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Hi Fred & All, Apr 3, 2013
Very interesting, especially the bit about the alien crab having a
beneficial effect and the Green Crab destroying Spartina beds. But what does
ditching have to do with this ? Just exposing more area to erosion or
something else ?
Yt, Dave Webster, Kentville
----- Original Message -----
From: "Fred Schueler" <bckcdb@istar.ca>
To: <NATURENB@LISTSERV.UNB.CA>; <naturens@chebucto.ns.ca>
Cc: "Naomi Langlois-Anderson" <nlanglois-anderson@nation.on.ca>; "Owen
Clarkin" <wrecsvp@gmail.com>
Sent: Wednesday, April 03, 2013 4:56 PM
Subject: [NatureNS] here's a fellow who's working on the effects of ditching
on salt marshes
> http://www.bertnesslab.com/html/people/Tyler.html - "Historically, salt
> marshes were thought to be controlled almost exclusively by bottom-up
> forces like temperature, salinity and nutrient availability. Over the
> past several decades, however, human impacts, like top predator depletion
> and eutrophication have shifted salt marshes to systems with strong
> top-down consumer control across the western Atlantic from the Canadian
> subarctic to South America. We have experimentally examined this shift in
> the control of salt marsh ecosystems in North and South America. Most
> recently we have focused a great deal of our attention on the
> consumer-driven die-off of marshes on Cape Cod and Long Island Sound that
> we have established is the consequence of intensive recreational fishing
> targeting top predators, depleting predator stocks near heavy
> recreational fishing areas, releasing the herbivorous crab, Sesarma
> reticulatum, from consumer control and triggering regional die-off of
> marshes associated with heavy recreational fishing.
>
> "This work challenges both the notion that marshes are under strong
> bottom-up control and that recreational fishing is an ecologically benign
> activity. We are continuing this work by following the spread of
> Sesarma-driven die-off into Long Island Sound, critically examining if
> the southern spread of Sesarma-driven die-off is also being triggered by
> recreational fishing pressure. We are also examining mechanisms of marsh
> resilience and recovery in marshes abandoned by Sesarma since the
> cordgrass food supply has been entirely depleted, and we are beginning to
> explore consequences of predator depletion in other soft sediment
> habitats where their impact may be just as great, but less conspicuous."
>
> I don't know how relevant this might be to NS & NB marshes, but it's
> something to think about, especially a new paper which suggests that a
> trophic cascade from alien Green Crabs feeding on the herbivorous crab,
> Sesarma reticulatum, may promote recovery of marshes...
>
> http://www.conservationmagazine.org/2013/04/welcome-visitors/
>
> Invasive species are usually the bad guys in conservation. But an
> invasive crab is helping to restore salt marshes on Cape Cod by forcing
> out more destructive crabs, a new Ecology study suggests. Along the New
> England coast, fishing has left many marshes bereft of predatory animals.
> As a result, marsh crabs that would otherwise have been eaten by the
> predators have multiplied. The marsh crabs have gobbled Spartina
> cordgrass along creek banks, making the land erode more easily. (DOI link
> at end of article isn't functional, paper is not open access)
>
> thanks to -
>
> Pamela Zevit, R.P. Bio
> Adamah Consultants
> Coquitlam BC Canada
> 604-939-0523
> adamah@telus.net
> Re-connecting People & Nature
> Science World - Science in the Classroom Ambassador
>
> ------------------------------------------------------------
> Frederick W. Schueler & Aleta Karstad
> Bishops Mills Natural History Centre - http://pinicola.ca/bmnhc.htm
> Mudpuppy Night in Oxford Mills - http://pinicola.ca/mudpup1.htm
> Daily Paintings - http://karstaddailypaintings.blogspot.com/
> South Nation Basin Art & Science Book
> http://pinicola.ca/books/SNR_book.htm
> RR#2 Bishops Mills, Ontario, Canada K0G 1T0
> on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
> (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca/
> ------------------------------------------------------------
>
>
>
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