Percentage Of Ovigerous Females Research Articles

Long-Term Exposure of the Red Cherry Shrimp Neocaridina davidi to Diclofenac: Impact on Survival, Growth, and Reproductive Potential.

The current study was aimed at studying the long-term effects of diclofenac on the freshwater shrimp Neocaridina davidi, concerning survival, somatic growth, and reproduction. In this study, both ovigerous females and males of this species were exposed for 63 d to 0 (control), 0.1, or 1mg/L of diclofenac. At the highest concentration, significant mortality was detected, and the somatic growth of females was significantly decreased. The percentage of females with a second spawn, observable from day 45, significantly increased at 1mg/L, while the time between spawns was significantly reduced at both concentrations assayed. However, the gonadal analysis made at the end of the assay in the surviving females showed a significantly lower proportion of advanced oocytes in females exposed to 1mg/L, as compared to control. Concerning hatching, the percentage of ovigerous females that could have successful hatching was reduced at 1mg/L of diclofenac, especially for the first spawn. For the second spawn, the low number of juveniles hatched from females exposed to 1mg/L also showed a significantly higher incidence of morphological abnormalities, such as hydropsy and underdeveloped appendages. Taken together, these results showed that even when diclofenac was able to produce earlier spawns, the reproductive output of each spawn was reduced.

Reproductive traits of the freshwater prawn Macrobrachium amazonicum (Decapoda: Palaemonidae) in an isolated water reservoir

The aim of this study was to analyze the reproductive period, fecundity, egg size and reproductive output (RO) of a hololimnetic population of Macrobrachium amazonicum. The prawns were collected monthly, from May 2017 to April 2018, in a water reservoir isolated from river connections, in Severinia (20o49’31.92” S, 48o49’39.55” W), Sao Paulo, Brazil. Ovigerous females were preserved individually in 70% ethanol. The reproductive period was calculated based on the monthly percentage of ovigerous females. The egg mass was weighed and partially measured. The eggs were counted and classified according to the embryonic developmental stage. The reproductive output was calculated individually by dividing the dry weight of females without eggs by the mass of eggs. The reproductive period was continuous, with peaks in the dry season. Egg volume differed among stages and seasons (ANCOVA, p < 0.05), being larger in the rainy season. The reproductive output differed between seasons (rainy: 12.5 ± 4.8%; dry: 13.9 ± 5.4%, p < 0.05), as well as fecundity (rainy: 585 ± 304 eggs; dry: 613 ± 306 eggs, p < 0.05). We concluded that the reproductive traits of this population differ from those of other populations of M. amazonicum previously studied, and that these differences may be consequences of the isolation of this population.

Interpopulation differences of the burrowing shrimp Callichirus major on urban beaches under different levels of fishing pressure

There is growing concern about the sustainability of burrowing-shrimp fisheries in many coastal areas because of their widespread use as bait and their importance as ecosystem engineers. The response of the target populations to the effect of long-term fishing pressure is still poorly understood. The present study reassessed the growth parameters, size structure and reproductive aspects of an exploited population of Callichirus major in northeastern Brazil, comparing it to a population on a beach where fishing pressure is negligible. The results are also discussed in the light of a previous study at the same site in 1999–2000. Sampling was carried out from September 2015 to May 2017 on two urban sandy beaches. Monthly length (dorsal oval) frequency data were analyzed using the FISAT II software package. Growth parameters were estimated with the ELEFAN I routine, using the von Bertalanffy seasonal growth model. The relationship between fecundity and individual size was estimated by linear regression. The exploited population had individual maximum sizes smaller than both those on the unexploited beach and in the population studied 16 years ago on the same beach. The percentages of ovigerous females were smaller than in 1999, and also differed widely between the two populations, with the exploited-beach population having one-fourth as many ovigerous females. This population showed smaller sizes at sexual maturation and low fecundity, and the females were 20% smaller. This study showed that the observed interpopulational differences in the size structure and reproductive parameters of Callichirus major can be attributed to overfishing, and indicated that the exploited population will tend toward collapse if regulatory measures to limit or prohibit fishing are not implemented.

Effect of food restriction on female reproductive performance in the redclaw crayfishCherax quadricarinatus(Parastacidae, Decapoda)

Aquaculture activity has grown remarkably in the last years, crustaceans being the most profitable products because of their high prices. Feeding costs represent a large portion of total operating costs in the aquaculture industry. In this context, the objective of the present study was to evaluate the effect of food restriction on the reproductive performance of redclaw crayfish Cherax quadricarinatus. Females at the onset of sexual maturity were stocked with males and were fed daily a formulated diet at 1.5% (control group) and 0.5% (restricted group) of their mean weight. The experimental period lasted 105 days. The percentage of ovigerous females and broods successfully hatched tended to be higher in restricted females compared with control females, but egg volume and weight did not differ between both experimental groups. However, the lipid concentration of rematuring ovaries was lower in restricted females than control females, suggesting that food restriction affects the amount of reserves transferred to the ovaries during vitellogenesis. The nutritional state of females was independent of the amount of food provided, as reflected by similar growth parameters and biochemical composition of the hepatopancreas in control and restricted females. Based on these results, we conclude that it is possible to reduce the feeding rate of C. quadricarinatus females to one-third of its original value without affecting their reproductive performance and somatic growth, at least for a 105-day period. This finding provides a useful tool for commercial producers to decrease production costs and improve water quality in culture systems.

An investigation on some biological and reproduction characteristics ofEriphia verrucosa (Forskål, 1775) in the South Black Sea (Turkey)

In this study, a total of 1360 specimens of Eriphia verrucosa were collected from the South Black Sea region of Turkey between February 2012 and January 2013 to determine their biological and reproductive characteristics. The overall sex ratio of all individuals was calculated as 1:0.42 (M/F). The mean carapace width was determined as 6.76, 5.57, and 5.62 cm for males, nonovigerous, and ovigerous females, respectively. The minimum and maximum weight was recorded as 4.07 and 301.4 g for both sexes. The highest correlation between morphological characteristics was determined for carapace length and crab weight in nonovigerous females (R2 = 0.973; N = 317). The percentage of ovigerous females was 6.25% and they were observed only between May 2012 and August 2012. The mean fecundity was calculated as 89,129 ± 8005 eggs. The egg diameter ranged from 499.0 to 701.7 µm with a mean value of 546.36 ± 18.62 µm for stage I, 606.92 ± 15.92 µm for stage II, and 570.96 ± 9.22 µm for stage III.

The Influence of Environmental Factors on the Population Structure and Reproductive Biology of &amp;lt;i&amp;gt;Idotea balthica basteri&amp;lt;/i&amp;gt; (Isopoda, Valvifera) of the Bizerte Lagoon (Northern Tunisia)

The reproductive biology of a natural population of Idotea balthica basteri (Pallas, 1772) collected from Menzel Jemil (Bizerte lagoon, Tunisia) was monthly studied from October 2009 to October 2010. Besides water temperature, salinity, turbidity, pH, and dissolved oxygen were measured. Based on the state of differentiation of individuals, the population was divided into 8 categories. Their numbers depend on the one hand to intrinsic factors imposed by the specimens and the structure of the population themselves, and to extrinsic factors due to the variability of environmental conditions on the other hand. Females were morphologically recognisable at smaller size than males. Reproductive activity, which was reflected through the presence of ovigerous females and juveniles, underwent fluctuations throughout the year, but it was continuous. Moreover, salinity, temperature, nitrates, and plant biomass have a noticeable effect on the fecundity and fertility. The Principal Component Analysis also confirmed that the richness of the water in nitrates would be favorable to fecundity and fertility of Idotea balthica basteri. However, higher phosphate concentrations, in April and May seem to have a positive effect on the sex ratio. Otherwise, the temperature would be responsible for increasing the percentage of ovigerous females.

Reproductive traits of Macrobiotus hufelandi during a long-term field study with notes on Paramacrobiotus richtersi and Diphascon pingue (Eutardigrada)

We studied reproductive traits in populations of the eutardigrade species Macrobiotus hufelandi, Paramacrobiotus richtersi, and Diphascon pingue from a carpet of the moss Rhytidiadelphus squarrosus in the Black forest, Germany, over a period of 53 months. Specimens were fortnightly extracted, measured, and divided into dead and living individuals. The living specimens were divided into juveniles, ovigerous females (i.e. females with mature eggs and immature, but vitellogenetic eggs), and females with undifferentiated oocytes. Males were never found during the investigation period. For the most abundant species, M. hufelandi, it was shown that i) ovigerous females were found throughout the year; ii) reproductive activity (expressed as the percentage of ovigerous females in the total population) was highest from January to June, but peaks in these months varied considerably within the investigation period; iii) development of eggs may be considerably delayed compared with data obtained from cultures; iv) presence of ovigerous adults and juveniles was nearly opposite, i.e. the more adults the fewer juveniles were found, and a maximum of adults was followed by a maximum of juveniles with some delay and vice versa; v) number of oocytes, as well as length and percentage of ovigerous females relative to the total number of specimens appeared to be negatively correlated, whereas percentages of juveniles (&lt;260 μm in length) appeared to be positively correlated with temperature. Other correlations included humidity (number of oocytes, negative; percentage of juveniles, positive) and the sum of hours of sunshine (length and percentage of ovigerous females, negative; percentage of juveniles, positive). The relatively low numbers of P. richtersi and D. pingue collected during the investigation period did not allow a more detailed analysis, but here as well ovigerous females were found throughout the year.

Reproductive pattern in the caridean shrimp Gnathophylloides mineri Schmitt (Gnathophyllidae), a symbiont of sea urchins

ABSTRACT Caridean shrimp exhibit a wide variety of sexual and mating systems, and many species are well studied. Gnathophylloides mineri Schmitt, 1933 is a small, circumtropical symbiont of various species of sea urchins. Very little is known about the reproductive ecology of this species. Field surveys of a Jamaican G. mineri population showed that the reproduction occurred throughout the year, with a consistently high (>80%) percentage of ovigerous females in all seasons. The female: male sex ratio (1.31 : 1) was not significantly different than 1:1. Typically 1 to 3, and no more than 5, shrimp per urchin were observed at our field sites, a lower density than at other Caribbean locations where larger urchins support greater numbers of smaller individual shrimp. Gnathophylloides mineri Schmitt, 1933 occurred predominantly as pairs, and 85% of those pairs consisted of one male and one female. Such strong pair-bonding suggests the shrimp may be socially monogamous, unlike polygynous populations elsewhere t...

Populational and reproductive aspects of Southern &lt;i&gt;Macrobrachium acanthurus&lt;/i&gt; (Wiegmann, 1836) (Crustacea: Palaemonidae), Brazil

Macrobrachium acanthurus has a wide geographic distribution in America, mainly in rivers that flow into the Atlantic Ocean. Considering the economic interest in the Brazilian freshwater shrimp culture and its potential as a living resource, this study addresses the population and reproductive information of M. acanthurus that inhabit the north coast of São Paulo State. Individuals (N: 466,164 males and 302 females, with size ranging from 3.96 to 35.14 mm of carapace length) were captured with sieves (two people during 30 minutes) and traps (four hours after the nightfall) in April and October/2008 and in March/2009. Females were predominant in all sampled months; their ovaries showed changes in color and their size increased according to the developmental stage. The presence and percentage of ovigerous females in all sampled months indicated the possibility that the reproductive activity was continuous. The average fecundity (2299 ± 1653 eggs) found was directly related to the female’s size. The ovarian development occurred concomitantly with the eggs’ development, indicating successive spawning. It was observed that the eggs changed color and increased their volume independently of the female size. The absence of embryo loss during the incubation process may be speculated to be an efficient strategy developed by the ovigerous females, as a mechanism of parental care against the most common causes of egg loss.

Reproductive biology of Argis lar from the East Sea of Korea (Decapoda, Natantia)

We studied the reproductive biology of Argis lar from the East Sea of Korea, based on a total sample of 4172 shrimp collected over a 12 month period. The sample included 40 males (size range: 9.91-24.11 mm carapace length, CL), 2797 non-ovigerous females (size range: 7.22-38.33 mm CL), and 1335 ovigerous females (size range: 19.70-37.43 mm CL); size differed significantly among the three groups. Ovigerous females occurred during every month of the year, in varying percentages, with a minimum abundance of 2.48% in August; the extended reproductive period indicates that multiple spawnings occur during the year. All ovarian stages were present in non-ovigerous females, whereas only spent ovarian stages were present in ovigerous females. Two modes were present in the abundances of females at each ovarian stage. In the first mode, females at the mature ovarian stage were most abundant in September (61.98%) and females in the spent ovarian stage were most abundant in November (32.52%). In the second mode, females at the ripe ovarian stage were most abundant in December (62.96%) and females at the spent ovarian stage were most abundant in March (66.00%). The gonadosomatic indices of non-ovigerous females and ovigerous females varied significantly by month. The percentages of ovigerous females with eggs at different stages of development were: non-eyed eggs, 32.06%; eyed eggs, 25.69%; and hatching eggs, 42.05%. Females with hatching eggs occurred from November to June. The relationships between CL and ovary weight differed significantly between ovigerous females with eggs in the non-eyed and eyed stages. Our results indicate that the highest indices of reproductive potential (IRP) occurred in females in the 29.1-31.0 mm CL size class (IRP = 405).

Life cycle and population structure of the terrestrial isopod Hemilepistus klugii (Brandt, 1833) (Isopoda: Oniscidea) in Iran

The life cycle and population structure of Hemilepistus klugii were studied in a population in Varamin, Iran. The population was sampled monthly (or fortnightly during the breeding season) from February 2008 to June 2009 and a total of 7015 individuals, comprising 1069 males, 1079 females and 4867 juveniles, were collected. As in other Hemilepistus species, five distinct phenophases, namely pair formation, gestation, hatching, growth and stationary, were recorded during the life cycle of H. klugii. The overall sex ratio was 1 : 1 but varied over time. Ovigerous females were observed only in April, indicating a seasonal and very short breeding period. With a short lifespan after breeding, females demonstrated true semelparity. The mean cephalothorax width for ovigerous/post-ovigerous females was higher in 2008 than in 2009. These females attained the largest size in the population throughout the year. The number of eggs per female ranged from 28 to 147 (mean ± SE, 78 ± 1.8). There was a positive correlation between female size and fecundity. Recruitment occurred in late April and resulted in the highest population density in this month, whereas the lowest densities were observed during November to January. Despite a high percentage of ovigerous females carrying undeveloped eggs (72.3%), intramarsupial mortality was low (3.5%).

Population structure and reproductive period of whitebelly prawn Nematopalaemon schmitti (Holthuis 1950) (Decapoda: Caridea: Palaemonidae) on the southeastern coast of Brazil

The population biology of Nematopalaemon schmitti in the Ubatuba region on the northern coast of the state of São Paulo was characterized through analyses of the length-frequency distribution, sex ratio, reproductive period, and juvenile recruitment. The specimens were caught monthly from January 1998 to December 1999, from a shrimp boat equipped with double-rig trawl nets. A total of 1073 specimens were analyzed, and the sex and carapace length (0.1 mm) of each individual were noted. The analyzed specimens consisted of 152 juveniles, 437 adult males, 296 adult females, and 188 ovigerous females (OFs). The monthly distribution of N. schmitti by size classes revealed a stable population structure, with both juveniles and adults continuously present. This population showed a unimodal distribution; however, bimodality was identified in June 1998 and 1999 for males, and June 1998 and July 1998 and 1999 for females, probably related to recruitment pulses of juveniles. Sexual dimorphism was indicated by the presence of females in the larger size classes, probably because of their growth rate. The proportion between males and females differed from 1 : 1 in certain size classes and seasons of the year (χ 2, p < 0.05); in some situations, the females were more abundant than the males, or vice versa. No significant relationship was detected between the seasonal mean temperatures of the bottom water and the percentages of OFs and young, or for the relationship between these two groups (Spearman, p > 0.05). The continuous presence of OFs and young in the population suggests a pattern of continuous reproduction for N. schmitti in the Ubatuba region.

겨울철 동해 왕돌토 지역에 서식하는 대게자원 (Chionoecetes opilio) 출현 양상

An ecological investigation was conducted in winter from November 2007 to February 2008, around Wangdol Reef in the East Sea to analyze the population structure and fecundity of Chinoecetes opilio. The sex ratio was 30.11:69.89% (female:male) in November, 62.03:37.97% in December, 37.59:62.41% in January and 14.69:85.31% in February. Regression equations indicated highly positive relationships between size and weight parameters (carapace length, width, total weight). During the sampling period ovigerous females were continuously collected. The percentage of ovigerous females was 96% in November, 90.57% in December 89.80% in January, and 88.46% in February. The average number of embryos was 64,800. The regression equation between carapace width and the number of embryos was y = 2.6805x-0.9182 (R2 = 0.7166). Embryo volume increased as embryo development proceeded. The mean size of an embryo was 0.72 mm. Embryo volume ranged from 0.42 to 0.84 m3 during embryo developmental stages 1 to 3.

Evaluation of dietary microalgae for culture of the calanoid copepod Pseudodiaptomus pelagicus

A series of five experiments were conducted to evaluate the effects of various dietary microalgae on survival, reproduction, sex ratio, fecundity, time to first maturation, brood interval, brood size, total nauplii production, and population development of the calanoid copepod Pseudodiaptomus pelagicus. Three experiments utilized 10 reproductive pairs of adults cultured in 1 L beakers. In the first experiment, the microalga Isochrysis galbana (T-iso) was fed at five densities to determine the optimal density for production. In the second experiment, five microalgae, T-iso, Thalassiosira weissfloggi (Tw), Chaetoceros gracilis (Ch), Rhodomonas lens (Rh), and Tetraselmis suecica (Tet), were each fed at a carbon equivalency of 80,000 cells/mL of T-iso. In the third experiment, the same five microalgae were fed along with four mixed microalgae diets, consisting of T-iso/Tw and T-iso/Ch at two ratios, 50:50 and 75:25, all were fed at a carbon equivalency of 160,000 cells/mL of T-iso. The fourth experiment cultured individual pairs in 30 mL beakers to determine the effects of dietary microalgae on nauplii production, brood size, and brood interval. The fifth experiment cultured 100 early stage nauplii (N1–N3) until the population reached sexual maturity. The optimal density of T-iso was 160,000 cells/mL. At 80,000 cells/mL, Tw produced a significantly greater number of copepods than the other microalgal diets. In the 160,000 cells/mL experiment, total production with T-iso/Tw at 50:50 ratio was the highest and was significantly higher than all monoalgal diets except Rh. In general, the total number of copepods produced was greater with mixed algal diets than those attained with the monoalgal diets. Results of the nauplii growout experiment showed that the survival of nauplii to adult was highest with Rh and lowest with T-iso. Time to first maturity was significantly affected by dietary microalgae with T-iso being the slowest. The percentage of ovigerous females was significantly different among dietary microalgae, with T-iso and Ch exhibiting the lowest percentage. P. pelagicus can be successfully cultured with various monoalgal diets but results suggest that a mixed algae ration of T-iso and Tw will produce the greatest population growth.

Effect of bis(tributyltin) oxide on reproduction and population growth rate of calanoid copepod Schmackeria poplesia

A full life-cycle toxicity test, combined with histology, on calanoid copepod Schmackeria poplesia was used to study the effect of bis(tributyltin) oxide (TBTO). The results indicate no sex-specific differences in TBTO toxicity. Long-term mortalities of the copepods exposed to concentrations higher than 20 ng TBTO L−1 were significantly elevated compared with that of control, and larval development was inhibited when they were exposed to 40 and 60 ng TBTO L−1. The percentages of ovigerous females were reduced compared with the control (P<0.01) after 24 days exposure to concentrations higher than 10 ng TBTO L−1. Histological examinations suggest that exposure to TBTO might block the posterior end of the diverticula and inhibits the production of egg sacs. A modified Euler-Lotka equation was used to calculate a population-level endpoint, the intrinsic rate of natural increase (r m), from individual life-table endpoints, i.e. mortality rate, time of release of first brood, sex ratio, the fraction of ovigerous females among all females as well as the number of nauplii per ovigerous female. Apart from the highest TBTO concentration (60 ng L−1), where all females aborted their egg sacs, 20 ng TBTO L−1 was the only concentration that significantly decreased r m compared with that of control (an effect associated with decreased sex ratio). The results show that the S. poplesia is affected by prolonged exposure to low concentrations of TBTO. The full life-cycle toxicity test combined with histology experiments provides more integral understanding of the toxicity of endocrine disrupters.

Temperature-induced oviposition in the brachyuran crab Cancer setosus along a latitudinal cline: Aquaria experiments and analysis of field-data

Ovigerous females of Cancer setosus are present year-round throughout most of its wide range along the Peruvian/Chilean Pacific coast (2°S–46°S). However, their number of egg-masses produced per year remains speculative and as such has neither been considered in latitudinal comparisons of reproduction, nor for its fisheries management. In order to reveal the effect of temperature on egg-mass production and egg-development, female C. setosus were held in through-flow aquaria under natural seasonal temperature conditions (16–23 °C) in Antofagasta (23°S), Northern Chile (05/2005–03/2006; 10 months), and at three constant temperatures (12, 16, 19 °C) in Puerto Montt (41°S), Central Southern Chile (09/2006–02/2007; 5 months). Female crabs uniformly produced up to 3 viable egg-masses within 4 1/2 months in Antofagasta and in Puerto Montt (at 19 °C). The second egg-mass was observed 62.5 days (± 7.6; N = 7) after the oviposition of the first clutch and a third egg-mass followed 73.5 days (± 12.5; N = 11) later in Antofagasta (at 16–23 °C). Comparably, a second oviposition took place 64.4 days (± 9.8, N = 5) after the first clutch and a third, 67.0 days (± 2.8, N = 2), thereafter, at 19 °C in Puerto Montt. At the two lower temperatures (16 and 12 °C) in Puerto Montt a second egg-mass was extruded after 82.8 days (± 28.9; N = 4) and 137 days ( N = 1), respectively. The duration of egg-development from oviposition until larval hatching decreased from 65 days at 12.5 °C to 22.7 days at the observed upper temperature threshold of 22 °C. Based on the derived relationship between temperature and the duration of egg-development ( y = 239.3175e − 0.107 x ; N = 21, r 2 = 0.83) and data on monthly percentages of ovigerous females from field studies, the annual number of egg-masses of C. setosus was calculated. This analysis revealed an annual output of about one egg-mass close to the species northern and southern distributional limits in Casma (9°S) and Ancud (43°S), respectively, while at Coquimbo (29°S) about two and in Concepción (36°S) more than 3 egg-masses are produced per year.

Growth performance of the rotifers Brachionus plicatilis, B. ‘Nevada’ and B. ‘Cayman’ under different food concentrations

Numerical response experiments were conducted using three strains of the Brachionus plicatilis species complex. They are commonly used in aquaculture, and could also coexist in nature although this has not been studied yet. Brachionus plicatilis sensu stricto (s.s.), B. ‘Cayman’ and B. ‘Nevada’ were cultured at different concentrations of Nannochloropsis oculata (0–40 mg C l−1). Growth rate, egg female ratio (EF), fecundity and percentage of ovigerous females were determined at each food concentration. From the growth rate and EF, the egg development time and mortality rate were estimated using the Paloheimo equation. Monod curves with a threshold for zero growth described the relationship between growth rate and food concentration. The three strains had different growth rates at low (<0.04 mg C l−1) and high (>5.0 mg C l−1) food concentrations, but were similar at intermediate food levels. B. ‘Cayman’ had the highest maximum growth rate (1.57±0.07 d−1), whereas B. plicatilis s.s. had the less negative minimum growth rate and the highest maximum EF (0.96±0.02 eggs ind−1). These differences were attributed to the lowest egg development time of B. ‘Cayman’ (5.95±0.24 h) and the higher starvation resistance of B. plicatilis s.s. (84±12 h), respectively. B. ‘Nevada’ was the inferior competitor at high and low food concentrations due to the higher investment in body growth rather than reproduction. The outcome of competition in hatcheries is predicted to favor B. ‘Cayman’ under high food concentrations, whereas the three species may coexist under moderate food limitation.

Spatial distribution, density, and relative growth of &lt;i&gt;Microphrys bicornutus&lt;/i&gt; (Latreille, 1826) (Brachyura: Majidae) in five biotopes in a &lt;i&gt;Thalassia&lt;/i&gt; complex

Spatial distribution, population density, number of ovigerous females, and relative growth of Microphrys bicornutus were studied in an extremely shallow Thalassia complex (Buchuaco- Venezuela). Monthly sampling was undertaken in 5 different biotopes (zones) (July 1988 to December 1990). Zone 3 (coral rubble) was the least populated by M. bicornutus . The highest densities were found in Zones 1 (coral rubble and macro algae) and 4 ( Thalassia and calcareous algae). Crab size ranged between 1.86 and 35.40 mm (carapace length). The largest mean size was found in Zones 2 and 5, and the smallest in Zone 1. The least mean percentage of ovigerous females was found in Zone 3, and the highest in Zone 5. There were strong temporal fluctuations, with the absence of ovigerous females in the first months of each year. The biometric data showed that pre-pubertal males ranged from 1.80 to 24.20 mm carapace length, and post-pubertals from 15.16 to 26.15. Pre-pubertal females ranged from 3.16 to 20.25 and post-pubertals from 8.84 to 21.85. Zone 3 was the most inadequate biotope for M . bicornutus , as it had the lowest density and the least mean percentage of ovigerous females. Zone 4 was the most appropriate biotope. Temporal absence of ovigerous females and the small sizes of the crabs in Buchuaco could be due to extreme environmental conditions.

Reproductive biology of the spiny lobster, Panulirus Penicillatus, in the southeastern coastal waters off Taiwan

The reproductive biology of spiny lobster, Panulirus penicillatus, was studied based on 2,068 lobsters, ranging from 34.28 to 131.60 mm carapace length (CL), sampled in Taitung coastal waters from September 2003 to December 2004. The overall sex ratio approximated 1:1 (χ2 = 0.02, P > 0.05), but the monthly sex ratios in 2004 showed significant differences and males were predominant in sizes larger than 80 mm CL. Reproductive activity, assessed using histology, a gonadosomatic index and percentage of ovigerous females, indicated that the mature females could be found in every month and that the major spawning occurred from May to September. The presence of re-developing/re-ripe ovaries by month and size-specific spawning time suggest that larger mature females (>60 mm CL) spawn at least three times a year while smaller new mature females spawn at least once a year. For females, the estimated sizes at 50% physiological and functional maturity were (mean ± SE) 56.46 ± 0.56 mm CL and 66.63 ± 1.07 mm CL. The estimated sizes at functional maturity were between 72 and 74 mm CL for males. The number of eggs per spawning event (brood size, BS) was related to CL by the equation YBS = 2.4 × 10-3CL4.18 (r2 = 0.902, n = 12). Female lobsters with CL ranging from 60 to 80 mm made the greatest contributions to egg production because of their high brood size and active reproductive activity. A minimum legal size should be established for the fishery to protect egg production potential of lobster population in the southeastern coastal waters off Taiwan.

Biologia reprodutiva de Ligia exotica (Crustacea, Isopoda, Ligiidae) em Rio Grande, Rio Grande do Sul, Brasil

Com o objetivo de elucidar alguns aspectos da biologia reprodutiva de Ligia exotica Roux, 1828, duas populações que habitam o Estuário da Lagoa dos Patos (Molhe Oeste da Barra de Rio Grande e Ilha do Leonídeo) foram analisadas. A amostragem foi realizada quinzenalmente entre o verão/2003 e o inverno/2004. Os animais foram coletados manualmente durante uma hora. O período reprodutivo da espécie foi registrado para os meses de outubro a junho. Nenhuma fêmea ovígera foi observada de julho a setembro. No Molhe Oeste da Barra de Rio Grande, 5.376 indivíduos foram capturados (1.494 juvenis, 1.748 machos e 2.134 fêmeas, das quais 245 eram ovígeras). A proporção sexual estimada foi 0,78 (M:F). Para a análise da fecundidade, 178 fêmeas ovígeras com o marsúpio intacto foram analisadas. O comprimento total destas fêmeas variou entre 20,73 a 34,3 mm, e o número de ovos-embriões variaram de 33 a 142. O comprimento médio de primeira maturação sexual das fêmeas foi 24,65 mm e o número médio de ovos-embriões foi 88. Na Ilha do Leonídeo, 5.519 animais foram coletados (510 juvenis, 1.956 machos e 3.053 fêmeas, das quais 129 eram ovígeras). A proporção sexual foi 0,68 (M:F). Pequenas porcentagens de fêmeas ovígeras foram encontradas de setembro a maio, sendo a mais alta porcentagem observada no final de março. Neste local, 101 fêmeas ovígeras foram analisadas, com o comprimento total variando entre 17,62 a 28,61 mm e o número de ovos-embriões entre 25 e 113. O comprimento médio de primeira maturação sexual das fêmeas e o número médio de ovos-embriões foram, respectivamente, 21,43 mm e 73,8.