Forecasting the Genetic Impacts of Net Pen Failures on Gulf of Mexico Cobia Populations Using Individual‐based Model Simulations

Offshore net pen fish farming provides a cost‐efficient means for production of marine finfish, and there is great interest in development of net pen operations in domestic waters. However, there are concerns over the possible genetic and ecological impacts that escaped fish may have on wild populations. We used individual‐based simulations, with parameter values informed by life history and genetic data, to investigate the short‐term (50 yr) impacts of net pen failures on the genetic composition of cobia, Rachycentron canadum, stocks in the Gulf of Mexico. Higher net pen failure rates resulted in greater genetic impacts on the wild population. Additionally, the use of more genetically differentiated source populations led to larger influxes of non‐native alleles and greater temporal genetic change in the population as a result of net pen failure. Our results highlight the importance of considering the appropriate source population for broodstock collection in net pen aquaculture systems and help to provide a general set of best management practices for broodstock selection and maintenance in net pen aquaculture operations. A thorough understanding of the genetic diversity, stock structure, and population demography of target species is important to determine the impact escapees can have on wild populations.     

Soil protection for a sustainable future: options for a soil monitoring network for Ireland

The increased recognition of the importance of soil is reflected in the UN Post‐2015 Development Agenda with sustainable development goals that directly and indirectly relate to soil quality and protection. Despite a lack of legally binding legislation for soil protection, the European Commission remains committed to the objective of soil protection. However, the achievement of a legally binding framework for soil protection relies on the implementation of a soil monitoring network (SMN) that can detect changes to soil quality over time. As beneficiaries do not pay for the provision of soil information, the options for soil monitoring are limited. The use of existing data sets should be considered first. Using Ireland as an example, this research explored the opportunities for a SMN for Ireland considering three existing national data sets. The options for a SMN are considered in terms of their spatial and stratified distribution, the parameters to be measured and an economic analysis of the options proposed. This research finds that for Ireland, either a 10 or a 16 km² grid interval stratified by land use and drainage class offers the best potential in relation to the spatial distribution of existing data sets to reflect local data at a national level. With existing data, the stratified SIS data using the 16 km² grid offers the best value for money, with baseline costs for analysis, excluding field costs, of between €706 481 and €2.8 million. Acknowledging the impossibility of measuring all parameters with ideal frequency, this study proposes a two‐tier system for optimized monitoring frequency. Parameters must anticipate future policy requirements. Finally, the implementation of a SMN must be accompanied by standardized methods, defined thresholds and action mandates to maintain soil quality within allowable limits.     

Choline supplementation increased total body lipid gain,while surplus methionine improved growth and amino acid retention in adult Atlantic salmon (Salmo salar)

Methionine–choline‐deficient (MCD) mammals are known to accumulate liver TAG probably due to phosphatidylcholine (PC) deficiency and thus assembly of VLDL and transport of lipids from liver to peripheral organs. To assess whether supplementation of choline could spare methionine and secure a healthy liver metabolism, by reducing the endogenous PC synthesis without interfering with lipid transport and distribution, Atlantic salmon with initial BW of 700 g were fed adequate (1.9 g Met/16 gN) or surplus methionine (2.5 g Met/16 gN) diets of which were supplemented with choline or not for a period of 19 weeks. Fish fed the low‐methionine diets had reduced growth (p = .013) due to reduced protein gain (p = .007), while lipid gain slightly improved in fish fed the choline‐supplemented diets (p = .047). Also, feed conversion improved when fed surplus methionine (p < .001), while choline supplementation had no impact on feed conversion. No interaction between choline and methionine on growth performance or retention existed. Phospholipid status in liver and muscle was not affected by treatments, and no liver TAG accumulation occurred at the methionine levels used. Gene expression of ApoB100 necessary for assembling VLDL or pemt necessary for endogenous PC synthesis was unaffected by treatments. Capacity of methylation (MAT, BHMT) within the liver was not affected by treatment nor was the gene expression of enzymes in liver transsulfuration (CBS or CDO). Methionine status within liver was unaffected by treatments, while free methionine reduced in those fish fed the low‐methionine diets in muscle and plasma. Cystathionine and taurine were elevated when fed surplus methionine. Choline supplementation had no impact on sulphur amino acid metabolites in either tissue. Neither did choline supplementation improve TAG mobilization from liver to muscle. To conclude, choline does not improve endogenous phospholipid synthesis or transport of TAG from liver to muscle depot when added to diets containing 1.9 g Met/16 gN, while surplus methionine improved growth and protein retention, indicating that 1.9 g Met/16 gN is enough to support a healthy liver metabolism, but too low to support muscle protein deposition in adult salmon fed high plant protein diets for longer periods of time.     

A fluorescence‐based assay for in vitro screening of Saprolegnia inhibitors

The incidence of fish pathogenic oomycetes, Saprolegnia, has increased significantly in aquaculture since the ban of malachite green. For the efficient characterization of anti‐Saprolegnia therapeutics, simple accurate methods are required. However, the current screening methods are limited by time, and none of them are confirming the viability of treated spores or hyphae. In this study, a modified fluorescence‐based assay for the in vitro screening of Saprolegnia inhibitors has been developed. This method involves the use of FUN‐1 viability dye combined with calcofluor white M2R, and is based on the formation of orange‐red cylindrical intravacuolar structures (CIVS) in metabolically active spores, hyphae and biofilms. Heat‐killed and bronopol‐treated Saprolegnia spores, hyphae and biofilms exhibited diffuse bright green fluorescence which confirms complete loss of viability. For boric acid‐treated spores, no germination was observed. However, tiny CIVS were observed in 50% of treated spores which indicated reduction in their viability. Our results proved that FUN‐1 dye is an efficient tool to distinguish between live and dead Saprolegnia spores, hyphae and biofilms and to monitor the change in Saprolegnia viability during qualitative evaluation of potential anti‐Saprolegnia compounds.     

Can water disinfection prevent the transmission of infectious koi herpesvirus to naïve carp? – a case report

Hygienic measures such as disinfection are important tools for the maintenance of fish health in aquaculture. While little information is available on the disinfection of water intended for fish containment, Huwa‐San^®, a disinfectant used in food and water industries, was used for daily treatment at concentrations of approximately 60 ppm over a total period of 3 months (experiment 1) with a 3‐week treatment‐free interval after 2 months (experiment 2). During this period, koi herpesvirus (KHV) was added to the water of two aquaria, one used as a normal contact control, the other one receiving daily water disinfectant treatments that prevented KHV infection of carp. In the second experiment, Huwa‐San^® treatment was interrupted and KHV infection was prevalent. However, when naïve fish were introduced to the same aquarium after re‐application of disinfectant, KHV could not be detected in those naïve fish. Whilst KHV could not be detected in samples where disinfectant had been applied, it was present in samples of naïve fish cohabiting with infection contact control animals which had undergone no disinfectant treatment over experiments 1 and 2. The results presented here show that water treatment with a disinfectant may prevent transmission of infectious KHV to naïve carp cohabited with infected carp.     

Resource Use Assessment of Shrimp,Litopenaeus vannamei and Penaeus monodon,Production in Thailand and Vietnam

Resource use was investigated at 34 Litopenaeus vannamei and five Penaeus monodon farms in Thailand and 30 L. vannamei and 24 P. monodon farms in Vietnam. Farms varied in water surface areas for production, reservoirs, canals, and settling basins; in pond size and depth; and in water management, stocking density, feeding rate, amendment input, aeration rate, crop duration, and crops per year. Production of L. vannamei averaged 17.3 and 10.9 m.t./ha/yr, and feed conversion ratio averaged 1.49 and 1.33 in Thailand and Vietnam, respectively. On average, production of 1 m.t. of L. vannamei required 0.58 ha land, 5,400 m³ water, 60 GJ energy, and 1218 kg wildfish in Thailand and 1.76 ha land, 15,100 m³ water, 33.7 GJ energy, and 1264 kg wildfish in Vietnam. Resource use per metric ton of shrimp declined with greater production intensity. In Thailand, P. monodon was produced at 0.2–0.4 m.t./ha/yr, with no inputs but water and postlarvae. In Vietnam, P. monodon production averaged 3.60 m.t./ha/yr. Production of 1 m.t. of P. monodon required 0.80 ha land, 36,000 m³ water, 47.8 GJ energy, and 1180 kg wildfish, and resource use per ton production declined with increasing production intensity.     

An outbreak of Shewanella putrefaciens group in wild eels Anguilla anguilla L. favoured by hypoxic aquatic environments

Microbiological analyses were conducted on wild eels from the L′Albufera Lake (Spain). A total of 174 individuals were collected in two surveys (i.e. year 2008 and autumn–winter 2014) among those caught by local fishermen into the lagoon. The prevalence of Shewanella putrefaciens group was 1.7% in 2008 and rose above 32% in 2014. It was due to an outbreak of shewanellosis that presented a morbidity rate of 64%. S. putrefaciens group strains were isolated as pure cultures from the sick eels that showed white ulcers surrounded by a reddish inflammation, damage of the mouth, extensive skin discoloration, exophthalmia, ascites and bad odour. The S. putrefaciens group was recovered from freshwater samples taken at the L′Albufera system, along autumn–winter 2015. Its counts significantly increased in freshwater parallel to hypoxia and temperature rising. Shewanellae strains were identified as S. putrefaciens and S. xiamenensis by 16S rRNA gene sequencing. These isolates recovered from sick eels or freshwater were virulent for European eel by IP challenge (LD₅₀ 10⁶ CFU g^?1 body weight). They also caused 30–38% cumulative mortality, in European eels challenged by a 2‐h bath (10⁷ CFU mL^?1). These results suggest that shewanellosis could be transmitted through water highlighting the fact that hypoxic conditions increase this bacterium levels in water.     

Transient bilateral blindness associated with presumptive idiopathic pachymeningitis in a 22-year-old Irish Sport Horse

A 22-year-old Irish Sport Horse presented following a period of bilateral blindness with subsequent spontaneous resolution. Brain magnetic resonance imaging (MRI) demonstrated features consistent with pachymeningitis. Cerebrospinal fluid (CSF) analysis revealed increased numbers of basophils, suggestive of an immunologic or neoplastic aetiology. It was suspected that the enlarged meninges led to compression of the optic nerves in the optic canals, causing bilateral blindness. Initial spontaneous remission, as seen in this case, has been reported in human patients with this condition. Pachymeningitis should be considered as a possible cause of cranial nerve deficits, including bilateral and unilateral blindness, in horses.     

Projecting the suitability of global and local habitats for myrtle rust (Austropuccinia psidii) using model consensus

Myrtle rust (caused by Austropuccinia psidii) affects more than 500 known host species in the Myrtaceae family. Three different modelling approaches (CLIMEX, MaxEnt and Multi-Model Framework) were used to project the habitat suitability for myrtle rust at both global and local scales. Current data on the global occurrence of myrtle rust were collected from online literature and expert solicitation. Long-term averages of climate data (1960–1990) were sourced from WorldClim and CliMond websites. Recent reports of myrtle rust in New Zealand were used for validation of model outputs but not in model training and testing. The model outputs were combined into a consensus model to identify localities projected to be suitable for myrtle rust according to two or three models (hotspots). In addition to the locations where the pathogen is currently present, all models successfully projected independent occurrence data in New Zealand suitable for establishment of the pathogen. Climate suitability for the pathogen was primarily related to temperature followed by rainfall in MaxEnt and the CLIMEX model. The results confirmed the optimum temperature range of this pathogen in the literature (15–25 °C). Additional analysis of the precipitation variables indicated that excessive rain (more than 2000 mm in warmest quarter of the year) combined with high temperatures (>30 °C) constrain pathogen establishment. The results of the current study can be useful for countries such as New Zealand, China, South Africa and Singapore where the pathogen has not fully spread or established.     

Metabolic rates from Bluntnose minnow (Pimephales notatus) populations at lower latitudes are more sensitive to changes in temperature than populations at higher latitudes

Predicting the potential effects of changes in climate on freshwater species requires an understanding of the relationships between physiological traits and environmental conditions among populations. While water temperature is a primary factor regulating metabolic rates in freshwater ectotherms, how metabolic rates vary across the species range is unclear. In addition, photoperiod has also been hypothesised to influence metabolic rates in freshwater taxa based on seasonal changes in activity rates. Using an experimental approach, we investigated whether variation in routine metabolic rate (RMR) and sensitivity of RMR to changes in temperature are correlated with local thermal regimes, photoperiods and body mass among ten populations across the geographic range of the Bluntnose minnow (Pimephales notatus), a North American freshwater fish species. Routine metabolic rate data were collected from populations acclimatised to three temperature treatments (9, 18 and 27°C) and correlated with water temperature and photoperiod estimates at collection locations for each population. Routine metabolic rate was negatively correlated with minimum photoperiod at 9°C, negatively correlated with weekly high temperature at 18°C and positively correlated with weekly high temperature at 27°C. Body mass was also a predictor of RMR at each temperature treatment. Thermal sensitivity of RMR was positively correlated with weekly high temperature, indicating that individuals from warmer low latitude populations experienced greater sensitivity of RMR to changes in temperature than individuals from cooler high latitude populations. These results indicate differential responses among populations to variation in temperature and suggest the importance of recognising this variation when characterising responses of freshwater taxa to increases in water temperature.