Today we began with oxygen-free bottoms off the Mississippi River delta. Mississippi has a catchment area covering more than 40% of the U.S. and even reaches in to Canada. Totally awesome! What the researchers have seen is that when large masses of fresh water floods into the sea, after Heavy rain and storms, zones are formed that are completely anoxic, lasting for various length depending on amount of water. Clifton Nunally is working in the area, known as The Mississippi Dead Zone. Dramatic!

Karin Troost from Holland asked whether the pacific oyster (Crassostera gigas) is taking over mussel beds in the Wadden Sea off the Dutch coast. It seems to vary depending on where along the coast they are investigating. Eastern Wadden Sea is now heavily dominated by oysters, but they also create a substrate for mussels, so the result is mixed beats with both mussels and oysters.
In the western Wadden Sea, oysters have colonized areas outside the mussel banks instead.
It seems like there is no need to worry, the oysters will not outcompete the mussels. They will move in and create mixed banks, with more complexity than before. What we do not know yet is how oysters moving in will affect the birds that eat the mussels. Will it be more difficult for them to access mussels? Also, oysters have incredibly sharp edges which birds might rather avoid. The question is also whether there will be food for both oysters and mussels to grow properly, something that Karin is working to calculate.

Sarah Ann Woodin from the U.S., now retired (which does not mean that she no longer does research), show how they have mapped the distribution of larvae from the polychaete Diopatra along the European coast (yeah, she has been sponsored by NASA). This worm builds lovely pipe-formed houses out of shell pieces. The worm larvae spread both naturally through the ocean currents, but also by human impact, hitchiking on mussels that are moved between different cultures along the French coast. It is an incredibly large study, but the advantage is that they get to eat as much mussels as they like while they are working. Wonder if they need an assistant?

In the afternoon, our Estonian colleague Jonne Kotta talked about the importance of temporal and spatial scale when talking ecology, and on what scale you are seeing changes caused by the climatic conditions. Changes on land, like the floods that hit Europe during the last year, for example, are obvious and get a lot of media attention of course. But the changes that occur in the water is not as high profile, and not as well mapped. Jonne has been part of mapping much of the Estonian coast. Once again, the problem with the absence of high-resolution maps of the sea, that we only see tiny parts of the seabed and that the amount of modeling required also need to be checked with actual observations, is discussed.

The second (and last) female plenary speaker of this conference is Cindy Lee Van Dover, who is working with hydrothermal vents (like chimneys of hot water from volcanoes on the sea floor). Her presentation is about the impact humans have on these communities as they mine these habitats for minerals. These environments enriches several minerals from sea water and can grow very large. One such, Godzilla, was 15 storeys high (!!!) before it collapsed during a small local earthquake in 1996.

It’s incredibly exciting with deep-sea research, in which ecosystems are not based on plants that capture solar energy, but is entirely chemosynthetic, wich means that they are instead based on sulfur. Cindy shows stunning images of volcanoes erupting under the water and what it looks like one, two, and three years later, when the animals will return and new structures are forming.

There are one or two embarrassed laughs as she shows different categories of trash you find in the deep sea around these environments. Most are scientific instruments left behind. Luckily, they are mostly classified as less disruptive to the environment. Since this type of environment was discovered 34 years ago, scientists have made more than 700 visits down to there. It leaves a lot of research equivalent of coffee cups and cigarette packets.

So, the problem arises if you venture to mine for minerals, mainly sulfur in these areas. When structures that are built up of mineral deposits disappears, the animals that depend on those structures for living environment and nutrition also disappears. Mining the sea floor also means that it whirls up a lot of sediment, something that many animals do not appreciate. The actual process of mining today, includes pumping shallow water down to the depths, causing a chemical imbalance.

Cindy does not condemn the mineral mining, which has not actually started yet in the areas she works with, but is concerned that they should set limits on how much of these unique environments you are prepared to lose and ensure that these limits are followed before embarking. Here’s a chance to do it right, or at least make minimal mistakes.

Hege Vestheim, originally from Norway, does research on deep sea brines (super salty water layers) in the Red Sea at Saudi Arabia’s University in Jeddah. Hege has investigated 25 deepwater basins along the Saudi Arabian coast that has extremely high salinity. Here, the environment is so extreme that they found no life at all in some of these basins (a dead octopus does not count). In some of them they found arrow worms (Chaetognatha), a clam of the family Solemya and some small anemones that sat on a protruding structure. But as they explore these salt pools they find more and more species, and we were shown an ROV video from some of the pools at more than 1000m depth, with several fun new species. Cool, Hege!