Breeding performance of the red-throated diver Gavia stellata in Shetland

Breeding red-throated divers Gavia stellata were studied in Shetland during 1981-1983. The overall probabilities of nest success were 0.35 in 1981 and 0.25 in 1982, as calculated by the Mayfield method. Productivity was shown to be at least 0.51 chicks fledged per breeding pair in 1981 (n = 100) and 0.36 in 1982 (n = 91), and a review of all field studies for Shetland gave a mean value of 0.45 per year (n = 1104) with no detectable trends in productivity since 1918; this was considered probably sufficient to maintain a stable population. Nests at lochs smaller than one hectare experienced the greatest hatching success. The majority of known breeding lochs wore used in three consecutive years, with a significantly greater re-use of lochs which had previously supported successful pairs. Breeding success declined with season in 1981 and 1982 largely due to reduced hatching success of late nesters, and a slight seasonal decline in egg volume was found in 1983.     

Observations on desmids from Scotland,Shetland, Cumbria and the English Midlands

Summary

Samples from bogs and lochs collected in the parish of Assynt, south — west Sutherland; loch and pool samples from Shetland; tarn samples from Cumbria and a small pool in Oadby, Leicestershire, have been examined. New desmid varieties and formae, some rare desmids and interesting observations on common desmids can be reported.     

The growth of brown trout Salmo trutta L. in northern Scottish lochs with special reference to the improvement of fisheries

This paper is based on the investigation of 173 lochs in Scotland from which a total of over 4700 brown trout were examined. Twenty-four of the lochs, all in northern Scotland, and their trout populations, were selected for detailed comparison in an attempt to identify environmental factors that might affect the growth rate of trout. The lochs probably represented the full range of main standing water habitats in the region-ranging from a saline loch in the Outer Hebrides to one in a sub-arctic environment high on the Cairngorm plateau in the Central Highlands. The study indicates that for practical purposes the growth rate of trout is negatively correlated with population density. Some suggestions for improving brown trout lochs, based on the findings of this paper, are included.     

The effects of land use upon water chemistry,particularly nutrient enrichment,in shallow lowland lakes: comparative studies of three lochs in Scotland

Three shallow, lowland lochs (lakes) in the Tayside region of Scotland, experiencing the same climatic regime, were found to be dimictic lakes showing similar clinograde oxygen distributions in summer. Land use differences in their catchments were shown to result in estimated total nutrient surface loadings from 0.3 to 32 g m^–2 a^–1 phosphorus and from 4 to 240 g m^–2 a^–1 nitrogen. The major ions in the lochs were calcium and carbonate, but with elevated sulphate levels in all three lochs and an increase in sodium, chloride and sulphate in Forfar loch, which was affected by sewage effluent. Conductivity and total alkalinity showed marked increases with greater intensity of land use, from 64 to 439 µS cm^–1 and 0.5–3 meq l^–1 Maximum winter loch concentrations of soluble reactive phosphorus ranged from 60 to just under 5 000 mg m^–3 and of inorganic nitrogen from 500 to 10500 mg m^–3. Maximum chlorophyll a ranged from 20 to 250 mg m^–3 and comparisons indicated that above winter levels of 5000 mg m^–3 N and 500 mg m^–3 P, the nutrient-chlorophyll relationships did not hold. Predictions of nutrient input, from land use categories and soil losses of N and P derived from other north temperate areas, were shown to be comparable with inputs calculated from loch measurements. Models predicting loch concentrations of phosphorus from inputs were comparable with measured concentrations, but predictions of chlorophyll and transparency became less accurate with higher nutrient levels. The lochs were mesotrophic (the Lowes), eutrophic (Balgavies) and hypertrophic (Forfar) under the several classification systems used. The implications of their nutrient status for lake management are discussed and the value of studying this unique lake series in a similar physical environment but with considerable chemical differences is considered.     

Sea trout in North Argyll Sea lochs, population, distribution and movements

Sea trout were sampled by shore seining in the sea lochs of the west coast of Scotland between 1970 and 1974, This area is of special interest because of the indentation of the coastline and the varying degree of freshwater and marine influence in the sea lochs. The majority of fish caught were in their first year after smolt migration. These post-smolts were caught mainly in May and June, after which the number of trout present was low until fish at the 'whirling' stage appeared in the catches at the end of August, continuing through to the following spring. An additional recruitment of mainly unsilvered young trout from the rivers to the sea lochs was found in the autumn. Age and sex composition of both spring and autumn recruits, and of mature fish, were investigated and compared.
A total of 3228 sea trout were tagged, with 311 recaptures. These recaptures supported the evidence from smolt trapping and beach seine catches that, in the first post-migration year, the smolts migrate from the rivers from late March to early May, they then migrate from the sea lochs in May and June and return in late summer and autumn.     

Surface nutrients,chlorophyll a and phaeopigment in some Scottish sea lochs

The distribution of several surface properties, both physical and chemical, of three Scottish sea lochs were studied during the spring phytoplankton bloom.Concentrations of nitrate, phosphate, and silicate have been determined and related to fluctuations in the freshwater input and uptake by the phytoplankton population. The ratios nitrate: phosphate and silicate: phosphate (on atom bases) in Loch Creran and Loch Linnhe were similar, but there were certain marked differences from those in Loch Etive.Nitrate, rather than phosphate, was a critical factor in the productivity of Loch Creran and Loch Linnhe. In Loch Etive the limitation of these nutrients was directly affected by the amount of fresh-water entering into the Loch.Patchiness of chlorophyll a and phaeopigments in Loch Creran and Loch Etive reflected those factors (e.g., freshwater/sea-water inflow, turbulence produced by the loch topography etc.) which affect the surface circulation in the two lochs.The delay in the development of the phytoplankton bloom in Loch Linnhe may be attributed to a poor stability of the surface layers due to low run-off.     

Performance and utilization of Northern European short-tailed breeds of sheep and their crosses in North America: a review

The five Northern European short-tailed sheep breeds present in North America are the Finnsheep, Romanov, Icelandic, Shetland and Gotland. The Finnsheep and Romanov were first imported in 1966 and 1986, respectively, for their high reproductive performance. The Shetland, Icelandic and Gotland breeds were first imported in 1980, 1985 and 2005, respectively, for the uniqueness of their physical appearance and their unique fleeces desired by fiber craftspeople. There have been no scientific studies conducted on the performance of the Shetland, Icelandic or Gotland breeds relative to other breeds of sheep in North America. However, the Shetland and Icelandic breeds have become very popular in the United States and ranked 9th and 18th, respectively, among 35 breeds of sheep for number of purebred animals registered in 2008. The performance of the Finnsheep breed in North America relative to domestic breeds has been thoroughly investigated. Compared to several domestic purebreds and crosses, sheep with Finnsheep breeding had a younger age at puberty, greater fertility to autumn mating, greater litter size, greater survival to weaning, similar growth rate, similar subcutaneous fat thickness, smaller loin muscle area and greater percentage of kidney and pelvic fat. Each 1% increase in Finnsheep breeding in ewes was associated with approximately 0.01 more lambs born per ewe lambing. In North American studies, Romanov ewes were superior to Finnsheep ewes for reproductive rate and lamb production per ewe under both autumn and spring mating. Lambs of the two breeds were similar for survival, growth and carcass traits. Romanov and Romanov-cross ewes produced fleeces that were heavily contaminated with medulated and colored fibers and were of very low commercial value. Three composite breeds containing 25% to 49% Finnsheep breeding (Polypay, Rideau Arcott and Outaouais Arcott) were developed in North America and are now more popular than the Finnsheep breed.     

A large and prolonged bloom of Karenia mikimotoi in Scottish waters in 2006

A prolonged bloom of Karenia mikimotoi was observed during 2006 in Scottish waters. This bloom is thought to be unique in the region in terms of its large spatial extent. From its first detection in the west of the country, the bloom moved clockwise around the coast eventually reaching the east coast and the Shetland Isles to the north. The bloom resulted in extensive mortalities of benthic organisms including annelids and molluscs and some species of fish. Farmed fish mortalities were absent but gill damage was reported. The availability of satellite remote sensing, phytoplankton counts from multiple sites, meteorological data and some water chemistry, as well as information on the physical characteristics of the sampling sites, provided an extensive spatial and temporal data set. Analysis of remotely sensed chlorophyll-a data from Aqua-MODIS indicated that this parameter is a useful early warning indicator of K. mikimotoi in shelf waters off the Scottish west coast, and suggested that the bloom developed in this region prior to its advection to coastal waters. An earth observation (EO) based harmful bloom classifier for K. mikimotoi recognised areas of elevated K. mikimotoi cell density but generated false positives in areas of high reflectance. Data were also used to evaluate, in Scottish waters, various hypotheses that exist to explain the formation of K. mikimotoi blooms including phototaxis, nutrient availability, cell transport and elevated water temperature. Specifically, we sought to evaluate if routinely collected environmental data (water temperature, insolation, wind strength and direction, and sea-loch aspect) could be used as a predictor of bloom magnitude near aquaculture facility locations, which typically lie within fjordic sea lochs. Path analysis was used to derive intuitive models linking environmental drivers to bloom magnitude. Once the effects of latitude such as northward water cooling were taken into account, only rainfall was a significant predictor of bloom magnitude at the sampling sites. Therefore, while the offshore development and progression of a bloom may be predicted from satellite information, it is likely that local hydrodynamic influences are crucial in determining its magnitude at coastal aquaculture sites.     

The effects of artificial enrichment upon the planktonic and benthic communities in a mesotrophic to hypertrophic loch series in lowland Scotland

Phytoplankton, submerged macrophytes, zoobenthos and zooplankton communities were studied concurrently in three lochs which progressively increased in trophic state. The phytoplankton showed a change in dominance from Bacillariophyceae (Pennales) and Desmidaceae in the mesotrophic Loch of the Lowes to Bacillariophyceae (Pennales) and Cyanobacteria in eutrophic Balgavies Loch and to Bacillariophyceae (Centrales) and Chlorophyceae in hypertrophic Forfar Loch. The Nygaard Compound phytoplankton quotient rose from 1.2 in the Lowes to 12 in Forfar. There was a decrease in number of species of submerged macrophytes, and in depth of colonisation from 5 m in the Lowes to 2 m in Forfar which was proportional to the decrease in mean transparency. Macrophyte biomass, however, increased in proportion to the concentration of total phosphorus in the lochs. There was a decrease in species of littoral zoobenthos, but an increase in density of profundal benthos from the Lowes to Forfar. Zooplankton also showed an increase in density with enrichment, accompanied by changes in dominance. Calanoida were dominant in the Lowes; Cladocera in Balgavies and Cyclopoda in Forfar. The importance of these differences in understanding the effects of progressive enrichment and to the management of the lochs is discussed.     

Shoot development and production studies of phragmites Australis (Cav.) Trin. Ex Steudel in Scottish Lochs

Studies were made on the development and production of Phragmites australis (Cav.) Trin. ex Steudel (= Phragmites communis Trin.) stands from Forfar Loch-polytrophic, Balgavies Locheutrophic and Loch of the Lowes-mesotrophic. Differences were detected in the shoot height, shoot dry weight, standing crop biomass, leaf area index, crop growth rate and net efficiency of solar energy conversion among the three lochs. Such differences were partly due to the different nutrient levels of the three locations. The percentage ratio of leaf to shoot weight, leaf area ratio, relative growth rate and net assimilation rate for the reed stands in the three lochs were also calculated and were compared with values from other study areas.     

Selection signatures in Shetland ponies

Shetland ponies were selected for numerous traits including small stature, strength, hardiness and longevity. Despite the different selection criteria, Shetland ponies are well known for their small stature. We performed a selection signature analysis including genome‐wide SNPs of 75 Shetland ponies and 76 large‐sized horses. Based upon this dataset, we identified a selection signature on equine chromosome (ECA) 1 between 103.8 Mb and 108.5 Mb. A total of 33 annotated genes are located within this interval including the IGF1R gene at 104.2 Mb and the ADAMTS17 gene at 105.4 Mb. These two genes are well known to have a major impact on body height in numerous species including humans. Homozygosity mapping in the Shetland ponies identified a region with increased homozygosity between 107.4 Mb and 108.5 Mb. None of the annotated genes in this region have so far been associated with height. Thus, we cannot exclude the possibility that the identified selection signature on ECA1 is associated with some trait other than height, for which Shetland ponies were selected.     

Growth,chlorophyll and mineral nutrient studies on phalaris arundinaceae L. in three scottish lochs

Growth, chlorophyll and mineral nutrients studies were made in Phalaris arundinaceae L. in three Scottish lochs of varying nutrient status from March to November in 1975. The maximum shoot height and shoot dry weight attained by the plants were approximately 160 cm and 4 g respectively. Seasonal changes in the chlorophyll levels in the Phalaris leaf were studied and two peaks were found, one in April and the other in June–July. Maximum chlorophyll level attained was 9 mg g^–1 leaf dry weight. The changes in the mineral levels in the root, stem, leaf and inflorescence parts of the plants from the three lochs were also assayed throughout the growing season. A total of eight mineral elements were studied, including carbon, nitrogen, phosphorus, potassium, sodium, calcium, magnesium and iron. Variations in both the mineral concentrations and their pattern of changes during the study period among the plants from the lochs were observed and discussed.     

The influence of food supply on the breeding ecology of Kittiwakes Rissa tridactyla in Shetland

We measured the breeding performance, body condition, time budgets and foraging ranges of Kittiwakes Rissa tridactyla at Sumburgh Head, Shetland, in two years of contrasting food availability. Kittiwakes in Shetland generally feed their young almost entirely on sandeels, and fisheries data indicated that stocks of sandeels in Shetland waters were at least ten times higher in 1991 than in 1990. Fledging success of Kittiwakes was nil in 1990 and 68% of eggs laid in 1991, although clutch-size and hatching success were no different between years. Post-hatching foraging trips in 1991 were of comparable duration to those recorded at other colonies in conditions of good food supply (2–3 h), while trips recorded during incubation or post-hatching in 1990 were approximately three times longer on average than at corresponding stages of the breeding season in 1991. Radio-tracking data indicated that adults generally stayed within 5 km of the colony in 1991 but flew more than 40 km from the colony on each trip in 1990. Eggs were apparently not left unattended in either year, despite the fact that this required adults to incubate for periods in excess of 44 h in 1990. The extent to which adults were able to increase trip durations, foraging ranges and incubation shift lengths between years, while maintaining hatching success, indicates the degree to which Kittiwakes are normally buffered against adverse feeding conditions during incubation. Reduced nest attendance and lower body-condition of adults post-hatching in 1990, in conjunction with complete post-hatching breeding failure, indicate that adults were beyond the limits of their buffering capacity during chick-rearing in 1990.     

The breeding biology of Black Guillemots Cepphus grylle in Shetland

The breeding biology of Black Guillemots Cepphus grylle was studied from 1982 to 1984 in Shetland, on islands lacking introduced mammalian predators. Adult survival (94%), clutch size (1.75-1.92) and breeding output (1.05-1.34 young fledged per breeding pair) were very high, indicating that conditions were relatively favourable on the islands studied. The timing of breeding varied significantly between years and was somewhat later than in other temperate parts of the range. In 1984 food was probably more readily available (possibly due to better weather conditions) in the pre-breeding period, which enabled more inexperienced birds to reach the condition threshold for breeding. It is likely that these birds tended to lay single-egg clutches in more open sites which were more susceptible to egg predation by crows. Nest-site quality and food availability were the key determinants of breeding productivity.     

Seabirds and sandeels: the conflict between exploitation and conservation in the northern North Sea

Sandeels, especiallyAmmodytes marinus are a major component of the diet of many predatory fish, seabirds and seals. The industrial fishery for sandeels is now the largest of the North Sea fisheries. A sandeel fishery in the Shetland area began in 1974 but has recently declined. This change was accompanied by dramatic declines in the breeding success of certain seabirds, particularly Arctic terns and kittiwakes. Current information on seabirds and sandeels in the Shetland area is reviewed and areas where further research is needed, highlighted. The Shetland problem illustrates the difficulties of reconciling conservation and exploitation when fundamental ecological and behavioural knowledge is lacking, and also the need to obtain further information on the ecological impact of industrial fisheries.     

A preliminary assessment of the quantities of Shetland sandeels taken by seabirds, seals, predatory fish and the industrial fishery in 1981–83

Shetland holds a very high concentration of seabirds that feed to a large extent on sandeels Ammodytes marinus . The available data allow an assessment of the quantity of sandeels consumed by seabirds each year 1981–83, and sensitivity analysis suggests that this figure is accurate to about ±30%. Only very approximate estimates of sandeel consumption by seals and by predatory fish can be made.
From 1981 to 1983 the Shetland fishery catch averaged 45,000 tonnes of sandeels, with an estimated natural consumption of 47,000 tonnes by seabirds (predominantly Guillemots Uria aalge and Fulmars Fulmarus glacialis ). Based on sensible guesses and the little data available, consumption may have been about 25,000 tonnes by predatory fish and 9,000 tonnes by seals. The figures suggest that natural mortality of the Shetland sandeel stock in 1981–83 was considerably in excess of the figure used in VPA stock assessments. Further information is required for key variables in order to permit better estimates of sandeel stock dynamics. In particular, we need better data on numbers and diets of seals in Shetland, numbers and diets of predatory fish, diets and foraging distributions of Fulmars, especially out with the chick-rearing period. In future, sandeel biomass assessments for Shetland should incorporate estimates of predation by seabirds as this is clearly an important part of total mortality for the stock.     

A comparison of Northeast Atlantic killer whale (Orcinus orca) stereotyped call repertoires

Killer whale call repertoires can provide information on social connections among groups and populations. Killer whales in Iceland and Norway exhibit similar ecology and behavior, are genetically related, and are presumed to have been in contact before the collapse of the Atlanto-Scandian herring stock in the 1960s. However, photo-identification suggests no recent movements between Iceland and Norway but regular movement between Iceland and Shetland. Acoustic recordings collected between 2005 and 2016 in Iceland, Norway, and Shetland were used to undertake a comprehensive comparison of call repertoires of Northeast Atlantic killer whales. Measurements of time and frequency parameters of calls from Iceland (n = 4,037) and Norway (n = 1,715) largely overlapped in distribution, and a discriminant function analysis had low correct classification rate. No call type matches were confirmed between Iceland and Norway or Shetland and Norway. Three call types matched between Iceland and Shetland. Therefore, this study suggests overall similarities in time and frequency parameters but some divergence in call type repertoires. This argues against presumed past contact between Icelandic and Norwegian killer whales and suggests that they may not have been one completely mixed population.     

Breeding bird communities and environmental variable correlates of Scottish peatland wetlands

The majority of lochs and water courses in an area of northern Scotland were visited during July 1988. Breeding waterfowl and details of environmental variables were recorded for each site and subjected to multivariate classification techniques. Non-hierarchical classification identified seven habitat types on the basis of environmental parameters. These corresponded well with, and further sub-divided, categorisation using conventional trophic-level habitat type classifications. A hierarchical approach, using TWINSPAN, classified twelve waterfowl groupings based on the presence of indicator species. This approach identified characteristic community types and groupings with high diversity and hence conservation importance. Correspondence between habitat classifications and waterfowl communities was reasonable, but failure to identify key features of wetland complexity was probably the reason for the inability to identify clear relationships. Induction analysis was used to show that waterfowl species with the most restricted distributions characterised the main groupings, with Black-throated Diver and Common Scoter showing preferences for mesotrophic/eutrophic waters with islands, where peaty waters drain onto base-rich sandy substrates. Greylag Geese occurred on large acidic oligotrophic lochs and Wigeon on base-rich streams. The need for catchment-wide site-safeguard and management programmes to safeguard the wetlands of greatest significance is discussed.     

Allometric and morphological characteristics of Tonicella marmorea (Fabricius, 1780) populations (Mollusca: Polyplacophora: Ischnochitonidae)

Allometric and morphological characteristics of population samples of Tonicella marmorea from three sea lochs on the west coast of Scotland are described. The suitability of allometric relationships as taxonomic criteria are investigated by statistical comparisons of various regression constants, scatter diagrams and comparisons of curvature indices. Morphological characteristics such as ctenidia number and numbers of notches in the head and tail valves proved too variable to be regarded as diagnostic but they are useful taxonomic indicators. The need for all taxonomic characteristics to be derived from population samples is stressed and the use of valve and girdle sculpturing together with radula structure is emphasized.     

Heart rate and heart rate variability in pregnant warmblood and Shetland mares as well as their fetuses

Heart rate (HR) is an important parameter of fetal well-being. In horses, HR and heart rate variability (HRV) can be determined by fetomaternal electrocardiography (ECG) from mid-pregnancy to foaling. Normal values for physiological parameters in larger breeds are often used as reference values in ponies. However, HR increases with decreasing size of the animal and in ponies is higher than in warmblood horses. It is not known if fetal HR is affected by breed and if values obtained in larger breeds can be used to assess Shetland fetuses. We have determined fetomaternal beat-to-beat (RR) interval (inversely correlated to HR) and HRV in warmblood (n=6) and Shetland pregnancies (n=7) at days 280 and 300 of gestation by ECG. Maternal RR interval was lower in pony than in warmblood mares (day 280: Shetland: 958±110, warmblood: 1489±126ms, p<0.01) The SDRR (standard deviation of RR interval) and the RMSSD (root mean square of successive RR differences) did not differ between breeds at any time. Also RR interval as well as HRV did not differ between warmblood and pony fetuses (RR interval day 280: Shetland: 606±39, warmblood: 589±38ms). In conclusion, although maternal RR interval is clearly higher in Shetland than in warmblood mares, fetal RR interval in the two breeds is on the same level.