Mud Crab Rhithropanopeus Harrisii Research Articles

A long-term study of the effects of water-soluble fractions of No. 2 fuel oil on the survival, development rate, and growth of the mud crab Rhithropanopeus harrisii

Mud crabs, Rhithropanopeus harrisii (Gould), were exposed continuously for 6 months after hatching to water-soluble fractions (WSF) of No. 2 fuel oil. Survival, growth and development rate were monitored during this time. The zoeal stages were the most sensitive to fuel oil. A 20% WSF (0.36 ppm total naphthalenes, 1.26 ppm total hydrocarbons) was acutely toxic to these stages. Of the zoeal stages, the first stage appeared to be the most sensitive. The combined duration of the 4 zoeal stages was significantly increased by increasing WSF exposure concentrations. The megalopa and crab stages were not particularly sensitive to continued petroleum hydrocarbon exposure, particularly when compared to zoeal stages. However, mean duration of the megalopa and first crab stages was significantly affected by oil exposure. Individuals which survived the highest exposure concentrations as larvae appeared to grow larger during the crab stages, so that at the end of 6 months comparably staged crabs were equal to or larger than both control crabs and those exposed to low WSF concentrations. Stage distributions at the end of 6 months showed no differences due to WSF exposure. Sex ratios, which could be determined at the end of 6 months, were approximately 1, indicating no sex-related differential sensitivity to WSF exposure, at least as larvae or juveniles. The data indicate that these crabs possess considerable ability to recover from the effects of chronic sublethal exposure to petroleum hydrocarbons. The most deleterious effects of oil pollution on this species may be due to its impact on larval recruitment into the adult population.

Effects of a juvenile hormone mimic on male and female gametogenesis of the mud-crab Rhithropanopeus harrisii (Gould) (Brachyura: Xanthidae).

1. Effects of ingestion and topical application of 1.30 ppm methoprene, an insect juvenile hormone (JH) mimic, include gametogenesis disorders in both male and female mud-crab Rhithropanopeus harrisii. 2. Progressive inhibition of vitellogenesis and stimulation of spermatogenesis take place after a short exposure time (12-15 days), whereas a longer period (between 30 to 45 days) promotes inhibition of both spermatogenesis and vitellogenesis. Such modifications demonstrate the chemosterilizing action of methoprene on crustaceans. 3. Stoppage of vitellogenesis is characterized by a blockage of oocytes at terminal previtellogenesis and proliferation of the follicle cells involved in vitellogenic oocyte lysis. Spermatogenic degeneration begins with the amalgam of spermatocyte clusters in meiotic prophase and pycnosis of gonia. 4. Analogies between these results and those obtained from experiments involving androgenic gland implantations or the consequences of their hyperfunctioning are discussed.

Effects of the juvenile hormone mimic ZR-512 (Altozar®) on larval development of the mud-crab Rhithropanopeus harrisii at various cyclic temperatures

Effects of the juvenile hormone (JH) mimic hydroprene (Altozar®: ZR-512), which exhibits high activity against Lepidoptera, were studied on the larval development of the mud-crab Rhithropanopeus harrisii (Gould) (Brachyura: Xanthidae). Larvae reared in 20‰ S at 3 cycles of temperature of 20° to 25°C, 25° to 30°C and 30° to 35°C, were exposed to 0.01, 0.1 and 0.5 ppm hydroprene from hatching to the first crab stage. Larvae were also exposed to 0.1 and 0.5 ppm hydroprene only from the megalopa stage to the first crab stage. When larvae were treated with hydroprene throughout larval life, survival was significantly reduced with increasing concentrations of the compound at all temperature cycles. Synergistic effect between hydroprene and temperature on survival of zoeal larvae was not observed. On the average there was 11% less survival in the zoeal stages at the 0.01 ppm concentration. of hydroprene than in the control, an additional reduction of 13% occurred at 0.1 ppm, and finally there was a further decrease of 46% at 0.5 ppm hydroprene. Significant decrease in survival in the megalopa stage occurred only in the 0.5 ppm concentration of hydroprene at the lowest temperature cycle when larvae were exposed to the compound from hatching. When larvae were treated with hydroprene only within the megalopa stage, a significant reduction in survival was not observed. First-stage zoeae were the most sensitive of the larval stages to hydroprene. Duration of zoeal development was significantly delayed at 0.5 ppm hydroprene at the two lower temperature cycles, whereas in the megalopa stage the delay began at the 0.1 ppm level at all 3 temperature cycles when larvae were exposed to hydroprene from hatching. A significant delay was also observed at 0.1 ppm hydroprene at the two lower cycles when larvae were exposed to hydroprene only in the megalopa stage; at 30° to 35°C a significant delay was observed only at the 0.5 ppm level. The results show that metamorphosis to the first crab stage was not inhibited at the 0.5 ppm level of hydroprene or lower. Reduction in survival and increase in duration of larval development were presumably related to stress conditions caused by hydroprene. The results also suggest an interaction between temperature and hydroprene on survival of megalopa larvae and duration of larval development.

Effects of the juvenile hormone mimic ZR-515 (Altosid®) on larval development of the mud-crab Rhithropanopeus harrisii in various salinities and cyclic temperatures

Effects of 0.01, 0.1 and 1.0 ppm methoprene (Altosid®: ZR-515), a juvenile hormone (JH) mimic which shows high activity against some economically important insect pests, especially Diptera, were tested on larvae of the mud-crab Rhithropanopeus harrisii (Gould) (Brachyura: Xanthidae) from hatching to the first crab stage under optimum and stress conditions of a number of salinities and cyclic temperatures. There was a significant reduction in survival of zoeal larvae with increasing concentrations of methoprene in nearly all combinations of salinity and temperature. On the average there was 9% less survival in the 0.01 ppm concentration of methoprene than in the control, and in the 0.1 ppm concentration the survival was further reduced by another 16%. At 1.0 ppm methoprene no larvae survived beyond the first zoeal stage under optimum conditions or under stressful combinations of salinity and temperature. Except at 0.2 ppm in 27.5% S, survival of the megalopa was not significantly reduced in 0.01 or 0.1 ppm methoprene in any salinity or temperature, although the percentage of abnormal megalopa increased under stress conditions. The first zoeal stage was the most sensitive of the larval stages to methoprene as well as to salinity and temperature stress. The duration of zoeal development was significantly lengthened with an increase in concentration of methoprene under nearly all conditions of salinity and temperature. The JH mimic had, however, no significant effect on the duration of megalopa development. A significant synergism between methoprene, salinity and temperature was not observed. It can be concluded from the results that methoprene does not inhibit metamophosis of R. harrisii larvae at the 0.1 ppm level or lower. Reduction in survival of zoeal stages and increased duration of zoeal development with increasing concentrations of methoprene are presumably related to stress.

Synergistic effects of cadmium and salinity combined with constant and cycling temperatures on the larval development of two estuarine crab species

The developmental stages from megalopa to third crab of the blue crab Callinectes sapidus Rathbun were tested in 12 combinations of cadmium (0, 50, and 150 ppb) and salinity (10, 20, 30, and 40‰) at 25°C. A reduction in survival and a significant delay in development from megalopa to third crab occurred within each salinity regime in 50 ppb compared with the control. Comparison of the delay in development within each salinity regime revealed that the sublethal effect of cadmium was most pronounced in the salinities normally preferred by C. sapidus. A similar comparison within each cadmium concentration, however, showed that the developmental time from megalopa to third crab was approximately the same irrespective of salinity. The developmental stages from hatch to first crab of the mud-crab Rhithropanopeus harrisii (Gould) were examined in 63 combinations of cadmium (0, 50, and 150 ppb), salinity (10, 20, and 30‰), constant temperature (20°, 25°, 30°, and 35°C) and cycling temperature (20° to 25°C, 25° to 30°C, and 30° to 35°C). The results indicated that cycling temperatures may have a stimulating effect on survival of the larvae compared to constant temperatures, both in the presence and in the absence of cadmium. Effects of cadmium and salinity and their interaction on the survival of the larvae from zoeae to megalopa were documented at most of the temperatures by analyses of variance. The zoeal larvae were more susceptible to cadmium than the megalopa. Effects of different combinations of cadmium and salinity on the duration of larval development were assessed by a t-test.

The effect of salinity and cyclic temperature on larval development of the mud-crab Rhithropanopeus harrisii (Brachyura: Xanthidae) reared in the laboratory

Larvae of Rhithropanopeus harrisii (Gould) were reared from hatching to the first or second crab stages in 11 combinations of salinities and cyclic temperatures (5, 20, and 35‰ S at 20° to 25°C, 25° to 30°C, and 30° to 35°C; 25‰ S at 20° to 25°C and 30° to 35°C). The larvae survived to the megalops and first crab stages in all salinities and cycles of temperature other than 5‰ S at 30° to 35°C. The best survival to the megalops (94%) and first crab (90%) stages occurred in 20‰ S, 20° to 25°C. In all other combinations of salinities and temperatures there was a reduction in survival to the first crab stage. The duration of the larval stages was affected significantly by temperature, whereas the effect of salinity on the mean days from hatching to the first crab stage was not consistent at the different temperature cycles. Development to the first crab stage required the shortest time in 20‰ S, 30° to 35°C (mean 12.3 days), and the longest time in 5‰ and 35‰ S, 20° to 25°C (mean 22.6 days and 21.6 days, respectively). Megalops larvae reared in 35‰ S at all cycles of temperature, as well as larvae in 20‰ and 25‰ S, 30° to 35°C, showed a high percentage of abnormality, with the highest percentage occurring in 35‰ S, 30° to 35°C. It appears that larval development of R. harrisii is strongly influenced by environmental factors and not solely related to genetic differences.

Fourth European Marine Biology Symposium.

Editor's foreword and opening address Part I. Theme A: The Biology of Marine Invertebrate Larvae Section 1. Field Observations: 1. The dispersal of the larvae of shoal-water benthic invertebrate species over long distances by ocean currents 2. Transport of bivalve larvae in a tidal estuary 3. Observations on the occurrence of planktonic larvae of several bivalves in the Northern Adriatic Sea 4. Comparative investigations of the development of epibenthic communities from Gloucester, Massachusetts to St Thomas, Virgin Islands 5. Settlement of mussel larvae, Mytilius edulis, on suspended collectors in Norwegian waters Section 2. Experiments on Behaviour and Distribution: 6. On the ecology of young Idotea in the Baltic 7. Choice of algae by larvae of Spirobis, particularly of Spirorbis spirobis 8. Settlement and orientated growth in epiphytic and epizoic byozoans 9. Settlement and growth pattern of the parasitic barnacle Pyrgoma anglicum 10. Electrophotetic examination of partially purified extracts of Balanus balanoides containing a settlement inducing factor 11. The biology of larvae of Ophilitaspongia seriata from two North Wales populations 11. Host selection and ecology of marine digenean larvae Section 3. Growth, Development and Fine Structure: 12. Effet de la temperature sur le developpement endotrophe des pluteus 13. La forme elliptique de la relation temperature-duree de developpement embryonnaire chez les copepodes pelagiques et ses propietes 14. The effect of cyclic temperatures on larval development in the mud-crab Rhithropanopeus harrisii 15. Les veligeres planctoniques de Prosobranches de la region de Banyuls-sur-Mer (Mediterranee occidentale): phylogenie et metamorphose 16. Concerning the fourth antennulzr segment of the cypris larva of Balanus balanoides 17. The fine structure of the trochophore of Harmothoe imbricata 18. Developpement larvaire de Microspio mecznikowianus 19. Some morphological changes that occur at the metamorphosis of the arvae of Mytilius edulis 20. The histology of the larva of Ostrea edulis during metamorphosis 21. Transient larval glands in palaemonetes 22. Spicule formation and corrosion in recently metamorphosed syon ciliatum (O. Fabricus) Part II. Theme B: Light in the Marine Environment Section 1. Measurement of Illumination and its Influence in Submarine Environment: 1. The measurement of inshore submarine irradiation 2. Continuous recording of underwater light in relation to Laminaria distribution 3. Seasonal growth of Laminaria hyperborea under recorded underwater light conditions near Helgoland 4. The effect of light on the growth of algal spores 5. Light quality and the photomorphogenesis of alge in marine environments 6. Studies on the responses of marine phytoplankton to light fields of varying intensity 7. Light and the distribution of organisms in a sea cave 8. Light conditions and shade seeking populations among algal settlements 9. Responses of the larvae of Diposoma listerianum to light and gravity 10. Food searching potential in marine fish larvae 11. A new light trap for plankton 12. Responses to light of Asterias rubens 12. Diurnal rhythms in snails and starfish 13. Orientation to light and the shading response in barnacles 14. The light sensitivity and light environment of Corophium volutator (abstract only) 15. La lumiere et le declenchement de la ponte chez Ciona intestinalis 16. Light controlled swarming in the polychaete Autolytus (abstract only) 17. Light and gonad development in Pontoporeia affinis Index.

Absence of sterol synthesis in larvae of the mud crab Rhithropanopeus harrisii and of the spider crab Libinia emarginata

A dietary requirement for sterols in crustacean larvae was established by the use of isotopic tracer techniques. Larvae of the mud crab Rhithropanopeus harrisii and larvae of the spider crab Libinia emarginata were exposed to acetate-14C or mevalonate-14C. Radioanalysis of the fatty acids of each species indicated sufficient incorporation of acetate for lipid synthesis. No radioactivity was detected in the sterols of animals exposed to either acetate-14C or mevalonate-14C. It was concluded that R. harrisii and L. emarginata larvae are unable to synthesize sterols from acetate or mevalonate and, therefore, require them in their diet.