Establishing climate–growth relationships for yelloweye rockfish (Sebastes ruberrimus) in the northeast Pacific using a dendrochronological approach

We applied dendrochronology (tree‐ring) methods to develop multidecadal growth chronologies from the increment widths of yelloweye rockfish (Sebastes ruberrimus) otoliths. Chronologies were developed for the central California coast, a site just north of Vancouver Island, British Columbia, and at Bowie Seamount west of the Queen Charlotte Islands, British Columbia. At each site, synchronous growth patterns were matched among otoliths via the process of cross‐dating, ensuring that the correct calendar year was assigned to all increments. Each time series of growth‐increment measurements was divided by the values predicted by a best‐fit negative exponential function, thereby removing age‐related trends. These detrended time series were averaged into a master chronology for each site, and chronologies were correlated with monthly averages of sea surface temperatures, upwelling, the Northern Oscillation Index, and the Pacific Decadal Oscillation. The two northern growth chronologies positively correlated with indices of warm ocean conditions, especially from the prior summer through the spring of the current year. During the same period, the California chronology positively correlated with indices of cool ocean conditions, indicating an opposing productivity regime for yelloweye rockfish between the California Current and the Gulf of Alaska. Overall, this study demonstrates how tree‐ring techniques can be applied to quickly develop annually resolved chronologies and establish climate–growth relationships across various temporal and spatial scales.     

Appropriate bacterial identification systems for small plant-pathology laboratories overseas incorporating the Biolog method

Diagnostic services in developing countries are severely limited by the availability of funding and trained personnel. While common fungal pathogens can be identified with minimal equipment and media, the conventional methods for identification of bacterial pathogens are time-consuming and require a wide range of costly media and reagents. In addition, excessive time and resources are often devoted to the identification of contaminating saprophytic bacteria. The Biolog system for identifying bacteria by metabolic profiles has been evaluated and adapted for use in routine diagnosis in small plant pathology laboratories overseas. Although Biolog is costly, it can be combined with a system for the preliminary identification and elimination of non-pathogens using a limited number of conventional tests. The database of Gram-negative profiles supplied by Biolog needs to be supplemented by user-defined database(s). Bacterial Identifier software (Blackwell Scientific Publications) is advocated as a cost-effective alternative.     

Current distribution of sarcoptic mange in wombats

Objective To determine the distribution and prevalence of sarcoptic mange in wombats, particularly the common wombat ( Vombatus ursinus ).
Design Questionnaire survey in two parts.
Procedure Questionnaires were distributed to biologists, rangers, animal carers and naturalists. Part 1 of the questionnaire aimed to determine the present distribution of sarcoptic mange in wombats (103 responses). Part 2 invited respondents to assess the prevalence of sarcoptic mange in wombats over a 3 month period (four responses). Information on wombats from 66 localities was received. Each locality represented an area of about 2500 km².
Results Mange was observed at 93% of localities surveyed and Sarcoptes scabiei was present in common wombats at 52% of localities. Sarcoptic mange was highly prevalent (22%) in two common wombat populations in Victoria. Anecdotal evidence suggested that mange epizootics are sporadic, cause significant morbidity and mortality and have a substantial effect on local abundance. The respondents did not report sarcoptic mange in either northern hairy-nosed wombats ( Lasiorhinus krefftii ) or southern hairy-nosed wombats ( Lasiorhinus latifrons ).
Conclusions Sarcoptic mange occurs in common wombat populations throughout the range of the common wombat including Tasmania and Flinders Island. While mange epizootics are sporadic, they have the potential to threaten the long-term survival of small, remnant populations.     

Confirmation of spatial patterns and temperature effects in Bluetongue virus serotype-8 transmission in NW-Europe from the 2007 reported case data

Two separate analyses were carried out to understand the epidemiology of Bluetongue virus serotype 8 (BTV-8) in 2007 in North West Europe: First, the temporal change in transmission rates was compared to the evolution of temperature during that season. Second, we evaluated the spatio-temporal dynamics of newly reported outbreaks, to estimate a spatial transmission kernel. For both analyses, the approach as used before in analysing the 2006 BTV-8 epidemic had to be adapted in order to take into account the fact that the 2007 epidemic was not a newly arising epidemic, but one advancing from whereto it had already spread in 2006. We found that within the area already affected by the 2006 outbreak, the pattern of newly infected farms in 2007 cannot be explained by between-farm transmission, but rather by local re-emergence of the virus throughout that region. This indicates that persistence through winter was ubiquitous for BTV-8. Just like in 2006, we also found that the temperature at which the infection starts to spread lies close to 15 °C. Finally, we found that the shape of the transmission kernel is in line with the one from the 2006 epidemic. In conclusion, despite the substantial differences between 2006 and 2007 in temperature patterns (2006 featured a heat wave in July, whereas 2007 was more regular) and spatial epidemic extent, both the minimum temperature required for transmission and the transmission kernel were similar to those estimated for the 2006 outbreak, indicating that they are robust properties, suitable for extrapolation to other years and similar regions.     

Spatial Variability of Turbulent Mixing in the Abyssal Ocean

Ocean microstructure data show that turbulent mixing in the deep Brazil Basin of the South Atlantic Ocean is weak at all depths above smooth abyssal plains and the South American Continental Rise. The diapycnal diffusivity there was estimated to be less than or approximately equal to 0.1 x 10(-4) meters squared per second. In contrast, mixing rates are large throughout the water column above the rough Mid-Atlantic Ridge, and the diffusivity deduced for the bottom-most 150 meters exceeds 5 x 10(-4) meters squared per second. Such patterns in vertical mixing imply that abyssal circulations have complex spatial structures that are linked to the underlying bathymetry.     

BOOK REVIEW

ECG Interpretation in Dogs and Cats, Video produced by Provet for the Unit of Veterinary Continuing Education of the Royal Veterinary College     

Electrophoretic variation in triazine-resistant and-susceptible populations of the allogamous weed Brassica rapa

Levels of genetic variation, as estimated from electrophoretic data, were investigated in three triazine-resistant (R) and seven susceptible (S) populations of the allogamous weed Brassica rapa ssp. sylvestris (L.) Jan, from Ouebec, Canada. No significant differences were detected between R and S populations in the percentage of polymorphic loci (37–39.2%), but allelic diversity (mean number of alleles per locus) and observed and expected levels of heterozygosity were significantly (P<0.10) lower in the R populations than in the S populations. Overall low levels of population differentiation were evident among populations. Nei's genetic distances between population pairs ranged from 0.003 to 0.054, with an overall species mean of 0.019, with slightly greater divergence among the three R populations. Most of the total gene diversity was found within populations for both S and R populations. A mean of 3.7% of the variation occurred among S populations, with a higher value of 12.1% distributed among the R populations. A comparison of observed levels of heterozygosity with expected levels under random mating, provided evidence for significant departures from random mating, as lower mean values than expected were observed for both the R populations (0.133 vs. 0.153) and S populations (0.159 and 0.184), suggesting that a low level of selfing may be occurring in these populations. The distribution of genetic variation among and within populations of B. rapa was consistent with predicted pattems for predominantly allogamous species. The reduced levels of genetic variation observed for the three R populations were not as striking as that previously reported for triazine-resistant auto-gamous species. Variation électrophorètique chez les populations risistantes et sensibles aux triazines de l'adventice allogame Brassica rapa Les niveaux de variation génétique, estimés a partir de données venant de l'électrophorèse ont étéétudiés chez 3 populations résistantes aux triazines (R) et 7 sensibles (S) de l'adventice allogame Brassica rapa ssp sylvestris (L.) Jan, du Quebec, Canada, Aucune différence significative n'a été trouvée entre les populations R et S dans le pourcentage des loci polymorphes, mais la diversité allélique (nombre moyen d'allèles par locus) et les taux d'heterozygosité attendus et observés étaient significativement (P<0,10) moins élevés chez les populations R que chez les S. En général de faibles niveaux de différenciation de populations apparaissaient dans les populations. Les distances génétiques entre 2 populations allaient de 0,003 à 0,054, avec une moyenne générale de l'espfèce de 0,019 avec une légèrement plus élevée divergence dans les 3 populations R. La majorité de la diversité génetique était trouvée a l'intérieur des populations tant S que R. Une moyenne de 3,7% de variation est apparue dans les populations S, avec une valeur plus élevée de 12,1% dans les populations R. Une comparaison des niveaux d'heterozygosité observés avec ceux attendus avec croisement au hasard, a montré une différence significative, avec des valeurs moyennes observées, plus basses que celles attendues à la fois pour les populations R (0,133 contre 0,153) et pour les S (0,159 et 0,184), donnant à penser qu'un faible taux d'autofécondation peut survenir dans ces populations. La distribution de la variation génétique dans les populations de B. rapaétait conforme au schéma prévisible pour une espèce majoritairement allogame. Les niveaux réduits de variation génétique observés pour les 3 populatioiis résistantes n'étaient pas aussi marquant que ce qui avait été précédemment décrit pour des espèces résistantes aux triazines autogames. Elektrophoretische Untersuchung der genetischen Unterschiede Triazin-resistenter und-empfindlicher Populationen von Brassica rapa Bei der Untersuchung der genetischen Unterschiede 3 Triazin-resistenter (R) und 7 -empfindlicher (S) Populationen des allogamen Unkrauts Brassica rapa ssp. sylvestris (L.) Jan. aus Quebec, Kanada, war aufgrund elektropho-retischer Daten der Prozentsatz polymorpher Loci bei R- und S-Populationen nicht signifikant verschieden (37…39,2%), aber die Allel-diversität (mittlere Anzahl Allele pro Locus) und der beobachtete und erwartete Grad der Heterozygotie waren bei den R-Populationen signifikant geringer (P<0,10) als bei den S-Populationen. Die Populationen waren offen-sichtlich allgemein wenig differenziert. Die genetische Distanz zwischen Populationen-paaren reichte von 0,003 bis 0,054 mit einem Artmittel von 0,019 und bei etwas größerer Divergenz der 3 R-Populationen. Bei den S-Populationen lag das Variationsmittel bei 3,7%, höher bei den R-Populationen mit 12,1%. Beim Vergleich der beobachteten Heterozygotie mit der erwarteten ergeben sich signifikante Abweichungen von der zufäligen Paarung, indem sowohl fur die R- als auch für die S-Populationen geringere Werte gefunden wurden (0,133 gegen 0,153 bzw. 0,159 und 0,184), ein Hinweis auf eine geringe Selbstbe-fruchtung. Die genetischen Unterschiede zwischen und in den Brassica-rapa-Populationen entsprach dem Muster vorwiegend allogamer Arten. Die geringeren genetischen Unterschiede der 3 R-Populationen waren nicht so überraschend wie die früher berichtenen von Triazin-resistenten autogamen Arten.