COAST publishes regular newsletters highlighting issues relating to the marine environment of Arran the Clyde, Scottish and international, coastal waters.
A long winter yields some exciting new footage and species for Lamlash Bay by Leigh Howarth York University PhD researcher.
Every summer, for the past four years, I have been responsible for conducting a series of marine surveys in and around Lamlash Bay No-Take Zone. These summer surveys are the highlight of my year and I consider myself very lucky to have such an exciting, active job. I jokingly tell people that I arrive on Arran just as the sun begins to shine, and leave just before it starts to rain...in other words, mid-June to early September. However, I often get asked “What do you do in the winter?” or even get accused of “Well, I suppose that’s you done working for the year” followed by a remark about the laziness of students. However, although Yes I am indeed a student, and therefore do enjoy the occasional mid-day nap (who doesn’t?), the end of the summer’s surveys actually marks the start a very long, intensive process known as ‘the analysis stage’.
Picture: A ragworm (Nereis spp - encircled) co-habiting the shell of a hermit crab (Pagurus spp). Image taken from video footage captured within Lamlash Bay.
Last summer, we recorded over 40 hours of underwater video footage using our baited underwater video camera system (aka ‘the fish cam’). As it takes approximately four hours to analyse and watch one hour’s worth of footage, this gives me a total of 160 hours of un-edited viewing pleasure. Using the data generated from these videos, I can determine how the protection provided by Lamlash Bay No-Take Zone may be affecting fish populations. Initially, watching these videos is as fun as conducting the surveys (well almost) but after a few weeks it begins to drag. Nonetheless the endless, hilarious bickering and fighting between crabs, or large schools of mackerel, pollock, and sand eels that suddenly enter the shot and beautifully sweep past the screen always renew my interest.
I have just finished analysing last summer’s videos, which have generated some of the most interesting footage yet: large numbers of grey and red gurnards with their pointed heads and finger-like appendages walking across the seabed, a giant turbot defying physics as it flounders past the screen, a curious grey seal investigating the bait and then getting bored and swimming off moments after, as well as revealing a strange interaction between hermit crabs and a species of ragworm. I was watching a hermit crab scuttle back and forth when what I thought was an unusually long antenna wriggled and withdrew into the back of its shell. It turns out hermit crabs do not live the life of solitude I thought they did, but are often parasitized by long spiny worms several times the length of the crab. These worms live within the crab’s shell and feed on its host’s faeces and eggs. Being a biologist, I found this new discovery both disgusting and truly fascinating.
Picture: The wrinkled swimming crab (Liocarcinus corrugates), a species never before recorded in Lamlash Bay. Image taken from The Encyclopaedia of life.
By December, I had finished analysing all my videos, meaning it was time to move on to what I had been putting off since I had returned to York: the photoquadrats. These are simply 50cm x 50cm photos of the seafloor, taken in and outside Lamlash Bay No-Take Zone to form a permanent record of the state of the seabed. From these, I can work out whether the No-Take Zone is encouraging the recovery of seaweeds, maerl, corals, sponges and other fragile organisms. Every summer, we take over 1,200 of these photos, and every photo must be edited and analysed using special software. The work is monotonous and the pace slow. Every photo I finish analysing does not dent the mountainous pile of photos still left to do.
Towards the end, I feel my eyes will leave my head out of protest if they have to stare at another photo of the seabed. Still, there are many highlights to this work. The vibrant lush reds offered by forests of feathery red seaweeds grab the attention of every student who walks through my office. I have also started to discover small polyps of orange soft corals growing in areas where not so long ago they were excluded by the passing of fishing gears. February was a month of particular excitement after I discovered a species completely new to the Isle of Arran, the wrinkled swimming crab - Liocarcinus corrugatus. Then, a few days later, I stumbled across a photograph I had apparently taken last year of what appeared to be a cluster of some sort of white, translucent sea squirt . However, on closer inspection, each sea squirt contained hundreds of glistening capsules. After a few hours research I was delighted to discover that these were in fact egg capsules belonging to the common squid (Alloteuthis subulata). I had always pondered if squid occurred in the waters off Arran and now I had proof. The next step will be to conduct underwater video surveys at night, to see how great a density this species of squid visits the shores of Arran. Roll on the summer of 2013!
Visiting marine biologist Leigh Howarth is currently (July -Aug 2010) conducting the first diver scallop survey in Lamlash Bay to monitor the health of the scallop population since the introduction of Scotland’s first No Take Zone (NTZ). This will hopefully provide an important baseline for future monitoring of the Lamlash Bay NTZ.