Morphological and genetic evidence that the cyanobacterium Lyngbya wollei (Farlow ex Gomont) Speziale and Dyck encompasses at least two species

Institute of Marine Sciences, University of North Carolina at Chapel Hill, 3431 Arendell Street, Morehead City, NC 28557, United States; Center for Coastal Fisheries and Habitat Research, National Ocean Service, NOAA, 101 Pivers Island Road, Beaufort, North Carolina 28516-9722, United States

^* To whom correspondence should be addressed. Email: jjoyner{at}unc.edu.

	Abstract

Dense blooms of the cyanobacterium, Lyngbya wollei, are increasingly responsible for declining water quality and habitat degradation in numerous springs, rivers, and reservoirs. This research represents the first molecular phylogenetic analysis of "Lyngbya wollei" in comparison with traditional morphological characterization of this species. Specimens were collected from several springs in Florida and a reservoir in North Carolina, USA. A segment of the small subunit (SSU) rRNA and nifH genes were PCR amplified, cloned, and sequenced. The phylogenetic analysis of the SSU rRNA gene revealed sequences that fell into three distinct subclusters, each with >97% sequence similarity. These were designated operational taxonomic units OTU1, OTU2, and OTU3. Similarly, the nifH sequences fell into three distinct subclusters labeled: S1, S2, and S3. When either bulk samples or individual filaments were analyzed, OTU1 was recovered with S1, OTU2 with S2, and OTU3 with S3. The coherence between the three SSU and nifH subclusters was consistent with genetically distinct strains or species. Cells associated with subclusters OTU3 and S3 were significantly wider and longer than those of other subclusters. The combined molecular and morphological data indicate that the L. wollei commonly identified in the literature represents two or possibly more species. Springs containing OTU3 and S3 demonstrated lower ion concentrations than other collection sites. Geographical locations of Lyngbya subclusters did not correlate with residual dissolved inorganic nitrogen or phosphorus concentrations. This study emphasizes the need to complement traditional identification with molecular characterization to more definitively detect and characterize harmful cyanobacterial species or strains.