The genus Pseudo-nitzschia (Bacillariophyceae) in New Zealand: analysis of the last decade's monitoring data

Figures & data

Table 1 Domoic acid (DA) production determined for Pseudo-nitzschia isolates from sites throughout New Zealand (analysed by LC-MS or HPLC-UV).

Species	First New Zealand record	Range of DA (pg cell^−1)	Geographical distribution (New Zealand)
P. americana	1994	0	Hauraki Gulf, Marlborough Sounds, Canterbury, Big Glory Bay
P. australis	1993	0–35	Northland, Hauraki Gulf, Marlborough Sounds, Big Glory Bay
P. caciantha	2005	0	Marlborough Sounds, Canterbury, Caroline Bay (Timaru),
P. calliantha	2005	0	Marlborough Sounds, Canterbury
P. cuspidata	2005	0	Marlborough Sounds
P. delicatissima	1996	0.1	Marlborough Sounds, Big Glory Bay
P. fraudulenta	1996	0–0.03	Northland, Canterbury, Marlborough Sounds, Big Glory Bay
P. cf. heimii	1996	0	Northland, Marlborough Sounds
P. multiseries	1997	0.8	Golden Bay
P. multistriata	1997	0–1.6	Northland, Hauraki Gulf, Bay of Plenty; Golden Bay; Marlborough Sounds
P. pseudodelicatissima	1996	0.12	Marlborough Sounds, Caroline Bay, Big Glory Bay
P. pungens	1993	0–0.5	Poverty Bay, Golden Bay, Marlborough Sounds; Canterbury, Big Glory Bay
P. turgidula	1996	0.03	Bay of Plenty

Figure 1 Maps of New Zealand and the Marlborough Sounds highlighting the sites referenced in this study. Marlborough Sounds strata boundaries used in GLM analysis are shown for: Pelorus Sound, inner (inp), mid (midp) and outer (outp); Queen Charlotte Sound, inner (inq) and outer (outq); Port Underwood (pu); Port Gore (pg).

Figure 2 Seasonal occurrence of Pseudo-nitzschia in New Zealand. A, Plot of season as a predictor variable against the diatom genus, Pseudo-nitzschia. (Cells l⁻¹ in log scale; horizontal lines are the max./min.; circles show outlier data, determined as 1.5 times the interquartile range). The differences are significant (P<0.001; Hollander & Wolfe 1973). B, Percentage of samples from New Zealand's coastal waters in which Pseudo-nitzschia exceeded the trigger level (10×10⁴ cells l⁻¹) by site and season, 2000–11. Seasonal graphs clockwise from top left are: summer (Dec–Feb), autumn (Mar–May), winter (Jun–Aug), spring (Sep–Nov).

Figure 3 Pseudo-nitzschia species composition in New Zealand's coastal waters, January 2005–August 2011. Data were only obtained from samples in which Pseudo-nitzschia cell concentrations occurred > 50×10³ cells l⁻¹. Results were derived from actual cell counts of fluorescent in situ hybridisation (FISH) assays of 1827 seawater samples. P. pseudodelicatissima refers to a grouping of species, including P. caciantha, P. calliantha, P. cuspidata and P. pseudodelicatissima itself.

Table 2 Comparison of morphometric data obtained for four New Zealand isolates of Pseudo-nitzschia cf. heimii (as determined by fluorescent in situ hybridisation assay; species specific probe heD2-2) with published descriptions* of species in the ‘Nitzschia seriata’ complex (Hasle 1965, 1975; Hasle & Syvertsen 1996).

Species	Apical axis (µm)	Transapical axis (µm)	Striae in 10 µm	Fibulae in 10 µm
P. heimii*	67–120	4–6	19–26	11–16
P. seriata f. seriata*	91–160	5.5–8	14–18	14–18
P. seriata f. obtuse*	61–100	4.5–5.3	15–20	15–20
P. subpacifica*	33–70	5–7	28–32	15–20
P. cf. heimii NZ (4 isolates)	46–95	3.7–4.1	32	18

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