Iceland Biology

Note: This program first aired on May 30, 2015. 

 

Today we hear more about Iceland, that mysterious high latitude island formed from volcanos, covered in sheep, and home to elves and other hardy folk. It takes a while to sink in while you are driving around, that you aren’t going to see any animals in the road, unless they are domestic sheep. Iceland has only one native terrestrial mammal, the arctic fox, and while the population is considered viable, they aren’t especially common.

So why no other native mammals? Reindeer were introduced on purpose, and mink accidentally, escaping from fur farms. Mice and rats accompany people wherever they migrate, but only the arctic fox, and humans, got to Iceland on their own. Why, for that matter, such low terrestrial biological diversity overall? Iceland has the distinction of having no amphibians or reptiles. Of the 1100 species of insect, the flies are the most numerous, followed by beetles and bees, while there are no ants or butterflies.

In the plant kingdom things are similar, there is relatively low diversity in vascular plants and bryophytes. The only native trees are a birch, a willow and the rowan tree, a species in the same genus as mountain ash. Only 10 species of passerines, perching birds, nest in Iceland. Even if you know very little about birds you could probably name 10 passerines without much trouble. The freshwater systems on the island host only 5 species of fish.

The answer of course is that Iceland is very isolated, and only recently unglaciated. The same ice age that covered much of North America, including Maine, covered Iceland as well. The difference is that once the glaciers retreated from Maine, Maine was connected to an entire continent populated by organisms ready to move in as climate allowed. Iceland found itself in the middle of the high latitude North Atlantic Ocean, and while the ice that connected it to Greenland and northern Europe allowed the hardy little Arctic Fox to tip toe its way across the ocean, nothing else made the icy crossing.

Only things that can travel by air, water, or animal can get to Iceland. Spores and very light seeds can be blown there if they get carried very high into the atmosphere. Other seeds can float and survive the ocean crossing if they are tough enough. The only animals seen on land that are found in relative abundance in Iceland are birds, and mostly sea birds at that. Which should be no surprise, as these animals routinely migrate thousands of miles, and are not stopped by air or water. The very lack of a land bridge for terrestrial migration is the reason they fly to Iceland. Essentially no land mammals means no predators; Iceland is an excellent place to lay some eggs right on the ground and call it a nest.

What Iceland does have in spades is marine biodiversity, hundreds of species of fish are found on its continental shelf, and over 100 species of algae grace its coastline. 15 or more species of marine mammals are found in its waters. What makes Iceland such a hard place to colonize, its location and latitude, make it a perfect spot for marine productivity. It lies right on the boundary between the polar and subpolar ocean currents, warmer water from the Gulf Stream and North Atlantic current especially warm the southern coast, while colder arctic water cools the north east.

The interplay between these two, combined with the large continental shelf extending out away from Iceland, mix the ocean and distribute the nutrients that drive productivity.

Humans have been exploiting this productivity for over 1100 years, Iceland was first settled by Vikings in 870 AD. Humans have been impacting the landscape ever since. The most significant environmental impact during Iceland’s 1100 year history has been soil erosion, primarily due to changes in vegetation that result from grazing. The shrubby forests found on the island retreated, and currently the vast majority of the island is used as open range land for the thousands of sheep that are raised there. The erosion impedes recovery of native vegetation, and the mild climate and short growing season don’t help either.

All of this dawns on you as you drive around the island, seeing birds everywhere, sheep and fences, but nothing else. There are vast stretches of land inhabited only by moss. After several days of just grass and stone I felt an explosion of sweet relief when we drove through some trees. Iceland is surrounded by hundreds of kilometers of water, and just kisses the Arctic circle. Biology has cobbled together an entirely respectable community of organisms to live on this chunk of rock in the middle of nowhere. I encourage you to check it out.

References:

The biological diversity of Iceland https://www.cbd.int/doc/world/is/is-nr-01-en.pdf

Iceland Travelogue

 Note: This program first aired May 23, 2015. 

This week, for you, a travelogue. Just two days ago I returned from a trip that people keep telling me is on their bucket list. My husband and I spent a week in Iceland, traveling around the countryside experiencing fjords, glaciers, lava rocks, birds and sheep. We soaked in thermal pools, saw mountainsides steaming, and smelled the overpoweringly rank sulfurous odor of boiling mud. Iceland holds a powerful spot in our imaginations, an isolated high latitude island, rife with volcanoes, short on humans, it’s a place we imagine magic can happen. I don’t know about magic, but the landscape is as weird and otherworldly as you think it is, with good reason.

Iceland sits right atop the mid Atlantic Ridge, a mountain chain that results from the Earth’s tectonic activity. 200 million years ago when the continents were bunched together in the super continent Pangea, North America and Europe began to move away from each other, a rift that would eventually form the Atlantic Ocean. As the continents part, new material rises from within the earth to fill in the seam between them. That seam is the mid Atlantic Ridge and as the continents continue to move apart, active volcanism along that seam continues to build sea floor and underwater mountains. Iceland however, isn’t an underwater mountain, it is above the surface and has been since about 15 million years ago. At that time the mid Atlantic ridge drifted over an existing hot spot, which is simply an anomalous plume of ultra hot material from the mantle that circulates up to the crust. Before the seam between Europe and North America drifted over it, this hot spot had been erupting and producing the huge volumes of basalt that make up much of Eastern Greenland, and the northern British Isles. This hot spot, in conjunction with the volcanism of the mid Atlantic Ridge has created enough volcanic material to produce an island, an island that is getting wider by centimeters each year as Europe and North America continue to move away from each other.

On the ground in Iceland what you see relating to all this volcanism is igneous basaltic rock, cooled lava, and ash. Driving along the southern coast you cross wide expanses of what is called sandhur, bleak and desolate outwash plains that result from floods that occur when a volcano and a glacier get together. All the material on this plane is volcanic gravel and sand, which is dark gray or black. Looking in one direction the featureless flatness stretches all the way to the uninviting North Atlantic, in the other direction are steep cliffs or glaciers. Other stretches of road run through lava fields, expanses of rock formed from liquid lava pouring over the landscape and cooled in place. These rounded bubbly formations host a thin skin of green moss, and the effect is a lumpy velvet covered wonderland.

The rock in Iceland is mostly volcanic, and much of that is basalt, a rock type that makes up most of the sea floor. When basalt cools from a liquid to a solid in the right circumstances, it will form columns, usually hexagonal but sometimes other shapes as well. Those columns are embedded in bed rock, so they don’t mean much to us until erosion happens and they are exposed. Iceland has lots of exposed basalt columns, columns with waterfalls going over them, columns in beachside cliffs, columns visible virtually anywhere rock is exposed.

All this volcanic activity and thin crust means that there is a lot of heat around, heat from inside the Earth. Iceland also has a lot of water, both in the form of precipitation and held in glaciers. And heat coming out of cracks in the earth, plus ample water equals one of my favorite things, hot springs. The island is criss crossed with pipes carrying hot water for municipal purposes, home heating and domestic use, electricity generation and most importantly for this traveler, geothermal pools.

Lava fields, desolate black sand beaches, columnar basalt, geothermal pools-it’s a landscape very different from my normal one but that is what traveling is for-to take us out of our normal experience and engage us in what is novel. The best travel stimulates reflection and forces you to rectify what you know with what you are seeing. I’ll share more of what I was seeing in Iceland next week.

 

References:

General reference on Icelandic geology, from the University of Rhode Island http://www.gso.uri.edu/lava/Iceland/Iceland.html

Hot spring smell, explained: http://hotspringsguide.net/why-do-some-hot-springs-smell/

Icelandic Institute of Natural History http://en.ni.is/

Great well kept up blog of current events in Iceland geology: http://www.jonfr.com/volcano/

A student project on the geology of Iceland, nice images and references: http://academic.emporia.edu/aberjame/student/brown3/iceland.htm

Nice overview of Icelandic geologic history, including funky translation: https://www.extremeiceland.is/en/information/about-iceland/history-of-iceland

On columnar jointing in basalt http://volcano.oregonstate.edu/columnar-jointing