Biochemical and physiological studies on the reproductive hormones of the dogfish (Scyliorhinus canicula L.)

This thesis was submitted for the degree of Doctor of Philosophy and awarded by the University of Wales.Biochemical and Physiological studies on the reproductive hormones of the dogfish (Scyliorhinus canicula L.

Intuitive resources: ‘It’s like having you at home helping us’

A recent report from the EDUCAUSE Centre for Applied Research highlights that students are integrating smart technologies and web-based tools into their academic experience (ECAR, 2011). With this in mind, the Intuitive Resources project at Falmouth University created and evaluated the use of High Definition (HD) learning videos. These videos may be accessed by mobile/smartphone technologies and have been designed with close consideration of curriculum delivery and assessment in studio-based projects

Exposure of female juvenile rainbow trout to alkylphenolic compounds results in modifications to growth and ovosomatic index

The alkylphenol ethoxylates (APEOs) are a major group of non-ionic surfactants. Biodegradation of these compounds is incomplete during sewage treatment, thus they are ubiquitous aquatic pollutants. All the main degradation products of APEOs have recently been demonstrated to have estrogenic properties in vitro, but their effects in vivo remain to be established. In this study, female juvenile rainbow trout (Oncorhynchus mykiss Walbaum) were exposed to octylphenol (OP), nonylphenol (NP), nonylphenol diethoxylate (NP2EO) and nonylphenol mono-carboxylic acid (NP1EC) at environmentally relevant concentrations (Experiment 1: 1, 10 and 50 ug/L; Experiment 2: 1, 10 and 30 ug/L). Exposure to APEO’s commenced at hatch (day 0) and was terminated on day 22 (Expt. 1) or day 35 (Expt. 2). Body weight and fork length of representative samples of fish from each treatment group were recorded at intervals up to 108 days (Expt. 1) or 466 days (Expt. 2). In Experiment 1, significant differences in size of the exposed fish, related to treatment, were still apparent on day 108, 86 days after withdrawal of the treatments. These observations were confirmed during Experiment 2, in which significant changes in body weight and fork length as a consequence of exposure to the compounds were observed approximately 15 days after exposure was terminated. These differences were sustained for at least 466 days in the case of NP and NP1EC. In addition, the ovosomatic index (OSI) of fish exposed to NP and NP1EC was significantly affected by the treatment. Survival of fish in the natural environment is strongly influenced by body size, and an appropriate OSI is a crucial factor in successful reproduction. Therefore, exposure of natural populations of fish to these chemicals at concentrations currently measurable in the aquatic environment may have an impact on the performance of those populations

A rational approach to selecting and ranking some pharmaceuticals of concern for the aquatic environment and their relative importance compared with other chemicals

Aquatic organisms can be exposed to thousands of chemicals discharged by the human population. Many of these chemicals are considered disruptive to aquatic wildlife; the literature on the impacts of these chemicals grows daily. However, since time and resources are not infinite, we must focus on the chemicals which represent the greatest threat. One group of chemicals of increasing concern is the pharmaceuticals, where the struggle is to identify which of them represent the greatest threat. In the present study, we compiled a list of 12 pharmaceuticals based on scoring the prevalence of different compounds from previous prioritization reviews. These included rankings based on prescription data, environmental concentrations, PEC/PNEC ratios, PBT, and fish plasma model approaches. The most frequently cited were diclofenac, paracetamol, ibuprofen, carbamazepine, naproxen, atenolol, ethinylestradiol, aspirin, fluoxetine, propranolol, metoprolol and sulfamethoxazole. For each pharmaceutical, literature on effect concentrations was compiled and compared with river concentrations in the UK. The pharmaceuticals were ranked on the degree of difference between the median effect and median river concentrations. EE2 was ranked as the highest concern, followed by fluoxetine, propranolol and paracetamol. The relative risk of these pharmaceuticals was compared with those of metals and some persistent organic pollutants. Pharmaceuticals appear to be less of a threat to aquatic organisms than some metals (Cu, Al, Zn) and triclosan using this ranking approac

Putting pharmaceuticals into the wider context of challenges to fish populations in rivers

The natural range of fish species in our rivers is related to flow, elevation, temperature, local habitat and connectivity. For over 2000 years, humans have altered to varying degrees the river habitat. In the past 200 years, we added to the environmental disruption by discharging poorly treated sewage, nutrients and industrial waste into our rivers. For many rivers, the low point arrived during the period of 1950s–1970s, when rapid economic development overrode environmental concerns and dissolved oxygen concentrations dropped to zero. In these more enlightened times, gross river pollution is a thing of the past in the Developed World. However, persistent legacy chemical contaminants can be found in fish long after their discharge ceased. Changes in habitat quality and morphology caused and continue to cause the disappearance of fish species. The range of fish stressors has now increased as temperatures rise, and non-native fish introductions bring new diseases. The threat from pharmaceuticals to fish populations remains hypothetical, and no studies have yet linked change in fish populations to exposure

Assessing the concentrations and risks of toxicity from the antibiotics ciprofloxacin, sulfamethoxazole, trimethoprim and erythromycin in European rivers

This study evaluated the potential concentrations of four antibiotics: ciprofloxacin (CIP), sulfamethoxazole (SUF), trimethoprim (TRI) and erythromycin (ERY) throughout the rivers of Europe. This involved reviewing national consumption rates together with assessing excretion and sewage treatment removal rates. From this information, it was possible to construct best, expected and worst case scenarios for the discharge of these antibiotics into rivers. Consumption data showed surprising variations, up to 200-fold in the popularity of different antibiotics across different European nations. Using the water resources model GWAVA which has a spatial resolution of approximately 6 × 9 km, river water concentrations throughout Europe were predicted based on 31-year climate data. The modelled antibiotic concentrations were within the range of measurements reported previously in European effluents and rivers. With the expected scenario, the predicted annual-average antibiotic concentrations ranged between 0 and 10 ng/L for 90% by length of surface waters. In the worst case scenario concentrations could reach between 0.1 and 1 μg/L at the most exposed locations. As both predicted and observed sewage effluent concentrations were below reported effect levels for the most sensitive aquatic wildlife, no direct toxicity in rivers is expected. Predicted river concentrations for CIP and ERY were closest to effect levels in wildlife, followed by SUF which was 2–3 orders of magnitude lower. TRI appeared to be of the least concern with around 6 orders of magnitude difference between predicted and effect levels. However, mixture toxicity may elevate this risk and antibiotic levels of 0.1–1 μg/L in hotspots may contribute to local environmental antibiotic resistance in microorganisms

Learning from the past and considering the future of chemicals in the environment

Knowledge of the hazards and associated risks from chemicals discharged to the environment has grown considerably over the past 40 years. This improving awareness stems from advances in our ability to measure chemicals at low environmental concentrations, recognition of a range of effects on organisms, and a worldwide growth in expertise. Environmental scientists and companies have learned from the experiences of the past; in theory, the next generation of chemicals will cause less acute toxicity and be less environmentally persistent and bioaccumulative. However, researchers still struggle to establish whether the nonlethal effects associated with some modern chemicals and substances will have serious consequences for wildlife. Obtaining the resources to address issues associated with chemicals in the environment remains a challenge

Baseline data from the EDCAT research programme on oestrogens and fish populations

The EDCAT programme now has over two year’s baseline data on the chemistry and fish biology of an English river, the Ray, which receives oestrogenic sewage effluent from the city of Swindon. It has developed models which predict oestrogen concentrations in the river throughout the year, and has successfully corroborated these with data on oestrogenic substances, in vitro oestrogenic activity, and non-oestrogenic contaminants. It has also gathered data on the dynamics and oestrogenic responses of stickleback populations in the river during a period when the sewage discharge received both normal dilution, and high dilution from unusually large river flows. Finally, breeding experiments with wild intersex roach have been conducted in which the breeding success of each individual has been tracked by microsatellite analysis of offspring. The Swindon (Rodbourne) sewage treatment plant has now been upgraded with granular activated carbon filtration technology to remove oestrogens, and future work of the EDCAT programme will monitor the rate of recovery of fish populations in the River Ray