A Troublesome Visitor (Survey 0723S Blog #2)
By Rosie Clewett
Found out the latest from our offshore survey team in their second blog post on their visit to the Central Fladen Marine Protected Area (Survey 0723S), onboard MRV Scotia with the Marine Directorate of the Scottish Government.
We have been collecting samples of the animals that live in and on the seabed at Central Fladen Marine Protected Area (MPA) in conjunction with the Marine Directorate of the Scottish Government. To do this we use a Day grab to take a small sample of the seabed, and sieve away the mud or sand until we are left with just the animals (> 1 mm). We have seen a variety of different species (Figure 1), but there is one troublesome creature we don’t want to find!
Figure 1: Examples of the animals living in the seabed at Central Fladen MPA. From left to right: an ocean quahog, a phosphorescent sea-pen, a sea potato.
A hagfish (Figure 2) is a prehistoric worm-shaped fish that spends its days in near total darkness, swimming the muddy depths of the ocean, searching out rotting carcasses with its single nostril to sink its "teeth" into. Without eyes, it wouldn’t have a chance at seeing our Day grab coming.
It’s an unlucky day for all if our grab lands on a hagfish, as the hagfish gets rapidly transported away from its natural environment to the deck of the MRV Scotia, and us marine ecologists have to deal with the mess that it makes in our sample!
Figure 2: A hagfish we caught in our Day grab. You can see the slime it’s producing in a big globule in the middle of the bucket.
A hagfish produces a "rheopectic" ooze in mass quantities when alarmed, which means the more you move the goo around, the thicker and stickier it gets. This goo can glue our whole sample together into one big bucket-shaped mud cake!
As we need our samples to be able to wash through a 1 mm sieve, we remove hagfish as soon as we see them and swiftly return them to their natural environment. Thankfully most of our samples do not contain hagfish, and we have now successfully collected 134 animal samples from across the Central Fladen Marine Protected Area.
Figure 3: The Day grab we are using to collect sediment samples on this survey to Central Fladen, and a beautiful sunset over the sea.