Chondracanthus exasperatus, commonly called Turkish towel, is a species of seaweed in the family Gigartinaceae. The specific epithet exasperatus (lit. 'roughened') is due to the bumpy texture of the blades (leaf-like structures). This texture also leads to the common name which evokes the luxurious feel of a towel from a Turkish bath. The rough, papillae-strewn blade surface even makes it difficult to measure the temperature using infrared thermometers.
It is a perennial species. Like many species in Gigartinaceae, the appearance of C. exasperatus can vary depending upon grown conditions. It can be confused with Chondracanthus spinosus and Gigartina binghamiae, and it might take RFLP analysis to be sure of the species. In addition, the names of the species in the genera Gigartina and Chondracanthus have been adjusted several times since 1961. The leaf margins of the blades are smooth in cooler water and then become toothed and jagged as the temperature increases. Increased water velocity will cause the blades to change shape. The color of the thallus is greenish when exposed to ultraviolet light, but when it grows in deeper water it is darker red to purple. Though it prefers lower water temperatures it can grow at 25 °C, but ends up dark red to black in color and having flat or cylindrical branch clusters.
As originally described, C. exasperatus has a leafy stipe, with large 2–3 feet (0.61–0.91 m) long leathery-membranaceous blades that are lanceolate and simple. The blade, and the majority of the thallus, is purplish-red. Blade margins are thick, with rounded teeth, and appendiculate. The thallus has simple, ramenta-like spiny projections (papillae) thickly strewn on both sides. Coccoid pedicels are in marginal spines emerging from the thallus.
Distribution and habitat
C. exasperatus is found on the Pacific coast of North America from Baja California north to Sitka Sound. The type locality is in Puget Sound opposite Fort Nisqually. It grows on rocks in semi-exposed or semi-protected areas of the upper subtidal to lower intertidal zone, down to a depth of 20m.
Proliferation of invasive species such as Mazzaella japonica have a negative impact on the growth of C. exasperatus. C. exasperatus is also susceptible to infection by the parasitic oomycete Pythium marinum.
C. exasperatus decomposes quickly, faster than most other species, indicating its importance to detritivores and to nutrient cycling. The high rate of decomposition also means that it is harder to find washed ashore as wrack and that its importance in the ecosystem may be underrepresented in research.
However, amphipods such as Megalorchestia californiana and Traskorchestia spp. (including Traskorchestia traskiana) will avoid C. exasperatus. The isopod Ligia pallasii and the green sea urchin (Strongylocentrotus droebachiensis) also seems to prefer to eat other seaweed species. A diet of C. exasperatus can slow or decrease shell length in juvenile white abalone (Haliotis sorenseni) at extreme water temperatures, and possibly can be deadly at 18 °C or above raising concerns related to global warming.
Use by humans
Commercial aquaculture in both tanks and on nets of C. exasperatus was attempted as early as the 1970s in Washington state. It can also be grown in the air if sprayed with sea water, which conserves water but risks losing the crop if the pumps fail. The gel within the blades has also been harvested to make cosmetics. Intact blades are used in baths or for thalassotherapy, along with species such as feather boa (Egregia menziesii), finger kelp (Laminaria digitata), and Fucus.
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This taxon has not yet been assessed for the IUCN Red List, and also is not in the Catalogue of Life.
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Authority: (Harvey et Bailey) Hughey North Pacific Distribution: Sitka Sound, Alaska, to Baja California, Mexico. Phylum: Rhodophyta Class: Florideophyceae Order: Gigartinales Family: Gigartinaceae Former Scientific Names: Gigartina exasperata Description: Thallus is a thick (somewhat rubbery), elongate, undivided purplish to pale red blade, reaching 30 cm (12 in) tall, with short, spiny papillae covering the blade surface. Blades arise as elongate papillae-like projections from a discoidal holdfast up to 1 cm (0.4 in) in diam. Habitat: This perennial grows on rock in the low intertidal and upper subtidal of semi-protected to semi-exposed habitats.
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5. Gigartina (Mastocarpus) exasperata H. et B., frondis stipite mox in laminam coriaceo-membranaceam bi-tripedalem late lanceolatam integram dilatata, margine incrassato eroso-dentato et appendiculato, disco utrinque spinulis simplicibus ramosisve dense consperso, coccidiis pedicellatis in spinulis marginalibus et e disco ortis immersis. Hab. Opposite Fort Nisqually, Puget Sound.
- Gadberry, Bradley A.; Colt, John; Boratyn, Diane C.; Maynard, Desmond J.; Johnson, Ronald B. "INTENSIVE LAND-BASED FARMING OF RED AND GREEN MACROALGAE IN THE PACIFIC NORTHWEST: AN EVALUATION OF SEASONAL GROWTH AND PROXIMATE COMPOSITION". Aquaculture America 2015 - Meeting Abstract. World Aquaculture Society. Retrieved 29 January 2018.
The specific growth of all three species exhibited a similar pattern with the highest specific growth rate observed during summer months (C. exasperatus 7.8%, U. rigida 6.2% and P. palmata 8.2%). Growth of all three species was lowest around the winter solstice
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Zoospores encysted on thalli of species of red algae other than Porphyra. Using the disc assay, encystment by Py. marinum was observed on Gigartina exasperata Harvey et Bailey (tetrasporophyte)...
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- US patent US6136329 A, Diane C. Boratyn, "Compositions and methods relating to intra-lamellar gels from algae", published 24 October 2000, assigned to Diane C. Boratyn
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- Media related to C. exasperatus at Wikimedia Commons
- Data related to C. exasperatus at Wikispecies
- C. exasperatus page at ARCTOS
- C. exasperatus page at Ocean Biogeographic Information System
- C. exasperatus page at iSpecies
- C. exasperatus page at Open Tree of Life
- C. exasperatus page at CrossRef
- Chondracanthus page at Interim Register of Marine and Nonmarine Genera
- C. exasperatus page at Biodiversity of the Central Coast
- C. exasperatus page at The Barcode of Life Data System
- C. exasperatus page at uBio