Fucus radicans

by

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!

by

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.

by

The Baltic Sea

The Baltic Sea is unique because of its low salinity. In the northernmost parts, the water is almost considered freshwater, whilst the salinity at the entrance/exit in Öresund lies around 15 psu (practical salinity unit, roughly equal to ‰ and denotes salinity). The low salinity of the Baltic Sea makes it a stressful environment for both freshwater and marine species, both groups lives on the very edge of their tolerance of either too high or too low salinity.

Salinity and Fucus distribution in the Baltic Sea

Salinity and Fucus distribution in the Baltic Sea

The map show surface water salinity and the distribution of the three species from the genus Fucus that can be found in the baltic Sea.
Green denotes bladderwrack (Fucus vesiculosus)
Orange denotes narrow wrack (Fucus radicans)
Yellow denotes serrated wrack (Fucus serratus) Note that for this species only the distribution along the Swedish coasline is shown, since we have not found any data on its distribution in any other countries along the Baltic Sea.

More information will follow.