Functional morphology and feeding behavior of Paraprionospio pinnata (Polychaeta: Spionidae)

The functional morphology and feeding behavior of Paraprionospio pinnata (Ehlers) were studied. The tentacular feeding palps of P. pinnata possess four groups of cilia: laterals, latero-frontal cirri, frontals and basal transverse rows. The lateral cilia beat in metachronal waves creating in current that flows toward the frontal surface of the palp. The latero-frontal cirri deflect suspended particles onto the frontal surface and potentially resuspend deposited particles. The frontal cilia line the groove of the palp and transport particles to the ciliated pharynx. The basal transverse cilia also beat in metachronal waves and together with the frontal cilia of the branchiae produce a U-shaped current that removes particles rejected by the pharynx from the burrow. The significance of particle selection at the site of the pharynx in spionid polychaetes is hypothesized to be constrained by the interaction of specific morphologies and behaviors that reduce the effects of epifaunal predation and browsing. The relationship between sediment permeability and type of respiratory or ventilation current is hypothesized to be a potentially important factor in understanding the distribution of spionid polychaetes.     

Particle capture in the crown of the ciliary suspension feeding polychaete Sabella penicillus: videotape recordings and interpretations

An experimental setup was designed for in situ videotape recording of the particle capture process in the crown of the polychaete Sabella penicillus. Intact individuals of S. penicillus (collected in the Gullmornfjord, Sweden in 1992) were exposed to either 6 m Latex spheres or Rhodomonas sp. flagellate cells (6 m). The capture of the added particles was recorded on video. From frameby-frame analyses particle velocities were estimated and the shape of the three-dimensional particle paths was inferred. The mean velocity of particles approaching the crown was estimated to be ca. 1 mm s^-1, increasing to ca. 1.7 mm s^-1 in the interpinnule channel. At the moment of capture the particles were seen to follow a curved, near circular path close to the tips of the latero-frontal cilia. The transport velocities on the frontal side of the pinnules and filaments were estimated to be up to 0.15 and 0.5 mm s^-1, respectively. Counting captured particles relative to particles arriving within the area of the pinnules gave a rough, direct estimate of nearly 100% retention rate when the polychaete was feeding undisturbed. Together with results from clearance measurements in the literature this implies that the worm is able to capture particles down to 3 m entering the interpinnule channel almost 100% effectively. In view of the 80-m wide interpinnule channel and 40-m spacing between the tips of the latero-frontal cilia on both sides of the channel, this result cannot be explained by mechanisms based solely on direct mechanical contact between cilia and particles but must involve fluid mechanical mechanisms. The present work is the experimental basis for ongoing numerical simulations of the particle motion in the interpinnule channel.     

Fluid motion and particle retention in the gill of Mytilus edulis: Video recordings and numerical modelling

Particle trajectories of 6.4m Latex spheres were recorded by video, both near an isolated blue mussel, Mytilus edulis, gill filament and, in place of an intact interfilamentary canal, in a model canal of width 200, 100 or 70m, formed by a transparent plate positioned next to a gill filament. Each arrangement was placed in a 2 x 10 x 10 cm test vessel filled with seawater. Serotonin (nerve-transmitter) stimulation was used to activate lateral cilia and to either lock latero-frontal cirri at the end of an active stroke (10^-5 M), or to activate them (10^-6 M), yielding lateral cilia beat frequencies of 19 and 16 Hz, respectively. With latero-frontal cirri locked, image analysis of particle tracks gave maximum velocities of ca. 2.9±0.2mm s^-1 close to the tips of lateral cilia, for both isolated filament and model canal cases. Experimental velocity profiles along the 200-m wide model canal were recorded and used as good approximations to the fluid velocity because of the low Reynolds number. A two-dimensional steady model was proposed for the gill pump, assumed to only comprise lateral cilia. This model was solved numerically for the experimental model, canal in the vessel and the results showed satisfactory agreement with experimental volocity profiles from particle tracks. The numerical approach was also applied to a model of a single interfilamentary canal in the vessel. The resulting mean velocity in the canal was 1.70 mm s^-1, but the resistance to flow in the model was less than that in an intact mussel gill. Video graphs of particle tracks indicated that active latero-frontal cirri play a role in the transfer of particles from through current to frontal current, probably by means of a strong interaction through the motion of intervening fluid rather than through a direct physical contact. M. edulis specimens used in the present study were collected in 1990 at Helsingør and in 1991 at Kerteminde, Denmark.     

Larval development in the Antarctic nemertean Parborlasia corrugatus (Heteronemertea: Lineidae)

Embryonic and larval development were followed from fertilisation to settlement in the Antarctic heteronemertean Parborlasia corrugatus (McIntosh, 1876). The first cleavage occurred 10 to 15 h after fertilisation, and the second at 17 h. Larvae hatched at the gastrula stage, between 170 and 200 h post-fertilisation, and were 150 m in diameter. Early larval stages aggregated in dense groups near the surface of incubation vessels and were positively phototactic. Early pilidium larvae were recognisable 435 h post-fertilisation. They were 155×152 m in size, and possessed a complete apical tuft of cilia and a full marginal band of locomotory cilia. At this stage, the gust was visible through the body wall, and the mouth was open and was 40 m in diameter. Late pilidia, 222×193 m in size, were helmet-shaped. They had an apical tuft over 100 m long, and possessed a lobed marginal band of locomotory cilia. Pilidia were observed aggregating close to the bottom of incubation vessels 1200 to 1350 h (50 to 56 d) after fertilisation, and this was interpreted as settlement behaviour. At this stage, the apical tuft had been lost and they were highly contractile, being capable of compressing their bodies. However, neither developing juveniles within the larval envelope nor hatched juveniles were observed. Pilidia consumed the microalgae Tetraselmis suecica, Thalassiosira pseudonana and Isochrysis galbana. They also fed on particulate organic material < 1 m in size, as shown by the presence of material in the guts of larvae offered filtered extracts of algal cultures. There was some indication that larvae could use dissolved organic material, since pilidia held in seawater with organic material removed did not survive as long as those in filtered seawater or in filtered water with added amino acids. However, the only larvae to exhibit settlement behaviour in the feeding experiments were those offered Tetraselmis succica and Thalassiosira pseudonana, and these required a longer development time to reach this stage than pilidia in the standard cultures, where a mixed algal diet was offered.     

The role of male vs male interactions in maintaining population dialect structure

Summary Nonmigratory populations of Whitecrowned Sparrows in coastal California exhibit dialects in territorial male songs that are stable in space and time. By field playback experiments, we tested a prediction from the hypothesis that male aggressive interactions prohibit mixing of song dialects. Playback of the home dialect Clear song to territorial males singing the Clear dialect resulted in less response than that given to playback of the neighboring Buzzy dialect. Response to both Buzzy and Clear dialect songs by target Clear males, however, was greater than that given to the Bodega dialect recorded 55 km away (Figs. 2 and 3). We conclude that these results are consistent with the hypothesis that male-male aggressive interactions play an important role in reducing dialect mixing.     

Particle capture in the musselMytilus edulis: The role of latero-frontal cirri

Microscope video graphs of particle paths near one-filament-thick mussel gill preparations, stimulated with a nerve transmitter (10^–6 M serotonin which restores normal ciliary activity), were used to disclose the capture of 6 m algal cells. Suspended algal cells carried with the water were stopped for a while at the entrance to the interfilament gap by the action of the latero-frontal cirri (Ifc), and transferred to the frontal side of the filament to be transported towards the marginal food groove. The event of transfer took place during approximately a time interval of 1150 to 1/25 s. To gain a better understanding of the capture mechanism and retention efficiency versus particle size, the flow through and around the Ifc was theoretically estimated. Normally beating Ifc create periodic, unsteady, three-dimensional flows at the entrance to the interfilament canal. During the active beat most of the water is deflected to flow around the branching cilia of the Ifc while some of the water is strained by these. Large particles (> 4 m) are stopped and transferred to the frontal current, whereas smaller particles either follow the flow around the Ifc and escape or they are stopped by the branching cilia.     

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     

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.     

Size composition of particulate organic matter in the lagoon of Tikehau atoll (Tuamotu archipelago)

Suspended particulate matter was comprehensively investigated from 6 to 17 April 1986 in the lagoon of Tikehau atoll (15°00S; 148°10W). Dry weight (DW), particulate organic carbon (POC), adenosine triphosphate (ATP), and chlorophyll a were measured for five size-classes (0.2 to 0.8 m, 0.8 to 3 m, 3 to 35 m, 35 to 200 m, and 200 to 2000 m). Taxa were identified and counted for the whole plankton (both autotrophic and heterotrophic). Particles <3 m accounted for 81% of the total POC (192 mg m^-3), and detritus comprised 82% of the total POM. Phytoplankton (cyanobacteria plus algae) accounted for 35% of the living carbon, 75% of which consisted of heterotrophic bacteria and cyanobacteria. The zooplankton biomass was composed of 31% nano-, 26% micro-, and 43% mesoplankton.     

A preliminary assessment of the main causative mechanisms of the “island mass” effect of Barbados

Nutrient enrichment of inshore waters is considered the ultimate cause of the island mass effect of Barbados, and other tropicalislands. The present study is an evaluation of the three principal causative mechanisms of enrichment of Barbados coastal waters, i.e. run-off from land, a nutrient exchange between the benthos and overlying waters and internal waves of lunar periodicity. Attempts to link high precipitation to high primary production rates or low salinity with high nutrient levels were unsuccessful. This suggested that land-drainage was not an important factor. Comparisons of nutrient concentrations and C₁₄ fixation rates in waters overlying two contrasting (sand and coral) benthic situations showed trends rather than statistically valid differences in these production variables. A simple calculation of potential nutrient supply versus actual demand showed that internal waves represent a potential source of enrichment. It is suggested that internal waves contribute to the observed high levels of standing crop and production which are characteristic of an island mass effect.     

The structure of the latero-frontal cirri on the gills of certain lamellibranch molluscs and their role in suspension feeding

Photomicroscopy and scanning electron microscopy were used to determine the fine structure of the latero-frontal cirri on the gills of three species of bivalve mollusc: Mytilus edulis Linn., Barnea candida (Linn.), and Petricola pholadiformis Lam. The component cilia are seen to branch off alternately along the length of each cirrus. Each of these free, lateral lengths of the cilia are separated from the next on their side by a mean distance of 0.6 m. They extend to a mean length of 2.7 m in M. edulis, the species described in detail. It is shown that a complete straining mesh can be formed over the gill ostium during normal filtering and the aperture of this mesh correlates well with the previously recorded filtering efficiency for Mytilus.     

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.     

Physiology of the digestive tract of the sedentary polychaete Terebellides stroemi

The digestive tract of the sedentary polychaete Terebellides stroemi, collected from 88 m depth on the French Catalan Coast, was studied using histological, biochemical, cytological and spectrographic techniques. The ciliated oesophagus possesses a ventral pharyngeal pouch with a muscle bulb. The stomach is divided into two parts, the fore stomach is ciliated, but the hind stomach takes the place of a gizzard with a thick peritrophic membrane and a thick muscle mantle. The digestive gland enters the digestive tract at the boundary of the two stomachal areas; it is comprised of epithelial lamellae with a glandular epithelium. The gland cells contain a spherocrystal secretion with a high calcium and phosphorus content. The cells are also absorbant due to their microvillar brush border and to the storage of glycogen and lipids in the basal epithelium. A biochemical study using the Apizym System confirmed the secretion of enzymes such as phosphatases, esterases and various carbohydrases. Tryptic and chymotryptic enzymes were visualized by biochemical hydrolysis of synthetic substrates. The epithelium of the fore intestine is similar in appearance to the epithelium of the digestive gland, but consists of a single epithelial layer. Hind intestine and rectum are only excretory systems. The presence of this digestive gland does not seem to have been described elsewhere in polychaetes but is similar to the Morren's gland of some oligochaetes. The study was carried out during 1982 and 1983.     

Environmental influence on the locomotor activity rhythm of the sand-shore amphipod Talorchestia deshayesi

The precision and persistence of the nocturnal, surface locomotor activity rhythm of the sand-beach amphipod Talorchestia deshayesi is described. The rhythm is expressed as a circadian activity period with no evidence of a circa-tidal component associated with the time of high tide. The rhythm is light-sensitive and entrainment occurs in response to changes in the time of an experimentally simulated dusk transition. Locomotor activity is initiated at the end of the dusk transition with cessation always occurring prior to dawn. The point of activity initiation is taken to be the position of a synchronizing cue controlling entrainment. The cue appears to be an absolute irradiance level of approximately 1.0 to 2.0×10^-4 W m^-2     

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.     

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.     

Lead Contamination of Topsoil and Vegetation in the Vicinity of a Battery Factory in Nigeria

Levels of Pb, Zn, Cu, Cr, Ni and Cd were determined in topsoil and vegetation in the vicinity of a factory manufacturing lead- batteries in Ibadan, Nigeria. The samples were collected along five transects in different directions, and varying distances up to 1000m from the factory. Soil lead levels were found to be elevated around the factory, with average levels of about 2000mgkg^–1 close to the fence that declined gradually to about 50mgkg^–1 some 750m away. Soil-lead level around a primary school located about 500m from the factory was as high as 1450mgkg^–1. Lead levels were equally elevated in the vegetation, though average levels in vegetation were slightly lower than in the soil. Cadmium concentrations in soil and vegetation, though low, were more positively correlated with lead levels than any of the other metals are with lead.     

Development of the pericalymma larva of Solemya reidi (Bivalvia: Cryptodonta: Solemyidae) as revealed by light and electron microscopy

Solemya reidi Bernard 1980 is a gutless protobranch bivalve known to possess intracellular chemoautotrophic bacterial symbionts in its gill. A light and electron microscope study on the embryology and larval development of S. reidi provides data for the bivalve Subclass Cryptodonta. S. reidi spontaneously spawned large eggs (271 m in diameter), which developed within individual gelatious egg capsules. The first several cleavages were equal and a distinct molluscan cross was formed at the animal pole of the embryo, features previously unreported in bivalve development. Lecithotrophic pericalymma larvae (similar to the larvae of paleotaxodont protobranch bivalves and aplacophoran molluscs) hatched at 18 to 24 h and remained in the water column for a further 5 d at 10°C. At hatching, larvae measured from 360 to 440 m in length and from 225 to 265 m in cross-sectional diameter. Definitive adult structures developed within an epithelial locomotory test entirely covered with compound cilia. The test histolysed at metamorphosis and was ingested throught the mouth into the perivisceral cavity. Length and height of the shell following metamorphosis was 433 m (±42 m, n=16) and 282 m (± 29 m, n=13), respectively. Primary data and data from the literature show that the type of larval development in both paleotaxodont and cryptodont bivalves cannot be reliably estimated from egg or prodissoconch sizes.     

Information transfer and gain in flocks: the effects of quality and quantity of social information at different neighbour distances

We assessed experimentally how the quality and quantity of social information affected foraging decisions of starlings (Sturnus vulgaris) at different neighbour distances, and how individuals gained social information as a function of head position. Our experimental set up comprised three bottomless enclosures, each housing one individual placed on a line at different distances. The birds in the extreme enclosures were labelled senders and the one in the centre receiver. We manipulated the foraging opportunities of senders (enhanced, natural, no-foraging), and recorded the behaviour of the receiver. In the first experiment, receivers responded to the condition of senders. Their searching rate and food intake increased when senders foraged in enhanced conditions, and decreased in no-foraging conditions, in relation to natural conditions. Scanning was oriented more in the direction of conspecifics when senders behaviour departed from normal. In the second experiment, responses were dose dependent: receivers increased their searching rate and orientated their gaze more towards conspecifics with the number of senders foraging in enhanced food conditions. In no-foraging conditions, receivers decreased their searching and intake rates with the number of senders, but no variation was found in scanning towards conspecifics. Differences in foraging and scanning behaviour between enhanced and no-foraging conditions were much lower when neighbours were separated farther. Overall, information transfer within starling flocks affects individual foraging and scanning behaviour, with receivers monitoring and copying senders behaviour mainly when neighbours are close. Information transfer may be related to predation information (responding to the vigilance of conspecifics) and foraging information (responding to the feeding success of conspecifics). Both sources of information, balanced by neighbour distance, may simultaneously affect the behaviour of individuals in natural conditions.Communicated by H. Kokko     

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.