scholarly journals Horizontal distributions of Dungeness crab (Cancer magister) and red rock crab (Cancer productus) larvae in the Strait of Georgia, British Columbia

2014 ◽  
Vol 71 (9) ◽  
pp. 2564-2577 ◽  
Author(s):  
Kevin A. Sorochan ◽  
Pedro A. Quijón
Keyword(s):  
Horizontal Distribution ◽  
Spatial And Temporal Variability ◽  
Dungeness Crab ◽  
Physical Processes ◽  
Cancer Magister ◽  
Strait Of Georgia ◽  
Water Properties ◽  
Larval Stages ◽  
Cancer Productus ◽  
Rock Crab

Abstract The supply of planktonic larvae to adult populations is an important contributor to the spatial and temporal variability of benthic marine organisms. The ability to predict spatial patterns of larvae and recruits from the physical and biological processes that facilitate dispersal is required in order to advise and evaluate conservation and fisheries management decisions. In the present study, the horizontal distribution of Dungeness crab (Cancer magister) and red rock crab (Cancer productus) zoeae was described from surveys conducted in the Strait of Georgia in the spring of 2009 and 2010. Processes that may be responsible for generating spatial variability of larvae were evaluated based on (i) horizontal overlap between larvae and water properties, (ii) spatial dependence of larvae and water properties, and (iii) changes in the dispersion of stage-specific distributions. Interspecific variability between horizontal patterns of the first and second larval stages was primarily attributed to differences in the distribution of larval release locations, which appeared to be restricted to the southern and central strait for C. magister. Potential effects of physical processes on larval distributions are also discussed.

Wind-Induced Advection of Larval Decapods into Baie de Plaisance (Îles de la Madeleine, Québec)

1993 ◽  
Vol 50 (7) ◽  
pp. 1422-1434 ◽  
Author(s):  
Christiane Hudon ◽  
Pierre Fradette
Keyword(s):  
Spatial Association ◽  
Homarus Americanus ◽  
Horizontal Distribution ◽  
Climatic Conditions ◽  
Larval Abundance ◽  
Larval Stages ◽  
Early Stages ◽  
The North ◽  
Rock Crab ◽  
Wind Events

Abundance and spatial distribution of the larvae of the American lobster (Homarus americanus), the common rock crab (Cancer irroratus), and the toad crab (Hyas spp.), were monitored weekly during the summer of 1980 at a grid of 12 stations located in Baie de Plaisance. Following a period of winds ≥ 30 km∙h−1 shifting from the north to the southeast, large numbers of late-stage larvae of the three species were advected in the bay, concurrently with an intrusion of low-salinity water. Weekly abundances of consecutive larval stages were highly correlated, indicating that larvae tended to remain in the same water mass. Spatial association tended to be highest among the early stages within each species. The late larval stages of both lobster and rock crab behaved differently from the early stages with respect to light intensity and their horizontal distribution. Although the advection of water masses under the influence of wind events determines the overall abundance of larval decapods in Baie de Plaisance, larval behaviour (vertical migration and swimming ability) also affected distribution of older stage larvae but at a smaller scale. The dependence of advection on sporadic wind events occurring at the time of peak larval abundance reduces the chances of modelling yearly recruitment using average summer climatic conditions.

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.

Megalopal Spatial Distribution and Stock Separation in Dungeness Crab (Cancer magister)

1993 ◽  
Vol 50 (2) ◽  
pp. 416-429 ◽  
Author(s):  
G. S. Jamieson ◽  
A. Phillips
Keyword(s):  
Dungeness Crab ◽  
Cancer Magister ◽  
Strait Of Georgia ◽  
Daily Movement ◽  
The Pacific ◽  
Juan De Fuca ◽  
The Pacific Ocean ◽  
Estuarine Flow ◽  
Juan De Fuca Strait ◽  
Outer Coast

During the day, Dungeness crab (Cancer magister) megalopae from off the outer coasts of Vancouver Island and Washington are aggregated at about 25 m whereas those from the Strait of Georgia are at about 160 m. At night, both populations of megalopae seem to be mostly in the top metre of water. Juan de Fuca Strait, which connects the Strait of Georgia to the Pacific Ocean, typically has an estuarine circulation, with outflow in the top 50–100 m and deeper inflow. Because the daylight to dark ratio when megalopae are present is about 3:1, the Strait of Georgia and outer-coast megalopae are mostly retained within their own systems by currents at their daytime depths. Occasional intrusions of outer-coast megalopae into Juan de Fuca Strait may occur when estuarine flow in the Strait temporarily breaks down following sustained, strong, southwesterly winds; such intrusions are typically restricted to the south and head of Juan de Fuca Strait, and even extensive ones do not carry megalopae far into the Strait of Georgia. The daily movement of larval crab to cold (<10 °C), deep water in the Strait of Georgia may explain, at least partially, the delay in seasonal timing of settlement and their smaller physical size at settlement compared with outer-coast megalopae.

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.

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.

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