Gelidium
Gelidium is a genus of thalloid red algae comprising 124 species. Its members are known by a number of common names.[note 1] Specimens can reach around 2–40 cm (0.79–16 in) in size. Branching is irregular, or occurs in rows on either side of the main stem. Gelidium produces tetraspores. Many of the algae in this genus are used to make agar. Chaetangium is a synonym.[1]
| Gelidium | |
|---|---|
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| Gelidium amansii | |
Scientific classification  | |
| (unranked): | Archaeplastida |
| Division: | Rhodophyta |
| Class: | Florideophyceae |
| Order: | Gelidiales |
| Family: | Gelidiaceae |
| Genus: | Gelidium J.V. Lamouroux, 1813 |
Gelidium as environmental records
Gelidium species have been collected, pressed and maintained in herbaria and personal collections from the 1850s onwards since seaweed collecting became a popular pastime for the middle classes as well as scientists in Europe and North America.[2] These numerous well-documented specimens can provide information beyond taxonomy.[3]
Sensitive measurement of stable nitrogen isotope ratios in Gelidium species collected in southern Monterey Bay between 1878 and 2018 showed a pattern of changes that matched with changes in the California current and provided support for a theory about the end of the local fishing industry.[4] Nitrogen isotope ratios are well established as a measure of nutrient productivity in aquatic ecosystems. The California current runs along coastal California and correlation with information on fish catches indicates that an increase in nutrient-rich cold water is important for fish productivity, notably sardines.[5] The California current has only been measured since 1946. The correlations with the Gelidium nitrogen ratios allowed the California current to be projected back into the nineteenth century and compared with historical records of fish catches.[4] The data matched, notably for the highest sardine catches through the 1930s and then the sudden decrease from 1945 to 1950 that ended the Monterey cannery industry. This information supports the theory that environmental changes as well as overfishing caused the collapse of the local fishery business. More broadly, this suggests that elemental analysis of historical samples of macroalgae can provide evidence of primary productivity processes. The species used included specimens of G. coulteri, G. robustum, G. purpurascens, G. pusillum and G. arborescens collected over a 140-year timespan from the 6 km coastline between Point Pinos, Pacific Grove and Cannery Row, Monterey in California, US.[4]
Species
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Notes
- Recorded common names are tengusa, makusa, genso, niu mau tsai, japansche scheleiachtige mos, steen-or klipbloem, hay tsay, olus marinus, sajur laut, tschintschau, tschoo-hoae, onikusa, hirakusa, obusa, rødalge-slaegt, gelídeos, punalevä-suku, tokoroten, kanten, tokoro-tengusa, kinukusa, isingglass, hai-ten-gusa, tocoroten, tengusa-agar, limu lo-loa, hai-tengusa, onigusa, oyakusa, kanten weed, goumaocai, hime tengusa, shihua and tanmae.
References
- Guiry, M.D.; Guiry, G.M. (2008). "Gelidium". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Retrieved 2009-04-18.
- Tronchin, E. M.; Freshwater, D. W.; Bolton, J. J.; Anderson, R. J. (2002). "A Reassessment and Reclassification of Species in the Genera Onikusa Akatsuka and Suhria J. Agardh ex Endlicher (Gelidiales, Rhodophyta) Based on Molecular and Morphological Data". Botanica Marina. 45 (6): 548–558. doi:10.1515/BOT.2002.058.
- Giaimo, Cara. "The Forgotten Victorian Craze for Collecting Seaweed". Atlas Obscura. Retrieved 27 October 2020.
- Trethewey, Laura. "What Victorian-era seaweed pressings reveal about our changing seas". The Guardian. Retrieved 27 October 2020.
- Miller, Emily A; Lisin, Susan E; Smith, Celia M; Van Houtan, Kyle S (2020). "Herbaria macroalgae as a proxy for historical upwelling trends in Central California". Proceedings of the Royal Society B. 287: 20200732. doi:10.1098/rspb.2020.0732. Retrieved 27 October 2020.
- Ware, D M; Thompson, R E (1991). "Link between longterm variability in upwelling and fish production in the northeast Pacific Ocean". Can. J. Fish. Aquat. Sci. 48: 2296–2306. doi:10.1139/f91-270. Retrieved 27 October 2020.
- Toefy, R., Gibbons, M.J. & McMillan, I.K. 2005. The foraminifera associated with the alga Gelidium pristoides, South Africa. African Invertebrates 46: 1-26.