Grateloupia turuturu, known as the devil's tongue weed, is a marine species of the Rhodophyta (red algae) plant, a type of seaweed, native to eastern Asia (China, Japan, Korea) and parts of eastern Russia. Due to global shipping and maritime activities, G. turuturu has become an invasive species that has altered natural communities by out-competing native seaweed species, this has resulted in a loss of habitat in many parts of the world, primarily in Australia, northern Ireland, Great Britain, and the northeastern United States. Other common names for this species are the "red menace" and "red tide".
Description
Grateloupia turuturu is a large species of seaweed that has several shades of coloring such as red, maroon, and burgundy. However, it may also be yellow when dying or deceased. It is soft and gelatinous in texture. The blades of the organism vary in size and shape; typically 1 to 8 blades will stem from a center, attached by a cylindrical holdfast. Each blade can grow to be almost a meter long, 3-15 centimeters wide, and 10-70 cm long.
Distribution
Currently, G. turuturu is found in Asia, Europe, North America, and Oceania. It is native to China, Japan, and South Korea. In Europe, it is found in France, Italy, the Netherlands, Portugal, Russia, Spain, the United Kingdom, and the Channel Islands. In North America, it is found in Mexico and in the United States, specifically in Connecticut, Massachusetts, New York, and Rhode Island. In Oceania, it is found in Australia and New Zealand.
Habitat and ecology
Grateloupia turuturu is a perennial plant living an average of 6-10 years. They grow best in nutrient-rich eutrophic waters and are commonly found on rocky layers near coastal and shallow shores. This species can quickly grow in length and peak in biomass during the late summer and early autumn months; though growth begins to wane in late spring and early summer. It has adapted to live in variable temperatures and levels of salinity(12-52 ppt), being able to continue normal growth in temperatures as low as 3°C and as high as 29°C. This is advantageous to the plant as it can withstand many environmental changes, making it an increasingly threatening and invasive species. Several small invertebrates live in proximity to G. turuturu populations, including shrimps, snails, adolescent fish and crabs. There is little evidence of herbivory on G. turuturu.
Reproduction
Grateloupia turuturu reproduce sexually, and asexually via spores and through vegetative propagation. Peak reproduction time occurs in the summer, during which time an average of 90% of individuals are fertile. Germination of this species is similar to that of many other naturally occurring seaweed, where large dense masses of non-motile aplanospores are released into the environment; since discharging spores of red algae cannot swim they must rely on water currents to transport them. When spores settle they form small rounded discs that develop via a germ tube, these discs can produce various shoots that have the ability to release thousands of additional spores. Vegetative reproduction occurs when a fragment of the plant breaks off and develops directly into new individuals, all offspring resulting from this asexual reproduction are genetically identical to each other.
Dispersal
One of the major means of transport for G. turuturu’s that enables its spread is molluscan aquaculture, or shellfish farming, this involves intentional transportation of shellfish that contains juvenile spores and/or fragments of the plant species. Transport of macroscopic spores via “stone-rafting” or drifting of fertile blades on small cobbles/rock may also occur, as well as accidental transfer on boats. Spores may also be transported in ballast water over long distances.
Uses
Grateloupia turuturu is edible.