Prorocentrum balticum

P. balticum is a planktonic species. It is a neritic and oceanic species with world-wide distribution (Dodge 1975; Dodge 1982; Steidinger & Tangen 1996). Cells are active swimmers.
This species has been reported to form red tides in many parts of the world (see Lassus 1988). Many blooms have occurred in brackish water habitats (Tangen 1980; Zotter 1979; Edler et al. 1984) confirming Braarud's (1951) earlier growth experiments that revealed P. balticum's highest growth rates were at low salinities (10-15 o/oo).

Prorocentrum balticum is commonly found in marine waters all over the world: cosmopolitan in cold temperate to tropical waters (Dodge 1975; 1982; Steidinger & Tangen 1996).

Prorocentrum balticum is a photosynthetic species with a round nucleus situated posteriorly (Dodge 1975; Dodge 1982; Toriumi 1980).

Holotype: Exuviaella baltica Lohmann, 1908: 265, plate 17, fig. 1a, b
Type Locality: unknown

P. balticum reproduces asexually by binary fission.

P. balticum is not easily distinguished from P. minimum and a critical assessment of its taxonomic status is still needed. Both are small species, valves covered with small spines, and periflagellar areas are relatively small with two pores. P. balticum is distinguished by its small size, its almost spherical shape (Toriumi 1980), and its two minute apical projections (Faust et al. 1999).
Because of its small size, records of P. balticum may actually include closely related, but undescribed species (Steidinger & Tangen 1996).

Prorocentrum balticum is an armoured, marine, planktonic, bloom-forming dinoflagellate species. This cosmopolitan species is commonly found in cold temperate to tropical waters world-wide.

Prorocentrum pomoideum Bursa, 1959
Exuviaella aequatorialis Hasle, 1960

P. balticum is a bivalvate species often observed in valve view. Cells are small (less than 20 µm in diameter), and round to ovoid in valve view (Figs. 1, 2, 4), with two minute and distinct apical projections (Figs. 1, 3, 4). Although cells are nearly spherical, some have broad shoulders. Thecal valves are covered with many tiny interconnected spines (Figs. 1-4) which form narrow transverse rows on the intercalary band (Fig. 1). Many scattered rimmed pores are present on the cell surface (Fig. 2) (Dodge 1975; 1982; Toriumi 1980; Steidinger & Tangen 1996; Faust et al. 1999).
Two minute apical spines (Figs. 1, 3, 4) border the relatively small periflagellar area. The periflagellar pores are different sized (Fig. 3) (Dodge 1975; Toriumi 1980; Steidinger & Tangen 1996; Faust et al. 1999).

Although toxicity in P. balticum has never been confirmed, it has been associated with toxic red tides (Silva 1956; Silva 1963; Numann 1957). Steidinger (1979) regards it as a questionable toxic species.