Lobophora (alga) explained

Lobophora is a genus of thalloid brown seaweed of the Phylum Ochrophyta; Class Phaeophyceae.

Taxonomy and nomenclature[1]

The genus Lobophora belongs to the Order Dictyotales; Family Dictyotaceae, and additionally to the Tribe of Zonarieae.

Currently, there are a total of seventy-one (71) taxonomically accepted species belonging to this genus:

General morphological characteristics[2] [3]

Thalli

Thalli are foliose or fan-shaped and possess different growth morphologies: decumbent, procumbent, crustose, conk-like (shelf-like), fasciculate, and stipitate, depending on species and habitat.[4] Thalli arises from matted rhizoidal holdfast with branched fronds displaying broadly flabellate to irregularly branched forms. Algal hairs are arranged in concentric lines or scattered turf. Size can reach up to 20 cm long. Coloration are commonly light brown to dark-brown.

Cellular structure (internal morphology)

Thalli is 7-12 cells thick, with the outermost layers composed of cortical cells overlying innermost layer of larger medullary cells. Medullary cells usually exhibit uniform sized except for the larger central cells. Discoid chloroplasts are found at the cortical layers.

Reproductive structures

The sporangial sori of Lobophora are either scattered or in concentric bands found at the surface of the thallus They are characteristically indusiated but without paraphyses. Sporangia without a basal stalk cell produce up to eight (8) spores. Oogonia are found in sori on both side of the frond surfaces.

Life history

The life history of Lobophora is currently unknown. But it may have similar stages with other members from Dictyotaceae Family.

Distribution and habitat

The genus Lobophora are found throughout the pantropical and even temperate regions. They are found growing on solid substrate (rocks) at intertidal (some are wave-exposed) to subtidal areas of rocky-reef habitats.[5]

Ecology and impacts

Seaweeds, such as Lobophora are naturally occurring in coral reefs. Under normal conditions, the interactions between Genus Lobophora and corals pose no threat and can co-exist in an ecosystem. This is attributed to the control of algal populations by coral chemical defense and herbivory. However, when these contributing control factors become unbalanced, Lobophora and other associated seaweeds become opportunistic in taking over reefs (i.e. increasing spatial cover) and by density-dependent negative feedback, prevents corals from settling on substrate. However, as mentioned earlier, Lobophora a species-rich group and certain individuals have different growth patterns, interactions, and habitat-preferences. Understanding and determining its taxa is utmost important.[6]

Because of capacity of seaweeds, such as Lobophora to occupy large spatial habitats, particularly in degraded reefs, they can have an impact on the chances of coral larvae to settle on a substrate. Lobophora can inhibit coral settlement, however, its effect can decrease later on life history stages because they have no effect on growing coral nubbins. Chances of coral larvae to settle in degraded reef followed by disturbance may be challenging.[7]

As mentioned, Lobophora are highly preferred by herbivores particularly fish. Growth morphological defenses have been developed by this group to become unpalatable to its herbivores. Encrust (crustose) forming Lobophora, such as L. variegata are dominant in areas with high concentration of herbivorous fish and sea urchin, compare to other seaweeds having a foliose or decumbent morphologies. This indicates that high herbivory activities in the area may influence the defense mechanisms of seaweeds, in the case of Lobophora, its specific growth morphologies.[8] [9] Varying metabolomic concentration differs from Lobophora species when exposed to changing natural habitats and substrates. Fatty acids derivatives and polyolefins were identified as chemomarkers of these changing conditions. This indicates possible chemical plasticity of metabolites in the genus. Different Lobophora may composed varying natural products depending on bioregion.[10]

Economic importance/ natural products

Similar to other seaweeds, Genus Lobophora has a variety of natural products. There are: Minerals: cadmium (Cd), copper (Cu), mercury (Hg), iodine (I), nickel (Ni), lead (Pb), and zinc (Zn); Pigments: carotene, chlorophyll a, chlorophyll c, fucoxanthin; Polysaccharides/ simple sugars: alginic acid, laminarin; Sugar alcohol: mannitol.[11]

In addition Lobophora may have contributions in medicinal application. Sulfated polysaccharides, fucans, from algae Lobophora variegata were shown to have anti-inflammatory activity in acute zymosan-induced arthritis in laboratory rats. It resulted in treatments by reducing cell infiltration in the synovial membrane with a decrease in TNF-α. It was also shown that heterofucans are strong antioxidants.[12] Another is Lobophora has antiprotozoal activity against parasitic protozoans such as Giardia intestinalis, Entamoeba histolytica and Trichomonas vaginalis. Extract from L. variegata shows promising result in the treatments of protozoan infection. The chloroform fraction of the extract contained a major sulfoquinovosyldiacylglycerol (SQDG), identified as 1-O-palmitoyl-2-O-myristoyl-3-O-(6´´´-sulfo-a-D-quinovopyranosyl)-glycerol, together with small amounts of 1,2-di-O-palmitoyl-3-O-(6´´´-sulfo-a-D-quinovopyranosyl)-glycerol, and a new compound identified as 1-O-palmitoyl-2-O-oleoyl-3-O-(6´´´-sulfo-a-D-quinovopyranosyl)-glycerol were identified having strong antiprotozoal attributes.[13]

Notes and References

  1. Web site: Algaebase Taxonomy Browser - Genus: Lobophora.
  2. Web site: Algaebase: Lobophora J.Agardh, 1894.
  3. Book: Trono Jr., Gavino C.. Field Guide & Atlas of Seaweed Resources of the Philippines. Bookmark. 1997. 971-569-252-4. Makati City, Philippines. 111. English.
  4. 2014. Toward an inordinate fondness for stars, beetles and Lobophora? Species diversity of the genus Lobophora (Dictyotales, Phaeophyceae) in New Caledonia. Journal of Phycology. 10.1111/jpy.12243. 50. 6. 1101–1119. Vieira. Christophe. d'Hondt. Sofie. De Clerck. Olivier. Payri. Claude E.. 26988791. 10155133.
  5. 2021. New records of the genus Lobophora (Dictyotales: Phaeophyceae) for the marine flora of Cuba and their distribution in the Greater Caribbean Sea. Revista Mexicana de Biodiversidad. 92. 923538. 10.22201/ib.20078706e.2021.92.3538. 236260162. Torres-Conde. Eduardo Gabriel. Zúñiga-Delgado. Jorge Gabriel. Reyes-Pérez. Denise Lázara. Suárez. Ana M.. free.
  6. 2020. Lobophora–coral interactions and phase shifts: summary of current knowledge and future directions. Aquatic Ecology. 54. 1–20. 10.1007/s10452-019-09723-2. 202641944. Vieira. Christophe.
  7. 2019. Stage-specific effects of Lobophora on the recruitment success of a reef-building coral. Coral Reefs. 38. 3. 489. 10.1007/s00338-019-01804-w. 2019CorRe..38..489E. 116864118. Evensen. Nicolas R.. Doropoulos. Christopher. Wong. Kelly J.. Mumby. Peter J..
  8. 1989. Morphological variation and differential susceptibility to herbivory in the tropical brown alga Lobophora variegata. Marine Ecology Progress Series. 54. 3. 287–298. 10.3354/meps054287. 24833763. 1989MEPS...54..287C. Coen. LD. Tanner. CE. free.
  9. Lobophora (Dictyotales) Species Richness, Ecology and Biogeography Across the North-Eastern Atlantic Archipelagos and Description of Two New Species1. Journal of Phycology. 2020. 56. 2. 346–357. 10.1111/jpy.12956. 31849038. 209409237. Vieira. Christophe. Henriques. Filipe. d'Hondt. Sofie. Neto. Ana. Almada. Carmen H.. Kaufmann. Manfred. Sansón. Marta. Sangil. Carlos. Clerck. Olivier De. 10400.13/3687. free.
  10. 2019. High metabolic variation for seaweeds in response to environmental changes: a case study of the brown algae Lobophora in coral reefs. Scientific Reports. 9. 1. 993. 10.1038/s41598-018-38177-z. 30700781. 6353962. 2019NatSR...9..993G. Gaubert. Julie. Payri. Claude E.. Vieira. Christophe. Solanki. Hiren. Thomas. Olivier P..
  11. Book: Trono, Gavino C. Jr.. Field Guide & Atlas of Seaweed Resources of the Philippines. Bookmark. 1997. 971-569-252-4. Makati City, Philippines. 112. English.
  12. 2011. Antioxidant and anti-inflammatory effect of polysaccharides from Lobophora variegata on zymosan-induced arthritis in rats. International Immunopharmacology. 11. 9. 1241–1250. 10.1016/j.intimp.2011.04.003. 21504801. Paiva. Almino Afonso de O.. Castro. Allisson J.G.. Nascimento. Marília S.. Will. Luiza Sheyla E.P.. Santos. Nednaldo D.. Araújo. Renata M.. Xavier. Caroline A.C.. Rocha. Francisco Airton. Leite. Edda Lisboa. free.
  13. 2010. The Tropical Brown Alga Lobophora variegata: A Source of Antiprotozoal Compounds. Marine Drugs. 8. 4. 1292–1304. 10.3390/md8041292. 20479979. 2866487. free. Cantillo-Ciau. Zulema. Moo-Puc. Rosa. Quijano. Leovigildo. Freile-Pelegrín. Yolanda.

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