Maria Lucia Negreiros-Fransozo

The evaluation of the effects of early starvation and feeding on survival and growth in the early stages of the life cycle of ornamental marine caridean shrimp species is fundamental to establish adequate feeding protocols in their culture. In this study, we determine the nutritional vulnerability in the early larval stages of ornamental shrimp Lysmata ankeri exposed to different periods of starvation or feeding. The larvae were separated into three groups (zoea I-ZI, zoea II with ZI fed, and zoea II with ZI unfed) and subjected to two experiments: (1) point-of-no-return (PNR), comprising one or two days of initial starvation followed by feeding; and (2) point-of-reserve-saturation (PRS), comprising one or two days of initial feeding followed by starvation. Each experiment was still composed of two control groups: continuous feeding and continuous starvation. Larvae tolerated some periods of starvation, with a high PNR value (2.00) and low PRS (0.50). Longer periods of starvation influenced both growth and survival rates in zoea II stages. The nutritional vulnerability index for zoea I was 0.25, which represents a low dependence on food supply. In this study, it was observed that ornamental shrimp L. ankeri larvae hatch with energy reserves, presenting facultative primary lecithotrophy, in which they are able to moult from zoea I to zoea II using such reserves in the absence of food. In this sense, the early larvae stages (zoeas I and II) can tolerate a certain period of starvation, indicating the great potential of this species for aquaculture.

We investigated the relative growth and sexual maturity (gonadal and morphometric) of Libinia spinosa. Crabs were sampled at Ubatuba from January to December 2000, using trawls. Based on allometric growth, males were grouped into juveniles (MJ), adolescents (MAd) and adults (MA) based on the relationship CPL (major cheliped propod length) vs. CW (cephalothorax width), all with positive allometric growth. For females, the relationship AW (abdomen width) vs. CW allowed segregating juveniles (FJ) from adults (FA), with positive allometric growth for FJ but isometric growth for FA. The morphometric maturity evidenced for MAd varies from 33.7 mm to 34.5 mm and for MA and FA. The size in which 50% of individuals reach the morphometric sexual maturity was L₅₀ = 50.1 mm for males and L₅₀ = 37.3 mm for females. Gonad maturity was L₅₀ = 33.7 mm for males and L₅₀ = 36.9 mm for females. Through relative growth analyses, we identified an adolescent male group (prepuberal phase). These individuals presented mature gonads, enabling them to copulate with females. These adolescent males may reproduce while avoiding competition with adult males, as it happens in other species of Majoidea that present more than two morphotypes in the population.

The morphology of juveniles of Mithraculus forceps A. Milne-Edwards, 1875, raised in the laboratory, is described. The larvae were obtained from ovigerous females collected in the wild, maintained in the rearing system for culture of crabs (400 L). A total of 229 larvae (zoea I), from 7 females were distributed in lots of 20 larvae kept in glass flasks (500 ml), with seawater circulation and temperature and salinity constants, which were checked daily for molts or deaths. After the larvae reached the juvenile stage, exuviae and dead specimens were deposited in a scientific collection. We analyzed the external morphology (N = 10 ind.) of each size class (total = 8). We determined the number of size classes, based on carapace width CW vs. carapace length CL (mm) and its dispersion points, in which we can observe non-hierarchical groupings with no size classes overlapping. We analyzed the relative growth of the juveniles using the technique “Standard Major Axis’’ (Type II regression). The relationships CW vs. CL and CW vs. AW showed negative allometry (b < 1; p < 0.05). The relationships CW vs. CPH and CW vs. CPL are isometric (b = 1; p > 0.05). The most remarkable morphological characters of the juveniles (first size class) are the following: spines at the anterior margin of the carapace, inner marginal teeth in the propodus and dactylus of the chelipeds, number of articles in the antennular endopod and the maxillular endopod, absence of setae on the maxillar endopod, and absence of rudimentary pleopods.

The growth rates and size at maturity of decapod crustaceans usually vary throughout latitudes. Here, we evaluated whether these life history traits can be stable within the same latitude range, where some environmental factors are constant, especially temperature. To this end, we estimated and compared the growth rates and size at sexual maturity of three populations of the fiddler crab Minuca vocator, located at latitude 23° S, in mangroves of the subtropical Brazilian coast. Variations in the growth rate of the abdominal width of females and of the propodus of the major cheliped of males were assessed by the allometric technique. The abdomen growth rates of females and the cheliped growth rates of males varied among the three populations, resulting in different sizes at maturity. These results do not support our prediction that growth rates and size at sexual maturity would remain stable in populations of the same latitude range. The differences in these life history traits could be a consequence of contrasting local conditions among mangroves. Therefore, we suggest that these crabs show plasticity and responsiveness to local-scale environmental variations, to optimize the energy allocation for maintenance, reproduction, and somatic growth.

The shrimp Potimirim brasiliana plays an important role in streams along the Brazilian coast as it feeds on the organic debris from the surrounding ecosystem. We determined the morphological sexual maturity of P. brasiliana by means of relative growth. Monthly throughout a year, we used sieves (2 mm mesh diameter) to collect the specimens in a coastal stream. A total of 3,521 specimens had their carapace length (CL) measured, as well as their second pleura length (PL) and the length (AML) and width (AMW) of the appendix masculina. The studied relationships were the following: CL vs. PL; CL vs. AML and CL vs. AMW, with the data adjusted to a logistic equation. All the relationships tested among the demographic groups differed statistically. The CL50 of females measured 3.45 mm, while the CL50 of males measured 2.75 mm. Two adult morphological groups were set apart for each sex. The CL vs. AMW relationship is the best at demonstrating the separation of the morphological groups for males. This fact is an intriguint issue as it suggests the presence of morphotypes in males, probably, playing different roles in the reproductive process.

Since 1985, 17 established populations of P. clarkii have been recorded in Brazil, all located in the southeast region of São Paulo State (^{Magalhães et al., 2005}; ^{Loureiro et al., 2015}). The specimens were introduced either accidentally or deliberately via the aquarium trade (^{Loureiro et al., 2015}). The aim of this study is to present the first record of this species in Paraná State, southern Brazil, expanding its range of invasion in the country.

Our aim was to describe the reproductive system of males and the formation of sperm packages in the seminal receptacle (SR) of recently mated females of the arrow crab Stenorhynchus seticornis. The male reproductive system was analyzed, and was described using light microscopy and histological and histochemical methods. The first pair of gonopods was described by means of scanning electron microscopy. Additionally, the dehiscence of spermatophores was tested using samples obtained from the vas deferens of males and from the seminal receptacle of recently mated females. Testes were tubular type, and each vas deferens consisted of three regions: the anterior vas deferens (AVD), including a proximal portion that was filled with free spermatozoa and a distal portion contained developing spermatophores; the median vas deferens (MVD) that contained completely formed spermatophores; and the posterior vas deferens (PVD), which contained only granular secretions. The accessory gland, which was filled with secretions, was located in the transition region between the MVD and the PVD. The spermatophores from the MVD were of different sizes, and none of them showed dehiscence in seawater, whereas those spermatophores in contact with the seminal receptacle were immediately broken. The ultrastructure of the gonopods revealed the presence of denticles at the distal portion, which contribute to the mechanical rupture of the spermatophore wall during the transfer of sperm. The contents of the PVD and accessory gland of males are transferred together with the spermatophores, and are responsible for the secretions observed among the sperm packets in the SR of the female. We suggest that these secretions formed the layers found in the SR of recently mated females, and may play a role in sperm competition in arrow crabs.

Knowledge of the critical points in larval stages is essential to evaluate the physiological state of the larvae in their natural environment. This study investigated the nutritional vulnerability index (NVI) of the first (ZI) and second (ZII) zoeal stages of Stenorhynchus seticornis. Zoeae were assigned to two experiments: (1) point of no return (PNR), consisting of treatments with increasing days of starvation and subsequent days of feeding; and (2) point of reserve saturation (PRS), consisting of treatments with increasing days of feeding and subsequent days of starvation. There were two control groups: continuous starvation (CS) and continuous feeding (CF). Mortality was used to estimate the time when 50% of initially starved larvae (PNR50) lost the ability to moult to the next stage and when 50% of initially fed larvae (PRS50) were capable of moulting to the next stage. The mean (±s.d.) development time of ZI and ZII under CF was 4.4 ± 1.2 and 5.1 ± 1.8 days respectively. Mortality in the CF groups was 30 and 52% for ZI and ZII respectively. For ZI, PNR50 and PRS50 were 1.0 ± 0.0 and 2.1 ± 1.0 days respectively. The estimated NVI for ZI was 2.2, which indicates that S. seticornis depends on exogenous food and is considered planktotrophic during the first larval stage.