GeoJournal 17.1 8 5 - 8 9 © 1988 by Kluwer Academic Publishers

85

Biogeographical Afl'mities of Marine Algae in the Saronikos Gulf, Athens, Greece Diapoulis, Aristidis, Dr.; Koussouris, Theodoros, Dr., National Centre for Marine Research, 16604 Agios Kosmas, Hellenikon, Athens, Greece Savas, Haritonidis, Prof., Botanical Institute, University of Thessaloniki, 54006 Thessaloniki, Greece

ABSTRACT: Hard substrate photophilius marine algae species of the Saronikos Gulf amount to 197. Of them, 42 were Atlantic subtropical, 36 Atlantic tropical, and just 19 Atlantic boreal and 11 Boreal. The R/P ratio was 3.22. This shows the Atlantic subtropical character of the marine flora.

Introduction

The biogeographic distribution and extension of marine algae is not fully studied on a worldwide scale and, therefore, this subject is of great interest.

The present paper deals with the biogeographic relationships of photophiles marine algae on hard substrate in Saronikos Gulf (Greece).

The classification and biology of marine algae in Saronikos Gulf, was studied for the first time by Schmitz (1878), while later De Tone (1901) presented a catalogue of the algae species of that area. A more systematic work was made by Politis (1934), and, more recently, Diapoulis (1980) and Diapoulis and Verlaque (1981), identified 17 species recorded for the first time for the Greek waters in Saronikos Gulf.

For the purpose of the present study, an experi- mental survey was carried out in order to select a representative grid of stations in the Saronikos Gulf.

Material and Methods

Adequate bottom samples were taken on hard substrate, at depths ranging between 0 and 5 m through- out the year.

The total number of species (Q), whole coverage area (E Ri) of different floristic elements and qualitative dominance of each group (DO) were determined for each station (e.g., Boudouresque & Cinelli 1971, 1976; Belsher 1977).

Results and Discussion

According to our findings, 197 species were determined, belonging to the following four systematic groups: 119 species of Rhodophyceae, 7 species of Chlorophyceae, 34 species of Bryopsidophyceae and 37 species of Phaeophyceae. The forementioned floristic elements in Saronikos Gulf belong to the following biogeographic groups (for a review see Ardre 1970; Boergesen 1915-1920; Boudouresque 1970; Boudoures- que and Denizot 1975; Ercegovic 1957; Feldmann- Mazoyer 1940; FeIdmann and Hamel 1936; Giaccone and Longo 1976; Hoek and Donze 1967; Verlaque 1977): Mediterranean: It comprises endemic species as well as species originating from the centre of the Mediterranean sea and recently colonized spezies from the Atlantic coasts and the Red-Sea. Pantropic: It comprises warm sea species. Atlantic tropical: They are found from the French Atlantic coast to the equatorial African coast. Atlantic subtropical: They are intermediate between the Atlantic tropical and the Atlantic boreal groups. They are found on the Atlantic coasts of Morocco, Portugal, NW Spain, Azores as well as in the Mediterranean Sea. Atlantic boreal: They are spread from Ireland to Morocco. Boreal: Usually found from Norway to the NW coasts of Spain. Few species are observed in the Mediterranean. Cosmopolitan." They are found in different geographic latitudes, with different temperatures.

86 GeoJoumal 17.1/1988

Tab 1 The number of species, the coverage and the qualitative and quantitative dominance in the stations during autumn

Tab 2 The number of species, the coverage and the qualitative and quantitative dominance in the stations during winter

GeoJournal 17.1/1988 87

3 5

3 6 ~ , ~715%

Tab 3 The aumber of species, the coverage and the qualitative and quantitative dominance in the stations during spring

Tab 4 The mlmber of species, the coverage and the qualitative and quantitative dominance in the stations during summer

i:iil;i ~i~ii: ~ ~" i;ii~ii ,~ ~ .......

S ta f i~S : Summer D O . . Q

eBl~°g;°ngtr't Q: : : I . 2 :3 4 5 6 7

Ri . Summer DRi

7 1 2 3 4 5 6 7

12 9 0 9 5 9 o 9 6 Mediterranean ] 13.5% I0.5~/o 13 % 7.7% 11 Yo 11.1% 9.7%

Cosmopolitatl = t2 13 10 11 13 12 1S 266"6~ 67,3o 13.9o 2 5 o 35,4v 35.6o 34.51 ° ' . . . . " ": . . . . . . . . . . . . " i 13.5% ~5. I% i4,5% 17 % 15.8% 14.8%, 19.3% 6.5% 29,7Yo 6.5% 15 % 16,9% 15,1% I8. go

16 :15 11 1_2 16 15 8 24,8 51 63.7 26.,7 27.9 32.8 20.7 a ~o o o o 0 o o o o' o o ,o - 18 Y~ 17. % 16 % 18.5Yo 19.5Yo 18.5Yo 12.9Yo 9.8Yo 22,6Yo 30 Yo 16 Yo I3.3% 13,9Yo 10.8Yo

~; Q ' ' 8 i 6 2 E R i 2 5 1 . 7 2 2 209 .3236 .1 : 190.7

I00 % 100 % 100 % 100.1% 99.9% 99.9 S~ D Q t ,% 1 ~ % £DRi 104) % 99.9% 99.9% I00.1% 99.8% 100 % 99.9% , , , :

8 8 GeoJournal 1 7 . 1 / 1 9 8 8

, . • . : : . . - : ( , . . . . . . . : . . : • . • . . :~ :.~'

~::~::: : ::!:::~i:: : ~ / : ~ : ,;i! .... • ~!:i::' as"

:.!-.,'-'.:i:~ .:" ' ;7.1- so'

"..: :.. ' ": +:::" 4o'

Fig 1 Map of Saronikos Gulf showing the sampling stations

Unidentified species as well as species of unknown geographical distribution were excluded from that analysis.

Qualitative Changes

Some general remarks can be drawn from the qualitative dominance of different floristic elements throughout the year: The Atlantic sub-tropical element dominates at stations 1, 2 and 4 during all seasons, at station 3 in summer and autumn, and at station 6 during all seasons but spring (Tab 1, 2, 3 and 4). The Atlantic tropical element dominates at station 3 during winter and spring, at station 5 during winter, spring and

summer, and at station 6 in spring. Generally, according to our data most of the stations in Saronikos Gulf belong to the Atlantic tropical and subtropical floristic element, while the contribution of the Boreal and the Atlantic boreal floristic element is not considerable. The former participate with 11 species, or about 5.6% of the total number of species found, and the latter with 19 spezies, or about 9.6% of the total number of species found.

Quantitative Estimations

The analysis of the quantitative dominance shows that the presence of at least one species could affect considerably the results (Tab 5, 6 and 7). For instance, the seasonal changes of the Red-Alga Corallina granifera affect the quantitative dominance of the Mediterranean floristic element at station 4 (Tab 5). The same is true for station 5, where quantitative seasonal changes of Padina pavonica affects the dominance of the Pantropical element (Tab 6). The seasonal quantitative changes of the Cosmopolitan Sphacelaria cirrosa effects significantly the dominance of this element at station 7 (Tab 7).

Generally our results indicate that marine algae in the Saronikos Gulf belong mainly to the Atlantic sub- tropical group. The contribution of the Atlantic tropical floristic element is also quite important, while, on the contrary, the contribution of the Boreal and Atlantic boreal floristic element is very low. Thirty one species of the Atlantic subtropical element were found at all stations, the main species being: Dictyota dichotoma, D. linearis, Dilophus spiralis, Stypocaulon scoparium,

Tab 5 Seasonal variation of the Mediter- ranean element (due exclusively to Corallina granifera)

Tab 6 Seasonal variation of the Pantropic element (due exclusively to Padina pavonica)

Tab 7 Seasonal variations of the Cosmo- politan element (due exclusively to Sphacelaria cirrosa)

GeoJournal 17.1/1988 89

Chondria tenuissima, Lithothamnium lenormandii, Polysiphonia furcellata, Laurencia pinnatifida, Codium bursa, and Cladophora echinus. T w e n t y six species o f the A t l a n t i c t rop ica l e l e m e n t w e r e iden t i f i ed at all s ta t ions , t he m a i n species be ing: Valonia utricularis, Caulerpa prolifera. Udotea petiolata, Cladophora prolifera, Dasycladus vermicularis, and Lophosiphonia subadunca.

B e y o n d the qua l i t a t i ve and quan t i t a t i ve cha rac t e r o f f lor is t ic e l e m e n t s , t he R / P ra t io has b e e n e s t ima ted . I t

has b e e n d e m o n s t r a t e d tha t t he ra t io R / P m a y a d e q u a t - ely desc r ibe the geog raph i ca l n a t u r e of t he m a r i n e f lora

in a g iven hab i t a t ( F e l d m a n n 1937). T h e R / P ra t io ranges

b e t w e e n 1 - 5 , and acco rd ing to the va lue of t he ra t io ,

m a r i n e f lora is c lassif ied as arct ic , bo rea l , i n t e r m e d i a t e , sub t rop ica l and t ropica l .

D i f f e r e n t va lues of t h e R / P ra t io h a v e b e e n e s t i m a t e d in va r ious a reas o f t he E M e d i t e r a n e a n sea. F o r

ins tance , 4 in the A e g e a n sea ( G i a c c o n e 1968), 2 in Tu rk i sh coasts ( G t i v e n and Ozt ig 1971), 2.5 in G r e e k

coasts ( G e r l o f f and Ge i s s l e r 1973), 2.8 in W e s t e r n G r e e k coasts (Haz i ton id i s and T s e k o d 1976), 3.69 in R h o d o s

is land (D iapou l i s et al. 1986). In t he p r e s e n t s tudy the .R/P ra t io was f o u n d to be 3.22 which shows the A t l a n t i c

sub t rop ica l c h a r a c t e r of m a r i n e f lo ra in t he Sa ron ikos Gul f .

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