Ocelot distribution in the Lower Rio Grande Valley National Wildlife Refuge

Weaver hair-snaring surveys were conducted at 125 sites on 27 Refuge tracts to obtain information about the distribution and population status of the endangered ocelot ( Leopardus pardalis ) in the Lower Rio Grande Valley National Wildlife Refuge. The surveys resulted in 33.6% of the pads “hit”, including 8 by ocelot and 29 by bobcat. There was no significant difference in the number of ocelot hits between warm and cool seasons or between the sexes. Preferred habitat consists of dense thornscrub brush. Four species, snake-eyes, granjeno, honey mesquite, and colima comprise 50% or more of the total cover at each site where ocelots were detected. The ocelot sites averaged 146% total cover and 58.7% community similarity, as well as showing a significant interaction between the presence of snake eyes and colima with that of ocelot

Changes to Tensile Strength and Electromagnetic Shielding Effectiveness in Neutron Irradiated Carbon Nanocomposites

Electromagnetic interference shielding effectiveness (EMI-SE) and tensile strength of nanocomposites containing multi-walled carbon nanotubes (MWNTs) are investigated following neutron irradiation. This nanocomposite material consists of two plies of MWNTs in an epoxy resin, and 4 plies of an E-glass substrate. EMI-SE measurements over the X-band frequency spectrum and monotonic tension tests to determine Young’s Modulus were performed before and after irradiation on the nanocomposite material. The nanocomposite and the MWNT plies were irradiated to a total fluence of 1.4 × 1014 1 MeV (Si-eq) n/cm2. The nanocomposites showed an average increase of 8 dB in shielding effectiveness after irradiation. However, the increase was not permanent with a return to pre-irradiation values after approximately 10 days at ambient temperature and pressure. The tensile strength and Young’s Modulus showed an 8% and 10% increase, respectively, following irradiation. This small increase is a result of the neutron induced embrittlement of the nanocomposite. Raman spectra of the MWNT plies showed a 150% increase in the D/G peak ratios after irradiation. This indicates damage in the plies due to neutron interactions in the MWNTs that does not lead to a commensurate reduction in EMI-SE or tensile strength in the nanocomposite material

Discrimination of gyrodactylids based on landmark data

First paragraph: There are many different species of the genus Gyrodactylus. One particular form, Gyrodactylus salaris, is known to be highly pathogenic to stocks of Atlantic salmon, whereas other species that infect salmonids have a generally low pathogenicity. Gyrodactylus salaris is responsible for the catastrophic decline in salmon stocks in Norway and has been demonstrated to be widespread in Norwegian rivers. It has also caused problems in Portugal and France. In order to prevent its entry into the UK, G. salaris was made a notifiable disease in 1988 under the 1937 and 1983 Diseases of Fish Acts of the UK. While the UK is thought to be free of G. salaris there is another species, G. thymalli which has been found in the UK and some think is a variant of G. salaris. It is important to find a means of identification of G. salaris via routine microscopic monitoring of samples of parasites. Hence the main motivation for this work is the development of a statistical method which could be used to discriminate G. salaris from other species of Gyrodactylus, while a secondary aim is the discrimination of the other species of Gyrodactylus from each othe

The use of statistical classifiers for the discrimination of species of the genus Gyrodactylus (Monogenea) parasitizing salmonids

This study applies flexible statistical methods to morphometric measurements obtained via light and scanning electron microscopy (SEM) to discriminate closely related species of Gyrodactylus parasitic on salmonids. For the first analysis, morphometric measurements taken from the opisthaptoral hooks and bars of 5 species of gyrodactylid were derived from images obtained by SEM and used to assess the prediction performance of 4 statistical methods (nearest neighbours; feed-forward neural network; projection pursuit regression and linear discriminant analysis). The performance of 2 methods, nearest neighbours and a feed-forward neural network provided perfect discrimination of G. salaris from 4 other species of Gyrodactylus when using measurements taken from only a single structure, the marginal hook. Data derived from images using light microscopy taken from the full complement of opisthaptoral hooks and bars were also tested and nearest neighbours and linear discriminant analysis gave perfect discrimination of G. salaris from G. derjavini Mikailov, 1975 and G. truttae Gläser, 1974. The nearest neighbours method had the least misclassifications and was therefore assessed further for the analysis of individual hooks. Five morphometric parameters from the marginal hook subset (total length, shaft length, sickle length, sickle proximal width and sickle distal width) gave near perfect discrimination of G. salaris. For perfect discrimination therefore, larger numbers of parameters are required at the light level than at the SEM level

Discrimination of the notifiable pathogen Gyrodactylus salaris from G-thymalli (Monogenea) using statistical classifiers applied to morphometric data

The identification and discrimination of 2 closely related and morphologically similar species of Gyrodactylus, G. salaris and G. thymalli, were assessed using the statistical classification methodologies Linear Discriminant Analysis (LDA) and k-Nearest Neighbours (KNN). These statistical methods were applied to morphometric measurements made on the gyrodactylid attachment hooks. The mean estimated classification percentages of correctly identifying each species were 98±1% (LDA) and 97±9% (KNN) for G. salaris and 99±9% (LDA) and 73±2% (KNN) for G. thymalli. The analysis was expanded to include another 2 closely related species and the new classification efficiencies were 94±6%(LDA) and 98±0% (KNN) for G. salaris; 98±2% (LDA) and 72±6% (KNN) for G. thymalli; 86±7% (LDA) and 91±8% (KNN) for G. derjavini ; and 76±5% (LDA) and 77±7% (KNN) for G. truttae. The higher correct classification scores of G. salaris and G. thymalli by the LDA classifier in the 2-species analysis over the 4-species analysis suggested the development of a 2-stage classifier. The mean estimated correct classification scores were 99±97% (LDA) and 99±99% (KNN) for the G. salaris±G. thymalli pairing and 99±4% (LDA) and 99±92% (KNN) for the G. derjavini±G. truttae pairing. Assessment of the 2-stage classifier using only marginal hook data was very good with classification efficiencies of 100% (LDA) and 99±6%(KNN) for the G. salaris±G. thymalli pairing and 97±2%(LDA) and 9±2%(KNN) for the G. derjavini±G. truttae pairing. Paired species were then discriminated individually in the second stage of the classifier using data from the full set of hooks. These analyses demonstrate that using the methods of LDA and KNN statistical classification, the discrimination of closely related and pathogenic species of Gyrodactylus may be achieved using data derived from light microscope studies

Innovative solutions for aquaculture: Assessment of in situ monitoring techniques and life history parameters for monogenean skin and gill parasites

First paragraph: External parasitic flukes that infect the skin and gills of yellowtail kingfish are among the most serious health issues for the culture of this species. Fingerlings grown in land-based hatcheries are free of parasites when transferred to sea-cages for grow out. The skin and gill parasites occur naturally and infect wild yellowtail kingfish stocks. Fluke populations proliferate on captive, seacaged stocks due to the direct lifecycle of the two parasite species. Fluke infections require regular monitoring by farm staff throughout the production cycle of yellowtail kingfish. Infections contribute to reduced growth, morbidity and if fluke populations reach sufficient intensity, the parasites can cause kingfish mortality on farms

Elemental analysis of Scottish populations of the ectoparasitic copepod Lepeophtheirus salmonis

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 (less than 0.05%), vanadium (less than 0.01%) and uranium (less than 0.05%). 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 97.30% 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

Role of kairomones in host location of the pennellid copepod parasite, Lernaeocera branchialis (L. 1767)

The life cycle of the parasitic copepod Lernaeocera branchialis involves 2 hosts, typically a pleuronectiform host upon which development of larvae and mating of adults occurs and a subsequent gadoid host, upon which the adult female feeds and reproduces. Both the copepodid and adult female stages must therefore locate and identify a suitable host to continue the life cycle. Several mechanisms are potentially involved in locating a host and ensuring its suitability for infection. These may include mechano-reception to detect host movement and chemo-reception to recognize host-associated chemical cues, or kairomones. The aim of this study was to identify the role of kairomones in host location by adult L. branchialis, by analysing their behaviour in response to fish-derived chemicals. Experiments demonstrated that water conditioned by immersion of whiting, Merlangius merlangus, elicited host-seeking behaviour in L. branchialis, whereas cod- (Gadus morhua) conditioned water did not. Lernaeocera branchialis are considered a genetically homogeneous population infecting a range of gadoids. However, their differential response to whiting- and cod-derived chemicals in this study suggests that either there are genetically determined subspecies of L. branchialis or there is some form of environmental pre-conditioning that allows the parasite to preferentially recognize the host species from which it originated