After a two day steam we arrived at the Hecate Strait sponge reefs and deployed the ROV for our first on-site dive. The goals were to get the hang of operating our instruments, deploy flow probes for calibration, and get sponge samples and mud cores for our on-board mesocosm experiment. This is the first time we’ve live streamed our dives and we’re very excited to be able to share our research with the country. Viewers had many questions about our operations and here are a select few:
by Evgeni Matveev
Why do we spend our time, energy, and taxpayer money to go to a remote part of Canada and study sea sponges? An important question, no doubt. Right off the coast of Canada are the largest and only known sponge reefs in the world; despite this there is very little known about this unique ecosystem.
The reefs were discovered by Kim Conway's team on accident in the late 80s, during side-sonar mapping of the sea floor. When they sent cameras down they saw expanses of glass sponges on an unforeseen scale. Glass sponges have a rigid scaffolding made of silica, and they have flagella that filter thousands of liters of water per day. By definition, a reef means that young sponges are growing on dead sponges, so this ecosystem has been in existence for thousands of years - some were estimated to be 6000-8000 years old.
Because we know so little about such an enormous and long-lived structure it’s crucial that we assess the role of the reefs in the Canadian Pacific ecosystem and determine the risk human activity poses to their survival. Data collected by us could be used used in the future for environmental policy design.
Like coral reefs, sponge reefs provide structure for other animals to live on. Sponge reefs teem with halibut, rockfish, squat lobsters, shrimp, and many other ocean creatures. The crevices of sponge exhalent openings and grooves of their body wall provide a refuge for small animals. A barren sea floor, conversely, exposes the little creatures to predation risk. Stephanie Archer, Anya Dunham, and Mary Thiess from the Department of Fisheries and Oceans (DFO) are on this expedition to research the role of sponge reefs as habitat for other animals. They brought hydrophones (underwater microphones) to listen to the chatter on the reef and compare it to the noise levels off reef.
Video transects will then be analysed to get a measure of biodiversity, and compared to the audio recordings. The idea is to determine whether hydrophones are a viable option for quantifying the number of animals that live on and off reef. Eventually this will allow us to assess to what animals are living on the reef even when we can't be there with the ROV.
Additionally the DFO team is trying to determine what role sponges play in the reef food web. By analyzing carbon and nitrogen isotopes of various animals they're hoping to build a food web structure and establish where sponges fit in. In an on board experiment, they'll also try to chemically label sponge excrement and see if any animals eat it to determine how important sponges are in the food web of the reef.
Lauren Law from the Leys lab is also here to study a reef community structure but in a addition to how many, she asks what animals are present on the reefs. This question involves looking at video transects, and doing a meticulous analysis of the relationship between sponge cover and abundance of various macro-fauna. She is also looking at the diversity of sponges that make up the reefs by doing DNA barcoding. This is an important question because the community structure and biodiversity can give us an indication of how resilient this ecosystem is to environmental change.
Sponge reefs are key to the biodiversity we see throughout the Canadian Pacific, but they’re at risk from human activity. Sponges in the Hecate Strait are very delicate, and live in relatively nutrient poor waters. This means any disturbance will have profound effects on sponge health. Our preliminary results from the cruise in 2015 suggest that the sponges rely on the flow around them to alleviate the cost of pumping water through their filtering mechanism.
This year Sally Leys and Evgeni Matveev are interested in confirming these results by looking at the relationship of sponge pumping rate and oxygen consumption with surrounding flow. It could be that these sponges are so abundant in this area because tidal cycles along the continental shelf provide enough surrounding flow for the sponges to survive on little food.
A newly established Marine Protected Area (MPA) restricts trawl fishing in a "buffer zone" (Adaptive Management Zone) in the Hecate Strait to protect the sponge reefs. However, fishing trawls not only destroy the sponges themselves, but sediment plumes stirred up by the net clog sponge filters and stop their pumping. Since we suspect that these sponges are delicate and are already living in a low food environment, the sediment could be a stress that the sponges can’t handle. In an in-situ experiment, Nathan Grant from the Leys lab is planning on determining how various amounts of sediment affect sponge pumping. This study could help to establish how far the fishing boats should be from the MPA such that the sponges can pump uninhibited.
On our way to Hecate we stopped off near Malcom Island to conduct a test dive. The objective of this dive was to make sure ROPOS was functioning properly and handled our SIPs well, to train the ship crew for deploying and recovering the ROV, and to practice dive logging for those who haven't done it before. The dive went off without a hitch! Our team saw some sponges, sea cucumbers, anemones, and rock fish. Now we're on the second leg of our two day travel to Hecate Strait, and Chief Officer Ryan said we should arrive at 7:00AM.
Yesterday we had all hands on deck organizing the gear into various rooms based on the procedure they're involved in. Below is a walk through of the spaces we'll be occupying aboard the Tully.
Aft (back) Deck
The gear was craned onto the aft deck and we had to carry it from there. In addition to the ROPOS ROV, the aft deck houses two shipping containers full of ROPOS gear, a winch, and a crane. The deck is off limits to us while the crane is in use, but if we’re explicitly asked to help we must wear a hardhat.
Walking from the aft deck towards the bow (front) is the main lab. It’s the largest room and takes up the entire width of the indoor aft. Lab benches line the perimeter of the room, and there are two table islands in the center. Our laptops, printer and office supplies are primarily stored on the port (left) bench, our tools and some instruments on the starboard (right) bench, and ROPOS computers and screens are set up in the center. During dives, all our time is spent here furiously logging our dive, but because we deal with so much water sampling during the rest of our procedures we use labs a little further from expensive electronics.
Water Processing Room
The SIP room has a door that leads outside to a narrow starboard deck, and up the deck and through another heavy door is a corridor. On the aft side of the corridor is the small water processing room. Lauren and Nathan (and often Amanda) will be in this room preparing samples for Ammonia, DNA, TOC, and bacteria analysis. This lab is windowless and because of that has in the past been nicknamed a “dungeon” or “cave”.
Across from the water processing room is the Officer’s Mess (meaning dining area, not dirty socks). This is where the ship officers and science crew eat. There is another (equally nice) mess downstairs for the rest of the ship crew. The mess has two rules: 1. no hats 2. no dirty clothing. For lunch today we had quesadillas, Spanish rice, split pea and ham soup, and tapioca pudding.
Portside to the Mess is a long corridor running the length of the ship along which the science crew berths are. The berths have two bunks per room, a shower and bathroom, and a table with two chairs and a small couch. There’s a round window with latches. The Chief Scientist cabin is on the second floor and is larger than normal cabins, however this time Sally is graciously sharing her room with Amanda and Dafne.
Two flights of stairs up, above the laundry room, is an old cartography room that has been repurposed into more of a storage/general use area. This is where a lot of our instruments are stored and assembled.
The bridge is another floor up, and we’re allowed to go up provided we ask. The bridge is surrounded by downward tilted windows (why they’re tilted has not been explained yet), and crammed with various navigational tools. It even has a fancy steering wheel like on old ships.
Rooms at the bow of the Tully include a lounge (where we have our meetings), a gymnasium, and a sauna. There are many other compartments of the ship which we don’t frequent, but now you’re familiarized with the lay of the land aboard our home for the next ten days.
There's no question we feel privileged to join the CCGS JP Tully. The ship is just back in from an Ocean Networks Canada trip and so once the group has arrived from Edmonton (early flight this morning) and from Nanaimo, we'll start moving things to the ship.
The Leys lab has been exploring the sponge reefs off the coast of British Columbia. Using the Remotely Operated Vehicle ROPOS our team has been studying the ecology, physiology and behaviour of sponges in the newest Marine Protected Area in Canada.
Check in with us on our LIVE Stream!