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  Sanctuary Integrated Monitoring Network
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Species Database

Pelvetiopsis limitata - Dwarf Rockweed

Dwarf Rockweed image

Geographic range:

Vancouver Island, British Columbia to San Luis Obispo County, California

Key features:

Like other rockweeds it has dichotomous branches and is olive green. It is smaller than similar species, only 8-15 cm long. No midrib on thallus.

Similar species:

Silvetia compressa -- Elongate clumps
Fucus gardneri -- Bladderwrack
Hesperophycus californicus -- Hairy rockweed

Habitat(s):

exposed rocky shore
 

Primary common name:

Dwarf Rockweed

Synonymous name(s):

Pelvetia fastigiata limitata

General grouping:

Brown seaweed/algae

ITIS code:

11354
 

Geographic Range

Range Description:

Pelvetiopsis limitata occurs from Vancouver Island, British Columbia to San Luis Obispo County, California.

Intertidal Height

Lowest intertidal height:

0 meters OR 0 feet

Highest intertidal height:

0 meters OR 0 feet

Intertidal height notes:

Pelvetiopsis limitata can be found in the high intertidal.

Subtidal Depth Range

Minimum depth:

0 meters OR 0 feet

Maximum depth:

0 meters OR 0 feet

Habitats

exposed rocky shore

Habitat notes:

Pelvetiopsis limitata lives on rocks in the high intertidal of exposed outer coast habitats. It thrives in regions subject to strong surf.

Abundance

Relative abundance:

Pelvetiopsis limitata is common in the high intertidal of exposed coasts.

Species Description

General description:

Pelvetiopsis limitata is a perennial brown Alga, division Phaeophyta, in the class Phaeophyceae, order Fucales and the family Fucaceae. It is named after the French botanist, Dr. Pelvet. Its common name, Dwarf Rockweed comes from how closely it resembles Rockweed, Fucus gardneri, but in a dwarfed form. Pelvetiopsis limitata is considered a good indicator organism of exposed rocky coasts. It maintains a high position in the intertidal region and forms extensive zones.

Distinctive features:

Pelvetiopsis limitata has an olive green to light tan thallus that arrises from a small discoid holdfast. The thallus is dichotomously branched, meaning it lacks a central axis and thus the branches lie mostly in one plane. The branches are cylindrical at the base becoming flattened to cylindrical in the upper fronds. They lack midribs and tend to arch inward. Mature branch tips develop warty inflated conceptacles in which the gamete producing organs lie. Male and female organs can be found on the same seaweed and each female organ produces a single, functional egg cell.

Pelvetiopsis limitata can at times be confused with Rockweed, Fucus gardneri, Hesperophycus californicus, and Silvetia compressa. Fucus gardneri and Hesperophycus californicus can be differentiated by their wider fronds with midribs since Pelvetiopsis limitata has narrower fronds and lacks a midrib. Silvetia compressa can grow to be much larger than Pelvetiopsis limitata and tends to have a more southern distribution.

Size:

Pelvetiopsis limitata can grow up to 15 cm tall.

Natural History

General natural history:

Pelvetiopsis limitata, like all photosynthetic organisms, contains the green pigment chlorophyll. They additionally also contain other gold and brown pigments which give all brown algae their coloration. The dominant pigment found in brown algae in called fucoxanthin and it reflects yellow light.

Predator(s):

Limpets and other invertebrate grazers feed on Pelvetiopsis limitata.

Prey:

Pelvetiopsis limitata nourishes itself through photosynthesis, converting the energy of light to the energy of carbohydrate molecules.

Feeding behavior

Photosynthetic

Click on an image below to view a larger version in the SIMoN Photo Library. You will also be able to view important information on each photo such as photographer, date, caption and more.
Abbott, I.A., and G.J. Hollenberg. 1976. Marine Algae of California. Stanford University Press, Stanford, California. 827 p.
MARINe. 2004 (Updated 12/09/04). Multi-Agency Rocky Intertidal Network. World Wide Web electronic publication, http://www.marine.gov, Accessed [04/22/06]
Meinkoth, N.A. 1998. National Audubon Society Field Guide to North American Seashore Creatures. A.A. Knopf, New York, NY. 813 p.
O'Clair, R.M. 2000. North Pacific Seaweeds. Plant Press, Auke Bay, Alaska. 162 p.
Waaland, R. 1977. Common Seaweeds of the Pacific Coast. Pacific Search Press, Seattle, Washington. 120 p.