Arctic Tipping Points

Archive for the ‘ATP fieldwork in Greenland 2009’ Category

While our colleague scientists from the ATP project worked in Svalbard last month and explored the microscopic world of the water column, we will, in the coming weeks, explore the communities of kelp and seagrasses on the seabottom in the coastal waters around Nuuk, western Greenland and further north. Together with microalgae, the kelps (macroalgae) and seagrasses are the primary producers of the sea.

A forest of brown, red and green kelp appears below the surface of the sea – almost hidden for the observer on land, who only gets an impression of this underwater community at low tide when the uppermost kelps are exposed to air and reveal a distinct brownish belt along the shores. Below the surface the kelps can be several meters high, forming a jungle with flexible stem-like structures, intertwined among each other, moving with the waves, and carrying long brownish blades that constitute the forest canopy. Smaller kelps of red, brown and green colours form the under-forest, and right on the seabottom crust-forming algae may cover the stones and rocks as a paint of pink, red and brown. The kelps represent a diversity of forms, and many species take name after their appearance – ‘bladder wrack’ has air-filled bladders that make the blades float, ‘sea lettuce’ looks like green salad and ‘shotgun kelp’ or ‘sea colander’ is full of circular holes!

This underwater forest of meter long kelps appears even more extraordinary up here in Greenland where the vegetation on land is very sparse and most plants are only centimetres high.

Though kelps and plants share the ability to photosynthesize, kelps are not real plants and red, green and brown kelp also are very different taxonomically. Kelps do not have roots but most of them grow attached by a disc or root-like structures (haptera) to surfaces such as rocks or stones. They don’t have proper vascular tissue but their stipes and blades can absorb nutrients right from the water surrounding them. Moreover they produce spores not seeds.

While kelps grow on the hard seabottom, seagrasses form underwater meadows on the soft and sandy bottom. Seagrasses are real plants like the grasses on land with roots, underground stems and long slender leaves and they produce flowers and fruits underwater. Eelgrass is the most common north-Atlantic seagrass species, and we hope to find it in the fjord systems of Nuuk.

Seagrass meadows and kelp forests are important coastal ecosystems – they are productive, constitute the habitat and nursery area of many species and help protect the coasts against erosion. Kelp and seagrasses grow in the coastal waters from the shore and as deep as light allows – the clearer the water the deeper they grow. Kelp penetrates to larger water depths than seagrasses because all the cells contribute to photosynthesis.

During the next weeks we will collect kelp and eelgrass in the field and investigate their response to climate change. We will study their growth at Nuuk and subsequently compare it with studies further south and north in order to estimate responses to decreasing sea-ice cover and increasing sea water temperature along the geographic climate gradient from north to south. We will also test their response to warming by exposing them to a range of increasing temperatures, up to +9 ˚C which covers the full range of projected scenarios for surface temperatures in the Arctic by the end of the 21th century.

Sampling kelp, Kobbe Fjord, Nuuk. Photo Peter Bondo Christensen

An underwater forest, Kobbe Fjord, Nuuk. Photo Peter Bondo Christensen

Kelps exposed at low tide, Kobbe Fjord, Nuuk. Photo Peter Bondo Christensen

Kelp forest, Kobbe Fjord, Nuuk. Photo Peter Bondo Christensen

Eelgrass indeed grows in Greenland and even forms extensive meadows of dense, long shoots!
We had not seen any reports of Greenlandic eelgrass populations in the scientific literature, but a few inquiries among the local fishermen and employees at the Greenland Institute of Natural Resources revealed that eelgrass is indeed present here. They had observed it while fishing.

Lars Heilmann, technician and boatdriver at the Institute, guided us to a small patch of eelgrass in Kobbe Fjord, Nuuk. Finding this spot in the fjord demands pure luck or that you know the fjord like the back of your hand. Luckily, with the help of Lars, we could rely on the latter!

The small eelgrass patch in Kobbe Fjord. Photo Peter Bondo Christensen

The following day, Ujuunnguaq, a local fisherman, guided us to the inner part of the Godthåbfjord system to an extensive eelgrass meadow located in a bay next to the small village of Kapisillit about 100 km from Nuuk. On the way to the meadow we stopped in Kapisillit, where only 40 people live, and met Ujuunnguaq friend, Frederik, who contributed with more details on the location of the eelgrass meadows of the fjord. Our two local guides lead us directly to an extensive underwater eelgrass lawn with bright-green shoots reaching maximum lengths of more than 1 meter!

Nuria showing the large eelgrass shoots collected near Kapisillit in the Godthåbsfjordsystem. Photo Dorte Krause-Jensen

We took samples from the meadow that will allow us to characterise the growth of eelgrass here in the north and compare it to that at more southern latitudes. By comparing eelgrass growth along the geographical climate gradient we expect to obtain a hint of the response of northern eelgrass populations to a future warmer climate.

Birgit measuring the underground stems (rhizomes) of the eelgrass which leaves imprints of the past years production of leaves. Photo Dorte Krause-Jensen

As the Arctic warms and the sea-ice cover becomes less extensive and allows more light to reach the seabottom, eelgrass and kelps will most likely expand their distribution and their production and become even more important coastal habitats.

The initial results show that the Greenlandic eelgrass populations are at least as dense as populations further south but their annual production is lower.

Our team photographed in the village of Kapisillit. From left to right Peter Bondo Christensen, Birgit Olesen, Dorte Krause-Jensen – all from the University of Aarhus, Denmark and Nuria Marba from Imedea, Spain.

Our experimental campaign in Nuuk lasts 3 weeks. We live and work at the Greenland Institute of Natural Resources that also participates in the ATP project. Being located next to the sea with access to well-equipped and fast boats run by experienced boat drivers, a well-functioning laboratory, and inspiring and helpful employees, the place is ideal for studying the coastal ecosystem. Next to the laboratory is an annex building with apartments and individual rooms with common facilities for guest scientists and students. This is where we live during our stay.

The overall aim of our campaign is to obtain information on the growth of subarctic kelp forests and eelgrass meadows and their response to a future warmer climate where more light will reach the seabottom as the sea-ice retracts. Our activities incorporate field studies of the growth of kelp and eelgrass here in the north for comparison with that further south, since the present situation further south may simulate the future situation here in the north. We also conduct experimental studies of how kelps and seagrasses respond to increased seawater temperature.

For the experimental studies we have rented a cooling container from Royal Arctic Line and transformed it into a laboratory where we can grow seagrasses and kelp at temperatures ranging from the present summer seawater temperatures to temperatures up to +9 ˚C which covers the full range of projected scenarios for surface (air) temperatures in the Arctic by the end of the 21th century. The surface temperature of the coastal water around Nuuk is about 6˚ C in August and we had expected to use the temperature range 6-15 ˚C for our experiments. However, in the fjords where we sampled the vegetation the water temperature was typically around 10 ˚C so we decided to use the range 10-19 ˚C instead.

1. Our Royal Arctic Laboratory in front of the Institute of Natural Resources, Nuuk. Photo Dorte Krause-Jensen

The container awaited us in front of the institute when we arrived. The first couple of days were spent equipping the container with shelves, aquaria, temperature control units, heating systems, lamps, pumps etc. that we had sent in advance – also by Royal Arctic Line. Now the aquaria are populated with eelgrass and 3 species of kelp which will grow there for almost two weeks before we examine their responses to the warming. We have selected small individuals for the experiment so that we can fit them in our aquaria. The largest ones in the field are far too big – the biggest we found are almost 6 meters long! The three kelp species we use in the experiments are among the most dominant algae here and the same species also grow further south so we expect they will grow faster at the higher temperature treatments –up to a certain limit.

The container from the inside. Photo Peter Bondo Christensen

Close-up of the kelps and seagrasses growing in the aquaria. Photo Peter Bondo Christensen

A couple of weeks have passed and much has happened since the last blog. We have finalised our temperature experiments in the Royal Arctic Laboratory. Our simple temperature control system worked perfectly well and maintained our aquaria with kelp and eelgrass at temperatures of 10 (in situ), 12, 14, 16 and 19˚C. We grew 3 species of algae having different geographical distribution ranges, some extending to the south/mid coast of Greenland, others extending further north. During the last days in Nuuk we harvested the vegetation and measured survival, growth, photosynthesis and respiration.

The preliminary results show that some species like it hot while others do not! For example the intertidal kelp, knotted wrack (Ascophyllum nodosum) which has a geographical distribution range extending from Portugal in the south to Disko Bay on Greenlands midwest coast in the north, grew markedly faster when temperatures were raised (see figure below). Eelgrass also thrived at the warmer temperatures.

It takes 3 persons to measure 1 alg!! Photo Peter Bondo Christensen.

Birgit measuring eelgrass growth. Photo Dorte Krause-Jensen.

By contrast the subtidal kelp, longstiped tangle (Laminaria longicruris), which has a geographical distribution range extending to the north of Greenland, grew only slowly at the high temperatures (see figure) and some individuals died.

Since the temperature experiment ran well and took care of itself, the weeks in Nuuk also allowed time for field sampling. We sampled longstiped tangle and measured annual growth. Since the algae produce a new blade every year the growth can be assessed by the end of the growth season by measuring the sixe of the blade, and this was what we did. Some individuals had monster sizes (see photo).

We also sampled eelgrass and knotted wrack and measured biomass, density, growth and for knotted wrack also assessed age and population structure. Both species leaves marks that reveal their past growth. The underground rhizomes of eelgrass leave a mark for each blade that is produced and since the distance between marks is short in winter and long in summer it is possible to count the number of blades produced in a year. Knotted wrack produces a bladder every year so by counting the number of bladders we could assess the approximate age and by measuring the distance between bladders, we could assess growth. This demanded a lot of work and long days. Luckily we were 4 of us; Birgit had to go home to teach but Kitte came and assisted us with a lot of organisational skills and laboratory experience.
We now aim to compare the growth of these species in Nuuk with the growth at other latitudes in order to assess how growth varies along a climatic gradient and thereby get an indication of the response of the vegetation in the north to a future warming.

We packed down the royal laboratory and sent the equipment back home, but the work had not yet finished. The next leg of the program is that Nuria & Dorte join a 2-week cruise along Greenlands westcoast with MS FRAM, where they can sample during stops in settlements along the route. Peter joins another 2-week cruise in the Disko Bay with 3 colleagues to do vegetation and fauna surveys.

We, Núria and Dorte, joined MS FRAM on a 2-week cruise from Kangerlussuaq to Qaanaaq (Thule) and beyond – to the furthest north the sea ice allowed passage. The ship, built in 2007, is a very modern version of Frijof Nansens old FRAM expedition vessel from the late 19^th century. Though it is a luxury cruiser for tourists, ATP has the privilege to use it as research vessel! Hurtigruten which runs MS FRAM is part of the advisory panel of ATP and offered the project a cabin on each of the two Thule expeditions this summer and also a cabin on a cruise next summer. For ATP this is a great opportunity to do fieldwork along the western coast of Greenland and disseminate research on climate change. FRAM is also interested in having scientists on board and thereby offering the opportunity for the passengers to follow the sampling activities and listen to lectures on climate change and the Arctic marine ecosystem.

Our scientific aim on the cruise was to assess how the growth of kelp changes along the climatic gradient from south to north Greenland and use this information to provide a hint on how a future warming might affect the kelp communities in the north, assuming that current climate conditions in the south may move northwards.

The itinerary of FRAM with many stops along a wide latitudinal gradient is well suited for this purpose. We had planned a sampling scheme that was feasible during the relatively short time available at the stops in the settlements along the route, and which did not require fancy sampling and laboratory equipment. We needed a zodiac with GPS and depth sensor, a driver, an underwater video to explore the life on the seabottom, a rake to sample the kelp, plastic bags, ruler, pen, space to measure the several meter long kelp, and access to a freezer. FRAM provided us boat and skilled drivers at every stop as soon as the passengers had been brought to the shore. William and his colleagues became an important part of the team not solely by driving the zodiac but also by ensuring the best catches of kelp! Moreover, the bridge provided us temperature data, tidal tables and all kinds of logistic arrangements for the entire cruise, and the expedition team leader, Anja, settled the practicalities for sampling and lectures on board with her great organisational skills.

A catch of kelp. Photo Rudi Caeyers.

Our sampling site in Uummannaq. Photo Rudi Caeyers.

Since we did not know the sites in advance, we sought local knowledge on good places to sample. As soon as FRAM arrived at a settlement, we went to the shore and asked inhabitants for advice on where to find kelp. People were very helpful and also shared information with us about local ice conditions across the year. This help on kelp was very valuable and rendered the samplings quite efficient.

We got the opportunity to process the kelps at the sailors working space on deck 2 as well as next to the “Salon Panoramique” (deck 7) outdoors protected by the transparent wind screen across which we could admire the icebergs, glaciers, sea ice and occasionally a whale while navigating on a flat sea usually in sunshine… While working, the passengers and crew often approached us and inquired about the sampling and also shared experiences related to kelp and/or science with us. For example, a Greenlandic woman explained us how her family used kelp in their diet: they ate the big brown kelp, winged tangle (Alaria alata) and the red kelp Palmaria palmata prepared either as a soup or raw as a salad. Her favourite serving was freshly chopped Palmaria palmata with fresh mussels and seal blubber! Climate change also became a hot topic on board. Discussions took place in many languages: Scandinavian, English, French, Italian, German and we had to supplement our vocabulary with signs and body language. Parts of the discussions will even be translated into Czech when Czech TV releases a film about this trip.

Processing kelp on the 7th deck. Photo Rudi Caeyers.

In between the measurements we stored the algae cold in our minibar. Though we were eager to empty this minibar every night, we sometimes had to restrain ourselves and save some for the next day!

All in all we sampled 8 sites along the route. The preliminary results indicate that as we move northwards marine vegetation belts are narrower, the algae grow slower and some macroalge species disappear. These findings most probably reflect different climatic conditions. Ice cover persists longer towards the north, and laves less light for the macroalgae at the sea bottom and, concomitantly, seawater temperature decreases by several degrees during summer from southern to northern Greenland. With global warming we therefore expect southern kelp species to migrate further north and vegetation belts to expand.The two week cruise also offered many other highlights and set several northern records:

• we sampled the northernmost population of knotted wrack (Ascophyllum nodosum) at Qeqertarsuaq (Disko Island) , which we found thanks to the guidelines that Poul Møller Pedersen from the University of Copenhagen provided us
• we visited the northernmost settlement in the world, Siorapaluk, and
• we reached the northernmost latitude ever by this FRAM vessel: 79˚49’!

Núria sampling the northernmost population of knotted wrack (Ascophyllum nodosum) in Qeqertarsuaq, Disko Island. Photo Dorte Krause-Jensen.

We have now left FRAM and are on our way home while we write this final blog on the 5-week field campaign in Greenland in 2009. Thank you for your interest!

Núria Marbà and Dorte Krause-Jensen