The reproductive stages of Dermocarpella gardneri and D. stellata, which have been reported only once, are described. Formation of baeocytes occurs by cellular divisions that are parallel to the substratum, followed by a series of anticlinal radial divisions. In some cases in D. gardneri, the superior cell, resulting from the first division parallel to the substratum, is liberated prior to radial divisions, and these probably represent the ‘macrogonidia’ originally described by Lemmermann for D. hemisphaerica. The baeocytes are released through a circular apical pore, which develops after the formation of a papilla that eventually dissolves to form a pore.

There is increasing evidence that bacterial–algal interactions play a role in Harmful Algal Bloom (HAB) ecology. Bacteria that are associated with bloom-forming algal species, specifically toxic dinoflagellate algae, have been implicated in the production and biotransformation of paralytic shellfish toxins (PSTs). To clarify the role that these bacteria may play in the production of PSTs, it is desirable to identify and localize the bacteria associated with the dinoflagellates and enumerate them during the course of the algal blooms that the toxic dinoflagellates produce. Because 16S rRNA-targeted probes offer the possibility of both, we previously made and tested probes for some putatively toxigenic bacteria isolated from cultures of the PSP-related dinoflagellates Alexandrium tamarense, A. affine and A. lusitanicum. The bacteria isolated from the dinoflagellates belong primarily to the alpha-proteobacterial group of Roseobacter and the gamma-proteobacterial group of Alteromonas. Here, we report the successful application of these probes to Lugol's-fixed seawater samples. We detected these bacteria in high numbers in the water column when Alexandrium spp. were both present and absent, and during periods when mussels contained PSTs.

Immunofluorescence assays using polyclonal and preadsorbed antibodies as well as FITC-labelled lectins were employed to characterize two morphospecies of the cyanophytes Pseudanabaena catenata and P. planctonica from laboratory cultures isolated from two reservoirs in Spain and one in Denmark. Binding of both antibodies and lectins was unaffected by phase of the cell division cycle, growth phase and environmental factors such as culture medium, light or temperature. Good-quality polyclonal antibodies were obtained for several strains of both morphospecies. As expected, different morphospecies from the same location do not share common antigens while strains of the same morphospecies grown in different reservoirs do share most of their surface antigens. However, P. catenata grown at La Pinilla (Spain) does not share common antigens with P. catenata from Bastrup (Denmark). Geographical barriers, in this case, seem to play an important role in determining surface antigen diversity. Similar results are obtained when lectins are used, and some lectins are found to be useful tools for differentiating clones of the same morphospecies. From a genetic point of view there may be no clear species boundary for some morphospecies of cyanobacteria. A ‘fuzzy species’ concept, i.e. a species that belongs in part to more than one species or has characteristics of more than one species, is speculatively considered to explain genospecies boundaries of cyanobacteria.

The total DNA of ten isolates of different chlorophycean algal genera was extracted according to a protocol for the extraction of fungal DNA. Algal DNA was digested with up to ten different restriction endonucleases. In Southern hybridizations, DNA was probed with a digoxigenin-labelled 440 base pair (bp) fragment of bacteriophage M13 containing a repetitive sequence with a 15 bp core repeat. Stringency conditions for the detection of banding patterns in algae of different genera are described. The stability of DNA fingerprints of subcultures of the same isolate was investigated. DNA fingerprints of isolates of the genera Chlorella, Klebsormidium and Stichococcus were compared. The results show that the M13 minisatellite probe can be used to detect DNA fingerprints in chlorophyte algae of different genera and to differentiate isolates of the same species.