Effects of temperature and irradiance on growth of strains belonging to seven Skeletonema species isolated from Dokai Bay, southern Japan

Figures & data

Fig. 1. Neighbour-joining (NJ) phylogram inferred from partial LSU rDNA sequences (795-bp long including alignment gaps) from 48 strains of 11 morphologically distinct taxa within Skeletonema with Cyclotella meneghiniana and Thalassiosira rotula as outgroups. NJ trees (Saitou & Nei, 1987) were constructed using the genetic distance estimated by the Kimura's two-parameter method (Kimura, 1980). Alignment gaps were excluded in the estimation of genetic distance, but the gaps were included in the pair-wise comparisons. Bootstrap values were calculated with 1000 replicates under the same settings as in the NJ analysis.

Table 1.  Isolated Skeletonema strains, strain ID, GenBank accession number, and date when each strain was isolated from Dokai Bay.

Species	Strain ID	GenBank accession	Isolation date
Skeletonema ardens	FDK003**	AB572611	04 Sep 2008
	FDK004	AB572612	04 Sep 2008
	FDK005	AB572613	04 Sep 2008
	FDK006	AB572614	04 Sep 2008
	FDK007	AB572615	04 Sep 2008
S. costatum s.s.	FDK009**	AB572617	02 Oct 2007
S. marinoi–dohrnii complex	FDK031**	AB572639	02 Feb 2009
	FDK032	AB572640	02 Feb 2009
	FDK033	AB572641	02 Feb 2009
	FDK035	AB572643	02 Feb 2009
	FDK039	AB572647	02 Feb 2009
S. japonicum	FDK154**	AB572762	09 Jul 2008
	FDK157	AB572765	09 Jul 2008
	FDK158	AB572766	09 Jul 2008
	FDK159	AB572767	09 Jul 2008
	FDK161	AB572769	09 Jul 2008
S. menzelii*	FDK221**	AB572829	10 Sep 2008
	DM08080630	AB573023	10 Sep 2008
	DM08080730	AB555561	10 Sep 2008
	FDK222	AB572830	10 Sep 2008
S. pseudocostatum*	FDK225**	AB572833	24 Aug 2007
S. tropicum	FDK199	AB572807	07 Oct 2008
	FDK202	AB572810	07 Oct 2008
	FDK204	AB572812	07 Oct 2008
	FDK205	AB572813	07 Oct 2008
	FDK207**	AB572815	07 Oct 2008
* Strains of S. menzelii and S. pseudocostatum were obtained from bottom sediment.
** Strains used for irradiance experiments.

Fig. 2. Specific growth rates for seven species of Skeletonema at various temperatures for (a) S. costatum s.s. (FDK009) and S. pseudocostatum (FDK225), (b) the S. marinoi–dohrnii complex, (c) S. japonicum, (d) S. tropicum, (e) S. menzelii and (f) S. ardens. Error bars indicate ± standard deviation (n = 3). Strain identities are indicated throughout (see Table 1).

Fig. 3. Box plots of specific growth rates for seven Skeletonema species at six temperatures: (a) 10, (b) 15, (c) 20, (d) 25, (e) 30 and (f) 35°C. Data for all strains of each species (see Table 1) were pooled and plotted at each temperature. Asterisks beside the temperature and lines under plots indicate significant differences of specific growth rate among the tested species (Kruskal–Wallis test, P < 0.01; Steel–Dwass test, P < 0.01). Skeletonema costatum s.s. and S. pseudocostatum were excluded from the statistical tests, since their specific growth rates were obtained from only one strain.

Fig. 4. Specific growth rates of strains of seven Skeletonema species as a function of irradiance. Curves were fit to a hyperbolic equation (see text for details). (a) S. ardens, (b) S. costatum s.s. (c) the S. marinoi–dohrnii complex, (d) S. japonicum, (e) S. menzelii, (f) S. pseudocostatum and (g) S. tropicum.

Table 2.  Strain ID, maximum specific growth rate (μ _max), half saturation constant (K _s), threshold value of irradiance (I ₀), saturation irradiance (S) and affinity index (α = μ _max/K _s) of seven Skeletonema species at 20°C.

Species	Strain ID	μ max	K S	I 0	S	α
		(d^−1)	(μmol m^−2 s^−1)	(μmol m^−2 s^−1)	(μmol m^−2 s^−1)	(μ max/K S)
S. ardens	FDK003	3.44	78	5.2	740	0.044
S. costatum s.s.	FDK009	1.50	30	5.9	237	0.050
S. marinoi–dohrnii complex	FDK031	1.65	31	5.4	257	0.053
S. japonicum	FDK154	1.88	56	7.6	491	0.034
S. menzelii*	FDK221	3.30	64	3.9	607	0.051
S. pseudocostatum*	FDK225	1.99	43	4.4	389	0.046
S. tropicum	FDK207	2.09	53	5.1	486	0.039
*Strains of S. menzelii and S. pseudocostatum were obtained from bottom sediment.

Table 3.  Literature values for maximum specific growth rate (μ _max), half saturation constant for irradiance (Ks), threshold value of irradiance (I ₀), saturation irradiance (S) and affinity index (α = μ_max /Ks) of some marine diatoms.

Species	μ max	Ks	I 0	S	α	Temperature	Reference
	(d^−1)	(μmol m^−2 s^−1)	(μmol m^−2 s^−1)	(μmol m^−2 s^−1)	(μ max /Ks)	(°C)
Skeletonema species	1.50–3.44	30–78	3.9–7.6	237–740	0.03–0.05	20	This study
S. costatum s.l.*	0.71	11	<0	112	0.06	15	Falkowski & Owens (1980)
S. costatum s.l.*	1.65	8	6.2	25	0.20	21	Chan (1978)
Chaetoceros sp.*	2.07	11	<0	107	0.20	21
Cylindrotheca fusiformis*	2.04	9	<0	90	0.23	21
Thalassiosira floridana*	2.35	23	<0	235	0.10	21
Thalassiosira eccentrica*	1.54	9	5.0	49	0.16	21
Thalassiosira curviseriata	1.34		~0	70		20	Popovich & Gayoso (1999)
Coscinodiscus wailesii	1.01	84	6.8	789	0.02	20	Nishikawa & Yamaguchi (2008)
Coscinodiscus granii	0.97	47	6.1	420	0.03	20
Eucampia zodiacus	3.08	63	7.9	563	0.05	20	Nishikawa & Yamaguchi (2006)
*Values are calculated from data of specific growth rates using Equation (2) and the method of Matsuda et al. (1999).

Table 4.  Temperature and specific growth rate ranges where Skeletonema species can maintain their population against flush-out of surface water of Dokai Bay (see text).

Species	Temperature (°C)	Specific growth rate (d^−1)
S. ardens	20–35	1.4–2.3
S. costatum s.s.	15–30	0.8–1.3
S. marinoi–dohrnii complex	10–30	1.0–1.6
S. japonicum	10–25	1.0–1.6
S. menzelii	15–35	1.2–2.0
S. pseudocostatum	15–30	1.2–1.9
S. tropicum	15–30	0.8–1.4

Saitou , N. and Nei , M. 1987 . The neighbor-joining method: a new method for reconstructing phylogenetic trees . Mol. Biol. Evol. , 4 : 406 – 425 .

 PubMed Web of Science ®Google Scholar

Kimura , M. 1980 . A simple method for estimating evolutionary rate of base substitutions through comparative studies of nucleotide sequences . J. Mol. Evol. , 16 : 111 – 120 .

 PubMed Web of Science ®Google Scholar

Falkowski , P.G. and Owens , T.G. 1980 . Light–shade adaptation, two strategies in marine phytoplankton . Plant Physiol. , 66 : 592 – 595 .

 PubMed Web of Science ®Google Scholar

Chan , A.T. 1978 . Comparative physiological study of marine diatoms and dinoflagellates in relation to irradiance and cell size. I. Growth under continuous light . J. Phycol. , 14 : 396 – 402 .

 Web of Science ®Google Scholar

Popovich , C.A. and Gayoso , A.M. 1999 . Effect of irradiance and temperature on the growth rate of Thalassiosira curviseriata Takano (Bacillariophyceae), a bloom diatom in Bahîa Blanca estuary (Argentina) . J. Plankt. Res. , 21 : 1101 – 1110 .

 Google Scholar

Nishikawa , T. and Yamaguchi , M. 2008 . Effect of temperature on light-limited growth of the harmful diatom Coscinodiscus wailesii, a causative organism in the bleaching of aquacultured Porphyra thalli . Harmful Algae , 7 : 561 – 566 .

 Google Scholar

Nishikawa , T. and Yamaguchi , M. 2006 . Effect of temperature on light-limited growth of the harmful diatom Eucampia zodiacus Ehrenberg, a causative organism in the discoloration of Porphyra thalli . Harmful Algae , 5 : 141 – 147 .

 Google Scholar

Matsuda , A. , Nishijima , T. and Fukami , K. 1999 . Effects of nitrogenous and phosphorus nutrients on the growth of toxic dinoflagellate Alexandrium catenella . Nippon Suisan Gakk. , 65 : 847 – 855 .

 Google Scholar