Compositional topography of melon lipids in the Atlantic bottlenosed dolphin Tursiops truncatus: Implications for echo-location

Major variations in lipid composition exist within the fatty melon tissue of the Atlantic bottlenosed dolphin Tursiops truncatus. Topographical lipid analyses indicate a central inner melon core surrounded by distinctive outer melon, under melon, and blubber tissues. Acoustical considerations suggest that this melon-lipid topography may aid in collimation of the ultrasonic pulses used by the dolphin for echolocation.     

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.     

Grazing and ingestion rates of nauplii,copepodids and adults of the marine planktonic copepod Calanus helgolandicus

The average grazing and ingestion rates of all stages of the marine planktonic copepod Calanus helgolandicus (Calanoida) from nauplius stage IV to adults were measured experimentally at 15°C in agitated cultures. The chain-forming diatom Lauderia borealis and the unarmoured dinoflagellate Gymnodinium splendens were offered as food. The food concentrations were close to natural conditions and ranged from 36 to 101 g of organic carbon per liter. The medium body weights expressed in g of organic carbon of almost all larval stages raised at 49 g C/1 were identical with the weight of the same stages caught in the Pacific Ocean off La Jolla, California, USA. In a log-log system, grazing and ingestion rates increased almost linearly with increasing body weight. Grazing rates ranged from 4 to 21 ml/day/nauplius stage IV to 286 ml to 773 ml/day/female. Ingestion rates increased from 0.2 g to 0.8 g C/day/nauplius stage IV to 18 g to 69 g C/day/female. Grazing and ingestion rates per unit body weight decreased gradually with increasing body weight. The daily ingested amount of food decreased from 292 to 481% of the body weight (g C) of nauplius stage V to 28–85% of the body weight of adult females. Grazing and ingestion performances of all stages increased with increasing particle size. Grazing rates decreased and ingestion rates increased with increasing food concentrations. The published data on food intake of the different age groups of C. helgolandicus show that the young stages of herbivorous planktonic copepods can play a major part in the consumption of phytoplankton in the sea due to their high grazing and ingestion rates.     

Fouling organisms in the port of Mar del Plata (Argentina). I. Siphonaria lessoni: ecological and biometric aspects

The present paper deals with ecological aspects of the pulmonate gastropod Siphonaria lessoni (Blainville, 1824), a common member of fouling communities in Mar del Plata's port (38°0817 S, 57°3118 W). Populations on colonized panels of an experimental raft were studied during three annual cycles, to determine feeding habits, growth and various factors which restrict their distribution on floating substrata. Although S. lessoni is harmless as a fouling organism, its grazing on the algal belt clears a part of the substratum's surface, which is then quickly colonized by truly aggressive organisms such as Balanus amphitrite.     

Influence of salinity on embryonic development and the distribution ofSepia officinalis in the Delta Area (South Western part of The Netherlands)

The effect of salinity on embryonic development ofSepia officinalis (cuttlefish) in the Delta Area (South Western part of The Netherlands) was investigated in 1988/1989, and compared with data concerning the distribution ofS. officinalis in the three main parts of this area: Oosterschelde, Westerschelde and Grevelingen. Embryos hatched in water collected at Yerseke (Oosterschelde), Vlissingen (Western part of the Westerschelde) and Bommenede (Grevelingen), i.e., at salinity values above 28.1, but not in water sampled at Hoedekenskerke and Hansweert (Middle and Eastern part of the Westerschelde; salinities below 22.0). Under laboratory conditions, using diluted Oosterschelde water, the highest hatching percentages ofS. officinalis were found at salinities above 29.8. Some embryos hatched at a salinity value of 26.5 but no hatching occurred at salinities below 23.9. In embryos exposed to salinity changes during late embryonic development, the developmental rate decreased at salinity values of 28.7 or less. Below 22.4 embryos with morphological malformations were found. It can be concluded that salinity is an important factor limiting the distribution ofS. officinalis in most parts of the Delta Area, with the exception of the Western part of the Westerschelde and the Grevelingen.Contribution no. 489 of the Library of the Delta Institute for Hydrobiological Research     

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.     

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.     

Ecological constraints on the behaviour of mother long-tailed macaques (Macaca fascicularis)

Summary The ecological consequence of the effects of different social conditions on the behaviour of females with infants were examined in two different-sized groups of long-tailed macaques (Macaca fascicularis) that inhabited adjacent home ranges in Gunung Leuser National Park in Indonesia. This study aims to test predictions of the within-group competition/predation avoidance hypothesis of social organization. Females, particularly those carrying an infant, are considered to experience the most direct effects of environmental constraints on fitness prospects. Data on maintenance behaviour, height in canopy and spatial position were collected for five mothers in a small group and eight mothers in a large group. Comparisons were made on the basis of group size and dominance rank. Mothers from the large group spent less time feeding on clumped fruits and more time foraging on dispersed food items. Lower-ranking mothers, undergoing the highest rate of within-group competition, foraged most. For macaques in the study area, predation risk is considered to decrease with height in the canopy. Mothers in the small group, assumed to be more susceptible to predation, remained substantially higher in the canopy than mothers in the large group. In both groups, mothers adjusted their height to their spatial position in the group. Lower-ranking mothers were more often found without neighbours, presumably to avoid feeding competition. As a result they stay higher in the canopy than higher-ranking mothers. The results clearly demonstrate that individual females in the same reproductive state and living in the same area, but in different social environments, adapted their behaviour according to the hypothesis. Correspondence to: D.R. Vos     

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.     

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.     

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.     

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.     

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.     

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.     

Lack of social entrainment of free-running circadian activity rhythms in the Australian sugar glider (Petaurus breviceps: Marsupialia)

Summary Social influence on circadian activity rhythms was investigated in the nocturnal Australian marsupial Petaurus breviceps. The activity of two and two was recorded electroacoustically and observed by an IR television camera in LD 12:12 (10¹:10^-1lx) and in LL (10^-1lx) when housed isolated and in pairs (+). In LD-entrained animals the average duration of locomotion, orientation movements, grooming and total activity is influenced by social housing, and individually different activity patterns are harmonized. In constant illumination conditions, however, the members of a pair are not mutually synchronized and free-run with different circadian periodlengths. Therefore social influence on the LD-entrained activity rhythm in Petaurus should be interpreted as social masking rather than direct influence on the circadian system.     

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.     

Concentrations of Mn,Fe, Cu,Zn and Cd in the mesopelagic decapod Systellaspis debilis from the East Atlantic Ocean

Specimens of the oceanic decapod Systellaspis debilis were collected from six sites in the East Atlantic Ocean between 1970 and 1984, and were analysed for Mn, Fe, Cu, Zn and Cd. The data confirm that there are small but significant differences in mean metal concentrations from some sites which showed no obvious pattern in relation to geographic location of the samples. As a result, ranges of site means are quoted as baseline levels for each metal (g g^-1 dry wt): 2.3 to 2.9 g Mn g^-1, 31.2 to 77.8 g Fe g^-1, 25.9 to 83.4 g Cu g^-1, 41.9 to 92.9 gZn g^-1, 11.1 to 31.8 g Cd g^-1. The concentration of cadmium in S. debilis from all sites was raised relative to cadmium concentrations reported for coastal decapods, perhaps as a result of dietary enrichment. Metal accumulation may provide useful information for understanding the complex feeding behaviour of many oceanic animals.     

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.     

Studies on the nutritional requirements of the larval stages of Penaeus japonicus using microencapsulated diets

Fatty acid biosynthesis in the larval stages of Penaeus japonicus Bate was examined by feeding microencapsulated diets containing (1-¹⁴C) palmitic acid, and fat-free diets supplemented with defined fatty acids. Highest larval growth rates were achieved on diets containing Tapes philippinarum lipid and, when defined fatty acids were substituted, on diets containing 20:63 fatty acid. The radioactive tracer experiments indicate that 16:17, 18:0 and 18:19 fatty acids may be synthesised from palmitic acid and that P. japonicus larvae may possess the ability to elongate 18:33 to 20:53 and 22:63, and 18:26 to 20:46. However, the rates of these reactions appear to be too slow to meet the larval requirements for essential fatty acids and the 3 series of polyunsaturated fatty acids must be provided in the diet.     

Capillary supply and mitochondrial volume density in the axial muscles of the mesopelagic teleost Argyropelecus hemigymnus

Quantitative measurements have been made on the ultra-structure and capillary supply to the axial muscles of the mesopelagic hatchet fish Argyropelecus hemigymnus (Cocco, 1829). Fish were collected at Eastern North Atlantic Ocean Station 10244, 32°48N; 31°15W during November 1980, from a depth of 480 to 550 m. Mitochondria with densely packed cristae occupy 44.3% of slow-fibre volume. Each myofibril is in direct contact with a mitochondrion. Compared with other fishes studied, the capillary supply to A. hemigymnus slow fibres is poorly developed. The average number of capillaries per fibre is 0.9, such that each m of capillary contact supplies 0.011 m² of fibre cross-sectional area. The capillary surface area (m²) supplying 1 m³ of slow-fibre mitochondria is 0.17 in anchovy (Engraulis encrasicolus), 0.14 in rat-fish (Chimaera monstrosa), 0.14 in tench (Tinca tinca), 0.16 in catfish (Clarias mossambica), and only 0.025 for A. hemigymnus. It is suggested that, relative to the former species, some modifications in factors determining tissue oxygenation (e.g. myoglobin concentrations, blood flow, perfusion distribution or haemoglobin) and/or mitochondrial respiration rate are required in order to match oxygen supply and demand to the slow muscle in A. hemigymnus.