Random and systematic sampling error when hooking fish to monitor skin fluke (Benedenia seriolae) and gill fluke (Zeuxapta seriolae) burden in Australian farmed yellowtail kingfish (Seriola lalandi)

© 2018 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license:http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 12 month embargo from date of publication (February 2018) in accordance with the publisher’s archiving policyThe Australian farmed yellowtail kingfish (Seriola lalandi, YTK) industry monitor skin fluke (Benedenia seriolae) and gill fluke (Zeuxapta seriolae) burden by pooling the fluke count of 10 hooked YTK. The random and systematic error of this sampling strategy was evaluated to assess potential impact on treatment decisions. Fluke abundance (fluke count per fish) in a study cage (estimated 30,502 fish) was assessed five times using the current sampling protocol and its repeatability was estimated the repeatability coefficient (CR) and the coefficient of variation (CV). Individual body weight, fork length, fluke abundance, prevalence, intensity (fluke count per infested fish) and density (fluke count per Kg of fish) were compared between 100 hooked and 100 seined YTK (assumed representative of the entire population) to estimate potential selection bias. Depending on the fluke species and age category, CR (expected difference in parasite count between 2 sampling iterations) ranged from 0.78 to 114 flukes per fish. Capturing YTK by hooking increased the selection of fish of a weight and length in the lowest 5th percentile of the cage (RR = 5.75, 95% CI: 2.06–16.03, P-value = 0.0001). These lower end YTK had on average an extra 31 juveniles and 6 adults Z. seriolae per Kg of fish and an extra 3 juvenile and 0.4 adult B. seriolae per Kg of fish, compared to the rest of the cage population (P-value < 0.05). Hooking YTK on the edge of the study cage biases sampling towards the smallest and most heavily infested fish in the population, resulting in poor repeatability (more variability amongst sampled fish) and an overestimation of parasite burden in the population. In this particular commercial situation these finding supported that health management program, where the finding of an underestimation of parasite burden could provide a production impact on the study population. In instances where fish populations and parasite burdens are more homogenous, sampling error may be less severe. Sampling error when capturing fish from sea cage is difficult to predict. The amplitude and direction of this error should be investigated for a given cultured fish species across a range of parasite burden and fish profile scenarios

Mitigating disease risk in an endangered pinniped: early hookworm elimination optimizes the growth and health of Australian sea lion pups

The Australian sea lion (Neophoca cinerea) experiences high pup mortality of seasonally alternating severity, partly attributed to endemic hookworm (Uncinaria sanguinis) infection. To further explore health outcomes of early hookworm elimination, a treatment trial was conducted at Seal Bay Conservation Park, South Australia, over consecutive lower and higher mortality breeding seasons (2019, 19.2%; 2020–1; 28.9%). Pups (n = 322) were stratified into two age cohorts (median 14 d and 24 d recruitment ages) and randomly assigned to treated (topical ivermectin 500  μg/kg) or control (untreated) groups. A younger prepatent cohort &lt;14 d old (median 10 d) was identified a posteriori. A seasonally independent growth benefit resulted from hookworm elimination across all age cohorts. The greatest relative improvements (bodyweight + 34.2%, standard length + 42.1%; p ≤ 0.001) occurred in the month post-treatment, in the youngest prepatent cohort. A significant benefit of lesser magnitude (bodyweight + 8.6–11.6%, standard length + 9.5–18.4%; p ≤ 0.033) persisted up to 3  months across all age cohorts – greatest in the youngest pups. Treatment resulted in immediate improvement in hematological measures of health – decreased anemia and inflammation severity (p ≤ 0.012). These results enhance our understanding of host–parasite–environment interactions within the context of hematological ontogenesis, confirm the seasonally independent benefits of hookworm disease intervention, and further inform conservation recommendations for this endangered species

Vers un diagnostic pastoral partagé : le cas de l'alpage de La Grande Cabane dans la réserve naturelle des hauts plateaux du Vercors

[Departement_IRSTEA]Territoires [TR1_IRSTEA]DTAM [Axe_IRSTEA]DTAM3-ECOPRAAvec le soutien financier de crédits incitatifs de la Zone-Atelier Alpes, il a été proposé de mettre en ½uvre un diagnostic pastoral partagé entre les acteurs impliqués dans la gestion et dans l’utilisation des espaces pastoraux de la Réserve naturelle des hauts plateaux du Vercors (RNHPV). La finalité de ce projet est de contribuer à mieux définir les rôles de chaque acteur et à leur (re)donner une place dans un réseau de dialogue sur la base d’un diagnostic pastoral partagé et d’un suivi concerté. La question de départ est la suivante : comment raisonner une nouvelle gestion pastorale visant à concilier gestion durable de la ressource pastorale et préservation des enjeux environnementaux ? Tout en tenant compte des travaux menés depuis plusieurs années sur la RNHPV, tant au plan scientifique qu’en matière de gestion opérationnelle, notre démarche a visé à tester sur un cas - l’alpage de la Grande Cabane - une nouvelle méthode de diagnostic pastoral, partagé entre les acteurs, s’appuyant sur une analyse fine des enjeux environnementaux et pastoraux en vue de hiérarchiser et localiser ces enjeux, de définir en commun des résultats à atteindre tout en tenant compte des contraintes d’utilisation et des objectifs propres aux différents acteurs

Alpages sentinelles dans le Parc national des Ecrins. Zoom sur l’alpage de Lanchâtra - Saint-Christophe en Oisans (Isère)

Fiche techniqueCette synthèse en 4 pages présente l'alpage de Lanchâtra dans le massif de l'Oisans qui fait partie du réseau Alpages sentinelles dans le Parc national des Ecrins. Sont abordés notamment la configuration de l'alpage, les végétations présentes sur l'alpage, la gestion pastorale, les conditions météo des années 2014 et 2015, l'évolution de la ressource pastorale et les pratiques pastorales, la conduite technique et les enjeux de l'exploitation agricole utilisatrice de l'alpage, suivie dans le cadre de ce réseau

Investigation of Weather Triggers Preceding Outbreaks of Acute Bovine Liver Disease in Australia

Acute bovine liver disease (ABLD) is a hepatic disease affecting cattle sporadically in southern Australia, characterised histologically by striking periportal hepatocellular necrosis. The cause of ABLD is unknown; however, the seasonality and acute presentation of outbreaks suggest mycotoxin involvement. We described the geographical and seasonal occurrence of ABLD reports from 2010 to 2020 in Victoria, Australia, and explored potential weather triggers preceding 26 outbreaks occurring across 23 properties using a case-crossover design. Outbreaks occurred most frequently in autumn/early winter and in herds located along the southern coastal plain of Victoria, and occasionally within the low-lying regions of the Great Dividing Range. Lactating adult dairy cattle represented the most reported cases. We observed a significant association between an increase in average daily dewpoint in the 15 days preceding an ABLD outbreak, suggesting that dew formation may be a key determinant for this disease. Our findings support the etiology of a potent hepatotoxic agent that requires moisture for proliferation and/or toxin production

Les alpages sentinelles : un dispositif original pour une nouvelle forme de gouvernance partagée face aux enjeux climatiques

International audienceThe Ecrins National Park organized a meeting of its Agriculture Commission to discuss repeated droughts and fears arising from the impact of alpine farming practices on high altitude environments. The alpine pasture was pronounced an area of shared challenges in terms of climate change, involving the co-responsibility of livestock farmers and the Park. It was also seen as an ideal area for observation and intervention based on cooperation. The ideas put forward led to the creation of the Sentinel Alpine Pastures programme.The ultimate aim of this programme is to anticipate the impact of climate events in order to ensure sustainable alpine pasture management. Studying modes of adaptation to events is part of a long-term approach to address the complex dynamics of climate change. We show how this approach, the information collection protocols and the data capitalization methods implemented aim to meet the requirements stemming from this current issue: involvement of all actors (livestock farmers and herdsmen, farming technicians, pastoral systems specialists, researchers and managers of protected areas), collective learning based on shared observations, and integration of an alpine pasture farms system. The programme works as a tool providing help with analysis and decision-making in relation to processes involving the climate, the environment, pastoral practices and livestock farming systems. The work collectives implementing it are also paving the way for new forms of governance in terms of the relations between pastoralism and local area stakeholders.En raison de sécheresses répétées et de craintes des conséquences de changements des pratiques pastorales sur les milieux d'altitude, le Parc national des Écrins a réuni sa Commission Agriculture : l'alpage a été reconnu comme un espace à enjeux partagés face au changement climatique, impliquant la coresponsabilité des éleveurs et du Parc, et comme un territoire privilégié d'observation et d'intervention en coopération. Cette posture est à la base de la conception du programme Alpages sentinelles.Sa finalité est d'anticiper l'impact des aléas climatiques afin d'assurer une gestion durable des alpages. L'étude des modes d'adaptation aux aléas s'inscrit dans une perspective de long terme face à la dynamique lourde du changement climatique. Nous montrons comment la démarche, les protocoles de recueil d'information et les formes de valorisation visent à répondre aux exigences suivantes, induites par cette problématique émergente : mobiliser l'ensemble des acteurs (éleveurs et bergers, techniciens agricoles, pastoralistes, chercheurs et gestionnaires d'espaces protégés), favoriser les apprentissages collectifs à partir de constats partagés, intégrer une approche du système alpage-exploitation. Les collectifs de travail qui font fonctionner cet outil d'aide à l'analyse et à la décision sur les processus qui se nouent entre climat, milieux, pratiques pastorales et systèmes d'élevage préfigurent aussi de nouvelles formes de gouvernance des relations entre pastoralisme et territoire

Variation in Toxoplasma gondii seroprevalence: effects of site, sex, species and behaviour between insular and mainland macropods

Context: Feral cats threaten wildlife conservation through a range of direct and indirect effects. However, most studies that have evaluated the impacts of feral cats on species of conservation significance have focussed on direct impacts such as predation; few studies have considered the indirect impacts of cat-borne disease. Toxoplasma gondii, a cat-borne parasite, causes both acute and latent disease in a range of wildlife species, and macropods are particularly susceptible. Kangaroo Island is Australia’s third largest island and supports a high density of feral cats and high seroprevalence of T. gondii in multiple species, relative to the mainland. This suggests that Kangaroo Island has a high environmental contamination with the parasite and a high risk of infection for other species.Aims: We aimed to describe T. gondii seroprevalence in culled and road-killed macropods, so as to assess the effects of island versus mainland location, sex, species and behaviour.Methods: Macropod sera were tested for T. gondii IgG antibodies using a commercially available modified agglutination test.Key results: The seroprevalence of T. gondii in culled western grey kangaroos (Macropus fuliginosus) was significantly higher on the island (20%, 11/54 positive) than on the mainland (0%, 0/61 positive). There was no difference in T. gondii seroprevalence between culled and road-killed (21%, 21/102 positive) kangaroos from the island. The seroprevalence of T. gondii was significantly higher in female (32%, 12/38 positive) than in male (13%, 8/60 positive) kangaroos, but we observed no sex effect in tammar wallabies (Macropus eugenii), and no effect of species.Conclusions: The higher T. gondii seroprevalence in insular macropods supports previous reports of higher T. gondii exposure in other Kangaroo Island fauna. The lack of difference in T. gondii seroprevalence between culled and road-killed kangaroos suggests that T. gondii-positive animals are not more vulnerable to road mortality, in contrast to that suggested previously.Implications: Our findings suggest greater potential adverse conservation impacts owing to toxoplasmosis on the island than on the mainland. In light of a recent study demonstrating higher cat abundance on the island than on the mainland, the higher observed T. gondii seroprevalence in insular macropods is likely to be a consequence of higher cat density

No Evidence of Toxoplasma Gondii Exposure in South Australian Koalas (Phascolarctos cinereus)

Infection with the cat-borne parasite Toxoplasma gondii has been detected in numerous Australian marsupials and can lead to severe disease (toxoplasmosis) in some cases. The seroprevalence of Toxoplasma on Kangaroo Island, South Australia has been reported to be higher than the South Australian mainland in macropods, cats, and sheep, suggesting an increased risk of infection on this island. However, Toxoplasma seroprevalence in small- and medium-sized terrestrial mammals was almost zero on the island and did not differ from that on the mainland. We surveyed Toxoplasma seroprevalence in koala (Phascolarctos cinereus) populations on the island and on the mainland and assessed their risk of infection and their role in the life cycle of Toxoplasma. All screened koalas from the island (n = 94) and the mainland (n = 63) were seronegative. This represents the largest Toxoplasma seroprevalence survey in this species and provided sufficient evidence to confidently demonstrate freedom from parasite exposure in both island and mainland populations at the time of the survey. Because koalas are extensively arboreal and predominately consume tree foliage, they appear to be at negligible risk of Toxoplasma infection. Furthermore, as koalas are rarely consumed by cats, we suggest that they have a minor role in the parasite's life cycle