Gone fishing...

On the offchance(!) that you aren't currently following the official Porcupine Abyssal Plain (PAP) Observatory blog, I thought I'd leave you a wee link to the post I wrote for them at the weekend about our trawling work. Enjoy!

https://papobservatory.wordpress.com/2015/07/06/gone-fishing/

Bringing the nets on board

The armoured grenadier, Coryphaenoides armatus, caught from 4850 m down!

Some of the other animals from the trawl catches. Left: Brittle stars (Ophiuroidea); Middle top: A sea cucumber (Holothuroidea); Middle: an Abyssal Grenadier (Coryphaenoides profundicolus); Middle bottom: an isopod; Right: A sea spider (Pycnogonidae)

Work, work, work (and sea monsters)

It's been a hectic two weeks.

Busy busy busy.

After the weather finally decided to stop chasing us around, we got ourselves over to our study site at the Porcupine Abyssal Plain to start what has probably been the most diverse range of deep-sea work I've encountered on a cruise! We've deployed and recovered environmental moorings, autonomous gliders, and a time-lapse camera ("Bathysnap") that's been photographing the seabed for the last 12 months; we've sliced mud, trapped amphipods and sampled a LOT of water!

Trawling in the Abyss

But the work that I came out here for was the trawling, and despite a couple of minor issues with the net along the way, we managed to catch ourselves a decent selection of fish which will help massively with confirming the species identifications of the fish I'm seeing in my photographs from the region. It's also a bit more data to add to our long-term dataset from the PAP which has been being added to gradually over the last 20 years and is one of only two such datasets to exist in the world, so all of this is pretty valuable.

The benthic fishes include the grenadiers (top four images) and eels (bottom image).

My primary interest is in the benthic fish (the ones that live on or close to the seafloor), like the ones in the image above. However, from a purely photographic point of view it's the pelagic or mid-water species that have been holding my attention over the past few days, because they are brilliantly monstrous little things! Here's a selection (most backgrounds have been photoshopped out and replaced with black):

Female Anglerfish

Female angler fish (head detail).

Gulper Eel (head detail)

Hatchetfish

As usual though, we unfortunately also collected a lot of litter in our catches. It's not surprising - this far offshore there are few regulations regarding the disposal of waste at sea (it's legal to dump most things once you reach international waters), but it's still a shame to think that even out here in an environment that is so distant from us, we're still disturbing and impacting it.

The litter brought up in our first trawl.

A coke can in the net.

 

 

I'm on a boat...

After a rather hectic weekend of data processing and frantic presentation-writing in time for a meeting yesterday, it's now time to pack up my rigger boots again and head to Southampton for another two weeks at sea for what is likely to be my very last cruise as part of my PhD.

Mud and muddy animals! Yeah! 

This time, we're heading back out to the Porcupine Abyssal Plain to learn how to trawl for sample in deep-water! I've done a similar trip before, but the guys who knew all the details of how to work the gear and get it properly set up are starting to leave or retire now, so there's a bunch of us heading offshore to gather as much knowledge as we can (and hopefully catch some interesting things while we're out there too!).

An abyssal grenadier almost 5000m down

As well as a lot of mud-sampling (it just wouldn't be a trip to the abyss without it!), we'll be conducting at least two seabed trawls and hoping to collect another batch of samples to add to the long-term dataset which has been being collected at the PAP site since the early 1980s to track temporal changes in abyssal animals over the course of several decades to improve our understanding of the fragility of those systems. As always, I'll be on the lookout for fish specimens to bring back with me, and will of course keep you posted on our progress as we go. Keep your fingers crossed for us getting good weather!

Ras Mohamed National Park, Nabq and Diving!

Yeah, my job is pretty awesome.

So like I said last time, I'm currently helping out on a Tropical Marine Ecology field course to the Red Sea with the University of Glasgow and so far it's been pretty stunning! The first week was spent largely getting everyone used to snorkeling around the local shallow reefs and learning how to conduct various underwater surveys (transects and point counts and the like) and being shown the different environments that are typical of tropical systems. To really show them what the coral reefs of the Red Sea can be like, we took a trip down to the Ras Mohamed national park at the southern tip of the Sinai peninsula for a couple of days, sleeping in a Bedouin camp and seeing what the place had to offer.

As always, please click on the images to see them full size (and nicer looking!).

Our camp for a couple of days at Ras Mohamed

We're definitely in Egypt.

It turns out it was quite a lot! The waters where we were staying dropped to over 800m within a short distance of the shore, so we were treated to some stunning drop-offs as the reefs disappeared off into the depths, as well as an abundance of fish and coral life. The photo opportunities were stunning and the water was clear enough to make it almost easy to take some really nice shots.

Looking over a shallow reef flat in Ras Mohamed.

Fire corals and amazing underwater visibility in Ras Mohamed.

One of our students snorkeling across the reef

The park was jammed full of fish and corals and the water clarity made photography almost simple!

After two amazing snorkels in the blue, we got to do a (freezing cold) night dive to see the nighttime behaviours of the reef inhabitants which was also awesome! Although it was far too dark for photography, the reef was alive with invertebrates (urchins, brittle stars, basket stars, shrimp and small lobsters) and nocturnal fishes which was really cool to see. Compared to the dominance of the fishes which you see through the day the change was remarkable and was probably one of the highlights of the trip (also I really like inverts!).

A raspberry coral in a seagrass bed.

Upside-down jellyfish!

The following day we heading back north again to the province of Nabq to visit a seagrass bed and a small mangrove to discuss their importance as coastal habitats and nursery areas. Just like when I did the course waaaaay back in the day in Tobago, the mangrove was full of upside-down jellyfish (that's actually their name, they weren't just normal jellyfish gone the wrong way up!) which I think are particularly cool beasties. Essentially, the name comes from their behaviour - they carry photosynthesising bacteria underneath their bell, which they use to create energy from the sunlight by turning themselves upside down and settling on the seabed in shallow waters. If the conditions deteriorate, they can just pick up and find somewhere else. They do still have stinging cells in their tentacles though which made the walk around the mangrove a bit prickly!

White mangrove trees. They have aerial roots which extend out of the (typically anoxic) mud and into the air and which they use to respire.

And after all that we got a day off on Tuesday before the student project work starts, which for most of us meant a day out on a dive boat to dive at a local shallow reef at Gab el-Bint which was ace. I'll just let you enjoy the photographs:

Anthias swimming around a gorgonian (sea fan) 

Anthias in the water column above the reefs

Anthias at warp one.

A coral hind (grouper) above the reef.

Anthias around a pitch-black crinoid (feather star).

 

Oddly, halfway through the dive we came across what appeared to be a small shrub with fish in it!* 

 

My dive buddy swimming behind a gorgonian (sea fan) 

Trumpetfish shoaling together at the end of the dive.

* It's really a dark green hydroid, but it really, really looked like a small tree.

Today we started work on the student's projects which they need to run for the next three days and then report back which means another busy few days for all of us, but should be good fun. My group are looking at aggression in anemonefish so it's an excuse to hang out on the reefs and take more photos for me!

Christmas tree worms on a coral.

A teeny tiny lionfish swimming over the reef.

Finally, it's worth mentioning (although it's pretty obvious) that the Canon G12 is working pretty well! The Canon housing isn't brilliant for very close-up shots because the front of the housing blocks half the light from the flash, but if you're willing to work around this it's excellent for shooting subjects >30cm away and framing them against a background. Alternatively you can just turn the flash off and use ambient light instead. As with all photography, getting good shots is all about knowing the limits of yourself and your kit and if you're willing to work within them it's pretty easy to get some great images, especially when your setting is the Red Sea!

Field work in Angola: Part 1

So, after three weeks away to the west coast of Africa, I'm back to tell the tale! But before I launch into everything that we did out there, I'd better give you a bit of background on why we went.

Part of my PhD work is looking at the effects of deep-water oil production on the behaviour and composition of fish communities over time. While shalllow-water effects have now been studied in depth for a number of years, there is virtually no data available on the effects that oil production in the deep sea (>1000m) may have on the benthic (seabed) fauna, particularly on mobile species such as fish.

In shallow waters, oil rigs are known to provide artificial habitat for a variety of fish species, and the abundance of fish at such oil platforms can be far higher than in the surrounding waters. This knowledge has led to programmes such as 'Rigs-to-Reefs' in the US which convert decommissioned oil platforms into man-made reefs to provide artificial habitat for fish and invertebrates as well as protection from fishing activities such as trawling. Many shallow-water fish species are attracted to vertical structures and will use such open, complex structures to hide from predators or as feeding grounds once the reefs become colonised by invertebrate life. Even while they are operational, static platforms still provide hard substrate for invertebrates to live on and for mobile animals to live in and around.

Fish attracted to a decommissioned oil rig.
Image credit: http://www.guyharveymagazine.com/

However, the role of oil platforms in the deep-sea and their potential for providing artificial reef habitats are as yet unknown. While we might expect the effects to be similar in deep water as they are in shallow water we need to consider a couple of important differences in the behaviour of the fish themselves and the type of oil production structures present.

In the deep-sea, there is relatively little hard substrate; the majority of the seabed is comprised of soft sediments like muds and clays, and is typically rather featureless, particularly in the areas targeted for deep-water oil production fields. Consequently, we could expect the fish species that live in these areas to have relatively low affinity for hard substrates since natural reef structures are rare, and therefore that the presence of any reef structure would have relatively little effect on aggregating those species without some other attraction (e.g. a good food source).
 
Secondly, oil production structures in deep water are physically very different to those in shallow waters, and tend to be far more spread out over the seabed. The oil wells themselves are capped by wellheads which are a few metres in diameter, and which connect via pipelines to a central 'hub' which in turn connects a flexible pipeline to a floating surface production vessel. This means that the actual amount of 'reef space' provided by the structures is relatively low compared to shallow, static rigs and it is therefore unclear how much of an effect this might have on local fish populations.

An example of a deep-sea oil field with surface production vessels.
Image credit: http://angolarising.blogspot.co.uk/2011/11/big-oil.html

This is where I come in. As a part of my PhD, I'm using data collected by two seafloor observatory platforms situated off the west coast of Angola in 1400m of seawater and installed by BP through the DELOS project. One of the platforms sits around 50m from an active oil well (the 'Near Field' platform) while the other is located approximately 15km away from any production activity (the 'Far Field' platform) and acts as a control site. The platforms each contain a number of 'modules' which hold time-lapse cameras, environmental sensors, active and passive sonar sensors and a sediment trap at the far-field and we can use these to investigate how the environment varies naturally over time at each site and whether we can see any effects of either the oil production structures or natural environmental change on the fish communities present.

The DELOS platform frame (image from www.delos-project.org)

An ROV conducting an inspection of one of the DELOS platforms

We've been collecting data from these observatories since February 2009, and although there were some early teething problems which needed to be resolved, we've now got a very nice dataset covering three years from an area of the world about which very little is known about the marine environment at all, never mind the deep sea! However, while the platforms are designed to operate autonomously for the most part, they do need to be serviced each year for routine maintenance (swapping batteries etc.) and to download the data that's been collected over the previous 12 months. This all means that once a year, technicians from Oceanlab (University of Aberdeen) have to head south to the Angolan capital city of Luanda, and then offshore via helicopter to the ROV servicing vessel, work around the clock to get everything done in as short a time as possible, reinstall the modules into the observatories and head back home again with all the data.

Sounds pretty straightforward doesn't it?

Well, this year I was finally able to join the technical team and head down there myself to see the equipment that's been feeding me data for the last two years and learn how it all gets done! It wasn't quite as smooth sailing as we'd anticipated though...

A tale of half a million photographs

Well, this week has been busy! After a couple of issues with one of the batteries, the AUV team managed to get Autosub working perfectly again and we've been conducting photographic missions to the seafloor over the last five days, covering a survey track approximately 150km long and taking over 500,000 photographs in the process! It's the biggest AUV survey of an abyssal  region conducted to date (to the best of my knowledge) which is very cool and I'm hoping it will allow me to examine the distribution patterns of fish on the seafloor.

Autosub6000 being launched!
(I love that they've had to write 'harmless scientific instrument' on it in case it's mistaken for a giant yellow torpedo!

Deep-sea fish (particularly abyssal ones) are pretty difficult to study, partly because as the depth increases there's less and less food available which means fewer and fewer fish are able to survive. So, by the time you reach the abyssal plains at 4000-6000m, there are relatively few individuals around to find. One way around this problem is to use baited camera systems to lure the fish into your photographs, and it is an extremely efficient way of assessing the abundance and diversity of scavenging species in an ecosystem. However, scavenging species only account for around 25% of the  total fish diversity in the deep waters of the north-east Atlantic, so we need to use other techniques to identify the other 75%. A potential solution is to use unbaited cameras (such as Bathysnap), set to take images every few hours over several months then record which species pass by the camera in that time. Alternatively, we could catch specimens using trawl surveys to cover a larger area (which has the additional benefit that we can get definitive identifications for the species we catch), but we can't tell exactly whereabouts each fish was captured along the trawl's path.


However, none of these methods are really suitable for examining what the distribution patterns of fish are on the seafloor (i.e. do they cluster together or are they spread evenly over the seabed?) or how they respond to variations in habitat (e.g. how they react to the presence of hills or hard substrate), which are fairly fundamental questions to consider in understanding the ecology of any species. This is where Autosub comes into the picture. 

The forward-looking camera & flash on Autosub which  I use to look for fish.

As an AUV (Autonomous Underwater Vehicle), Autosub can be programmed to dive to the seafloor, follow a survey route while operating any on-board equipment (like cameras or sonar systems) and then return to the surface and the research ship without requiring any human intervention during its mission. Not only does this free the ship to conduct other work while the Autosub is getting on with its surveys, but it can also be programmed to conduct extremely long or complex surveys which may not be feasible using other methods. For our work, Autosub was set to conduct photographic transects roughly 35km - 90km in length, taking photographs every 0.86 seconds at a speed of around 1m per second. In case your mental arithmetic is a bit creaky, that's approximately 4200 photographs per hour! 



EDIT: Hooray! I've had the OK to post a few images, so here are a few of the better ones. They're cropped from a 5MP camera so they're not amazing quality, but they do the job!

Bathysaurus sp. (lizardfish) is an ambush predator with rather a lot  of teeth. They're not really orange, but the camera has a funny colour balance going on that I've not fixed yet.

A (not-colour-corrected) grenadier from yesterday's mission.

And another little grenadier from the first mission we did.

Anyway, after a rather full-on five days or so of AUV operations and between the two stills cameras mounted on Autosub, we've amassed well over 550,000 images and covered around 150km of abyssal seabed! A preliminary look through the photos is showing a decent number of fish as well which is brilliant news and means I'm going home with a really nice set of (pretty damn exciting) data! All of this is exceptionally cool, but sadly combines with the 100 hours of ROV footage from last month's cruise to sound the final death knell for my social life. Well, that and the prospect of several weeks on an Angolan oil rig at the end of the year, but that's still to be confirmed...

Examples of the rubbish we trawled up from the Porcupine Abyssal Plain during last year's cruise.

One thing that takes the shine off all this cool and exciting research though is that despite the fact that we're conducting surveys in 5000m of seawater in an area which isn't commercially targeted for anything (no fishing, mining, oil drilling etc.), we're still seeing litter everywhere, from planks of wood and scraps of metal to canvas bags to old books and old drinks cans and bottles. Last year when we were out here we trawled up boots, bottles and twice as much spent fuel (clinker) as animals by weight. It sucks. You'd think that maybe somewhere as remote as the ocean abysses might just be far enough away from us that they'd still be relatively pristine, but it's certainly not the case out here.


Finally, Jen Durden and I have written up a blog for the NOC's 'Picturing the Deep' blog which will hopefully go up online tomorrow (Tuesday at the latest I'd expect) so you can see some of it there at least in the meantime! 

Heading back to sea!

I still can't quite believe I'm getting to spend so much time on research cruises this year! It's all very exciting! After the success of the Changing Oceans 2012 expedition which I was involved with last month, I've managed to grab a brief two weeks on shore before heading off tomorrow to join the RRS Discovery (the 50 year-old one, not the new one!) in Southampton to take part in the AESA cruise at the Porcupine Abyssal Plain (NE Atlantic). To give it its full title, the cruise is called:

Autonomous Ecological Surveying of the Abyss:

Understanding Mesoscale Spatial Heterogeneity

at the Porcupine Abyssal Plain

Which sounds pretty damn cool, doesn't it?

Essentially the aims of this cruise build on work we conducted on the RRS James Cook last August which aimed to collect preliminary data about the distributions of megafaunal animals across the abyssal seabed using an autonomous underwater vehicle (AUV). Unlike an ROV (a remotely-operated vehicle), which is constantly linked to the research ship via a tether cable and controlled directly by operators on-board, AUVs are pre-programmed with a route and details of what instruments to use and when, and then dropped into the sea where they will automatically follow their programming and then return to the surface when they're done. The lack of a tether system means that not only is the base ship able to continue working with other gears while the AUV is in the water, but that AUVs can access areas that are inaccessible to ROVs (e.g. under ice).

Image taken from the NOC website: http://www.noc.soton.ac.uk/aui/autosub.htm

The plan for the AESA cruise is therefore to send the AUV (we're using AUTOSUB) down to the abyss and send it off to conduct photographic surveys of the seafloor to assess how different animals are distributed across the seabed and how they respond to changes in the seafloor habitats (e.g. surrounding and on top of abyssal mud mounds) over a relatively fine scale. As usual, I'll be studying the fish that we see on the forward-facing camera, while others will be studying the invertebrate fauna using a downward-facing camera. Continuous surveying of physical environmental parameters will also be done at the same time. And while the AUV is busily collecting all its data, we can continue to work on collecting, processing and storing... you guessed it! Mud! I can't wait!

Deep-sea mud. Glorious, glorious, mud!

Since the RRS Discovery is the older sister-ship to the RRS James Cook, I'm expecting that we should have some (albeit limited) internet access while we're away, so I will hopefully be able to keep you updated on our progress and any other cool things we see as we go through the cruise. Also, since my research typically involves video & photographic analysis rather than lab work, I've made up a little side project of my own to run alongside the serious science! ... But you'll have to wait and see to find out what it is!