNA a
RNA a
Total proteins
Total lipids
139.83 ± 6.18
b
60.79 ± 3.69
bc
60.01 ± 12.21
bc
44.80 ± 5.90
Glycogen
DNA bc
RNA bc
Summer
143.74 ± 6.32
Autumn
102.30 ± 17.06
51.70a ± 1.96
58.85 ± 17.20
a
25.73 ± 4.10
a
23.75a ± 1.95
83.84 ± 18.40
b
49.25 ± 6.38
b
56.05 ± 16.24
b
21.86 ± 0.98
bc
21.55b ± 1.95
Winter
51.89a ± 5.99
39.99a ± 4.53
18.95a ± 2.69
22.00a ± 0.72
19.53a ± 4.48
51.05b ± 6.26
38.29b ± 3.60
18.10b ± 2.52
21.47b ± 0.69
17.83b ± 3.22
Spring
96.02a ± 15.13
59.30a ± 5.93
45.96a ± 11.21
36.33a ± 3.30
33.16 ± 1.32
a
93.80b ± 15.78
47.64bc ± 2.72
23.67b ± 1.77
34.73b ± 2.73
31.68 ± 0.88
Data are mean ± S.E. of 15 samples of each Donax per season. a Significantly different from other periods of collection for D. trunculus (One-way ANOVA test, P < 0.05). b Significantly different from other periods of collection for D. semistriatus (One-way ANOVA test, P < 0.05). c Significantly different compared to the other Donax species (D. trunculus) at the respective date of collection (t-test, P < 0.05).
18
32.63 ± 4.61
b
Table (II). Changes in antioxidant components (GSH and GST) of the soft tissues of the bivalves Donax trunculus and Donax semistriatus collected from less polluted and polluted areas during the period from June 2003 to May 2004. Donax trunculus
Donax semistriatus
Season GSH
GST
GSH
GST
Summer
7.16 ± 0.90
a
8.65a ± 0.15
8.68 ±0.44
bc
9.69bc ±0.33
Autumn
6.74 ± 0.58
a
7.36a ± 0.26
8.50 ± 0.33
bc
8.78bc ± 1.07
Winter
4.75 ± 0.34
a
4.50a ± 0.17
5.76 ± 0.68
bc
5.44bc ± 0.49
Spring
5.62 ± 0.16
a
6.29a ± 0.11
6.77 ± 0.44
b
7.46bc ± 0.62
Data are mean ± S.E. of 15 samples of each Donax per season. a Significantly different from other periods of collection for D. trunculus (One-way ANOVA test, P < 0.05). b Significantly different from other periods of collection for D. semistriatus (One-way ANOVA test, P < 0.05). c Significantly different compared to the other Donax species (D. trunculus) at the respective date of collection (t-test, P < 0.05).
19
Table (III). Changes in heavy metals concentrations in water, sediment and soft tissues of the bivalves Donax trunculus and Donax semistriatus collected from less polluted and polluted areas during the period from June 2003 to May 2004. Season
Material Water
Summer
Sediment Tissues Water
Autumn
Sediment Tissues Water
Winter
Sediment Tissues Water
Spring
Sediment Tissues
Fe 0.060 ± 0.005 0.847 ± 0.210 1.990 ± 0.440 0.053 ± 0.006 0.750 ± 0.180 1.500 ± 0.190 0.053 ± 0.003 0.653 ± 0.063 1.480 ± 0.080 0.053 ± 0.003 0.893 ± 0.049 1.520 ± 0.180
Gamasa locality Zn Pb 0.043 ± 0.003 0.513 ± 0.020 1.460 ± 0.160 0.033 ± 0.007 0.490 ± 0.031 1.160 ± 0.050 0.023 ± 0.003 0.537 ± 0.038 1.060 ± 0.050 0.040 ± 0.006 0.540 ± 0.023 1.340 ± 0.180
a
0.040 ± 0.006 0.427 ± 0.015 0.440a ± 0.020 0.041a ± 0.006 0.483 ± 0.007 0.320a ± 0.010 0.033a ± 0.003 0.513 ± 0.009 0.130a ±0.010 0.037a ± 0.007 0.470 ± 0.038 0.300a ± 0.020
Cu
Fe
0.033 ± 0.003 0.083 ± 0.003 0.120 ± 0.020 0.037 ± 0.003 0.083 ± 0.009 0.080 ± 0.010 0.023 ± 0.003 0.070 ± 0.006 0.060 ± 0.010 0.033 ± 0.003 0.070 ± 0.010 0.100 ± 0.010
0.070 ± 0.005 1.600 ± 0.205 5.250bc ± 1.040 0.067 ± 0.003 1.573 ± 0.323 2.550bc ± 0.080 0.057 ± 0.003 1.050c ± 0.032 2.250b ± 0.540 0.067c ± 0.009 1.187c ± 0.101 2.730bc ± 0.570
Port Said Locality Zn Pb 0.047 ± 0.003 0.700c ± 0.026 3.060 ± 0.650 0.037 ± 0.003 0.533 ± 0.003 2.270c ± 0.560 0.030 ± 0.001 0.603 ± 0.060 2.050c ± 0.110 0.050 ± 0.006 0.620 ± 0.051 2.610c ± 0.110
0.047 ±0.003 0.473b ± 0.014 0.710bc ± 0.060 0.047 ± 0.003 0.533bc ± 0.003 0.430b ± 0.070 0.047c ±0.009 0.533b ± 0.018 0.300bc ± 0.010 0.053 ±0.003 0.560b ± 0.006 0.670bc ± 0.070
Data are mean ± S.E. of 3 samples of (water, sediment and tissue) per season. a Significantly different from other periods of collection for samples from Gamasa (One-way ANOVA test, P < 0.05). b Significantly different from other periods of collection for samples from Port Said (One-way ANOVA test, P < 0.05). c Significantly different compared to the control samples collected from Gamasa at the respective date of collection (t-test, P < 0.05).
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Cu 0.040b ± 0.001 0.093 ± 0.003 0.150 ± 0.007 0.037b ± 0.003 0.097 ± 0.012 0.110 ± 0.010 0.023b ± 0.003 0.077 ± 0.003 0.080 ± 0.010 0.037b ± 0.003 0.087 ± 0.009 0.120 ± 0.030
التغيرات الموسمية فى التركيب البيوكيميائى لنوعين من المحار الصالح لألكل،
دوناكس ترنكيولس ،دوناكس سيميسترياتس.
عزه محمد الوقف ،محمد محمد النجار ،عادل نجيب جرجس ،شريف رمضان عبدالغنى. قسم علم الحيوان ،كلية العلوم ،جامعة المنصورة ،مصر. الملخص يهت م اتتلا البح ت بدراستتة ال غيتترام الموستتمية رتتى ال ركيتتب البيوكيميتتا ى مح تتوا الن تتا الحيتتوانى ،لالبتترلايك ال لتتى ،لالتتداون ال ليتتةض لكتتللي بعتتي المعتتايير البيوكيميا يتتة ا
تترا رتتى
نوعيك مك المحار الصتال لككت ،دلنتاكس سيميست ريااس متك منقةتة ملو تة بمدينتة بورستعيدض، دلناكس ارن يولس مك منقةة غير ملو ة بمدينة جمصهض رى الل عام لاحتد .لقتد اتم اةيتيم اتله ال غييرام بالنسبة للن اط ال ناسلى للمحار لكللي بالنسبة لمس وا الوث منقة ى الدراسة بالمعتادن الثةيلة. لقد أظهترم الن تا
الم احتة حتدلث اغيترام موستمية رتى مست وا المعتايير البيوكيميا يتة
المةيستتة مح وا الن تتا الحيتتوانى ،لالبتترلايك ال لتتى ،لالتتداون ال ليتتةض لكتتللي المركبتتام المضتتادة لككستتدة الجلواتتا يون ،لالجلواتتا يون ارانستت يريزض لمس ت وا العنالتتر الثةيلتتة الحديتتد ،الزنتتي، الرلاص ،لالنحاسض رى أنسجة المحار الر وة .لكانت اتله ال غيترام أعلتى متا ا تون رتى رصت الصيف ر رة الن اط ال ناسلىض لأق ما ا ون رى رص ال اء ر رة اوقف الن اط ال ناسلىض. لعنتتد مةارنتتة نتتوعا المحتتار مح ت الدراستتة ،أظهتتر دلنتتاكس سيميس ت ريااس متتك الميتتاه الملو ة انخ اضا ً رى مس وا ك مك مح وا الن ا الحيتوانى ،لالبترلايك ال لتى ،لالتداون ال ليتةض لكتللي ارا تتام مست وا مضتادام ا كستدة لزيتتادة اتتراكم العنالتر الثةيلتتة بأنستج ه الر تتوة تتالل ر رة الدراسة .ليدل ذلي على زيتادة مةتدرة دلنتاكس سيميست ريااس علتى اتراكم كميتام أعلتى متك المعادن الثةيلة لللا ينص ب جنب انالل المحار رى المناطق المعرضة لل لوث بالمعادن الثةيلة.
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