Thought it would be worth a follow-up showing how much the temperature varies at L4 during the day (at the moment).  Unsurprisingly there is a very strong diurnal cycle at the moment with typical temperature differences (measured at around 1.5 m) being around 1 degC.  The most extreme difference was on 25 July where the temperature varied around 3.5 degC.  This was a combination of strong solar insolation (near perfect solar trace from the SPN1), little in the way of wind (< 2 m/s) and warm air temperatures (22 degC).  The data from the buoy are reported every hour, and shows the real value of having near-continuous data being streamed back from L4.

temp_14days

Last 11 days temperature measured at L4 buoy

 

temp_hum

Temperature and PAR – last 7 days: L4 buoy

wind

Windspeed and direction – last 7 days: L4 buoy

28th Jul, 2014

E1 and L4 temperatures

There has been quite a bit of attention in the media recently about the warm sea temperatures around the coast. Below see the plots for L4 and E1, updated with the most recent data. It shows that there is much more variability at L4 due to the strong effects of the tides. At E1 the temperatures are close to the maximum ever recorded (1908, 1976 and 1983 seem to be ahead at the moment).  To view the images properly you will need to click on them … asterisks represent the measurements made this year.

L4 temperature series (1988 – 2014)

L4_temperature

 

 

 

 

 

 

 

 

 

 

E1 temperature series – surface and 50 m (1903 – 2014)

E1_temperature

This time last year I posted a blog titled, “It’s Phaeocystis time again”. Well, they’re back and it’s exactly the same scenario as last year: timing of the bloom, presence of both P. globosa and P. pouchetii and large numbers of single cells (>25,000 per mL), particularly at 25 and 50 m depth, indicating the sinking and breaking up of colonies. This gets reflected in the fluorescence profile from the CTD, which changes from being a well defined line to a widely spaced cluster of data points which broadens with depth (check out the L4 CTD profile for 19 May 2014). There are still large numbers of colonies at the surface though. Coastal waters around Plymouth are looking a greeny brown colour and, on Sunday whilst out gig rowing between the River Yealm and the Mewstone off Wembury Point near Plymouth it was possible to see individual colonies floating in a cupped handful of seawater.

Given the presence of large numbers of Sunfish and the sighting of a big Leatherback turtle at the Eddystone, both chasing (!?) Jellyfish, is there anything that has changed with the water mass in the WEC recently? (Simon Thomas – 12 July 2013)

Numbers of Blue Sharks at record highs in the region off Plymouth (Glen Tarran – 17 July 2013)

The recent sustained hot weather has allowed large differences between the surface waters and deeper in the water column temperatures to build up. The temperature difference between the surface and the sea-bed at E1 is now 6 degrees C, varying between 18 degrees at the surface and 12 degrees at the bottom.

12th Jun, 2013

E1 Buoy Deployment

Despite heavy seas, 2.5m swell height, we managed yesterday to get out to the E1 station and successfully deploy a new buoy system.  The deployment was carried out by the Trinity House Vessel Patricia with the whole exercise being extremely slick and professional.  The mooring design for this buoy consisted of an 8 ton weight connected to the buoy with approximately 230m of chain.  When constructing a mooring the weak points tend to be the shackles used for connecting the various components together.  On board the Patricia we witnessed the method used to seize the shackles closed; once the shackle was connected in position the pin was heated until it glowed red hot and then two, large men, beat the pin with sledge hammers to mushroom it and thus prevent it from ever being undone.

The E1 Buoy is a collaboration between the Plymouth Marine Laboratory and the UK MET Office, replacing the existing PML buoy with a new purpose built platform incorporating the requirements of both organisations.  This deployment is the culmination of a project that has taken some 18 months from initial planning to final implementation and marks the commencement of a new collaboration with the UK MET office and particularly their marine division.  The project has highlighted a positive way forward in the sharing of expertise to deliver a state of the art multi user platform, thus saving on cost and maximising the potential of these systems.  It is hoped that the E1 buoy is the start of many more future collaborations between the Plymouth Marine Laboratory and the UK MET office in marine and environmental monitoring.

The UK MET Office is responsible for the meteorological parameters air temperature, humidity, atmospheric pressure, wind speed, wind direction, wave height and wave direction on the buoy.  The Plymouth Marine Laboratory has brought expertise to this project in the measurement of oceanographic parameters and is reporting hourly the sea temperature, salinity, dissolved Oxygen, Chlorophyll fluorescence, turbidity, Coloured Dissolved Organic Material (CDOM), Nitrate and Photosynthetic Available Radiation (PAR).  The data is already being received by both organisations and the Plymouth Marine Laboratory is currently working to present this data hourly on the Western Channel Observatory website.

6th Jun, 2013

Teeming with Ctenophores

Embarking on a kayak trip yesterday evening (5th June) from the River Yealm, Phaeocystis colonies were really evident in the surface water by the harbour office. They were not alone, however, as the water was also teeming with a great many ctenophores, ranging from about 1 – 6 cm in length. This combination of Phaeocystis and ctenophores was observed continuously at the surface down to the river mouth and then 4 miles along the coast to the east in Stoke Bay. This contrasts with station L4 this week where surface water and down to 10 m were observed to be clear (and there were very few single cells observed using flow cytometry) but water samples from 25 and 50 m were observed to have 100s of Phaeocystis colonies per 500 mL and 1000s of single cells per millilitre.

It’s Phaeocystis time again. Phaeocystis is a tiny 4-8 µm alga that forms colonies when conditions are right. The individual cells become encased in a carbohydrate gel matrix which can be a couple of millimetres in size, easily visible to the naked eye and contain 1000s of cells. These colonies can sometimes be clearly seen in coastal waters around the UK and can form blooms that are visible from space by remote sensing satellites.
This year, Phaeocystis started appearing at the sea surface at station L4 a few weeks ago and this week it has been found in large numbers (single cells and colonies) lower in the water column from 25 m to the seabed at about 50 m. What’s really interesting this year is that there may be two species of Phaeocystis in the Channel (see photos): Phaeocystis globosa and Phaeocystis pouchetii.
Phaeocystis globosa, is a temperate species and the species we’ve been seeing regularly off Plymouth for the past 8 years, whereasd Phaeocystis pouchetii, is considered to be more of a cold water, even arctic species, which may have made its way down through the North Sea during our cold winter. This ties in with the observation of cold water species of diatoms such as Chaetoceros teres (photo below) off Plymouth this year. (All photos, Claire Widdicombe, PML)

From Angus Atkinson – from email sent on 19/3/2013

What were you doing exactly 25 years ago?

Back then, L4 was just a bone in my lower back and E1 was a rock climbing grade. Some of us were probably in nappies. In March 1988 I was at BAS and the Plymouth Plankton Mafia were rivals at the time. We just laughed at their legendary tales.

Anyway, this afternoon marks 25 years of almost continuous weekly sampling of the L4 site, half way out to the Eddystone.  Over 1000 weeks of sampling is hard to imagine until you have done, like me, a mere 6 weeks of it. Blundering around in the dark on a wet winter morning…..getting out to Rame before turning back with the weather, then having to repeat this next day………. and that is just collecting the samples.

 What is the big deal about L4? Some time series are miles longer. Our E1 site further offshore has been sampled for a century, but most long programmes are neither regular nor continuous.  Some famous efforts like the CPR survey cover huge swathes of ocean, but the temporal coverage is coarse. Others seem to have it all – regular, long-term sampling of the whole planktonic food web (e.g. Helgoland), but these sites are often shallow, just outside the lab where the land has a huge influence on the sea. L4 does have it all. We are sitting on a gold mine.

 Since arriving at PML a year ago I have been a late gatecrasher to the L4 party, but we are all indebted. Let’s just pause a second and think of the multitude of people who carried L4 along through all these years.

 Angus

4th Mar, 2013

Winter zooplankton

Over the past few months we have noticed that we have two species of Calanus in our samples from L4. While Calanus helgolandicus and Calanus finmarchicus appear very similar to each other under a microscope, with just a slightly different head-shape and differing leg structure to tell them apart, their spatial distribution and ecological niches are quite distinct. Usually we would expect to see Calanus helgolandicus, a warm water species, but lately we have also seen Calanus finmarchicus, a cold-water oceanic species. Although Calanus numbers are quite low at the moment we are finding that C. finmarchicus are making up a large proportion of adult females, reaching 75% this week. At pretty much the Southern limit of C. finmarchicus distribution here in the English Channel it will be interesting to see how long these copepods hang around, their range is thought to be shifting northwards in response to increasing temperatures. Their numbers have decreased dramatically over the last 40 years, with consequences on the recruitment of important fish species such as cod that eat these nutritious little beasts.

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