Saturday 31 May 2014

The Lesser Weever FIsh

The sea has calmed down and we’ve arrived in the final and largest survey area. We’ve continued to encounter a range of interesting species. Dogger Itch is not the only animal which we need to be wary of. In the last few days, we have also encountered the lesser weever fish. A picture of the lesser weever fish accompanied by the words ‘Weever Fish Stings’ was placed on the wall in the wet lab on the first day of the survey to warn the scientists to take care. The lesser weever fish has poisonous spines on its first dorsal fins and gills. Needless to say, we’ve being handling it with extreme care.

Lesser weever fish with its poisonous black dorsal fin.  

We’ve also encountered several crabs including the edible crab (Cancer Pagurus), the flying crab (Liocarcinus holsatus), the toad crab (Hyas coarctatus) and the hermit crab (Pagurus prideaux) with the cloak anemone (Admasia carciniopados). The cloak anemone envelops the hermit crab’s shell and increases the size of the shell. This means that the crab does not need to change its shell as it grows. 

Edible crab (Cancer Pagurus)

Flying crab (Liocarcinus holsatus)

Toad crab (Hyas coarctatus)

Hermit crab (Pagurus prideaux) with the cloak anemone (Admasia carciniopados).

Wednesday 28 May 2014

Beware the Dogger itch!

We have now moved into our third survey area on the Dogger Bank and we’re making good progress despite the best efforts of the North Sea weather, which has certainly picked up a bit from what it was.

Sampling the sea floor with the Van Veen grab in more idyllic conditions (S. Pearson, Cefas)

During our sampling so far, we’ve found lots of interesting sea floor animals including several starfish, flatfish such as the lemon sole and dab and various species of crabs and shrimp. We also happened to pick up a few animals that live in the water column above the seabed, including a few little cuttlefish which we couldn’t resist photographing.

The Little Cuttle, Sepiola atlantica (H. Hinchen, JNCC)

Working at sea has its risks, but you might not expect to face much danger handling the innocent looking creature pictured below. This is a bryozoan called Sea Chervil (Alcyonidium diaphanum). Bryozoans are a collection of tiny animals called zooids all living together in a colony. They often resemble plants more than animals and ‘bryozoa’ actually means ‘moss animal’. Each individual zooid looks like a tiny sea anemone, often having a ring of tentacles surrounding its mouth.

The Sea Chervil, Alcyonidium diaphanum, 16cm (A. Cunha, JNCC)

This particular bryozoan is said to cause the dreaded ‘Dogger itch’ when handled by unsuspecting fishermen (or scientists!). The Dogger itch is caused by a hypersensitivity to the sea chervil and can give you a nasty weeping rash which can last for months! As scientists we often like to get up close and personal with the animals that we collect; feeling their textures and looking closely at their characteristics. We’ll certainly all be careful what we touch after handling these specimens though, even with gloves on!

Monday 26 May 2014

Welcome to Doggerland!

If we were to sample the Dogger Bank SAC a few thousand years ago, we would be better off doing it by foot than on a ship. At that time, the area was dry land and formed a larger landmass which connected Great Britain to Europe known as Doggerland.

Map showing hypothetical extent of Doggerland (c. 8,000 BCE), which provided a land bridge between Great Britain and continental Europe (© Max Naylor)
The landscape would have looked very different from the extensive mass of water we see today; mammoths would be roaming through the tundra, and we might have encountered some humans running after lions with stone spears!

After the last Ice Age, around 8000 BCE, the north-facing coastal area of Doggerland had a coastline of lagoons, saltmarshes, mudflats, and beaches, and inland streams and rivers and marshes, and sometimes lakes. The archaeologists studying the site think that this was probably a rich habitat with human habitation and may have been the richest hunting, fowling and fishing ground in Europe in the Mesolithic period!

The Dogger Bank itself, an upland area of Doggerland, is believed to have remained as an island until at least 5000 BCE. After the end of the final glacial period of the last ice age, rising sea levels gradually reduced it to low-lying islands before its final abandonment, perhaps following a megatsunami caused by the Storegga slide – a submarine landslide off the coast of Norway. Nowadays the shallowest tip of Dogger Bank is below 20 meters of water. It is still a very rich fishing ground mainly for flat fish and sandeel.

A piece of peat with holes made by bivalves retrieved from the Dogger Bank seabed (A. Cunha, JNCC)

Some fishing vessels operating in the area today still occasionally drag up remains of mammoth, lion and other land animals, and even small numbers of prehistoric tools and weapons. This prompted the team to be on the look out for any suspicious objects while going through the benthic samples retrieved from the seafloor, in the hope of finding some interesting archaeology.

Fragments of peat retrieved from the Dogger Bank seabed (A. Cunha, JNCC)

Until now we haven’t been that lucky, although we have been finding little fragments of what we think could be pieces of peat, charcoal and even fossilized trees (although no one on board is an archaeologist!). Maybe we are being too creative but it is exciting to think that we are actually floating over such an amazing place.

Unidentified fragments, possibly charcoal pieces... (A. Cunha, JNCC)

Friday 23 May 2014

A bird in the hand...

by Becks Hunter

We’ve moved on to our second survey area and have left the tropical conditions behind. Night shift battled through seven hours of sieving in heavy rain under rough conditions. Now is the time to test who really has their sea legs!

Some of our most interesting finds include pogges (Agonus cataphractus) and sea mice (Aphrodita aculeata). These marine critters obviously aren’t actually rodents, but are a species of segmented worm. They are covered by a characteristic ‘fur’ of bristles and chaetae. Some of these are iridescent, giving the sea mouse a blue/green shimmer.

Sea mice, Aphrodita aculeata 

We are finding a lot of hermit crabs as well, including some whose shells have been entirely taken over by Epizoanthus incrustatus, a colonial species related to coral. One larger crab climbed out of his whelk shell and gave us the unusual opportunity to photograph the whole body.

Hermit crab with Epizoanthus incrustatus

A hermit crab outside its home

At 5am this morning, during transit between stations, night shift were called upon to perform a high seas rescue mission. A Chiffchaff (Phylloscopus collybita) had flown inside the ship and was stuck in one of the tea rooms. We were able to catch it and take it back outside, although it didn’t seem to be in any rush to leave!

A Chiffchaff infiltrates the lab

Not quite Doctor Doolittle, but close enough

Wednesday 21 May 2014

Dog Days on Dogger Bank

Today marks our third day of sampling on the Dogger Bank Site of Community Importance (SCI), where we’re gathering evidence to help inform future monitoring options. Weather conditions have so far been exceptional with the water colour resembling what you would imagine seeing in some sort of tropical paradise rather than the North Sea!

Scientists and crew deploy a grab into the azure waters of the North Sea (A. Cunha JNCC)

At our first survey area we are collecting data for a Before-After Control Impact (BACI) study. This type of study is designed to experimentally test the effects of a particular event, such as closing an area to fishing or exposing an area to contamination. Samples are taken before the event happens both inside and outside of the affected area. The same locations are then sampled a period of time after the event to see if any changes can be measured. Sampling a control area is important as this helps us to say whether any change measured is happening because of the event or if it can be attributed to other variables or natural variation. 

Our sampling strategy involves collecting grab samples of the seabed to examine the animals living within it and get an idea of the types of sediment that are present. We’ve also been carrying out camera sledge tows and small scientific trawls to see what animals we can find living on the surface of the seabed. Sifting through the animals to classify them by species and size can be a risky business, with the swimming crab Liocarcinus being particularly pinchy! 
Handle with care! Liocarcinus crabs like to snap at the fleshy fingers of unsuspecting scientists... (A. Cunha JNCC)

Friday 16 May 2014

Offshore survey of Dogger Bank Site of Community Importance

On the 17th May 2014 another 20 day JNCC commissioned survey will commence aboard the RV Cefas Endeavour to the Dogger Bank Site of Community Importance (SCI) in English offshore waters.  Dogger Bank is one of the 20 offshore candidate Special Areas of Conservation (cSAC) in UK offshore waters and is located in the Southern North Sea, approximately 150km north east of the Humber Estuary (see map below).

Map displaying the MPA boundary and sandbank feature.
View and download spatial data for this MPA on the JNCC UK MPA interactive map.

The Dogger Bank is the largest sandbank in UK waters and extends into both Dutch and German waters. It is home to a variety of species which live both on and within the sandy sediment. This includes segmented polychaete worms, shrimp like amphipods and small clams which burrow into the sand. Animals like hermit crabs, flatfish and starfish also live on top of the sandbank. Lots of long thin silver sand eels can be found on the sides of the sandbank and are food for many seabirds, whales and dolphins and other fish such as cod. The aim of this 20 day survey will be to gather evidence to help inform monitoring options for the site.