next message in archive
no next message in thread
previous message in archive
previous message in thread
Index of Subjects
>>>> Horseshoe crabs have appeared, several times in the last several decades, although it is not clear as to how often they were (accidentally) introduced. We have a couple of records where they probably made it up on their own, but the latest report from Shelburne Harbour, several years ago ( I think) appears to have been an illicit dump. DFO should have a report on the occurrence. Andrew >>> "Elizabeth Doull" <edoull@ns.sympatico.ca> 2/14/2008 2:10:03 pm >>> I recall seeing some horseshoe crabs here in Nova Scotia when I was a kid. I haven't seen one for years so are they extinct or not in this province? Thanks Liz ----- Original Message ----- From: "Roland McCormick" <roland.mccormick@ns.sympatico.ca> To: <naturens@chebucto.ns.ca> Sent: Thursday, February 14, 2008 1:41 PM Subject: Re: [NatureNS] Why save the Red Knot? - vertebrate hegemony? >I read in the paper recently that one of the boys I taught in school was >fined a couple of thousand dollars for using crabs as bait to catch >lobster. I wondered about that at the time because I had never heard about >using them for bait before, or the reason for the fine. I assume that is >what we are talking about here, and that there is a good reason for it. I >can assure you that if this is true the fines are a good deal more than >$25. > > Roland. > ----- Original Message ----- > From: "Paul S. Boyer" <psboyer@eastlink.ca> > To: <naturens@chebucto.ns.ca> > Sent: Thursday, February 14, 2008 11:26 AM > Subject: Re: [NatureNS] Why save the Red Knot? - vertebrate hegemony? > > >> The horseshoe crab is a living fossil, virtually unchanged since the >> Jurassic Period (in the middle of the Age of Reptiles). Tracks of >> spawning horseshoe crabs have been found in Devonian rocks of >> Pennsylvania, which are far, far older. Fossil relatives are found in >> Manitoba from the Ordovician Period, about 445 MY old. >> >> There are only a few species of horseshoe crabs in the world (the >> American one, the subject of the program, and three minor Asian >> species). The American horseshoe crab is the largest and the most >> numerous, and the most spectacular to watch. New Jersey is the center >> for their abundance and average size, or at least it used to be. >> >> It is not the medical use that threatens the population, but the >> wasteful and (IMHO) lunatic use of horseshoe crabs as bait, or even >> fertilizer. I have not checked recently, but when last I looked an >> annual license to take unlimited numbers of horseshoe crabs (seized from >> the beaches while they are trying to spawn) was a mere $25. Horseshoe >> crabs have a long lifespan, and do not recover quickly from the >> depredation of being hauled away in truckloads. Actually, the Red Knot >> probably can increase its numbers faster with environmental change than >> can the horseshoe crab, because the generation time is shorter for the >> Knots. >> >> On 14 Feb 2008, at 2:04 AM, Stephen Shaw wrote: >> >>> Unfortunately missed the program, but I had a mild comment on the >>> species-ist >>> emphasis here (sent it earlier but it didn't do through). >>> >>> Nothing against the Red Knot and of course I hope it survives, but the >>> received >>> vertebratocentric perspective on this is interesting. As the blurb >>> below >>> states, >>> there are lots of other similar peep species around, but the horseshoe >>> "crab" >>> Limulus polyphemus is a unique species here and has been practically >>> wiped out >>> in many of its former habitats on the US East coast, according to Bob >>> Barlow, a >>> former student of Hartline (see below) who still works on it, latterly >>> on its >>> visual behaviour under water. Apparently the market for its blood is >>> the main >>> reason for the punitive "harvesting". >>> >>> Besides having a far more interesting, ancient lineage, Limulus has >>> contributed to several outstanding scientific discoveries in vision >>> science, >>> notably that of "lateral inhibition" by which the nervous system >>> sharpens up >>> percepts, enhancing edge-detection in images. This has emerged as a >>> common enhancing operation elsewhere in nervous systems, but originally >>> came >>> mainly out of work on the compound eyes of Limulus in the 40s-60s -- >>> netting a >>> Nobel prize for H.K. Hartline, of the then Rockefeller Inst (now Univ). >>> In the >>> 60s, S. Yeandle made the first recordings of single photon captures in >>> the same >>> eye (since then recorded in vertebrates, though not in Red Knots), >>> while in the >>> 70's, the first detailed analyses of how photoreceptor currents work >>> (semi-universal) came out of measurements on huge photoreceptor cells >>> in the >>> ventral nerve that had been thought before this to be an olfactory >>> structure >>> (analysed since in vertebrates, though not in Red Knots). Circadian >>> rhythm >>> mechanisms are big news at present (molecular mechanisms), and one of >>> the best >>> analyses of the circadian control of an eye by the brain came from >>> Barlow and >>> colleague's work on the Limulus lateral eyes. There are at least two >>> other >>> sets of eyes in horseshoe crabs, one UV sensitive and one in the >>> telson... >>> >>> None of these conceptual advances were minor cul-de-sacs and all have >>> become >>> incorporated into the neuroscience base, ever expanding. Limulus >>> deserves great >>> respect as a unique and unusual pioneer invertebrate animal that ought >>> to >>> survive. What has the Red Knot done to gain comparable respect? >>> >>> So, if I had to curry up votes for one of the two endangered species, >>> it would >>> be for the unique and illustrious horseshoe crab, first. "Why save the >>> Red >>> Knot?" indeed -- do it second. >>> Steve >>> ****************************************** >>> >>> >>> Quoting Elizabeth Doull <edoull@ns.sympatico.ca>: >>>> Why save the Red Knot? >>>> PBS >>>> flocks of shorebirds, the red knot is fairly average looking. In fact, >>>> only the most practiced bird watchers may be able to distinguish this >>>> medium-sized, plump peep from the thousands of other shorebirds >>>> playing tag with the waves. Yet, somehow the red knot has caught the >>>> attention of people around the world. >>>> >>>> The knot's dependence on the eggs of the heavily harvested horseshoe >>>> crab has placed it at odds with another species -- humans. >>>> Conservation groups, lawmakers, fishermen, scientists, and ordinary >>>> citizens have all entered the debate. But even as our actions have >>>> imperiled the red knot, we can also preserve the species, by >>>> regulating the fishing industry and keeping clear of the beaches that >>>> the knots rely on during migration. Where nature ranks in our system >>>> of values will dictate how far we are willing to go to protect the red >>>> knot. >>>> >>>> There are millions of shorebirds in the world. Why all the clamor over >>>> the red knot? How could this small bird stir up so much controversy >>>> and inspire such extraordinary efforts on its behalf? To begin to >>>> answer these difficult questions we must first become familiar with >>>> the red knot. >>>> >>>> The red knot may blend in with the other small shorebirds, but it >>>> makes a journey that certainly sets it apart. A master of long- >>>> distance aviation, the red knot makes one of the longest migratory >>>> trips of any bird -- 9,300 miles along the Atlantic flyway from its >>>> wintering grounds in southern South America to its high Arctic >>>> breeding grounds. The journey is so exhausting, it requires two to >>>> three stopovers for refueling. The horseshoe crab egg feast they will >>>> consume at Delaware Bay, is not just an indulgence -- it's absolutely >>>> crucial for the birds' survival. When the knots arrive at Delaware >>>> Bay, their bodies are half their starting weight, devoid of fat and >>>> even some muscle. Here, the red knot will take about two weeks to >>>> double its weight so it can continue its migration. >>>> >>>> The migratory trip is far from the only risk the peeps take in their >>>> lives. The life of the red knot is fraught with challenges. In their >>>> wintering grounds of Tierra del Fuego, blinding gales blow up without >>>> warning, and tides surge 25 and 35 feet every 12 hours. The challenges >>>> facing the knots are even greater on the Arctic nesting grounds, where >>>> a declining population of birds makes it more difficult to find a mate >>>> and even if they do, a snowstorm can wipe out the knots' eggs. If the >>>> birds don't consume enough eggs during their migratory stopover, they >>>> may not have enough fuel to complete their trip, and those >>>> undernourished knots that do make it to the Arctic will arrive weak >>>> and emaciated. Add the fierce and unpredictable Arctic weather into >>>> the mix, and the birds are likely to be in such a state that it is >>>> nearly impossible for them to raise chicks. >>>> >>>> Researchers tag red knots in 'Crash: A Tale of Two Species.'Nature, it >>>> seems, has really stacked the deck against this creature. During its >>>> migration, the red knot concentrates in huge, densely-packed flocks. >>>> These enormous gatherings make the knots vulnerable to habitat >>>> destruction and, in South America, hunting pressure. Sadly, it is not >>>> just their eating preferences but their social patterns that put them >>>> at odds with human activities. >>>> >>>> All of these hardships have given rise to dire statistics. The red >>>> knot is a creature in peril. The U.S. Shorebird Conservation Plan >>>> lists the red knot as a "Species of High Concern," based on declining >>>> population trends and threats on non-breeding grounds. In the last 20 >>>> years red knots have declined from over 100,000 to less than 15,000. >>>> And in 2006, the knot was named a candidate for Endangered Species Act >>>> protection as an emergency measure to slow the rapid fall of its >>>> population. In the Delaware Bay, the knot has suffered a decline so >>>> severe that some experts predict the population stopping over at the >>>> bay could disappear within five years. >>>> >>>> Studies conducted outside of the U.S. do not paint a brighter picture. >>>> Counts of knot populations wintering in South America dropped over 50% >>>> from the mid-1980s to 2003. Researchers have suggested that the >>>> continued hunting of knots in South America might be partly to blame. >>>> >>>> The red knot is one of the world's most amazing birds. But if that is >>>> not sufficient motivation for us to save it, there are other >>>> incentives. Chincoteague, Virginia, a popular stop-over for the red >>>> knot, finds that what is good for migratory shorebirds is also good >>>> for Virginia business. A recent tourism survey found that birders and >>>> ecotourists were bringing in significant amounts of resources to the >>>> local economy. And one economic study in South Jersey found that the >>>> shorebird-watching industry generated nearly $36 million dollars in >>>> revenue for the area. >>>> >>>> Sadly, the issue raised in "Crash: A Tale of Two Species" over the >>>> increased harvest of horseshoe crabs remains contentious today. >>>> Whether the red knot will be able to continue to use Delaware Bay as a >>>> major migratory staging area in the future is still up in the air -- >>>> as is the fate of the knot. >>>> >>>> For more information on red knot conservation efforts, visit >>>> http://shorebirdproject.blogspot.com/, where Larry Niles (featured in >>>> "Crash: A Tale of Two Species") and an international team of >>>> scientists blog about the most recent news on the red knot. >>> >> >> >> -- >> No virus found in this incoming message. >> Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: >> 269.20.5/1278 - Release Date: 2/14/2008 10:28 AM >>
next message in archive
no next message in thread
previous message in archive
previous message in thread
Index of Subjects