HELGOLANDER MEERESUNTERSUCHUNGEN Helgol~inder Meeresunters. 41,323-327 (1987)
Lethal e x p o s u r e times and p r e c o n d i t i o n i n g to u p p e r
temperature limits of s o m e temperate N o r t h Atlantic
red a l g a e
C. Y a r i s h 1, H. K i r k m a n 2 & K. Lfining 3
1 Department of Ecology and Evolutionary Biology, University of Connecticub Scofield- town Road, Stamford, CT 06903, USA
z CSIRO, Marine Laboratories; P.O. Box 20, North Beach, W.A. 6020, Australia 3 Biologische Anstalt Helgoland (Zentrale); Notkestr. 31, D-2000 Hamburg 52, FRG
A B S T R A C T : Using the red alga Polyneura hifliae as an example, the m i n i m u m time taken for lethal temperature exposure, with no regeneration capacity left, was 2 Weeks. Employing this exposure time, the upper temperature limits of the following 13 red algal species belonging to four biogeo- graphical distribution groups were determined: Callophylh's laciniata, Polyneura hilliae, Hypo-
glossum hypoglossoides, Halurus equisetifolius, iomentaria arficulata, Cryptopleura rarnosa, Calli- blepharis ciliata (warm-temperate Mediterranean-Atlantic group); Calh'thamnion tetragonum, Lomentaria orcadensis (amphiatlantic-temperate group); GAnnellia americana, Lomentaria bailey- ana, Agardhiefla subulata (northeast American tropical-temperate group), Solieria tenera (amphiat- lantic tropical-temperate group). Pre-incubation temperatures of 10 and 20 ~ for one month (or 15 and 25 ~ for the two last-mentioned distribution groups) did not measurably affect the critical survival temperature.
I N T R O D U C T I O N
I n v e s t i g a t o r s w h o h a v e a t t e m p t e d to correlate the t e m p e r a t u r e r e q u i r e m e n t s for survival of b e n t h i c m a r i n e a l g a e w i t h their p h y t o g e o g r a p h i c d i s t r i b u t i o n h a v e e m p l o y e d differing e x p o s u r e t i m e s to limiting t e m p e r a t u r e s . To give a few e x a m p l e s , Montfort et al. {1957} u s e d 3 h, Biebl {1958, 1962} 12 h, Ltining (1984} 1 w e e k , Bolton {1983) 3 w e e k s , M c L a c h l a n & Bird (1984), Yarish et al. (1984, 1986) 5 w e e k s , a n d C a m b r i d g e et al. {1984} 2 months. T h e first o b j e c t i v e of the p r e s e n t p a p e r w a s to p r o v i d e a c o m p l e t e t i m e series at l e a s t for one a l g a in o r d e r to o b t a i n s o m e i d e a a b o u t the m i n i m u m e x p o s u r e t i m e after w h i c h the u p p e r l e t h a l t e m p e r a t u r e r e m a i n s c o n s t a n t for the n e x t few months.
T h e s e c o n d o b j e c t i v e c o n c e r n e d a n o t h e r u n c e r t a i n t y of t h e e x p e r i m e n t a t o r , n a m e l y the selection of t h e t e m p e r a t u r e at w h i c h a l g a e s h o u l d b e k e p t a n d p r o p a g a t e d prior to t r e a t m e n t at the e x p e r i m e n t a l t e m p e r a t u r e s . Does p r e - i n c u b a t i o n at t e m p e r a t u r e s differ- i n g b y as m u c h as e.g. 10 ~ c h a n g e the u p p e r l e t h a l t e m p e r a t u r e ? S u c h c a s e s of "non- g e n e t i c r e s i s t a n c e a d a p t a t i o n " (Precht et al., 1955, 1973; Kinne, 1970} or "plastic resist- ance", in the t e r m i n o l o g y of Levitt (1980), h a v e b e e n i n v e s t i g a t e d m o r e in m a r i n e a n i m a l s (e.g. Newell, 1976}. T h e few e x p e r i m e n t s r e p o r t e d on m a r i n e a l g a e (for r e v i e w of the o l d e r l i t e r a t u r e s e e G e s s n e r , 1970} s t r e s s e d the stability of t h e u p p e r l e t h a l survival limit
a n d t h e i n a b i l i t y of t h e e x p e r i m e n t a t o r t o s h i f t t h e s e l i m i t s b y c h o o s i n g d i f f e r i n g p r e - i n c u b a t i o n t e m p e r a t u r e s .
T h e l a s t o b j e c t i v e w a s to d e t e r m i r i e p r e c i s e l y , i n t e m p e r a t u r e s t e p s b y 1 ~ t h e u p p e r s u r v i v a l l i m i t s of 13 s p e c i e s of r e d a l g a e . F o r t h e s e t h e p h y t o g e o g r a p h i c b o u n d a r i e s , t e m p e r a t u r e d e m a n d s for g r o w t h a n d r e p r o d u c t i o n , a n d t h e s u r v i v a l l i m i t s i n t e m p e r a - t u r e s t e p s b y 5 ~ h a v e b e e n p r e s e n t e d e a r h e r ( Y a r i s h e t al., 1984, 1986).
M A T E R I A L A N D M E T H O D S
T h e i n o c u l a for e x p e r i m e n t a t i o n c o n s i s t e d of c l o n e d c u l t u r e s (cf. Y a r i s h e t el., 1984, 1986 for c o l l e c t i o n d a t a ) a n d w e r e p r o p a g a t e d a t 15 ~ i n v o n S t o s c h ' s e n r i c h e d s e a w a t e r m e d i u m (Ott, 1966) h a v i n g a s a l i n i t y of 33 %o. S t a n d a r d h g h t c o n d i t i o n s : c o o l f l u o r e s c e n t h g h t , p h o t o n f l u e n c e r a t e of 3 0 ~ m o l m - 2 s -1, 16 h h g h t p e r d a y . T e s t s o n t e m p e r a t u r e s u r v i v a l w e r e p e r f o r m e d , a s d e s c r i b e d i n d e t a i l b y L f i n i n g e t el. (1987}. I n s h o r t , i s o l a t e s {0.2-0.3 g f r e s h w e i g h t } w e r e i n c u b a t e d i n P l e x i g l a s c y l i n d r i c a l j a r s {140 m l of c u l t u r e m e d i u m ; V o n S t o s c h ' s E n r i c h e d S e a w a t e r a t h a l f s t r e n g t h ; cf. G u i r y & C u n n i n g h a m , 1984) c o n t a i n e d i n i l l u m i n a t e d b a t h - c r y o s t a t u n i t s . T h e c u l t u r e m e d i u m w a s r e p l a c e d a u t o m a t i c a l l y o n c e a d a y . A f t e r a s t a n d a r d t r e a t m e n t of 2 w e e k s t h e p l a n t s w e r e p o s t - i n c u b a t e d u n d e r g o o d g r o w i n g c o n d i t i o n s (15 ~ for 4 w e e k s t o c h e c k for s u r v i v a l a n d for r e g e n e r a t e d t h a U i f r o m a f e w h v i n g c e l l s i n t h e o t h e r w i s e b l e a c h e d t i s s u e . I n c a s e s w h e r e t h e r e h a d b e e n a n y d o u b t a b o u t t h e v i a b i l i t y of t h e t r e a t e d m a t e r i a l , t h e p o s t - i n c u b a t i o n w a s p r o l o n g e d f o r a n o t h e r 4 w e e k s .
R E S U L T S A N D D I S C U S S I O N
T h e s u r v i v a l r e s p o n s e s of t h e g a m e t o p h y t e s of Polyneura hilliae are g i v e n for a p e r i o d of u p t o 5 6 d a y s ( T a b l e 1) a t t e m p e r a t u r e s of 20, 2 4 - 3 0 ~ A f t e r a s i x - h o u r
Table 1. Survival r e s p o n s e s of Polyneura hilliae g a m e t o p h y t e s over e i g h t weeks, xxx p l a n t s alive (with sight observation a n d confirmation after 4 w e e k s post-incubation at 15 ~ reg. r e g e n e r a t i o n of
purportedly " d e a d " tissue after four w e e k s at 15 ~ - - - plants d e a d
T e m p e r a t u r e over eight weeks
(~
Time (d) 20 24 25 26 27 28 29 30
1/4 xxx xxx xxx xxx reg. reg.
1 xxx xxx xxx xxx reg. - - -
2 xxx xxx xxx reg. - . . .
3 xxx xxx xxx reg. - . . .
5 xxx xxx xxx reg. - . . . 7 xxx xxx reg. - . . . 10 xxx xxx reg. - . . . 14 xxx xxx . . . . 21 xxx x:c_x . . . . 28 xxx xxx . . . . 37 xxx xxx . . . . 42 xxx xxx . . . . 56 xxx xxx . . . .
- - - - ~
~
~
~
~176
~176
--~
4 - - - -
.--~
L e t h a l e x p o s u r e t i m e s a n d t e m p e r a t u r e l i m i t s 325
Table 2. Upper survival temperature and geographical boundaries of selected temperate North Atlantic red algae. Exposure time to experimental temperatures was 2 weeks. Temperature values in brackets following the geographical boundaries indicate the mean August isotherms (according to Sverdrup et al., 1942} of the surface seawater at the corresponding locations. Nomenclature according to South & Tittley (1986}. trestricted to shallow embayments where summer temperatures exceed 17 ~ thereby permitting growth and reproduction Pre-incubation temperatures: Distribution groups 1 and 2: continuously at 15 ~ ( "); transferred for one month to 10 or 15 ~ (" "; identical upper survival temperature). Distribution groups 3 and 4: continuously at 20 ~ (*" *), or transferred for one
month to 20 or 25 ~ {'" "" ; identical upper survival temperature)
Species Northern Southern Upper survival
boundary boundary temperature (~
(1) W a r m - t e m p e r a t e M e d i t e r r a n e a n - A t l a n t i c g r o u p
Europe Europe/Africa
Callophyllis laciniata (Huds.) Kfitz.
Polyneura hilliae (Grev.) Kylin Hypoglossum hypoglossoides (Stackh.) F. Coll. et Hervey Halurus equisetifolius (Lightf.) K/itz. tomentaria articulata (Huds.) Lyngbye Cryptopleura ramosa (Huds.) Kylin ex Newton CaUiblepharis ciliata (Huds.) K/itz.
Norway (11) Morocco (2 i) 24"
Ireland (14) Portugal (19) 2 4 ' " Shetland Is. (12) Cameroun (27) 25""
Ireland (13) Canaries (22) 26"
Norway (11) Madeira Is. (21) 27" '
Faer6es (11) Madeira Is. (21) 27 ' ~
Ireland (14) Portugal (19) 2 7 ' "
Europe or Europe/Africa or N. America N. America
Madeira Is. (21) 25" ~
Virginia {25)
Portugal (20) 27 ~ ' (2) A m p h i a t l a n t i c - t e m p e r a t e g r o u p
Callithamnion tetragonum Iceland (10) (With,) S. F. Gray Norway (10)
Newfdl. (12) Lomentaria orcadensis Iceland (10) [Harvey) F. Colhns ex W. Tayl. Norway (10)
Nova Scotia (15)
(3) N o r t h e a s t A m e r i c a n t r o p i c a l - t e m p e r a t e
N. Carolina (25)
g r o u p Griunetlia americana
(C. Ag.) Harvey Lomentaria bafleyana (Harvey) Farlow Agardhiella subulata (C. Ag.) Kraft et Wynne
Massachusetts (i7) Tropical margins 31""" (Florida)
s. Gulf of (15) Tropical margins 33"" ' St. Lawrence t (s. Florida)
s. Gulf of (15) Tropics 33 . . . . St. Lawrence 1
(4) A m p h i a t l a n t i c t r o p i c a l - t e m p e r a t e g r o u p Solieria filiformis (= tenera) N. Carolina (25) Tropics (K~itz.) Gabrielson
t r e a t m e n t in t h e w a t e r b a t h s , t e m p e r a t u r e s e x c e e d i n g 28 ~ w e r e lethal. P l a n t s i n c u b a t e d at 27-28 ~ a p p e a r e d d e a d ; h o w e v e r , . t h e y b e g a n to r e g e n e r a t e after b e i n g r e i n c u b a t e d at 15 ~ After 1 - d a y t r e a t m e n t , t h e r e g e n e r a t i o n c a p a c i t y w a s f u r t h e r d i m i n i s h e d to 27 ~ after t r e a t m e n t s of 2 - 5 d a y s d u r a t i o n to 26 ~ a n d after t r e a t m e n t d u r a t i o n of 7 - 1 0 d a y s to 25 ~ T h e u p p e r survival limit at 24 ~ w a s c o n s t a n t from a n e x p o s u r e t i m e of 14 d a y s o n w a r d .
It is i n t e r e s t i n g to n o t e t h a t a t w o - w e e k i n c u b a t i o n p e r i o d w a s sufficient for d e t e r - m i n i n g the isolates' u p p e r survival limits a n d t h a t t h e d i f f e r e n c e b e t w e e n s u r v i v a l a n d d e a t h of the c o m p l e t e thallus m a y b e a m a t t e r of 1 ~ (Table 1). T h e p r e c i s i o n of t h e t e c h n i q u e e m p l o y e d m u s t b e e m p h a s i z e d as o n e - d e g r e e i n t e r v a l s w e r e u s e d for e a c h t a x o n in contrast to o t h e r e x p e r i m e n t s , w h i c h a r e often set in 5 ~ i n t e r v a l s . T h e i m p o r t a n c e of p o s t - i n c u b a t i o n i n s t e a d of v i s u a l i n s p e c t i o n right after t h e t r e a t m e n t c a n n o t b e o v e r - e m p h a s i z e d . P o s t - i n c u b a t i o n w a s p a r t i c u l a r l y n e e d e d for
Hypoglossum
hypoglossoides, Lomentaria articulata, Callithamnion tetragonum,
a n dPolyneura hilliae,
as e a c h w a s a b l e to r e g e n e r a t e entire thalli from o n l y a few cells. It is s u g g e s t e d for f u t u r e r e s e a r c h in the d e t e r m i n a t i o n of the u p p e r l e t h a l limits of a l g a l t a x a t h a t a 5 ~ i n t e r v a l s h o u l d b e e s t a b h s h e d e n c o m p a s s i n g t h e l e t h a l t e m p e r a t u r e . After t h e i n t e r v a l h a s b e e n f o u n d out, t h e n t h e p r e c i s e l e t h a l limit s h o u l d b e d e t e r m i n e d b y i n c u b a t i o n at 1 ~ i n t e r v a l s for at l e a s t two w e e k s w i t h f r e q u e n t c h a n g e of.culture m e d i u m .T a b l e 2 exhibits the survival r e s p o n s e s of all i n v e s t i g a t e d a l g a l s p e c i e s . T h e u p p e r survival hmits of t h e w a r m - t e m p e r a t e s p e c i e s (groups 1 a n d 2 in T a b l e 2) r a n g e at 24-27 ~ w h e r e a s s p e c i e s with t r o p i c a l affinities (groups 3 a n d 4) a r e c l e a r l y differenti- a t e d b y v a l u e s r a n g i n g at 31-33 ~
N i n e out of the 13 s p e c i e s i n v e s t i g a t e d w e r e t e s t e d after p r e - i n c u b a t i o n for o n e m o n t h at t e m p e r a t u r e s differing b y 10 ~ (Table 2). I d e n t i c a l v a l u e s for t h e u p p e r s u r v i v a l t e m p e r a t u r e w e r e o b t a i n e d in all cases. A p p a r e n t l y , the isolates h a d n o a b i l i t y to shift t h e i r u p p e r l e t h a l t e m p e r a t u r e . This is in a c c o r d a n c e w i t h results r e p o r t e d for m o s t of t h e s m a l l e r m a r i n e a l g a l s p e c i e s from H e l g o l a n d , w h e r e a s s e a s o n a l shifts of u p p e r t e m p e r a - ture t o l e r a n c e w e r e r e a d i l y d e t e c t e d in l a r g e r a l g a e , e.g.
Laminaria
spp. a n dDesmarestia
aculeata
(Liining, 1984 a n d o l d e r h t e r a t u r e cited herein). D u r i n g t h e cold s e a s o n , t h e s e a l g a e form new, h e a t - s e n s i t i v e tissue, w h i c h s u b s e q u e n t l y " h a r d e n s " a n d e x h i b i t s a 2 - 5 ~ h i g h e r t e m p e r a t u r e t o l e r a n c e in s u m m e r . It m a y w e l l b e p o s s i b l e t h a t in s m a l l e r a l g a e the y o u n g e s t cells are m o r e h e a t - s e n s i t i v e a n d t h a t this effect is e a s i l y o v e r l o o k e d for t e c h n i c a l reasons, b e c a u s e in l a r g e r a l g a e o n e c a n e a s i l y t r e a t old a n d y o u n g t i s s u e s e p a r a t e l y . T h e u p p e r survival t e m p e r a t u r e s l i s t e d in T a b l e 2 c a n n o t b e d i r e c t l y r e l a t e d to t h e positions of t h e s p e c i e s ' s o u t h e r n limits, as o t h e r factors (e.g. t e m p e r a t u r e s l i m i t i n g g r o w t h a n d / o r r e p r o d u c t i o n ) m a y b e i m p o r t a n t . M o r e o v e r , e x t r e m e t e m p e r a t u r e . v a l u e s a r e m o r e i m p o r t a n t t h a n a v e r a g e v a l u e s (see Yarish et al., 1984, 1986).L e t h a l e x p o s u r e t i m e s a n d t e m p e r a t u r e l i m i t s 327
L I T E R A T U R E CITED
Biebl, R., 1958. T e m p e r a t u r - u n d osmotische Resistenz von M e e r e s a l g e n der b r e t o n i s c h e n Kfiste. - Protoplasma 50, 217-242.
Biebl, R., 1962. T e m p e r a t u r r e s i s t e n z tropischer Meeresalgen. - Botanica mar. 4, 241-254.
Bolton, J. J., 1983. Ecoclinal variation in Ectocarpus siliculosus (Phaeophyceae) w i t h respect to t e m p e r a t u r e growth optima a n d survival limits. - Mar. Biol. 73, 131-138.
Cambridge, M., Breeman, A. M., Oosterwyk, R. & Hoek, C. v a n den, 1984. T e m p e r a t u r e r e s p o n s e s of some N. Atlantic Cladophora species (Chlorophyceae) in relation to their g e o g r a p h i c distribu- tion. - HelgolSnder Meeresunters. 38, 349-363.
Gessner, F., 1970. Temperature. Plants. In: M a r i n e ecology. Ed. by O. Kinne. Wiley-Interscience, London, I (I), 363-406.
Guiry, M. D. & C u n n i n g h a m , E. M., 1984. Photoperiodic a n d t e m p e r a t u r e r e s p o n s e s in the reproduc- tion of n o r t h - e a s t e r n Atlantic Gigartina acicularis (Rhodophyta: Gigartinales). - Phycologia 23, 357-367.
Kinne, O., 1970. T e m p e r a t u r e : Animals: Invertebrates. In: Marine ecology. Ed. b y O. Kinne. Wiley- Interscience, London, 1 (1), 407-514.
Levitt, J., 1980. Responses of plants to e n v i r o n m e n t a l stress. Acad. Press, N e w York, I, 1--497. Lfining, K., 1984. T e m p e r a t u r e resistance a n d b i o g e o g r a p h y of seaweeds: the m a r i n e algal flora of
Helgoland, North Sea, as a n example. - HelgolSnder Meeresunters. 38, 305-317.
Liining, K., Guiry, M. D. & Masuda, M., 1987. U p p e r t e m p e r a t u r e tolerance of North Atlantic a n d North Pacific g e o g r a p h i c isolates of the r e d algae Chondrus. - HelgolSnder M e e r e s u n t e r s . 41, 297-306.
McLachlan, J. & Bird, C. J., 1984. G e o g r a p h i c a l a n d e x p e r i m e n t a l "assessment of the distribution of species of Gracflaria in relation to temperature. - Helgol~inder Meeresunters. 38, 319-334. Montfort, C , Pied, A. & Pied, I., 1957. A b s t u f u n g e n der funktionellen WSrmeresistenz bei
M e e r e s a l g e n in i h r e n B e z i e h u n g e n zu U m w e l t u n d Erbgut. - Biol. Zbl. 76, 257-289.
Newell, R. C. (Ed.), 1976. A d a p t a t i o n to the environment: essays on the physiology of m a r i n e animals. Butterworths, London, 539 pp.
Ott, F. D., 1966. A selected listing of axenic algal cultures. - Coll. Repr. Woods Hole Oceanogr. Instn 72, 1-20.
Precht, I--I., Christophersen, J. & Hensel, H., 1955. T e m p e r a t u r u n d Leben. Springer, Berlin, 514 pp. Precht, H., Christophersen, J., Hensel, H. & Larcher, W. (Eds), 1973. T e m p e r a t u r e a n d life. Springer,
Berlin, 779 pp.
South, G. R. & Tittley, I., 1986. A checklist a n d distributional index of the b e n t h i c m a r i n e algae of the North Atlantic Ocean. H u n t s m a n M a r i n e Laboratory, St. Andrews, 76 pp.
Sverdrup, H. U., Johnson, M. W. & Fleming, R. H., 1942. The oceans. Prentice Hall, E n g l e w o o d Cliffs, N. J., 1060 pp.
Yarish, C., Breeman, A. M. & Hoek, C. v a n den, 1984. Temperature, light a n d p h o t o p e r i o d r e s p o n s e s of some Northeast A m e r i c a n a n d West E u r o p e a n e n d e m i c rhodophytes in relation to t h e i r geographical distribution. - HelgolSnder Meeresunters. 38, 273-304.
