Ecology
provided by NMNH Marine Dinoflagellates
A. monilatum is a planktonic estuarine dinoflagellate species associated with toxic red tides and massive fish mortality events in warm coastal waters off Florida, Texas and Venezuela (Howell 1953; Ray & Aldrich 1967). Offshore coastal water blooms have also been reported in Florida and Texas (Williams & Ingle 1972; Wardle et al. 1975). One reported red tide from Texas had cell concentrations ranging from 5 X 105 cells/L to 10 X 105 cells/L (Gates & Wilson 1960).
This species produces a dark colored resting cyst as part of its life cycle. The cyst is smooth and round to ovoid. Cysts range in size from 60 to 87 µm in diameter (Fig. 6) (Walker & Steidinger 1979).
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Habitat and Locality
provided by NMNH Marine Dinoflagellates
Alexandrium monilatum is a warm water species known from subtropical and tropical regions of the Atlantic Ocean: east coast of Florida (Howell 1953), Venezuela in the Caribbean Sea (Halim 1967), and Texas in the Gulf of Mexico (Gunter 1942; Connell & Cross 1950; Ray & Aldrich 1967). Populations have also been reported from the tropical Pacific Ocean off Ecuador (Balech 1995), and surprisingly in the Chesapeake Bay (Morse 1947).
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Morphology and Structure
provided by NMNH Marine Dinoflagellates
A. monilatum is a photosynthetic species with central radiating brownish chloroplasts. The quarter-moon shaped nucleus is equatorial (Balech 1995).
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Nomenclatural Types
provided by NMNH Marine Dinoflagellates
Holotype: Gonyaulax monilata Howell, 1953: 153, figs. 1-5
Type Locality: North Atlantic Ocean: Indian River, Florida, USA
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Reproduction
provided by NMNH Marine Dinoflagellates
A. monilatum reproduces asexually by binary fission; plane of fission is oblique. This species also has a sexual cycle with armoured isogamous gametes that fuse with cingula at oblique angles (Fig. 5). Gametes range in size from 36 X 36 µm to 47 X 56 µm. After fusion, a planozygote forms which then encysts into a characteristic resting cyst (Fig. 6) (Walker & Steidinger 1979).
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Species Overview
provided by NMNH Marine Dinoflagellates
A. monilatum is an armoured, marine, planktonic dinoflagellate. It is a coastal warm water species associated with toxic red tides and massive fish and shellfish kills.
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Synonyms
provided by NMNH Marine Dinoflagellates
Gonyaulax monilata Howell, 1953
Gessnerium mochimaensis Halim, 1967
G. monilata (Howell) Loeblich, 1970
Pyrodinium monilatum (Howell) Taylor, 1976
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Taxonomic Description
provided by NMNH Marine Dinoflagellates
A very distinctive chain-forming species, A. monilatum typically occurs in long chains of 16 or more cells. Single cells are medium to large, wider than long, and flattened anterio-posteriorly (Figs. 1, 2). Epithecal shoulders are occasionally observed. Thecal plates are thin with many delicate pores. Cells range in size between 28-52 µm in length and 33-60 µm in transdiameter width (Balech 1995; Taylor et al. 1995; Steidinger & Tangen 1996).
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Thecal Plate Description
provided by NMNH Marine Dinoflagellates
The plate formula for A. monilatum is: Po, 4', 6'', 6c, 10s, 5''', 2''''. The large apical pore complex (APC) is broadly triangular and slightly curving posteriorly. The large apical pore plate (Po) is ovate with a small comma-shaped foramen (Fig. 3). The anterior attachment pore (aap) is large and round (Fig. 3). Small pores are present along the margin of the Po. The characteristic first apical plate (1') is not connected to the Po; it is short and broadly pentagonal (Figs. 2, 3). The 1' plate is typically without a ventral-pore, however, specimens from Florida reveal a pore at the juncture where the 1', 2' and 4' plates meet (Fig. 2) (Balech 1995; Taylor et al. 1995; Steidinger & Tangen 1996).
The epitheca and hypotheca are nearly equal. The antapex is slightly concave. The median cingulum is deeply excavated, devoid of lists, and is displaced in a descending fashion one time its width (Fig. 2). The sulcus bears a diagnostic feature: a large and rhomboid-shaped posterior sulcal plate (s.p.) (Fig. 4). The s.p. is concave and recessed with radial markings, and contains a large central posterior attachment pore (pap (Fig. 4) (Balech 1995; Taylor et al. 1995; Steidinger & Tangen 1996).
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Toxicity
provided by NMNH Marine Dinoflagellates
Alexandrium monilatum produces a strong ichthyotoxin resulting in a paralyzing effect (Gates & Wilson 1960, Ray & Aldrich 1967). From laboratory culture studies, Schmidt and Loeblich (1979) report production of paralytic shellfish poison (PSP) toxins: saxitoxin (STX) and gonyautoxins (GTX); the toxins are hemolytic and neurotoxic (Bass & Kuvshinoff 1982; Clemons et al. 1980). The toxins produced from this species do not accumulate in shellfish (molluscs do not feed on this species) and it is not toxic to birds (Ray & Aldrich 1967). Massive fish kills have been reported from Texas bays in the Gulf of Mexico (Gunter 1942; Connell & Cross 1950; Ray & Aldrich 1967) and on the east coast of Florida in the Atlantic Ocean (Howell 1953).
- bibliographic citation
- Faust, Maria A. and Rose A. Gulledge. Identifying Harmful Marine Dinoflagellates. Smithsonian Contributions from the United States National Herbarium, volume 42: 1-144 (including 48 plates, 1 figure and 1 table).
Alexandrium monilatum
provided by wikipedia EN
Alexandrium monilatum is a species of armored, photosynthetic, marine dinoflagellates. It produces toxins that, when present in high concentrations as "red tides", can kill fish and reduce growth rates of shellfish.
Distribution and habitat
Alexandrium monilatum is a planktonic species found in tropical to warm temperate coastal seas and estuaries of the Americas. The species description is based on material from the Indian River Lagoon on the Atlantic Coast of Florida.[1]
Description
Alexandrium monilatum are armored or thecate dinoflagellates with an outer cell wall covered with cellulose plates. A. monilatum is wider at the cingulum or equatorial girdle than it is tall, and it commonly joins into chains of from two to sixteen individuals, with chains as long as 32 cells in calm seas. The cingulum or groove halfway between the top and bottom of the organism's single cell is where the pair of flagella are situated. To form chains, A. monilatum cells exude a glue from the apical or top attachment pore of one individual to make it adhere to the antapical or bottom attachment pore of the next individual in the chain. Organisms produced in laboratory cultures do not usually form chains. The nucleus is located in the center of the cell, and A. minilatum's many chloroplasts radiate outward from the nucleus.[1][2] A bioluminescent strain of A. monilatum has been identified from Mississippi Sound in the Gulf of Mexico.[3]
Life cycle
Alexandrium monilatum reproduces both asexually and sexually. Asexual reproduction is by binary fission. Though less common than fission, A. monilatum also reproduces sexually. This takes place when a zygote is formed by the fusing of the two isogametes and resting cysts may be formed.[2]
Toxicity
Like other dinoflagellates, Alexandrium monilatum has wide swings in population size.[1] When concentrations rise, algal blooms occur and fish can be killed by the ichthyotoxin, goniodomin A identified in both A. monilatum and A. pseudogoniaulax. Secondary toxic substances produced by this species include saxitoxins and gonyautoxins.[2][4] Toxic red tides caused by this species have caused large fish kills off the coasts of Texas, Florida and Venezuela.[2] This dinoflagellate does not cause mortality in adult shellfish but does reduce nutritional uptake as well as increasing mortality in larvae.[4]
References
Guiry, M.D.; Guiry, G.M. "Alexandrium monilatum". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.
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Alexandrium monilatum: Brief Summary
provided by wikipedia EN
Alexandrium monilatum is a species of armored, photosynthetic, marine dinoflagellates. It produces toxins that, when present in high concentrations as "red tides", can kill fish and reduce growth rates of shellfish.
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- cc-by-sa-3.0
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- Wikipedia authors and editors
