Occurrence of Diatom – Diazotrophic association in the coastal surface waters of south Andaman, India

• Published in: Symbiosis (Philadelphia, Pa.) Vol. 76; no. 3; pp. 293 - 302
• Main Authors: Manjumol, C. C., Linoy Libini, C., Albert Idu, K. A., Mohamed, K. S., Kripa, V.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-11-2018; Springer Nature B.V
• Subjects: Bacillariophyceae; Biomedical and Life Sciences; Coastal waters; Developmental Biology; Ecology; Evolutionary Biology; Hemiaulus membranaceus; Heterocysts; Life Sciences; Microbiology; Plankton; Plant Sciences; Protozoa; Rhizosolenia clevei; Rhizosolenia cylindrus; Rhizosolenia hebetata; Trichomes; Vegetative cells; India; Diazotrophy; Cyanobacteria
• ISSN: 0334-5114; 1878-7665
• DOI: 10.1007/s13199-018-0559-y

The heterocystous cyanobacterium
Richelia intracellularis
Schmidt 1901 is well known for its capability to fix atmospheric nitrogen (N
2
) in oligotrophic waters. Symbiotic associations of
Richelia intracellularis
with the diatoms
Rhizosolenia hebetata, Rhizosolenia clevei, Rhizosolenia cylindrus
and
Hemiaulus membranaceus
is reported for the first time from the coastal waters of South Andaman, India. In these the symbiotic associations, variations were observed in the number of vegetative cells, trichomes, and the shape of the heterocysts. The highest number of trichomes was observed in
Rhizosolenia clevei
(14) per host. The trichomes consisted of 9–10 vegetative cells and a spherical heterocyst that was orientiated toward one end of the host diatom cell. In
Rhizosolenia hebetata
, three trichomes of
Richelia intracellularis
were present, one trichome at one end with 7–8 vegetative cells and two trichomes at the other end. In
Rhizosolenia cylindrus
, two trichomes of
Richelia
were observed, with a spherical heterocyst and 5–6 vegetative cells. An association between
Hemiaulus membranaceus and Richelia intracellularis
was also observed but with less frequency. Trichomes were observed in the centre of the diatom. By using the cell-specific rates, the amount of new N provided by the Diatom-Diazotrophic Associations was estimated. This is the first record of a symbiotic association of
Richelia
in diatoms from Andaman coastal waters.