Rocky Intertidal Species – Algae

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Identifying algae is not always easy! Learn more about the algae monitored by the LiMPETS program. The list below consists of 9 taxa that are monitored at all our sites.

Coralline Algae (Bossiella spp./ Calliarthron spp./Corallina spp. / many species)

Encrusting Coralline Algae
Description

Coralline algae comes in two forms: encrusting and upright.

There are many types of encrusting coralline algae, at least five genera and nine species are found along our coast. Species can be difficult to correctly identify in the field; their distinguishing characteristics are traits such as crust thickness, cell dimensions, and reproductive structures. All of the species are “crunchy” due to the calcium carbonate found in their cell walls. They range in color from grey to dull pink to bright pink.

Many species, often difficult to distinguish from one another. All of the species have calcium carbonate deposits in their cell walls, making them relatively stiff; many species are branched and have tiny jointed segments. Sometimes they persist without upright segments, in which case they are counted as Encrusting Coralline Algae. They are found in a variety of colors including grey, dull pink and bright pink.

Distribution
Alaska to Chile.
Habitat
Abundant on rocks and mollusk shells in the mid to low rocky intertidal and shallow subtidal; on rock faces and in tidepools.
Diet
Calcium and magnesium carbonate from the seawater as well as sunlight and dissolved nutrients, which are required for photosynthesis.
Fun Fact

It used to be thought that encrusting corallines were animals related to coral. In the tropics, they have an important role in building coral reefs.

Although the calcium carbonate in the tissues make it difficult for many animals to feed on these algae, there are a few molluscs, like lined chitons and dunce-cap limpets, that readily feed on them.

Reason for Monitoring

These algae are resistant to trampling and pollution, though sensitive to dessication (drying out due to air exposure). They are a dominant species on primary substrate.

Resistant to grazing, trampling, and pollution, especially Corallina spp., which sometimes are the main algae remaining around sewage discharges.

References

Mondragon, J and J. Mondragon. 2003. Seaweeds of the Pacific Coast: Common Marine Algae from Alaska to Baja California. Sea Challengers, Monterey,California.

Green Pin Cushion Alga (Cladophora columbiana)

Green Pin-Cushion Alga
Description

Green pin-cushion alga is bright green, spongy, and consists of branched filaments that form densely matted tufts. It resembles clumps of moss. This alga effectively holds water and can withstand long periods of exposure.

Distribution
British Columbia to Baja California.
Habitat
Common, on rocks, in the mid to high intertidal.
Diet
Sunlight and dissolved nutrients, which are required for photosynthesis.
Fun Fact

Competition for space in the intertidal is a factor for all organisms. This alga not only competes with other algae, it also competes for space with several marine invertebrates. In some cases, the seaweed effectively smothers sessile invertebrates such as mussels and barnacles by growing on top of them.

Reason for Monitoring

It is a high intertidal zone indicator.

References

Mondragon, J and J. Mondragon. 2003. Seaweeds of the Pacific Coast: Common Marine Algae from Alaska to Baja California. Sea Challengers, Monterey,California.

Monterey Bay Aquarium Research Institute: Marine Botany

Iridescent Algae (Mazzaella flaccida/splendens)

Iridescent Algae
Description

These algae are seen in a variety of colors including dark-purple, brown, green, bluish-purple, and may even appear black. They appear iridescent when underwater or when wet because of thin layer interference. The blades are relatively thin and vary in shape and size (up to 3 feet long and 10 inches wide) depending on the habitat and the amount of wave exposure.

Distribution
Alaska to northern Baja California.
Habitat
Abundant on rocks in the mid to low intertidal and upper subtidal. Found in both exposed and moderately sheltered habitats.
Diet
Sunlight and dissolved nutrients, which are required for photosynthesis.
Fun Fact

Iridescent algae are one source for carrageenan, a substance commonly used to thicken, stabilize or jell products such as toothpaste, ice cream and cosmetics.

Reason for Monitoring

They are a mid zone indicator, dominant competitor, and are potentially harvested for carrageenan.

References

Mondragon, J and J. Mondragon. 2003. Seaweeds of the Pacific Coast: Common Marine Algae from Alaska to Baja California. Sea Challengers, Monterey, California.

Rockweeds (Fucus gardneri / Hesperophycus californicus / Pelvetiopsis limitata / Silvetia compressa)

Flattened Rockweeds
Description

Olive green to brownish in color. They can reach 25-30 cm (1 foot) in length; have a small holdfast and flattened, dichotomously branched blades with a distinct midrib. The holdfast is leathery, conical, and relatively small. Mature branches will have swollen, warty receptacles at the tips. Some rockweeds have a thick outside layer that makes a sticky substance to help retain moisture.

Distribution
British Columbia to central Baja California.
Habitat
Common in the high to mid intertidal zone.
Diet
Sunlight and dissolved nutrients, which are required for photosynthesis.
Fun Fact

To discourage predation, rockweeds secrete a chemical that makes them hard to digest.

These algae are frequently exposed to air at low tide, and can photosynthesize both in and out of water. The fronds trap moisture and provide protection to barnacles, shore crabs, tubeworms and snails.

Reason for Monitoring

Sensitive to trampling; a high zone indicator.

References

Mondragon, J and J. Mondragon. 2003. Seaweeds of the Pacific Coast: Common Marine Algae from Alaska to Baja California. Sea Challengers, Monterey,California.

UCSC’s Pacific Rocky Intertidal Netowrk: Herperophycus (Olive rockweed)

UCSC’s Pacific Rocky Intertidal Monitoring: Pelvetiopsis (Dwarf Rockweed)

UCSC’s Pacific Rocky Intertidal Monitoring: Silvetia (Golden Rockweed)

 

Scouring Pad Alga (Endocladia muricata)

Scouring Pad Alga
Description

This is dense, bushy, stiff, profusely branched, and spine-covered algae. It forms dark-brown to reddish-brown clumps that grow to be 3-8 cm tall. For LiMPETS monitoring purposes, it is crucial to note that an extremely similar species,Caulacanthus ustulatus, can be confused with the native scouring pad alga, E. muricata. The best way to distinguish between the two species is to pinch off a piece and look at the axes: E. muricata has small spines along its axis and C. ustulatus does not. The axes of C. ustulatus are round and the tips are pointed. In addition, E. muricata is a dark red/brown color, while C. ustulatus is a lighter red. Learn to distinguish between these two species, before going into the field. C. ustulatus is a non-native, potentially invasive species that has the potential to displace E. muricata.

Distribution
Alaska to Baja California.
Habitat
Abundant in the high intertidal on tops or vertical faces of rocks and on mussels. The highly branched, bushy nature of this alga and the clumps that it forms enable it to retain moisture during low tide; allowing it to survive in the high intertidal.
Diet
Sunlight and dissolved nutrients, which are required for photosynthesis.
Fun Fact

This alga serves as a refuge for more than 90 species of animals, including snails, worms, mussel, and fly larvae and is usually found in association with small acorn barnacles, Balanus glandula and Chthamalus spp.; other common inhabitants of the high intertidal.

Reason for Monitoring

Sensitive to trampling and is a high and upper mid zone indicator.

References

Mondragon, J and J. Mondragon. 2003. Seaweeds of the Pacific Coast: Common Marine Algae from Alaska to Baja California. Sea Challengers, Monterey, California.

UCSC’s Pacific Rocky Intertidal Monitoring: Endocladia (Turfweed)

Sea Lettuces (Ulva spp.)

Sea Lettuces
Description

Sea lettuces are bright green, thin, tubular to broad, and often crumpled-looking algae. They are only two cells thick and almost transparent. They attach to rocks with a small holdfast, and can easily be torn away. Sea lettuces can form large blooms when nutrient levels are high and then bleach and die. Tubular forms,Enteromorpha spp., are now included among the species of Ulva.

Distribution
Worldwide; along the West Coast of North America, from Alaska to Mexico.
Habitat
Common in bays, lagoons, harbors, marshes, and open rocky coast; found in the intertidal and shallow subtidal.
Diet
Sunlight and dissolved nutrients, which are required for photosynthesis.
Fun Fact

These algae are commonly eaten; they are dried, toasted or eaten fresh in salads, soups and other dishes. Many species of Ulva are reported to be tolerant of organic and metal pollution; so if you eat these algae, make sure they are collected far from any potential sources of pollution.

Reason for Monitoring

Indicates high disturbance areas. After a disturbance, they are among the first algae to grow back and populate an area, before being grazed and replaced by other algae.

References

Mondragon, J and J. Mondragon. 2003. Seaweeds of the Pacific Coast: Common Marine Algae from Alaska to Baja California. Sea Challengers, Monterey, California.

Stunted Turkish Towel (Mastocarpus spp./Mazzaella affinis)

Description

These are common algae in the California intertidal. The two species of MastocarpusM. papillatus and M. jardinii, as well as Mazzaella affinis, are difficult to distinguish and are put in one category for monitoring. All three have small dark red to purplish-black blades that split near their ends; the blades can be narrow (1-2 cm) or wide (5-7 cm). The blades of both species of Mastocarpus often are covered with bumps (papillae); they have a complex life cycle with a crust phase that looks very different from the often bumpy blades of the upright phase. The crust phase is monitored separately as some of the many species of tar-spot algae.

 

Distribution
Alaska to Baja California.
Habitat
Abundant in mid to high rocky intertidal areas.
Diet
Sunlight and dissolved nutrients, which are required for photosynthesis.
Fun Fact

Before the life cycle was understood, phycologists thought that the crust phase of Mastocarpus spp. was a distinct species that was placed in a separate genus, Petrocelis.

Reason for Monitoring

They are common and abundant species in the high and mid zones of many of the LiMPETS sites, and are sensitive to trampling.

References

Mondragon, J and J. Mondragon. 2003. Seaweeds of the Pacific Coast: Common Marine Algae from Alaska to Baja California. Sea Challengers, Monterey, California.

Surfgrasses (Phyllospadix scouleri/torreyi)

Surfgrasses
Description

Surfgrasses are flowering plants, grassy green to bright green in color. The leaves are narrow (1-4 mm) and can be up to 2 m in length depending on the species. They provide an important habitat for algae and marine invertebrates.

Distribution
Alaska to Baja California.
Habitat
Usually found in the low intertidal and subtidally to 6m. Some species of surfgrass are usually found in protected sandy areas (P. torreyi), while others such as P. scouleri are usually attached to rocks in exposed areas. However, the two species can be extensively intermingled.
Diet
Sunlight and dissolved nutrients, which are required for photosynthesis.
Fun Fact

Native Americans along the West Coast harvested the seeds of surfgrasses for food. The seeds are high in caloric value and in protein.

Reason for Monitoring

Surfgrasses are a competitive dominant marking the upper limit of the low zone and are sensitive to pollution.

References

Mondragon, J and J. Mondragon. 2003. Seaweeds of the Pacific Coast: Common Marine Algae from Alaska to Baja California. Sea Challengers, Monterey,California.

UCSC’s Pacific Rocky Intertidal Monitoring: Phyllospadix (Surfgrass)

Tar Spot Algae (Mastocarpus spp./Ralfsia spp. and others)

Tar Spot Algae
Description

These algae are dark brown to black crusts that grow on rocks. They are smooth or have prominent radial and concentric ridges. There are many nearly indistinguishable crust forms of several species of red and brown algae. Species of Ralfsia (brown algae) are nearly indistinguishable from the sporophyte crust of Mastocarpus spp. (red algae), so they are counted together, along with other less abundant species of encrusting red and brown algae, as tar spot algae for the purpose of LiMPETS monitoring.

Distribution
Alaska to Mexico.
Habitat
Common on rocks throughout the intertidal.
Diet
Sunlight and dissolved nutrients, which are required for photosynthesis.
Fun Fact

At least one “species” of Ralfsia is a growth form of an upright, thin blade-like brown algal species, Petalonia fascia. Whether it is a crust or blade may depend on temperature and photoperiod; warm temperature and long day lengths lead to the crust form. On the other hand, the tar-spot forms of Mastocarpus spp. are separate parts of the life cycle of those species, which are monitored as Stunted Turkish Towel algae by LiMPETS.

Reason for Monitoring

These encrusting forms are resistant to grazing, trampling, and pollution and can be the dominant species on primary substrate.

References

Monterey Bay Aquarium Research Institute: Marine Botany

Abbott, I.A. and G.J. Hollenberg. 1976. Marine Algae of California. Stanford, University Press, Stanford, California.

We also monitor:

  • Bare rock
  • Loose sand
  • Tar (petroleum)