Histopathology of the disease causing mass mortality of sea urchins (Strongylocentrotus droebachiensis) in Nova Scotia

1985 ◽  
Vol 45 (3) ◽  
pp. 260-271 ◽  
Author(s):  
G.M. Jones ◽  
A.J. Hebda ◽  
R.E. Scheibling ◽  
R.J. Miller
Keyword(s):  
Nova Scotia ◽  
Sea Urchins ◽  
Mass Mortality ◽  
Strongylocentrotus Droebachiensis

Predation by Rock Crabs (Cancer irroratus) on Diseased Sea Urchins (Strongylocentrotus droebachiensis) in Nova Scotia

1984 ◽  
Vol 41 (12) ◽  
pp. 1847-1851 ◽  
Author(s):  
Robert E. Scheibling
Keyword(s):  
Nova Scotia ◽  
Sea Urchins ◽  
Mass Mortality ◽  
Strongylocentrotus Droebachiensis ◽  
Significant Preference ◽  
Laboratory Findings ◽  
Cancer Irroratus ◽  
Feeding Experiments ◽  
Defensive Behaviors ◽  
Strong Attachment

Predation of morbid sea urchins (Strongylocentrotus droebachiensis) by rock crabs (Cancer irroratus) and other predators was observed using SCUBA during an outbreak of disease in southwestern Nova Scotia in August 1983. Disease increases susceptibility of sea urchins to predation by precluding natural defensive behaviors including spine projection, strong attachment to the substratum, and aggregation. In laboratory feeding experiments, rock crabs preferred diseased or narcotized sea urchins over healthy ones and fed upon them at a much higher rate than crabs given only healthy sea urchins as prey. Rock crabs showed no significant preference between diseased and narcotized sea urchins. Rock crabs clearly preferred mussels over healthy or diseased sea urchins. Although rock crabs do not appear to be important predators of healthy sea urchins, from field and laboratory findings I conclude that they contribute to mass mortality of sea urchins by preying upon morbid individuals during outbreaks of disease.

scholarly journals Validating the identity of Paramoeba invadens, the causative agent of recurrent mass mortality of sea urchins in Nova Scotia, Canada

2013 ◽  
Vol 103 (3) ◽  
pp. 209-227 ◽  
Author(s):  
CJ Feehan ◽  
J Johnson-Mackinnon ◽  
RE Scheibling ◽  
JS Lauzon-Guay ◽  
AGB Simpson
Keyword(s):  
Nova Scotia ◽  
Causative Agent ◽  
Sea Urchins ◽  
Mass Mortality

Relationship Between Destructive Grazing by the Sea Urchin, Strongylocentrotus droebachiensis, and the Abundance of American Lobster, Homarus americanus, on the Atlantic Coast of Nova Scotia

1981 ◽  
Vol 38 (11) ◽  
pp. 1339-1349 ◽  
Author(s):  
W. G. Wharton ◽  
K. H. Mann
Keyword(s):  
Population Structure ◽  
Nova Scotia ◽  
Sea Urchins ◽  
Atlantic Coast ◽  
Homarus Americanus ◽  
Strongylocentrotus Droebachiensis ◽  
American Lobster ◽  
History Of ◽  
Kelp Bed ◽  
The Relationship

Relationships between percentage cover of macroalgae, population structure of sea urchins (Strongylocentrotus droebachiensis), and the history of the lobster fishery were examined at nine sites distributed along the Atlantic coast of Nova Scotia from Guysborough County in the northeast to Pubnico in the southwest. At Pubnico there was dense algal cover and a small number of urchins living in crevices, and at Cape Sable there was an area of transition, but at all other sites there were urchin-dominated barren grounds. When the population structure of the urchins was compared with that previously observed in St. Margaret's Bay before, during, and after destruction of beds of kelp (Laminaria spp. and Agarum) by overgrazing, it was concluded that kelp bed destruction occurred on the coast north of Halifax prior to 1970, and on the coast south of Halifax after 1970. From the records of American lobster (Homarus americanus) catches it was concluded that a critical decline in catches at each site occurred a few years after kelp bed destruction. Information from various sources is synthesized into a coherent theory of the relationship between lobsters, other predators, sea urchins, and kelp.Key words: lobsters, Homarus americanus; sea urchins, Strongylocentrotus droebachiensis; destructive grazing, kelp, Laminaria, Agarum

Repopulation of the shallow subtidal zone by green sea urchins (Strongylocentrotus droebachiensis) following mass mortality in Nova Scotia, Canada

2005 ◽  
Vol 85 (6) ◽  
pp. 1511-1517 ◽  
Author(s):  
Sheanna M. Brady ◽  
Robert E. Scheibling
Keyword(s):  
Sea Urchins ◽  
Disease Outbreak ◽  
Mass Mortality ◽  
Strongylocentrotus Droebachiensis ◽  
Subtidal Zone ◽  
Test Diameter ◽  
Lower Margin ◽  
Primary Means ◽  
Kelp Bed ◽  
Shallow Subtidal

Repopulation by green sea urchins Strongylocentrotus droebachiensis of a steeply sloping rock bottom was monitored at a wave-exposed headland (Chebucto Head) following a disease outbreak that caused mass mortality in September 1999. Density and size of urchins were sampled in four depth strata: at 8–10 m in an urchin grazing aggregation (front) along the lower margin of a kelp bed, at 12 m and 16 m on a bedrock ramp, and at 24 m on a cobble and boulder field where urchins were unaffected by the disease. Shoreward migration of adults along the ramp from the surviving population at 24 m was the primary means of repopulation, which was augmented by recruitment via planktonic larvae. At 16 m, urchin density stabilized (at ∼50 urchins m−2) within six months of the die-off while repopulation at 12 m took more than eight months. A grazing front of large urchins (40–60 mm, test diameter) had formed along the lower edge of a kelp bed by January 2002, which reached densities of up to 284 urchins m−2. Video surveys at Chebucto Head and two adjacent locations of similar bathymetry revealed an extensive urchin population between 25 and 55 m depth, with a mean density on rocky substrata of 73 urchins m−2.

scholarly journals Evidence for a trophic cascade on rocky reefs following sea star mass mortality in British Columbia

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1980 ◽  
Author(s):  
Jessica A. Schultz ◽  
Ryan N. Cloutier ◽  
Isabelle M. Côté
Keyword(s):  
British Columbia ◽  
Trophic Cascade ◽  
Sea Urchins ◽  
Fold Increase ◽  
Mass Mortality ◽  
Strongylocentrotus Droebachiensis ◽  
Population Declines ◽  
Sea Star ◽  
Sea Stars ◽  
Study Sites

Echinoderm population collapses, driven by disease outbreaks and climatic events, may be important drivers of population dynamics, ecological shifts and biodiversity. The northeast Pacific recently experienced a mass mortality of sea stars. In Howe Sound, British Columbia, the sunflower starPycnopodia helianthoides—a previously abundant predator of bottom-dwelling invertebrates—began to show signs of a wasting syndrome in early September 2013, and dense aggregations disappeared from many sites in a matter of weeks. Here, we assess changes in subtidal community composition by comparing the abundance of fish, invertebrates and macroalgae at 20 sites in Howe Sound before and after the 2013 sea star mortality to evaluate evidence for a trophic cascade. We observed changes in the abundance of several species after the sea star mortality, most notably a four-fold increase in the number of green sea urchins,Strongylocentrotus droebachiensis, and a significant decline in kelp cover, which are together consistent with a trophic cascade. Qualitative data on the abundance of sunflower stars and green urchins from a citizen science database show that the patterns of echinoderm abundance detected at our study sites reflected wider local trends. The trophic cascade evident at the scale of Howe Sound was observed at half of the study sites. It remains unclear whether the urchin response was triggered directly, via a reduction in urchin mortality, or indirectly, via a shift in urchin distribution into areas previously occupied by the predatory sea stars. Understanding the ecological implications of sudden and extreme population declines may further elucidate the role of echinoderms in temperate seas, and provide insight into the resilience of marine ecosystems to biological disturbances.

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