Monterey Bay Aquarium Research Institute
Marine Botany

Chondracanthus Distribution and Ecology  

Geographical Distribution

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Gigartinaceae: Worldwide Distribution
 
Key:
C-Chondrus                M-Mazzaella
I-Iridaea                      S-Sarcothalia
R-Rhodoglossum      X-Chondrocanthus
G-Gigartina

This map shows the distribution of the Gigartinaceae by genus.   While it did not reproduce extremely well, the X's (Chondracanthus) can fairly easily be distinguished, indicating its worldwide distribution (Hommersand et. al., 1993).

Chondracanthus exasperatus: Worldwide Distribution

    The range of C. exasperatus extends from Vancouver, British Columbia to Maria, Baja California. Three varieties of this species have been identified over this range.  In the northern reaches of its range, specimens have extremely irregular edges. Central californian specimens have very thick blades and are often found in close proximity, even overlapping with other specimens, as opposed to southern specimens which are more widely spaced.
 
               Northern variety                          Central/Southern variety
                                        

Other varieties of C. exasperatus

                          


  Vertical Distribution and Ecology

C. exasperatus: Vertical Distribution:  C. exasperatus is found on rocks in the lower intertidal and subtidal zones.   Typical depth ranges from 5-10m.

Light availability: Because C. exasperatus is commonly found at these lower depths, it is exposed to lower light intensities than many intertidal algae.   Furthermore, it is often associated with kelp forests, which block much of the available light.  C. exasperatus is able to continue active photosynthesis in this low light, sheltered environment because its accessory pigments are specialized to absorb this filtered light.  Mumford and Waaland have found that maximum growth rate occurs at 3m below the M.L.L.W. (mean low low water) and the maximum growth season is between March and September (Mumford and Waaland, 1980).

Space availability:  The limiting factor to C. exasperatus abundance is usually the amount and distribution of suitable substrate.

Algae associated with the vertical range of C. exasperatus:

   (Hommersand et. al., 1993)

    General algal community known as the kelp forest community. This community is divided into four levels, the canopy species (ie. giant kelp, bull kelp), the understory species (such as the lesser kelps), the turf species (including many reds such as sea grapes), and the crust species (such as coralline algaes).  C. exasperatus is a turf species. Basic kelp forest ecology makes certain predictions for the competitive ability and resistance to damage by storms of turf species. Briefly, competitive ability (mostly for light) is hierarchical, moving up from the crust species to the canopy species, as explained earlier in the light availability section.  There is an opposite hierarchy for resistance to damage from storms, turf and crust species being more resistant than understory and canopy species (Watanabe, 1998).


Epiphytes
  Some algae choose to solve the problem of limited space by epiphtism. C. exasperatus is a common anchor species, or basiphytes, for epiphytes. While this unique solution benefits the epiphyte, basiphytes, such as C. exasperatus, often suffer negative effects due to shading, impeded gas and nutrient exchange, and increase drag on the blades all because of the epiphyte. Some algae do have chemical or physiological mechanisms to inhibit epiphyte growth, and whether C. exasperatus has any of these is unknown, though it seems unlikely as a large number of specimens I collected had epiphytes growing on them.

Animals associated with the vertical range of C. exasperatus:
    Listing the animals associated with the lower intertidal rock habitat, where C. exasperatus, is most commonly found, is an immense task because this area is the most prolific of the intertidal habitats.  Some of the most abundant animals include seastars, urchins, tube worms, snails and tunicates. Of these snails, such as Tegula, have been found to be the major herbivores of large, foliose algae such as C. exasperatus (Ricketts et al., 1985).  However, investigations of snails roles in the growth of cultivated C. exasperatus have shown that their overall effect is positive, especially at the germling stage. The young algae typically grows fast enough to perturb direct herbivory. Instead, the snails feed on diatoms, which would otherwise foul the settlement and growth of the young germlings.

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Last modified: 3/18/99
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