A New Naked Jawless Vertebrate From The Middle Devonian Of Scotland

A new jawless vertebrate, Achanarella trewini gen. et sp. nov., is described from some recently discovered, relatively well–preserved specimens from the Achanarras fish bed at Achanarras Quarry, northern Scotland. The Achanarras fish bed is of Middle Devonian (Eifelian) age. Achanarella is a torpedo–shaped jawless vertebrate with a strongly hypocercal tail and well–developed anal fin. It has at least 13 branchial openings with possibly more than 20. It is scaleless. Achanarella compares well with the Frasnian Euphaneropidae of the Escuminac Formation in Quebec, Canada, and Cornovichthys blaauweni Newman and Trewin, 2001, also from the Achanarras fish bed. It differs from these forms mainly in being extremely long and thin and having a very small head compared with body length.     

Middle Devonian (Eifelian) spores from a fluvial dominated lake margin in the Orcadian Basin,Scotland

The stratigraphic distribution of Mid Devonian spores is recorded from the Easter Town Burn Siltstone Member. A significant inception within the section is Ancyrospora grandispinosa. This indicates that the Easter Town Siltstone Member is a correlative of the basin-wide Achanarras lake horizon and not pre-Achanarras as hitherto assumed. It is also a correlative of the local nodular limestones. These limestones represent areas without significant clastic input, while the Easter Town Burn Siltstone Member is the point at which significant fluvial input entered an embayment at the margin of the Orcadian lake. This gives a clastic dominated Achanarras equivalent. A new species of Verrucosisporites (V. loboziakii) is described.     

A NEW DIPNOAN FISH FROM THE MIDDLE DEVONIAN (EIFELIAN) OF SCOTLAND

Abstract:  A new dipnoan fish, Pinnalongus saxoni gen. et sp. nov., is described from a suite of recently discovered specimens from Caithness and East Sutherland, northern Scotland. The stratum where Pinnalongus occurs is within the middle Eifelian of the Middle Devonian. Pinnalongus has a skull roof consisting of a mosaic of small bones at the anterior end, a feature more typically found in Early Devonian dipnoans. The posterior part of the skull roof is more typical of later advanced Middle Devonian dipnoans with the B-bone separating the I-bones. The postcranial body is now considered not to be so important with respect to the classification of dipnoans as originally proposed by Dollo in 1895, who thought there was an evolutionary transformation series. Nevertheless, the postcranial body of Pinnalongus has more in common with later Middle and Late Devonian dipnoans such as Scaumenacia , with a very long second dorsal fin. Based on the skull morphology, Pinnalongus is most closely related to Tarachomylax from the Lower Devonian of Severnaya Zemlya, Russia. Pinnalongus represents the earliest known complete articulated dipnoan with tooth plates.     

The management and restoration of damaged blanket bog in the north of Scotland

Summary

The blanket bogs of Caithness and Sutherland are the finest examples of their type in the world. Restricted to a few parts of the world where cool, oceanic climatic conditions prevail, Britain holds approximately 13% of the total global resource of blanket bog, of which the bogs of Caithness and Sutherland form the largest and most intact area. In recent times, extensive areas of the peatlands of Caithness and Sutherland have been damaged – principally through drainage and forestry. In 1994, the Royal Society for the Protection of Birds (RSPB) purchased Forsinard Estate in the heart of the peatlands as part of a EU LIFE funded project on blanket bog conservation. In partnership with Scottish Natural Heritage and Caithness and Sutherland Enterprise, this four year RSPB led project promoted a number of initiatives on awareness raising and ecotourism as well as a range of practical demonstrations on restoring damaged blanket bog. More recently, a follow up LIFE Peatlands Project was launched in 2001 where RSPB extended the partnership to include SNH, Forest Enterprise, Plantlife and the Forestry Commission. This paper gives an over-view of the partnership approach to the management and restoration of damaged blanket bog in Caithness and Sutherland.     

Nest Records of the Swallow

Daytime attendance of Guillemots, Razorbills, Kittiwakes and Fulmars at colonies in east Caithness was monitored by time-lapse photography over the winters of 1982/83, 1983/84 and 1984185. Fulmars frequented the colonies over a large part of each non-breeding period but were absent for extended spells in mid-winter. Guillemot visits were infrequent and usually involved relatively small numbers. They became more frequent in February in 1984 and 1985, but not in 1983, the year of a large wreck of auks on the east coast of Britain. Razorbills and Kittiwakes were absent throughout autumn and winter and re-appeared in late February or early March. The low level of winter attendance by auks, which contrasts with reports from colonies elsewhere, was probably because few adults wintered within easy reach of the Caithness colonies.     

Factors affecting fish diversity on a temperate reef: the fish assemblage of Palos Verdes Point, 1974–1981

Synopsis We conducted underwater fish assemblage surveys, benthic quinaldine sampling, and ichthyoplankton collections over high and low relief reefs at Palos Verdes Point, California from 1974 through 1981. Seventy-three species (adults and larvae) were collected or observed at Palos Verdes. Of the 24 most abundant species, 8 showed significant abundance trends correlated with changes in sea surface temperatures; four increasing, and four decreasing. Two taxa occurred predominantly in the kelp canopy, while seven others were distributed at least 20% of the time between the canopy and the bottom. There was little significant change in the Palos Verdes benthic fish assemblage with development of the kelp bed. Only the kelp bass, Paralabrax clathratus, showed a significant increase in abundance that correlated with the kelp bed formation. Similarly, we did not note an increase in juvenile fish during this period. In general, we suggest that the presence or absence of kelp has little effect on the abundance of most fish species in a high relief environment. Analysis of our data and that of other studies indicate that kelp bed fish assemblages within the Southern California Bight vary in a south-north direction. The Palos Verdes Point kelp bed appears to be more productive than those nearer the limit of the Bight, but was consistently lower in both fish abundance and diversity then the nearby breakwater at King Harbor. This difference has been maintained even though changes in the species structure at King Harbor has altered sufficiently since 1976 for the two formerly distinct assemblages to be significantly concordant.     

Epiphyte response to in situ manipulation of nutrient availability and fish presence in a <Emphasis Type="Italic">Posidonia oceanica</Emphasis> (L.) Delile meadow

This study examined the effects of the configuration of wood structures on the use of local autumn and winter habitats by fish in a remeandering reach of a large lowland river. Fish diversity was higher at the simple wood-structure (SWS) and the log-jam (LJ) sites than at the no-wood (NW) sites during both seasons. In particular, the diversity at the LJ sites was higher than that at the SWS sites during the winter. The abundance of the four dominant fish species was generally higher at the LJ sites than at the NW sites during both seasons. The SWS and LJ sites were characterized by greater depths, finer bed materials, and more diverse flow conditions during the autumn. During the winter, the LJ sites were characterized by slower currents and finer bed materials. These habitat features satisfied the various habitat requirements of the fish observed in our study reach; during the autumn, areas with fast and slow currents were favorable for juvenile salmon, silt and sand bed materials for lamprey, and deep areas for one species of goby, while slow currents were critical in the winter for abovementioned fish species. Engineered log jams were also effective in supporting the colonization of fish during both seasons. These findings suggest that a larger and more complex wood structure, particularly log jams, plays important roles in creating local habitats suitable for various fish species during the autumn and winter and in preserving fish abundance and diversity in large lowland rivers.     

Patchy bed disturbance and fish predation independently influence the distribution of stream invertebrates and algae

1. The identification of factors determining the patchy distribution of organisms in space and time is a central concern of ecology. Predation and abiotic disturbance are both well-known drivers of this patchiness, but their interplay is still poorly understood, especially for communities dominated by mobile organisms in frequently disturbed ecosystems. 2. We investigated the separate and interactive influences of bed disturbance by floods and predation by fish on the benthic community in a flood-prone stream. Electric fields excluded fish predators from half of 48 stream bed patches (area 0·49 m(2) ) with contrasting disturbance treatments. Three types of bed disturbance were created by either scouring or filling patches to a depth of 15-20 cm or by leaving the patches undisturbed, thus mimicking the mosaic of scour and fill caused by a moderate flood. Benthic invertebrates and algae were sampled repeatedly until 57 days after the disturbance. 3. Disturbance influenced all ten investigated biological response variables, whereas predation affected four variables. Averaged across time, invertebrate taxon richness and total abundance were highest in stable patches. Algal biomass and densities of five of the seven most common invertebrate taxa (most of which were highly mobile) were higher in fill than in scour patches, whereas two taxa were more abundant in scour and stable than in fill patches. Furthermore, two common invertebrate grazers were more abundant and algal biomass tended to be reduced in fish exclusion patches, suggesting a patch-scale trophic cascade from fish to algae. 4. Our results highlight the importance of patchy physical disturbance for the microdistribution of mobile stream organisms and indicate a notable, but less prevalent, influence of fish predation at the patch scale in this frequently disturbed environment. Disturbance and predation treatments interacted only once, suggesting that the observed predation effects were largely independent of local bed disturbance patterns.     

Dietary fish oil administration retards the development of hypertension and influences vascular neuroeffector function in the stroke prone spontaneously hypertensive rat (SHRSP).

An influence of fish oils (rich in eicosapentaenoic acid, EPA) in modulating (a) the development of hypertension in the stroke prone spontaneously hypertensive rat (SHRSP) and (b) vascular neuroeffector mechanisms in the SHRSP was explored. Rats (SHRSP) were placed on a series of diets for a period of 13 weeks from 4 weeks of age. The fatty acid composition of the diets was derived from fish oil, olive oil, safflower oil or beef fat. After 13 weeks, rats fed diets containing fish oil (at a total dietary fat level of either 5% or 15%) had mean blood pressures approximately 20-25 mmHg lower than other SHRSP rats maintained on diets containing either olive oil, safflower oil or beef fat. The dietary schedules providing fish oil depressed the contractile responses mediated by sympathetic nerve stimulation in the mesenteric vascular bed preparation. The results suggest that the n-3 polyunsaturated fatty acids retard the development of hypertension in the SHRSP rat and modulate the contractile responses of blood vessels mediated by sympathetic nerves in the isolated perfused mesenteric vascular bed preparation.     

A hybrid zone comprising staggered chromosomal clines in the house mouse (Mus musculus domesticus).

In the vicinity of John o'Groats (Caithness, Scotland) there is a small karyotypic race of the house mouse (Mus musculus domesticus) characterized by a diploid number of 32 chromosomes, including the metacentrics 4.10, 9.12, 6.13 and 11.14. This race forms a hybrid zone with the standard British race (fully acrocentric chromosomes, 2n = 40). Although hybrid zones normally consist of several (or many) narrow character clines at the same position, this zone is unusual in that the chromosomal clines do not coincide. The cline for arm combination 11.14 is staggered relative to the 6.13 cline and both are separate from the clines for 4.10 and 9.12 (which may or may not coincide). A variety of explanations for the structure of the hybrid zone are discussed. It is possible that this may be a case of 'zonal raciation'.     

Floating-leaved and emergent vegetation as habitat for fishes in a eutrophic temperate lake without submerged vegetation

Although submerged vegetation is considered to be the most suitable refuge against predators and form of foraging habitat for small fishes, submerged plants are often scarce or lacking in turbid eutrophic lakes. To evaluate emergent (Zizania latifolia) and floating-leaved (Nelumbo nucifera) vegetation as refuge areas against predators and as foraging habitats for small fishes, we investigated the fauna, abundance, and size distribution of the fish community as well as the abundance of possible prey for small fishes in beds of each vegetation type in a eutrophic shallow lake: Lake Teganuma in Japan. The leaves and stems of N. nucifera occupied an area 4.2 times larger than that of Z. latifolia. The high coverage of the water surface with plants most likely induced the hypoxia found in the N. nucifera bed. The diversity of small fishes was greater in the Z. latifolia bed with piscivorous fish than in the N. nucifera bed without piscivorous fish. The diversity of fish species in the vegetation was enhanced when there was an increased diversity of possible food sources rather than an absence of predators. Some aquatic insects of the same species had a much lower δ¹³C signature at hypoxic locations than at less hypoxic locations in the N. nucifera bed. Such site differences within a bed were not observed in the organisms caught in the Z. latifolia bed. The insects in hypoxic zones with a δ¹³C signature lower than ?30 ‰ were more depleted in ¹³C than the surface sediment or attached algae, suggesting that the larvae in the hypoxic zones incorporated the organic materials generated by methane-oxidizing bacteria. We can therefore conclude that floating-leaved vegetation, especially a N. nucifera bed, is not suitable as a replacement for submerged vegetation because of its potential to induce hypoxia, which can decrease the diversity of the fish fauna.     

Response of Benthic Protozoa and Thraustochytrid Protists to Fish Farm Impact in Seagrass (Posidonia oceanica) and Soft-Bottom Sediments

We investigated the impact of fish farm biodeposition on benthic bacteria, thraustochytrid protists, and heterotrophic protozoa (nanoflagellates and ciliates) in an oligotrophic area of the Mediterranean Sea. The fish farm impact was investigated both on a seagrass (Posidonia oceanica) bed and on soft bottom sediments. In both systems, sediment samples were collected with a multicontrol sampling strategy (i.e., beneath the fish farm and at three control sites per system). The uneaten food pellets supplied to the fish determined the accumulation of sediment organic matter and the enhancement of protein content in impacted sediments (both seagrass bed and soft sediments). In both systems, the abundance and biomass of heterotrophic protists increased significantly beneath the fish farm, but the structure of the protist assemblages responded differently in vegetated and unvegetated sediments. Thraustochytrid abundance increased significantly in impacted seagrass. These results provide evidence that the structure of protist assemblages respond significantly to fish farm biodeposition and indicate that the monitoring of these benthic components provides complementary information for the assessment of the fish farm impact on the benthic systems.     

Quantifying the direct and indirect effects of flow‐related disturbance on stream fish assemblages

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On some cestodes parasitizing freshwater fish in Italy.

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Taphonomy and origin of an accumulate of soft-bodied cephalopods in the Oxford Clay Formation (Jurassic, England)

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The Species Composition and Distribution of Fish and Prawn in the Bed of the Lower Amur River

Russian Journal of Marine Biology - The distribution of fish and prawn in the bed of the lower Amur River (within 40–960 km from the mouth) is described based on the results of a beam-trawl...     

Length‐weight relationships of 4 fish species from a seagrass Zostera marina bed in Koje Bay,Korea

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