The earthworms of arable and pasture fields from 100 randomly chosen arable farms were identified and counted and their relationship with soil factors examined. Thirteen species of earthworm were recorded including Lumbricus friendi from Scotland for the first time. The most prevalent and numerous species were Aporrectodea longa, Aporrectodea caliginosa and Lumbricus terrestris. All earthworm species had cosmopolitan distributions apart from Aporrectodea nocturna and Lumbricus festivus which were confined to southerdcentral Scotland. Four soil characteristics (% moisture, % sand, % organic matter and pH) shared no relationship with species recorded but tillage may have had a detrimental effect on species composition and size of population. It is suggested that the magnitudes of the earthworm populations found, particularly in permanent pasture, were important in maintaining soil structure and fertility, and the spread of the New Zealand flatworm (Artioposthia triangulata), an obligate predator of earthworms, could have a considerable impact on agricultural productivity and wildlife in Scotland. This paper reports the results of an investigation into the distribution of earthworms occurring in Scotland and aims to define their prevalence and intensity in agricultural soil and to study the factors potentially influencing their populations. Materials and MethodsA stratified random sample of 100 arable farms from throughout Scotland was generated from the 1990 census returns to the Scottish Office Agriculture and Fisheries Department. These farms were visited between July 1991 and June 1992 and wherever possible earthworms were counted from one arable and one permanent pasture field. However, only 56 farms had both field types and, of the remainder, 38 farms had permanent pasture fields only and six farms arable fields only. In a randomly selected area of each field, five 0.5 m square metal quadrats were sunk 5-10 cm into the ground at 10 m intervals in a polygonal array. If present, vegetation was cut to ground level and removed prior to two applications of 4.5 litres of 0.5% formaldehyde solution (Raw, 1959). Hand sorting is time consuming but considered the most efficient way of detecting and quantifying most earthworm species while the use of formalin is known to work well for deep-burrowing species. An initial comparison of these two techniques (unpublished data) indicated that the use of formalin gave results which showed similar extraction efficiencies for both arable and pasture fields the respective values being 30. I % and 29.1 %. There were differences in the efficiency with which different species were extracted using the formalin extraction procedure, e.g. for Aporrectodea caliginosa and Fig. I , Distribution of 10 lan squares containing farms which were sampled, 0 are those in which A.nocfurnu, and L. festivus, 0 were present. Annual rainfall; below 100 mm, no shading; between 100-150 mm. dark shading; above 200 mrn, intermediate shading.

The abundance, distribution and oxidative capacities of mitochondria have been investigated in the red pectoral fin adductor muscles of fish (Order Perciformes) that use a predominantly labriform style of swimming. Mediterranean Sea species from the families Labridae, Serranidae, Sparidae and Antarctic Nototheniidae and non-Antarctic Nototheniidae and Channichthyidae were studied. Sub-Antarctic species from the Beagle Channel, Tierra del Fuego, included the pelagic haemoglobin-less icefish (Champsocephalus esox) and the robalo (Eleginops maclovinus), which occurs as far north as 35 degrees S. In Champsocephalus esox, the mitochondrial volume density of red muscle was 0.51 and mitochondrial cristae surface density (43. 9 microm2 microm-3) was higher than reported for Antarctic icefishes. In the red-blooded, active pelagic or semi-pelagic species, mitochondrial volume density was within the range 0.27-0.33 regardless of habitat temperature. Amongst less active demersal species, mitochondrial volume density ranged from 0.29-0.33 in polar species to 0.08-0.13 in Mediterranean species. In Antarctic species and Champsocephalus esox, myofibrils occurred in ribbons or clusters one fibril thick entirely surrounded by mitochondria. The volume density of intracellular lipid droplets was not correlated with activity patterns or habitat temperature. In a comparison of Eleginops maclovinus caught in summer (approximately 10 degrees C) and winter (approximately 4 degrees C), mitochondrial volume density did not differ, whereas the surface density of mitochondrial clusters was higher in summer fish. The temperature-dependence of the state 3 respiration rate of isolated mitochondria with pyruvate as substrate was described by a single quadratic relationship for all species, indicating no significant up-regulation of the maximum rate of oxygen uptake per milligram mitochondrial protein in Antarctic species. Our results support the conclusion that increasing the volume and surface density of mitochondrial clusters is the primary mechanism for enhancing the aerobic capacity of muscle in cold-water fish.

The distribution of the New Zealand flatworm (Artioposthia triangulata) in Scotland was surveyed between July 1991 and February 1993. There were 348 records from domestic gardens, 56 from botanic gardens, garden centres and nurseries, with only 13 from farms. Although most of the records came from around the major cities the flatworm was found to have become established throughout the Scottish mainland and some of the Islands, e.g. Bute, Gigha, Orkney and Skye.The impact of the flatworm on earthworm populations in agricultural land in Scotland was, as yet, found to be minimal but the fact that seven adjacent farms near Dunoon were infected suggested it could be spread from farm to farm and that in the West of Scotland it could become widespread in agricultural land.

Studies have shown the New Zealand flatworm to be a predator of earthworms and to be widely distributed throughout most of Ireland and Scotland. Except for one record in 1965, it had not been found in England until, in December 1992, it was positively identified from a garden centre near Manchester. Viable and empty egg capsules were also found suggesting that it had reproduced and become established in that nursery. During 1993 other confirmed reports were received from Yorkshire and East Anglia, indicating that it may be able to survive and multiply across large areas of England.

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