Primary structure of otter (Lutra lutra L.) myoglobin. II. Pepsin peptides of trypsin hydrolysate. Reconstruction of the polypeptide chain of the otter myoglobin globin component

13 peptic peptides have been isolated from the insoluble (at pH 5.0) fraction of the tryptic hydrolysate of main chromatographic component of otter myoglobin and their amino acid composition and N-terminal amino acid sequences have been determined. The isolated peptides contain in total 40 amino acid residues. The results obtained, along with those on tryptic peptides and the comparison with homologous portions of myoglobins of the known primary structure, allowed reconstructing the complete amino acid sequence of otter myoglobin.     

The otter (Lutra lutra L.) in Spain

In a survey of Spain during June 1981, signs of otters were found at seventy (40%) of the 176 stations investigated. Otters were mainly concentrated in the mountainous north and north-west and in the plains and mountains of the south-west. Water pollution appears to be an important limiting factor in some areas.     

The otter (Lutra lutra L.) in western France

In a survey of western France during October-November 1980, signs of otters were found at 46 (15%) of the 315 sites investigated. Otters were largely restricted to four areas, three of these being in the uplands (of Brittany, the Massif Central and the Pyrenees) and one in the coastal lowlands (of the Landes-Gironde). The average number of signs found per successful site was 1 6, significantly lower than for Scodand and Ireland but similar to the figure for England. The percentage of positive sites and the scattered nature of the signs in western France was also broadly comparable witJi the English situation. This is surprising since most of the factors which adversely affect otters appear to be less oppressive there dian in England. Only water pollution is noticeably more extreme and this seems to offer the best, overall explanation for the nature of the decline in the area studied.     

Trophic diversity of the otter (Lutra lutra L.) in temperate and Mediterranean freshwater habitats

Aim To analyse the geographical patterns in the composition and diversity of otter's (Lutra lutra L.) diet and their relationship with climatic characteristics. Location European freshwater habitats under Mediterranean and temperate climatic regimes. Methods Thirty‐seven otter diet studies were reviewed, twenty‐one from temperate and sixteen from Mediterranean areas. All studies were based on spraint analysis and their results expressed as relative frequency of occurrence of seven main prey categories. Principal Component Analysis was performed to extract the main gradients of diet composition. Pearson's correlation and t‐tests were used to assess the relationship between diet characteristics (composition, diversity and taxonomic richness) and geographical and climatic variables. Results A clear latitudinal gradient in diet composition was observed. Otter diet was more diverse and featured more prey classes in southern localities, while the species was more piscivorous towards the north, where it predated upon a higher number of fish families. This pattern was similar when temperate and Mediterranean localities of Europe were compared. Mediterranean otters behaved as more generalist predators than temperate ones, relying less on fish, and more on aquatic invertebrates and reptiles. Main conclusions Geographical differences in otter feeding ecology in Europe seem to be related with the two contrasted climatic conditions affecting prey populations. The otter can act as a highly specialized piscivorous predator in temperate freshwater ecosystems, which do not suffer a dry season and have a comparatively stable water regime compared to Mediterranean ones. However, the unpredictable prey availability in Mediterranean areas, affected by strong spatial and temporal water shortages, favours a diversification of the otter's diet.     

Mitochondrial genetic diversity and structure of the European otter (Lutra lutra) in Britain

The European otter (Lutra lutra) is a focus for conservation efforts throughout Europe due to a population decline in recent decades and because of its importance as a biological indicator of the health of rivers and waterways. The aim of this study was to aid the conservation of this species by adding genetic information from samples originating in the United Kingdom (UK), to help build up a picture of the phylogeographic structure of the European otter throughout Europe. This was done by a comparison of 299 base pairs of the mitochondrial DNA control region. Four haplotypes were identified in the UK, one of which has not been found outside the west of the UK in the wild, and one of which was unique. Populations in the UK, and in particular the west were shown to have a higher haplotype diversity than previously found for the European otter in Europe (h = 0.7338 for the 58 UK otters sampled in this study) and an overall nucleotide diversity of π = 0.003. The western UK population was shown to have a high level of genetic distinctiveness. We discuss possible contributory population processes, the importance of the western UK population for the future conservation of the species and comment on future conservation strategies.     

The status of the otter (L. lutra L.) in Britain in 1977

Two surveys based on otter hunt records showed a 40% fall in the otter population 1957–1967, arrested and in places reversed by 1971 save in the central Midlands. The possible causes of that decline and of its apparent continuation in the Midlands are discussed. While accepting those two surveys most conservationists have since then refused to accept or consider any evidence from otter hunts: the writer does not. Reports of the presence of otters by naturalists are shown plotted on a map and suggest that they are present in sufficient numbers and at a sufficient density over the whole of Great Britain, save the central Midlands, to ensure a recovery to the pre-1960 density. Positive evidence found by hunts in a number of places in which naturalists had found none suggest that negative evidence should be accepted with caution.     

Carnivora: the primary structure of the common otter (Lutra lutra, Mustelidae) hemoglobin

The hemoglobin of the Common Otter (Lutra lutra, Carnivora) contains only one component. The complete primary structures of the alpha- and beta-chains are presented. They were separated by high-performance liquid chromatography and the sequences determined by automatic liquid and gas-phase Edman degradation of the chains and their tryptic peptides. The alpha-chains show 18 and the beta-chains 13 substitutions compared to human alpha- and beta-chains, respectively. In the alpha-chains one heme- and two alpha 1/beta 1-contacts are exchanged. In the beta-chains the replacements involve one heme-, one alpha 1/beta 1-, and one alpha 1/beta 2-contact. The alpha- and beta-chains of the Common Otter are compared to those of other Carnivora hemoglobins. The unexpected low number of substitutions between Common Otter hemoglobin and that of Lesser Panda as well as of Harbor Seal is discussed.     

Energy metabolism of underwater swimming in river-otters (Lutra lutra L.)

We used a still-water swim channel in conjunction with open-flow oxygen and carbon dioxide respirometry to examine the energy requirements of river-otters (Lutra lutra L.) swimming voluntarily underwater in Neumünster Zoo (Germany). While at rest on land (5 °C), river-otters had a respiratory quotient of 0.77 and a resting metabolic rate of 4.1 W kg⁻¹. This increased to an estimated 6.4 W kg⁻¹ during rest in water (11–15 °C) and to 12.3 W kg⁻¹ when the animals were feeding in the channel. River-otters swimming under water preferred a mean speed of 0.89 m s⁻¹, and their energy requirements attained 11.6 W kg⁻¹. Cost of transport, however, was minimal at 1.3 m s⁻¹ and amounted to 0.95 J N⁻¹ m⁻¹. Accepted: 3 November 1997     

Determinants of Eurasian otter (Lutra lutra) diet in a seasonally changing reservoir

Otter diet in reservoirs is known to experience seasonal changes. We selected a reservoir with a large population of exclusively wintering great cormorants and seasonal changes in stored water volume to test the relative influence of abiotic and biotic factors on otter foraging ecology. DNA metabarcoding of otter spraints revealed a dietary change from autumn to winter. Otters had a diet dominated by the exotic goldfish in autumn, but predated intensively on the native northern straight-mouth nase in winter. This change was likely caused by predation of cormorants on goldfish and to fish biology. Secondly, macroscopic analysis of spraints revealed that otters shifted from a diet dominated by fish (in terms of biomass) to a diet dominated by red swamp crayfish during spring–summer, when the latter became overabundant. As revealed by modelling, this second shift was most likely influenced by the sudden increase in stored water volume in spring, but also by the cumulative effect of cormorant predation on fish during autumn–winter. Macroscopic analyses of otter spraints collected in a second reservoir with no cormorants revealed a lack of seasonality. Hence, the combined influence of both biotic and abiotic factors explained otter diet seasonality in a lentic-water novel ecosystem.

     

The status of the otter (Lutra lutra) in the British Isles

National field surveys for otters were carried out between 1977 and 1981. The species is apparently absent from large areas of England, although healthy populations still occur in the south-west. In many other areas, populations are isolated and fragmented and there is some evidence for continuing declines. In Wales the otter is rare or absent from the south and parts of the north. Healthy populations are present in the Highland Region of Scotland, on the north and west coasts and in the islands but there is evidence of a decline in the south and east-central lowlands. Otters are widespread and common in Ireland which sustains the best of the known populations in Europe.
Pollution by pesticides probably caused the initial rapid decline of the species but habitat destruction is increasingly important and where habitat is poor, human disturbance assumes greater significance. There is no evidence of competition with mink. The otter is now a protected species but if it is to recover some of its former range, remaining habitat must be retained.
While otter populations have decreased over much of northern Europe, the animal survives, albeit somewhat precariously, in a few southern parts of the continent.     

Analyses of otter (Lutra lutra) faeces from Deeside, N.E. Scotland

Otter faeces were collected at monthly intervals from around two lakes near the River Dee in Aberdeenshire in 1975 and 1976. They were analysed to show the frequency of occurrence of identifiable undigested items and also the relative bulk of these different items. Statistical differences were recorded in frequency of occurrence. The main food was eel in both years with small perch also important in January to June and amphibia in the spring. A reduction in the frequency of eel in the faeces was associated with fewer observations of otters.     

Patterns of otter Lutra lutra road mortality in a landscape abundant in lakes

In order to reduce otter (Lutra lutra) road mortality and to predict accident sites, we assessed the localities of traffic accidents involving otters in the Uckermark County, Brandenburg, Northeast Germany. Eighty-eight otter accident sites from the years 1990 to 2003—as recorded by the Naturschutzstation Zippelsförde des Landesumweltamtes Brandenburg (Brandenburg State Office for Environment)—were categorised according to traffic and road patterns, otter habitat suitability, as well as presence and type of watercourse crossings. From these numerical data, we compiled a list of characteristics to identify other potentially dangerous sites where otter road traffic accidents are likely to occur using a geographic information system. With a principal component analysis, we categorised three groups of accident sites. Firstly, most otter road accidents were located close to either one or two lakes. Secondly, otters were frequently killed at places where no body of water occurred within a distance of 200 m to the road. Thirdly, and in contrast to other locations, in the Uckermark County, fewest accidents happened where a road crossed a watercourse. Mitigation measures were suggested and discussed for the recorded and potential accident sites.

     

Isospora lutrae n. sp. (Apicomplexa: Eimeriidae), a new coccidium from the European otter Lutra lutra (L.) (Carnivora: Mustelidae) from Spain

Parasitological examination of European otter originating from Extremadura, Spain revealed the presence of a new isosporan species. Oöcysts of Isospora lutrae n. sp. are spherical to subspherical, 31.2 (27.5–32) × 29.6 (28–31) m and have a smooth wall c. 1 m thick. Sporocysts are ellipsoidal, 18.2 (17–19) × 14.4 (14–16) m and lack Stieda and substieda bodies. A spherical sporocyst residuum is present, consisting of granules scattered among the sporozoites. Sporozoites are spindle-shaped, 12.4 × 2.5 m and have anterior and posterior refractile bodies. Based on its unique morphologic structure and host, I. lutrae is considered to be new.     

Characterizing habitat preference of Eurasian river otter (Lutra lutra) in streams using a self-organizing map

We studied the habitat preferences of Eurasian river otters (Lutra lutra) using the distribution patterns of the numbers of spraints and sprainting spots of otters, as well as related environmental variables (habitat zone, river management, bank type, vegetation coverage, width, depth, etc.) in two streams. The numbers of otter spraints and sprainting spots were sampled monthly in two streams on Geoje Island, Republic of Korea, from January to December 2004. Additional environmental variables were measured at the sampling sites. A self-organizing map (SOM), which is an unsupervised artificial neural network, was used to characterize the habitat preferences of otters. In our results, the SOM classified three different groups of study sites based on their habitat conditions, and the habitat differences were effectively visualized on the trained SOM map. Otters showed spatial and temporal dynamics in the numbers of spraints and sprainting spots, and revealed habitat preferences for shallow, narrow areas of streams and edges of water that were not far from reservoirs but covered with trees and shrubs. Additionally, otters preferred an environment in which weirs reduced the drift of water and gathered fishes and had a natural type of stream bank; these findings are relevant for river management. Otters adapted to places close to roads, residential areas, and agricultural areas with some tolerance of human interference.     

Isolation and characterization of tetramicrosatellite DNA markers in the Eurasian otter (Lutra lutra)

Eight new tetramicrosatellite loci for Eurasian otter (Lutra lutra) were designed. Polymorphism of these eight loci in 29 otter individuals was tested. The results indicated that the allele numbers of each of loci ranged from three to five and the observed heterozygosity from 0.483 to 0.828. These new loci can be useful for population genetic research on otters and help improve the resolution of individual identification using noninvasive method.