Analytical detection of parasite infection of Dinophysis norvegica using FISH probes

Parasites of the genus Amoebophrya infect several freelivingdinoflagellates, including harmful species. Whereas advanced infection can be easily detected, earlier stages of infection are more difficult to establish. rRNA-based fluorescent in situ hybridisation (FISH) probes specific to Amoebophrya sp. infecting Dinophysis norvegica in the Baltic Sea were combined with 4’,6-diamidino-2-phenylindole (DAPI) staining to study this host-parasite system in a series of samples collected over a 24h period in August 1998. Small forms of Amoebophrya sp. (6–8ìm) within D. norvegica, undetected by DAPI staining, were revealed by the FISH probe. As a result, the average infection estimated by FISH (7.8%) was 6.5 times higher than the estimate based on DAPI alone. Multiple infections were observedin 75% of the infected D. norvegica cells, indicating that this may be a common feature in this host-parasite system. FISH probes therefore provide a valuable tool to assess parasite infection of dinoflagellates in fieldsamples

Ecological Aspects of Harmful Algal In Situ Population Growth Rates

14 pages, 4 figures, 2 tablesPeer reviewe

Harmful Algal Blooms and the Importance of Understanding Their Ecology and Oceanography

17 pages, 1 figure, 1 tableOver the decades of the 1980s and 1990s, as the expansion in harmful algal blooms (HABs) was gaining recognition (e.g., Anderson 1989; Hallegraeff 1993; GEOHAB 1998; Smayda 2002), no longer was it sufficient to study bloom events in isolation; many countries were facing a bewildering array of impacts caused by species not previously known or recognized in those regions. The complexity of the HAB problem, its causative factors, and the impacts HABs have on the environment were becoming well characterized. The benefits of collaborative, cooperative, and comparative studies on HABs were recognized to advance the understanding of this phenomenon and to provide scientific guidance to managers. The aim of this chapter is to introduce several aspects of this complex phenomenon, and why an understanding of ecology and oceanography of HAB species and their associated events is so important. This chapter also briefly introduces the effects of global changes in nutrients and climate that are developed more fully in subsequent chapters [see Chap. 4, Glibert et al. (2018b), and Chap. 5, Wells and Karlson (2018)], as well as a number of concepts relating to the adaptive strategies of HABs which help to explain why they are so successful in environments subject to many anthropogenic changesPeer reviewe