Saltö

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Algae species of the month – February

For February, our Algae species of the Month will be two closely related species of brown algae, both of which belong to the family Scytosiphonaceae.
The first species is Petalonia fascia, also known by the common names Sea Petals or Broad Leaf Weed. It is a marine species that is not able to live in low brackish salinity, so it does not occur inside the Baltic Sea. It is, however, common along the coast of the North Sea and along the Swedish west coast. I found these specimens all dried up on one of the plastic containers that were sent ashore by the storm Urd, on a beach near the Tjärnö Marine biological station at Stromstad. So, in order to investigate what alga species it was that had settled on the container , I carefully removed the thin brown-green flat membranes that were attached to the plastic with only a tiny attachment-disc. The name Petalonia fascia reveals a lot about how the algae looks. Petal means leaf and fascia means ribbon in Italian.

The other marine species is Scytosiphon lomentaria,  known as Leather Tube or Chipolata Weed, and is just as Petalonia fascia a species that you can find during the cold season. It can form a belt just below the surface in the outer archipelago on the Swedish west coast in early spring and early summer. It is becoming more rare in the southern Baltic Sea and northwards from the Danish sound up to the Southern Quark, where the salinity is too low for it to survive. The ribbon-like thalli are yellow-brown and can be up to 25 cm long and 1-2 cm wide. They are hollow and have repeated “laced” narrow parts, making them look like a string of sausages, which gave the species its Swedish name, Sausagestring (Korvsnöre).  Scytos  means skin in Greek,  siphon  means pipes or tubes and  lomentaria  means lacing in Latin. So with a little knowledge of the ancient classical languages , the Latin name will provide you with information on how the algae looks.

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Both species have a complex life cycle. It is only the major strands of Scytosiphon lomentaria or leaf-shaped pieces of Petalonia fascia that are visible to the naked eye and are found in early spring to early summer. These are the sexual stage of the algae lifecycle, called gametophyte. They grow from a small, millimeter-sized disc with which the algae is attached to the substrate. These small discs are all that is left for the rest of the year, and they form the second stage of the lifecycle, known as the sporophyte.

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It is not possible to tell if the small brown spots or membranes you can see on a rock are sporophytes, which will grow in the spring so that the stone is covered by long sausage strings. Just wait and see. Maybe it’s some completely different species that emerges from all the microscopic stages that overwinter on the rocks and shells in anticipation of the return of light and warmth.  And for the ice to melt. However, it is amazing how much  freezing and dehydration the species living in the littoral zone can withstand.

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To determine what species I found dried-up on the red plastic container from Ireland was easy. I just had to put the dry seaweed in a little water on a plate so it was possible to take a photo. You have to take what you can find in order to get a good background. Once re-hydrated, then it was easy to recognize that it was Petalonia fascia, because this is a species I have found before on the Swedish west coast. Also, I found some blue mussel and small saddle oyster-shells  which made for a nice image.

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On a plate is where both Petalonia fascia and the closely related species Scytosiphon lomentaria really belong! Were you to visit Japan or other countries where it is common to eat different algae, you will find them dried and for sale under many different names; Kayamo-nori, Hime-kayamo, Ito-kayamo, Mugiwara-nori, Sugara, Yore- kayamo. I am not sure, but maybe they can be purchased at stores specializing in Asian products in Sweden too. Both species are known for their content of antioxidants. Otherwise, you can find your own little “Kayamo-nori” in the spring. It’s fine to eat just as it is. Just make sure they are picked far from discharges of polluted waters and not inside the marina.
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The wrack wall and how storms can tear seaweed from their rocks.

In the last posts, Lena has been reporting on all the interesting finds you can make on the beach after a storm. However, these haven’t been all that much about the different species of seaweed that gets washed ashore during strong winds. So, here is a small exposé of what she found after the storm Sven (Bodil in Denmark, Xaver in Germany).

In some bays on the west coast at Tjärnö, seaweed forms large beach walls whereas in other bays you will only find a few specimens of what is growing just a couple of meters off shore. Seaweed can also come entangled in ropes and lines from far away.
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A photo from a bay filled with seaweed forming thick carpets. Later in the year, in the summertime, they will have been decomposed and form a beach wall covered in lush green plants. Seaweed and algae make excellent compost due and was formerly gathered to fertilize the potato patches. If you find a bay full of seaweed you can collect some and put in your garden.
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On other shores, like in this photo, there is only some seaweed and the red alga Furcellaria lumbricalis in a band just by the water. This is the popular sandy beach at Saltö.
Higher up on the shore some distance away, i found a pile of rope and entangled algae. On closer examination, it turned out to be seaweed from quite some distance, maybe as far away as England.

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How can you tell that the seaweed is from far away and not just from next bay or further down the coast? If you look closely at the photo underneath, you’ll see some long, brown slightly knobbly bands, which are the reproductive organs (receptacles) of Himentalia elongata, which has never been found attached in Swedish waters. The nearest site is in Norway. In the pile there is also very large bladders of Ascophyllum nodosum and a form of bladderwrack (Fucus vesiculosus)with several bladders that is much more common in areas of higher salinity that at the Swedish coast.
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Those of you who look closely on the photograph will notice a red algae on the bottom right, like small, finely branched bushes attached to the Ascophyllum nodosum. This is one of many Polysiphonia species, and this particular species is commonly found growing on Ascophyllum nodosum and it is called Polysiphonia lanosa.
The wrack wall consists, as one might guess, mostly of wracks that have been washed ashore, both bladderwrack and serrated wrack (Fucus serratus). The smaller specimens were still attached to blue mussels (Mytilus edulis)and others had not attached hard enough to rock or boulder and had come loose.

Different sizes of wrack washed ashore, with accessories.

Different sizes of wrack washed ashore, with accessories.

Slightly larger specimens were washed ashore still attached to pebbles. A larger plant of seaweed is very firmly attached to the rock surface and you can lift the rock by holding the seaweed sometimes. It’s not until the wracks get really big that the pull of the wave manages to tear them loose from the rock or boulder to which they are attached. But, if you look closely on the bottom of the holdfast, there is a white calcareous layer. The wrack that has come loose with holdfast has once settled as a small germling on a crustose calcareous algae or a barnacle. So what has actually come loose by the wave force is not the seaweed holdfast, but the barnacle or calcareous alga that can no longer hold on to the rock surface.

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The photo shows a holdfast from a Fucus serratus with clearly visible white parts of a calcareous crustose alga.
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And finally – a somewhat late toast for the new year and wishing you all a happy 2014 from the BalticSeaWeed blog.

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Findings on the beach after the storm St Jude, 28th November

Storms are usually named in alphabetical order from the area where they begin. St. Jude was named in England but was re-named by SMHI (Swedish Meteorological and Hydrological Institute) to Simone after the name of the day in the calendar (in Sweden, each day of the year has one or two names) that the storm reached the Swedish west coast. The weather was less severe than expected at Tjärnö, but still quite strong winds and high water levels. I could still see the traces of this a month later, as we took a walk around Saltö.

The clear evidence of how high the water has reached during the last storm can be detected by looking at the size of the beach cast wrack border, and how far up on the beach it is.

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This picture shows three clear rows of wrack borders where algae and eelgrass has been gathered by water movements.

During the storm Simone, a lot of algae was washed high up on shore. The material in the wrack border tells us that the entangled algae and some mussel shells were torn away from quite deep locations. Among the species of mussels that I found in the wrack border was the horse mussel (Modiolus moduolus) which looks a bit like the common blue mussel (Mytilus edulis) but is larger and lives at greater depth.

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So, how do I tell a Modiolus moduolus from a Mytilus edulis? If you look closely at the picture, you’ll see that the pointy part (the umbo) is not at the tip of the shell as it is on the Mytilus edulis?, but slightly higher up on the shell. The shell of the Modiolus moduolus is also slightly browner than that of the Mytilus edulis, which is typically blue, as the common name denotes.

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Other traces on the beach shows that part of the beach cast comes from Norway or even as faraway as from the British Isles, and has been transported all this way before ending up in this tangle of seaweed on Saltö. I found Ascophyllum nodosum, which also grows on the rocky shores around Saltö, but these specimens had much larger vesicles (floating bladders)than the ones at Saltö and were entangled together with reproductive parts of Himenthalia elongata, an algae species that is sometimes referred to as “sea spaghetti”.

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Amongst our other exciting finds were several unusually large cuttlefish skeletons. It looked like they had been floating for quite some time in the sea, as they had a lot of green algae growing on them. They are often used as a source of calcium for caged birds. In days of old they were called “whale fish scales”, which is a double fault since the whale is not a fish and hence does not have scales.

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There were also remnants of the summer’s fun and games. The lost bucket for catching crabs and a deflated ball. Or the almost ghostly rubber gloves in a bucket of frozen water, which looked like an art installation.

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It was a cold but sunny day in November that we made all these discoveries at Saltö, which is part of the Kosterhavet marine national park near the Tjärnö Marine Laboratory. It will be exciting to come back around the New Year and see what coming storms have brought us, and if the bucket with gloves or the ball are still there. Maybe there will be some new species of seaweed from a faraway place, brought here attached to a floating shoe, a log or some other flotsam.