Heterosiphonia japonicaFOUND by RedRiots
Quality checked by 18 students in Marine Biology and a teacher
Peer reviewed by 18 students in Marine Biology and a teacher
Our Marine Biology class went to Crescent Beach on a grey, but mild morning in search of at least twelve different species of seaweeds. We are studying macroalgae and getting to know the local seaweeds. We limited our search to specimens that had washed up on the beach, in order to minimize disturbances to intertidal communities. Since we collected drift seaweed, we cannot determine exactly where these algae were growing. We know that seaweeds need a surface for attachment. Since our species were not bleached, we thought they got torn off of the surrounding ledges during some recent rough seas. We were wondering if we might find some southern species due to the warm ocean temperatures we experienced this summer and into the fall. We collected red, brown, and green samples, some familiar and some unknown, which we brought back to the classroom to press and identify.
We examined the cells of our specimen and found that the main axis had rows of rectangular cells, similar to Polysiphonia, but the side branches were one-cell thick. We haven't seen this in any of the Polysiphonia species that we know. The main axis, or branch, seems to be 3-4 cells wide in our specimens. These cells do not seem as narrow as those found in Seirospora, although their size varied a bit among our specimens.
The clusters of branches made us question whether or not this was a native species. None of the other reds in our local guides showed two branches curving inward with many smaller, seemingly newer branches inside. We saw this again and again at various stages of growth, some just starting to appear. We noticed that the shape of the cells changed towards the tip of some branches, too. The branch in the upper-right side of the photo shows an example of this. We even found a pointed, banded tip, called an apex in some red species, that might be the early stages of these circular cells. Seirospora interrupta, in its reproductive state, possesses seirospores in rows, and photos on algaebase.org show both rectangular and circular cells on S. interrupta. S. interrupta is uncommon north of Cape Cod and is often found in warm bays and estuaries. Since the water off of Crescent beach was so warm this summer, we kept focusing on S. interrupta and other local reds, but none showed the branching clusters that we saw repeatedly on our seaweed. We examined photos of Heterosiphonia on alagebase and they included specimens with very similar growth patterns.
Many of us were drawn to this species by its bright red, almost pink, color. This seaweed is soft and delicate, not stiff and wiry like some reds. Once we read reports of this species in Cape Elizabeth, we began to examine more images online, since none of our guides included Heterosiphonia. This is an invasive species that has taken over regions in other parts of New England. This concerns us, since we found multiple specimens. We've been able to collect addition samples on return trips to Crescent beach, indicating that there might be an abundance of this species growing here. Ten out of seventeen students found this species during our trip to Crescent Beach. Other students may have the species, but they opted not to identify it for their project.
N 43.563669 °
W -70.219614 °
Fri, 2012-10-19 07:40
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Fri, 2012-10-19 08:12