Model of an aquaponic system for minimised water, energy and nitrogen requirements.

Water and nutrient savings can be established by coupling water streams between interacting processes. Wastewater from production processes contains nutrients like nitrogen (N), which can and should be recycled in order to meet future regulatory discharge demands. Optimisation of interacting water systems is a complex task. An effective way of understanding, analysing and optimising such systems is by applying mathematical models. The present modelling work aims at supporting the design of a nearly emission-free aquaculture and hydroponic system (aquaponics), thus contributing to sustainable production and to food security for the 21st century. Based on the model, a system that couples 40 m(3) fish tanks and a hydroponic system of 1,000 m(2) can produce 5 tons of tilapia and 75 tons of tomato yearly. The system requires energy to condense and recover evaporated water, for lighting and heating, adding up to 1.3 GJ/m(2) every year. In the suggested configuration, the fish can provide about 26% of the N required in a plant cycle. A coupling strategy that sends water from the fish to the plants in amounts proportional to the fish feed input, reduces the standard deviation of the NO3(-) level in the fish cycle by 35%.

Behaviour in a standardized assay, but not metabolic or growth rate, predicts behavioural variation in an adult aquatic top predator Esox lucius in the wild.

This study tested for links among behaviour, state and life-history variables as predicted by the pace-of-life hypothesis in adult pike Esox lucius. First, a standardized open-field behavioural assay was developed to assess individual behaviour of wild-captured adult E. lucius. Behaviour within the standardized assay predicted swimming behaviour in the lake, providing an ecological validation of the assay. There was no relationship between standardized behaviour and any of the life-history and state variables, including metabolism, body condition, juvenile growth rate and adult growth rate in contrast to predictions from the pace-of-life hypothesis. This study demonstrates that it is possible to assess ecologically relevant behavioural variation in a large-bodied top predator using a standard open-field assay, but it is noteworthy that this standardized behaviour is not systematically related to standard metabolism or growth.

Fatal interstitial lung disease associated with high erlotinib and metabolite levels. A case report and a review of the literature.

INTRODUCTION: Erlotinib is an agent in the class of oral epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors. Although this class of agents is considered to be relatively safe, the most serious, but rare, adverse reaction is drug-associated interstitial lung disease (ILD). This potentially fatal adverse reaction has been often described with gefitinib, but has been less well described for erlotinib. We here describe a case report of fatal interstitial lung disease in a Caucasian man associated with erlotinib and high erlotinib and metabolite plasma levels and discuss it in the context of all documented cases of erlotinib associated ILD. METHODS: Our case was described and for the literature review a Pubmed and Google Scholar search was conducted for cases of erlotinib associated ILD. The retrieved publications were screened for relevant literature. RESULTS: Besides our case, a total of 19 cases of erlotinib-associated ILD were found. Eleven out 19 cases had a fatal outcome and in only one case erlotinib plasma concentrations were measured and found to be high. CONCLUSION: Erlotinib-associated ILD is a rare, serious and often fatal adverse reaction. Most likely, the cause for erlotinib-associated ILD is multifactorial and high drug levels may be present in patients without serious adverse reactions. However, considering the pharmacology of EGFR inhibitors, high drug and metabolite levels may play a role and future studies are warranted to identify risk factors and to investigate the role of elevated levels of erlotinib and its metabolites in the development of pulmonary toxicity.

[Antiparasitic effects of peracetic acid (PAA) against infective stages (theronts) of white spot disease, Ichthyophthirius multifiliis in vitro]. / Antiparasitäre Effekte von Peressigsäure (PES) gegen infektiöse Stadien (Theronten) der Weisspünktchenkrankheit, Ichthyophthirius multifiliis in vitro.

White spot disease, caused by the protozoan parasite Ichthyophthirius multifiliis (I. multifiliis), invades nearly all fresh water fish species and causes huge economic losses. In Germany no protocide substance is legal for the treatment of I. multifilis. As an alternative substance the peracetic acid (PAA) was tested to treat the free invasive stage (theront) of the parasite. PAA concentrations of 0.3 ppm were able to kill all theronts in 120 min in our investigations. As a result of these investigations we recommend an interval-application of 0.3 to 0.5 ppm PAA for 30 to 150 min. This application should be prolonged for two life cycles of the parasite. Biotic parameters as e. g. fish species, and age as well as abiotic parameters as e. g. temperature, pH and organic load of the water could possibly influence the efficiency of the PAA application and should therefore be taken into account while picking the dosage and length of the PAA exposure.

Swimming efficiency and the influence of morphology on swimming costs in fishes.

Swimming performance is considered a main character determining survival in many aquatic animals. Body morphology highly influences the energetic costs and efficiency of swimming and sets general limits on a species capacity to use habitats and foods. For two cyprinid fishes with different morphological characteristics, carp (Cyprinus carpio L.) and roach (Rutilus rutilus (L.)), optimum swimming speeds (U(mc)) as well as total and net costs of transport (COT, NCOT) were determined to evaluate differences in their swimming efficiency. Costs of transport and optimum speeds proved to be allometric functions of fish mass. NCOT was higher but U(mc) was lower in carp, indicating a lower swimming efficiency compared to roach. The differences in swimming costs are attributed to the different ecological demands of the species and could partly be explained by their morphological characteristics. Body fineness ratios were used to quantify the influence of body shape on activity costs. This factor proved to be significantly different between the species, indicating a better streamlining in roach with values closer to the optimum body form for efficient swimming. Net swimming costs were directly related to fish morphology.

The effect of fasting and refeeding on temperature preference, activity and growth of roach, Rutilus rutilus.

Most fish species are regularly subjected to periods of starvation during which a reduction of energy turnover might be favourable for the animal. This reduction of energy flux may be achieved by changes in thermal behaviour and/or swimming activity. We investigated such behavioural changes during starvation and subsequent refeeding in roach, Rutilus rutilus, with respect to energetic benefits and growth maximisation. Roach, acclimated to a wide range of temperatures (4, 12, 20, 24, 27 and 30 °C), were fed to excess, subjected to 3 weeks of starvation and subsequently refed in order to determine the temperature dependence of feeding rates, growth rates and conversion efficiency (K1) under control conditions and during compensatory growth. When exposed to a thermal gradient, control animals preferentially selected a temperature of 26.8±0.9 °C, which is in the range of the optimal temperatures for feeding, growth and conversion efficiency. Starving fish showed a distinct circadian pattern of the mean selected temperature (MST). They migrated to cooler water in the dark (MSTdark=22.8±1.1 °C) but returned to warmer water during daytime. This behaviour may be regarded as a trade-off between the potentially higher food density in warmer water areas and the energetic benefit of selecting cooler water patches. The circadian pattern of MST was gradually abandoned upon refeeding and control values were reached again after 3 weeks. Energetically more effective than behavioural hypothermia was the reduction of swimming activity. During starvation, activity peaks were slightly lower than under control conditions and mean daily activity decreased by about 50%. Swimming velocity, however, was not affected by feeding regime. After a period of starvation fish showed compensatory growth at all temperatures, even below 12 °C, where these animals normally do not grow. This suggests that after a period of starvation the critical temperature for growth shifts to lower values.