IB 362
Lecture 16
Seaweeds, algae, marine grasses
Algae – a diversity of protist organisms, the most conspicuous
of which are called seaweeds
Others can be single celled, or they can form an encrusting layer
on rocks
Seaweeds – actually are PROTISTS but are colonial and look plantlike
FIG. 12.1 Some of the diversity of form of seaweeds: (a) the green seaweed Ulva (ca. 25 cm high), (b) the green seaweed Codium fragile (ca.
30 cm high), (c) the red coralline alga Corallina (ca. 1 cm tall), (d) the red seaweed Polysiphonia (ca. 25 cm high), and (e) the brown seaweed
Laminaria (ca. 2 m long).
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
Green seaweeds (Chlorophyta)
Sea lettuce (Ulva)
Codium (invasive via oyster culture)
Brown seaweeds (Phaeophyta)
especially kelps (Laminaria and Macrocystis)
Fucus (intertidal)
Sargasso weed
Red seaweeds (Rhodophyta)
Ulva
(sea lettuce)
FIG. 12.6 The green seaweed Codium fragile, attached to a stack of the snail
Crepidula fornicata, and stranded on a beach on Long Island, New York.
(Photograph by Jeffrey Levinton.)
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
FIG. 12.2 The intertidal brown seaweed Fucus gardneri often completely
dominates protected rocky shores of the Pacific coast of the United States
and Canada. (Photograph by Jeffrey Levinton.)
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
FIG. 15.1 A bed of Zostera marina in Padilla Bay, Washington. Blades of this
sea grass are 50–100 cm high. (Photograph courtesy of Charles Simenstad.)
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
FIG. 15.8 A kelp forest in the Aleutian Islands: Cymathere triplicata
(foreground); Alaria fistulosa (rear). (Courtesy of David Duggins.)
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
FIG. 15.18 Succession in an Alaskan kelp forest.
Eventually (bottom) the kelp Laminaria
groenlandica dominated the forest and prevented
taller species from reinvading by shading out
juveniles. (Courtesy of David Duggins.)
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
FIG. 15.14 Two alternative stable states in kelp forests. (a) Luxuriant
kelp growth, with urchins that are sedentary and trap drift algae on
the dorsal surface. (b) A storm has stripped the kelps, and urchins
rove about the bed, denuding the bottom of all potential new
recruiting kelps.
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
Some commercially important seaweeds
Ulva – sea lettuce (can be eaten fresh in salads
Purple laver (Porphyra)– boiled and made into cakes in UK,
or cooked as a vegetable
Dulse (Rhodymenia) – used in cooking
Irish moss (Chondrus) – used in cooking
(carageenin – emulsifier – esp. dairy products)
Kelps (especially Japan) – called kombu, wakame
(also for algin, used as a stabilizer and emulsifier)
Nori (Porphyra) – used to make sushi (and also in soups)
Sea grasses – actually ARE flowering plants – can be
dominant organisms in some area, not only as primary
producers but as stabilizers of sediment and also
providers of cover for small (especially juvenile) animals
Pollen transported by water
FIG. 12.8 The surf grass Phyllospadix sp. on the outer
coast of British Columbia. (Photograph by Jeffrey
Levinton.)
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
FIG. 12.9 A turtle grass (Thalassia testudinum) bed,
Florida. (Photo by Jeffrey Levinton.)
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
FIG. 15.3 The scallop Argopecten irradians lives as a juvenile
attached to eelgrass blades, which reduces predation by crabs.
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
FIG. 12.10 Pollen release by sea grass, Zostera marina.
(Photo by Paul Cox.)
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.
FIG. 15.2 Scheme of succession from bare sand to a Thalassia testudinum sea grass bed in coastal Florida
waters. (Courtesy of Susan Williams.)
Marine Biology: Function,
Biodiversity, Ecology, 3/e
Levinton
Copyright ©
2009 by Oxford University Press, Inc.