Ulvaria sp.
Ulvaria obscura and cross-section (right) showing one cell layer.
Green Seaweeds | 65
Identifying Pacific Seaweeds
the field. Kornmannia blades remain small (to 5 cm/2 in) and are typically found growing on seagrasses and other seaweeds, with K. leptoderma smaller than Ulvaria and Monostroma, and not turning dark upon drying. A definitive field identification of Monostroma is beyond the reach of mere mortals.
Dopamine, an adrenaline-like compound, is another exotic chemical found in Ulvaria. Could this sea lettuce give a person an adrenaline rush?
Our understanding of the relationships among these local bladed forms is largely the result of the efforts of Maurice Dube (Western Washington University). Dube had a green (seaweed) thumb and cultured these plants through their young, informative stages. He died suddenly when accident-ally struck by a cyclist. The following poem was read at the Fourth North-west Algal Symposium, March 1989, in his memory.
Maurice Dube you accidentally died in your sixtieth year,
While walking a darkened street near your home.
In that very special early morning light,
With a tea-quickened pulse and a little stiff,
You and your students greeted many a low tide,
Heralded by the forceful slap of waves.
A multitude of seaweed forms lie exposed,
Accessible to you and your students.
And a glimpse assures the essential presence of your
Rich green undulant Monostroma.
Maurice, when the pale, cold, waxing moon
Draws back the watery curtain of tide,
We will join you on those compelling shores,
And once again share the marine wonderment.
—Louis Druehl
Habitat & Distribution
Ulvaria is distributed from Alaska to northern California, and various Monos-troma species are distributed from Alaska to southern California. Kornman-nia grows attached to seagrasses and other seaweeds from Alaska to central California.
66 | Cylinders
Pacific Seaweeds
Cylinders
Ulva (cylindrical form) Green string lettuce
Class Ulvophyceae Order Ulvales Family Ulvaceae
Number of Species
Ulva (Latin=marsh plant) contains a stunning 128 species and forms world-wide. Locally, it is represented by about 15 species, of which at least 7 develop a cylindrical morphology and were formerly contained in the genus Entero-morpha (Greek=intestine form). Common species in our area include: U. compressa, U. linza and U. intestinalis.
Description
Tubular species of Ulva (see p. 62 for discussion of bladed forms) have two cell layers that are separated to form a tube, like a cylindrical balloon. Ulva intestinalis is usually unbranched and cylindrical throughout, whereas U. compressa is often sparsely branched and imperfectly compressed away from the base. The tubes may reach 50 cm (20 in) in length but are usually less than 20 cm (8 in) long, and their width varies from a few millimetres to 4–5 cm (1.6–2 in). Ulva linza is tubular only at the base and looks similar to a bladed Ulva (or a deflated balloon), except that it is long, up to 45 cm (18 in), narrow, 1–4 cm (0.4–1.6 in), and distinctly ruffled.
A shaggy wig of cylindrical Ulva sp. adorns an intertidal rock.
Green Seaweeds | 67
Identifying Pacific Seaweeds
Several studies by Japanese and Italian researchers have shown that a seaweed’s morphology may be dependent on certain epiphytic marine bacteria. When grown in aseptic (free from bacteria) cultures, Ulva and other green seaweeds lose their natural leafy morphology and grow instead into a loose collection of cells. If grown with bac-teria, or even just a certain chemical isolated from bac-teria, the seaweeds develop as normal. These fascinating studies give a glimpse into the chemical communica-tion between seaweeds and micro-organisms in their environment that we have yet to fully understand.
Habitat & Distribution
Tubular Ulva are distributed throughout the intertidal zone, from Alaska to Mexico. Ulva intestinalis is the most common species and is cosmopolitan, being found growing on rock on all continents. It is often associated with freshwater seepages above the high tide level and in high tide pools, which through evaporation become salty to the point of producing crystalline salt. Ulva compressa often grows on other seaweeds and is not associated with fresh water. Ulva linza grows on rock or cobble in the mid- to low intertidal region.
A collection of short, individual Ulva sp. cylinders creates a carpet atop a rock.
Ulva intestinalis and cross-section (left) showing tubular nature of the plant.
68 | Spongy texture
Pacific Seaweeds
Spongy texture
Codium Sea staghorn, green spongy cushion
Class Bryopsidophyceae Order Bryopsidales Family Codiaceae
Number of Species
Of the whopping 143 known species and forms of Codium (Greek=animal skin), 3 are found locally: C. fragile, C. setchellii and C. ritteri.
Description
Codium is a conspicuous seaweed, spongy in texture and very dark green. Two basic morphol-ogies exist: branched