Sea Otters, Sea Urchins, and Kelp Beds: Some Questions of Scale

1988 ◽  
pp. 116-150 ◽  
Author(s):  
J. A. Estes ◽  
C. Harrold
Keyword(s):  
Sea Urchins ◽  
Sea Otters ◽  
Kelp Beds

Kelp Beds and Sea Otters: An Experimental Approach

Ecology ◽  
1980 ◽  
Vol 61 (3) ◽  
pp. 447-453 ◽  
Author(s):  
David O. Duggins
Keyword(s):  
Experimental Approach ◽  
Sea Otters ◽  
Kelp Beds

The dynamics of destructive grazing of kelp beds by sea urchins in Nova Scotia

2020 ◽  
pp. 871-871
Author(s):  
R. E. Scheibling ◽  
A. W. Hennigar ◽  
T. Balch
Keyword(s):  
Nova Scotia ◽  
Sea Urchins ◽  
Kelp Beds

Geographic and environmental factors affecting the distribution of kelp beds and barren grounds and changes in biota associated with kelp reduction at sites along the Norwegian coast

1997 ◽  
Vol 54 (12) ◽  
pp. 2872-2887 ◽  
Author(s):  
Knut Sivertsen
Keyword(s):  
Environmental Factors ◽  
Sea Urchins ◽  
Strongylocentrotus Droebachiensis ◽  
The Arctic ◽  
Laminaria Hyperborea ◽  
Factors Affecting ◽  
Kelp Beds ◽  
The Mean ◽  
Transition Areas ◽  
Barren Grounds

Sites at 244 locations along the west and north Norwegian coasts were investigated to evaluate whether kelp (Laminaria hyperborea) beds had been overgrazed by the sea urchins Strongylocentrotus droebachiensis and Echinus esculentus in the years 1981-1992. Barren ground communities were found in sheltered and moderately wave-exposed areas mainly in the inner and middle archipelago from Nordmøre (63°N) northwards. Densities of large-sized (adult and intermediate) L. hyperborea were 20.7 individuals ·m-2 in kelp beds and 9.7 individuals ·m-2 in transition areas. Juvenile Laminaria spp. were present at densities of 23.9 individuals ·m-2 in kelp beds, 3.6 individuals ·m-2 in transition areas, 0.0 individuals ·m-2 in barren grounds, and 59.1 individuals ·m-2 in kelp-harvested locations. Both the densities and the mean size of S. droebachiensis in barren grounds decreased northwards. The mean densities were 52.2 and 26.1 individuals ·m-2 for the areas south and north of the Arctic Circle, respectively. Multivariate analysis (CANOCO) showed that seven ``environmental'' factors (i.e., kelp depth gradient, distance (latitude), time of sampling, nematode infection in S. droebachiensis, wave exposure, coastal gradient, and substratum) contributed significantly to variability in the distribution of kelp beds and barren grounds. Species in hard-bottom communities in shallow waters could be divided into three distinct BIOTA.

Destructive Grazing of Kelp by Sea Urchins in Eastern Canada

1976 ◽  
Vol 33 (6) ◽  
pp. 1278-1283 ◽  
Author(s):  
P. A. Breen ◽  
K. H. Mann
Keyword(s):  
Nova Scotia ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Large Contribution ◽  
Eastern Canada ◽  
Kelp Beds ◽  
Urchin Grazing

Destruction of kelp beds by sea urchins has been documented in St. Margaret’s Bay, Nova Scotia, and also appears to be taking place in other parts of eastern Canada. Continued sea urchin settlement onto grazed areas prevents the return of kelp and other algae for long periods. Because of the large contribution of kelp beds to coastal productivity, the disappearance of kelp from large areas is alarming. Dynamics of sea urchin grazing are discussed.

Abalones and sea urchins in an area inhabited by sea otters

1973 ◽  
Vol 23 (3) ◽  
pp. 213-219 ◽  
Author(s):  
L. F. Lowry ◽  
J. S. Pearse
Keyword(s):  
Sea Urchins ◽  
Sea Otters

The Relation Between Lobster Abundance, Sea Urchins, and Kelp Beds

1972 ◽  
Vol 29 (5) ◽  
pp. 603-605 ◽  
Author(s):  
K. H. Mann ◽  
P. A. Breen
Keyword(s):  
Sea Urchin ◽  
Food Supply ◽  
Sea Urchins ◽  
Critical Density ◽  
Eastern Canada ◽  
Kelp Beds ◽  
Key Species

When subtidal communities are disturbed and sea urchin populations expand, they frequently overgraze their food supply, eliminating large seaweeds from considerable areas. The hypothesis is advanced that the lobster is a key species, controlling sea urchin populations in eastern Canada, and that reduction of lobster populations below a critical density has led to overgrazing of seaweeds in many places.

Aquacultural Techniques for Creating and Restoring Beds of Giant Kelp, Macrocystis spp.

1976 ◽  
Vol 33 (4) ◽  
pp. 1015-1023 ◽  
Author(s):  
Wheeler J. North
Keyword(s):  
Baja California ◽  
Sea Urchins ◽  
Food Additives ◽  
Stable Population ◽  
Giant Kelp ◽  
Herbivorous Fishes ◽  
Kelp Beds ◽  
Mass Cultures ◽  
Kelp Bed ◽  
Reproductive Processes

Giant kelp (Macrocystis spp.) occurs as extensive beds along the coasts of Baja California and California. The kelp beds form desirable habitat for fishes and invertebrates. The kelp plants are harvested and processed to produce food additives and chemicals. Many Califorman kelp beds have dwindled or disappeared since 1940. We have developed a number of aquacultural techniques to reverse trends of deterioration. One important cause of kelp bed damage can arise from grazing by sea urchins or herbivorous fishes. Urchins can be controlled by quicklime or by crushing the animals with hammers. Fishes can be controlled by netting. In areas where kelp is sparse or has disappeared, stands can be recreated by transplantation techniques. Where reproductive processes are not adequate to maintain a stable population, mass cultures of microscopic gametophytes and sporophytes can be introduced.

scholarly journals Harlequin Ducks (Histrionicus histrionicus) Scavenge Sea Urchin Fragments from Foraging Sea Otters (Enhydra lutris)

2016 ◽  
Vol 130 (2) ◽  
pp. 91 ◽  
Author(s):  
Erin Rechsteiner ◽  
Angeleen Olson
Keyword(s):  
Red Sea ◽  
Sea Urchins ◽  
Keystone Species ◽  
Sea Otter ◽  
Enhydra Lutris ◽  
Sea Otters ◽  
Important Prey ◽  
Histrionicus Histrionicus ◽  
Harlequin Ducks

Foraging animals may risk association with potential predators to obtain otherwise inaccessible prey. We observed this strategy in wintering Harlequin Ducks (Histrionicus histrionicus) scavenging fragments of Red Sea Urchins (Mesocentrotus franciscanus) from foraging Sea Otters (Enhydra lutris) that were re-occupying an area from which they had been ecologically absent since about 1850. Harlequin Ducks, like other sea ducks, have not previously been reported scavenging from other birds or mammals. In British columbia, Red Sea Urchins have reached large sizes and densities since the removal of Sea Otter predators by the marine fur trade in the 18th and 19th centuries. Observations of Sea Otters and Harlequin Ducks were made in 4 areas, spanning a time gradient of Sea Otter occupation from 1 to 5 years. During 3 months of observations (December 2013 – February 2014), Harlequin Ducks were associated with foraging Sea Otters only at sites that were recently occupied by Sea Otters (≤ 2 months), where the proportion of urchins in Sea Otter diets was highest and where the ducks acquired urchin fragments from foraging Sea Otters. We suggest that Sea Otters re-occupying their historic range and consuming predominantly large Red Sea Urchins provide a temporarily available prey subsidy for Harlequin Ducks. Our observations document a novel effect of Sea Otters providing important prey supplementation to a marine bird when foraging in urchin-rich habitats, contributing to the overall role of Sea Otters as a keystone species.

Kelp forests, sea urchins, sea otters, and sewage pollution

1988 ◽  
Vol 19 (6) ◽  
pp. 244-246 ◽  
Author(s):  
Michael Waldichuk
Keyword(s):  
Sea Urchins ◽  
Kelp Forests ◽  
Sewage Pollution ◽  
Sea Otters
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