Suspension-feeding by herbivorous calanoid copepods: A cinematographic study

Many planktonic calanoid copepods are commonly described as filter-feeders. Direct observations using high-speed micro-cinematography indicate that these animals are suspension-feeders. They capture and handle the food particles not passively according to size and shape but, in most cases, actively using sensory inputs for detection, motivation to capture, and ingestion.     

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.     

Food size spectra,ingestion and growth of the copepodAcartia tonsa during development: Implications for determination of copepod production

Clearance rates on different sizes of spherically shaped algae were determined in uni-algal experiments for all developmental stages (NII through adult) of the copepodAcartia tonsa, and used to construct food size spectra. Growth and developmental rates were determined at 7 food levels (0 to 1 500 g C l^-1 ofRhodomonas baltica). The lower size limit for particle capture was between 2 and 4 m for all developmental stages. Optimum particle size and upper size limit increased during development from 7 m and 10 to 14 m for NII to NIII to 14 to 70 m and 250 m for adults, respectively. When food size spectra were normalized (percent of maximum clearance in a particular stage versus particle diameter/prosome length) they resembled log-normal distributions with near constant width (variance). Optimum, relative particle sizes corresponded to 2 to 5% of prosome length independent of developmental stage. Since the biomass of particulate matter is approximately constant in equal logarithmic size classes in the sea, food availability may be similar for all developmental stages in the average marine environment. Juvenile specific growth rate was exponential and increased hyperbolically with food concentration. It equaled specific female egg-production rate at all food concentrations. The efficiency by which ingested carbon in excess of maintenance requirements was converted into body carbon was 0.44, very similar to the corresponding efficiency of egg-production in females. On the assumptions that food availability is similar for all developmental stages, and that juvenile and female specific growth/egg-production rates are equal, female egg-production rates are representative of turnover rates (production/biomass) of the entireA. tonsa population and probably in other copepod species as well. Therefore, in situ estimates of female fecundity may be used for a rapid time- and site-specific field estimate of copepod production. This approach is shown to be fairly robust to even large deviations from the assumptions.     

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.     

Aggregation and foraging behavior of whirligig beetles (Gyrinidae)

Summary Whirligig beetles aggregate in the daytime into dense single-and multispecies groups (rafts) of hundreds or thousands of individuals. On the 22km shoreline of Lake Itasca in northern Minnesota, these aggregations were on the average 0.8 km apart, and they were usually found day after day in the same ocations.Most beetles apparently do not home to the aggregation of their origin after dispersing at night because (a) the species composition of some aggregations changed greatly, and (b) paint-marked beetles (Dineutus horni) moved overnight from one aggregation as far as 4km, joining 11 of the 14 large (>300 beetles) D. horni groups on the lake.Throughout the night, the largest concentrations of beetles remained within 100m of the diurnal aggregation sites. Beetles reconvened into the compact rafts before daybreak, in part by following each other in sometimes long single files or trains. Their forward motion stopped after they joined large number of other beetles. We infer that following behavior enables those individuals that have dispersed from their original aggregations (during their nocturnal foraging) to find and join other aggregations before daylight.Naive fish ate the beetles despite their noxious secretions. However, fish living near rafting sites and feeding on insects on the water surface in daylight should soon learn to avoid the beetles. The rafting sites would then become safe places. We observed fish attacking only those beetles that had been either dispersed from their rafts or released into open water away from raft sites in the daytime. We speculate that the evolutionary significance of the aggregation behavior is related to predator (fish) avoidance.     

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.     

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.     

Evaluation of Public Housing Lead Risk Assessment Data

A unique data set from lead risk assessments performed on 67 public housing developments from across the United States was made available for analyzes. The data set includes results of lead analysis from 5906 dust wipes and from 1222 soil samples. A total of 487 dwelling units in these developments, as well as associated common areas, were sampled, all by the same team of inspectors. The number of dwelling units within a development that were sampled reflected the guidelines then in force, the 1990 Interim HUD Guidelines, rather than those specified in the 1995 Guidelines. Median dust lead loadings for floors, 151gm^–2 (14gft^–2), and window sills, 936gm^–2 (87gft^–2), were much less than former HUD limits of 1076gm^–2 (100gft^–2) and 5380gm^–2 (500gft^–2), respectively and are only about one-third of the recently established limits of 431gm^–2 (40gft^–2) and 2690gm^–2 (250gft^–2). In contrast, the median lead loading for window troughs, 8560gm^–2 (795gft^–2), was almost identical to the HUD clearance limit of 8610gm^–2 (800gft^–2). There was a strong positive correlation between floor and window trough lead loading values for samples from the same dwelling units and those from common areas of the housing developments. Door threshold samples, which may reflect conditions exterior to the dwelling unit, were collected from 53 dwelling units. Median lead loading levels of these samples were more than ten times higher than those in floor samples from the same dwelling units, were about the same as window sill samples and about one-half of levels in window trough samples. Composite sample results, simulated by averaging results from four samples within a dwelling unit, revealed that in order to have the same rate of excedence of standards, the composite standards would have to be reduced, for example, from the single sample value of 1076gm^–2 (100gft^–2) to 527gm^–2 (49gft^–2) for floor samples and from the single sample value of 8610gm^–2 (800gft^–2) to 5160gm^–2 (479gft^–2) for window troughs. For this public housing data set, the portion of the units in developments containing more than 225 units which exceeded the established limit for window samples was the same when using either the full data set or a random one-half of the data set. This suggests that, for this data set, the number of dwelling units sampled was excessive . Thus, the required increase in the number of dwelling units to be sampled specified in the 1995 Guidelines for developments with more than 225 dwelling units, may not have been necessary if this data set is representative of public housing developments in the United States.     

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.     

Reproductive biology of commercially exploited deep-water royal red prawns (Haliporoides sibogae,Solenoceridae) in south-east Australia

Deep-water royal red prawns (Haliporoides sibogae de Man, 1907; Solenoceridae: Penaeidea) were sampled from commercial catches off south-east Australia between November 1988 and May 1990. Four stages of sexual development were distinguished macroscopically for each sex. For the females, histology and analysis of oocyte size were used to validate the macroscopic staging of ovaries into undeveloped, developing, early ripe and ripe. Females were larger than males, reaching a maximum size of 46 mm carapace length (CL) compared to 32 mm CL for males. Average size at sexual maturity was 30.8 mm CL for females and 25.8 mm CL for males. Females apparently breed several times in their life, whereas males probably breed only once. Individual fecundity (ranging from about 58 000 to 140 000 oocytes) was relatively low compared with other penaeids, but oocytes were larger (mean diameter=0.41 mm). Two short breeding seasons occurred per year (February to April and July to August). There was a clear size-related latitudinal distribution of the prawns, with largr prawns (spawners) being more abundant in the northern region of the fishing area, and juveniles (CL20 mm) being more abundant in the south. Most of the spawning stock probably lies outside the main fishing ground, while the fishery targets mainly prawns below the size at maturity.     

Costs and consequences of variation in the size of ruff leks

Summary We studied 13 ruff leks in a small region on the island of Gotland (Sweden) to investigate the effect of lek size on the costs and benefits of lekking for individual males. Male ruffs occur in two behaviourally and morphologically distinct forms, independents (residents plus marginals) and satellites, whose costs and benefits we have assessed separately. These ruff leks had from 1–10 resident (territory-holding) males and were visited daily by satellites, marginals and females from 5–25 May, when most copulations occurred. We used the average number of independent males, counted during censuses taken every 5 min during 2-h observation periods at each lek, as an index of mean lek size. Per independent male, the numbers of both satellites and females increased significantly with mean lek size. Female arrival rate and attendance (total female-minutes) also increased significantly with mean lek size as did the average per capita rate of mating success for resident males (that of satellites was not quite significant). Thus, the dispersion of both of these male categories did not appear to fit an ideal free distribution with respect to mating success. In addition, the number of independent-independent fights per independent and the rate of satellite-resident dyad formation per resident increased significantly with mean lek size. These results suggest that ruffs on larger leks enjoy higher mating success than those on smaller leks but also that costs increase with lek size. We suggest that independent males distribute themselves so as to maximize their own net benefits and that this factor can account for both the occurrence of ruff leks and the variation in their size. Correspondence to: J. Höglund     

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.     

Vigilance and foraging substrate: anti-predatory considerations in a non-standard environment

Summary The commonly studied standard anti-predatory environment presents animals with spatially-distinct feeding sites and refuges from attack, neither of which necessarily obstructs predator detection. In contrast, tree-trunks provide animals with a markedly non-standard environment in which the foraging substrate itself may be a refuge from attack that unavoidably obstructs predator detection. Thus anti-predatory behavior in this environment should be influenced not only by a perceived risk of attack, but also by the nature of the refuge/foraging substrate itself. Downy woodpeckers (Picoides pubescens) are a common tree-trunk foraging animal, and an experimental analysis of their behavior suggests that they respond appropriately to their non-standard anti-predatory environment. In particular, anti-predatory vigilance varies strongly with changes in tree trunk diameter. Two modes of vigilance were apparent. In stationary vigilance, woodpeckers maintained the position of their feet while rotating their bodies side-to-side to peer around the trunk; mobile vigilance involved movement around the trunk itself. Both the frequency and angle of rotation of stationary vigilance increased with trunk diameter, as did the frequency of mobile vigilance. The woodpeckers also held their heads farther away from the trunk surface as diameter increased. All of these measures of vigilance increased under a greater perceived risk of predation. As might be expected given these results, downy woodpeckers avoided thick trunks; they did not, however, prefer the thinnest (least obstructive) available trunks. These preferences may reflect the influence of trunk diameter on thermo-ecological and/or anti-predator considerations not related to vigilance. Overall, this arboreal environment provides an unusual perspective on anti-predator decision-making with several implications for tree-trunk foraging animals in general.     

Tit for tat among neighboring hooded warblers

Summary The dear-enemy relationship of territorial songbirds could be mutually beneficial to neighbors, as males who recognize neighbors and reduce their responses to these neighbors would require less time and energy for territorial defense. In order for this relationship to be evolutionarily stable, this reduction in response to a neighbor must be conditional on reciprocal restraint by that neighbor. This study examined the possibility of such conditional responses in hooded warblers (Wilsonia citrina). Responses of territorial hooded warblers to playbacks of neighbors' songs from shared boundaries were measured before and after playbacks that simulated intrusions of those same neighbors (NNNN treatment) or strange birds (NSSN treatment) into the subjects' territories. Each male received both treatments separated by at least 8 days. Males increased their responses to playbacks of a neighbor's songs at the boundary after simulated intrusions of that same neighbor (NNNN) but did not increase their responses to such playbacks after simulated intrusions of strangers (NSSN). This increased response to a defecting neighbor suggests that the relationship between neighboring territorial hooded warblers is based on a conditional strategy like tit-for-tat.     

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     

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.     

Evidence for multiple recruitment-cohorts of Puget Sound Dungeness crab,Cancer magister

While sampling intertidally in Puget Sound, Washington, USA, for juvenile Dungeness crab (Cancer magister) in 1984, we found evidence of two distinct cohorts of the same year-class based on sizes of first-instar juveniles (J1) and the spatial/temporal patterns of settlement. In 1988, three distinct cohorts were observed to settle in Puget Sound and its approaches. Settlement of one cohort occurred during May in the Strait of Juan de Fuca and in those areas of Puget Sound closest to the Strait. J1 individuals of this cohort were large (x=7.4 mm carapace width, CW) and comparable in both size and timing of settlement to populations along the Washington coast (e.g. Grays Harbor and Willapa Bay). Initial settlement density of the May cohort was as high as 215 crabs/m² in intertidal eelgrass beds along the Strait of Juan de Fuca and decreased to <2 crabs/m² within Puget Sound and the Strait of Georgia. A second cohort apparently originated in Hood Canal (a deep inland fjord), its size upon settlement in June was significantly smaller (J1 x= 5.3 mm CW) than the May cohort, and it was limited to Hood Canal and areas of Puget Sound close to the mouth of Hood Canal. A third cohort, which settled in late July and August, was the smallest of the three cohorts (J1 x= 4.8 mm CW), and was widely distributed around Puget Sound from Seattle in the south to the USA/Canadian border in the north. We hypothesize that most juvenile recruitment in Hood Canal and Puget Sound originates from parental stocks endemic to their respective basins (Hood Canal and Puget Sound cohorts), but that, on occasion, oceanographic conditions allow substantial influx of Pacific Ocean Dungeness crab larvae (oceanic cohort) through the Strait of Juan de Fuca into Puget Sound. Tracking of spatial/temporal settlement patterns and comparison of J1 sizes proved useful for estimating the probable sources and dispersion of Dungeness crab larvae. Differences in size and time of settlement between various larval cohorts of C. magister may prove useful as biomarkers for tracing circulation patterns within and between inland waters of Washington and the Pacific Ocean. Causes of smaller size and later settlement of the Puget Sound cohort relative to oceanic conspecifics of the same year-class are discussed.Contribution No. 856, School of Fisheries, University of Washington, Seattle     

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.     

The distribution of heavy metals in deposited urban dusts and sediments, Coventry, England

Samples of urban dusts and sediments have been collected and categorised into three compartment those which act mainly as sources, those undergoing transport and those which have been deposited. The sediments were fractionated into <63m to match similar sized lacustrine sediments and <2mm to represent natural and anthropogenic fluvially transported sediments. Preliminary results of total heavy metals analysis show that the <2mm fraction of the source group exhibits the greatest variabilty in metal concentrations. Overall, however, the <63m fraction dominates regardless of compartment. Some heavy metal concentrations decrease through the sourcetransportdeposit process, possibly due to selective onward transport of finer material or other anthropogenic processes unique to the urban environment (e.g. street cleansing). Sitespecificity is indicated in a comparison with other similar studies.     

A Preliminary Study on Soil–Gas Radon Geochemistry According to Different Bedrock Geology in Korea

Three study areas of Kwanak campus (Seoul National University), Boeun (Choongbuk) and Gapyung (Kyonggi) were selected and classified according to their bedrock types in order to investigate soil–gas radon concentrations. The mean values of radon concentrations decreased in the order of Gapyung (40BqL^–1) > Kwanak campus (30BqL^–1) > Boeun (22BqL^–1), and decreased in the order of granite gneiss > banded gneiss > granite > black slate–shale > mica schist > shale–limestone > phyllite schist according to bed rock types. Variation in radon emanation with water content in soils and with soil grain size was assessed by the modified Morse (1976) 3min method. Soil–gas radon concentrations increased with increasing water content in the range of less than about 6–16wt.%, but decreased above 6–16wt.%. Radon concentrations also increased with decreasing soil grain size. Radioactivity analysis of radionuclides of ²³⁸U series in some soil samples indicated their possible radioactive disequilibrium between ²²⁶Ra and ²³⁸U due to the differing geochemical behaviour of intermediate radionuclides. Thus, a radioactive isotope geochemical approach should be necessary for soil–gas radon study.