Soil Chemical Analysis

Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

/pdf/climate-change-2007-the-physical-science-basis-1x93ttz9jt.pdf

Climate Change 2007: The Physical Science Basis.

Continued growth and intensi¢cation of aquaculture production depends upon the development of sustainable protein sources to replace ¢sh meal in aquafeeds. This document reviews various plant feedstuis, which currently are or potentially may be incorporated into aquafeeds to support the sustainable production of various ¢sh species in aquaculture. The plant feedstuis considered include oilseeds, legumes and cereal grains, which traditionally have been used as protein or energy concentrates as well as novel products developed through various processing technologies. The nutritional composition of these various feedstuis are considered along with the presence of any bioactive compounds that may positively or negatively aiect the target organism. Lipid composition of these feedstuis is not speci¢cally considered although it is recognized that incorporating lipid supplements in aquafeeds to achieve proper fatty acid pro¢les to meet the metabolic requirements of ¢sh and maximize human health bene¢ts are important aspects. Speci¢c strategies and techniques to optimize the nutritional composition of plant feedstuis and limit potentially adverse eiects of bioactive compounds are also described. Such information will provide a foundation for developing strategic research plans for increasing the use of plant feedstuis in aquaculture to reduce dependence of animal feedstuis and thereby enhance the sustainability of aquaculture.

/pdf/expanding-the-utilization-of-sustainable-plant-products-in-4l188wibvf.pdf

Expanding the utilization of sustainable plant products in aquafeeds: a review

Communities of microscopic plant life, or phytoplankton, dominate the Earth's aquatic ecosystems. This important new book by Colin Reynolds covers the adaptations, physiology and population dynamics of phytoplankton communities in lakes and rivers and oceans. It provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and in addition reviews recent advances in community ecology, developing an appreciation of assembly processes, co-existence and competition, disturbance and diversity. Although focussed on one group of organisms, the book develops many concepts relevant to ecology in the broadest sense, and as such will appeal to graduate students and researchers in ecology, limnology and oceanography.

/pdf/the-ecology-of-phytoplankton-4ev70n3jsq.pdf

The Ecology of Phytoplankton

The repeatability of behaviour: a meta-analysis.

The effect of feeding level on growth and survival of jaguar guapote (Cichlasoma managuense) larvae fed Artemia nauplii

As a consequence of water re-use and high stocking densities, Recirculating Aquaculture Systems (RAS) may lead to an accumulation of substances released by the fish into the water, e.g. cortisol and alarm pheromones. This study investigated the effect of stressing fish on the feeding motivation of other fish not subjected to stress but sharing the same water of stressed fish. Two identical RAS were used (operated at 30 L kg feed-1 day-1) and contained grouped (stressed fish) and individually (receiving water from stressed fish) housed Nile tilapia. A stress test was applied in grouped housed fish on days 17 and 55. Feeding behaviour (intake and latency) was recorded in the individually housed fish 3 days before, during and 3 days after the stress test. The results showed no effect on feeding behaviour in fish receiving the water from stressed fish. These results could be a consequence of insufficient cortisol/alarm cues' release by the stressed fish into the water or inactivity of such substances, either due to a trapping effect of humic acids or due to degradation in the nitrification and denitrification processes. Future research is needed to clarify how these processes may affect the water concentration of cortisol and alarm pheromones and should be extended by measuring other behavioural and physiological traits

Stressing fish in Recirculating Aquaculture Systems (RAS): does stress induced in one group of fish affect the feeding motivation of other fish sharing the same RAS

The bioconcentration of waterborne geosmin in rainbow trout, Oncorhynchus mykiss (Waldbaum) was assessed. Fifty rainbow trout with a mean (SD) weight of 226.6 (29.0) g and lipid content of 6.2 (0.6) % (w/w) were exposed to geosmin in static water for 0, 2, 4, 6, 8, 12, 24, 36, 48 and 120 hr, with one tank containing five fish for eac h exposure period. Geosmin concentrations were measured in fish tissue and water samples collected over time. With time the geosmin concentration in the fish increased and decreased in the water. However, the total absolute amount of geosmin in the system declined over time which could be explained by induction of biotransformation. This is in accordance with the decreasing lipid normalized geosmin levels in the liver compared with the liver-free carcass. Geosmin distribution within rainbow trout clearly is not exclusively governed by the lipid content of tissues. In vivo geosmin bioconcentration in rainbow trout is slower and the body burden reached is lower than the generally accepted theoretical model predicts.

/pdf/experimental-validation-of-geosmin-uptake-in-rainbow-trout-56ujhlekwj.pdf

Experimental validation of geosmin uptake in rainbow trout, Oncorhynchus mykiss (Waldbaum) suggests biotransformation

https://onlinelibrary.wiley.com/doi/pdf/10.1111/faf.12606

Environmental requirements and heterogeneity of rheophilic fish nursery habitats in European lowland rivers: Current insights and future challenges

The influence of dietary cation-anion difference (CAD, Na K - Cl, mEq kg1) on energy metabolism and nitrogen losses in juvenile African catfish Clarias gariepinus (Burchell) was examined in fish exposed to different dietary CAD levels (-146, 116, 497, 713 and 828 mEq kg1 diet). The experiment was conducted in open circuit balance respiration chambers over a 3-week period. Five 24-h monitoring periods were carried out at 3-day intervals during the experimental period with O2 consumption, ammonia and nitrate nitrite (NOx) and CO2 production being measured at 5-min intervals for each chamber. The negative dietary CAD (-146 mEq kg1) resulted in the highest energy expenditures (83 kJ kg0.8? d1). With increasing dietary CAD levels, heat loss gradually decreased to minimum values of 56 kJ kg0.8 day1 at a dietary CAD level of 713 mEq kg1. Consequently, metabolizable energy utilization efficiency (MEU, percentage of retained energy over metabolizable energy) quadratically (P < 0.05) increased and reached a maximum at a dietary CAD of 713 mEq kg1.

Johan A.J. Verreth

Papers

The effect of feeding level on growth and survival of jaguar guapote (Cichlasoma managuense) larvae fed Artemia nauplii

Stressing fish in Recirculating Aquaculture Systems (RAS): does stress induced in one group of fish affect the feeding motivation of other fish sharing the same RAS

Experimental validation of geosmin uptake in rainbow trout, Oncorhynchus mykiss (Waldbaum) suggests biotransformation

Environmental requirements and heterogeneity of rheophilic fish nursery habitats in European lowland rivers: Current insights and future challenges

Metabolic costs of changing the cation–anion difference in the diet of juvenile African catfish Clarias gariepinus (Burchell)