Laurencia
Laurencia is a genus of red algae that grow in temperate and tropical shore areas, in littoral to sublittoral habitats, at depths up to . Description. "Laurencia" species have a thallus that is erect or decumbent with distichous, whorled or radial branch arrangement. Taxonomy and Nomenclature. "Laurencia" was first classified by Lamouroux in 1813, which included an initial description of eight species which then subsequently underwent taxonomic revisions. The genus belongs to order Ceramiales reported to have 137 species, with a rich body of knowledge spanning for more than 50 years of research. "Laurencia" belongs to the family Rhodomelaceae which  is considered to be one of the largest marine red algae family, estimated to have 125 genera and 700 species all over the world. In Laurenciae, a tribe consisting of eight genera, have a taxonomic group called ""Laurencia complex"" or "Laurencia" sensu lato which includes six of eight genera, "Chondrophycus, Laurencia, Laurenciella, Osmundea, Palisada," and "Yuzurua". Morphology. "Laurencia" is a small to medium sized red algae which may appear to be iridescent with thalli reaching up to 40 cm. Thalli can be branching, which can either be bilateral or spread in all directions. Its appendages can be rhizoidal or discoidal  in appearance on stoloniferous holdfasts. Branch shape appears to be flat or cylindrical in morphology. Branchlets may be slightly rigid with a shape that may be blunt, truncate or claviform. "Laurencia" has shown high diversity as a genus, with species having distinct features that can easily be determined within the "Laurencia" complex. Molecular studies using rbcL (RuBisCO, Ribulose-1,5-Bisphosphate Carboxylase Oxygenase, Large chain) have uncovered evidences which divided the "Laurencia" complex, identiying the genus "Laurenciella," which shares similar morphology with "Laurencia" but has a different rbcL sequence. Distribution. "Laurencia" can be found all over the world, in particular in tropical  and subtropical regions with warmer waters. Its habitats range from tide pools, reef flats, mud flats, and a variety of hard substrates (e.g. rocks, corals), within intertidal and subtidal zones up to 65 m. It is also described as "turf-forming" wherein it can cover a majority of hard substrate in some areas. In Myanmar, it can be found growing together with some species of "Cladophora, Chaetomorpha, Dictyota, Gelidium, Ceramium, Caloglossa, Catenella, Polysiphonia, Acanthophora," and "Bostrychia". Ecology. "Laurencia" has numerous ecological roles, serving as refuge for different marine organisms in areas where they grow abundantly, forming forests. They are also  hosts of various mircoorganisms and parasitic algae, known as "Janczewskia""." As producers, they are also fed on by some grazers such as crabs, queen conch, and sea hares despite its chemical deterrent. The growth of "Laurencia" is significantly affected by changes in nutrient availability and temperature. The effects of pollution in "Laurencia" are somewhat inconsistent showing its adaptability in Indian Ocean but markedly showed a decrease in biomass in polluted areas in the Mediterranean. Space within the environment is also a necessity for "Laurencia" survival. In field trials, "Laurencia" tends to inhibit coral larvae dispersal resulting to higher mortality when  the algae is present. Life History. "Laurencia" grows throughout the year, with spermatangial individuals appearing from early August to late September while cystocarpic ones appear from mid-August to late October. From July to October, mature tetrasporangial plants appear. Gametophytic individuals are dioecious in nature, typically developed on the branchlets, but can be present in the main branch as well. Male gametophytes contain spermatangia on trichoblast while female gametophytes contain carpogonia, representing the haploid phase. Two diploid phases occur in "Laurencia": one with carpogonia and carpospore and the other, with tetrasporangia. Therefore, "Laurencia" undergoes three phases in its life cycle : one haploid phase and two diploid phases, consistent to the "Polysiphonia" triphasic life history. Cultivation and Exploitation. A growing interest in the cultivation of "Laurencia brongniartii" has emerged due to its potential to be a newfound source for antibiotics. The common method is indoor tank culture, utilizing an excised apical tip from a thalli sample. Initial trials have confirmed its viability for culture providing opportunities for personnel with little to no experience in algae cultivation. The cost of production is relatively low, with maintenance costs at its core. Small-scale operations may be profitable in maximizing algae production, however more  studies are needed to evaluate these conditions. Chemical Composition. "Laurencia" species are known to have several natural products exhibiting numerous biological activities such as chemical defense against grazers, anti-fouling chemical affecting "Perna perna" attachment, and anti-fouling activities. In addition, "Laurencia" is known to be an abundant source of halogenated metabolites, including a variety of terpenes (e.g. sesquiterpenes, diterpenes, triterpenes, and C acetogenins). In Vietnam, "L. snackeyi" may be a potential species to evaluate new chemical races, similar to "L. nipponica" seeing how these may indicate similarities in morphology but differences in chemical content subject to geographical distribution. Utilization  and Management. A total of 1047 secondary metabolites have been extracted from "Laurencia" and "Aplysia" species since 2015. The diverse chemical composition of "Laurencia" has been subject to numerous research mainly attributed to both environmental and genetic factors. For years, humans have utilized "Laurencia" as food, medicinal products, fertilizers, and from recent research, an abundant source of pharmacological significance. The commercialization of the species may require further research in order to optimize culture conditions and eventually, harvest greater yield and develop a more systematic cultivation system. Species. AlgaeBase, a database with detailed information on species of "Laurencia", includes 137 taxonomically  accepted species , and differentiates these from a further ~375 entries of uncertain taxonomic status; it further delineates homotypic or heterotypic synonyms. Commonly observed species of "Laurencia" include the shallow subtidal "Laurencia nidifica" (Hawaii), "Laurencia pacifica" (California), and "Laurencia thyrsifera" (New Zealand). Species seen in the British Isles include "Laurencia hybrida", "Laurencia obtusa", "Laurencia osmunda", "Laurencia pinnatifida", "Laurencia pyramidalis", and "Laurencia truncata". The World Register of Marine Species lists the following species as accepted: Uses. "Laurencia nidifica" is used as a condiment in Hawaii due to its peppery taste.