Monterey Bay Aquarium Research Institute
Marine Botany

Chondracanthus Drift 

Purpose/Procedure:  In order to gain a deeper understanding of the local distribution and abundance of Chondracanthus, I performed a short study of the drift at four local sites along Monterey Bay.   I measured the total amount of drift and percentage of this which was Chondracanthus at each site.   The study sites and results are given below, as well as an indication of the exposure level at each site.

Study Points on Monterey Bay:
map of Hopkins Marine Station
Exposure Scale (enlarged)


1-extremely exposed shore
2-very exposed shore
3-exposed shore
4-semi-exposed shore
5-fairly sheltered shore
6-sheltered shore
7-extremely sheltered shore

From: Julie M. Johnson. 1982.  175 H. Unpublished paper on file in HMS Library.   Species Distribution of Supralittoral Lichens on the Southern Shore of Monterey Bay. 

Data: graph of data  

Lucas Point
Total drift:    486.2 sq in per 3ft width
Percentage Chondracanthus: 48.6%
Exposure scale: very exposed (2)

Lover's Point
Total drift:    45.2 sq in per 3ft width
Percentage Chondracanthus: 26.1%
Exposure scale: exposed shore (3)

Hopkins-Agassiz Beach
Total drift:    102.2 sq in per 3 ft width
Percentage Chondracanthus: 45.0%
Exposure scale: fairly sheltered shore (5)

Cannery Row-San Carlos Beach                                                                    
Total drift:     98.2 sq in per 3ft width
Percentage Chondracanthus: 40.0%
Exposure scale: sheltered shore (6)                                                        

link to large habit shot (27375 bytes)Example of Drift at Site (Agassiz Beach)

Conclusions:    The results from this brief study are easily represented on the chart.   First, there were obvious discrepancies between the total amounts of drift at the four sites.  I had suspected that drift might vary with exposure level: the more exposed the beach, the more drift it would have.  This held true somewhat, except for the drift data from Lover's Point Beach.   Further exploration yielded additional data that this beach apparently is often cleaned for tourist use, which would obviously decrease the amount of drift and make this area of the study less precise.  However, the data on Chondracanthus percentage of drift at each site remains valid.  On average, about 40% of the total drift was Chondracanthus, indicating that this species is quite abundant, and individual percentages at each site were relatively consistent, indicating that the species is also widely distributed locally.

Suggested Further Study:  There are obviously many ways which I would like to extend this study if time allowed.   Some suggestions for further study include:

  • Distribution/Abundance around Monterey Bay:  This would involve a similar procedure applied over a much wider range of study sites, covering the entire Monterey Bay shoreline.   This data would expand the picture of Chondracanthus distribution in the local area, as well as hopefully provide enough data to analyze the effect of exposure level on Chondracanthus distribution as well as total amount of drift.
  • Subtidal Transect:  This would involve actually looking at the immediate surroundings of C. exasperatus subtidally.  Within the structure of a transect, the associated flora and fauna could

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Last modified: 3/18/99
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