Compostos nitrogenados sobre o consumo alimentar de camarão-rosa Farfantepenaeus brasiliensis / Nitrogen compounds on food consumption of pink-shrimp Farfantepenaeus brasiliensis

Os experimentos foram realizados para investigar os efeitos da amônia, nitrito e nitrato no consumo alimentar de juvenis de Farfantepenaeus brasiliensis. Os camarões com peso médio de 4g foram aclimatados durante 28 dias em diferentes concentrações crônicas de amônia, nitrito e nitrato. Após o período de exposição de 28 dias, 20 camarões por tratamento foram individualizados em unidades experimentais de 3 L, a fim de ser analisado o consumo de ração em função da quantidade de alimento oferecido e as sobras durante um período de 24 horas. O consumo alimentar apresentou alterações significativas (P<0,05) para os camarões expostos às concentrações de nitrito e nitrato testadas, enquanto para o tratamento com amônia, os camarões não apresentaram alterações no consumo alimentar (P>0,05). Foi verificado que o nitrito e o nitrato afetam o consumo alimentar de F. brasiliensis. Contudo, a possibilidade de que isso ocorra durante longos períodos, afetando negativamente o cultivo de espécies em cativeiro, reforçam a necessidade do manejo da qualidade de água.

The experiments were carried out to investigate the effects of ammonia, nitrite and nitrate on food consumption of juvenile F. brasiliensis. The juvenile shrimp were acclimated for 28 days with different cronic concentrations of ammonia, nitrite and nitrate. After the acclimation period, 20 shrimps per treatment were individualized in 3 L experimental units in order to analyze their feed intake through the amount of feed offered and leftover for a period of 24 hours. The food consumption presented significant alteration (P<0.05) for the nitrite and nitrate concentrations tested, meanwhile on ammonia treatment, shrimp presented no alteration on food intake (P>0.05). According to the results obtained, nitrite and nitrate affected F. brasiliensis food consumption. However, the possibility of this to happen over long periods, can damage the species in captivity, reinforced the necessity of regular water quality management.

Shrimp farming as an alternative to artisanal fishermen communities: the Case of Patos Lagoon, Brazil

The shrimp Farfantepenaeus paulensis is considered a suitable species for culture in the Patos Lagoon estuary, southern Brazil, where its catch has been decreasing in the last few years. Considering the potential of estuarine areas for shrimp farming, the application of low-cost structures to culture shrimp, such as the pen enclosures, is being proposed as an alternative source of income for artisanal fishermen and farmers living near Patos Lagoon. From an economical standpoint, these alternative systems present several advantages over the traditional pond-based culture systems since land, water pumping and artificial aerations are not required, high natural productivity is available and inexpensive materials are employed in the construction of grow-out structures. This paper reviews the farming of F. paulensis in the pen enclosures as an alternative to the artisanal fishing communities of the Patos Lagoon estuary. Particular emphases are placed on the development of culture systems, social and environmental impacts, constraints and perspectives.

O camarão-rosa Farfantepenaeus paulensis é considerado uma espécie com potencial para criação no estuário da Lagoa dos Patos, RS, onde o volume desembarcado deste recurso vem decrescendo nos últimos anos. A criação deste camarão em cercados está sendo proposta como uma fonte de renda alternativa para os pescadores artesanais e agricultores que habitam o entorno deste estuário. Do ponto de vista econômico, estes sistemas alternativos de criação apresentam vantagens sobre os sistemas tradicionais em viveiros de terra: não se necessita ter posse da terra, nem equipamentos de bombeamento d'água ou aeração. Além disso, materiais relativamente baratos são utilizados na construção das estruturas de engorda e há uma grande disponibilidade de alimento natural. Esta revisão apresenta alguns aspectos da criação de F. paulensis em cercados como uma alternativa às comunidades de pescadores. Maior ênfase será dada no desenvolvimento dos sistemas de criação, manejo, impactos sociais e ambientais, dificuldades e possibilidades.

The effect of temperature, salinity and nitrogen products on food consumption of pink shrimp Farfantepenaeus paulensis

Studies were carried out to investigate the effect of temperature, salinity, ammonia, nitrite and nitrate on food consumption of pink shrimp Farfantepenaeus paulensis. Juveniles (0.2 - 0.4 g) were acclimated for 15 days in seawater with different temperatures, salinities and concentrations of ammonia, nitrite and nitrate. After the acclimation period, 20 shrimps per treatment were individualized in order to have their ration intake analyzed through the amount of ration offered and left over within a 24-hour period. Mean food consumption presented significant alterations (P<0.05) for the tested temperatures and nitrite concentrations, whereas for the salinity, ammonia and nitrate treatments, shrimp presented no alteration on food intake (P>0.05). According to the results obtained, temperature and nitrite affected F. paulensis food consumption. On the other hand, variables as salinity, ammonia and nitrate did not affect shrimp appetite. However, the possibility of this to happen over long periods, prejudicing the species culture in captivity, reinforced the necessity of regular water quality management

Toxicidade aguda da amônia no processo produtivo de pós-larvas de Penaeus paulensis Pérez-Farfante, 1967 / Acute toxicity of ammonia in the productivity process of postlarvae of Penaeus paulensis Pérez-Farfante, 1967

Larval shrimp Penaeus paulensis showed a tendency to decrease in ammonia tolerance as the larva metamorphosed from nauplius to postlarvae stage. The 24-h LC50 were 4.04, 1.70, 2.72, and 1.42mg/l NH3-N on nauplii, zoea, mysis and postlarvae, respectively. The zoea stage and the initial postlarvae substages were very susceptible to ammonia. The 96-h LC50 values on zoea and postlarvae were 0.69 mg/l and 0.32 mg/l, against 0.80 mg/l NH3-N on mysis. The eggs of Penaeus paulensis were affected by ammnia, which provoked a progressive decrease in the hatching rate and induced morphological deformities in hatched nauplii. A "safe level" of ammonia was estimated at 0.032 mg/l NH3-N on the basis of 24-h LC50 for eggs