Ablação ocular no camarão Macrobrachium rosenbergii (De Man) (Crustacea, Decapoda, Palaemonidae): efeitos sobre a reprodução, pigmentação epidérmica e atividade alimentar

Abstract

ABSTRACT. Eyestalk ablation in lhe prawn Macrobrachillm rosellbergii (De Man) (Cruslacea, Decapoda, Palaemonidae): effecls on reproduction, epidermic pigmenlation and feeding aclivity. This study analyze the consequences ofunilateral and bilateral ablation based on ovigerous percentage, consecutive spawns, and secondary effects ofthe surgical process in the lemales of Macl'obl'achium I'osenbel'gii (De Man , 1879). Two experiments were carried out with four and seven months old females in intelmolt stage. Each experiment was comprised ofconlrol, unilateral and bilateral ablation. Eyestalk ablation was done with a bistouly with a topic hot cauterization followed by application of antibiotic pomades. The animais were maintained at constant temperature (28 ± 1,05°C) and photoperiod of 12L:12D within fibercement boxes with sandy bottom and biological filter. Females were observed once a day during foulteen weeks, registering gonadal condition, ecdysis and presence of spermatophore (mating) and spawning. Unilateral ablation technique is more etlicient due to the anticipation ofthe first spawn, repeatability between spawns, expressive rate oI' ovigerous females and survival , that favored its applicability. Bilateral eyestalk ab lation produced the mortality 01' ali the females with change in coloration and food ac tivity patterns. These results corroborate other observations on penaeid shrimps, though bi lateral ablation on some lobsters was a success. These results showing an interespecitic variation and can be used in aquaculture projects. KEY WORDS . ClUstacea, eyestalk ablation, reproduction, pigmentation, feeding activity, prawn A obtenção de pós-larvas do camarão de água doce Macrobrachium rosenbergii (De Man, 1879) é limitada pela baixa disponibilidade de fêmeas ovígeras durante os meses de inverno em regiões de clima subtropical. Quando a temperatura da água dos viveiros é inferior a 18°C, os camarões apresentam uma diminuição do crescimento somático e da atividade reprodutiva, resultando, muitas vezes, em alta mortalidade. Após a água dos viveiros ganhar calor gradativamente, o cultivo pode ser reiniciado, embora, nesta ocasião, os criadores não possuam um número suficiente de pós-larvas para o povoamento; tal fato se deve à temperatura e fotoperíodo reduzidos, responsáveis pela minimização do processo reprodutivo na maioria dos crustáceos decápodosjá estudados (STEELE et aI.

Unilateral eyestalk ablation improves molting frequency and reproduction in Macrobrachium amazonicum females

“…Gonad-inhibiting and molt-inhibiting hormones are associated with the eyestalk. Therefore, eyestalk removal can be used to stimulate the first spawning, increase the number of molts and consecutive spawns, decrease the intermolt and interspawn periods, and increase the gonadosomatic indexes and size of the androgenic gland (Okumura and Aida 2001;Santos and Pinheiro 2000;Uawisetwathana et al 2011;Varalakshmi and Reddy 2010). In this current study, unilateral eyestalk ablation led to a 30% increase in the number of ovigerous females and a 13% increase in the number of molts.…”

“…Increased body weight and body length of ablated females may be explained by a decrease in the feed-inhibitory factor, leading to changes in dietary patterns and accumulation of reserves. These changes frequently occur in crustaceans subjected to ablation-for example, Penaeus orientalis (Arnstein and Beard 1975), P. monodon (Santiago 1977;Shailender et al 2013), M. rosenbergii (Santos and Pinheiro 2000;Shailender et al 2013), M. malcolmsonii (Soundarapandian 2008), M. lanchesteri (Varalakshmi and Reddy 2010), and M. acanthurus (Cunha and Oshiro 2010). Thus, ablation may accelerate the metabolic rate and increase food consumption.…”

“…In general, the length of the crustacean molting cycle increases as growth occurs (Asusena et al 2012;Lobão, Rojas, and Valenti 1986;Santos and Pinheiro 2000). Reproduction (consisting of copulation and spawning) in Macrobrachium species and other caridean prawns is preceded by molting.…”

“…The influence of the ablation on survival may be immediate or long-term (Lumare 1979;Pervaiz, Jhon, and Sikdar-Bar 2011;Primavera 1985;Varalakshmi and Reddy 2010;Wen et al 2015). In some cases, mortality occurs immediately after ablation owing to the loss of hemolymph or presence of infection (Santos and Pinheiro 2000). In some species such as P. monodon (Vicente, Valdez, and Valdez 1979), P. plebejus (Kelemec and Smith 1980), and M. americanum (Asusena et al 2012), ablation does not influence survival.…”

“…The eyestalk ablation has been used to induce gonadal maturation, stimulate the ovigerous state, increase the spawning frequency, and reduce the intermolt period in Macrobrachium species (Asusena et al 2012;Cunha and Oshiro 2010;Pervaiz, Jhon, and Sikdar-Bar 2011;Santos and Pinheiro 2000). To the best of our knowledge, however, there are no previous studies regarding the use of eyestalk ablation in M. amazonicum.…”