Monterey Bay Aquarium Research Institute
Marine Botany

Delesseria decipiens Ecology

Ecology | Morphology | Glossary | Acknowledgments

Delesseria in hand
Delesseria decipiens
growing on a buoy line, March 4, 2003

Distribution Delesseria decipiens lives in low intertidal to subtidal areas on the west coast of North America, from Alaska to San Luis Obispo, CA. D. decipiens is Map of Montereysaxicolus, meaning that it grows on rocks and can be found on the vertical faces of rocks in the low intertidal areas. D. decipiens was first collected in 1859 in the Straits de Juan de Fuca, near present day Washington State. Samples of D. decipiens were found in the Hopkins Marine Life Refuge growing on buoy lines in late January and early March. Data collected from the Gilbert M. Smith Herbarium also indicates that D. decipiens grows in a wide variety of locations around the Monterey and Carmel Bay areas. Locations of D. decipiens in the past have included, from north to south, Point Pinos, Moss Beach, Asilomar, Spanish Bay, Point Joe, Cypress Point, Pescadero Point, Pebble Beach, Stillwater Cove, Carmel Beach, Mission Point and Soberanes Point. Herbarium notes suggest that D. decipiens can grow in a tidal range form 0.5 to -1.5 feet, although some sources indicate that it grows at depths of 20 feet. Map of coastline of the Monterey Peninsula.
from Abbott and Hollenberg. Marine Algae of California. Stanford University Press, Stanford: 1976

To see additional data from the G.M. Smith Herbarium Click Here

Seasonal Growth Delesseria decipiens is a spring annual that can be found in the Monterey Bay region from late January to July. Based on a survey of D. decipiens samples in the Gilbert M. Smith Herbarium, plants seem to reach their maximum size, as measured by the length of their primary midrib, in May and June. There did not appear to be any pattern of reproductive development with samples becoming reproductively identifiable in April and continuing through July.
     While the seasonal growth patterns in D. decipiens has not been studied in depth, similar studies have been made on the seasonal growth patterns of Delesseria sanguinea, a sub-littoral alga that inhabits European coasts in the North Atlantic. While D. sanguinea is closely related to D. decipiens, it is an annual plant, not a perennial plant like D. decipiens so the growth patterns of the two cannot be directly correlated. D. sanguinea does exhibit similar spring growth patterns, however, making it a valuable comparison. D. sanguinea shows growth of new blades beginning in the winter and continuing through the spring and early summer. Blade initiation is induced by water temperatures bellow 13° C, and optimal growing temperatures are between 10 and 20°C. Blade degradation begins in the summer and continues through the fall. Reproduction is under photoperiodic control, with the algae needing short days of less than 13 hours in order to stimulate development of reproductive structures. This ensures that the gametophytes develop simultaneously allowing successful fertilization to occur more often. Reproduction occurs in the late fall. While D. sanguinea has some major differences in its seasonal life history, a comparison between the two algae is valuable in providing information about general characteristics of the genus and suggesting possible areas of research when studying D. decipiens.

Sensing UV Light Studies done in Delesseria sanguinea have shown that D. sanguinea is a sensitive and reliable indicator of UVB light, demonstrating a significant reduction in growth rates when compared to exposure to visible sunlight and UVA light alone. This is significant as continued thinning of the ozone layer allows more UVB light to reach the earths surface. UVB is a highly destructive form of UV light and accurate indicators such as D. sanguinea could be highly valuable in monitoring the effects of UVB levels on biological life. It is not currently know whether D. decipiens shares the same UVB sensitive properties, but testing this property could be an area of further research.

nudibranchDelesseria decipiens as a habitat Delesseria decipiens can act as a habitat for other invertebrates and marine organisms. In a sample collected on March 4, 2004 from a buoy line several invertebrates were found in association with D. decipiens. These invertebrates included several caprellids, called skeleton shrimp (Phylum Arthropoda, Class Crustacea, Order Amphipoda), a tiny nudibranch (above right) Coryphella trilineata (Phylum Mollusca, Class Gastropoda, Order Nudibranch), several acorn barnacles of the genus Lepas (Phylum Arthropoda, Class Crustacea. Order Thoracica), and an unidentified worm from the phylum Nemertea about 2mm long. wormbarnacle


Nemertean worm
magnification 100 times (left)



Gooseneck barnacle living on Delesseria decipiens (right)



Caprellid shrimp attached to algae

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© Hannah Griego 2003