Effect of heavy metals (Zn,Hg, Cu,Cd, Pb,Ni) on the length growth of Mytilus edulis

The shortterm (10–22 d) effect of Zn, Hg, Cu, Cd, Pb, and Ni on the length growth of Mytilus edulis is studied. Significant reductions of growth rate was found at 0.3 g Hgl^-1, 3 g Cul^-1, 10 g Znl^-1, and 10 g Cdl^-1 added to the local sea water, while concentrations of up to 200 gl^-1 of Pb and Ni had no effect on the growth. With exposure to Cu and Zn, there was a linear reduction in growth rate with increasing metal concentration up to about 6 g Cul^-1 and 100 g Znl^-1. Above these levels, growth stopped with Cu, while with Zn it was stabilized at about 20% of control growth. When Hg and Cd were added, a curvilinear relationship between growth and metal concentration is indicated. With Hg, growth rate is nearly zero above 3–4 g Hgl^-1, while the growth rate was 50% of control after 10 d of exposure to 100 g Cdl^-1. At 2 g Cdl^-1 there was a significant stimulation of length increase. Observed EC₅₀-values for growth were 0.3–0.4 g Hgl^-1, 3–4 g Cul^-1, 60 g Znl^-1, and 100 g Cdl^-1.     

Lead and cadmium in urban allotment and garden soils and vegetables in the United Kingdom

In order to assess the intake of lead and cadmium by consumers of home grown vegetables in urban areas, replicated experimental plots of uniform size, comprising summer and winter crops, were established in 94 gardens and allotments in nine towns and cities in England.The geometric mean lead and cadmium concentrations for the soils (n = 94) were 217 g g^–1 (ranging from 27 to 1,676 g g^–1) and 0.53 g g^–1 (<0.2–5.9 g g^–1), respectively. Compared with agricultural soils, the garden and allotment soils contained elevated levels of lead but not cadmium.Lead concentrations in the vegetables ranged from <0.25 g g^–1 to 16.7 g g^–1 dry weight and cadmium concentrations ranged from <0.025 g g^–1 to 10.4 g g^–1 dry weight. Lead concentrations were higher than reported background levels, although <1% exceeded the statutory limit for saleable food in the UK (1 g g^–1 fresh weight). Cadmium concentrations were generally similar to background levels.     

Effects of light intensity on nitrate and nitrite uptake and excretion by Chaetoceros curvisetus

Michaelis-Menten uptake kinetics were observed at all light intensities. With constant illumination, the V_max and K₁ in nitrate uptake over the natural light intensity range of 0 to 2000 E were 0.343 g-at NO₃–N(g)^-1 at protein-N h^-1 and 26 E, respectively. Nitrate uptake was inhibited at higher light intensities. The K_s for nitrate uptake did not vary as a function of light intensity remaining relatively constant at 0.62 g-at NO₃–N 1^-1. With intermittent illumination, the V_mzx for light intensity in nitrate uptake over a light intensity range of 0 to 5000 E was 0.341 g-at NO₃–N(g)^-1-at protein-N h^-1. No inhibition of nitrate uptake was observed at higher than natural light intensities. Chaetoceros curvisetus will probably never experience light inhibition of nitrate uptake under natural conditions.     

Mytilus edulis planulatus: an “integrator” of cadmium pollution?

Mussels, Mytilus edulis planulatus, were collected from Port Phillip Bay, Victoria, Australia, in February 1984, to test the assumption that they are integrators of cadmium pollution. Groups of mussels were subjected to the same average dose of cadmium (21 g l^-1), administered according to different dosing regimes over 4 wk (Regimes 1, 2, 3, 5); other groups received twice the average dose (42 g l^-1) in half the time (Regime 4). During each regime, the mussels were exposed to the different cadmium concentrations for one week at each concentration. Nominally, the regimes were: (1) 36 g (Wk 1) to 26 g (Wk 2) to 16 g (Wk 3) to 6 g (Wk 4) Cd l^-1; (2) 6 to 16 to 26 to 36 g Cd l^-1; (3) 21 to 21 to 21 to 21 g Cd l^-1; (4) 42 to 42 g Cd l^-1; (5) 42 to 42 g Cd l^-1 to background (<0.5 g) to background. Differences in cadmium accumulation by mussels from Regimes 1 and 4 were not statistically significant, nor were differences in accumulation between mussels from Regimes 2 and 3. However, mussels from Regimes 1 and 4 had accumulated significantly more cadmium than had mussels from Regimes 2 and 3. Accumulation by mussels from Regime 5 was not significantly different from that by mussels from any of the other regimes. These results suggest that, at least for cadmium, the assumption that mussels are integrators of pollution should be treated with caution. They also have implications with regard to the quantitative biological monitoring of pollution. For example, even in a carefully controlled monitoring program, using mussels of standard size and condition, significant differences in cadmium content between mussels need not indicate exposure to different levels of contamination. Rather, these differences could reflect differences in the regime by which the contamination was received.     

Cadmium accumulation,LC50 and oxygen consumption in the tropical marine amphipod Elasmopus rapax

Adult Elasmopus rapax, collected from the eastern coast of Venezuela in 1990, were exposed to seawater containing various CdCl₂ concentrations ranging from 0.25 to 5.5 mol l^-1. The 48-h and 96-h LC₅₀ values obtained were 4.0 and 1.6 mol Cd l^-1, respectively. In amphipods exposed to 1 mol Cd l^-1 for up to 240 h, the apparent rate of cadmium uptake was higher in dead animals (most of which had molted during the preceding 24 to 48 h) than in those which survived throughout the treatments without molting. Thus, whole-body cadmium content reached 1.74 mol g^-1 dry weight (dw) in the former and only 0.85 mol g^-1 dw in the latter; the higher body Cd-load may have caused the increased mortality observed in molters. On exposure to cadmium levels above 0.5 mol l^-1 the oxygen consumption rate of non-molters decreased from 2.2 to about 1.5 ml O₂ g^-1 dw h^-1 over the first 24 h, remaining unchanged thereafter. The results place E. rapax among the most sensitive marine organisms yet studied concerning cadmium toxicity, and emphasize the usefulness of the Amphipoda as bioindicators and research tools for bioassays.     

Seston composition of the bottom waters of Great Lameshur Bay,St. John,US Virgin Islands

Seston composition [particulate organic carbon (POC), particulate nitrogen (PN), phyto- and microzooplankton numbers and biomass] was investigated in the bottom waters of Great Lameshur Bay, St. John, Virgin Islands (USA), in October, 1970 during Tektite II Mission 17–50. Mean values of 67.4 g POC · I^-1 and 7.2 g PN · I^-1 were determined. A mean phytoplankton carbon content of 42.2 g · I^-1 and zooplankton carbon content of 5.5 g · I^-1 were calculated from counts. The phytoplankton consisted mainly of dinoflagellates 71.2% phytoplankton carbon. Copepods were the dominant zooplankters (61.8% zooplankton carbon), followed by larvaceans (30.9% zooplankton carbon). Organic carbon content of counted zooplankton faecal pellets ranged between 0.4 and 1.6 g · I^-1, and amounted probably to about 15% of the total zooplankton carbon value. Plankton and detritus components as possible food for coral-reef animals are discussed. The ratio carbon: nitrogen of suspended particles is compared to that of sedimented matter.     

Physiological ecology of picoplankton in the North Sea

The distribution of cyanobacteria in the surface waters of the North Sea was measured during July 1987. Numbers of cyanobacteria ranged from 2.5x10⁶ to 1.7x10⁸ cells 1^-1. In the majority of stations, cyanobacterial numbers were highest in the near-surface water and a subsurface maximum was found at only one station. The distribution of ¹⁴C among the end-products of photosynthesis was determined for picoplankton (<1 m) and other phytoplankton >1 m throughout the North Sea. The majority of label was found in the protein fraction of both picoplankton and >1 m phytoplankton; incorporation into lipids and polysaccharides plus nucleic acids was much lower. We interpret the large incorporation into protein to be a consequence of nutrient limitation of these natural assemblages. Photosynthetic parameters of the two size fractions were also determined. Assimilation number (P _m ^B ) and initial slope were greater for the picoplankton fraction than for phytoplankton >1 m but there was no evidence of significant photoinhibition of either fraction at irradiances up to 1 000 E m^-2 s^-1.     

Effects of nitrogen and phosphorus enrichement on in vivo symbiotic zooxanthellae of Pocillopora damicornis

The reef coral Pocillopora damicornis (Linnaeus) was grown for 8 wk in four nutrient treatments: control, consisting of ambient, unfiltered Kaneohe Bay seawater [dissolved inorganic nitrogen (DIN, 1.0 M) and dissolved inorganic phosphate (DIP, 0.3 M)]; nitrogen enrichment (15 M DIN as ammonium); phosphorus enrichment (1.2 M DIP as inorganic phosphate); and 15 M DIN+1.2 M DIP. Analyses of zooxanthellae for C, N, P and chlorophyll a after the 8 wk experiment indicated that DIN enrichment increased the cellular chlorophyll a and excess nitrogen fraction of the algae, but did not affect C cell^-1. DIP enrichment decreased both C and P cell^-1, but the decrease was proportionally less for C cell^-1. the response of cellular P to both DIN and DIP enrichment appeared to be in the same direction and could not be explained as a primary effect of external nutrient enrichment. The observed response of cellular P might be a consequence of in situ CO₂ limitation. DIN enrichment could increase the CO₂ (aq) demand by increasing the net production per unit area. DIP enrichment could slow down calcification, thus decreasing the availability of CO₂ (aq) in the coral tissue.Hawaii Institute of Marine Biology Contribution No. 920     

Feeding,growth and bioluminescence of the heterotrophic dinoflagellate Protoperidinium huberi

Feeding, growth and bioluminescence of the thecate heterotrophic dinoflagellate Protoperidinium huberi were measured as a function of food concentration for laboratory cultures grown on the diatom Ditylum brightwellii. Ingestion of food increased with food concentration. Maximum ingestion rates were measured at food concentrations of 600 g C l^-1 and were 0.7 g C individual^-1 h^-1 (1.8 D. brightwelli cells individual^-1 h^-1). Clearance rates decreased asymptotically with increasing food concentration. Maximum clearance rates at low food concentration were ca. 23 l ind^-1 h^-1, which corresponds to a volume-specific clearance rate of 5.9x10⁵ h^-1. Cell size of P huberi was highly variable, with a mean diameter of 42 m, but no clear relationship between cell size and food concentration was evident. Specific growth rates increased with food concentration until maximum growth rates of 0.7 d^-1 were reached at a food concentration of 400 g C l^-1 (1000 cells ml^-1). Food concentrations as low as 10 g C l^-1 of D. brightwellii (25 cells ml^-1) were able to support growth of P. huberi. The bioluminescence of P. huberi varied with its nutritional condition and growth rate. Cells held without food lost their bioluminescence capacity in a matter of days. P. huberi raised at different food concentrations showed increased bioluminescence capacity, up to food concentration that supported maximum growth rates. The bioluminescence of P. huberi varied over a diel cycle, and these rhythmic changes persisted during 48 h of continuous darkness, indicating that the rhythm was under endogenous control.     

Growth and survival of Mytilus edulis larvae exposed to low levels of dibutyltin and tributyltin

Two studies were conducted to observe effects of dibutyltin (DBT) and tributyltin (TBT) on larvae of Mytilus edulis for an exposure period of 25 d. Endpoints for evaluation were shell growth and mortality measured at 33 d. Larvae were cultured in a new laboratory assay chamber in a recirculating static test. The control, 2, 20, and 200 g/l DBT-treated populations had mean shell lengths of 527, 523, 417, and 180 m, respectively. Survival was 1% for the 200 g/l DBT-treated population, but ranged from 73 to 83% for controls, 2, and 20 g/l treatments. The no-observed-effect concentration (NOEC) was 2 g/l for DBT, while the lowest-observed-effect concentration (LOEC) was 20 g/l. The chronic toxicity value was 6.3 g/l. In the TBT bioassay, mean shell lengths for the control, 0.006, 0.050, and 0.130 g/l-treated populations were 565, 437, 385, and 292 m, respectively. Control survival was 74%, whereas TBT-treated populations survival ranged from 52 to 58%. The NOEC for TBT was 0.006 g/l TBT and the LOEC was 0.050. A chronic toxicity value of 0.017 g/l was calculated. The results of this study indicated that the toxicity of DBT was less than that of TBT. It was concluded that shell length was inversely related to exposure level in both DBT and TBT bioassays. In this study, we have observed TBT effects at lower exposure levels in the laboratory than previously reported, and also report the first data for DBT effects on mussel larvae.     

Background levels of soil beryllium in several countries

Beryllium and aluminium contents in uncontaminated soils from six countries are reported. The means and ranges of beryllium in the surface soils were as follows: 1.43(0.20–5.50)g g^–1 in Thailand (n=28), 0.7 (0.31–1.03) g g^–1 in Indonesia (n=12), 0.99(0.82–1.32) g g^–1 in New Zealand (n=3), 0.58(0.08-1.68)g g^–1 in Brazil (n=16), 3.52(2.49–4.97)g g^–1 in the former Yugoslavia (n=10), and 1.56(1.01–2.73) g g^–1 in the former USSR (n=8). The mean and range of beryllium contents of the surface soils in Japan (1.17(0.27–1.95)g g^–1 n=27) are situated within the values of the soils from these countries except for the Yugoslav soils derived from limestones. The mean of the mean beryllium contents of the surface soils in all these countries is 1.42 g g^–1 which will be used as a tentative average content of beryllium in uncontaminated surface soils, except for the soils derived from parent materials high in beryllium content. The beryllium contents of the subsoils were higher than those of the surface soils in New Zealand and Yugoslavia as is the case with Japan. The correlation coefficient between the contents of beryllium and aluminium in all the soil samples (n=113) including surface soils and subsoils was 0.505 (p < 0.001).     

Temporal variation and distribution of trace metals in freshwater and fish from Calabar River, S.E. Nigeria

An investigation on the abundance and distribution of trace metals (Fe, Cu, Zn, Mn, Cr, Cd and Pb) in water, and nine species of fish samples from Calabar river was carried out in 1992. The concentrations of iron (6000–7240gl^–1), zinc (4910–7230gl^–1), and cadmium (3–7gl^–1) showed moderate pollution while those of copper (420–630gl^–1), manganese (23–48gl^–1), chromium (<10–20gl^–1) and lead (<1–10gl^–1) in water were well below WHO permissible levels. Significant seasonal changes (0.001p0.25) were obtained for iron, copper, zinc, manganese and cadmium in water. Furthermore, iron, zinc and cadmium showed statistically significant spatial changes (0.005p0.10). Of the nine fish species studied, no statistically significant relationship between body weight and the concentrations of the metals was observed. The concentrations of the metals per mean total body weight apparently decreases in the order Fe>Zn>Cu>Mn>Pb>Cd=Cr and were within the limits that were safe for consumption.     

The unusual metal status of the dugong Dugon dugon

Using atomic absorption spectroscopy, exceptionally high concentrations of iron (778 to 82,363 g g⁺¹ dry weight) and zinc (219 to 4,183 g g⁺¹ dry weight) were detected in the livers of Dugong dugon (Müller) from north Queensland compared with reported values for other marine mammals from other areas of the world. Levels of copper (9.1 to 608 g g⁺¹ dry weight), cadmium (<0.1 to 59 g g⁺¹ dry weight), cobalt (0.5 to 72 g g⁺¹ dry weight) and silver (0.2 to 39 g g⁺¹ dry weight) in the liver, and cadmium (0.2 to 209 g g⁺¹ dry weight) in the kidney were also relatively high in several samples, whilst concentrations of nickel, lead and chromium were consistently below the limits of detection in all tissues. Manganese concentrations, in all tissues examined, were generally comparable with those reported from other marine mammals. Tissue concentrations of a number of metals varied with the age of the dugong. Levels of iron, zinc, cadmium and cobalt in the liver zinc and cadmium in the kidney, and iron in the muscle were significantly positively correlated with age. Copper and manganese in both liver and kidney were negatively correlated with age. Large deposits of the iron-rich pigment, haemosiderin, the quantity of which also tended to increase with age, was a conspicuous feature of the livers of all the post-natal dugongs examined histologically. It seems unlikely that the unusual metal status of the dugong reflects anthropogenic activities, since many individuals were collected in remote areas far from major sites of urbanization and industrialization. Seagrasses, the major food of dugongs, were collected from various north Queensland dugong habitat-areas and analysed. Very high concentrations of iron but low levels of copper were detected. The significance of such dietary imbalances and their possible influence on the metal status of the dugong were therefore considered.     

Effect of ionizing radiation on haemoglobin of marine lamellibranchs

The effect of ionizing radiation on the iron-linked protein (haemoglobin) of the marine lamellibranchs Anadara granosa (Linn.) and Cardita antiquata (Lam.) from Bombay waters, India is discussed. Purified haemoglobin solutions were exposed to a ⁶⁰Cobalt source delivering a dose of about 4,600 rad/min, at the sample irradiation point. Radiation damage or degradation was measured spectrophometrically by studying changes in the absorption spectra following irradiation in the presence and absence of oxygen. Exposure to ionizing radiation in general caused a decrease in absorption of both haemoglobins, irrespective of location, viz extra-versus intracellular, at Soret (412 m), (540 to 42 m) and (574 to 76 m) peaks, and an increase in absorption at 510 and 630 m. Upon exposure to a higher dose, O₂Hb of C. antiquata showed an increase in absorption at the protein peak (280 m); exposure to a lower dose, however, resulted in decreased absorption. Furthermore, the changes following irradiation were dependent upon the initial state of the pigment. Oxyhaemoglobin, when exposed to radiation, oxidized to hemiglobin, and hemiglobin reduced to oxyhaemoglobin. The extracellular haemoglobin of high molecular weight (3x10⁶) of the false cockle C. antiquata was found to be extremely radio-resistant, whereas intracellular haemoglobin of low molecular weight (74,000) of the arcid clam A. granosa was highly radiosensitive, since it could not be exposed to doses exceeding 18,000 r.     

Photosynthesis-irradiance responses and photosynthetic periodicity in the sea anemone Aiptasia pulchella and its zooxanthellae

Sea anemones (Aiptasia pulchella) containing zooxanthellae (Symbiodinium microadriaticum) were maintained in a long-term laboratory culture on a 12 h light (100 E m^-2 s^-1):12 h dark cycle. Photosynthetic oxygen production was measured for the symbiotic association and for freshlyisolated zooxanthellae. Light utilization efficiencies () were similar for both sets of zooxanthellae, suggesting negligible shading of zooxanthellae by animal tissue in this association. Whereas freshly-isolated zooxanthellae were photoinhibited at high irradiances (800 to 1 800 E m^-2 s^-1), zooxanthellae in the host continued to function at photosynthetic capacity. Time of day may influence photosynthetic measurements in symbiotic organisms, as it was found that photosynthesis in A. pulchella followed a diel periodicity at both light-saturating (1 200 E m^-2 s^-1) and subsaturating (150 E m^-2 s^-1) irradiances. There was a peak period of photosynthesis between 12.00 and 14.00 hrs. Light stimulated dark respiration rates of A. pulchella. Dark respiration of sea anemones increased somewhat towards the end of the light cycle and was always greater after exposure to high irradiances.     

Relationship between phytoplankton cell size and the rate of orthophosphate uptake: in situ observations of an estuarine population

Orthophosphate uptake by a natural estuarine phytoplankton population was estimated using two methods: (1) ³²P uptake experiments in which filters of different pore sizes were used to separate plankton size-fractions; (2) ³³P autoradiography of phytoplankton cells. Results of the first method showed that plankton cells larger than 5 m were responsible for 2% of the total orthophosphate uptake rate. 98% of the total uptake rate occurred in plankton composed mostly of bacteria, which passed the 5 m screen and were retained by the 0.45 m pore-size filter. There was no orthophosphate absorption by particulates in a biologically inhibited control containing iodoacetic acid. Orthophosphate uptake rates of individual phytoplankton species were obtained using ³³P autoradiography. The sum of these individual rates was very close to the estimated rate of uptake by particulates larger than 5 m in the ³²P labelling experiment. Generally, smaller cells were found to have a faster uptake rate per m³ biomass than larger cells. Although the nannoplankton constituted only about 21% of the total algal biomass, the rate of phosphate uptake by the nannoplankton was 75% of the total phytoplankton uptake rate. Results of the plankton autoradiography showed that the phosphate uptake rate per unit biomass is a power function of the surface: volume ratio of a cell; the relationship is expressed by the equation Y=2x10^-11 X ^1.7, where Y is gP m^-3 h^-1 and X is the surface: volume ratio. These results lend support to the hypothesis that smaller cells have a competitive advantage by having faster nutrient uptake rates.     

Modification of the feeding behavior of marine copepods by sub-lethal concentrations of water-accommodated fuel oil

The feeding behaviors of Acartia clausi and A. tonsa were measured in samples of water containing low levels of a water-accommodated fraction of No. 2 fuel oil. The copepods fed normally at a hydrocarbon concentration of 70 g l^-1, but their feeding behavior was altered both quantitatively and qualitatively at a concentration of 250 g l^-1. Three types of response to the higher oil level were found. The first was total suppression of feeding. Both other types involved suppression of feeding on particles between 7 and 15 m diameter, but one showed no change in the ingestion of larger particles, whereas the other displayed increased feeding on particles larger than 15 m diameter. These results suggest that the species of Acartia studied use three different modes of feeding, each on a different size range of particulate material. Low-level hydrocarbon pollution affects each feeding mode differently.Contribution No. 973, Center for Environmental and Estuarine Studies of the University of Maryland     

A comparative study of photoadaptation in four diatoms isolated as endosymbionts from larger foraminifera

Four endosymbiotic diatoms were isolated from 2 species of larger foraminifera collected in the Red Sea and Hawaii. The photoadaptive responses of the cultured diatoms were measured at 312, 19 and 7 W cm^-2. Two of the diatoms (Fragilaria shiloi and Nitzschia laevis), both isolated from Amphistegina lessonii, grew fastest at 312 W cm^-2. The other two diatoms (N. valdestriata and N. panduriformis) which were isolated from Heterostegina depressa, grew best at 19 W cm^-2. Of the four diatoms, F. shiloi grew best at high light levels. Also in F. shiloi, chlorophyll c content per cell was directly proportional to light intensity; in contrast chlorophyll a and carotenoids increased to maxima at 19 W cm^-2. The chlorophyll a and c and carotenoid content of N. valdestriata were also maximal at 19 W cm^-2. Photosynthetic rates, measured by respirometry, suggested that the diatoms were photoinhibited at higher light intensities and did well at moderately low light intensities (175W cm^-2). The photocompensation points of all 4 diatoms were about 2% of the light available in the spring at 1-m depth at Elat on the Red Sea. At Elat the photocompensation point would lie between 40 and 50 m if the algae were free in nature. The amount of attenuation of light by the shells of the host has not yet been measured. Presumably photocompensation of the algae within hosts is reached at depths less than 40 m.     

Uptake of glucose by bacteria in the sediment

A method is described for the incubation of undisturbed sediment cores under in situ conditions with the addition of low concentrations of ¹⁴C-glucose. Data are presented for respiration, gross uptake and actual uptake rate of glucose by bacteria in sandy, wave-washed beaches of the Baltic Sea. On the average, the bacteria respired 8% of the total glucose taken up. The gross uptake measured was between 2.3×10^-3 and 6.8×10^-3 g ¹⁴C-glucose g sediment^-1 (dry weight) h^-1 (average 4.7×10^-3 g g^-1 h^-1). Minima in the gross uptake rate corresponded with maxima in the concentration of natural free dissolved glucose. For the actual uptake rate, however, very similar uptake rates were calculated for the sediments examined (between 1.4×10^-1 and 1.9×10^-1 g glucose g^-1 h^-1, average 1.7×10^-1 g g^-1 h^-1).Publication No. 183 of the Joint Research Program at Kiel University (Sonderforschungsbereich 95 der Deutschen Forschungsgemeinschaft).     

Lead exposure in Saudi Arabia from the use of traditional cosmetics and medical remedies

Twenty Henna samples were collected and analysed for lead by electrothermal atomic absorption spectrophotometry after a microwave acid digestion procedure. The mean lead concentration was 5.50 g g^–1, with a range from 1.29 g g^–1 to 16.48 g g^–1. The data did not show a high concentration of lead in these samples. However, if we take into account the popular use of henna, the cumulative effects of prolonged exposure to low lead especially in children cannot be ruled out.