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

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.

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.

Application of Antibiotics in the Cultivation of Dungeness Crab, Cancer Magister

1978 ◽  
Vol 35 (10) ◽  
pp. 1343-1349 ◽  
Author(s):  
William S. Fisher ◽  
Richard T. Nelson
Keyword(s):  
Key Words ◽  
Antibiotic Treatment ◽  
Treatment Effectiveness ◽  
Artemia Salina ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
Low Concentrations ◽  
Periodic Treatment ◽  
Static Cultivation ◽  
Apparent Age

In static cultivation of Cancer magister zoeae, duration of antibiotic treatment, effectiveness of various antibiotics, and therapeutic pretreatment of the live food were evaluated. Periodic treatment with antibiotics was necessary to maintain high zoeal survival, the greatest benefit occurring during the early zoeal period. Low concentrations (1–10 mg/L) of chloramphenicol were equally or more successful than 100 mg/L streptomycin plus 100 mg/L penicillin. Kanamycin (100 mg/L) and neomycin (50 mg/L) appeared toxic to the zoeae. Successful antibiotic treatment did not alter the development and increased the weight of cultivated zoeae, although these were all lighter than captured crabs of the same apparent age. There was indication that elimination of bacterial epibionts with antibiotics restricted the attachment of other microbial epibionts. Key words: aquaculture, mariculture, epibionts, Crustacea epibionts, zoeal survival, Artemia salina, antibiotics

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

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.

Premating and Mating Behavior of the Dungeness Crab (Cancer magister Dana)

1966 ◽  
Vol 23 (9) ◽  
pp. 1319-1323 ◽  
Author(s):  
C. Dale Snow ◽  
John R. Neilsen
Keyword(s):  
Mating Behavior ◽  
Dungeness Crab ◽  
Continuous Observation ◽  
Cancer Magister ◽  
Male And Female ◽  
Male Crab

A male and female Dungeness crab (Cancer magister Dana) were kept under continuous observation in an aquarium to observe the premating embrace, female ecdysis, and mating. The male held the female in premating embrace from June 10 until June 18, 1965, when she molted. The male allowed the female to reverse her position from the premating embrace, sternum to sternum, to that of female carapace to male sternum only after she became aggressive. The male never allowed the female to escape from his control while she molted. Copulation occurred 1 hr and 32 min after female ecdysis, when the new exoskeleton had firmed somewhat, and the male carried the female in a postmating embrace for 2 days.Extensive wear on the chelipeds of male crabs may reflect prolonged periods in the premating embrace and stroking of the female by the male rather than matings with several females. The male crab probably becomes aware of the female's readiness to molt by her aggressive pinching of maxillae and eyestalks.

Effort Dynamics of the Northern California Dungeness Crab (Cancer magister) Fishery

1983 ◽  
Vol 40 (3) ◽  
pp. 337-346 ◽  
Author(s):  
Louis W. Botsford ◽  
Richard D. Methot Jr. ◽  
Warren E. Johnston
Keyword(s):  
Population Dynamics ◽  
Time Lag ◽  
Substantial Effect ◽  
Fishing Effort ◽  
Northern California ◽  
Dungeness Crab ◽  
Cancer Magister ◽  
Harvest Rate ◽  
Predator Prey ◽  
Market Expansion

Knowledge of the dynamic response of fishing effort to abundance is essential to a complete understanding of the cycles in catch in the northern California Dungeness crab fishery. In this fishery there is a lagged response of harvest rate to changes in abundance that is caused either by a time lag in fishermen entering and leaving the fishery following changes in abundance, a lag in market expansion and contraction following changes in abundance, or a combination of both. The time lag in this response appears to have decreased over the past 30 yr. This lagged response is a potential cause of the cycles. However, neither of the two potential cyclic mechanisms examined here, a predator–prey mechanism (with man as the predator) and a price-dependent escapement mechanism (with price dependent on past catch), is a cause of these cycles. Although time-varying effort does not cause the cycles, it does have a substantial effect on the resulting catch record and population dynamics. If there is a density-dependent recruitment mechanism in this population as proposed earlier, the presence of this lagged response would cause the period of observed cycles to be longer than would be expected on the basis of population dynamics alone. Hence, previous estimates of the expected period of cycles from various population mechanisms are low. Removal of this response is a potential means of stabilizing this fishery.Key words: effort, Dungeness crab, harvest rate, predator–prey, price, stability, age, cycles

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