Effects of salinity on fasted rainbow trout,Salmo gairdneri

Rainbow trout (Salmo gairdneri Richardson) which had been maintained for 120 days in salinities of fresh water, 7.5, 15.0 and 32.5 at 10°C were fasted for up to 48 days under these same environmental conditions. Live weight loss between Days 7 and 48 of starvation could be described by a straight line, as could the decrease in condition factor . Trout maintained in 32.5% S showed a significantly greater weight loss than those in salinities of 15.0 and below. Muscle water content increased slightly during fasting in fresh water, 7.5 and 15.0 S. In 32.5 S, however, muscle water fell significantly between Days 19 and 37. Liver water content also increased slightly during fasting, except in 32.5 S, where water content again decreased between Days 19 and 37. The volume of the gall bladder contents increased during fasting.     

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.     

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.     

Sublethal effects of zinc and municipal effluents on larvae of the red abalone Haliotis rufescens

Experiments were conducted to develop a sensitive sublethal toxicity test protocol to determine the toxicity of municipal wastewater effluents to larvae of the red abalone Haliotis rufescens. In multiple tests, fertilized abalone embryos were exposed for 48 h to dilutions of a reference toxicant, zinc sulfate, and to dilutions of primary-and secondary-treated effluents. The resulting veliger larvae were examined microscopically for larval shell abnormalities. In a longer flowthrough experiment, abalone were exposed for the entire larval phase, from the two-cell stage through metamorphosis, to compare zinc effects on metamorphosis with zinc effects on short-term larval shell development. Dissolved oxygen, pH, salinity and temperature were measured daily in test solutions, and zinc concentrations were verified by chemical analysis. No observed effect concentrations (NOECs) for zinc were 39±2.1 g l^-1 in three 48 h exposures, and 19 g l^-1 for the 9 d exposure through metamorphosis. Median effect concentrations (EC₅₀s) were 68±6.9 g l^-1 in 48 h tests and 50 g l^-1 in the 9 d test. Abalone larvae were affected at lower concentrations of primary than of secondary effluent.     

Circadian rhythmicity of locomotor behavior and oviposition in female Teleogryllus commodus

Summary Locomotor activity of the Teleogryllus commodus is under circadian control, with _LL=25.3 h and _DD=23.4 h. In LD 12:12 h, running occurs either exclusively during darkness (57%), mainly in the dark phase (35%), or with substantial activity peaks in both phases (8%). For oviposition, _LL>24 h and _DD<24 h; in LD 12:12 h, 80% of the studied deposited their eggs mainly during the light phase and 20% primarily during darkness. In the discussion, a temporal correlation between stridulation, spermatophore formation, and locomotion, and oviposition is established, which serves to make an encounter and mating between the sexes as likely as possible.Dedicated to Prof. Dr. M. Gersch on the occasion of his 70th birthday     

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.     

Populational distribution I: The digital simulation

This paper presents a method of investigating the distributional pattern of a biological population, using a technique of simulation. The method consists of the comparison of the empirical frequency curve of a population, obtained using the Method of Quadrats, with a simulated one, since the pattern of the simulated curve depends on the simulated distribution. An example is given.     

A Preliminary Study of Geographic Influence on Arsenic Concentrations in Human Hair

Past mining activities in the county of Cornwall in the United Kingdom, has exposed the local environment to raised levels of As. Previous research has shown an increased concentration of As in crops grown in such areas and the subsequent take-up of As through the food chain may lead to an increased body burden in man. In an attempt to evaluate this, a pilot study was carried out using Particle Induced X-ray Emission to compare the hair As concentration of a group of Cornish residents to that of a control group consisting of residents in the counties of Oxfordshire and Wiltshire. The null hypothesis being that there is no significant difference between the hair As concentrations of the two groups.Each group comprised thirty six age and sex matched subjects. The mean hair As concentration for the Cornish group was 2.51 g g-1, which is significantly greater than that of 0.7 g g-1 found in the control group (p = 0.004). The World Health Organisation suggests a hair As value greater than 1 g g-1 as evidence of increased exposure to As and 5 g g-1 is quoted by the Canadian Government as evidence of significant ingestion of As. Twenty one Cornish subjects registered a value at or above 1 g As g-1 compared to nine in the control group (p = 0.0003). Five subjects in the Cornish group had values that exceed 5 g As g-1, compared to only two in the control group (p = 0.23). We use the results of this study as evidence to support our continued work in this area in order to evaluate possible health implications.     

Stepwise acclimation—a method for estimating the potential euryhalinity of the gastropod Hydrobia ulvae

The White Sea gastropod Hydrobia ulvae (Pennant) was exposed to step-wise lowering or increase of the habitat salinity. The time allowed for acclimatization to the successive salinity levels was sufficient to complete non-genetic adaptation. In this way, the lower and upper salinity limits were extended. The tolerance limits obtained are assumed to be indicative of the capacity for non-genetic adaptation and to serve as a genotypical characteristic. The tolerance of specimens colleced from in situ conditions (mid littoral, 20 S) ranged between 14 and 34 S. After non-genetic adaptation, the lower tolerance value shifted to 6 S (adaptation limit), and the upper value to 76 S (final limit not reached). There is no reason for considering White Sea H. ulvae to represent a special physiological race of specimens from those on the coast of Great Britain.     

Changes in blood lead and water lead in Edinburgh. An eight year follow-up to the Edinburgh lead study

This study aimed to measure changes in household water lead and blood lead in young people living in Edinburgh over a period of 8 years. Two hundred and twenty-three families were eligible and 207 (93%) agreed to participate. A half-hour stagnation sample of kitchen cold water was taken from each household, and 171 young people (aged 14–17 years) provided a blood sample for lead analysis. Information on plumbing changes, exposure to other sources of lead and factors which might influence blood lead was collected by questionnaire. Edinburgh is supplied with water treated in one of two treatment plants. There was a different programme of water treatment in each plant. In one (A) lime and orthophosphate was introduced in the interval between the original and follow-up studies. In the other (F) lime treatment began before the original study and orthophosphate was introduced subsequently. In water from treatment plant A, mean water lead levels fell from 34 to 4.3 gL-1 (87%). In water supplied from treatment plant F the corresponding values were 9.3 to 3.6 gL-1 (61%). These reductions were due to both water treatment and removal of lead plumbing. Houses with no lead plumbing have water lead levels 89% lower than houses with lead tanks, and 47% lower than houses with lead pipes. About one-third of households with lead tanks are predicted to have water lead levels above the current EC limit of 50 gL- 1, though only 3% or less of the remaining households would exceed this limit. If the proposed 10 gL-1 limit were introduced, 34% of households supplied from plant A and 25% from plant F would breach the limit. Blood lead levels fell from an average of 11.0 gdL-1 to 4.0 gdL-1. Males had higher values than females and the main factors influencing levels were water lead and age of house. Our results show substantial reductions in household water lead and blood lead in our sample over a period of 8 years and represent an important achievement in public health. However, more progress will be required if the proposed new limit of 10 gL-1 for water lead is to be met. There is a need for the continuing surveillance of household water lead and blood lead levels in representative samples of the population.     

Compositional topography of melon and spermaceti organ lipids in the pygmy sperm whale Kogia breviceps: Implications for echolocation

The forehead of the pygmy sperm whale Kogia breviceps contains a large melon of fatty tissue in front of a small, fat-filled, cornucopia-shaped spermaceti organ. This unique anatomical structure may possibly play an acoustical role in the whale's echolocation system, similar to the fatty melon sound lens postulated for dolphins. To better understand its function, we have studied the compositional topography of the K. breviceps melon and spermaceti organ lipids. The fatty head tissues of an adult K. breviceps were serially sectioned into 9 transverse slices. Appropriate tissue samples were cut from every other slice, and analyzed for % lipid and lipid class composition. Wax esters and triglycerides were the only major lipids present; their average carbon number in each sample was determined by gas-liquid chromatography (GLC). Our topographical analyses of K. breviceps melon indicate 3 regions of distinctive lipid composition: a fat-poor melon exterior, an outer melon of medium fat content having % triglyceride>% wax ester, and a fat-rich inner melon having % wax ester>% triclyceride. The spermaceti organ contains a fat-rich core of very high wax-ester content (84 to 99%), surrounded by a fat-poor case. Average carbon numbers of both wax esters and triglycerides were lowest in the inner melon and the spermaceti organ. At the rear of the spermaceti organ lies the museau de singe, an apparent sound generator. The lipid topography data plus anatomical and acoustical considerations suggest that the K. breviceps melon/spermaceti organ system may function as an acoustical transducer, directing and refracting sound waves from this source for the purpose of echolocation.     

High turnover of inorganic carbon in kelp habitats as a cause of δ13C variability in marine food webs

In a study to assess qualitatively the importance of organic matter derived from kelp production in the Aleutian Islands of subarctic Alaka, replicated samples of autotrophic sources and primary and secondary consumer organisms were sampled for ¹³C among sources, sites, (treatment) islands, and years. Unanticipated variation in the ¹³C of kelps occurred among overtly similar sites at different islands. Variation in the ¹³C of the surface canopy-forming kelp Alaria fistulosa was particularly extreme, ranging from-15.5 to-28.0 compared to the understory kelps, Laminaria spp. A. fistulosa ¹³C varied by as much as 6 to 7 among similar sites at a given island within years, and by as much as 3 to 4 between years at the same sampling site. In serveral cases, ¹³C variation was weakly tracked by some consumer organisms, suggesting that even detritus pathways through the food web can be localized and tightly coupled. Dynamic cycles in the concentration and ¹³C of dissolved inorganic carbon (DIC) and aqueous CO₂ concentration ([CO₂]_aq) were measured at three sites on one island. The ¹³C or organic carbon fixed by A. fistulosa, calculated from diurnal DIC concentration and ¹³C measurements, varied by 15 and varied inversely with [CO₂]_aq concentrations. Local DIC variability, probably resulting from high productivity and decreased turbulence in dense kelp habitats, provides a possible mechanism of variation in kelp ¹³C. The short-term variability in the ¹³C of organic carbon fixed by kelps indicates that sampling methodology and design must assess this potential variation in marine macrophyte ¹³C before making assumptions about the transfer of ¹³C-invariate organic matter to higher trophic levels. On the positive side, a predictable relationship between [CO₂]_aq concentration and kelp ¹³C offers a potentially robust means to assess productivity effects on CO₂ limination in kelps and other complex aquatic macrophyte habitats.     

An advantage to mate choice in the seaweed fly,Coelopa frigida

Summary All natural populations studied of the seaweed fly, Coelopa frigida, are polymorphic for the inversion system on chromosome I. It has previously been shown that heterokaryotypes have superior egg-to-adult survival than either homokaryotype, and that there is non-random mating with respect to inversion genotypes. We have inquired whether the production of fitter progeny in larger numbers is the possible reason for the existence of non-random mating behaviour. We measured the fertility, fecundity and progeny survival of adults that have either been allowed to exercise mate preference, or been given a single, randomly chosen, mate. The fertility (% of females producing progeny) and progeny survival (% of larvae surviving to the late 3rd instar stage) are both significantly greater in choice than nochoice females. There are also significant differences in fertility and progeny survival depending on whether the parents were of similar or dissimilar inversion genotypes. An effect of relative adult size on fertility was also observed. There appear to be no effects of mate choice on fecundity. Indirect evidence is presented that adults are choosing their mates not only on the basis of genotypes but on other criteria as well. It is suggested that the superior reproductive performance of animals allowed a choice of mates may account for the evolutionary origin and continued existence of mate discrimination. Furthermore, since over 25% of the genome of Coelopa is located within inversions, the observed pattern of negative assortative mating may maintain a substantial fraction of the genes in a polymorphic state.     

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.     

Digestive carbohydrases from the hepatopancreas of two Antarctic euphausiid species (Euphausia superba and E. crystallorophias)

The hepatopancreatic extracts of Euphausia superba Dana and E. crystallorophias Holt and Tattersall collected from the Antarctic. Ocean during January 1985, are most effective in hydrolysing substrates containing (13)--glucosidic linkages. Three enzymes appear to be involved in the depolymerization of (13)--D-glucans in the euphausiid diet: (1) an exo-(13)--D-glucanase, (2) an endo-(13)--D-glucanase and (3) a -D-glucosidase. The glucanases have a pH optimum of 5.4, a temperature optimum of 50°C and are optimally extracted in bistripropane buffer, pH 7.2. Levels of (13)-D-glucanase in laboratory-cultured E. superba are inversely affected by food availability, and activities double after starvation for 12 d. The increase is due mainly to higher activities of exo-acting glucanases. -Amylase and endo-(14)--D-glucanase (cellulase) activity are also present in the extracts in addition to glycosidase activity against a range of p-nitrophenyl substrates (-and -D-glocose, - and -D-galactose, -D-xylose, - and -D-mannose). Digestive activity against several acidic polysaccharides, including the acidic mucilage polysaccharide of the ice diatom Stauroneis amphioxys, is minimal and is not induced when the polysaccharide is present in the diet of E. superba. These results indicate that some, but not all, components of the algal material in the euphausiid diet can be hydrolyzed and assimilated.     

Environmental Accumulation of Airborne Fluorides in Romania

The nature and extent of pollution from an aluminium smelter and a fertiliser factory in Romania were studied. These are large industrial complexes, and both types of industry are known to release fluorides into the atmosphere. In grass samples collected from around the aluminium smelter, the maximum fluoride levels were found to be 4023mgkg^–1 and 162mgkg^–1 in unwashed and washed grass samples respectively, and 89mgkg^–1 in soils. For the fertiliser factory, the maximum levels in washed grasses were found to be 207mgkg^–1, and 11mgkg^–1 in the soils. In both locations, these maximum values were obtained in samples collected from within 200m of the factory limits, and compare with regional background levels of less than 10mgkg^–1 for grasses and 2mgkg^–1 for soils. The high fluoride levels of fluoride in the grasses are sufficient to give cause for concern for the effects that these could have on the local population and on grazing animals.     

Influence of salinity and temperature on the oxygen consumption in young juveniles of the Indian prawn Penaeus indicus

Routine oxygen consumption of very young juveniles (0.1 g) of Penaeus indicus H. Milne Edwards was significantly influenced by ambient temperature and weight of the animal, but not by ambient salinity, when tested at salinities (7, 21, and 35) to which they had been long-term (over 10 days) acclimated. Standard oxygen consumption of young juvenile prawns (1 to 3 g), subjected to step-wise changes in ambient salinity, from sea water to low salinity waters (2 to 6), and measured after short-term (24 h) salinity acclimation at each step, was lowest at salinities where prawns such as those tested occur naturally (10 to 15). The metabolic rates do not appear to have a direct relation to the osmotic gradient, even when the influence of interfering activity is eliminated. It appears that factors other than osmotic gradient will have to be sought in order to explain the metabolic patterns of P. indicus in relation to salinity.     

Vibrational communication between hitchhikers and foragers in leaf-cutting ants (Atta cephalotes)

Abstract In a foraging column of the leaf-cutting ant Atta cephalotes, minim workers (the smallest worker subcaste) hitchhike on leaf fragments carried by larger workers. It has been demonstrated that they defend leaf carriers against parasitic phorid flies. The present study examines the cues used by the potential hitchhikers to locate leaf carriers. As recently reported, foraging workers stridulate while cutting a leaf fragment, and the stridulatory vibrations serve as closerange recruitment signals. We tested the hypothesis that these plant-borne stridulatory vibrations are used by the potential hitchhikers to locate workers engaged in cutting. Three different lines of evidence support this view. Firstly, the repetition rate of the stridulations produced by foraging workers increases significantly as foragers maneuver the leaf fragment into the carrying position and walk loaded to the nest. This is the moment when hitchhikers usually climb on the leaf. Although the leaf-borne stridulatory vibrations are considerably attenuated when transmitted through the workers' legs, they can nevertheless be detected at short distances by minims. This subcaste is several times more sensitive to substrate-borne vibrations than larger workers. Secondly, when a stridulating and a silent leaf were simultaneously presented at the foraging site, minim workers spent significantly more time on the stridulating than on the silent leaf. Thirdly, hitchhiking was more frequent in leaf carriers which cut fragments out of the stridulating leaf than in those cutting the silent leaf.Abstract In a foraging column of the leaf-cutting ant Atta cephalotes, minim workers (the smallest worker subcaste) hitchhike on leaf fragments carried by larger workers. It has been demonstrated that they defend leaf carriers against parasitic phorid flies. The present study examines the cues used by the potential hitchhikers to locate leaf carriers. As recently reported, foraging workers stridulate while cutting a leaf fragment, and the stridulatory vibrations serve as closerange recruitment signals. We tested the hypothesis that these plant-borne stridulatory vibrations are used by the potential hitchhikers to locate workers engaged in cutting. Three different lines of evidence support this view. Firstly, the repetition rate of the stridulations produced by foraging workers increases significantly as foragers maneuver the leaf fragment into the carrying position and walk loaded to the nest. This is the moment when hitchhikers usually climb on the leaf. Although the leaf-borne stridulatory vibrations are considerably attenuated when transmitted through the workers' legs, they can nevertheless be detected at short distances by minims. This subcaste is several times more sensitive to substrate-borne vibrations than larger workers. Secondly, when a stridulating and a silent leaf were simultaneously presented at the foraging site, minim workers spent significantly more time on the stridulating than on the silent leaf. Thirdly, hitchhiking was more frequent in leaf carriers which cut fragments out of the stridulating leaf than in those cutting the silent leaf.Communicated by P. Pamilo     

Mesopelagic-boundary community in Hawaii: Micronekton at the interface between neritic and oceanic ecosystems

The present study demonstrates that a distinct land-associated community of mesopelagic micronekton exists around the Hawaiian Islands. This mesopelagic-boundary community replaces the oceanic mesopelagic community over bottom depths of approx 400 to 700 m and includes about 14 species of fishes, 5 of shrimps and 4 of squids. Similar species of the mesopelagic micronekton have been reported in association with other landmasses at the boundary between the oceanic mesopelagic realm and upper continental or island slopes. These species may form a cosmopolitan mesopelagic-boundary community which shows regional differences in taxonomic composition, abundance and diversity. Boundary communities, with populations which are both tightly constrained geographically and relatively accessible to shore-based research programs, offer unique opportunities for studying biological processes of the mesopelagic realm and the interactions between neritic and oceanic populations. Data is presented from three midwater and two neuston sampling projects undertaken around the main Hawaiian Islands between 1987 and 1989; additional evidence from the literature is also discussed.     

Night irradiance and synchronization of lunar release of planula larvae in the reef coral Pocillopora damicornis

Pocillopora damicornis (Linnaeus), which is known to release planula larvae on a monthly cycle, was grown in full daytime solar irradiance, but with four treatments of night irradiance: (1) natural night irradiance, (2) shifted-phase (total darkness during nights of full moon with artificial irradiance at lunar intensity on nights of new moon), (3) constant full moon (full lunar irradiance every night), and (4) constant new moon (total darkness every night). The reproductive cycle of the corals held in the shifted-phase treatment moved out of synchrony with the cycle of corals exposed to a natural lunar cycle of night irradiance. Two previously described types of P. damicornis were tested. The Type Y normally start releasing larvae at full moon, with peak production at third quarter. In the shifted-phase treatment they began releasing planulae at new moon (artificial full moon), with peak production at first quarter. The Type B corals, that normally start releasing planulae at new moon with peak production at first quarter, began to release planulae at full moon (artificial new moon), with peak production at third quarter. Populations of corals grown either in the constant full moon or constant new moon treatment quickly lost synchronization of monthly larva production, although production of planulae continued. Thus spawning is synchronized by night irradiance.Contribution No. 702 of the Hawaii Institute of Marine Biology