[Coral-List] Mortality event at Flower Garden Banks
Vladimir.Kosmynin at dep.state.fl.us
Fri Jul 29 23:12:57 EDT 2016
Apparently water was 26 ppt when the die-off was discovered. Was it the only property of water masses that could cause mass-mortality of several taxa or there were other properties of water masses that caused it, remains to be discovered. Some corals can tolerate considerable drop in salinity, even below 26 ppt, but not for long time. For example, Siderastrea siderea can withstand such low salinity. It seems that water could be also anoxic. The origin of this water mass of such low salinity, and located at the depth of 20-30 m also needs to be traced. The distance from Mississippi River delta is about 300 km; eddies that can carry water from the delta westward and WSW are quite usual. However, nothing says that such event like what happened at FGB could happen in recent past; coral community in FGB consists of very large coral colonies, some of which are hundreds of years old. It seems that cause of reef mortality is not just the drop in salinity. Can the water masses from Texas and Mississippi delta, which, according to Frank, has moved over the FGBNMS area be anoxic?
Certainly would be beneficial to take water samples for the analyses not just at FGB, but also at adjacent banks and over the shelf north and east.
Vladimir N. Kosmynin
Date: Fri, 29 Jul 2016 14:23:51 -0400
From: Frank Muller-Karger <carib at usf.edu>
Subject: Re: [Coral-List] NEED ADVICE!! - ACTIVE MORTALITY EVENT AT
To: <coral-list at coral.aoml.noaa.gov>, Villy Kourafalou
<vkourafalou at rsmas.miami.edu>, Matthieu Le Henaff
<mlehenaff at rsmas.miami.edu>
Message-ID: <579B9F37.3020704 at usf.edu>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Dear colleagues -
I had sent this to the coral list yesterday (THURS 7/28/16) morning but
it seems it was not posted. In the meantime we are working with the
FGBNMS and the ONMS and the satellite data images to show how it
impacted different parts of the Sanctuary.
The FGBNMSanctuary is working on sampling waters and the benthos.
Also working with Villy Kourafalou and Matt Lehenaff to understand the
causes for the offshore dispersal of the plume in this area at this time.
My message to Steve Gittings and the coral-list yesterday ---
Hello Steve -
physically I am not sure what it is we can do but my sense is that water
samples be collected and examined for nutrient, oxygen, salinity, and
preserve it for analysis of toxic materials especially metals like
copper and heavier.
I don't think this is temperature or just temperature.
There has been a massive amount of rain over Texas and Louisiana over
the last few months.
The satellite images for this area over the past few days are pretty
poor due to cloud cover, but the images for several days ago show
massive amounts of coastal water from the LA-TEX area, likely also much
of Mississippi water, has moved over the FGBNMS area.
See these images:
We'd need to see if we can get better images, and build a time series
with anomalies to see how often this really happens.
The FGBNMS area normally does not get the direct input from the
Mississippi or coastal low salinity water - this water stays closer to
the coast. This year this plume offshore does seem anomalous.
__________________ FMK __________________
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