Sunshine & dolphin madness

Gosh… sunshine AND feeding common dolphins! Yay! The mixture of sunshine and dolphins plus a large dosage of cabin fever resulted in a wee bit of madness…

A relatively quiet day on the RRS James Cook (equipment broke last night, and was being fixed today)… everyone busy sitting processing data at computers quietly, and blinking wide-eyed after discovering the sunshine outside. So we did long slow transects towing the temperature chain through the water (this is a long cable with temperature loggers at regular intervals from the surface to around 60m). I was processing some of the fish data, manually counting all the fish schools so that I can plot them, and see how they match with the bird data (see Andy Webb’s blog for a nice plot of the feeding gannets – nicely clustered over the bank where we’d measured lots of internal wave activity).

Meanwhile the birders were busy spotting… um… virtually no birds… though Andy did get pooped on while on watch :o) I went out for a spell of birding, and in 2 hours saw all of one or two fulmars, the odd gannet, one very distant bonksy… and then… Adam spotted, out of the corner of his eye a group of gannets hovering and swooping in the distance, and as we got closer we found a group of around 10 common dolphins feeding underneath the gannets (the gannets taking advantage of the fish brought the surface by the common dolphins). This activity resulted in much mad behaviour by the scientists (see photos to the right & below) & certainly I was grinning :o)

Right: Andy estimating the angle to the dolphins
Below: there are the dolphins! Silly tomfoolery after the event...

So that’s today’s blog… short and sweet… and compliments to the chef on a very excellent banoffee pie today!

Dolphins!

News hot off the press (it's nearly 1am BST)... Susan spotted a few dolphins alongside the boat in the dark :o) No species id... but first dolphins of the trip! Yay!
Thanks Susan :o)

The plan

I had a request today – to explain what the survey plan was. Hmmm, good question, the plan changes daily, hourly even – all dependent on the weather. However there is a general plan… the survey had been planned so that we’d hit one big spring tide (5th July) and one very low neap tide (13th July). A spring tide occurs when there is a new or full moon (moon lined up with the sun), which makes for bigger tidal currents, and a neap tide occurs half way between the new & full moons with smaller tidal currents. This results in more mixing (& more internal waves) at spring tides than at neaps tides. So the theory is that the spring tides mix the water up and bring nutrients to the surface, but the neap tides let things settle a bit and allow the phytoplankton to stay close to the surface & grow with the sun & make the most of the nutrients. This regular alternating between vigorous mixing and more settled tidal conditions makes our tidal seas as productive as they are… and this is what we’re here to investigate.

So I diverge a little. We cover a big spring tide and a small neap tide, so we should be able to see the contrast between the tides in the physics (we expect stronger & bigger internal waves at springs & lower at neaps), and in the biology (I’d probably expect there to be more surface feeding by seabirds during springs because the internal waves push the food to the surface – but I could be proven wrong). So, we chose a nice productive bank – Jones Bank (see map in previous blog) to look at these internal waves, and the associated physics & biology in three locations: on top of the bank (MS1), on the middle of the slope of the bank (MS2) and on the bottom of the bank (MS3). We also have a control site south of the bank by a few miles in a flat area (MS4) where we don’t expect the abrupt dramatic internal waves we’ve already seen on the bank edge (just some slow gentle internal waves).

So as part of this we do 25 hour stationary monitoring both on the bank and at the flat control site, taking regular measurements of turbulence through the water column (we expect more turbulence in internal waves, at thermocline boundaries etc.), plus a range of other variables through the water column: temperature, salinity, nutrients, dissolved oxygen, bacteria, phytoplankton, zooplankton (see previous blog), and probably other stuff that I haven’t found out about yet! In these sites we also take samples of the sediment, so that we can look at interchange of nutrients between the sediment & the water column & see if the internal waves have any effect on the productivity of the bottom, and therefore of course what critters are living in the sediment (so far it’s been sand or muddy sand at the bottom). We also have a camera that takes photos of the fish at the seabed (more of that later), and we also collect fisheries acoustics data & carry out visual watches for birds & cetaceans. These stations are carried out on the bank at spring & neap tides, and at the control site.

Then we have the ‘boxes’ (described yesterday) – surveying an oval 12 times over a 25 hour period, measuring oceanography (the temperature & salinity through the water column), fish & seabirds/marine mammals (if we ever see any of the latter). We’ll do these boxes on the bank both at spring & neaps, and at the control site.

One final activity is the dye release – but that’s in progress now, and quite cool… so I’ll concentrate on that in tomorrows blog :o)

...since there are no photos for todays blog I thought I'd put in a photo of the sunset I took yesterday...

Oooo check out those waves!

Today we’ve been going around in circles… well an oval really – an oval over the edge of the bank and back up again, one circuit every 6th of the tidal cycle for 25 hours – so we get two repeats of the tidal cycle over one day-night cycle. During these circuits we’ve been towing an ‘MVP’ – a Moving Vessel Profiler – which basically goes up and down the water column (hopefully not hitting the bottom on its way down!) measuring temperature and salinity through the water column. Also, we’ve been collected fish data using the echosounder & the birders have been busy with their binoculars… in a bit of sunshine! (well briefly – enough to make Mark get a wee bit sunburnt).

The physicists got very excited seeing some of the internal waves visible on the fish acoustics (I got excited too… check out the waves dude! Those fish are surfing the internal wave!).

What is an internal wave?… hmmm, well instead of a wave at the surface, it’s a wave at the thermocline – so where the warm light water sits on top of the cold heavy water (different densities – think of oil sitting on water) – at the boundary waves can travel (try it out – half fill a beaker with water & with oil, then jilt it a little and see if you can make a wave travel across the boundary layer between the oil and the water… I’ve not tried it – just thought it up so it might not work… but fun to try!). Anyway, these waves are basically caused by water flowing across bumps on the sea bottom and creating waves at the thermocline that travel, and cause mixing where they occur (turbulence), and so allow the nutrients from the cold deep layer to mix with the warmer surface layer, which is great for the phytoplankton (mini sea plants) & hence for the other critters in the sea. So well… that’s why we got all excited to see them on the fish echosounder… along with lots of fish (still trying to work out what species they are – but we’ll have fishermen coming along after us to fish & see what’s out here).

After all this excitement with the internal waves, I spent an afternoon with the birders to see if all this sub-surface activity was resulting in lots of birds and marine mammals. Alas not (still no dolphins, sorry)! We had a fun afternoon eating icecream and talking about sharks in supermarkets and dogs eating hotdogs (I guess you had to be there!), and were occasionally interrupted by the flitting storm petrels (look like bats darting across the surface – they’re tiny!), a few gannets & fulmars, a big fat bonksy harassing a young gannet, and some lovely Cory’s shearwaters (not seen them before – they come up from the Azores… goodness knows why in this July weather!) – but very elegant twisting and turning over the waves. The birders take this business all very seriously (check out Andy & Adam in the photo). And I enjoyed my relaxing birding afternoon, very peaceful (though I came in before the heavy rain!).

More fun tomorrow – more horrible weather on the way…

Been too knackered to blog...

Well, I’ve not updated for a few days, so I’m a bit overdue… been up to my eyes in fixing problems!!! So the last few days have been non-stop working, interrupted by meals (great food!) and sleep…

So what have we been up to? It all blurs together… let me check my activity log…
Ok, the weather calmed enough for us to finish deploying the moorings (4 in all), and yesterday (Sunday) started with a dawn CTD cast (measures salinity and temperature through the water column, and collects water samples through the water sample for all sorts of experiments by the other scientists (will find out more about their work & see if I can explain it in the blog later)). There were also bottom cores (takes a chunk of the bottom up for the benthic scientists to pore over), zooplankton collection…

…zooplankton… more of that now – it’s part of our project looking at everything from zooplankton – fish – marine mammals & seabirds. Beth’s in charge of zooplankton collection, and it involves towing something called bongo nets through the water (or the rest of us call them ‘giant’s tights’… because that’s what they look like (see photo on left)). These very fine nets are lowered through the water column to the bottom & then dragged back up & collects all the very small little creatures out of the water column – the tiny little animals that feed on plankton and other micro-animals… there are Calanus species (bugs that swim around very rapidly & vitally important animals in the food chain… species from sandeels up to 20-30m long whales eat these microscopic animals (I’m talking only the size of a millimetre or less)). Then there are the larvae of lots of other animals – so your baby crabs, baby fish, baby wormy things (which are cool – they look like translucent feathers that wiggle), and of course baby & small jellyfish… and lots more including cheatognaths… ever seen ‘Alien’ the movie? These translucent innocent looking creatures are actually voracious carnivores, and have a proboscis with a mouth on the end of it that comes out of their mouth to snatch up prey (thank goodness I’m not a zooplankton!) That’s just a few of the many creatures Beth found when she brought up her ‘tights’ out of the water. And it really is zooplankton soup out there … so much plankton (see picture on right of the inside of the end net – the cod-end... all that brown stuff is zooplankton)! Nice to see some life down there! COOL STUFF!

Why bother trying to find out about zooplankton? Well above the phytoplankton (micro plants), they’re the base of the food chain, so they’ll be the critters that attract fish that eat them, and the predatory fish that eat those fish, and the marine mammals & seabirds that feed on them all. So hopefully, where there are lots of dense aggregations of zooplankton we’ll find lots of fish, marine mammals & feeding seabirds (ok… I admit we haven’t seen any marine mammals and not much bird feeding activity yet… but well… that’s the idea anyway… and the weather has been a bit naff…).

Left: Beth & her zooplankton 'tights'

Lots more has been going on – we had a 25 hour stationary monitoring point during which Beth & I watched the fish echosounder and got overly excited by all the nice big fish schools, others got excited (or terribly bored) lowering and raising the turbulence profiler (aka the chimney sweep) through the water every 5 minutes, and the birders sat patiently watching the birds fly past. So lots of activities going on continuously – a real hive of activity. I’ll try and explain the different aspects as we go through the survey.

But now, after a beer in the bar, it’s time for bed… and tomorrow for more adventures.
:o) Clare

...bumpy seas...

Hello from the bumpy seas! Friday was a very bumpy voyage from Weymouth where we did the calibration to Jones Bank (see the map on left for our route – in black). So there were a lot of green faces (including me & I don’t usually get seasick!). However, there was still a hive of activity getting the moorings ready to deploy. The moorings sit on the seabed with instruments also spread through the water column, and then a big buoy at the surface. The moorings are placed along the edge of the Jones Bank (see map)… this is an area which is a fisherman’s hotspot – so there are lots of fish here, and it’s interesting to the oceanographers because of interesting tidal features which I’ll try and explain later in the cruise (in simple speak because I’m not an oceanographer!).
The moorings will be monitoring over the whole 3 weeks of the cruise lots of interesting things (well we think they’re interesting – that’s why we’re here!):

* ADCP = Acoustic Doppler Current Profiler (see picture on right)
A what? Well this sits on the sea bed and points towards the surface, transmitting a very high frequency sound pulse through the water which bounces off small particles in the water column (like zooplankton – your microscopic animals of the sea), and the reflection is picked up again by the ADCP. This allows the clever oceanographers here to work out how fast the currents are moving & in what direction throughout the water column. So it should show ebb and flood of the tides, as well as currents caused by the layering of the water column (where warmer water sits on top of cold water: the depth at which this occurs is called the ‘thermocline’)… and interestingly the currents travel in opposite directions on either side of the thermocline. This is great because it creates turbulence & mixing between the nice nutrient rich cold water, and the nice warm & sunny (????!!!) top layer – this means it’s good for phytoplankton – the little microscopic plants that allow our seas to be so full of life. Phytoplankton need both light & nutrients, so the thermocline is a good place for them in tidal places like here around the UK.

* Temperature loggers – these are placed at 5 or 10m intervals from the surface all the way to the bottom, and allow us to see where the thermocline is (where warm water changes to colder bottom water), and how it varies over the tidal cycle – both between the high and low tides, and between spring and neap tides.

* CPOD – a porpoise & dolphin click detector (Chelonia Ltd) is attached to each mooring (it’s the creamy tubular device attached to the moorings with lots of cable ties, jubilee clips and lots of gaffer tape curtesy of Em in the picture). These will detect any dolphin or porpoises within 1km of the mooring if they are producing echolocation clicks. Both dolphins and porpoises produce ‘echolocation’ high frequency clicks (higher frequency than we’re able to hear), which are believed to be used for locating prey & probably for navigation. A bit like the ADCP and the echosounder I’ve described: the porpoise/dolphin sends out click sound pulses into the water, and can acoustically ‘see’ fish, the bottom or even our ship from the echoes it hears. The CPOD will listen for & record these clicks so that we can see if there are any porpoises or dolphins around our moorings, and hopefully relate their presence to the oceanography we’re collecting at the same time… i.e. how does porpoise & dolphin presence change with the tidal cycle?

Gosh what a spiel! You can tell I have time on my hands! Well, two of the moorings went in last night before we were beset with 40 mph winds and an even bumpier sea… so that’s why I have time on my hands… we can’t do anything while the seas so rough! So now it’s a waiting game… waiting for the ‘unseasonal July weather’ to pass…

High tech scientists???

Hello from just off Weymouth! We finally set sail last night after spending the first two days loading equipment & getting it all set up… and enjoying our last beers on land for a month.

So day one…
If anyone thought that scientists were high-tech, think again! Today we spent the day trying to calibrate the echosounder that we use for finding fish. How does this work? The echosounder basically transmits a sound into the sea directly below the boat, this sound reflects off fish, allowing us to ‘see’ where the fish are in the water column. Sounds good so far? Also we use different frequencies to allow us to determine fish species: different fish reflect different frequencies by different amounts. So, for example, a cod has a swimbladder (an organ that inflates or deflates with air to allow it to move up and down the water column), reflects more sound at lower frequencies (your ‘bass’ sounds) than at higher frequencies (your ‘soprano’ sounds). To allow us to compare the echoes at the different frequencies for the different species of fish, and also to allow us to estimate how many fish there are, we have to calibrate the system… hence today’s task… headed by Sophie Fielding from the British Antarctic Survey (aka the acoustician), with lots of help from Viv, Mick (pictured with the trusty calibration ball), & Gareth our trusty fishermen.

So… calibration… hmmm that high-tech business… hmmm. This (believe it or not) involves dangling a ping-pong sized metal ball (tungsten-carbide sphere for those who want to know) on 3 fishing lines (on fishing rods) below the boat, and into the middle of the narrow beam of the echosounder (think of the sound being transmitted vertically through the water in a narrow cone shape). Well, no easy task by any means… imagine a bunch of rather stressed looking scientists & technicians poring over fishing lines and over the side of the boat, peering into the depths, making small adjustments to the fishing reel while muttering into a radio. That was calibration! Well plus a large dose of stress! Let’s put it this way… it’s challenging to try and get the ball to stay in position when you have a large tidal current pushing it against where you want it to be. Plus getting seaweed stuck on the ball doesn’t help get an echo back from it! But finally, after a long day starting at 4:30am and ending at 8:30pm we have 3 calibrated echosounders, & we’re ready for our fish! THANKS SOPHIE!

Now, sleep… and offshore into the windy weather that is coming our way… batten down the hatches!

:o) Sleepy Clare