Vegetation and land use in the Loch Lomond catchment

The Loch Lomond catchment lies across the boundary between the Lowlands and Highlands of Scotland, and its vegetation and land-use are influenced by the environmental contrasts which occur on either side of the Highland Boundary Fault. In the northern part of the catchment area elevations exceed 800 metres, and thus there is an altitudinal zonation component to vegetation and land-use patterns.The role of man has been profound in modifying natural vegetation, and recent land-utilisation is reviewed. Changing human and environmental circumstances have a significant effect on vegetation and land-use, and these factors are evaluated. Though natural and semi-natural vegetation occupies only a small fraction of the catchment, its conservation importance is considerable. In terms of scenic and heritage resources, the whole area has international significance and the Loch Lomond catchment requires special protection and management.     

A comparative assessment of temporal variation in diet of powan, Coregonus lavaretus (L.), from Loch Lomond and Loch Eck, Scotland, U.K.

Stomach contents of powan caught throughout the year from Loch Lomond and Loch Eck were examined. Adult powan in Loch Lomond fed mainly on planktonic Cladocera, switching to benthic food during December-April. Bosmina coregoni was the principal planktonic food with Daphnia hyalina an important late summer and autumn prey. Loch Eck powan fed throughout the year on chironomid larvae and Pisidium spp. from the benthos and ingested large amounts of non-food material. Mean dry weights of food in stomachs were correlated with water temperature in Loch Lomond but not in Loch Eck and were higher in powan from Loch Eck over most of the year.     

Zooplankton in Loch Lomond: perspectives,predation and powan

Published and unpublished accounts of the zooplankton community of Loch Lomond are reviewed. Loch Lomond's zooplankton community is unique amongst those of Scotland's other large lochs. Holopedium gibberum appeared in Loch Lomond in the years between the studies of Slack & Hamilton in the 1950s and zooplankton surveys in the late 1970s.The annual cycles of Eudiaptomus gracilis, Cyclops strenuus abyssorum and Mesocyclops leuckarti are described for the mid basin of Loch Lomond. E. gracilis overwinter mainly as adult with variable egg production during their lifespan of 5–8 months. The cyclopoid copepods have variable life history characteristics. C. str. abyssorum produce a single generation per year, overwinter by means of resting eggs and a small population of planktonic adults, while M. leuckarti is present in the plankton throughout the year, but in low numbers during winter.Zooplankton populations in Loch Lomond are predated by the diverse fish community which includes a facultative planktivore in the powan, Coregonus lavaretus. Powan feed heavily on zooplankton from late spring until late autumn. Powan display selectivity in the prey species taken, in the size distribution and morph types taken within prey species. Zooplankton species, morphs and forms in Loch Lomond tend to reflect this predation.Zoology Department, University of St. AndrewsZoology Department, University of St. Andrews     

Has habitat heterogeneity promoted phenotypic and ecological sub‐structuring among a Coregonus lavaretus population in a large Scottish lake?

Differences in stable‐isotope values, morphology and ecology in whitefish Coregonus lavaretus were investigated between the three basins of Loch Lomond. The results are discussed with reference to a genetic investigation to elucidate any substructuring or spawning site fidelity. Foraging fidelity between basins of Loch Lomond was indicated by δ¹³C and δ¹⁵N values of C. lavaretus muscle tissue. There was, however, no evidence of the existence of sympatric morphs in the C. lavaretus population. A previous report of two C. lavaretus‘species’ in Loch Lomond probably reflects natural variation between individuals within a single mixed population.     

Continuous variation in the pattern of marine v. freshwater foraging in brown trout Salmo trutta L. from Loch Lomond, Scotland

Carbon stable-isotope analysis showed that individual brown trout Salmo trutta in Loch Lomond adopted strategies intermediate to that of freshwater residency or anadromy, suggesting either repeated movement between freshwater and marine environments, or estuarine residency. Carbon stable-isotope (δ¹³C) values from Loch Lomond brown trout muscle tissue ranged from those indicative of assimilation of purely freshwater-derived carbon to those reflecting significant utilization of marine-derived carbon. A single isotope, two-source mixing model indicated that, on average, marine C made a 33% contribution to the muscle tissue C of Loch Lomond brown trout. Nitrogen stable isotope, δ¹⁵N, but not δ¹³C was correlated with fork length suggesting that larger fish were feeding at a higher trophic level but that marine feeding was not indicated by larger body size. These results are discussed with reference to migration patterns in other species.     

A seasonal and ecological study of the phytoplankton of Loch Lomond

The seasonal succession of phytoplankton in Loch Lomond has been studied both quantitatively and from observations on net plankton. From a qualitative investigation of net phytoplankton Loch Lomond may be described as diatom-desmid in nature although from the quantitative studies the general domination of the population by diatoms becomes clear. During the vernal phytoplankton increase diatoms contributed more than 90% of the population throughout the loch. The bulk of the phytoplankton production occurred in the southern region, where the standing crop was considerably greater throughout the year than in other regions of the loch.Patterns of seasonal succession are described for all species which make an important contribution to the productivity of the loch and the observed successions related to measured physical and chemical changes in the water. Explanations are put forward to account for the absence of a second (autumnal) pulse ofMelosira in Loch Lomond. The appearance ofAnabaena circinalis is a possible indication of the changing trophic status of the southern region of the loch.     

The age and growth of perch (Perca fluviatilis L.) in two Scottish lochs

This study is concerned with the age and growth of perch ( Perca fluviatilis L. ) in two contrasting Scottish lochs-the Dubh Lochan and Loch Lomond. Age and back-calculated growth were determined from annual rings in the opercular bones, and during the 2-year project 470 perch from the Dubh Lochan and 796 from Loch Lomond were examined. Growth in length in the two lochs, though similar for the first 2 years, differed thereafter, the average length at 8 years in the Dubh Lochan being less than 15 cm, that in Loch Lomond more than 23 cm at the same age. In neither locality did the growth of perch follow the Von Bertalanffy growth formula. Reasons for differential growth rates are discussed and comparisons made with the growth of perch in other waters in Europe and North America.     

The importance of Loch Lomond National Nature Reserve for Fish

Loch Lomond NNR with 19 fish species is ranked top in fish conservation value of 235 NNRs in Great Britain due to species diversity, presence of rare species and unusual forms and combinations.     

Freshwater and wetland plant communities of Loch Lomond

Information on the aquatic and wetland vegetation of Loch Lomond, Scotland, is summarised for the period 1957–90. Aquatic macrophyte growth is estimated to occupy about 1% of the loch's total surface area, being limited to the 0–10 m euphotic zone, and probably excluded from much of this area by wave disturbance and unsuitable substrates. Aquatic vegetation is however abundant in sheltered bays and less-exposed shorelines, particularly in the South Basin of the loch. Although Littorella uniflora (L.) Aschers is the commonest, ubiquitous, submerged plant of the loch, three separate euhydrophyte communities have been identified within the loch. One of these is characterised by abundant stands of Elodea canadensis Michx., which appears to have invaded Loch Lomond some time between 1967–88, and has rapidly spread throughout the loch.     

Assessment of eutrophication in Loch Lomond by desk analysis

Phosphorus and chlorophyll a levels were predicted for Loch Lomond from desk-derived P loss coefficients and flushing rates related according to existing eutrophication models. These were in close keeping with measured values.     

The winter diet and parasitic fauna of a population of Rednecked Wallabies Macropus rufogriseus recently introduced to Scotland

Although the Red-necked Wallaby is native to south-east Australia and Tasmania, at least four colonies have become established in the UK and two of these still survive. Here we provide the first account of a colony that became established following the deliberate release of four individuals to an island in Loch Lomond, Scotland in 1975. Data presented here show that this population is well established, having grown to at least 26 individuals by 1992. Wallaby diet in winter (a critical period for survival in the other remaining UK population) is composed of Blaeberry Vaccinium myrtillus and Heather Calluna vulgaris, each making up 35% of the plant fragments by occurrence in faecal pellets, with grasses making up a further 13%. Two species of parasitic coccidian protozoa and four species of strongyle nematode were found in faecal samples from this colony but the infection rate was low compared with what limited published data exist for this species. The possible reasons for the success of this most northerly of the UK wallaby populations are its isolation, the maritime climate and vegetation structure of the inhabited area.     

Empirical Modelling of the Population Dynamics of a Small Population of the Threespine Stickleback, <Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis>

Synopsis We estimated the abundance of a small population of threespine stickleback, Gasterosteus aculeatus, by mark-recapture over a 21 year period. Length-frequency analysis showed that the population in October consisted almost entirely of young-of-the-year. The per capita annual rate of increase was inversely related to abundance in October. Time series analysis suggested the presence of a cycle of abundance with a period of about 6 years. There was a significant inverse relationship between abundance in year t and in year t + 3. A simple, empirical, deterministic model based on this inverse relationship and run for 100 years predicted that population abundance showed damped oscillations leading to a stable abundance. When a stochastic component was added to the model, seven of 10 runs included a component with a period of about 6 years. These simulations suggest that the dynamics of this population are driven by an interaction between a deterministic (density-dependent) component and a stochastic component. We compare these results with time series of abundance of threespine stickleback obtained from the Thames Estuary in south-east England and Loch Lomond in Scotland.     

The ecology of lampreys (Petromyzonidae) in the Loch Lomond area

All three lamprey species occurring in western Europe are found in the Loch Lomond area: Sea Lamprey Petromyzon marinus L., River Lamprey Lampetra fluviatilis (L.) and Brook Lamprey Lampetra planeri (Bloch). There are major differences in ecology among the three species and in each some features seem to be unique to the Lomond populations. Available data on the ecology of the three species in the area are presented and existing threats reviewed. Future research and conservation requirements are outlined.     

Environmental change and the chemical record in Loch Lomond sediments

The chemical record in Loch Lomond sediments deposited since the end of the last Ice Age provides evidence of the Flandrian marine transgression some 5500–7000 ¹⁴C years B.P., sedimentation rates and the influence of man's local activities, environmental pollution and its sources since the onset of the Industrial Revolution, and of elemental mobility linked with the reduction-diffusion-oxidation cycle of early sedimentary diagenesis. Information derived from vertical profiles of halogen elements bromine and iodine, radionuclides ¹⁴C and ²¹⁰Pb, heavy metals lead, zinc, and cadmium, stable lead isotopes ²⁰⁶Pb and ²⁰⁷Pb, and redox-sensitive elements manganese, iron and arsenic is reviewed and assessed.     

'Bald spot' disease in powan Coregonus lavaretus (L.)

The stocks of powan Coregonus lavaretus (L.) in Loch Lomond (Scotland) were affected by an acute no-ulcerative inflammatory lesion in the centre of the head, at the same time as ulcerative dermal necrosis (U.D.N.) became apparent in salmon in the Loch. The numbers of powan were very great at the time, and fish were of poor quality and frequently fungus-infected. No pathogen was isolated from the lesions which rarely contained fungus, and were histologically very different from the lesions of U.D.N. in salmon. Its disappearance by the following year, coincided with a marked improvement in quality of the fish.     

The genetic relationships of the coregonid fishes of Britain and Ireland indicated by electrophoretic analysis of tissue proteins

The electrophoretic patterns of the general proteins, esterases, creatine kinase and phosphoglucomutase of white muscle from Lough Neagh pollan, Lough Erne pollan, Lake Bala gwyniad, Loch Lomond powan, Haweswater schelly and Bassenthwaite vendace are consistently of three types. It is therefore suggested that the coregonids examined are three distinct species: the pollans; gwyniad, powan and schelly; vendace. Vendace is genetically closer to the gwyniad group than to the pollans.     

Morphological abnormalities in a population of Lampetra planeri,with a short review of petromyzontid teratologies

Reported here are several deviations (n = 15; 1·96%) from typical morphology in a large sample (n = 767) of European brook lamprey Lampetra planeri from a single population in the Loch Lomond catchment; this includes one specimen bearing a true anal fin. A brief review of petromyzontid teratology is provided.     

The physico-Chemical limnology of Loch Lomond

Loch Lomond, the largest freshwater lake in Britain, is physically divided into a number of distinct basins by geological structures. The northern part of the loch is long, narrow and deep whilst the southern area is broad and shallow with many islands scattered throughout it.The water chemistry of the loch is dictated by the geology of catchment and the quality of the rivers flowing into it. The two major rivers, the Falloch and the Endrick Water, are both of good quality with low nutrient content. Consequently, the loch is regarded as oligotrophic, though the southern area verges towards being mesotrophic.     

A PRELIMINARY TAXONOMIC REVISION OF THE BRITISH WHITEFISH WITH ESPECIAL REFERENCE TO THE GWYNIAD OF LLYN TEGID (BALA)

The paper deals with a biometrical analysis of forty-one specimens of the Gwyniad, Coregonus clupeoides pennantii (Cuv. et Val.) of Bala Lake, (Llyn Tegid) North Wales. Tho Gwyniad shows the greatest relationship to the continental coregonids Coregonus lavaretus . It is proposed that the taxonomy of the British whitefishes be revised and that the Gwyniad be classified as Coregonus lavaretus pennantii (Cuv. et Val.). Similarly, it is proposed that the Powan of Loch Lomond be classified as Coregonus lavaretus clupeoides Lacépède. The classification of the Schelly from the English Lake District needs further investigation.     

Evidence of a recent decline in river lamprey Lampetra fluviatilis parasitism of a nationally rare whitefish Coregonus lavaretus: is there a diamond in the ruffe Gymnocephalus cernuus?

Lamprey‐induced scarring of the nationally rare Coregonus lavaretus, a known host of a freshwater‐resident population of European river lamprey Lampetra fluviatilis, was found to have declined precipitously since the establishment of several non‐native fishes in Loch Lomond. Evidence presented in this study points to the possibility that L. fluviatilis in this lake may have altered its trophic ecology in response to the negative impact that non‐native species, in particular ruffe Gymnocephalus cernuus, have had on their favoured host.