Irish Moss Photo Gallery

Irish moss (Chondrus crispus) is a very common, and commercially important seaweed in Atlantic Canada. A 'red algae' growing in lower rocky intertidal zones with wave action and subtidal zones with less water movement, Irish moss displays a wide range of colors, depending on nutrient availability and light stimulation. The best fertilized Irish moss is a deep purplish-brown with tiny bright blue glints, and pigmentation declines with nutrient availability. Simply noting that Irish moss is green or yellow does not indicate an unusual condition, since this plant has always managed to grow  in habitat with lower nutrient availability where these lighter colors will normally occur. But when habitat that once supported thick, deep-purple moss now produces only short yellow plants, a decline in nutrient availability is suggested. That is what I have found; where I raked thick dark moss in summer 30 years ago, there now grows only very short, pale greenish-gold plants. And along the Atlantic coast of Nova Scotia in general, areas where moss-raking is feasible have been shrinking. (More discussion and pictures of Irish moss are in the recently added page on the shifting baseline of color in Irish moss, and the original seaweed article.)

(links to other seaweed galleries: green seaweeds - kelp - fuzzy seaweed - rockweed - barnacles )
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Short, golden moss at East Dover, where this author raked thick, purplish-brown plants circa 1970.

Summer 2002, moss bed turned white (most likely dead) at East Dover.

Another bed with many white moss plants. This appearance of Irish moss is eyecatching, and unfamiliar to longtime coastal residents.

Even at highly wave-exposed Peggy's Cove, the upper plants in the Irish moss belt are taking on bright colors. This is a far cry from a tidepool...

Late summer, 2002, inside Shad Bay, N.S. Very pale Irish moss (indicating low nutrient availability) with heavy growth of fine 'fuzzy' algae...

Similar to previous photo, the presence of the 'fuzzy' growths in this moss bed cannot be indicative of "high" nutrient availability...

White growths of coralline algae are becoming prominent in many moss beds. Corallina, more usually a pink "understory" algal growth, is bleaching too.

Subtidal moss at Shad Bay, late summer 2002. Pale yellow with very fine new growth.

The range of colors, purple through white. Also pink coralline algae which typically grows beneath Irish moss.

Constant wave movement, even on a calm day, yet Irish moss is extremely yellowed. (This is one rock that I raked dark moss from in the early 1970s.)

Highly variable in appearance, this chartreuse specimen shows bryozoan encrustation and dark spots near the tips (reproductive structures).

Several meters below low water mark, moderate wave action. Bleached moss with bleached kelp and rockweeds, and a profusion of finer, newer growths.

Bright line of color emerges from the dark seaweed on wave swept rocks at Whistler's Cove.

All photos copyright Debbie MacKenzie. Reproduce them if you like, just please credit the source.

(links to other seaweed galleries: green seaweeds - kelp - fuzzy seaweed - rockweed - barnacles )
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