James Trice, III - Protistan Ecology Lab
North Carolina Central University, Durham, NC
Protist symbolize a vast assemblage of essentially unicellular organisms, in which a single cell is capable of all life functions executed in higher organisms by specialized organs (Lom and Dykova' 1992). There are two main types of nutrition in protists, autotroph and heterotroph. In autotrophic forms, organic substances are provided by photosynthesis while heterotrophic protozoa depend on organic substances including animals for nutrition. In addition, some protists are mixotrophs and can be both autotrophic and heterotrophic at the same time. In the class Dinoflagellida, 60% of the species are photosynthetic, being among the most important primary producers in the oceans, while the others are non-photosynthetic or parasitic. Large groups of dinoflagellates are adapted to a parasitic way of life. Most live as ectoparasites, while others are intracellular parasites. Many species live on or in various aquatic animals including fishes.
The one parasitic dinoflagellate I will focus on is Crepidoodinium cyprinodontum. C. Cyprinodontum has an elongated trophont which is covered by a theca without thecal plates. The dinoflagellate holds on to its host with a hold fast which is split in an irregular way. The holdfast forms many projections sometimes exceeding 200µm. While on the host, green dots are the appearance of C. cyprinodontum on the gills, when viewed under a stereomicroscope. Thus far, only five species of fish in the USA have been found to be infected by Crepidoodinium cyprinodontum on their gills. These species include, Fundulus majalis, F. heteroclitus, Cyprinodon variegatus, Lucania para and Fundulus lucia (Lawler1967; Lom, Rohde and Dykova 1993). Furthermore, a new species, Crepidoodinium australe has been found on the gills of Sillago ciliata (sand whiting) off the coast of New South Wales, Australia (Lom, Rohde and Dykova 1993).
Scientist do know that C. Cyprinodontum is photosynthetic and lives in estuarine water, however they do not know if it is mixotrophic. Due to the lack of study, there is a vast amount of research that needs to take place. Nobody knows if Crepidoodinium cyprinodontum is a commensal or parasite. Also, we don't know the ecology or the oxygen, temperature and pH levels this organism lives in or their geographical locations. However we do know C. cyprinodontum is found in water with salinities of 20â?° to marine but nobody knows the relationship of parasitism to salinity, fish's size or age. are at a high activity rate or if the fish's size and age. Most important, nobody knows why Crepidoodinium lives on certain species of fish and not others. I hope to answer all of these questions however time is limited and personally I will focus on how the age of the fish affects the prevalence of C. cyprinodontum. I will also attempt to develop an efficient technique for removal of Crepidoodinium cyprinodontum from fish gills without seriously harming the host.
Funding provided by NOAA/Sea Grant