Relationships of Epibiotic Fouling and Mortalities of Eggs of the Dungeness Crab (Cancer magister)

1976 ◽  
Vol 33 (12) ◽  
pp. 2849-2853 ◽  
Author(s):  
William S. Fisher
Keyword(s):  
Ultraviolet Irradiation ◽  
Laboratory Experiments ◽  
Sea Water ◽  
Close Association ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
Egg Masses ◽  
Chemotherapeutic Treatment

This study describes the close association of epibiotic microbial fouling on the eggs of Cancer magister and egg mortalities. Laboratory experiments showed that nutrient enriched sea water increased the number of measurable filaments on the egg surface and increased the number of egg mortalities. Chemotherapeutic treatment of the sea water decreased the number of filaments and mortalities. The use of antibiotics decreased the number of mortalities while the number of filaments steadily increased, suggesting that antibiotic-sensitive, nonfilamentous forms may be substantially responsible for mortalities caused by microbial fouling. Darkness and ultraviolet irradiation of the sea water had no significant effects on filaments or egg mortalities. Both filamentous fouling and egg mortalities described exponential declines with increased depths into the egg masses.

First Cohort of Young-of-the-year Dungeness Crab, Cancer magister, Reduces Abundance of Subsequent Cohorts in Intertidal Shell Habitat

1993 ◽  
Vol 50 (10) ◽  
pp. 2100-2105 ◽  
Author(s):  
Miriam Fernandez ◽  
David Armstrong ◽  
Oscar Iribarne
Keyword(s):  
Laboratory Experiments ◽  
Oyster Shell ◽  
Field Observations ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
First Instar ◽  
Alternative Hypotheses ◽  
Young Of The Year

Arrival and settlement of successive cohorts of Dungeness crab, Cancer magister, megalopae were observed in Grays Harbor, Washington, in 1991. The first cohort of megalopae entered the estuary between May 15 and 20 and settled in ("occupied") previously constructed artificial, intertidal oyster shell habitats at densities ranging from 155 to 196 first instar juvenile (J1) crabs∙m−2. Subsequently, a second set of shell habitats was constructed that did not contain crabs of the first cohort ("unoccupied"). Between June 15 and 18, when crabs of the first cohort were a mix of second and third instars, a second cohort of megalopae settled in both occupied and unoccupied shell habitat at respective J1 crab densities of 9–37 and 168–298 crabs∙m−2. The possible roles of cannibalism, competition, and conspecific avoidance are proposed as alternative hypotheses to explain significantly lower density of the second cohort in shell habitats previously occupied by larger conspecifics of the first cohort. Based on laboratory experiments, we suggest that cannibalism is a plausible explanation of our field observations.

Effects of the Insecticide Sevin on Various Stages of the Dungeness Crab, Cancer magister

1970 ◽  
Vol 27 (1) ◽  
pp. 93-104 ◽  
Author(s):  
David V. Buchanan ◽  
Raymond E. Millemann ◽  
Nelson E. Stewart
Keyword(s):  
Sea Water ◽  
Field Application ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
Egg Hatching ◽  
Growth And Survival ◽  
Life History Stages ◽  
And Control ◽  
Control Survival ◽  
Early Larvae

Of the life-history stages of the Dungeness crab, Cancer magister, the early larvae are more sensitive to Sevin than are juveniles and adults. A concentration of 1.0 mg/liter did not affect egg hatching but prevented molting of all prezoeae to zoeae. The concentration that killed 50% of the first stage zoeae during a 96-hr exposure (96-hr EC50 for death) was estimated to be 0.01 mg/liter. Few zoeae were killed in 24 hr by 82.0 mg/liter, but the 24-hr EC50 for death within 15 days after the exposure was estimated to be 0.015 mg/liter. The 24-hr EC50 for cessation of swimming, which was not always permanent, was 0.0065 mg/liter. Survival of zoeae after 25 days exposure to concentrations of 0.0001, 0.00032, 0.001, 0.0032, and 0.01 mg/liter were 83, 60, 69, 21, and 0%, respectively, and control survival was 79%. Molting was delayed at a concentration as low as 0.0001 mg/liter.Young juvenile crabs are more sensitive to Sevin than are older juveniles or adults. The 24-hr EC50's for death or irreversible paralysis were estimated to be 0.076 and 0.35 to 0.62 mg/liter for second and ninth stage juveniles, respectively. The behavior, growth, and survival of juvenile crabs were not affected when the animals were exposed to 0.032 mg/liter of Sevin for 24 hr and then held in clean sea water for 44 days. The 24-hr and 96-hr EC50's for death or irreversible paralysis were 0.49 and 0.26 mg/liter, respectively, for adult crabs. After eating cockle clams that had just been exposed for 24 hr to 1.0, 3.2, and 10.0 mg/liter of Sevin, 22, 77, and 100% of adult crabs, respectively, were irreversibly paralyzed within 6 hr. The significance of these findings in field application of Sevin to control oyster pests and predators is discussed.

Therapeutic Treatment for Epibiotic Fouling on Dungeness Crab (Cancer magister) Larvae Reared in the Laboratory

1977 ◽  
Vol 34 (3) ◽  
pp. 432-436 ◽  
Author(s):  
William S. Fisher ◽  
Richard T. Nelson
Keyword(s):  
Phaeodactylum Tricornutum ◽  
Sea Water ◽  
Chemotherapeutic Agent ◽  
Larval Survival ◽  
Antibiotic Activity ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
Larval Stages ◽  
Reasonable Evidence ◽  
Egg Stages

This study shows that larvae of the Dungeness crab (Cancer magister Dana) reared in the laboratory are susceptible to epibiotic microbial infestation similar to that described for eggs of the same species. Larval survival in the laboratory was increased by increased additions of antibiotics to the sea water; however, the chemotherapeutic agent, malachite green, was unsuccessful due to its toxicity to the sensitive larval stages. The addition of the diatom Phaeodactylum tricornutum was beneficial to larval survival in the light but detrimental in dark conditions, supporting the suggestion of a photosynthetic excretion from the algae capable of antibiotic activity. Chronic antibiotic treatment was observed to reduce the size of the larvae. Demonstration of larval susceptibility to epibiotic microbial infestation in the laboratory coupled with its occurrence on egg stages in nature provides reasonable evidence that the disease can occur on larval stages in nature.

Carcinonemertes errans and the Fouling and Mortality of Eggs of the Dungeness Crab, Cancer magister

1979 ◽  
Vol 36 (11) ◽  
pp. 1319-1324 ◽  
Author(s):  
D. E. Wickham
Keyword(s):  
Key Words ◽  
Causative Agent ◽  
Laboratory Experiments ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
Egg Mortality ◽  
Field Samples

Laboratory experiments analyzing the correlation between epibiotic fouling and mortality of the eggs of the Dungeness crab, Cancer magister Dana, reveal that both can result from predation on crab eggs by the nemertean Carcinonemertes errans Wickham. Fouling appears to be stimulated by the release of yolk material into the egg clutch through worm feeding and defecation. Significant correlations exist between worm density and both fouling and mortality in field samples. The ranking of the correlations between these three parameters suggest that nemertean activity is the causative agent and that fouling is only incidentally correlated to egg mortality through its correlation to worm density. Key words: Carcinonemertes errans, Cancer magister, crab-egg fouling, crab-egg mortality

Population Structure of Dungeness Crab (Cancer magister) in British Columbia

2008 ◽  
Vol 27 (4) ◽  
pp. 901-906 ◽  
Author(s):  
Terry D. Beacham ◽  
Janine Supernault ◽  
Kristina M. Miller
Keyword(s):  
British Columbia ◽  
Population Structure ◽  
Dungeness Crab ◽  
Cancer Magister

Eco-Physiological Studies of an Intertidal Crustacean, Pollicipes Polymerus (Cirripedia, Lepadomorpha)

1972 ◽  
Vol 57 (1) ◽  
pp. 83-102
Author(s):  
H. J. FYHN ◽  
J. A. PETERSEN ◽  
K. JOHANSEN
Keyword(s):  
Water Loss ◽  
Volume Regulation ◽  
Free Amino ◽  
Heat Load ◽  
Laboratory Experiments ◽  
Sea Water ◽  
Physiological Responses ◽  
The Body ◽  
Air Exposure ◽  
Pollicipes Polymerus

1. Physiological responses to environmental stresses of the intertidal cirriped Pollicipes polymerus have been studied by combined field and laboratory experiments. 2. The body temperature of air-exposed animals is always lower than expected from the heat load. Evaporation from the peduncle is responsible for the heat loss. 3. The rate of water loss by evaporation from the peduncle cuticle is 1.5 µl/cm2 h mmHg both at 21 and 27 °C. The transpiration is proportional to the saturation deficit of the air. The water loss from the capitulum is negligible in comparison to that from the peduncle. 4. The haemolymph osmolality of animals in the field increases during exposure to sunshine and decreases during exposure to rain. The increase in haemolymph osmolality during desiccation is equal to that calculated from the decrease in body water. The water loss during air exposure is adequately replaced during submersion, probably by osmosis. 5. Pollicipes is an osmoconformer but is 5-20 m-osmoles hyperosmotic. It tolerates sea-water dilutions down to about 50%. The hyperosmolality seems to be balanced by a high internal hydrostatic pressure. 6. An excretory activity is observed. The excretion is isosmotic to the haemolymph and is possibly an ultrafiltrate of the latter. 7. The muscle cells show volume regulation, but free amino acids seem to be unimportant in regulation of intracellular osmolality. The concentration of ninhydrinpositive substances in the muscle tissue is about 200 mM for animals in full strength sea water.

An Analysis of Acid-Base Disturbances in the Haemolymph Following Strenuous Activity in the Dungeness Crab, Cancer Magister

1979 ◽  
Vol 79 (1) ◽  
pp. 47-58
Author(s):  
D. G. McDONALD ◽  
B. R. McMAHON ◽  
C. M. WOOD
Keyword(s):  
Lactate Concentration ◽  
Dungeness Crab ◽  
Acid Base ◽  
Cancer Magister ◽  
Rapid Release ◽  
Strenuous Activity ◽  
Lactate Levels ◽  
Acid Base Disturbance ◽  
Base Disturbance

Enforced activity causes a marked depression of haemofymph pH in Cancer magister. Both lactate concentration and PCOCO2 of the haemolymph are elevated immediately following exercise but resting PCOCO2 is restored within 30 min whereas resting lactate levels are not restored for at least 8 h. The haemolymph acid-base disturbance is caused largely by elevated haemolymph lactate levels but a Davenport analysis based on measurements of pH and total CO2 reveals a marked discrepancy between the amount of metabolic acid buffered by the haemolymph and the lactate anion concentration. This appears due to a more rapid release of lactate from the tissues than H+ ions produced with lactate.

scholarly journals The Formation of Brine Drainage Features in Young Sea Ice

1975 ◽  
Vol 14 (70) ◽  
pp. 137-154 ◽  
Author(s):  
Lars Ingolf Eide ◽  
Seelye Martin
Keyword(s):  
Sea Ice ◽  
Laboratory Experiments ◽  
Sea Water ◽  
Salt Water ◽  
Pressure Head ◽  
Drainage Channels ◽  
The Difference ◽  
Thin Plastic ◽  
Ice Water ◽  
Brine Channel

Laboratory experiments on the growth of sea ice in a very thin plastic tank filled with salt water, cooled from above and insulated with thermopane, clearly show the formation and development of brine drainage channels. The sea-water freezing cell is 0.3 cm thick by 35 cm wide by 50 cm deep; the thermopane insulation permits the ice interior to be photographed. Experimentally, we observe that vertical channels with diameters of 1 to 3 mm and associated smaller feeder channels extend throughout the ice sheet. Close examination of the brine channels show that their diameter at the ice-water interface is much narrower than higher up in the ice, so that the channel has a “neck” at the interface. Further, oscillations occur in the brine channels, in that brine flows out of the channel followed by a flow of sea-water up into the channel. Theoretically, a qualitative theory based on the difference in pressure head between the brine inside the ice and the sea-water provides a consistent explanation for the formation of the channels, and the onset of a convective instability explains the existence of the neck. Finally, an analysis based on the presence of the brine-channel neck provides an explanation for the observed oscillations.

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