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 L. wollei in comparison with the traditional morphological characterization of this species. Specimens were collected from several springs in Florida and a reservoir in North Carolina. Segments 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 unit 1 (OTU1), OTU2, and OTU3. Similarly, the nifH sequences fell into three distinct subclusters named S1, S2, and S3. When either bulk samples or individual filaments were analyzed, we recovered OTU1 with S1, OTU2 with S2, and OTU3 with S3. The coherence between the three SSU rRNA gene 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 associated with other subclusters. The combined molecular and morphological data indicate that the species commonly identified as L. wollei 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.

During July 2006, 2 distinctly different harmful algal blooms (HABs), one dominated by the pelagic red tide dinoflagellates Karenia spp. and the other by the benthic cyanobacterium Lyngbya majuscula, occurred simultaneously in the coastal embayments surrounding Sanibel and Captiva Islands, Florida, USA. The co-occurring HABs were investigated using in situ bioassays with additions of nitrogen (N) and phosphorus (P) alone and in combination to assess nutrient controls of these 'dueling' toxin-producing species. Photosynthetic, biomass (chlorophyll a), and (in L. majuscula) nitrogen fixation responses to nutrient enrichment were examined over 4 d. Primary productivity in Karenia spp. was consistently stimulated by N additions, while P additions failed to show stimulation. When added in combination with N, P did not lead to additional stimulation above N alone. Similar patterns of chlorophyll a stimulation were observed. These patterns were observed at 2 d, after which the cells fell out of suspension. Nutrient stimulation of L. majuscula metabolic activities as well as biomass production was smaller and much slower, relative to controls, than responses observed in Karenia spp. After the demise of Karenia spp., L. majuscula was able to continue utilizing subsequent nutrient additions, and it responded most strongly to the N + P additions after 4 d. This study confirms previous estuarine and coastal studies that indicated that when non-N 2 -fixing HABs co-occur with N 2 -fixing cyanobacterial HAB species, both N and P inputs need to be carefully considered and, in all likelihood, controlled.KEY WORDS: Lyngbya · Karenia · Charlotte Harbor · Sanibel and Captiva Islands · Florida · Blooms · Nutrients Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 371: [143][144][145][146][147][148][149][150][151][152][153] 2008 species include the Florida red tide dinoflagellate Karenia brevis (Steidinger et al. 1998, Steidinger 2002, Vargo et al. 2008 and, among the cyanobacteria, the planktonic genus Trichodesmium and the benthic genus Lyngbya. While the origin of these bloomforming taxa (i.e. offshore, nearshore, estuarine) can vary substantially, there is good agreement that when these bloom species encounter nutrient-enriched conditions, growth and bloom intensity of many of these taxa may be enhanced (Paerl 1988, Lapointe 1997, Elmgren & Larsson 2001, Paerl & Fulton 2006. Accordingly, there is a great deal of concern about coastal nutrient enrichment associated with rapid rates of coastal development in Florida and elsewhere.During July 2006, 2 taxonomically and ecologically distinct harmful algal blooms (HABs), one comprised of planktonic Florida red tide dinoflagellates Karenia spp. and the other of the benthic filamentous cyanobacterium Lyngbya majuscula, co-occurred in the coastal embayments of Sanibel and Captiva Islands, on Florida's southwest coast (see Fig. 1). Both genera have been implicated in regional water quality, fisheries habitat, and human health probl...

Harmful blooms of the benthic cyanobacteria Lyngbya spp. are increasing in coastal marine habitats. Nutrient enrichment has been implicated in bloom formation; however, the effects of nutrient enrichment on secondary metabolite concentrations and the resulting palatability of Lyngbya spp. are not known. Using nutrient bioassays, we examined the effects of nitrogen (N), phosphorus (P) and chelated iron (Fe) on growth and secondary metabolite concentration in Lyngbya sp. collected from reefs in Broward County, Florida. The consequences of these nutrient additions on feeding behavior of a major specialist opisthobranch grazer, Stylocheilus striatus, were examined. Chelated Fe additions (+FeEDTA) significantly increased Lyngbya sp. growth, while additions of N, P and chelated Fe combined (+All) resulted in significantly lower concentrations of microcolin A than in the control. Overall, there was a negative correlation between growth and total concentrations of microcolins A and B. When crude extracts from the control, +FeEDTA and +All treatments of the Lyngbya sp. bioassay were offered to S. striatus in artificial food, they consumed greater quantities of the control and +FeEDTA treatments than the +All. These results provide the first evidence that changes in nutrient availability can affect secondary metabolite concentrations in marine Lyngbya spp. and support previous studies that show that Fe can stimulate growth in benthic marine cyanobacteria. This study also demonstrates quantifiable changes in feeding behavior by a specialist grazer in response to changes in the nutrient conditions under which Lyngbya sp. grows and underscores the need to consider secondary metabolite concentrations, and their effect on grazers, when managing harmful algal blooms.

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