Pseudo-nitzschia pseudodelicatissima (Hasle) Hasle emend. Lundholm, Hasle & Moestrup
Pseudo-nitzschia pseudodelicatissima is a domoic-acid-producing, pennate diatom (Lundholm et al. 1997).
Pseudo-nitzschia pseudodelicatissima has caused domoic acid contamination of shellfish in Atlantic Canada, resulting in closure of shellfish beds. Lectin-binding probes were not able to distinguish between New Zealand-derived cultures of P. delicatissima and P. pseudodelicatissima (Rhodes 1998a). Whole cell fluorescent LSU targeted probes have been developed for identifying P. pseudodelicatissima cultures from the west coast of the United States (Miller & Scholin 1996). These probes were used to develop whole cell and sandwich hybridization methods for detection of P. pseudodelicatissima in natural samples at near real time (Scholin et al. 1997, Miller & Scholin 1998). The probe designed to identify P. pseudodelicatissima on the west coast of the United States did not work on P. pseudodelicatissima in the Gulf of Mexico (Parsons et al. 1999). This could be because of high genetic variability within the P. pseudodelicatissima group, which was later divided into additional species based on morphological and molecular analysis (Lundholm et al. 2003). Multiple probes based on clone libraries have been used to identify P. pseudodelicatissima in the Gulf of Naples (McDonald et al. 2007). P. pseudodelicatissima isolates from Tasmanian and Victorian coastal waters were consistently non-toxic (Hallegraeff 1994).
From Lundholm et al. 2003: Overlapping cells in colonies. Cells linear in valve view, tapering part near the tips very short; in girdle view cells are linear to lanceolate. Transapical axis 0.9-1.6 microns, apical axis 54-87 microns. Eccentric raphe divided in the middle by central nodule. Fibulae regularly spaced, 20-25 (28) in 10 microns, interstriae 36-43 in 10 microns. Striae with one row of oval to square poroids, 5-6 poroids in 1 micron. Hymen of poroids divided into two large parts. Valve mantle structured as valve face, 1 (2) poroid high. Cingulum with three open bands, containing one row of 48-55 poroids in 10 microns, each poroid hymen sometimes further subdivided.
Growth rates of P. pseudodelicatissima cultures in the laboratory are affected by salinity and temperature. The optimum salinity for growth in Danish isolates of P. pseudodelicatissima was 25 at all temperatures tested (2-25 degrees C). No growth was recorded at 5 and 10 salinity (Lundholm et al. 1997). Growth rates increased with temperature. No growth was observed at 2 and 5 degrees C. The lower temperature limit for growth depended on salinity (Lundholm et al. 1997). Canadian isolates of P. pseudodelicatissima can produce domoic acid at 0.007 and 0.0098 pg per cell in the laboratory (Martin et al. 1990).
Pseudo-nitzschia pseudodelicatissima can be found in coastal and oceanic, tropical and temperate waters. It is abundant on the west coast of the United States in the autumn (Fryxell et al. 1997), in the Juan de Fuca eddy (Marchetti et al. 2004) and in the Skagerrak from June-December (Hasle et al. 1996). It is a major bloom former in Australian waters (Hallegraeff 1994). Both toxic and non-toxic varieties are present in the Bay of Fundy, Canada (Kaczmarska et al. 2005). From Hasle 2002: Atlantic: Resolute Bay, Canadian Arctic, ca 75°N (Quillfeldt von, 1996) to Argentinean coastal waters, ca 38°S ( Ferrario et al., 1999), including Barents Sea, northeast of Greenland ( Quillfeldt von, 1996), Denmark Strait (Hasle, 1965), Norwegian Sea, Shetland, Norwegian coastal waters and Skagerrak ( Hasle and Hasle), Icelandic (unpublished observations), Danish ( Lundholm et al., 1994), Irish ( Cusack et al., 2000) and Portuguese ( Hasle, 1965) coastal waters, Kiel Bay ( Hansen and Horstmann, 1993), English Channel (unpublished observations), Galicia, northwest Spain ( Miguez et al., 1996), Portuguese waters ( Moita and Vilarinho, 1999), off west coast of North Africa, Gulf of Naples and Adriatic Sea ( Hasle, 1965); Hudson Strait ( Hasle, 1965), Gulf of St. Lawrence ( Bérard-Therriault et al., 1999), Bay of Fundy ( Martin et al., 1990), Chesapeake Bay, MD (unpublished observations), Gulf of Mexico ( Parsons et al., 1999), Yucatan shelf ( Licea et al., 2000), southern Brazil ( Odebrecht and Villac). Pacific: Herschel Island, Beaufort Sea, 69°38′N (Hasle, 1965) to Chile, 53°13′S (Rivera, 1985), including off Washington coast and Coos Bay, OR ( Fryxell et al., 1997), Berkeley marina, CA ( Skov et al., 1999), Monterey Bay and Newport, CA (Villac et al., 1993), La Jolla, CA ( Lange et al., 1994), Mexican Pacific coast (Licea et al., 2000), Quetalco, Chile ( Hasle, 1965); Sakhalin Island and Sea of Japan ( Orlova et al., 2000), Ofunato and Atsumi Bays, Japan ( Takano and Kuroki, 1977), Xiamen, East China Sea ( Qi et al., 1994), Chilean waters ( Hasle, 1965), pp. 1–45.Hasle, 1965), Victorian, New South Wales and Tasmanian waters, Australia (Hallegraeff and Lapworth), New Zealand waters ( Rhodes et al., 1998).
Nitrate and Nitrite concentrations play an important role in the abundance of Pseudo-nitzschia pseudodelicatissima in the Bay of Fundy, Canada (Kaczmarska et al. 2007). P. pseudodelicatissima abundance is positively correlated with nitrate concentration in the Bay of Fundy, Canada (Kaczmarska et al. 2007). Blooms of P. pseudodelicatissima in the inner Oslofjord constitute a major food source for Protoperidinium spp. (Kjaeret et al. 2000). P. pseudodelicatissima can occur throughout the year in the Bay of Fundy and is most abundant in September (Martin et al. 1993). Domoic acid levels in plankton tows were 3.5-3.9 micrograms per gram and maximum cell abundances were 1.2 million cells per Liter (Martin et al. 1990; Martin et al. 1993).
Pseudo-nitzschia pseudodelicatissima can reproduce asexually by cell division and sexually to restore cell size (Davidovich & Bates 1998).