Effects of photoperiod on reproduction of Siamese fighting fish Betta splendens

This study investigated the effect of different photoperiods (24 h of light (L):0 h of darkness (D); 20L:4D; 16L:8D; 12L:12D; and 8L:16D) on the reproduction and growth of Betta splendens. The results showed that spawning frequency was significantly higher in couples reared under 16L:8D and 12L:12D, in comparison with other treatments. The highest number of eggs per spawn was obtained under 16L:8D (544.76±375.23) and 12L:12D (471.13±261.52), and the lowest values were detected for 24L:0D (128.55±58.14) and 20L:4D (187.87±103.84). Fertility and fecundity also showed significantly higher average values in 16L:8D and 12L:12D when compared with 24L:0D and 20L:4D treatments. Egg volume and perivitelline space were significantly higher in 24L:0D treatments that showed the lowest numbers of eggs per spawn, while the vitelline volume did not show significant differences. Other variables such as breeders weight gain and condition factor (K) were not statistically different. Moreover, the final length varies according to photoperiod and gender. These results demonstrated a key role for the photoperiod upon B. splendens reproduction. The best reproductive performance is achieved under the photoperiods that best approached those that occur in spring and summer (16L:8D and 12L:12D), coinciding with their best seasons for reproduction.

Germinação e armazenamento de sementes de COCA (Erythroxylum ligustrinum DC. - Erythroxylaceae)

O objetivo deste trabalho foi avaliar o efeito da temperatura sobre a germinação e o armazenamento de sementes de Erythroxylum ligustrinum DC. As sementes foram colocadas germinar caixas de plásticas sobre duas folhas de papel, umedecidas com Nistatina 0, 2%, mantidas em germinadores nas temperaturas constantes de 5, 10, 15, 20, 25, 30, 35, 40 e 45ºC e com fotoperíodo de 12 horas. Para o armazenamento, as sementes foram colocadas em sacos de papel, mantidos à temperatura ambiente e em geladeira. em seguida, mensalmente, foi avaliada a germinação das sementes. A temperatura mínima, a faixa de temperatura ideal e a temperatura máxima para germinação de sementes de coca estão entre 10 e 15ºC, 25 e 30ºC e 40 e 45ºC, respectivamente. O armazenamento de sementes coca por longo período é inviável em embalagens de papel na geladeira (10ºC ± 2) e em temperatura ambiente (27ºC ± 5).

Growth of the mangrove crab Ucides cordatus (Brachyura, Ocypodidae)

During monthly samplings between September 1998 and August 2000. 3,660 specimens of Ucides cordatus (Linnaeus, 1763) (2054 males and 1606 females) were obtained and examined for size (CW carapace width) to determine growth-age equations for each sex. This species showed a slower growth, with a marked seasonal oscillation, in females as compared to males, suggesting application of the seasonal and nonseasonal von Bertalanffy growth model, respectively. CW∝ and k constant were closely similar for the two sexes (CW∝ (male) = 90.3 mm: CW∝ (female) = 88.6 mm; k(male) = 0.28; k(female) = 0.26). The age at sexual maturity was estimated to be around 3 years, while the age at legal size (CW = 60 mm) was 3.8 and 4.7 years for males and females, respectively. In the laboratory, juvenile stages did not show differences in growth rates under the same temperature and photoperiod conditions.

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

This study analyze the consequences of unilateral and bilateral ablation based on ovigerous percentage, consecutive spawns, and secondary effects of the surgical process in the females of Macrobrachium rosenbergii (De Man, 1879). Two experiments were carried out with four and seven months old females in intermolt stage. Each experiment was comprised of control, unilateral and bilateral ablation. Eyestalk ablation was done with a bistoury with a topic hot cauterization followed by application of antibiotic pomades. The animals were maintained at constant temperature (28 ± 1,05ºC) and photoperiod of 12L: 12D within fibercement boxes with sandy bottom and biological filter. Females were observed once a day during fourteen weeks, registering gonadal condition, ecdysis and presence of spermatophore (mating) and spawning. Unilateral ablation technique is more efficient due to the anticipation of the first spawn, repeatability between spawns, expressive rate of ovigerous females and survival, that favored its applicability. Bilateral eyestalk ablation produced the mortality of ali the females with change in coloration and food activity patterns. These results corroborate other observations on penaeid shrimps. though bilateral ablation on some lobsters was a success. These results showing an interespecific variation and can be used in aquaculture projects.

Tecido hepático e corpo adiposo de rã-touro (Lithobates catesbeianus) submetido a diferentes fotoperíodos

The study was conducted to evaluate the liver tissue weight, body fat weight, the fatty somatic index and the liver somatic index of bullfrogs subjected to three photoperiod during the growing phase (initial 30 days) and finishing (60 days). The treatments were 16 h light and 8 h dark, 12 h of light and dark and 8 h light and 16 h dark. The experimental design was completely randomized design with three replications. We used 36 bullfrogs/m2 weighing from 22 to 28 g. The results were submitted to ANOVA and Tukey Test at 5% probability. Differences were found for the weight of body fat, liver tissue weight, liver somatic index and fatty somatic index the bullfrog to the treatments and the study periods and there is greater accumulation of energy to ninety days. The photoperiod did not influence body weight and fat weight of the liver tissue of bullfrog at the end of the fattening period and the difference fatty somatic index and liver somatic index were influenced by body weight of animals.