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.

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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.

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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.

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The Ecology of Phytoplankton

The repeatability of behaviour: a meta-analysis.

Using capture fishery-derived fish oil and fishmeal in aquafeeds is unsustainable. This study mimicked semi-intensive shrimp ponds, including primary producers, in mesocosm tanks. Fatty acid mass balances were computed to distinguish between diet-based and primary production-based LC-PUFA contributions to shrimp (Litopenaeus vannamei) production and meat quality. Performance and body fatty acid composition were compared of shrimp fed a commercial diet containing fish oil and fishmeal (control), with a fishmeal- and fish oil-free diet (low LC-PUFA diet: LOW). Six mesocosms were each stocked with 60 juvenile shrimp and randomly assigned to the two diets. After an 8-week grow-out period, biomass production, survival and proximate body composition were similar between diets. Control shrimp contained twice as much LC-PUFA and omega-3 fatty acids than LOW shrimp. Large quantitative losses (85%) were found in both treatments of the LC-PUFA-precursors alpha-linolenic acid (ALA) and linoleic acid (LA) that were being used as energy source by the shrimp instead for LC-PUFA synthesis. Whereas losses were also observed for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the control group, there was a gain for these components in the LOW tanks. LOW shrimp sourced at least 32% of their total EPA gain and 15% of their total DHA gain from the algal-based food web. This quantitative analysis of the fate of major dietary fatty acids strongly suggests that the pond's primary production can provide shrimp additional LC-PUFA. Finding a balance between LC-PUFA contribution through formulated feed and natural production seems possible and deserves further research.

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In situ fatty acid production supports shrimp yields in diets lacking fish oil and fishmeal

Common sole (Solea solea L.) is a polychaetemollusc feeder (de Groot 1971). Based on the feeding ecology of sole, we assume that both ragworm (Nereis virens, Sars) and mussel (Mytilus edulis L.) reflect the dietary requirements of common sole. Common sole grows approximately 70% faster on ragworm than on commercial pellets (Ende, Kroeckel, Schrama, Schneider & Verreth 2014), the latter causing them to suffer from nutritional anaemia (Kals, Blonk, Palstra, Sobotta, Mongile, Schneider, Planas, Schrama & Verreth submitted). Changing the diet from pellet to ragworm alleviates this nutritional anaemia (Kals, Blonk, van der Mheen, Schrama & Verreth 2015). This suggests a mismatch between the feeding requirements of sole and the dietary composition of the commercial pellets. Fonds, Drinkwaard, Resink, Eysink and Toet (1989) and Ende et al. (2014) showed that the growth of sole fed mussel is comparable to the growth of sole fed ragworm. We, therefore, expect that also mussel will alleviate anaemia in sole, consequently showing comparable levels of haematocrit (Hct) and haemoglobin (Hb) for sole fed mussel or ragworm, but higher for sole fed pellet. Apart from trying to find evidence for the foregoing hypothesis, we wanted to gain insight into which dietary components could be important to alleviate nutritional anaemia in sole. This experiment was approved by the Ethical Committee for Animal Experiments and conducted at IMARES, Yerseke, the Netherlands. The experimental set-up contained three diets; raw mussel meat (mussel), fresh ragworm (ragworm) and a commercial pellet (pellet) (crude protein 63%, ether extract 14%, ash 12%). The diets were tested in triplicate for a period of 23 days with 10 fish per tank, or 90 fish in total. Mussels were collected at the Oosterschelde, the Netherlands. The meat was separated from their shell and stored at 80°C. The frozen mussel was thawed in a fridge the day before feeding. Ragworms were delivered by Topsy Baits, Wilhelminadorp, the Netherlands. Sole (220 44 g) reared on pellet and na€ıve to ragworm and mussel were randomly accommodated in 9 tanks (0.4 m, 130 L), in a flow through system using sand filtered seawater. Husbandry conditions were as follows: photoperiod 12L:12D, light intensity 11–15 lux, temperature 16.9 1.3°C, oxygen 8.3 0.5 mg L , pH 8.1 0.1, TAN 0.3 0.2 mg L , NO2 , 0.01 0 mg L , salinity 25– 30 g L 1 and flow 4.5 0.5 L min 1 kept within pre-set limits. Temperature and oxygen were measured daily; flow, pH, TAN, NO2 weekly. Fish were fed by hand twice a day (8:30 and 16:30 hours). During acclimatization, all fish were fed the pellet. The dry matter content of the diets was analysed to enable equal feeding levels (restricted to 0.54 g dm per fish per day) for all diets. One hour after feeding,

Mussel (Mytilus edulis L.) and ragworm (Nereis virens, Sars) both alleviate anaemia in common sole (Solea solea L.)

Polychaetes comprise the benthic meiofauna of the soft-bottom intertidal zone and of shrimp ponds in coastal areas. While polychaetes provide benefits to the shrimp farming industry as (i) natural food in traditional shrimp ponds, (ii) nutrient regenerators through bioturbation and removal of organic waste in the sediment through feeding, and (iii) feed supplement to enhance maturation of shrimp brooders, the conditions present in aquaculture ponds may increase the opportunity for polychaetes to transfer pathogens to shrimp through the food chainThere is growing concern that internationally traded polychaetes, which are fed to shrimp brooders, are potential vectors for the transmission of other shrimp pathogens. The detection of the aetiological agents of two newly emerging diseases of shrimp in polychaetes, Enterocytozoon hepatopenaei (EHP) and Vibrio parahaemolyticusAHPND causing hepatopancreatic microsporidiosis (HPM) and acute hepatopancreatic necrosis disease (AHPND), respectively, suggests that these worms can be a host or/and passive carrier of these pathogens. This review discusses the benefits of polychaetes to shrimp farming, the risk of shrimp pathogen transmission by polychaetes at the pond, hatchery and global level, and calls for closer observation on shrimp pathogens in polychaetes used as shrimp feed.

Polychaetes as potential risks for shrimp Pathogen transmission

A matter of perception: The influence of waterborne signals from fish and conspecifics on the feeding related behavior of Alitta virens (Sars)

This study compares the effect of food type (formulated diet vs. natural food) and fish size on protein and energy utilization efficiencies for growth in common sole, Solea solea (L.). Replicate groups of common sole (mean initial body weight ± SD was 45.7 g ± 2.1 and 111.2 g ± 4.2) received the diets at five (natural feed) or four (formulated diet) feeding levels. The protein utilization efficiency for growth (kgCP) was higher (P > 0.001) in common sole fed ragworms than in common sole fed the formulated diet (respectively, 0.40 and 0.31). Likewise, the energy utilization efficiency for growth (kgGE) was higher (P = 0.001) in common sole fed ragworms than in common sole fed the formulated diet (respectively, 0.57 and 0.33). The protein maintenance requirement was not different between food types (P = 0.64) or fish size (P = 0.41) being on average 0.82 g kg−0.8 day−1. The energy maintenance requirement was not different between food type (P = 0.390) but differed between fish size (P = 0.036). The gross energy maintenance requirement of small common sole was 35 kJ g−0.8 day−1. The gross energy maintenance requirement of large common sole was 25 kJ g−0.8 day−1. In conclusion, the low growth of common sole fed formulated diets was related to reduced feed utilization.

Johan A.J. Verreth

Papers

In situ fatty acid production supports shrimp yields in diets lacking fish oil and fishmeal

Mussel (Mytilus edulis L.) and ragworm (Nereis virens, Sars) both alleviate anaemia in common sole (Solea solea L.)

Polychaetes as potential risks for shrimp Pathogen transmission

A matter of perception: The influence of waterborne signals from fish and conspecifics on the feeding related behavior of Alitta virens (Sars)

The effect of food type (formulated diet vs. natural) and fish size on feed utilization in common sole, Solea solea (L.)