next message in archive
next message in thread
previous message in archive
Index of Subjects
--Apple-Mail-19-938280807 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Hi Gayle, Th green crab (Carcinus maenas), originally a Palearctic (old world) species, was first detected in North America in 1817. It is now globally dispersed, occurring in Australia, Hawaii, Sri Lanka, South Africa, along the Atlantic and Pacific coasts of North America, and the Atlantic coast of South America. In eastern North America it is now found from Nova Scotia south to Virginia. On the Pacific coast it was first found in San Francisco in 1989 and now occurs from California north to British Columbia. The green crab has had a negative impact on soft-shell clams, young oysters, and native crabs in the northeast since the 1950s. There have been significant impacts to commercial fisheries and natural ecosystems. Green crabs have been implicated in the destruction of the soft-shell clam (Mya arenaria) fisheries in New England and the reduction of populations of other commercially important bivalves including the scallop (Argopecten irradians) and the northern quahog (Mercenaria mercenaria). In Connecticut, weekly rates of crab predation on scallops were as high as 70% leading researchers) to conclude that green crabs were responsible for most observed mortality in scallops and that the green crab was "one of the worst, if not the worst, calm predators we know." Lafferty and Kuris (1996) estimated commercial fishery losses in the United States resulting from green crab predation at $44 million dollars. Green crabs eat a wide variety of prey and can significantly reduce populations of native clams and crabs in areas where they have become established. Their ability to out-compete native species for food resources, high reproductive capacity, and wide environmental tolerances lend them the capacity to fundamentally alter community structure in coastal ecosystems. For more information about this species see the USGS page at: http://nas.er.usgs.gov/queries/FactSheet.asp?SpeciesID=190 Where there are references and links to many other sources of information as well. All the best! Chris On 8-Oct-07, at 8:56 AM, Gayle MacLean wrote: > Hello Bernard, > > Beside one of the photos of the Green Crab (River Bourgeois, Cape > Breton), you have in brackets, "alien species". Was that because of > it's posturing stance or because it has been introduced and not > native to the area, and if so, would it be considered a pest? > > Thanks, > > Gayle MacLean, Dartmouth > PS: Beautiful photographs, BTW, as are all of the pictures that are > posted by the members of this group!! > > Bernard Burke <blburke@ns.sympatico.ca> wrote: > Hi all > > Here are some updated photos to the site with a few mixed in from > my sister Rita and her husband, and one by Murray Newell of the > Solitary Sandpiper he mentioned in his posting. This new group of > photos starts with a Wren and ends with a Spruce Grouse (from # 63 > to # 73). Here is the first one: > > http://bernieb.smugmug.com/gallery/916397/4/46469808/Medium > > Cheers > > Bernard Burke > blburke@ns.sympatico.ca > Dartmouth > > > Be smarter than spam. See how smart SpamGuard is at giving junk > email the boot with the All-new Yahoo! Mail _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. _. Christopher Majka - Nova Scotia Museum of Natural History 1747 Summer Street, Halifax, Nova Scotia, Canada B3H 3A6 (902) 424-6435 Email <c.majka@ns.sympatico.ca> _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. _. --Apple-Mail-19-938280807 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1 <html><body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; = -webkit-line-break: after-white-space; "> Hi Gayle,<div><br class=3D"webkit-block-placeholder"></div><div>Th green = crab (<i>Carcinus=A0maenas</i>), originally a Palearctic (old world) = species, was first detected in North America in 1817. It is now globally = dispersed, occurring in=A0Australia, Hawaii, Sri Lanka, South Africa, = along the Atlantic and Pacific coasts of North America, and the Atlantic = coast of South America. In eastern North America it is now found from = Nova Scotia south to Virginia. On the Pacific coast it was first found = in San Francisco in 1989 and now occurs from California north to British = Columbia.=A0</div><div><p>The green crab has had a negative impact on = soft-shell clams, young oysters, and native crabs in the northeast since = the 1950s. There have been significant impacts to commercial fisheries = and natural ecosystems.=A0 Green crabs have been implicated in the = destruction of the soft-shell clam (<i>Mya arenaria</i>) fisheries in = New England and the reduction of populations of other commercially = important bivalves including the scallop (<i>Argopecten irradians</i>) = and the northern quahog (<i>Mercenaria mercenaria</i>).=A0 In = Connecticut, weekly rates of crab predation on scallops were as high as = 70% leading researchers) to conclude that green crabs were responsible = for most observed mortality in scallops and that the green crab was "one = of the worst, if not the worst, calm predators we know."</p><p>Lafferty = and Kuris (1996) estimated commercial fishery losses in the United = States resulting from green crab predation at $44 million dollars. Green = crabs eat a wide variety of prey and can significantly reduce = populations of native clams and crabs in areas where they have become = established.=A0 Their ability to out-compete native species for food = resources, high reproductive capacity,=A0 and wide environmental = tolerances lend them the capacity to fundamentally alter community = structure in coastal ecosystems.</p><p>For more information about this = species see the USGS page at:</p><p><a = href=3D"http://nas.er.usgs.gov/queries/FactSheet.asp?SpeciesID=3D190">http= ://nas.er.usgs.gov/queries/FactSheet.asp?SpeciesID=3D190</a></p><p>Where = there are references and links to many other sources of information as = well.</p><p>All the best!</p><p>Chris</p> </div> <div><br> <div><div>On = 8-Oct-07, at 8:56 AM, Gayle MacLean wrote:</div><br = class=3D"Apple-interchange-newline"><blockquote type=3D"cite"><span = class=3D"Apple-style-span" style=3D"border-collapse: separate; color: = rgb(0, 0, 0); font-family: 'Times New Roman'; font-size: 12px; = font-style: normal; font-variant: normal; font-weight: normal; = letter-spacing: normal; line-height: normal; orphans: 2; text-align: = auto; text-indent: 0px; text-transform: none; white-space: normal; = widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; = -webkit-border-vertical-spacing: 0px; = -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: = auto; -webkit