Dendrorremediación: El uso de Betula alba para monitorizar y reducir el contenido de metales en suelos mineros.

[EN] The intense industrial activity that took place over the past century resulted in large contaminated áreas. This is an important risk to human health and environmental safety. Recent biotechnological techniques for bioremediation include phytoremediation, which uses plants to remove or stabilize contaminants in soils. In our study we choose birch (Betula alba) as the preferred species to remedy mining soils, due to it produces a large biomass and can accumulate high levels of toxic elements in its tissues. The aim of this study was (i) to determine the possibility of using this species in reforestation and/or remediation of mining soils (ii) to elucidate the potential of tocopherol levels as indicators of heavy metal pollution. Trees growing in mining soils with high concentrations of Zn, Cd and Pb were sampled and the metal content in various organs and in tree rings was analyzed. α-tocoferol levels were also analyzed as an indicator of stress. The results showed a different distribution of metals in plant tissues. Zn and Cd had a higher accumulation in leaves, whereas Pb was stored in the timber. In addition, the metal content in tree rings was higher in older rings, leading to a conclusion that older tissues present a detoxification strategy. Furthermore, we saw how the presence of α- tocoferol on branches can be an indicator of metal stress in plants and it can be also used as a monitoring factor.

Potential of genetics for aquaculture development in Africa

Aquaculture in Africa is fairly insignificant by world standards and accounts for a mere 0.4 per cent of global aquaculture production. The application of genetics can play an important role in efforts to increase aquaculture production in Africa through methods such as selective breeding, hybridization, chromosome manipulation and use of YY “supermales”. Other issues that need to be addressed are limited genetic research facilities, funding, human capacity and suitable species for aquaculture.

The fisheries of Zanzibar: potential for new investments

Zanzibar, one of the poorest areas of sub-Saharan Africa, has a good potential for foreign investment in offshore (EEZ) marine capture fisheries, in aquaculture and in fi sheries infrastructure. Zanzibar’s fisheries resources could be better managed in an effort to alleviate the poverty of its rural population and to provide food security. At present, Zanzibar’s fisheries are artisanal and its total annual production of fish of just over 20000 t, caught in inshore waters, is consumed locally. The government of Zanzibar has liberalized its policies to make Zanzibar a good environment for foreign investment.

Potential of grouper hybrid (Epinephelus fuscoguttatus x E. polyphekadion) for aquaculture

The marine grouper species are considered high value food fish in several countries. However, controlled breeding and hatchery production of grouper fingerlings for commercial farming is still in its infancy. Investigations on the growth performance of the brown marbled grouper Epinephelus fuscoguttatus (Forskal), camouflage grouper E. polyphekadion (Bleeker) and their hybrid (E. fuscoguttatus x E. polyphekadion) under hatchery and growout culture conditions indicate the potential of grouper hybrids for aquaculture.

Potential for the development of aquaculture in Africa

Aquaculture production in Africa has remained low despite the huge potential that exists on the continent. In order for this potential to be realized, it is necessary to refocus the direction of aquaculture development. This paper concludes that for further growth to occur it is necessary to: (i) widen the range of production systems; (ii) increase production intensities and efficiencies; (iii) develop management technologies for indigenous species that target local niche markets; (iv) put more emphasis on marketing and processing of high value products; (v) promote policy research on how aquaculture production can respond to changing macroeconomic policies; and (vi) accelerate the disengagement of government from activities that can best be done by the private sector.

The potential for crop rotation in controlling diseases in shrimp culture

The use of antibiotics and other chemicals in controlling shrimp pathogens become ineffective as the strains grow more resistant to these chemicals. Moreover, the bacterial pathogen (Vibrio harveyi) produced biofilm coating that protects it from dying and disinfection procedures that are followed during pond preparation. Biological control is being considered as an alternative means of preventing shrimp disease outbreak. The main principle behind biological control is to enhance the growth of beneficial microorganisms which serve as antagonists or target pathogens. The paper discusses shrimp and tilapia crop rotation as a form of effective biological control, a technique which is already being practiced in Indonesia and the Philippines.

Aquaculture potential of seahorses and pipefishes

The characteristics, food and feeding, reproduction and breeding of sea horse and pipefishes (Synanthidae) are presented together with the aspects of syngnathid culture.