Effects of salinity on growth characteristics and osmoregulation of juvenile cobia,Rachycentron canadum (Linnaeus 1766), reared in potassium‐amended inland saline groundwater

The suitability of inland saline groundwater as a medium to culture juvenile cobia, Rachycentron canadum, was assessed. In the first experiment, juvenile cobia stocked in raw (unamended) saline groundwater at salinities of 5, 10, and 15 g/L exhibited complete mortality after 108, 176, and 195 hr, respectively. The second experiment evaluated the rearing of juvenile cobia (mean weight ~9.23 ± 0.12 g) in potassium (K⁺)‐amended saline groundwater (100% K⁺ fortified) and reconstituted seawater at salinities of 5, 10, and 15 g/L to assess growth and osmoregulation in distinct culture media. Following 60 days of culture, all fish survived the experimental period. Final mean bodyweight of cobia reared in K⁺‐amended saline groundwater (103.2–115.8 g) and seawater (111.2–113.8 g) of different salinities did not vary significantly (p > .05). No differences (p > .05) were observed in specific growth rate, weight gain (%), and feed conversion ratio between treatment groups. Serum osmolality increased with salinity and was significantly higher (p < .05) for fish in K⁺‐amended saline groundwater (353–361 mOsmol/Kg) than in reconstituted seawater (319–332 mOsmol/Kg), although differences were not observed between salinities by water type. Cobia stocked in saline groundwater of different salinities were osmoregulating normally, and the higher values observed may be because of variations in ionic composition and other interfering ions in saline groundwater. Trial results suggest that juvenile cobia can achieve optimal growth in K⁺‐amended saline groundwater of low and intermediate salinities.     

BMC ecology image competition 2017: the winning images

For the fifth year, BMC Ecology is proud to present the winning images from our annual image competition. The 2017 edition received entries by talented shutterbug-ecologists from across the world, showcasing research that is increasing our understanding of ecosystems worldwide and the beauty and diversity of life on our planet. In this editorial we showcase the winning images, as chosen by our Editorial Board and guest judge Chris Darimont, as well as our selection of highly commended images. Enjoy!     

Replacement of fish oil in plant‐based diets for Pacific white shrimp,Litopenaeus vannamei,by stearine fish oil and palm oil

Stearine fish oil (SFO) and palm oil (PO) have emerged as promising alternatives for the replacement of fish oil (FO) in aquafeeds. This study evaluated the replacement of FO with alternative oils in practical diets for Litopenaeus vannamei. In a clear brackish water study (14.1 g/L) utilizing shrimp (0.29 ± 0.02 g, initial weight), FO was replaced by SFO at inclusion ratios of 100:0, 75:25, 50:50, 25:75, and 0:100 (FO:SFO) and PO as 90% of FO. After 55 days, no significant differences (p < 0.05) in final weight, growth, or survival of shrimp were observed. A second trial (8 weeks) in low‐salinity water (2.1 g/L) with shrimp (0.92 ± 0.02 g, initial weight) evaluated diets with 100% FO, 100% SFO, 90% PO, 90% soybean oil (SO), or 90% flaxseed oil (FXO) as a replacement for FO and four commercially produced diets with 2% of FO, SO, PO, or FXO. One treatment received half rations of the commercial FO diet, and one treatment was based entirely on natural productivity. Results show that the fatty acid profiles of the tail muscle conformed to the lipids of the feed, and highly unsaturated fatty acids (HUFAs) were preserved. Following 8 weeks of culture, there were no significant differences in production performance.     

Using webinars to extend the reach of soil learning in New South Wales: A first look

Increasingly knowledge is shared using new web‐based channels. The use of these channels is relatively new in the realm of soil science. However, they may prove to be very useful for connecting time‐poor, geographically dispersed audiences in an efficient and cost‐effective way. There has been limited study of this form of knowledge sharing for natural science (let alone soil science). In New South Wales (NSW), Australia, the NSW Department of Primary Industries (NSW DPI) has coordinated the Soil Network of Knowledge (SNoK) monthly webinar over 3 years, with over 40 webinars targeting an audience of next users of soil information. Aggregated data collected from these webinars indicated that the majority of information is used for professional development by participants. Whether this will eventually lead to on‐ground practice change because of the improved professional and technical knowledge of participants is still a moot point and will require further investigation over time. The information collected on attendance and participation showed that webinars are a good way to connect with some target audiences such as other government bodies that have a historical relationship with NSW DPI. However, other target audiences that NSW DPI has always found difficulty in engaging, such as private advisers, require more active overtures to drive participation. The growing subscriber base is encouraging.     

Fractionated oral dosing and its effect on cyclophosphamide pharmacokinetics in dogs with high-grade multicentric lymphoma

Cyclophosphamide (CP) is an alkylating agent commonly included in multi-drug treatment protocols for canine cancer. As a prodrug, CP requires hepatic metabolism for activation to the intermediate compound 4-hydroxycyclophosphamide (4-OHCP) which then spontaneously forms alkylating phosphoramide mustard. CP is frequently administered in a fractionated manner, with the total dose given over multiple days. CP is reported to cause auto-induction of metabolism in humans, with faster CP clearance and relatively increased 4-OHCP formation following fractionated versus bolus dosing, however canine pharmacokinetic studies of CP dose fractionation are lacking. The study objective was to evaluate the pharmacokinetics of fractionated oral CP dosing at a dose of 200–250 mg/m² over 3 to 4 days in a prospectively identified population of cancer-bearing dogs. Plasma concentrations of CP and 4-OHCP were measured by ultra-high performance liquid chromatography tandem-mass spectrometry in eight dogs following the first and last doses to assess for auto-induction of CP metabolism. No significant difference in the rate of CP elimination between first and last doses were detected (0.73 ± 0.46 vs. 1.22 ± 0.5 h⁻¹; p = .125). Additionally, no significant difference in dose-normalized 4-OHCP exposure was identified between first and last doses (5.9 ± 2.1 vs. 7.9 ± 6.4 h × ng/ml; p = .936). These results suggest that fractionated dosing may not increase exposure to the active metabolite of CP in dogs as it does in humans. As such, standard bolus dosing and fractionated dosing may be equivalent in terms of bio-activation of CP in dogs administered a dose of 200–250 mg/m².     

Does streptobacillary arthritis reduce house mouse population density,activity and damage to sorghum crops?

An experiment to examine the effect of streptobacillary arthritis on mouse populations was conducted in maturing sorghum crops in mouse-proofed pens. There were three treatment pens and three control pens in which mice with and without clinical signs of streptobacillary arthritis were introduced, respectively. A constant mouse density (533 mice ha⁻¹) was introduced to the pens by releasing 12 mice in each pen. The sex ratio of introduced mice was also constant by releasing in each pen nine males and three females. Mean track index was lower in treatment pens than in control pens, indicating that streptobacillary arthritis reduced the activity of mice. However, this was not translated into a reduction in other population responses. Mean mouse density at harvest, percentage of female pregnant at harvest, yield loss caused by mice and a feeding index (oil card index) did not differ significantly between treatment and control groups. A plausible explanation for these findings was that mice with the clinical signs might be less active but were able to consume as much grains as mice without the clinical signs because food was in abundant supply.     

A Fish of Weedy Waters: Golden Shiner Biology and Culture

The golden shiner, Notemigonus crysoleucas, is a major bait and forage fish species in the USA. Farmers produce millions of golden shiners annually that are distributed live, many across state boundaries. Native over much of the eastern and central USA, this species is often present but rarely abundant in natural systems, as fish density is apparently controlled by predation rather than by food resources. Aquaculture of the golden shiner is a century‐old practice and culture methods have evolved over time, resulting in today's farm‐raised, certified specific pathogen– and aquatic nuisance species–free baitfish. Federal and state agencies and universities have a long history of developing culture methods and promoting baitfish culture to replace the indiscriminate and wasteful harvest of fish from natural waters. Despite advances in culture methods and the advantages of a farm‐raised species produced under controlled and biosecure conditions, golden shiner farming is only marginally profitable and remaining farmers survive on farm equity and increased market share from others exiting the business. Ironically, increasing regulations and restrictions leading to a reduction in the supply of farm‐raised baitfish could drive anglers back to harvesting bait from natural waters, the very concern that initiated government support for baitfish culture a century ago.     

Migration‐affected change and vulnerability in rural Vanuatu

Migration is increasingly being promoted as a possible adaptive response to risks associated with climate change and other stresses. While migration may present an adaptation pathway in certain contexts, existing research fails to consider the ways in which migration could contribute to vulnerability in sending communities. This paper examines the impact of migration‐affected change on local vulnerability in Lamen Bay, Vanuatu. Qualitative methods, including interviews and focus groups with 58 individuals, were used to determine how migration interacts with the multiple stressors faced by the community. The results show that migration is likely to contribute to vulnerability in already vulnerable communities. In Lamen Bay, migration affects a number of contextual factors that influence exposure and the capacity to respond to change, including labour supply, food security, migrant attitudes, underdevelopment and institutional viability. These results suggest that development policy in Vanuatu needs to address existing vulnerabilities while offering the opportunity to migrate.     

Segregation distortion in doubled haploid lines of barley (Hordeum vulgare L.) detected by simple sequence repeat (SSR) markers

A total of 147 simple sequence repeat (SSR) markers (including86 barley and 61 wheat microsatellite markers) were tested for their segregation in a doubled haploid (DH) and an F₂ population of barley. The DH population consisted of 71 doubled haploid lines, developed from F₁ plants of a cross between Tadmor and WI2291using isolated microspore culture technique. A genetic linkage map consisting of 43 microsatellite markers was constructed using the DH population. Particularly on chromosome 4H microsatellite markers showed distorted segregation ratios. Segregation of DH lines based on molecular markers were compared with segregation of 92 F₂ lines from the same cross. The proportion of loci deviating from the expected monogenic segregation ratios in the DH population was significantly higher (19/43loci, 44%) than in the F₂ population (7/43 loci, 16%). The deviation was biased towards the WI2291 parent alleles. In line with this observation, WI2291 was found to perform better than Tadmor in regenerating green plantlets with the isolated microspore-culture technique. This revised version was published online in July 2006 with corrections to the Cover Date.     

Levels and incidences of pesticide residues in various foods and animal feeds analyzed by the Luke multiresidue methodology for fiscal years 1982-1986

During a 5 year period from 1982 to 1986, the FDA Los Angeles District Laboratory analyzed 19,851 samples of domestic and imported food and feed commodities for pesticide residues. A single, rapid, multiresidue method was used. The resultant data have been compiled showing the commodities sampled and the identity and range of levels of pesticide residues detected, including an indication of those residue findings that did not comply with U.S. federal tolerance levels. The residue data presented should not be viewed as being representative of the U.S. food supply; rather, the results are indicative of a surveillance- and compliance-oriented sampling of various food shipments collected by the Los Angeles District.