Observations by Dave Conway last week:
“It seems to be quite a “jelly” year. We had large numbers of the ctenophore Pleurobrachia for a few weeks, but now we have massive numbers of the small hydroidomedusae Lizzia blondina and also high numbers of the siphonophore Muggiaea atlantica. With the recent sightings of large numbers of the ‘by the wind sailor’, Velella, at the surface, it is surprising there are any copepods left!”
22nd Jun, 2009
Early summer zooplankton at L4
8th Jun, 2009
Diving in Whitsand Bay
Did a dive on the James Egan Layne (max depth 19m) on Saturday and the vis was amazing – about 20m. Water temp about 13 degrees C. A really memorable experience being able to see so much of the wreck.
5th Jun, 2009
Underwater vis
In the past few weeks along the eastern coast of Plymouth we’ve been through the short snot like plankton stage, followed by the hazy misty like plankton and it now seems to be like diving in the tropics. The best vis is to the east whereas it’s a bit murkier in the Whitsand Bay area.
2nd Apr, 2009
L4 buoy hiatus
A few developments this week.
You may have noticed about 10 days ago the data stream from the buoy suddenly dried up. Our initial thought was that the radio-modems were playing up and Chris and Al went out in the RIB to solve the problem armed with a replacement unit. It was duely replaced but it turns out from the error messages that a power glitch cause the onboard PC to hang, a situation that we have now rectified and shouldn’t happen again (for that particular reason!). A great deal of these problems can only be sorted out post launch because even with the most rigorous testing we cannot know everything. Some changes to the scheduling have also been effected: the data acquisition is only for 30 seconds every hour and the data is only downloaded from the buoy every three hours as well to preserve the power and cut down on the likelihood of power problems.
The latest data should be appearing at:
http://www.westernchannelobservatory.org.uk/data/buoy/download/L4/
In addition I have manged to process some of the limited E1 deployment from last year. Some of the data is from Mayflower Marina (giving very high nitrate loadings as expected). This can be found at:
http://www.westernchannelobservatory.org.uk/data/buoy/download/E1/
Graphical representation of the data together with a web site is the next step … if anyone wants to do this whilst I am a way then please feel free.
The AIS also gave out at one point (probably a power issue too). The AIS can be tracked, thanks to Peter Walker via the development site:
http://wwwdev.npm.ac.uk/rsg/projects/interrisk/client/?sessid=f5fa1a9da8d28e2e91bcd2527cc741907ed96348
Clicking on the in-situ “latest buoy position” shows the buoy to be in place – and you can even look at the different ships as they sail around the channel (right clicking on the dots gives the ship’s name). This system will text us when the buoy moves out of position … which hopefully it will never do!
I’m off to sea now – so my last blog until June. Hopefully by then we will be in a position to deploy the E1 buoy.
Tim
30th Mar, 2009
L4 Monday 30th March, 2009
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- L4 buoy
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- Manned L4 buoy!
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- Rosette sampling with live graphs
L4 buoyManned L4 buoy!
- Rosette sampling with live graphs
We now have live data when we deploy the rosette sampler, depth, temperature, salinity, transmissometer.
Even though it looks calm from the pictures the buoy was moving about too much to safely check some of the components.
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23rd Mar, 2009
Diving vis reports
Although I haven’t been out diving myself this weekend the visibility reports from other divers are pretty good around the Sound. Out at Hilsea Point they reckon they had about 8m down at a depth of 25 m but the water is still a chilly 9 degrees C.
17th Mar, 2009
L4 databuoy now relaunched
After a winter of regrouping, replanning and something else allitoral(!) the L4 buoy was relaunched yesterday in near perfect conditions. It was very much, though, victory being snatched from the jaws of defeat.
All started off innoculously, with the usual radio chatter from the Navy complaining about the AIS giving an “off station” warning. We arrived at L4 around about 10.30 an proceeded to remove the temporary mark – only to find that it was only attached to one leg of the two point mooring. We attached the L4 buoy to the safe end and then proceeded to trawl for the missing end. For about two hours. What we decided to do then was to pick the entire mooring up (as it is in a triangle and by going all the way around it you can get around to the other side). Unfortunately when we got to the clump part of the mooring, a strop broke and everything went to the bottom. We were left with no ends! Never mind, the Quest crew are nothing but optimistic and nothing but resourceful. We trawled then for the joining wire between the two clumps. We got this within a couple of attempts and then completely re-layed the mooring from scratch. This enabled us to reconfigure the mooring the way that we have always wanted and also to attach the buoy. This entire operation was completed around 18.15 as the sun was setting. There had been no more margin for error! The crew of the Quest: Norm, Andy, Andy and Jim are to be commended for the brilliance and professionalism that they showed out there yesterday.
Oh – and if anyone is interested – the data is being posted on the web at:
www.westernchannelobservatory.org.uk/data/buoy and click on the folders to take you to the latest data. A proper web page will be put together in short order – but thought there might be some impatient people out there like me … and also the buoy shows up on the AIS receiver now too. So no sweepstakes as to when and where the buoy is likely to go and end up!
Tim
5th Mar, 2009
L4 temperature time-series
There has been a great deal of discussion recently about how cold this winter has been. Looking at the recent past it actually isn’t that much colder than 2006 at L4 and certainly E1 isn’t anywhere near the 6.7 degC measured back in February 1963. The coldest so far at E1 is 9.1 degC measured on 11/2 – but 2006 was colder with 7.7 degC measured on 15/3/2006. The next couple of weeks should see the coldest temperatures measured before the sun can get to work on the water column.
The attached contour plot allows us to put the entire water column at L4 into perspective – I will try and keep this up-to-date as the year progresses.
Tim
6th Feb, 2009
immortal jellyfish
Got the following email from Dave Conway this morning regarding his analysis of the L4 zooplankton:
There were a few Calanus finmarchicus around on the 5th and 21st January. On the 21st there was also a specimen of the “immortal jellyfish” Turritopsis nutricula. By chance I was reading an article about this in the Telegraph at the weekend, how it was spreading around the world – and then by chance it turned up in the next L4 sample I looked at. The Press were obviously tickled by the “immortality” aspect as I see there have been several articles on it recently. I have not found it at L4 in the last 2 years, but it is has been widely recorded in the English Channel for many years and previously at Plymouth, so it is no surprise to find it.
It is unusual in that the sexual medusoid stage can asexually produce a polyp that settles on the bottom and starts producing more medusae. Most medusa either bud of new medusae asexually, or more commonly produce eggs that when fertilised develop into a planula larva that settles and develops into an asexual polypoid stage, which then buds off medusae. Because an individual Turritopsis medusae can revert to the juvenile form and start producing medusae again, it can be considered immortal.
15th Dec, 2008
L4 sampling radius
Dear All,
Following our meeting last Thursday, Emmer Litt and Mike Grant have come up with the attached plot showing where we actually sample for L4. The circle represents the 1 km radius around L4. On the face of it there appears to be a great deal of drift. But it is very difficult to disentangle where the boat is actually doing the zooplankton nets, YFT etc compared with the simple rosette / optics rig deployment. Possibly more to discuss. I will post this on the blog as well so if people want to leave their comments there.
Tim