Monterey Bay Aquarium Research Institute
Marine Botany

Botryoglossum Ecology

Morphology      Ecology     Life History     Taxonomy     Reproduction  

Botryoglossum is represented on the West Coast by two species, B. farlowianum and B. ruprechtianum. The ranges of the two are fairly similar, and they often grow in the same places, making identification sometimes a bit confusing. To see a comparison of the two, click here . If you'd like to see what others algae are confusing you, check out the brewing taxonomic controversy

B. farlowianum is a versatile and far-ranging alga. It just dips into Mexican waters and extends its long red tongue along the coast into mid-British Columbia.

B. farlowianum is primarily subtidal, although it can be found on low intertidal rocks all along the coast north of Point Conception. Because of its propensity to dry out quickly, growing higher in the intertidal would be almost suicidal for the alga. Even in the lower subtidal, during very low "spring tides", the alga is in danger of drying out, as in the picture below. 

The Botryglossum above is exposed to the sun during a very low spring tide. The white color of the thalli shows the bleaching that occurs during sunlight exposure. To learn more about the role of  pigments, click here .

In the intertidal, this beautiful red alga plays the role of what is called "obligate understory algae." This means that it requires some protection from the surf and light by either a canopy layer or some other physical barrier in order to habitate the intertidal. B. farlowianum can occur intertidally in wide ranges of surf activity as long as there is considerable protection provided. 

Though intertidal, it is far more common in the subtidal. It uses its irregularly small holdfast to attach mainly to rocks, although it is also found growing epiphitically on other algae.

 Botryoglossum growing on an articulated coralline.

As part of the larger community, Botryoglossum plays a very versatile role. As well as being an epiphyte, it also plays host to many epiphytes. Among them are crustose corallines and the parasitic alga Gonimophyllum skottsbergii. If you look at the lower portions of the alga, you will often find G. skottsbergii growing in clumps of pink to greenish blades, in a fashion loosely resembling the marginal proliferations of Botryoglossum. If this resemblance plays any protective role for the parasite, it is not known.

Other animals live on and in the holdfast of Botryoglossum. Snails, such as Littorina and small Tegula, can be found roaming around on the blades and stipe. Whether these herbivores make a meal out of the alga is questionable. I have rarely seen any sort of holes on the algae which seem to have been made by grazing. Small animals, such as copepods, are sometimes found within the holdfast, perhaps hiding, perhaps having been caught there.

The community surrounding Botryoglossum varies in its make-up and abundance of Botryoglossum itself. While snorkeling for data, I personally observed areas of great abundance and whole regions mostly barren of Botryoglossum. B. farlowianum enjoys areas with good wave motion. This is attested to by its high population density lying dead on the beach. I observed that Botryoglossum tends to grow along the sides of rocks, especially in channels between rocks, in the subtidal. Perhaps this partially hidden area provides some protection from the surge in areas where there is no plant canopy.

In order to test Botryoglossum's ability to withstand breakage in rough surf, I conducted a biomechanical experiment. I tested the amount of strain which the central basal thallus could take before breakage occurred. The results are below.

 

Stress refers to the amount of pull imposed on the alga. Strain refers to how far the alga was stretched by  the machine.

If you'd like to see pictures of the experiment being conducted, click here .

The graph shows that B. farlowianum only made it through two stretch cycles, or one elongation of strain distance, before breaking. The evidenced inability of the strongest part of the plant to withstand much stress attests to its obligatory understory nature. The reasons for inhabiting rough areas must be good to live in such a risky place. Perhaps the rough surf helps to move the non-motile spermatia around, increasing chances of fertilization. Or perhaps the breakage of the algae plays some other role in its overall life history that had not yet been made clear.

Morphology      Ecology     Life History     Taxonomy     Reproduction

© 2001 Shasta Daisy Pistey-Lyhne . All rights reserved.  

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