[obol] Zostera japonica (aka dwarf eelgrass) - Request For Observations & Info

[Cindy Ashy]

Hello All.

Zostera japonica (aka Dwarf Eelgrass, Japanese Eelgrass) is a non-native
eelgrass that came in with cultivated oysters. In Oregon, it currently grows
mostly in the upper intertidal zone, prime shorebird roosting and feeding
habitat. At low tide when its short blades are lying flat, it gives the mudflat
a green hairy look. A picture of Zostera japonica, along with other non-native
species found in Oregon estuaries, can be found at the following URL:
http://web.science.oregonstate.edu/~yamadas/second.html

While Oregon has developed a plan to deal with Spartina and several groups seem
dedicated to controlling knotweed, it seems to me that Zostera japonica may be
flying a bit under the radar.

I would be grateful to hear from birders their observations of bird interaction
with Zostera japonica, particularly shorebirds (which is why I've waited to
shorebird season to post this). For example, do you see shorebirds avoid
feeding on the portion of mudflat covered with Zostera japonica as they work
their way down the beach? (I did in the Spring, especially with Whimbrels) I'd
be interested in which species do forage and which do not forage on mudflat
covered with it. Another example....do you see shorebirds avoid roosting on
mudflat covered with Zostera japonica as the tide comes in? (I have seen
shorebirds avoid mudflat covered with the stuff in Sallys Bend...especially
peeps...they seemed to fly away as soon as all the areas that weren't covered
with Zostera japonica were underwater, even though there was plenty of beach
left for roosting).

I would also be interested in any changes to invertebrate fauna you may have
observed in areas that have become overgrown with Zostera japonica....even
something as general as there seems to be less burrows.

I am interested in learning more specifically where this is growing in Oregon
and information about how extensive each patch is. If you know of any efforts
to eradicate this non-native or even people talking about such a plan, please
let me know.

For those of you who birdwatch in the Yaquina Bay area, there are large patches
of the stuff in Sallys Bend. There is also a patch on the Hatfield side of the
bay.

I think the importance of early detection and early eradication of non-native
species from both the ecological and economical perspective can not be
over-emphasized. However, getting people committed to actually doing these
types of projects early on before they become more of a problem is a real
challenge. So far, Zostera japonica has not been a real threat to commercial
species but neither was Spartina in Washington in 1990 when there was only a
"small" patch which could have been removed by digging....now their only hope
of eradication is the aerial spraying of herbicides which are non-species
specific and is costing millions....but then there is the problem of how do you
fund the removal of non-natives that aren't impacting commercial
species....maybe we focus on the  loss of mudflat habitat and how much cheaper
it would be if we catch it early?

I will be happy to post a summary of all observations reported to me/OBOL. I
read OBOL almost daily so if you want to post your observations to OBOL
directly I will see them...or you can use the email in my sig. Thanks in
advance.

Your observations could be end up being helpful in convincing people to develop
a plan for this non-native species.

Cindy Ashy
tunicate AT yahoo.com

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