Field season in full bloom

The days are just soaring by as the field season hits its high peak.

Helping us in this organized chaos is Frances Ratcliffe, volonteering marine biology student from UK. It’s such a help to have an extra pair of hands. We are very glad to have her with us.

Frances and bladderwrack!

Frances and bladderwrack!

The week before last was spent at the Askö laboratory, were we ran the Baltic Sea part of a two-station experiment wich will look closer on the effects of grazing snails on seaweed.

First, we put the seaweed (Fucus vesiculosus and Fucus radicans) grow a while without any grazers, in order to get undamaged tissue.

Seaweed growing

Seaweed growing

After a couple of weeks, we placed the tips in jars with gastropods (marine snails) and let them graze for a couple of days. We so hope that they were hugry and ate a lot, so that we can see the grazing damage under the microscope later on.

45 jars with gastropods and an even flow of water. Amazing what you can build with a pipe and some hose.

45 jars with gastropods and an even flow of water. Amazing what you can build with a pipe and some hose.

Once the seaweed was grazed, we collected some Ulva intestinalis, a green algae, and made it release its spores.

<img src="" alt="Ulva intestinalis spores makes the water go green.” width=”300″ height=”224″ class=”size-medium wp-image-910″ /> Ulva intestinalis spores makes the water go green.

What we hope to see is if the spores will be able to grow on the grazed surface of the seaweed.

<img src="" alt="We have seeded the grazed seaweed by poruing spores of Ulva intestinalis in the water” width=”300″ height=”224″ class=”size-medium wp-image-920″ /> We have seeded the grazed seaweed by poruing spores of Ulva intestinalis in the water.

Let’s keep our fingers crossed and hope that it grows!

The week that was and this week, is spent at Tjärnö laboratory on the other side of Sweden, were we are running the same experiment, but in saltier water and with Ascophyllum nodosum instead of Fucus radicans and with other gastropods.

Our lives have been made so much easier thanks to Marit, who is doing her master thesis together with us. She has tended to our experiment so that we didn’t have to go back and forth between the coasts like crazy. Thank you Marit!
Meanwhile, she has also done an enormous fieldwork on a very interesting study on gastropods and seaweed, that we hope to write more about here on the BalticSeaWeedBlog.

Marit shows her disected gastropods.

Marit shows her disected gastropods.

it is always nice to meet and talk about seaweed. We had many nice discussions on this fascinating topic.

Frances, Marit and Lena discuss seaweed at Tjärnö Laboratory.

Frances, Marit and Lena discuss seaweed at Tjärnö Laboratory.

Seaweed in the Quark is now mapped

The Finnish Forststyrelsen, together with Länsstyrelsen Västernorrland and FOI have developed a method using LIDAR and SCUBA diving in order to make more large scale mapping of fucoid belts in the Bothnian Quark. This is a very important tool in environmental monitoring, since this can be used in calculating more exactly the areas of seaweed affected positively or negatively by environmental change.
To see the nice map of Norrskär that has been constructed, click HERE.

Seaweed course in Denmark

The week has been spent in Denmark, on a full Sunday to Sunday course to learn more about macroalgae.
With a schedule so full you can hardly fit it to a paper, the hopes and expectations to become a real seaweed guru are high.
There are 11 PhD students partaking, all from different countries!
The course is arranged by Aarhus University, as you can see in their newsletter (sorry, only in Danish).

Our first day of the course, we went out to collect macroalgae in the field. We started at the pier next to Ebeltoft harbour, where the sun shone and it was lee on the inside where we were working. I took this years “first swim without a drysuit in Nordic waters”. It was a refreshing 16 degrees Celsius and I was in the water for about 10 minutes, collecting material. Here there were four Fucus species growing: Fucus spiralis, Fucus vesiculosus, Fucus evanescens and Fucus serratus. Jackpot!

Lots of seaweed!

Lots of seaweed!

After a field lunch of sandwiches, we headed north, to Grenaa. Here, the Marine Home Guard and their boat took us out on Kattegat! What a luxury! This is a new collaboration between the Home Guard and Aarhus University, so the Danish TV was out and filmed us. Click here and fast forward to 1:19 into the clip and there we are.

Monday evening and Tuesday was spent going through the collected material to determine the different species and look at their different physiological structures.
On Wednesday, we tried to reproduce sugar kelp ( Saccharina latissima ) by getting them to release spores. It didn’t quite go as planned, so we took some good old bladderwrack and got it to release eggs and sperm instead.

On Thursday, we went to Algcenter Grenaa and had a look around. Pictures from our visit you can see the Algcenter website

Anette Bruhn show us how they cultivate sugarkelp at the Algcenter

Anette Bruhn show us how they cultivate sugarkelp at the Algcenter

We also got to visit the Kattegat Center, located just across the parking lot. This is one of Denmark’s many fine aquariums that have long been on my wish-to-see list. It was just as good, if not better, as I had expected. There was even an exhibition of algae and their importance. It is totally worth a visit!

Friday and Saturday were devoted to compiling and analyzing all of our data, and then present it in four groups according to various themes (Taxonomy, Monitoring, Light and Cultivation).

Danish seaweed; red, brown and grøn

Danish seaweed; red, brown and grøn

Seaweed project within BalticSea 2020

Anyone who is interested in the Baltic Sea might have heard of Baltic Sea 2020 Foundation.
Baltic Sea 2020 is a foundation founded by Bjorn Carlson through a donation of 500 million SEK (55 million EUR). The Baltic Sea 2020 Foundation’s assets shouldfund projects that are action-oriented, innovative and helps to improve the knowledge of the Baltic Sea continuously until 2020. The BalticSea 2020 Foundation began its work in 2006 and has to date initiated more than 70 projects, of which 25 are ongoing.

One of these projects is about trying to re-establish bladderwrack inside Björnöfjärden, a bay outside Stockholm. Björnöfjärden is heavily eutrophicated and the water is quite turbid with particles that prevents the light from penetrating. It quickly becomes dark below the surface, so that only a few stands of seaweed survive here. Observant locals have informed us that there was plenty of seaweed in the Björnöfjärd in the past, however.

So, seaweed enthusiasts to the rescue!

Susanne Qvarfordt is ready to establish bladderwrack.

Susanne Qvarfordt is ready to establish bladderwrack.

Susanne Qvarfordt from the environment surveillance company Sveriges Vattenekologer has initiated a project that will examine what factors might prevent the seaweed population from re-establishing in Björnöfjärden.
In addition, she asked the BalticSeaWeed blog to help with our expertise!

So, during the first days of June, we collected fertile tips of bladderwrack. These were sexed (we cut the receptacles and see if they are male or female), so that we would get an appropriate ratio of males and females at each site.

Sexing seaweed is best done with a scalpell and a magnifying glass.

Sexing seaweed is best done with a scalpell and a magnifying glass.

The bladderwrack were made into small beautiful fertile bouquets which were then attached to a grid. These will be placed in the water, floating over a number of concrete plates, and hopefully make new small seaweed babies that can attach itself to the plates.

All is ready for a baby boom!

All is ready for a baby boom!

So, now we have placed three grids in Björnöfjärden and three in nearby Fjällsviks Bay, to see if any of the other actions carried out in Björnöfjärden will affect the seaweeds ability to reproduce.
So, keep your fingers crossed that no one gets caught with their anchor or fish tackle in our beautiful grids, and hope for calm weather at Midsummer full moon so that there will be many wee ones.

Placing a seaweed grid with buoys.

Placing a seaweed grid with buoys.

Around Gotland

Yessiree! It’s time to jump into the water again!

After a long winter with lots of ice, and a well deserved trip to warmer water, it was time for yours truly to submerge oneself into the cool waters of the Baltic Sea.

Field season 2013 opened on Wednesday 22 May at the scenic island of Gotland, jewel of the Baltic Sea.

For the faithful reader, it comes as no surprise that it was time for the inventory of summer reproducing bladderwrack around this beautiful island, as part of the investigation we made along the mainland coast and Gotland last year (see previous post on Tångbloggen 2012 – A seaweed odyssey).

Gotland is well known by many botanists for its amazing flora, and the orchids certainly fought for space with primroses and lily of the valley along the road as we drove north from Visby up towards our first stop just south of Lickershamn.

Orchis mascula- Early purple orchid

Orchis mascula- Early purple orchid

Unfortunately, I think most people fail to see how beautiful Gotland is below the surface. The clear water and the dense seaweed forests are magically beautiful and are conveniently found at knee-depth in the water. If you do not like to get wet, you can easily experience life below the surface with a pair of high rubber boots or waders and water binoculars.

Our second stop was out on the island Fårö, at Lauter huvud. At the moment it’s a rather low water level in the Baltic Sea. It is caused by the weather and is not unusual this time of year. But it gets a little tricky to swim when you are constantly running aground. It was easier to walk among the rauks and occasionally stick my head under the surface in order to verify single specimens of Fucus. Quite possibly the occasional tourist who stayed at the car park was wondering what we were doing. One is not exactly discreet in a bright red dry suit. Hope I did not destroy too many photographs by emerging between rauks like a jack-in-the-box.

Having swum a little off the cliff edge, where it goes from 0.5 meters deep to 15 meters, we went to today’s third and last site at Östergarn.

Here the waves rolled in with a quiet rhythm, and if I had not been busy counting, I would certainly have fallen asleep, it was so very peaceful. The sun had come out and warmed my back as I floated about. I saw plaice, viviparous eelpout (Zooarces viviparus), stickleback, and Lesser pipefish (Syngnathus rostellatus).

Plattfisken vilar bland tången.

The plaice is resting among the seaweed.

The night was spent at the nice hostel in Hemsedal, which had very comfortable beds.

Thursday morning began with a trip down to the southernmost tip of Gotland, the Hoburg. Here we encountered more nature lovers in the form of a flock of birdwatchers. The species often nests at the southern tips of both Oland and Gotland and is easily recognized by the telescope that is often worn over the shoulder.

I even saw Red-Backed Shrike (Lanius collurio), Northern Wheatear (Oenanthe oenanthe) and a yellow bird that I didn’t recognize.

The sea was calm and the swans that landed some distance away did not attack the red ball splashing around, muttering through a tube (snorkel). It was nice to see that htere were many small juvenile seaweed individuals there. Reproduction last year was apparently very successful. Always a good sign.

Our last stop for a dip was just south of Klintehamn. On the way there we visited the nice naturum center in Vamlingbo for a short break. With coffee in the body, we parked at what must be Gotland’s busiest road, and changed into work clothes.

“When you take off your pants, five cars and a bus will always appear” – Old jungle proverb

It was the only site with lots of bladders on the wrack! One might think that bladderwrack always have bladders, but no! If the site is exposed to strong wave action, no bladders are formed. This is to minimize wave grip, so that the wrack does not get torn off by the waves.

Blåsor på blåstången - inte en självklarhet.

Bladders on the bladderwrack – not always to be expected.

It was plenty of gammarids, prawns and isopods here, and I hope I got a picture of the Lesser Pipefish hiding amongst the seaweed. It was obvious that there is a lot of nutrients coming out into the water as runnof from land. The seaweed had much filamentous algae growing on them. Swimming across it reminded me of a shaggy rug.

After again having fulfilled the jungle proverb (Why?!?) we headed towards Visby and enrolled into the prison. If we get out tomorrow remains to be seen.

Dissertation time for thesis on Fucus radicans and Fucus vesiculosus

Friday 17th of May is not only the National Day of Norway to be celebrated, but also the doctoral defence of Daniel Johansson.
Daniel has studied at the Sven Loven Centre for Marine Sciences Tjärnö (more commonly known as TMBL) belonging to the University of Gothenburg.

Daniel’s thesis is entitled “Evolution of the brown algae Fucus radicans and Fucus vesiculosus in the Baltic Sea” and contains primarily work from a genetic point of view. There has been a lot of work put into obtaining the genetic identity of both species in order to distinguish Fucus radicans from Fucus vesiculosus, but also to be able to distinguish between different clones of Fucus radicans, which in the Gulf of Bothnia reproduces mostly vegetatively. This is achived by proliferation, small branches that fall off from the parent plant and then attach themselves to new substrate.

Small branches of Fucus radicans have formed rhizoids (sticky threads) that attach to the Petri dish.

Small branches of Fucus radicans have formed rhizoids (sticky threads) that attach to the Petri dish.

Daniel has also compared the ability of proliferation between different clones of Fucus radicans to see if the dominant clone, a female that has been found along 550 km of the Swedish Coast, was better than the other clones.

The defense starts at 14:00 in the Auditorium at Tjärnö, of course we will be there to listen!

Spinning eggs for Easter

I am going to render a normal conversation that often happens when I talk about seaweed and what I do.

– So, you work with seaweed. Nice! What do you do with it?
– Well, among other things I try to cross different species with one another in order to understand how speciation occurs.
-That sounds interesting. When does the seaweed bloom, then? Or….does it have flowers?
-Nope, it has eggs and sperm just like us. Bladderwrack and narrow wrack have male and female plants and actually have an almost identical lifecycle to humans.
-It has eggs and sperm?! But…is it an animal, then?

Suddenly you realize that what you learned during biology class in school was just a rough cut, simplified picture of reality. Nature and evolution is so much more than that, with more imagination and concepts than we humans are able to name.

I think it is fantastic that algae, some of the planet’s first living organisms, have used eggs and sperm for a long time. Maybe longer even than humans have been around. A flick on the nose at us when we think we are evolutionarily advanced.

Here’s a video of how eggs from bladderwrack start spinning by all the sperm swimming around them, hoping to fertilize. Beautiful!


Narrow wrack (Fucus radicans) and bladderwrack (Fucus vesiculosus) have separate male and female plants. The reproductive organs are called receptacles and are placed at the tips of the plant. They are easily recognised by their warty structure.

When we try to “sow” seaweed”, we start with collecting ripe plants from the field, determine which sex they have, and cut of the receptacles.

Cut receptacles of bladderwrack

Cut receptacles of bladderwrack

The picture to the left shows a bladderwrack ready to sow. Note that the pile of cut receptacles to the right in the photo is from three plants.

In order to separate between males and females, one has to cut a mm-thin slice of the receptacle and (with a little magnifying help from a loupe or similar) see if there are oogonia (8 eggs in a small sack) or antheridia (64 sperm in an even smaller sack). This can only be done on ripe receptacles, or else it is very hard to see.

Round oogonia contains 8 eggcells. Some are beginning to open up.

Round oogonia contains 8 eggcells. Some are beginning to open up.

Each receptacle consists of several small chambers, conceptacles. The opening pore of these conceptacles are what causes the warty structure of the receptacle. Each conceptacle openes onto the receptacle surface, and this is where oogonia and antheridia (eggs and sperm in bags) are ejected out into the water mass during fertilization. When the oogonia and antheridia have reached the water, the bag keeping them contained, begins to dissolve.

The female oogonia looks like a collection of small green peas, and can be seen with the naked eye if they are very ripe.

It's a girl! Lots of ripe, round oogonia in the receptacles.

It’s a girl! Lots of ripe, round oogonia in the receptacles.

A ripe male, packed full of orange sperm.

A ripe male, packed full of orange sperm.

Antheridia are too small to see, even with a loupe. You need a microscope for them. On a receptacle cut, they give an impression of orange balls along the inside of the receptacle edge (see picture). The colour comes from the eyespot of the sperm, which is orange. With this, the sperm can tell light from dark.

Reproduction occurs around full moon, when it is much darker down towards the bottom than up towards the surface. The sperm “knows” that it should swim towards darkness. The reason for this is that the heavy eggs are sinking in order to attach to the bottom once they become fertilized.

Fucus radicans – Narrow wrack

The scientific name of narrow wrack is Fucus radicans which means that it belongs in the Fucus family, together with bladderwrack, serrated wrack and spiral wrack (Fucus spiralis).

Narrow wrack is recently discovered, since it was long belived to be a dwarf morph of bladderwrack. It is not unusual that organisms are smaller in the low salinities of the Baltic Sea. Using genetic tools, narrow wrack was identified as a new species in 2005. Since then, researchers at Stockholm and Gothenburg University have studied the ecology, reproduction and genetics of the narrow wrack.

Narrow wrack (right) is thinner and more bushy than bladderwrack (left)

Narrow wrack (right) is thinner and more bushy than bladderwrack (left)

Narrow wrack is found along the Swedish coast from Öregrund to Umeå, from around Vaasa area down to Poori/Björneborg on the Finnish coast and around the Estonian island Ösel/Saaremaa (see map under The Baltic Sea fact). Narrow wrack has not been found outside the baltic Sea, as far as we know.

Narrow wrack is clonal, wich means that it reproduces by fragmentation, but it also has sexual reproduction. The individuals that have formed by fragmentation, where small branches from the plant falls off, drift away and then reattach to a rock or boulder, all have the same genetic variation as their “mother” plant. There is one plant in particular that have been very successful along the Swedish coast, where almost 80% of all individuals are one clone.

Fucus vesiculosus – Bladderwrack

The most common wrack in the Baltic Sea is the bladderwrack, Fucus vesiculosus. Fucus is from the greek phykos, meaning seaweed. The species name vesiculosus refers to the gas filled bladders that are common in the species.
It is belived thet the bladderwrack has been present in the Baltic Sea for about 8000 years, from the period known as the Yoldia Sea. Bladderwrack and serrated wrack (Fucus serratus) are both marine species that have, more or less, adapted to the brackish waters of the Baltic Sea. The best adapted species is bladderwrack, that we can find all along the Swedish coast almost as far north as Umeå.

Bladderwrack can vary very much in shape and size, depending on whether it is living on rocks that are exposed to strong waves or living in sheltered bays. Where it is sheltered it can grow to over one metre in height, with broad thallus and plenty of bladders.
In exposed sites, the bladderwrack often lacks bladders so that the waves cannot tear it away. Both height as well as thallus width is much less on exposed sites.

Bladderwrack has the same lifecycle as humans. The plants are either male or female. They produce eggs and sperm in special organs, called receptacles. The receptacles are located in the tips, with a warty structure.


Eggs and sperm are released into the water column on still nights around full moon. The negatively buoyant eggs sink to the sea floor, followed by actively swimming sperm. New seaweed is made.