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The female of Haplostomides hibernicus (Scott and Scott, 1895) is fully redescribed on the basis of a single specimen living in the compound ascidian Polyclinum aurantium Milne Edwards, which was obtained at Strangford Lough in the Irish Sea in 1995. This copepod was collected by the author, together with specimens of H. scotti Chatton and Harant, 1924, from the same ascidian. The redescription confirms that the specimen of H. hibernicus is comparable in morphology to the copepods that Scott and Scott (1895) described as (?)Enterocola hibernica from Valentia Island and that Chatton and Brément (1910) redescribed as Aplostoma hibernica from Roscoff. The result of this study indicates that H. scotti is synonymous with (?)E. beaumontiScott and Scott, 1895, which was found together with (?)E. hibernica in an unidentified ascidian at Valentia Island.
This study has shown that Pontogammarus robustoides has a multivoltine life cycle in central Poland, with three generations per year (spring, summer, and autumn). Reproduction lasts from March/April until October, when the last breeding females are found. The first juveniles appear in May and are present in the population until the end of October. Spring and summer generations mature in a very short time (4–5 weeks). Females born in May and July start breeding at a body length of 8.5 mm, whereas the length of overwintering females breeding in spring ranges 11–18 mm. The number of eggs laid is exponentially correlated with the size of a female (r2= 0.89).
The average oxygen consumption of well-fed Waldeckia obesa individuals, whose average wet weight equals 318.3 mg is, 74.7 μL O2 ind−1 h−1 at the temperature 0°C. On average, 10-day-long starvation reduces the metabolism level by 36%, and 30-day-long starvation by 66%, compared to well-fed individuals. Investigations concerned the influence of 12 amino acids at the 10 mM concentration on W. obesa respiration. Amongst animals starved for 10 days, the addition of amino acids does not lead to statistically significant changes in metabolism rates, while amongst animals starved for 30 days, arginine leads to an 241% increase in metabolism rates. Glutamic acid constitutes about 10% of all amino acids in the body of W. obesa and more than 15% in the Nototenia neglecta fish, which is a food resource for this crustacean.
The feeding mechanisms of two species in the tanaidacean family Kalliapseudidae, Kalliapseudes macsweenyi Drumm and Psammokalliapseudes granulosus Brum, are elucidated by comparing gut contents, mouthpart movements, and feeding behavior. Kalliapseudes macsweenyi filter-feeds and possesses plumose setae on the chelipeds, maxillipeds, and maxillae. When building its burrows, P. granulosus scrapes detritus off sand grains by using the comb setae on the maxillae. It suspension-feeds when settled in its burrows by trapping detritus on the antennular setae. Both species feed primarily on detritus. Diatoms were the second most abundant food item in the foregut of K. macsweenyi. Respiration and cleaning behavior are also compared.
Fishery dependent trawl samples taken in spring prior to commercial shrimp trawling season in South Carolina were analyzed for annual relative abundance, sex ratios, and ovarian development of white shrimp, Litopenaeus setiferus, during 1980–2003. Fishery independent trawl samples were analyzed for relative abundance and ovarian development of female L. setiferus during the same period. Relative abundance varied greatly among years, and was thought to be strongly influenced by winter water temperature. The decade of the 1990s was a period of mild winters and high abundance of white shrimp in South Carolina. Biological observations about size and sex ratios of shrimp were consistent with past studies done along the southeastern Atlantic coast. Proportions of male shrimp in fishery dependent collections appeared to increase with advance of maturation of female shrimp. After spawning, numbers of male shrimp declined, suggesting that males are attracted to location of females prior to spawning, as has been postulated in published laboratory studies. Analyses of fishery independent samples indicated a slight delay in time of maturation of female shrimp during cool temperatures in spring; conversely, spring seasons with warm temperatures seemed to speed up maturation. This study should help elucidate the location of spawning areas for L. setiferus off South Carolina, in addition to its primary purpose of managing the shrimp fishery on a biological basis.
This study examined the circadian feeding cycles of two sympatric decapod prawns, Palaemonetes argentinus (Nobili, 1901) and Macrobrachium borellii (Nobili, 1896), as a coexistence mechanism. The work was done in some shallow lakes of the alluvial valley of the Paraná River (Santa Fe, Argentina). Both prawns consume similar food items, but they differ in their feeding times. Macrobrachium borellii stomach fullness was greater during night than day, whereas P. argentinus foraging activity occurred by day. Trophic niche breadth was wide and similar in both species during the day but was expanded in P. argentinus at night when M. borellii feeding activity increased. Niche overlap fluctuated without a definite pattern. Adaptive modifications of circadian feeding rhythms play an important role in the coexistence of these species.
Population characteristics such as population structure, growth, mortality, and size at sexual maturity of P. gravieri inhabiting warm temperate waters were investigated using size-frequency distribution data (January 1999 to December 2000). Sexual differences for carapace length/total weight and carapace length and total length were statistically significant in the intercept of the regressions in the former relationship and the slope in the latter, respectively. Population size based on size-frequency distribution between female and male and between two years were described. Population density was high in March and April during two years of sampling. Sex ratio was biased toward females for most of the months sampled. Growth was continuous and seasonally oscillated throughout the year. Adult females were larger and grew faster than males. The von Bertalanffy growth parameters for two-year pooled samples between females and males were estimated as L∞ = 23.20, K = 0.8, C = 0.4, WP = 0.1, Rn = 0.269, t0 = −0.016 (females); L∞ = 18.59, K = 0.704, C = 1.00, WP = 0.2, Rn = 0.326, t0 = −0.023 (males), respectively. Instantaneous total mortality (Z) for two-year pooled samples were estimated by the equation y = −3.92x 11.89 (n = 10, r = 0.920) for females and y = −2.41x 10.57 (n = 9, r = 0.976) for males, respectively; sexual maturity was estimated to be at 7.89 mmCL (carapace length).
The population dynamics, growth, and reproduction of the deep-water pandalid shrimp Plesionika martia were studied in the eastern Mediterranean Sea. Samples were collected monthly (July 1999–June 2000) at a depth range of 440–600 m between Zakynthos Island and Peloponnissos (eastern Ionian Sea, Greece). Additional samples were taken in April and May 2001. Size-frequency distribution revealed that mean female size consistently exceeded that of males throughout the year (CL range: 8–23.5 mm and 9.3–29.1 mm for males and females, respectively). Smaller individuals of both sexes occurred only at depths less than 500 m. Mean size of both sexes increased linearly with depth, whereas a less prominent trend of sex ratio in favor of females by depth was observed. The overall yearly and the monthly sex ratio were in favor of females except during winter, when the two sexes were equally represented. Carapace length–wet weight relationships showed negative allometry, for both males and females. Ovigerous females occurred year around, although the main reproductive season extended from April to October. The smallest ovigerous female was 11.8 mm CL, whereas the size at 50% sexual maturity (CLm50) was estimated as 16.16 mm. Fecundity and reproductive output were found loosely related to shrimp size. The von Bertalanffy growth curve parameters were estimated as: L∞ = 30.6 mm, k = 0.31 year−1 in females and L∞ = 28.2 mm, k = 0.53 year−1 in males. Regarding the major life history traits, P. martia from the eastern Ionian seemed to conform to those in other Mediterranean areas. Nevertheless, some population differences exist, which can be related to the oligotrophic conditions and the lack of fishing pressure in the studied area.
Two new crangonid shrimps of the genus Metacrangon, M. proxima and M. miyakei, are described and illustrated from Japan. The former species, from Sagami Bay, Pacific coast of Japan, is very similar to M. variabilis (Rathbun, 1902) from the Bering Sea, but it is distinguished from M. variabilis by the shape of the rostrum, of the stylocerite of the antennule, of the scaphocerite, and of the palm of the first pereopod, the armament of the carapace, and the disposition of the dorsolateral spines of the telson. The latter species, which was previously reported by Miyake (1982) under the name of M. angusticauda (De Haan, 1849) as an unidentified species from off Tango Peninsula, Sea of Japan, appears unique in the genus in having an additional median spine between two principal median spines.
The gilgie, Cherax quinquecarinatus, a freshwater crayfish endemic to southwestern Western Australia, occupies a wide range of permanent and temporary aquatic environments. Reproductive and population biology parameters were determined in Bull Creek, southwestern Western Australia. Crayfish were collected monthly from May 2002 to April 2003. The seasonal von Bertalanffy growth curve, fitted for the first 14 months of life for female and male C. quinquecarinatus, had respective curvature parameters (K) and asymptotic orbital carapace lengths OCL∞ (CL∞) of 0.29 and 59.6 (71.2) mm for females and 0.25 and 73.8 (87.0) mm for males, respectively. This equates to OCLs (CLs) of females and males at age 12 months of 14.7 (19.2) and 14.1 (18.4) mm, respectively. Cherax quinquecarinatus was found to mature at a relatively small size, with the length at which 50% of individuals mature L50 for females and males being 18.8 and 24.5 mm OCL (24.1 and 30.9 mm CL), respectively. The majority of C. quinquecarinatus thus first spawned at the end of their second year of life. The potential (ovarian) and pleopodal fecundities of C. quinquecarinatus were relatively low compared to other freshwater crayfish species of similar size, being 81.7 (± 5.93 S.E.) and 77.1 (± 13.76 S.E.), respectively. Cherax quinquecarinatus underwent an extended spawning period, from late winter to late summer (i.e., August to February), with three spawning events facilitated by short brood and rapid gonadal recovery periods, traits consistent with other crayfish species able to exist in temporary environments. Estimates of total mortality (Z) were relatively high at 2.34 and 1.95/year based on age-converted catch curves for females and males, respectively, with a considerable proportion of this attributed to fishing mortality (exploitation rates of 0.76 and 0.75 for females and males, respectively). Cherax quinquecarinatus underwent a life-history strategy that showed characteristics of both a summer (r- strategist) and winter (K-strategist) brooder.
This paper describes the reproductive biology and growth of Ibacus alticrenatus, I. brucei, and I. chacei from the east coast of Queensland, Australia. Reproductive cycles, sizes at maturity, sex ratios, morphological data, egg sizes, brood fecundities, length-frequency distributions, and growth parameters are described. Ibacus chacei numerically dominated both the commercial and research charter samples and were followed by I. brucei and I. alticrenatus in abundance respectively. Seasonal reproductive data indicated that I. brucei and I. chacei have an annual cycle of reproduction, with oviposition and hatching occurring earlier and over a shorter period in I. brucei. Gonadal maturation in ovigerous I. chacei suggested that more than one brood could be produced in a spawning season; however, reproductive activity was geographically restricted. Carapace lengths of ovigerous lobsters ranged 38.2–52.0 mm for I. alticrentatus, 44.6–69.7 mm for I. brucei, and 53.7–76.2 mm for I. chacei. Brood fecundity was size dependent and highest in I. brucei (2049–61,339) but markedly lower in I. chacei (2117–28,793) and I. alticrenatus (1734–14,762). Egg size in all three species was independent of carapace length, positively related to developmental stage, and ranged 0.94–1.29 mm for I. alticrentatus, 0.73–1.01 mm for I. brucei, and 1.02–1.37 mm for I. chacei. Monthly length-frequency distributions for I. chacei displayed marked multi-modality and indicated a prolonged recruitment period with moulting occurring 3–4 times within their first year post-recruitment. Growth curves of I. chacei indicated that females reach sexual maturity 1.7–2 yrs post settlement and that individuals approached their Lmax within 5–7 yrs. These results are discussed in relation to comparisons between each species and other members of the Scyllaridae family, and provide invaluable biological information for the development of sustainable management strategies for Queensland's Ibacus species.
Commercial fishers of blue swimmer crabs in Western Australia use ice-water slurries to pacify crabs and thereby minimise the damage caused by on-board handling. This study investigated the effect of exposure to ice-water slurries on the mortality and recovery rate of male and female blue swimmer crabs, and on egg loss and the viability of the surviving larvae of ovigerous females. The temperatures (0–15°C) and durations (15 seconds to 30 minutes) of exposure in the trials were within the range used by commercial fishers in order to determine the combination of temperature and duration that would pacify the crabs while minimising recovery time. Exposure to ice-water slurries did not kill the crabs except in the most extreme treatments, e.g., 0°C for 30 minutes. However, both temperature and exposure time had a significant effect on recovery time, which decreased with increasing temperature. Treatments above 6°C had little impact, with crabs recovering instantly, even with 60-second exposure. Exposure to low temperatures did not result in significant egg loss, although females may lose part of their egg mass during on-board handling. Similarly, the effect on the developing larvae was not apparent unless the ovigerous female died. Although exposure of ovigerous and nonovigerous crabs to ice-water slurries had only minimal immediate effects, exposure to 6°C for 30 seconds is recommended, as it adequately pacifies crabs for handling and results in a minimum recovery period which may be important in minimising secondary effects.
The two forms of Hemigrapsus penicillatus (de Haan, 1835), recently distinguished on the basis of electrophoresis and differences in the size of the setal patches on the male chelae, are here recognized as two distinct species. The individuals having smaller setal patches are H. penicillatus, whereas those with larger setal patches are described herein as a new species. Living and fresh material of the two species are also clearly separated by the size and distribution of dark spots on the cephalothorax, abdomen, third maxillipeds, and chelipeds. Morphology of the male first pleopod is different between the two species. Females of the two species are morphologically identical and cannot be easily separated once colour has faded.
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; kmale = 0.28; kfemale = 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.
The ecology of two species of tree-climbing crabs, Malagasya antongilensis (Rathbun, 1905) (Potamonautidae) and Labuanium gracilipes (H. Milne Edwards, 1853) (Sesarmidae), collected from container microhabitats (phytotelmata) in rainforest in the Masoala Peninsula, Madagascar, is described. This is a rare report of a tree-climbing phytotelmic sesarmid crab living in the rainforest canopy, and the first record of a species of true freshwater crab in the canopy, albeit at a relatively low height. The difficult-to-access rainforest canopy surveys were made as part of the Canopy Raft Program (Radeau des Cimes). The occurrence of crabs in water-filled plant containers in rainforest habitats is discussed.