Gulf of Mexico Science Volume 5 Number 1 Number 1 Article 1 10-1981 Causative Analysis on a Nearshore Bloom of Oscillatoria erythraea (trichodesmium) in the Northern Gulf of Mexico Lionel Eleuterius Gulf Coast Research Laboratory Harriet Perry Gulf Coast Research Laboratory Charles Eleuterius Gulf Coast Research Laboratory James Warren Gulf Coast Research Laboratory John Caldwell Gulf Coast Research Laboratory Follow this and additional works at: https://aquila.usm.edu/goms DOI: 10.18785/negs.0501.01 Recommended Citation Eleuterius, L., H. Perry, C. Eleuterius, J. Warren and J. Caldwell. 1981. Causative Analysis on a Nearshore Bloom of Oscillatoria erythraea (trichodesmium) in the Northern Gulf of Mexico. Northeast Gulf Science 5 (1). Retrieved from https://aquila.usm.edu/goms/vol5/iss1/1 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf of Mexico Science by an authorized editor of The Aquila Digital Community. For more information, please contact [email protected]. Eleuterius et al.: Causative Analysis on a Nearshore Bloom of Oscillatoria erythraea Northeast Gulf Science Vol5, No.1, p. 1-11 October 1981 CAUSATIVE ANALYSIS ON A NEARSHORE BLOOM OF Oscillator/a erythraea (TRICHODESMIUM) IN THE NORTHERN GULF OF MEXICO Lionel Eleuterius, Harriet Perry, Charles Eleuterius James Warren, and John Caldwell Gulf Coast Research Laboratory Ocean Springs, MS 39564 ABSTRACT: Physical, chemical, and biological characteristics which preceded and caused a bloom of Osclllatorla erythraea commonly known as trlchodesmlum In coastal waters of Mississippi and adjacent waters of the Gulf of Mexico are described. This Is the first report of the blue-green alga occurring in high density near the mainland and In a predominantly estuarine area of the northern Gulf of Mexico. Environmental conditions Immediately prior to and during the bloom were characterized by low rainfall, calm sea, a homogeneous water column, low nitrate-nitrogen (0-5 N03-N pg-atom/1), no measurable nitrite-nitrogen (0 N02-N pg-atom/ I), high water temperatures (29-30° C), high salinity (270/100), and a basic pH (8.3 to 8.4). Total phosphorus and orthophosphate& were also low prior to the bloom (0.1 P pg­ atom/1), but increased slightly during the later stages of the bloom (0.7 to 1.5 P pg-atom/ 1). The alga disappeared with the return of well-mixed sea water, lower salinity, lower temperature and acidic pH, and an increase in combined nitrogen content. Osclllatorla erythraea occurred in bundles of 10 to 25 trichomes or as a single filament, ranging from 8 to 15pm In diameter and about 0.3 mm in length. The alga occurred in patches with the greatest concentration near the surface. Some entrapment of zooplankton in the dense algal mass was observed, but most of the zooplankton was diverse and unharmed. Harmful effects of the algal bloom on larger animals were not observed nor believed to have occurred. ' Blooms of the planktonf6,blue-green Antarctic waters. alga Oscillatoria erythraea (Ehrenberg) Experimental evidence indicates that Kutzing commonly known as tricho­ trichodesmium is capable of nitrogen desmium are common in tropical seas fixation (Dugdale et a/., 1961; Dugdale, around the world. This organism has et a/., 1964; Goering et a/., 1966; been reported frequently from the Indian Ramamurthy and Krishnamurthy, 1967; Ocean, especially the Bay of Bengal, the Carpenter, 1973; Taylor, et a/., 1973; Red and Arabian seas and the tropical Carpenter and McCarthy, 1975). Stewart Atlantic Ocean including the coastal and Bottomly (1976) review the literature waters of South America, the Sargasso and point out that many morphological Sea and the Strait of Florida (Moseley, types of blue-green algae show nitro- 1879; Brongersma-Sanders, 1957; 'genase activity. In some regions tricho­ Dugdale, eta/., 1961; Dugdaleeta/., 1964; desmium blooms become so intense and Sieburth and Conover, 1965; Goering, et widespread that they may make a major a/., 1966; Qasim, 1970; Yentsch, et a/., contribution to the nitrogen budget of the 1972; Carpenter, 1973). Blooms in the sea (Eppley and Thomas, 1969; Thomas, Pacific Ocean have been reported by 1971; Carpenter, 1973; Carpenter and Wood (1965) and Bowman and Lancaster Price, 1976). Trichodesmium may be de­ (1965).There are fewer reports of the alga trimental to certain plants and animals from temperate seas, indicating that (Bowman and Lancaster, 1965; Qasim, blooms occur less frequently northward 1970), while favoring the growth of others and southward from the tropics. Farran (Calef and Grive, 1966). Ramamurthy (1932) found trichodesmium off the (1970) reported no fish mortality in coast of Ireland and Wood (1965) reports dense concentrations of the alga, how­ it south of New Zealand and even in ever the diversity of fishes was decreased, Published by The Aquila Digital Community, 1981 1 1 Gulf of Mexico Science, Vol. 5 [1981], No. 1, Art. 1 2 L. Eleuterius, H. Perry, C. Eleuterius, J. Warren, and J. Caldwell f· suggesting bloom avoidance by certain initiated on 13 August 1974, approximate­ species. He also reported that 80 to 90% ly three days after initial reports of the of the gut content, of fish taken within the bloom, to determine its extent and in­ bloom, contained trichodesmium. tensity. Clarke-Bumpus samplers fitted There are no detailed reports on with 157 pm mesh nets were used for blooms of trichodesmium of temperate plankton collections at the surface and seas, especially nearshore, estuarine bottom. Tows were made at a constant areas. Thomas (1960) and Simmons and speed for intervals of ten minutes. The Thomas (1962) report trichodesmium tow interval for surface samples taken in from the eastern Mississippi Delta. the nearshore waters of Ship Island was Gunter et a/., 1948; Curl (1959); Humm three minutes, because of the great den­ and Caylor (1957); and Oppenheimer sity of the alga in the water column. Many (1970) report it from off the Florida, Mis­ samples were also taken from the surface sissippi and Texas coasts, respectively. and subsurface waters by bucket and Davis (1954) and Van Baalen and Brown subsamples made on a volume basis. (1969) report it from the Gulf of Mexico. Samples were preserved in the field in a Trichodesmium is known to the present 5% solution of formalin buffered with authors to be an ephemeral component of methenamine. the Mississippi Sound phytoplankton. Although hydrological data were However, some biological and ecological taken with each plankton sample, the characteristics of a large bloom of trich­ description of the physical conditions odesmium occurring in Mississippi occurring during the bloom is based on Sound and in the immediately adjacent unpublished data from a concurrent waters of the Gulf of Mexic.o during the oceanographic survey of Mississippi \ late summer of 1974 are evaluated and Sound described by Eleuterius (1976a,). analyzed here to determine the cause of Conductivity, temperature; pH and dis­ the bloom. solved oxygen were measured in situ by a Mississippi Sound is separated from Martek water quality analyzer with an ac­ the Gulf of Mexico by a chain of barrier curacy of± 0.5° C. Conductivity was later islands, which lie from 12.9 to 19.3 kilo­ converted to salinity in ppt by an empiri­ meters (8 to 12 miles) off the mainland cal relationship. Transparency was de­ shore. Four rivers discharge fresh water termined by Spectronic 20 Perkin-Elmer into Mississippi Sound from the north and Spectrophotometer set at a wavelength of sea water enters Mississippi Sound 580 nanometers (nm). Distilled water was through the island passes; thus the water used as a standard and the instrument generally exhibits an increasing salinity adjusted to 100%. A sample of seawater g.~~c;l.ient from the mainland toward the was read as a percentage of light trans­ sea.~.Additionally, Mississippi Sound is mitted. Concentrations of the inorganic influenced by freshwater discharge from nitrogenous compounds, nitrate, nitrite Mobile Bay on the east and occasionally, and ammonium, were determined from during flood years, by the Bonnet Carre unfiltered seawater using standard sea Spillway of the Mississippi River on the water methods (Strickland and Parsons, west. 1972). Total phosphorus and orthophos­ phate of unfiltered seawater were deter­ METHODS AND MATERIALS mined using methods 11.3 and method 11.2.1 described by Strickland and Par­ Field procedure sons (1972), with no appreciable dif­ https://aquila.usm.edu/goms/vol5/iss1/1Surveys by boat and airplane were ferences found using filtered and unfilter- DOI: 10.18785/negs.0501.01 2 ----- - ---------- Eleuterius et al.: Causative Analysis on a Nearshore Bloom of Oscillatoria erythraea Estuarine Trichodesmium bloom 3 ed seawater samples. Regardless of the surface, and the air was permeated by a presence of phytoplankton or detritus in strong chlorine or iodine-like odor. Some the samples, for purposes of our analysis fishermen discribed the odor as that of it can only be regarded as an estimate or freshly-mowed grass or fresh tea. The approximation and not an absolute value scum formed great rafts on the water of the total nutrient budget of the sea­ surface and patches of dark brown or water. Sample analyses were carried out reddish water without rafts on the surface consistently and are the only chemical were easily delineated by aerial flights on data available which correspond to the 16 August. development of the bloom. Algal samples The sea was very calm during the were taken near Horn and Ship Islands by week prior to the bloom, the sunshine Gulf Coast Research Laboratory staff brilliant, and a gentle breeze prevailed. personnel and biologists of the Gulf Is­ These environmental conditions ac­ lands National Seashore, U.S. Park companied the bloom for about a week Service. after the onset, the bloom probably reaching peak development on the fourth Laboratory procedure or fifth day after it was first observed.