Showing papers in "Contributions to Zoology in 2000"
TL;DR: The commonest caligid copepod infesting commercial salmonid netpen systems in southern Chile is described as a new species, Caligus rogercresseyi, which belongs to the macarovigroup of species within the genus.
Abstract: The commonest caligid copepod infesting commercial salmonid netpen systems in southern Chile is described as a new species, Caligus rogercresseyi. This species belongs to the macarovigroup of species within the genus. It differs from Caligus flexispina Lewis 1964, with which it has previously been confused, in several important characters. These include the relatively elongate caudal rami, the proportions of the female genital complex and of the male abdomen, and the armature and ornamentation of the antenna in both sexes. The form of the sensillae associated with the postantennal process and the form of the male maxilliped are identified as possible additional diagnostic characters of the macarovi-group.
105 citations
TL;DR: Observations of whales and dolphins in the Cape Verde Islands obtained in 1995 and 1996 are reported and data on the occurrence of 14 taxa are given, including four not previously reported from the region, viz.
Abstract: Observations of whales and dolphins in the Cape Verde Islands obtained in 1995 and 1996 are reported and data on the occurrence of 14 taxa are given, including four not previously reported from the region, viz. Bryde’s Whale Balaenoptera edeni, Killer Whale Orcinus orca, Rough-toothed Dolphin Steno bredanensis, and Striped Dolphin Stenella coeruleoalba. An earlier report of Fin Whale B. physalus is reviewed and re-identified as B. cf. borealis. Status and occurrence of the Humpback Whale Megaptera novaeangliae are discussed at some length. Unpublished observations from other observers are also included and a short account on the history of whaling in the islands is given. A list of all cetacean taxa reliably recorded in the Cape Verde region is presented and unsubstantiated reports are briefly discussed.
72 citations
TL;DR: The present results show that eggs of salmon lice can develop to the infectious stage during winter along the Norwegian west coast with a pronounced simplification of hatching methods used earlier.
Abstract: To verify if and to what extent egg and nauplii development of the salmon lice take place during winter, the development from egg to the copepodid stage at 2,3,4,5 and 10°C was examined. Newly extruded egg strings from a winter population of salmon lice were individually placed in 6 ml stagnant hatching systems. Initially, no significant differences in egg development time were found between these and larger aerated systems, though a tendency for less synchronised hatching of the total egg string was detected in the stagnant systems (difference< 12 h). In light versus dark conditions the time to hatching was significantly prolonged by darkness (10-15%). The use of small stagnant experimental units was a pronounced simplification of hatching methods used earlier. At low temperature all but one pair of egg strings hatched. Time to first hatching was found to be 45.1±0.5 days at 2°C, 35.2±0.4 days at 3°C, 27.6±0.2 days at 4°C, 21.6±0.1 days at 5°C and 8.7±0.1 days at 10°C. The developmental time to hatching correlated to temperature fitted the polynomial function: Days to first hatching=0.6638 T² – 12.492T + 67.116 (R²=0.99). A high proportion of the nauplii developed to the copepodid (infectious stage) stage at 4°C and higher but only a small proportion at 2 and 3°C. Total developmental time to copepodid ranged from 12.7 days at 10°C to 68.5 days at 2°C or to the polynomial function Days to first copepodid = 1.0236 Tˉ² – 19.129 T + 101.5 (R²=0.995). The «physiological age» at hatching, i.e. the product of days and the respective temperature, showed not to be linearly correlated to temperature, but showed a maximum at 4°C. Average age at hatching was 90°days at 2°C and 110° days at 4°C. Thus the egg strings of the winter population appeared to be adapted to very low temperature by reducing the time for egg development. The present results show that eggs of salmon lice can develop to the infectious stage during winter along the Norwegian west coast.
71 citations
TL;DR: An international survey revealed that eleven compounds representing five pesticide types are currently being used on commercial salmon farms for sea lice control, with dichlorvos, Azamethiphos and cypermethrin were the most widely used compounds.
Abstract: An international survey revealed that eleven compounds representing five pesticide types are currently being used on commercial salmon farms for sea lice control. These include two organophosphates (dichlorvos and azamethiphos); three pyrethrin/pyrethroid compounds (pyrethrum, cypermethrin, deltamethrin); one oxidizing agent (hydrogen peroxide); three avermectins (ivermectin, emamectin and doramectin) and two benzoylphenyl ureas (teflubenzuron and diflubenzuron). The number of compounds available in any one country is highly variable, ranging from 9 (Norway) to 6 (Chile, United Kingdom) to 4 (Ireland, Faeroes, Canada) to 2 (US)). Dichlorvos, Azamethiphos and cypermethrin were the most widely used compounds (5 countries) followed by, hydrogen peroxide, ivermectin and emamectin (4 countries each), teflubenzuron (3 countries), diflubenzuron (2 countries), and deltamethrin, pyrethrum and doramectin (1 country each). Although, like trichlorfon, dichlorvos use is being discontinued in several countries notably Norway and the Faeroes. In most instances the availability of sea lice chemotherapeutants is limited, many being used under extra-label veterinary prescription or exemption, and special investigation permits. Access to a broad range of compounds with different modes of action, as well as application methods, has only recently been acquired making assessment of chemotherapy, and therefore integrated pest management, difficult.
71 citations
TL;DR: The geographic distribution of the endemic and threatened ebony leaf monkey Trachypithecus auratus (E. auratus) on the islands of Java, Bali, and Lombok (Indonesia) has been assessed in this paper.
Abstract: As one of the fundamental units of ecology and biogeography, the geographic distribution of the endemic and threatened ebony leaf monkey Trachypithecus auratus (E. Geoffroy Saint-Hilaire, 1812) on the islands of Java, Bali, and Lombok (Indonesia) has been assessed. All localities where the species has been collected are listed, and forty-two areas (each in itself consisting of numerous smaller sites) where the species has been recorded are discussed. The species occurs in a large variety of forest types, including mangrove, beach, and freshwater swamp forest; everwet lowland and hill forest; dry decidious forest; montane forest up to 3,000 – 3,500 m a.s.l.; and in some forest plantations (teak Tectona grandis, rasamala Altingia excelsa, acacia Acacia spp). In East Java, certain populations are dimorphic, containing, besides the more common melanic individuals, also erythristic individuals. This erythristic pelage morph only occurs in the easternmost part of Java of which the line between Mt. Penanggunang and the surroundings of Mojokerto running southwards, via Wonosalam and Blitar, to Mts Kidul roughly forms the western boundary. Localities where individuals of the erythristic pelage morph have been collected or observed are given.
67 citations
TL;DR: Recognition of new genera and reassignment of several species within the Cancrinae indicates that that subfamily may have arisen in the southern hemisphere, contrary to the previous interpretation of the subfamily as a primarily North Pacific or Tethyan group.
Abstract: New fossils referable to the Cancridae Latreille, 1802 extend the known stratigraphic range of the family into the middle Eocene and the geographic range into South America. Each genus within the family has been reevaluated within the context of the new material. A suite of diagnostic characters for each cancrid genus makes it possible to assign both extant and fossil specimens to genera and the two cancrid subfamilies, the Cancrinae Latreille, 1802, and Lobocarcininae Beurlen, 1930, based solely upon dorsal carapace morphology. Cheliped morphology is useful in assigning genera to the family but is significantly less useful at the subfamily and generic level. Each of the four subgenera sensu Nations (1975), Cancer Linnaeus, 1758, Glebocarcinus Nations, 1975, Metacarcinus A. Milne Edwards, 1862, and Romaleon Gistl, 1848, are elevated to full generic status. Additionally, three new genera and three new species accommodate the new, as well as some previously described taxa, and include Anatolikos new genus, Anisospinos berglundi new genus and species, and Notocarcinus sulcatus new genus and species and several new combinations. Recognition of new genera and reassignment of several species within the Cancrinae indicates that that subfamily may have arisen in the southern hemisphere, contrary to the previous interpretation of the subfamily as a primarily North Pacific or Tethyan group. The Lobocarcininae was primarily a Tethyan group.
49 citations
TL;DR: It seems that this species inhabits a wide variety of habitats (including secondary forest patches and the plantation-forest mosaic), and that its local distribution is not influenced by the Presence of any macrohabitat parameter.
Abstract: Several aspects of the ecology of Jameson’s green mamba Dendroaspis jamesoni jamesoni (Traill, 1843), a large-sized arboreal elapid snake, are studied in southern Nigeria. This species 18 common and widespread in the region studied. On the basis of the analysis of both the habitats of capture of the various specimens and the results of a logistical regression model, it seems that this species inhabits a wide variety of habitats (including secondary forest patches and the plantation-forest mosaic), and that its local distribution is not influencedby the Presence of any macrohabitat parameter. Green mambas were observed both in the dry and in the wet season, without any statistical bias toward a particular season. Adult sex-ratio was a Pproximately 1 : 1. Maleswere significantly longer than females. All adult mamba dietary records involved warm-blooded prey (mainly birds), whereas young mambas fed also upon lizards and toads. Nearly all the prey eaten by adult mambas were arboreal, and thus there was no support for the recent hypothesis that adult mambas develop anorientationto forageon terrestrial rodents. Male-male combats and matings were observed in December, January, and February (dry season), and gravid females were collected in April, May, and June (wet season). Females produced 7-16 eggs (mean 10.9), and litter size was Positively correlated with maternal length.
35 citations
TL;DR: In the skeletons of three species of Indomalayan bears, pathological changes are described that could be diagnosed as spondyloarthropathy and as discarthrosis/osteoarthrosis.
Abstract: In the skeletons of three species of Indomalayan bears, pathological changes are described that could be diagnosed as spondyloarthropathy and as discarthrosis/osteoarthrosis.
31 citations
TL;DR: The results suggest that the Salmon louse size is plastic and consequently a poor indicator of salmon louse origin.
Abstract: Salmon lice Lepeophtheirus salmonis (Kroyer, 1837) from farmed Atlantic salmon have been implicated in the drastic sea trout and salmon stock declines found in Ireland and Norway. Can salmon lice from farmed and wild fish be distinguished? The hypothesis has been advanced that the treatment of salmon infested with salmon lice with organophosphate pesticides has resulted in the evolution of early maturing, smaller female lice, which are favoured because they have the chance to reproduce before treatment. Salmon lice on wild fish have been reported to be larger and have more eggs in their egg strings (sacks) than lice on farmed fish. The question is whether the size differences between the lice are genetically fixed or an expression of phenotypic plasticity. In this study, lice from wild and farmed fish were collected and measured, and it was found that the former were significantly larger. When larvae from these two sources were raised on salmon at the same temperature, they bad the same growth rate and morphology. Larvae from the wild lice were raised at 8.7°C and 12.2°C, and attained a significantly larger size at the lower temperature. These results suggest that the salmon louse size is plastic and consequently a poor indicator of salmon louse origin.
30 citations
TL;DR: Ostracodes were the first major group to radiate, attaining high diversity during the Ordovician Period with other members of the Paleozoic evolutionary fauna; rates of extinction and responses to mass extinctions were also similar to those of groups within the paleozoic fauna.
Abstract: Approximately 2,600 genera of marine crustaceans have been recognized in the fossil record, and crustaceans constitute the major component of marine arthropod diversity from the mid-Paleozoic to the Recent. Despite problems of sporadic fossil preservation and/or taxonomic ambiguity, some general statements can be made about the history of crustacean biodiversity, based on global taxonomic data bases. Ostracodes were the first major group to radiate, attaining high diversity during the Ordovician Period with other members of the Paleozoic evolutionary fauna; rates of extinction and responses to mass extinctions were also similar to those of groups within the Paleozoic fauna. Malacostracans and barnacles (cirripedes), the two other crustacean groups with important fossil records, had minor diversity throughout the Paleozoic Era. Both groups experienced diversification from the mid-Mesozoic to Recent with lower extinction rates, as characteristic members of the Modern evolutionary fauna.
27 citations
TL;DR: The cuticle of the chalimus II stage of Lepeophtheirus salmonis (Copepoda: Caligidae) comprised a four-layered epicuticle with a pronounced fuzzy coat which was separated from the outer and inner procuticles by a layer of transitional procuticle.
Abstract: The cuticle of the chalimus II stage of Lepeophtheirus salmonis (Copepoda: Caligidae) comprised a four-layered epicuticle with a pronounced fuzzy coat which was separated from the outer and inner procuticles by a layer of transitional procuticle. The cuticle is underlain by a single-layered epidermis which overlies integumental glands and chromatophores. The structure of this cuticle is very similar to that described for free-living copepods and does not display the modifications associated with more highly transformed parasitic species.
TL;DR: Bath treatments for treating Atlantic salmon infested with sea lice, dichlorvos, azamethiphos, and hydrogen peroxide suggest potential toxicity due to high concentrations at low volumes and the risk of reduced sensitivity at high volumes.
Abstract: Licensed medicines available in the U.K. for treating Atlantic salmon infested with sea lice, dichlorvos, azamethiphos, and hydrogen peroxide, can only be administered by bath application. Adverse reactions have been reported to bath treatments including mortalities, inappetance, reduction in growth and reduced louse sensitivity to dichlorvos. The physical constraints of bath treatments are examined and improvements recommended. Oxygen saturation was adequate during treatments but declined rapidly when the tarpaulin was removed. A chemical marker dispersed uniformally both horizontally and vertically in a cage within 5 mins of dispensing indicating dispersal of a medicine is rapid and adequate during treatment. The range in enclosed volumes in 86 treatments was 46 to 146% of theoretical, suggesting potential toxicity due to high concentrations at low volumes and the risk of reduced sensitivity at high volumes. Residual concentrations of hydrogen peroxide varied from 50 to 400 ppm from 5 to 15 mins after the tarpaulin was removed. Water exchange should be encouraged by aerating the cage and flushing at the end of treatment.
TL;DR: The effects of short-term infection with the branchurian crustacean ectoparasite Argulus foliaceus, and the fish stress hormone cortisol, were studied on the mucous cell population of the head skin of rainbow trout.
Abstract: The effects of short-term infection with the branchurian crustacean ectoparasite Argulus foliaceus, and the fish stress hormone cortisol (which is reported to stimulate mucus discharge), were studied on the mucous cell population of the head skin of rainbow trout (Oncorhynchus mykiss). Argulus infection did not raise plasma cortisol significantly and had no effect on the number of epidermal mucous cells in the head skin. Cortisol was administered twice to groups of trout via the food, significantly elevating circulating plasma cortisol at 24 h post feeding without affecting numbers of mucous cells, and increasing the numbers of vesicles in the upper cells of the epidermis. Subsequent infection with the parasite (6 Argulus f/fish) did not affect either plasma cortisol or total numbers of mucous cells at 48 h post-infection with the parasite, but led to a significantly lower parasite infestation per fish in the cortisol-administered groups. A 24 h culture system was used to expose pieces of trout skin to 50 ng/ml cortisol in vitro to investigate whether cortisol alone would stimulate reductions in mucous cell numbers. These were unaffected by the addition of cortisol. The in vivo and in vitro results are discussed in relation to the current understanding of crustacean host-parasite interactions.
TL;DR: A method of the ghost range calculation is proposed to assess the congruence between a cladogram and the fossil record and to compare cladograms on this basis.
Abstract: A method of the ghost range calculation is proposed to assess the congruence between a cladogram and the fossil record and to compare cladograms on this basis. The method is tested on a set of cladograms developed recently to reveal the phylogeny of the hymenopterous insects (Order Vespida), and the results are discussed.
TL;DR: A novel application of a light-microscopy staining technique was utilised to reveal a variety of glands m nauplius, copepodid, chalimus, preadult and adult stages, which differentiated a population of exocrine glands and enabled a study of their distribution.
Abstract: The morphology, function and distribution of exocrine glands of copepods have rarely been studied in detail and almost nothing is known about them in the sea lice species L. salmonis and C. elongatus. This study utilised a novel application of a light-microscopy staining technique to reveal a variety of glands m nauplius, copepodid, chalimus, preadult and adult stages. The stain, 3’,3-diaminobenzidine tetrahydrochloride (DAB), applied to fresh material, differentiated a population of exocrine glands and enabled a study of their distribution. The stain was successful in highlighting the ducts and pores associated with the larger glands. The locations of gland sub-populations were conserved in all life-stages, although glands in the swimming legs were found to be better represented in mobile and freeswimming stages i.e. copepodids, preadults and adults. Glands associated with the mouth-tube were also located. Other, nonglandular, peroxidase-positive regions were also highlighted by the stain. These regions were found mainly in preadult and adult stages where they formed characteristic bi-symmetrical patterns on the cuticle of the dorsal surface. A study of some calanoid copepods suggested that peroxidase-positive glands are a feature peculiar to caligid copepods. This staining technique has proven useful for elucidating the ontogeny of gland populations in caligids.
TL;DR: The anatomy of the genital complex and the hook apparatus that keeps the trailing egg strings in position, are illustrated and described and a mechanism of operation is suggested.
Abstract: The anatomy of the genital complex and the hook apparatus that keeps the trailing egg strings in position, are illustrated and described. Based on light and scanning electron microscopy, it is shown how the sacs are mechanically secured by the penetration of a pair of hooks through the proximal ends of the strings. The muscle groups that move the hooks are described and a mechanism of operation is suggested.
TL;DR: Genetic differentiation within the salmon louse Lepeophtheirus salmonis, was investigated by the sequencing of specific nucleotide regions and the greater similarity between the ITS-1 sequence within farm sites may be attributed to a restricted gene flow within lice populations in Atlantic salmon cage sites.
Abstract: Genetic differentiation within the salmon louse Lepeophtheirus salmonis (Kroyer, 1837), was investigated by the sequencing of specific nucleotide regions. Partial sequences of the 18S ribosomal RNA gene and the ribosomal internal transcribed spacer (ITS-1) region from single sea lice were amplified by the polymerase chain reaction (PCR). Lice were collected from wild and farmed Atlantic salmon ( Salmo salar L., 1758) from nine selected localities around the Scottish coastline. A 0.9kb fragment of the 18S ribosomal RNA gene was amplified and compared for several samples of lice which showed no observable differences between the lice from different collection sites confirming the absence of cryptic species. The 454 nucleotide ITS-1 sequence showed differences between derived sequences from 13 sea lice samples from 4 collection sites which included 2 farm sites and 2 sites where lice were taken from wild fish. Across all samples, there was a 92.14% similarity in the ITS-1 sequence. The percentage similarity in the ITS-1 sequence in samples office from two fish farms were 99.71% (site A) and 95.72% (site D) but only 86.90% (site B) and 86.03% (site C) similarity was shown in lice samples taken from sites where wild salmonids were caught. The greater similarity between the ITS-1 sequence within farm sites may be attributed to a restricted gene flow within lice populations in Atlantic salmon cage sites.
TL;DR: The investigation of specific characteristics of Lepeophtheirus salmonis populations on farmed salmon was made possible by the examination of the parasite infestation parameters of regular non destructive samples taken for up to six years in five bays.
Abstract: The investigation of specific characteristics of Lepeophtheirus salmonis populations on farmed salmon was made possible by the examination of the parasite infestation parameters of regular non destructive samples taken for up to six years in five bays. Perennial persistence of seasonal patterns of infestation as exhibited by intensity, prevalence and abundance was examined. Site specific characteristics were detected which appeared to be independent of inter-annual variations. Seasonal variations in individual lice size and fecundity, and temporal variation in population dynamics on the farmed fish in the five bays are considered in the context of the not inconsiderable changes in husbandry and lice control practices which have been introduced in the industry over the six year period.
TL;DR: Differences were found in the relative prevalence of infestation between salmon and rainbow trout and Caligus elongatus generally contributed more as a proportion of the total lice burden on rainbow trout than on Atlantic salmon.
Abstract: Infestation patterns of Caligus elongatus on farmed Atlantic salmon and rainbow trout were investigated at several sites along the west coast of Ireland. Parasite abundances were examined in relation to host species, farm location and season. Differences were found in the relative prevalence of infestation between salmon and rainbow trout. Caligus elongatus generally contributed more as a proportion of the total lice burden on rainbow trout than on Atlantic salmon. Evidence of possible parasite transmission from wild fish stocks was found at a number of sites where marked seasonal changes in parasite abundance were observed. A wide size distribution of adult female Caligus elongatus was found at a number of sites.
TL;DR: The results of the single element comparisons showed that not all individual sites could be discriminated from each other as mentioned in this paper, while 12 elements still provided 9730% correct classification, and the effects of sequentially removing elements from the discrimination model in order to determine the minimum number of elements required to obtain satisfactory discrimination of populations.
Abstract: Conventional nebulisation ICPMS (Inductively Coupled Plasma Mass Spectrometry), was used to determine the concentration of a broad range of elements in the salmon louse Lepeophtheirus salmonis Lice samples were collected from Atlantic salmon in seven localities (4 fish farms and 3 wild salmon fisheries) on two separate sampling occasions and prepared for analysis Sixty six elements were measured, 35 of these were found to be variable and were subjected to univariate and multivariate statistical analysis The results of the single element comparisons showed that not all individual sites could be discriminated from each other Sea lice collected from cultured salmonids could be discriminated from those on wild salmonids at the same site using the elements magnesium (<005%), vanadium (<001 %) and uranium (<005%) Using discriminant analysis based on 28 elements, the separation of all sampled sea lice localities from each other was clear (100% correct classification) giving each an individual signature Further analysis examined the effects of sequentially removing elements from the discrimination model in order to determine the minimum number of elements required to obtain satisfactory discrimination of populations It was found that 16 elements could still provide 100% correct classification, whilst 12 elements still provided 9730% correct classification This pilot study has shown elemental analysis to be a potentially successful method for the discrimination of populations of L salmonis, although the biological basis of the elemental signatures derived remains to be established
TL;DR: A new taxon Metaprosekia gen.n.
Abstract: In a collection of terrestrial isopods from Venezuela, a distinct species was identified which does not fit any of the known genera. Therefore, a new taxon Metaprosekia gen.n. is instituted to accomodate the new species. An analysis of its morphological characters revealed a close relationship to the genus Prosekia Vandel, 1968 and allied genera. The phylogeny of this group is discussed and one of its poorly known representatives, Xiphoniscus mirabilis Vandel, 1968 is redescribed on the basis of the type material.
TL;DR: The ultrastructure of moulting in the chalimus phase of the parasitic caligid copepod Lepeophtheirus salmonis is described for the first time and the major features of the moult sequence correspond to those of other Crustacea, save for the absence of a distinguishable intermoult.
Abstract: The ultrastructure of moulting in the chalimus phase of the parasitic caligid copepod Lepeophtheirus salmonis is described for the first time. The major features of the moult sequence correspond to those of other Crustacea, save for the absence of a distinguishable intermoult as defined by reduced epidermal activity and a cessation of cuticle production. This latter may be explained cither in terms of a continuous moulting process related to the constant food supply available to a parasite or in terms of a highly abbreviated intermoult period. The findings are discussed with respect to studies of other Crustacean species.
TL;DR: For smoltifying Atlantic salmon, the No Observed Pathological Effect (NOPE) level for exposure for ZNSO4 may be around 150 ppb, which suggests that overall stress effects were low.
Abstract: Smoltifying Atlantic salmon were treated for 6 weeks in freshwater with 0, 200, and 400 ppb zinc (as Zn SO4). After 6 weeks salmon were transferred to a salt water seapen and exposed to infection with Lepeophtheirus salmonis for 14 weeks. Zinc treatment resulted in some physiological changes consistent with increased stress, such as decreased leukocrit values, and increased plasma cortisol levels. Plasma glucose levels were significantly elevated in fish previously treated with zinc, but this was only evident after fish had been in a seapen, 14 weeks subsequent to treatment. Improved conversion of tetraiodothyronine to triiodothyronine, as well as no changes in interrenal cell nuclear diameters suggested that overall stress effects were low. Fish exposed to 200 ppb and 400 ppb zinc showed gill pathology. Infection intensity with L. salmonis was significantly higher on salmon previously exposed to 400 ppb zinc. This research suggests that for smoltifying Atlantic salmon, the No Observed Pathological Effect (NOPE) level for exposure for ZNSO4 may be around 150 ppb.
TL;DR: Where the species names proposed by Vosmaer are synonyms of those published by Pallas in the same volume, the latter are selected, because some names have been validly used before with Pallas as the author.
Abstract: On 6 October 1764, Adriaan Vroeg sold his collection of birds, insects and a few other animals by auction The sales catalogue was published anonymously, but contained several scientific names of birds, which have nomenclatorial standing Only three copies of this catalogue are known The appendix entitled “Adumbratiunculae” has previously been attributed to Peter Simon Pallas, who is quoted as author of the new names of birds In the present note, the main text is credited to Arnout Vosmaer, on the basis of contemporary references Where the species names proposed by Vosmaer are synonyms of those published by Pallas in the same volume, the latter are selected, because some names have been validly used before with Pallas as the author