In the present study, cadmium and lead concentrations were compared in barnacles, ghost shrimps, polychaetes, bivalves, and sediment from ten different locations along the intertidal zone of the Persian Gulf and the Gulf of Oman. The results revealed significant differences in the heavy metal concentrations between the organisms with barnacles showing, by far, the highest metal concentrations. The bioaccumulation factor of Cd in different animals follows this pattern with barnacles > bivalves > polychaetes > ghost shrimps, while the pattern for Pb was barnacles > polychaetes > bivalves > ghost shrimps. In most of the stations, sediments showed the lowest lead and cadmium concentrations. Therefore, it is concluded that barnacles with Pb concentrations between 0.17 and 2,016.1 μg/g and Cd concentrations ranging from 0.4 to 147.1 μg/g are the best organisms to be employed in monitoring programs designed to assess pollution with bioavailable metals in the Persian Gulf and the Gulf of Oman.

Marine organisms as heavy metal bioindicators in the Persian Gulf and the Gulf of Oman.

The main objectives of article were monitor the metal concentrations of cadmium, lead, copper, zinc, cobalt, and iron, in the feather of shorebirds species, Western Reef Heron (Egretta gularis) and Siberian Gull (Larus heuglini) from Hara Biosphere Reserve of Southern Iran; and identify any relationships between species. Assaying heavy metals by using Shimadzu AA 680 flame atomic absorption spectrophotometer, the results were given as micrograms per gram dry weight. The concentrations of heavy metal were found to follow the order of iron>zinc>copper>lead>cadmium>cobalt for E. gularis and of iron>zinc>lead>copper>cadmium>cobalt for L. heuglini. Also, they showed that the cadmium, copper, and cobalt concentrations were higher in females than in the males, while the lead concentration for E. gularis and L. heuglini was higher in males. The cadmium concentration means they were measured as1.16 and 1.37 μg/g for E. gularis and L. heuglini, respectively, whereas the lead concentration means 7.04 and 5.48 μg/g for E. gularis and L. heuglini, respectively. The concentrations of nonessential trace elements in E. gularis and L. heuglini were generally comparable to values reported in other studies. The average levels of lead we observed in these birds were greater than 5 μg/g dry weight in the feather that is known to be associated with adverse behavioral or reproductive effects. Data analysis showed that there was a positive correlation between copper and zinc (P < 0.01), copper and cobalt (P < 0.05).

Heavy metal contamination in feathers of Western Reef Heron (Egretta gularis) and Siberian gull (Larus heuglini) from Hara biosphere reserve of Southern Iran.

The levels of Cd, Cu, Pb and Zn in surface sediment, soft tissue and shell of the oyster Saccostrea cucullata collected from three locations, in the intertidal zones of Lengeh Port, northern part of Persian Gulf were measured. Results indicated that there were a positive correlation across Zn (r = 0.58, p = 0.025), Cd (r = 0.74, p < 0.01) and Cu (r = 0.80, p < 0.01) levels in the soft tissue of oyster and sediment which supported this fact that the soft tissue of S. cucullata can be considered as biomonitoring agent for Cd, Zn and Cu in the Lengeh Port.

Assessment of cadmium, copper, lead and zinc contamination using oysters (Saccostrea cucullata) as biomonitors on the coast of the Persian Gulf, Iran.

Concentrations of Cd, Cu, Pb and Zn in soft tissue of oyster (Saccostrea cucullata) collected from the Lengeh Port coast, Persian Gulf, Iran: A comparison with the permissible limits for public health

Contaminants may affect ecosystem functioning by reducing the fitness of organisms and these impacts may cascade through ecosystems, particularly if the sensitive organisms are also habitat-forming species. Understanding how sub-lethal effects of toxicants can affect the quality and functions of biogenic habitats is critical if we are to establish effective guidelines for protecting ecosystems. We carried out a global systematic review and meta-analysis critically evaluating contaminant effects on properties of habitat-formers linked to ecosystem functioning. We reviewed a total of 95 publications. However, 40% of publications initially captured by the literature search were identified as having flaws in experimental design and ~11% did not present results in an appropriate way and thus were excluded from the quantitative meta-analysis. We quantitatively reviewed 410 studies from 46 publications, of which 313 (~76%) were on plants and seaweeds, that is macro-algae, saltmarsh plants and seagrasses, 58 (~14%) studied corals and 39 (~10%) looked at toxicant impacts on bivalves, with 70% of those on mussels and the remaining studies on oysters. Response variables analysed were photosynthetic efficiency, amount of chlorophyll a (as a proxy for primary production) and growth of plants, seaweeds and corals as well as leaf area of plants. We also analysed filtration, growth and respiration rates of bivalves. Our meta-analysis found that chemical contaminants have a significant negative impact on most of the analysed functional variables, with the exception of the amount of chlorophyll a. Metals were the most widely harmful type of contaminant, significantly decreasing photosynthetic efficiency of kelps, leaf area of saltmarsh plants, growth of fucoids, corals and saltmarsh plants and the filtration rates of bivalves. Organic contaminants decreased the photosynthetic efficiency of seagrass, but had no significant effects on bivalve filtration. We did not find significant effects of polycyclic aromatic hydrocarbons on any of the analysed functional variables or habitat-forming taxa, but this could be due to the low number of studies available. A meta-regression revealed that relationships between concentrations of metal contaminants and the magnitude of functional responses varied with the type of metal and habitat-former. Increasing concentrations of contaminants significantly increased the negative effects on the photosynthetic efficiency of habitat-formers. There was, however, no apparent relationship between ecologically relevant concentrations of metals and effect sizes of photosynthetic efficiency of corals and seaweeds. A qualitative analysis of all relevant studies found slightly different patterns when compared to our quantitative analysis, emphasising the need for studies to meet critical inclusion criteria for meta-analyses. Our study highlights links between effects of contaminants at lower levels of organisation (i.e. at the biochemical and/or physiological level of individuals) and ecological, large-scale impacts, through effects on habitat-forming species. Contaminants can clearly reduce the functioning of many habitat-forming marine species. We therefore recommend the adoption of routine measures of functional endpoints in monitoring and conservation programs to complement structural measures.

Sublethal effects of contaminants on marine habitat-forming species: a review and meta-analysis.

Effective treatments of industrial waste streams an d toxic spills containing heavy metals related with rapid removal of metal ions at high concentrations. Influences of cl earance and absorption rates on two heavy metals (c opper and cadmium) by saccustrea cucullata originated from mangrove ecosystem in the Northern Persian Gulf were investigated. Specimens were collected from sub-tidal band during neap tide; groups of 15 individual were placed in 1.5 L containers (2-liter volume), which were immersed in the water. After the acclimation time (i.e. the regulation of filtration activity caused by manipulation and any other sources), spec ific clearance and absorption performances were measured during alternation of stagnation and flow positions. Tempe rature, salinity and particle concentrations were m aintained. The clearance rate is affected by the amount of cadmium (from 1.69 to 0.04 ml min/g/h AFDW) and copper (from 2.16 ml to 0.42 ml min/g/h AFDW). Although the clearance rate was significantly reduced, live oysters reduced the amount of cadmium and copper from 150 and 200 µg/l to 118.68 and 133.30 µg/l respectively. Oyster had the differ ent clearance rates toward copper and cadmium when simultaneously introduced. The dead shells also had a good abilit y to reduce the metal condensation. According to the results it can be concluded that Sacostrea cucullata can be used as biofilters with good clearance ability.

A. Danekar

Papers

Biosorption and bioaccumulation of heavy metals by rock oyster Saccostrea cucullata in the Persian Gulf