Hyperbenthic crustacean fauna of the Gullmarfjord area (western Sweden): Species richness,seasonal variation and long-term changes

Distribution of 118 species of Amphipoda, Mysidacea and Decapoda, sampled in 1984 and 1985 with an epibenthic sledge along a transect from the Skagerrak to the inner Gullmarfjord (Sweden), is described. Amphipods were richest in species in the Skagerrak, while most mysid species were taken at the sill. Deca-impoverished and the Lilljeborgidae, earlier represented by three species, had disappeared since the 1930s. The changes are most likely caused by eutrophication of the fjord. and deep-basin samples; (III) sill samples; (IV) Skagerrak samples. Characteristic species of the groups were identified with a pseudoF-test. Detrended Correspondence Analysis indicated seasonal faunal changes at 42 and 72 m depths. At both depths a shift in numerical dominance from amphipods to mysids was found in winter. The most pronounced changes seemed to occur at 42 m. Changes in composition and abundance of species during a renewal of the bottom water indicated that mysids were influenced by presumed near-bottom currents, while amphipods and decapods were not. Comparison of the present amphipod fauna with the fauna in 1933–37 revealed significant differences. The fauna in the deep basin was impoverished and the Lilljeborgidae, earlier represented by three species, had disappeared since the 1930s. The changes are most likely caused by eutrophication of the fjord.     

Gill pump characteristics of the soft clamMya arenaria

Pumping rates in the soft clamMya arenaria, collected in June 1987 in the Great Belt, Denmark, were determined as rates at which clams cleared suspensions of algae,Dunaliella marina. The frictional resistance of the siphons to water flow was estimated by studying the effect of excision of the siphons at the base on the rate of water pumping. The frictional resistance was also calculated from the Poiseuille equation. Excision of the siphons had no measurable effect on the pumping rate, and calculations indicated pressure losses ranging between 0.3 to 1.2 mm H₂O. This is consistent with the conception that the capacity of filter feeding bivalves to process large amounts of water depends upon a low resistance to water flow in the siphons.     

Acid dissolution methods for heavy metals determination in pine needles

Microwave digestion procedures using HNO₃, HNO₃+H₂O₂, HNO₃+HClO₄, HF mixtures and dry ashing with HF were investigated for heavy metals analysis by either inductively coupled plasma-optical emission spectroscopy (ICP-OES) or ICP-mass spectrometry (ICP-MS) in pine needles. The HF digestion procedures gave about 1.5 times higher values than a mixture of HNO₃+H₂O₂ alone. For Ti determination in needles, the HF procedure using dry ashing is thus recommended. The mean concentrations amounted to 900 mg/kg for Fe and 21.8 mg/kg for Ti in needles collected at an area polluted by a stainless steel works. Those concentrations were 10.6 and 4.3 times higher than in needles collected at an area nearby a pulp mill complex (84.5 mg/kg Fe and 5.0 mg/kg Ti).     

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.     

Verteilung verkehrsbedingter Edelmetallimmissionen in Böden

Contents and distribution of platinum-group-elements (PGE) in soils caused by automobile emissions were investigated at three transects perpendicular to the road at various depths. Concentrations of platinum, rhodium and palladium were determined by ICP-MS after separation and preconcentration by nickel-sulphide fire-assay. Platinum contents in roadside soils range from 250 μg/kg to the local background values which are below 0.5–0.8 μg/kg. Ratios of platinum and rhodium (about 6∶1) are similar to the ratios in catalytic converters. There is evidence for a significant correlation of PGE input and local parameters such as traffic-conditions, distance from the trafficlane, prevailing wind direction, and barriers such as vegetation or morphology.     

High frequency of extra-pair paternity in Swedish pied flycatchers revealed by allozyme electrophoresis and DNA fingerprinting

Summary We used two genetic techniques to study multiple parentage in the pied flycatcher (Ficedula hypoleuca). Allozyme electrophoresis of 131 nestlings from 22 clutches sampled in 1982 and 1987 showed that one nestling had a mismatched allele compared with its putative parents. In one additional nest the devitation from Mendelian inheritance of parental genotypes suggested extra-pair paternity. The calculated probability of detecting multiple paternity from the genetic variation at four loci was 0.115. The estimated population frequency of extra-pair fertilization (EPF) was 13%, based on two mismatches and the probability of detecting multiple paternity. The seven families (n = 38 nestlings) in the 1987 sample were also analyzed by DNA fingerprinting using the M13 and Jeffrey's 33.15 probes. Overall, 24% (n = 9) of the nestlings analyzed were genetically inconsistent with their putative father, with EPF occurring in three (43%) of the seven clutches. One nestling originated by intraspecific brood parasitism. Comparison of the two techniques using the same samples showed that allozyme electrophoresis has a resolution only 11% of that of DNA fingerprinting, close to the calculated probability of detecting multiple paternity (0.115). Both techniques suggest that extra-pair fertilization is relatively common in the Swedish populations investigated compared to the low frequency reported from a Norwegian population. Correspondence to: H.P. Gelter at the present address     

Analysis of lipid components for determining the condition of anchovy larvae,Engraulis mordax

It has been presumed that intertidal spawning by Limulus polyphemus minimizes the loss of egges to subtidal predators; however, this strategy involves considerable risks. Massive beach strandings of adults accompany seasonal spawning migrations of crabs along Cape May in Delaware Bay, (USA). At least 190000 horseshoe crabs, approximating 10% of the adult population, died from beach stranding along the New Jersey shore of Delaware Bay during the 1986 (May to June) spawning season. Abnormalities of the telson (which is used in righting behavior) were significantly more common among stranded crabs than among individuals actively spawning on the intertidal beach. The number of stranded crabs per day was not correlated with tidal height or environmental variables (wind speed, wave height) which characterized the conditions at spawning. A complex suite of factors, including the size of the available spawning population, tidal and weather conditions, and beach slope, influence the number stranded during the breeding season. Horseshoe crab stranding results in a large loss of gravid females from the population, and may represent a major input of organic matter to intertidal sandy beaches in certain regions of Delaware Bay.     

Self-organization of circadian rhythms in groups of honeybees (Apis mellifera L.)

Workers in social groups of honeybees (Apis mellifera L.) synchronize their individual free-running circadian rhythms to an overall group rhythm. By monitoring the activity of bees by recording the oxygen consumption and intragroup temperature, it is shown that the rhythm coordination is in part achieved by temperature fluctuations as an intragroup Zeitgeber. Trophallaxis was shown to have only a minor (if any) effect on circadian rhythm synchronization. A model incorporating a feed back loop between temperature and activity can plausibly explain the observed synchronization of individual rhythms in social groups as a self-organization phenomenon. Correspondence to: R.F.A. Moritz     

The two reindeer parasites,Hypoderma tarandi andCephenemyia trompe (Oestridae), have evolved similar olfactory receptor abilities to volatiles from their common host

Summary Using the linked gas chromatographical/electroantennogram (GC/EAG) technique it was revealed that the reindeer warble fly (H. tarandi) was specifically able to sense the same components from reindeer interdigital pheromone gland as the reindeer nose bot fly (C. trompe) another reindeer endoparasite. These two species belong to the same family (Oestridae), but different subfamilies, and the evolution towards an endoparasitic life cycle is thought to have been independent. The development of olfactory abilities to find reindeer from long distances is hypothesized to have taken place through convergent evolution or exists because of their common ancestry.     

Environmental conditions influence egg color of reed warblers <Emphasis Type="Italic">Acrocephalus scirpaceus</Emphasis> and their parasite,the common cuckoo <Emphasis Type="Italic">Cuculus canorus</Emphasis>

The outer layer of the eggshell in birds is in many cases covered by pigments that are assumed to be genetically determined traits with a negligible environmental component. To test the hypothesis that spring environmental conditions (i.e., temperature and rainfall) may affect bird egg pigmentation, we measured by spectrophotometry and photography egg coloration and spottiness on reed warbler (Acrocephalus scirpaceus L.) clutches parasitized by the common cuckoo (Cuculus canorus L.) collected over a period of 24 years and preserved in the Zoological Museum, Copenhagen, Denmark. In addition, we investigated whether spring environmental conditions may influence the coevolutionary relationship between the cuckoo and its host via changes in cuckoo–host egg matching. Generalized mixed models revealed that reed warbler eggs were more brilliant in those springs with a higher rainfall and tended to be bluer and greener in springs with a lower relative temperature. On the other hand, cuckoo eggs were bluer and greener in springs with a higher rainfall. Cuckoo–host egg matching in blue-greenness and spottiness was better in springs with a higher rainfall. These results provide support for the existence of an environmental component on bird egg coloration and suggest that environmental factors may potentially affect the outcome of important features of the arms race between cuckoos and reed warblers.