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.     

Distribution of algae on tropical rocky shores: spatial and temporal patterns of non-coralline encrusting algae in Hong Kong

Encrusting algae have been described as dominant space occupying species on rocky shores around the world. Despite their abundance, however, most studies classify species under generic names (e.g. Ralfsia sp.) or as a functional group (e.g. encrusting algae), thereby underestimating the number of species present and their ecological importance. Studies on six rocky shores of varying exposure, in Hong Kong, recorded eight common species of encrusting algae. The greatest abundance of encrusting algae was recorded on shores of intermediate exposure, where four distinct zonation bands could be identified; a cyanobacterial Kyrtuthrix-Zone in the upper midlittoral, a Bare-Zone below this, a Mixed-Zone in the lower midlittoral and a Coralline-Zone in the infralittoral fringe. Abundance declined on shores of greater and lower exposure to wave action, where bivalves and barnacles were competitively dominant. Certain species were found in greater abundance on exposed shores (e.g. Dermocarpa sp. and Hildenbrandia occidentalis), while others preferred more sheltered shores (e.g. Hildenbrandia prototypus and Kyrtuthrix maculans). With the exception of some cyanobacterial crusts, the abundance of encrusting algae was always greatest towards the low shore, an area of decreased physical stress and increased herbivore density. Zonation patterns showed seasonal variation associated with the monsoonal climate of Hong Kong. Most species increased in abundance during the cool season, while during the summer months the cover and vertical extent of encrusting algae decreased in relation to summer temperatures, although K. maculans increased in abundance during the summer. On Hong Kong shores, encrusting algae have a high species richness and exhibit within-functional group spatial and temporal variation which is mediated by herbivory and seasonal, physical stresses.     

Allozyme and colour differences between two sibling species of the heteronemertean Lineus torquatus from the Sea of Japan

Brown and cherry colour morphs of the heteronemertean Lineus torquatus Coe, 1901 from the Vostok Bay of the Sea of Japan were compared using allele frequencies at 18 isozyme loci. These morphs shared no common alleles at 9 of the 18 loci. The observed genetic differences are strong evidence that the brown and cherry colour morphs, which occur sympatrically, are different species. Nei's genetic distance between these species (D=1.135) is considerably higher than typical D values for congeneric animal species. As with much previous work on nemerteans, intraspecific allozymic variability in both species was high, with mean expected heterozygosity values 0.286±0.049 and 0.159±0.051 for L. torquatus (brown) and L. torquatus (cherry) species, respectively.     

Temperature acclimation and other influences on embryonic duration in the copepod Pseudocalanus sp.

Embryos of Pseudocalanus sp. captured near Halifax, Nova Scotia, Canada, in spring take longer to develop than do those from the warmer waters of summer and autumn. This is related to the larger size of females and their eggs in the colder seasons. An experiment revealed size-assortative mating and the influence of male size as well on embryonic duration. The seasonal change is contrary to the slight reduction of embryonic duration after short-term cold acclimation of females in the laboratory. There is no evidence that embryos in the cold season develop more rapidly than expected from the overall relationship between embryonic duration and female size. However, they do, like embryos after short-term cold acclimation, develop relatively more rapidly at low temperatures; i.e., there is clockwise rotation of the rate-temperature response, equivalent to the temperature adaptation that has been demonstrated among species of copepods. This seasonal rotation may also be related to seasonal variations in size, since larger females from a given season produce embryos that show such rotation. Thus, there is no evidence for seasonal compensation as a consequence of temperature acclimation underlying changes that are attributable to differences in size. Evidently there is also a strong genetical component in duration of development of embryos produced by individual females.     

Arsenic tissue concentration of immature mice one hour after oral exposure to gold mine tailings

A potentially high bioavailability of arsenic in gold mine tailings from a site in northern California has been suggested by solubility studies. To help address this issue, an in vivo dosing study was conducted using 12dayold Swiss Webster mouse pups (n=8/group). A sample of sizefractionated mine tailings from the site (<20m particle size, 691g g^–1 arsenic) was prepared as an aqueous suspension and administered by gavage in a volume that provided 4mg As/kg body weight. The control group received the same volume of a commercial soil (1g g^–1 As) of similar particle size (<60m). No mortality or toxic signs were noted in either group. Tissue samples were collected 1h after gavage, freezedried, microwavedigested and analysed for arsenic by ICP/MS (detection limit 2ng As g^–1 dry weight). Arsenic concentrations (ng As g^–1 dry weight) in tissues from the pups who received mine tailings were significantly higher than in control tissues. The mean elevation in arsenic concentration was highest in the liver (3364% of control, p<0.0001), followed by blood (818 of control, p<0.0001), skin (207% of control, p=0.07), and brain (143% of control, p<0.0001). The carcass arsenic concentration (excluding the GI tract, liver, brain and skin) was 138 of control (p=0.02). The data indicate uptake of arsenic from weathered mine tailings by the immature mouse pups after oral exposure.     

“Copper” granules in the barnacle Balanus balanoides

Balanus balanoides (L.) collected from an area with high heavy-metal run-off contained two different types of granule within the parenchyma cells of the prosoma. X-ray microprobe analysis shows one to be the familiar zinc granule made up of concentric layers and giving major peaks for phosphorus and zinc, and the other to be homogeneous and giving peaks for sulphur and copper. This latter granule is designated the copper granule. Whilst zinc granules are known to be composed of inorganic phosphate, various tests on copper granules in sections and in a granule-rich pellet have shown that the copper is probably complexed with organic matter. The tests also demonstrated the relatively, insoluble (inert) nature of these granules. Although zinc and copper granules were present together in the prosoma, atomic absorption analyses of whole bodies (prosoma+thorax) have shown the level of zinc (50.28 g/mg dry weight) to be much higher than that of copper (3.75 g/mg dry weight).     

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 structure of plankton communities of the Indian Ocean

Species diversity and trophic structure of plankton communities have been considered as most important biological features. The Fisher () and Simpson () indices and the information index H=- pi log₂ pi (Margalef) were used for evaluation of species diversity. The indices have been calculated within the group of filter feeders by numbers ( and H) and biomass ( and H) of the species; the best results were obtained in the latter case. The index H=- pi log₂ pi is proposed for the quantitative evaluation of trophic structure, where a portion of an individual trophic group is taken as pi. The plankton material was collected by the R.V. Vityaz in the northern Indian Ocean in January through February, 1960. Analysis of characteristics of zooplankton distribution, species and trophic diversity in connection with characteristics of the water regime resulted in the definition of 3 types of the plankton communities: (a) those in intensive divergence zones; (b) those in poor divergence zones; (c) those in regions with stable water stratification or with feebly marked convergence, distiguished by different values of biomass, species diversity, and trophic group ratios.     

Indoor and outdoor household dust contamination in Cincinnati, Ohio, USA

Despite some progress in reducing the average lead level in the USA, the streets of Cincinnati, Ohio, are still contaminated by heavy metals. High levels of heavy metals will have significant unequivocal ecological impacts and pose a potential health hazard. This study evaluates the level of heavy- metal contamination in household dust and examines its relationships with the external environment. Samples of outdoor and indoor dust were collected from middle-income residential homes in the Greater Cincinnati Metropolitan District and the metal content was analysed by inductively coupled plasma atomic emission spectrophotometry. Results showed that the mean levels of lead in outdoor and indoor dusts are 650 g g-1 and 377 g g-1 and the copper levels are 253 g g-1 and 510 g g-1, respectively. The median levels are 156 g g-1 and 139 g g-1 for outdoor and indoor lead dusts and 35 g g-1 and 124 g g-1 for outdoor and indoor copper dusts. The degree of contamination may be ascribable to the age of the dwelling unit and the neighbourhood, the time when the unit was last painted, the presence of pets and the type of space heating. In addition, car exhausts seems to be a possible source of contamination.     

Genetic variation and biochemical systematics in the marine bryozoan Alcyonidium mytili

For many years the taxonomic position of the marine ctenostome bryozoan Alcyonidium mytili Dalyell (1848) has been in doubt, with some authorities regarding it as being conspecific with A. polyoum (Hassall). We have set out to resolve this problem using enzyme electrophoresis to examine the genetics of the population structure in the two species. The results show beyond reasonable doubt that sympatric populations of the two species are indeed from quite separate and non-interbreeding gene pools. An examination of various allopatric populations shows a new species of A. mytili to exist sympatrically with the other at Langstone Harbour, Hampshire, England. This species can be readily distinguished on morphological as well as genetic ground. Samples of A. mytili from Guernsey also show substantial genetic differences from other populations examined. It is tentatively concluded that this population also represents a separate gene pool and consequently should be recognised as a third species of A. mytili.     

Environmental Geochemistry of Soils and Waters of Susaki Area, Korinthos, Greece

Soil and water samples were collected from the Susaki area of Korinthos and analysed for heavy metals in order to evaluate their environmental impact. The geology of the studied area includes ultrabasic rocks and Neogene and Quaternary deposits whereas magnesite veins are found within the ultrabasic rocks. In the north part of the studied area post volcanic emissions of H₂S, CO₂ and H₂O vapor continue to the present day. All the samples were analysed for heavy metals by the ICP method. The element ranges (in g g^–1) for soil samples are: Cu 11–63, Pb 5–256, Zn 21–604, Ni 183–2665, Co 12–124, Mn 456–1434, As 5–104, Sr 44–730, V 21–84, Cr 163–2346, Ba 48–218, Zr 3–41, Y 3–13. The metals Pb, Zn, Ni, Co, Cr, Fe, Cu, Mn, As and Sr are enriched in the Susaki soils. The element ranges for water samples are: Cu 65–103ppb, Pb<10ppb, Zn<5ppb, Ni 21–163ppb, Co 2–12ppb, As<30ppb, Cr<20ppb, Ba 36–785ppb, Sb<10ppb, W<10ppb, Bi<30ppb, Mn 0.0–0.9 g g^–1, Fe 0.01–0.22 g g^–1, Na 843–3076 g g^–1, K 98–278 g g^–1, Si 39–65 g g^–1, P 0.1–0.2 g g^–1. There is a natural pollution of soils with elevated concentrations of Ni, Co, Mn, Fe and Cr due to the presence of ultrabasic rocks. Another natural case of As pollution of soils is due to the volcanic activity and the geothermal field in the area. The geochemical data of ground waters and also the ¹⁸, D data showed a mixing in different proportions between sea water and meteoric water.     

Lead-based paint in dwellings: The potential for contamination of the home environment during renovation

The quantity and particle size characteristics of lead in dust released during three different paint removal techniques was determined under controlled conditions and in situ in a dwelling. Air-lead and deposited dust-lead levels were highest after sanding but burning-off and hot-air removal methods also produced significant contamination. The importance of dust particle-size and lead is discussed in relation to the potential hazard to home renovators via inhalation and to children via the hand-to-mouth route.This paper is also being published in Proceedings of the Conference on Lead in the Home Environment and is one of several selected from SEGH sponsored conferences for simultaneous publication in this journal.     

The effect of a “permanent” clock-shift on the orientation of experienced homing pigeons

Summary A group of experienced homing pigeons vas subjected to a 6 h slow shift of their internal clock and kept under these conditions for more than 2 months. During the overlap time between the natural and artificial photoperiods they were released for training flights to familiarize them with an area while living in a permanent shift.Tested outside the permanent shift training range, the experimentals always deviated about 30° clockwise from the mean of their controls, markedly less than in a regular 6 h slow shift. Inside the permanent shift training range, however, they oriented like the controls (Fig. 2). When their internal clock was returned to normal, the birds showed a larger counterclockwise deflection on their first flight, which was roughly comparable to the effect of a regular 6 h fast shift (Fig. 3). On later flights after normalization, this large shift was no longer found; instead we observed a roughly 30° counterclockwise deflection when they were released inside the permanent shift training range in the morning. This deflection did not seem to occur in the afternoon or outside the permanent shift training range (Figs. 4, 5), and it disappeared when the birds were repeatedly released from the same site (Fig. 6).The occurrence or non-occurrence of the deflection was independent of the duration of the shift or the time passed after normalization; it seemed to depend solely on whether the birds had become familiar with a given site in the situation of the permanent shift. This argues against an effect based on the sun compass. We tend to assume that the still unknown navigational map is involved. In this case, however, as the deflection is independent of the home direction and the type of release site bias, the factors in question would act very differently from the gradients on which the traditional concepts of the navigational map are based. The processes establishing and updating the map and their possible differences are discussed.Died on August 17, 1980     

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.     

Aqua regia extractable trace elements in surface soils of venezuela

Surface soils (0–15 cm) were sampled at 10–20 km intervals along two transects in Venezuela. One (1162 km, 70 samples) ran west to east parallel with the Caribbean coastline, the other (920 km, 92 samples) ran south to north from the frontier with Brazil to the Caribbean shore. Sampling took place in both a wet and a dry season. Trace metals were extracted from dried, sieved (<2 mm) soil with boiling aqua regia followed by analysis by ICP or flame AAS. Metal values did not differ significantly between the two seasons and dates were averaged. Geometric mean values for the west–east transect were: Cr=41.5, Cu 17.9, Cs 3.6, Li=13.9, Mn=294, Ni=21.3, Pb=17.4, Sr=39.4, V=60.4 and Zn = 83.7g g^–1, respectively. Similarly, for the south–north transect Cr=21.3, Cu=4.3, Cs=1.1, Li=2.0, Mn=55.7, Ni=4.4, Pb=6.1, Sr=13.3, V=28.2 and Zn=16.7g g^–1, respectively. A classification of samples by lithology showed surface soil composition to be related to rock composition. Metal values were low in the soils in the south of the country, in the Guyana highlands (Gran Sabana). Low Zn contents were prevalent. Lead contents were affected by roadside fallout from vehicles using leaded petrol except that high Pb contents of soils in the Gran Sabana were of more complex origin.     

Primary production in Dumbell Bay in the Arctic Ocean

Photosynthesis, chlorophyll, inorganic nutrients, and related factors were measured throughout a productive season in a small coastal inlet of the Arctic Ocean. Significant production was confined to 5 m for a very limited time period beacause of both light and nutrient limitations. Maximum chlorophyll was 8.2 mg Chl a m^-3 and maximum gross and net photosynthesis rates were 830 and 550 mg C m^-2 d^-1. Annual gross and net photosynthesis is estimated at about 12 and 9 g C m^-2 respectively. The effect of light stimulation on assimilation is described, sources of coastal zone nutrient enrichment are considered, and discrepancies between gross and net photosynthesis are discussed with reference to the growth characteristics of the phytoplankton population.Bigelow Laboratory for Ocean Sciences. Contribution No. 76008     

Web tension and gravity as cues in spider orientation

Summary The bowl and doily spider, Frontinella pyramitela (Araneae, Linyphiidae), typically hangs at the lowest point on its concave upward, bowlshaped web (Fig. 1). It returns to the same area after prey capture, courtship, or repulsion of intruders, and naive spiders of either sex come to rest at the same center of preference.Because the center of preference is not visibly different from other parts of the bowl sheet, it is not obvious what cues the spiders use in establishing its location. Investigation of the roles of gravity, web curvature, thread density and web tension reveals the center of preference to be an area no different from others with respect to curvature and thread density but different with respect to tension. Tension in the web is locally high at the center, drops as one moves toward the periphery of the bowl, and rises again at the periphery (Fig. 6). The natural relationship between gravity and the orientation of the bowl is not a necessary condition in defining the location of the center of preference but gravity is involved in orienting the search for its location (Figs. 3, 4). Altering the pattern of web tension by cutting the tensor threads destroys the accord among spiders as to the location of the center of preference and confirms the role of web tension in the orientation of this spider.     

Conditional lekking in ruff (Philomachus pugnax)

Summary In our study of ruff, a lekking shorebird, we found that the lek ratio — the proportion of the total population of males occurring on leks was low, averaging 12% over the breeding season (Fig. 1D). Off-lek males spent approximately the same proportion of time as lek males in displaying to females (Fig. 4). We defined three spacing tacties that male ruffs use to position themselves to court females: Following — directly pursuing females, and two types of lekking behavior, Intercepting — waiting for females at resource-rich sites, and True Lekking — waiting for females at places without any resources other than the males themselves. Males switched among these tactics, causing the lek ratio to vary over the season (Fig. 1 D). Lek ratio increased when the number of females present in the study area plummeted at the end of May, and was positively correlated throughout the season with the copulation rate of the preceding day, suggesting that males were tracking the behavior, as well as the number, of females available (Table 1, Fig. 1). Early in the season, males off leks spent most of their time feeding (Fig. 4), and lek ratio was positively correlated with temperature (Table 1), suggesting that some males may have been unable to lek during cold weather. Males on leks mated at significantly higher rates than Followers (Table 4). On average, males at our interception lek were less site faithful and less peristent than males at true leks, and the interception lek itself disappeared after females stopped coming to use its adjacent resource (Table 2, Fig. 5). The most successful individuals in our population were the True Lekking males, rather than the Interceptors.In addition to the conditinal lekking tactics described here, ruff display a dimorphism in behaviorat leks. Independent males defend small courts on leks, while Satellite males share courts and mutually display with independents Both independents and satellites may use all three conditional tactics. We propose that satellites evolved as specialized. Followers, adept at tracking the movements of females among leks.     

Dependence of consumers on macroalgal (Laminaria solidungula) carbon in an arctic kelp community: δ13C evidence

Stable carbon isotope measurements (¹³C) were used to assess the importance of kelp carbon (-13.6 to-16.5) versus phytoplankton carbon (-25.5 to-26.5) to resident fauna of an isolated kelp bed community on Alaska's north arctic coast from 1979 to 1983. The predominant kelp, Laminaria solidungula, showed some seasonal variation in ¹³C which was correlated with changes in the carbon content of the tissue. Animals that showed the greatest assimilation of kelp carbon (>=50%) included macroalgal herbivores (gastropods and chitons,-16.9 to-18.2), a nonselective suspension feeder (an ascidian,-19.0) and a predatory gastropod (-17.6). Animals that showed the least incorporation of kelp carbon into body tissues (<=7%) included selective suspension-feeders (hydroids, soft corals and bryozoans,-22.8 to-25.1). Sponges, and polychaete, gastropod and crustacean omnivores exhibited an intermediate dependence on kelp carbon (15 to 40%). Within some taxonomic groups, species exhibited a broad range in isotopic composition which was related to differences in feeding strategies. In the polychaete group alone, ¹³C values identified four major feeding habits: deposit-feeders (-18.0), omnivores (-20.4), predators (-22.2) and microalgal herbivores (-23.0). Distinct seasonal changes in the ¹³C values of several animals indicated an increased dependence on kelp carbon during the dark winter period when phytoplankton were absent. Up to 50% of the body carbon of mysid crustaceans, which are key prey species for birds, fishes and marine mammals, was composed of carbon derived from kelp detritus during the ice-covered period.