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| Dictyosphaeria | |
|---|---|
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Scientific classification  | |
| (unranked): | Viridiplantae |
| Division: | Chlorophyta |
| Class: | Ulvophyceae |
| Order: | Cladophorales |
| Family: | Siphonocladaceae |
| Genus: | Dictyosphaeria Decaisne |
Dictyosphaeria is a genus of green algae (class Ulvophyceae) in the family Siphonocladaceae. [1]
The genus Dictyosphaeria belongs to the order of Cladophorales and family Siphonocladaceae. It comprises a total of 13 taxonomically recognized species. [2]
Below is a list of taxonomically accepted species from the genus Dictyosphearia:
The thalli are composed of visibly hollow hexagonal or polygonal cells; and are monostromatic or polystromatic depending on species. They can be solid or button-shaped at around 1–5 cm; and spherical and club-shaped at 1 cm or more. The size of each cells are around 300 - 500 μm in diameter. Complex rhizoidal system is absent, however, basal cells are firmly attached to the substratum. [3]
The coloration of the macroalgae varies from grass green to bluish. [4]
Cells are visible to the naked eye. They are minutely determinate, simple or furcate, and tenacular[ check spelling ] that are structurally cushioned together. Occasionally, tenacular cells may also function as adventitious rhizoids.
Cells are multinucleated and have numerous discoid chloroplasts. Chloroplasts bear single pyrenoid surrounded by starch sheath and divided to two or more portions by traversing thylakoids.
The life cycle of Dictyosphaeria exhibits both biphasic and isomorphic alternation of generation. This involves quadriflagellate zoospores, as well as isogamous and biflagellate gametes. Asexual reproduction through thalli fragmentation and possible parthenogenesis of gametes which result in smooth surface thalli textures.
In addition, since this macroalgae is a large cell unit, mitotic division and cytokinesis were observed in the development of the zoospores. The unique process of cell division in this genus is observed in a study by Hori and Enomoto (1978). The mitotic spindle is placed centrally at the early course of the zooid differentiation. Prophase nuclei with centrioles were observed to be present during this stage only. Other mitotic stages are observed together in the network cytoplasm [5]
The genus Dictyosphaeria is widely found in the tropical region. Its habitat varies from shallow intertidal to subtidal areas, growing on coral or rocky rubbles in reef flats where they can be the dominant macroalgae. They are commonly found attached to rocky substrate either air-exposed, or submerged in water exposed in waves. [6]
The genus Dictyosphaeria, particularly the species D. cavernosa is used for fish bait and animal feed. [7]
Natural products such as the novel metabolite dictyosphaerin, a bicyclic lipid compound were extracted from Dictyosphaeria, particularly Dictyosphaeria sericea. This compound is being studied for its potential application in both scientific and medical applications. [8] In addition, Dictyosphearia also harbors microorganisms such as the fungal species that belong to the genus Penicillium. A study by Bugni et al. (2008), has shown that isolated fungal specimens from the species Dictyosphaeria versluysii were found to produce novel metabolites including the polyketides dictyosphaeric acids A and B, and the anthraquinone carviolin. [9]
In the Kāne'ohe Bay in Hawai'i, USA, Dictyosphaeria cavernosa are considered as invasive species resulting from continuous discharge of nutrient wastes from coastal communities, as well as reduction in herbivore pressures (such as from fish) in the area. [10] As early as the year 1970, reduced coral cover and increased spatial expansion of Dictyosphaeria cavernosa were already documented in the Kaneohe bay area. [11] Invasion of the macroalgae could be attributed to the simultaneous population growth and watershed development as early as the 1960s, including the phase shift on the bay's reef systems.
In a following study, after a steady increase in abundance of Dictyosphaeria cavernosa for more than 40 years in the Kāne'ohe Bay, the population suddenly experience a tremendous decrease in cover (Year 2006). This depletion in algal cover appears to be the result of an unusually prolonged cloudy and rainy period. Reduction in irradiance may have caused a decrease in biomass of D. cavernosa in the area. However, coral cover remains to be low due to the physical structure of the reef (unstable rocky substrate) which can be difficult for coral larvae recruits to settle. [12]
Bacterioplankton community structure were also found to be influence by Dictyosphaeria genus, specifically, Dictyosphaeriaocellata. When exposed to the macroalgae, the bacterial community structures changes: seven (7) bacterial phylotypes were eliminated, while five (5) phylotypes persisted. Moreover, in the laboratory setting, extracts from D. ocellata where observed to influence the difference in growth rates of bacteria in culture. [13]
Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of red, but some species can be purple, yellow, blue, white, or gray-green. Coralline algae play an important role in the ecology of coral reefs. Sea urchins, parrot fish, and limpets and chitons feed on coralline algae. In the temperate Mediterranean Sea, coralline algae are the main builders of a typical algal reef, the Coralligène ("coralligenous"). Many are typically encrusting and rock-like, found in marine waters all over the world. Only one species lives in freshwater. Unattached specimens may form relatively smooth compact balls to warty or fruticose thalli.
Halimeda is a genus of green macroalgae. The algal body (thallus) is composed of calcified green segments. Calcium carbonate is deposited in its tissues, making it inedible to most herbivores. However one species, Halimeda tuna, was described as pleasant to eat with oil, vinegar, and salt.
Polysiphonia is a genus of filamentous red algae with about 19 species on the coasts of the British Isles and about 200 species worldwide, including Crete in Greece, Antarctica and Greenland. Its members are known by a number of common names. It is in the order Ceramiales and family Rhodomelaceae.
The ring-tailed cardinalfish is a widespread fish species in the family Apogonidae found in the Red Sea and off East Africa to Papua New Guinea, north to Japan, and south to Australia.
Bryopsis is a genus of marine green algae in the family Bryopsidaceae. It is frequently a pest in aquariums, where it is commonly referred to as hair algae.
Udotea is a genus of green algae in the family Udoteaceae.
Valonia is a genus of green algae in the Valoniaceae family. The genus Ventricaria is now regarded as a synonym of Valonia.
Turbinaria is a genus of brown algae (Phaeophyceae) found primarily in tropical marine waters. It generally grows on rocky substrates. In tropical Turbinaria species that are often preferentially consumed by herbivorous fishes and echinoids, there is a relatively low level of phenolics and tannins.
Arnarvon Islands are a group of islands in Solomon Islands. They are located in Isabel Province and nearby to Wagina Island in Choiseul Province.
The Phoenix Islands Protected Area (PIPA) is located in the Republic of Kiribati, an ocean nation in the central Pacific approximately midway between Australia and Hawaii. PIPA constitutes 11.34% of Kiribati's exclusive economic zone (EEZ), and with a size of 408,250 km2 (157,630 sq mi), it is one of the largest marine protected areas (MPA) and one of the largest protected areas of any type on Earth. The PIPA was also designated as the world's largest and deepest UNESCO World Heritage Site in 2010.
Hydroclathrus is a genus of perforate brown alga, of the phylum Ochrophyta and the class Phaeophyceae.
Asparagopsis is a genus of edible red macroalgae (Rhodophyta). The species Asparagopsis taxiformis is found throughout the tropical and subtropical regions, while Asparagopsis armata is found in warm temperate regions. Both species are highly invasive, and have colonised the Mediterranean Sea. A third accepted species is A. svedelii, while others are of uncertain status.
Coral bleaching in Oahu has been on the rise since 1996, when Hawaii's first major coral bleaching occurred in Kaneohe Bay, followed by major bleaching events in the Northwest islands in 2002 and 2004. In 2014, biologists from the University of Queensland observed the first mass bleaching event, and attributed it to The Blob.
The Coral reefs of the Solomon Islands consists of six major islands and over 986 smaller islands, in Oceania, to the east of Papua New Guinea and northwest of Vanuatu. The Solomon Islands lie between latitudes 5° and 13°S, and longitudes 155° and 169°E. The distance between the westernmost and easternmost islands is about 1,500 km (930 mi). The Santa Cruz Islands are situated north of Vanuatu and are especially isolated at more than 200 km (120 mi) from the other islands. The Solomon Islands has the 22nd largest Exclusive Economic Zone of 1,589,477 km2 (613,701 sq mi) of the Pacific Ocean.
Crustaphytum is a genus of red alga first discovered in Taoyuan algal reefs by Taiwanese scientists. The epithet “crusta” refers to crustose thallus and “phytum” refers to plant. Belonging to the family Hapalidiaceae in the order Hapalidiales, Crustaphytum is one kind of crustose coralline algae.
Mesospora negrosensis is a species of macroalga occurring in the western Atlantic.
Mesospora is a genus of macroalgae that was described by Anna Weber-van Bosse in 1911. Although considered a taxonomic synonym of Hapalospongidion, the World Register of Marine Species cites six accepted species of the genus.
Dictyosphaeria cavernosa is a species of green algae in the family Siphonocladaceae, one of the three species in this family. Its common name is green bubble seaweed.
Dictyosphaeria versluysii is a species of green algae in the family Siphonocladaceae. This species is indigenous to Indonesia, with a world distribution ranging from the Pacific regions and extending to the Indian Ocean. It can be found in various countries including Mexico, China, Thailand, Vietnam, the Philippines, Australia, and Hawaii.
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