scholarly journals Size, growth, and density data for shallow-water sea urchins from Mexico to the Aleutian Islands, Alaska, 1956-2016

Ecology ◽  
2018 ◽  
Vol 99 (3) ◽  
pp. 761-761 ◽  
Author(s):  
Thomas A. Ebert ◽  
Louis M. Barr ◽  
James L. Bodkin ◽  
Dirk Burcham ◽  
Dominique Bureau ◽  
...  
Keyword(s):  
Shallow Water ◽  
Sea Urchins ◽  
Aleutian Islands ◽  
Density Data ◽  
Size Growth

Suspension freezing of bottom sediment and biota in the Northwest Passage and implications for Arctic Ocean sedimentation

1992 ◽  
Vol 29 (4) ◽  
pp. 693-703 ◽  
Author(s):  
Erk Reimnitz ◽  
Louie Marincovich Jr. ◽  
Michael McCormick ◽  
W. M. Briggs
Keyword(s):  
Arctic Ocean ◽  
Shallow Water ◽  
Sea Urchins ◽  
The Arctic ◽  
River Flooding ◽  
Northwest Passage ◽  
Beaufort Gyre ◽  
Transpolar Drift ◽  
Living Organisms ◽  
Northern Alaska

Ice observations and sediment collected in a summer transit through the Northwest Passage provide insights on suspension freezing, the most important sediment entrainment mechanism for the Arctic Ocean. No evidence was seen for entrainment by bottom adfreezing, bluff slumping, river flooding, dragging ice keels, or significant eolian transport from land to sea. Lack of eolian sediment loading in the Northwest Passage, together with that already reported for northern Alaska, eliminates wind as an important source for fine sediment in the pack of the Beaufort Gyre and related parts of the Transpolar Drift. Muddy sediment with pebbles and cobbles, algae with holdfasts, ostracodes with appendages, and well-preserved mollusks and sea urchins were collected from two sites in a 50 km long stretch of turbid ice. These materials indicate that suspension freezing reaching to a water depth of 25–30 m during the previous fall was responsible for entrainment. This mechanism requires rapid ice formation in open, shallow water during a freezing storm, when the ocean becomes supercooled, and frazil and anchor ice attach to and ultimately lift sediment and living organisms to the sea surface. The mechanism, already known to be important in the Beaufort Sea, probably also affects wide, shallow Siberian shelves and leads to cross-shelf transport of shallow-water organisms and dropstones with "glacial striations" toward deep basins. This makes distinguishing glacial–interglacial cycles more difficult.

Habitat selection by common eiders in winter and its interaction with flock size

1993 ◽  
Vol 71 (6) ◽  
pp. 1259-1266 ◽  
Author(s):  
Magella Guillemette ◽  
John H. Himmelman ◽  
Cyrille Barette ◽  
Austin Reed
Keyword(s):  
Habitat Selection ◽  
Shallow Water ◽  
Prey Density ◽  
Sea Urchins ◽  
Day Length ◽  
Antipredator Behaviour ◽  
Somateria Mollissima ◽  
Flock Size ◽  
Eastern Canada ◽  
Diving Depth

We studied habitat selection in relation to prey density and water depth in the common eider, Somateria mollissima L., wintering in the Gulf of St. Lawrence, eastern Canada. In this region, eiders are confronted with low temperatures, ice cover, and reduced day length. We predicted that they should select feeding habitats characterized by high prey density and shallow water to minimize the time and energy spent while diving. About 1000 flocks were localized by triangulation on our study site (20.5 km2). We inferred the diving depth and the habitat being used from the position of eiders on bathymetric and community maps. The highest density of prey occurred in shallow water reefs where there were patches of blue mussels, Mytilus edulis L., and green sea urchins, Strongylocentrotus droebachienensis (Müller). Despite the fact that eiders can dive to depths as great as 42 m to feed, they strongly aggregate in shallow water, and their distribution closely coincides with the highest density of prey. The degree of selection for the reef habitat varies with seasonal variations in the size of flocks and in the total number of eiders present. Although flocking as an antipredator behaviour cannot be rejected, we interpret the high degree of flocking by eiders in our study area as a strategy to facilitate feeding in winter.

scholarly journals The Roles of Spinochromes in Four Shallow Water Tropical Sea Urchins and Their Potential as Bioactive Pharmacological Agents

Marine Drugs ◽  
2017 ◽  
Vol 15 (6) ◽  
pp. 179 ◽  
Author(s):  
Lola Brasseur ◽  
Elise Hennebert ◽  
Laurence Fievez ◽  
Guillaume Caulier ◽  
Fabrice Bureau ◽  
...  
Keyword(s):  
Shallow Water ◽  
Sea Urchins ◽  
Pharmacological Agents ◽  
Tropical Sea

Sea Urchins in the Saint Lawrence Estuary: Their Abundance, Size-Structure, and Suitability for Commercial Exploitation

1983 ◽  
Vol 40 (4) ◽  
pp. 474-486 ◽  
Author(s):  
John H. Himmelman ◽  
Yves Lavergne ◽  
Fritz Axelsen ◽  
André Cardinal ◽  
Edwin Bourget
Keyword(s):  
Growth Rate ◽  
Shallow Water ◽  
Sea Urchin ◽  
Size Structure ◽  
Sea Urchins ◽  
Strongylocentrotus Droebachiensis ◽  
Lawrence Estuary ◽  
Algal Abundance ◽  
Ice Conditions ◽  
Intermediate Size

Quantitative transects were made at nine locations along the Saint Lawrence Estuary, Québec, to examine changes in the abundance and size-structure of populations of the green sea urchin, Strongylocentrotus droebachiensis, in relation to the estuarine gradient. Near the seaward extremity of the estuary, sea urchin densities are very high and small urchins are particularly abundant in shallow water. In contrast, midway up the estuary, small urchins are scarce in shallow water, probably because they cannot tolerate the periodic drops in surface salinities which occur there. Where urchin densities are high, urchin grazing severely limits algal production, and because of low algal food availability, the urchin growth rate is exceedingly low. In the Upper Estuary, urchin numbers are low and no urchins are found near the surface. There is feeble recruitment of urchins, and the near absence of urchins of intermediate size suggests that there is a high probability that juveniles are killed before they reach intermediate size. The urchin growth rate is accelerated because of the abundance of algae present, and below 10 m deep some juveniles survive through the intermediate size range. After they reach 40–50 mm in diameter, they can move up to the 2- to 10-m-depth zone and can tolerate the periods of hypo-osmotic conditions which occur there. Suitable populations for commercial use are most likely found where salinity or winter ice conditions reduce urchin numbers to a level permitting greater algal abundance and an elevated somatic and gonadal growth of the remaining urchins.

scholarly journals Distribution of sea urchins living near shallow water CO2 vents is dependent upon species acid–base and ion-regulatory abilities

2013 ◽  
Vol 73 (2) ◽  
pp. 470-484 ◽  
Author(s):  
P. Calosi ◽  
S.P.S. Rastrick ◽  
M. Graziano ◽  
S.C. Thomas ◽  
C. Baggini ◽  
...  
Keyword(s):  
Shallow Water ◽  
Sea Urchins ◽  
Acid Base

A new genus and thirteen new species of sea stars (Asteroidea: Echinasteridae) from the Aleutian Island Archipelago

Zootaxa ◽  
2010 ◽  
Vol 2571 (1) ◽  
pp. 1 ◽  
Author(s):  
ROGER N. CLARK ◽  
STEPHEN C. JEWETT
Keyword(s):  
New Species ◽  
Shallow Water ◽  
Type Species ◽  
New Genus ◽  
Aleutian Islands ◽  
Aleutian Island ◽  
Sea Stars

A new genus and thirteen new species of echinasterid sea stars are described from nearshore waters of the Aleutian Islands. The new genus Aleutihenricia is distinguished from Henricia by the morphology and arrangement of the skeletal ossicles. Henricia beringiana D'yakonov, 1950 is designated as the type species. The new species described include Aleutihenricia federi, Henricia lineata, H. uluudax, H. iodinea, H. rhytisma, H. gemma, H. echinata, H. vermilion, H. elachys, H. insignis, Odontohenricia aurantia, O. ahearnae, and O. violacea. In addition to the descriptions, associations between echinasterids and sponges are briefly discussed. A key to the shallow water (<20 m) Echinasteridae of the Aleutian Islands is provided.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Fate of sperm membrane in fertilized ova

1993 ◽  
Vol 51 ◽  
pp. 40-41
Author(s):  
Frank J. Longo
Keyword(s):  
Electron Microscopy ◽  
Electrical Activity ◽  
Sea Urchins ◽  
Morphological Changes ◽  
Integrated System ◽  
Electrophysiological Recording ◽  
Experimental Conditions ◽  
The Status ◽  
Sperm Membrane ◽  
Temporal And Spatial

Measurement of the egg's electrical activity, the fertilization potential or the activation current (in voltage clamped eggs), provides a means of detecting the earliest perceivable response of the egg to the fertilizing sperm. By using the electrical physiological record as a “real time” indicator of the instant of electrical continuity between the gametes, eggs can be inseminated with sperm at lower, more physiological densities, thereby assuring that only one sperm interacts with the egg. Integrating techniques of intracellular electrophysiological recording, video-imaging, and electron microscopy, we are able to identify the fertilizing sperm precisely and correlate the status of gamete organelles with the first indication (fertilization potential/activation current) of the egg's response to the attached sperm. Hence, this integrated system provides improved temporal and spatial resolution of morphological changes at the site of gamete interaction, under a variety of experimental conditions. Using these integrated techniques, we have investigated when sperm-egg plasma membrane fusion occurs in sea urchins with respect to the onset of the egg's change in electrical activity.

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