• No results found

Importance and abundance of the recently established speciesCoscinodiscus wailesii Gran & Angst in the German Bight

N/A
N/A
Protected

Academic year: 2020

Share "Importance and abundance of the recently established speciesCoscinodiscus wailesii Gran & Angst in the German Bight"

Copied!
20
0
0

Loading.... (view fulltext now)

Full text

(1)

HELGOLANDER MEERESUNTERSUCHUNGEN Helgolfinder Meeresunters. 49, 355-374 (1995)

Importance and abundance of the recently established

species

C o s c i n o d i s c u s w a i l e s i i

Gran & Angst in the

German Bight

H.-J. R i c k I & C . - D .

D i i r s e l e n 2 .

~ Institut ffir Chemie und Biologie des Meeres (ICBM), Carl-von-Ossietzky-Universitfit Oldenburg; Carl-von-Ossietzky-StraBe 9-1 i, D-26111 Oldenburg, Germany 2 Institut ffJr Biologie L Lehr- und Forschungsgebiet Okologie des Bodens, Rheinisch Westf~lische Technische Hochschule Aachen; Worringerweg, D-52056 Aachen, Germany

ABSTRACT: Grids of 17 to 50 stations in the G e r m a n Bight were sampled 18 times within the framework of the multidisciplinary programmes ZISCH and PRISMA in winter and spring of 1988/89 and from April 1991-April I992. The frequent a b u n d a n c e of Coscinodiscus wafles/i Gran & Angst, a recently established large diatom, was noteworthy, as it dominated the phytoplankton biomass over long periods (e.g. 12/88-3/89 and 8/91-11/91). The bulk of the phytoplankton carbon during these periods (up to 90 %) could be attributed to this species. Blooms of Coscinodiscus wailesii producing up to 1400 ag carbon 1 -t , w e r e recorded in early spring of 1989 and autumn of 1991. The potential c o n s e q u e n c e s for the whole ecosystem refer to the h u g e size of this organism, which may cause r e d u c e d exploitation of its primary production by native consumers. Furthermore, sedimentation and remineralisation processes may be affected. For C wailesii, a doubling of biomass in 70 h could be estimated on the basis of data from four successive surveys in 1991. Results from laboratory cultures u n d e r comparable conditions confirm this rate. In the survey area, no increase in biomass was recorded for the related Coscinodiscus granii Gough, although there was sufficient silicate supply for growth. Field data s h o w e d 8-10 times lower copper and 10-20 times lower cadmium and zinc accumulation in C. wailesii, compared to concentrations found in native phytoplankton species. S u b s e q u e n t laboratory tests s u g g e s t e d that one reason for the remarkable success of C. wailesii, mainly in inshore regions, may be derived from its tolerance of higher doses of heavy metals due to very low sorption.

I N T R O D U C T I O N

T h e s p r e a d i n g of p l a n k t o n s p e c i e s i n d i f f e r e n t p a r t s of t h e w o r l d o c e a n s is n o t a n e w p h e n o m e n o n . S p r e a d i n g m a y b e c a u s e d b y o c e a n c u r r e n t s t r a n s p o r t i n g d r i f t i n g o r g a - n i s m s , b y m e r c h a n t s h i p s t r a n s f e r r i n g b a l l a s t w a t e r ( G e r l a c h , 1992) or b y s t o c k i n g t h e s e a s w i t h l i v i n g o r g a n i s m s n a t i v e to o t h e r c o u n t r i e s ( R i n c e & P l a u m i e r , 1986).

F o r t h e N o r t h S e a , a n u m b e r of e x a m p l e s of n e w a r r i v a l s i n t h e p h y t o p l a n k t o n a r e k n o w n , e.g. Odontella (Biddulphia) sinensis G r e v . ( O s t e n f e l d , 1908, 1909); Thalassiosira punctigera C a s t r . (Kat, 1982); Thalassiosira h e n d e y i H a s l e & F r y x e l l (Rick, 1990)

Corethron criophflum, Stephanopyxis palmeriana ( D r e b e s , 1991); Gyrodinium aureolum

* Present address as 1

(2)

356 H.-J. Rick & C.-D. D i i r s e l e n

H u l b u r t (Tangen, 1977); Pleurosigma planktonicum S i m o n s e n (Boalch & H a r b o u r , 1977a); Coscinodiscus wailesii G r a n & A n g s t (Boalch & H a r b o u r , 1977b; R o b i n s o n et al., 1980; Rince & Plaumier, 1986). In most c a s e s t h e s e n e w arrivals are not s t o c k - f o r m i n g in their n e w d i s t r i b u t i o n areas, w i t h the e x c e p t i o n of t h e m e n t i o n e d d i n o f l a g e l l a t e , a n d the l a r g e centric d i a t o m s Odontella sinensis a n d Coscinodiscus wailesii. T h e y m a y h a v e a s t r o n g i m p a c t on the structure of the p e l a g i c e c o s y s t e m b y p a r t l y r e p l a c i n g n a t i v e p o p u l a t i o n s d u r i n g c e r t a i n seasons.

Coscinodiscus wailesii shows a w o r l d w i d e distribution. A r e v i e w is g i v e n in Rince & P l a u m i e r (1986). It is found b o t h in the Pacific (Gran & Angst, 1931; C u p p , 1943; Gotelli, 1971; Guo Yujie, 1981; M a n a b e & Ishio, 1991) a n d in the Atlantic O c e a n (Patten et al., 1963; M a h o n e y & Steimle, 1980; Marshall, 1984). In 1977 the s p e c i e s w a s first r e c o g n i z e d in w a t e r s off t h e s o u t h e r n coast of E n g l a n d w a t e r s (Boalch & Harbour, 1977a). Since t h e n it has s p r e a d t h r o u g h the w h o l e N o r t h Sea.

MATERIAL A N D M E T H O D S

Distribution a n d a b u n d a n c e of Coscinodiscus wailesii G r a n & A n g s t w a s a n a l y z e d in the North S e a w i t h i n the p r o j e c t studies Z I S C H I (1986/87: circulation a n d T r a n s f e r of Pollutants in t h e N o r t h Sea), Z I S C H II (1988/89: C i r c u l a t i o n a n d T r a n s f e r of Pollutants in the G e r m a n Bight), PRISMA (1991/92: Transport, Transfer a n d T r a n s f o r m a t i o n Processes in the G e r m a n Bight), TUVAS (1991/92: Transport, C o n v e r s i o n a n d V a r i a b i l i t y of Pollu- tants a n d N u t r i e n t s in the G e r m a n Bight), a n d O P T I N O M (1991/92: I m p r o v e m e n t of the N o r t h Sea Monitoring). A d d i t i o n a l d a t a w e r e o b t a i n e d d u r i n g a ten y e a r p e r i o d of studies (1982-1992) in t h e o u t e r S c h e l d t e s t u a r y n e a r B r e s k e n s (The N e t h e r l a n d s ) .

D u r i n g the Z I S C H I p r o g r a m m e , the p h y t o p l a n k t o n w a s a n a l y z e d in t h e e n t i r e N o r t h S e a at 131 stations. In the following 3 y e a r s (11/88-4/92) the G e r m a n Bight w a s s a m p l e d with 18 grids of 17-51 stations. T h e s e s t u d i e s c o n c e n t r a t e d on the m e a s u r e m e n t of the h e a v y m e t a l c o n t e n t in the p h y t o p l a n k t o n a n d on t h e r e c o r d i n g of the s p e c i e s composi- tion of the p r i m a r y p r o d u c e r s .

S a m p l e s for p h y t o p l a n k t o n a n a l y s i s w e r e c o l l e c t e d at 2 to 4 d i f f e r e n t d e p t h s w i t h rosette s a m p l e r s (CTD), fixed w i t h b u f f e r e d formol a n d p r o c e s s e d b y the t e c h n i q u e of the i n v e r t e d m i c r o s c o p e w i t h i n 3 m o n t h s after s a m p l i n g . Cell v o l u m e a n d c a r b o n c o n t e n t of the cells w e r e c a l c u l a t e d , b a s e d on q u a n t i t a t i v e d a t a of p l a n k t o n a n a l y s i s a c c o r d i n g to Rick (1990) a n d S t r i c k l a n d & Parsons (1972).

To a v o i d m e t a l c o n t a m i n a t i o n from the r e s e a r c h vessel, s a m p l e s for h e a v y m e t a l d e t e r m i n a t i o n of the p l a n k t o n w e r e t a k e n b y r u b b e r d i n g h y in the surface l a y e r b y u s i n g a m o d i f i e d (no m e t a l parts) p l a n k t o n n e t (55 gm m e s h size). Direct m i c r o s c o p i c control of t h e s e s a m p l e s followed, in o r d e r to e s t i m a t e the p e r c e n t a g e of p h y t o p l a n k t o n content. A n aliquot of e a c h n e t s a m p l e w a s fixed w i t h b u f f e r e d formol for s u b s e q u e n t q u a n t i t a t i v e p l a n k t o n analysis.

T h e cells w e r e c o n c e n t r a t e d on Sartorius cellulose nitrate tilters (pore s i z e 0.2 gin) for trace m e t a l analysis, if the p h y t o p l a n k t o n c o n t e n t c o n s i s t e d of over 90 % of the entire seston. For p u r i f i c a t i o n p r o c e d u r e of filters s e e M a r t (I979a).

(3)

I m p o r t a n c e a n d a b u n d a n c e of Coscinodiscus wailesii in the G e r m a n Bight 357

c o n d i t i o n i n g the filter s a m p l e s in an o x y g e n p l a s m a processor (Plasma T e c h n i c s m o d e l 200G). For p r e v e n t i o n of c o n t a m i n a t i o n a n d other risks in a c c u r a c y in v o l t a m e t r i c trace m e t a l analysis s e e M a r t (1979a, b, c, 1982) and M a r t et al. (1980).

A d d i t i o n a l l a b o r a t o r y data w e r e o b t a i n e d u s i n g b a t c h and s e m i c o n t i n u o u s cultures of Coscinodiscus waiiesii. T h e clone u s e d was isolated from a net p l a n k t o n s a m p l e t a k e n from the o u t e r S c h e l d t estuary n e a r B r e s k e n s (The N e t h e r l a n d s ) in F e b r u a r y 1991. T h e n o n - a x e n i c u n i a l g a l stock cultures w e r e k e p t b o t h in 20-ml Scinti-Vials a n d 1-1 Duran- bottles at 12 ~ a n d a q u a n t u m scalar i r r a d i a n c e of 18 ~E m -2 s -1 (cool w h i t e f l u o r e s c e n t tubes, Phillips T L M 33 RS/65) in a 12 : 12 h l i g h t / d a r k cycle. E x p e r i m e n t s w e r e carried out in Celstir bottles (Zinsser) at the s a m e l i g h t / d a r k cycle a n d a light l e v e l of 50 ~E m -2 s -1 (LI-COR LI-185B Q u a n t u m m e t e r with LI-190SB Q u a n t u m sensor). T h e cultures w e r e stirred using a Wheaton-Biostir-6 system (Zinsser). Dilution rates v a r i e d from 0.2 to 0.5 d a y - 1.

M e d i a w e r e p r e p a r e d u s i n g 0.2-gm m e m b r a n e - f i l t e r e d North Sea w a t e r from the G e r m a n Bight (4/91). T h e salinity r a n g e d from 31 to 32 %0. T h e m e d i a w e r e e n r i c h e d with nutrients a c c o r d i n g to Von Stosch & D r e b e s (1964). N and P w e r e a d d e d at 0.1, Si at 1.0 strength, s p e c i f i e d in ~mol d m - 3 : N: 56, P: 30, Si: 35, Fe: 1.0, Mn: 0.1. T h e v i t a m i n s B12, biotine, and t h i a m i n e w e r e a d d e d to final c o n c e n t r a t i o n s of 50 ug dm -3. In o r d e r not to c h a n g e the c o m p l e x i n g capacity of the s e a w a t e r , t h e r e was no addition of c h e l a t i n g agents. Relative c o m p l e x i n g capacity (RCC) w a s m e a s u r e d by a v o l t a m p e r o m e t r i c m e t h o d u s i n g l e a d as indicator m e t a l ( c o m p l e x i n g time 10 min; 0.5 gg Pb d m -3 10 min ~_RCC -- 1; Rick, 1990).

T h e t r e a t m e n t of s a m p l e s for h e a v y m e t a l analysis of the cultured a l g a e w a s the s a m e as in field samples. H e a v y m e t a l contents of the m e d i a w e r e a n a l y z e d u s i n g the D P A S V m e t h o d after UV photolysis a c c o r d i n g to M a r t (1979c). Bioconcentration factors (BCF) w e r e c a l c u l a t e d b a s e d on the m e t a l c o n c e n t r a t i o n b o t h in the m e d i u m a n d t h e algae.

D o u b l i n g times w e r e c a l c u l a t e d from c h a n g e s in cell n u m b e r during e x p o n e n t i a l growth.

RESULTS

N o r t h S e a

Figure 1 displays the distribution of Coscinodiscus wailesii d u r i n g t h e Z I S C H

s u m m e r cruise in M a y - J u n e 1986, as well as the o b s e r v a t i o n s of some o t h e r authors. Only 10 of the 131 stations s a m p l e d s h o w e d an o c c u r r e n c e of this species. It w a s f o u n d m a i n l y in the n o r t h e r n parts of the s a m p l i n g a r e a n e a r the Orkney, Shetland, a n d F a r o e islands. C. wailesii o c c u r r e d in the s o u t h e r n part of the N o r t h S e a only at two stations in t h e most o u t e r part of the G e r m a n Bight. D u r i n g the Z I S C H s u m m e r c a m p a i g n , the s p e c i e s was not stock-forming. It w a s f o u n d in a salinity a n d t e m p e r a t u r e r a n g e from 34.41-35.28 %0 S

a n d 6.84-8.92 ~ respectively.

S c h e l d t e s t u a r y

(4)

358 H . - J , R i c k & C.-D. D f i r s e l e n

9

H

6 0 ~ A . ~ 9

5 8 ~ ~

5 6 ~

54. ~

5 2 ~

5 0 ~

0

,A

|

- 8 ~ - 6 ~ - 4 ~ - 2 ~ 0 ~ 2 ~ 4 ~ 6 ~ 8 ~ 10 ~

Fig. 1. Distribution pattern of Coscinodiscus wailesii G r a n & A n g s t in the North S e a a n d adjacent waters. This study's data a n d the data of other authors are given in one g e n e r a l m a p . Small filled triangles: ZISCH c a m p a i g n M a y - J u n e 1986, Rick (1990); large filled triangle: this study; circled triangle: 10 y e a r period (1982-1992), Scheldt estuary; fiUed squares: Rince & P l a u m i e r (1986); small o p e n circles: Robinson et ai. (1980); o p e n triangles: Boalch & H a r b o u r (1977a); o p e n circle 1: Gillbricht in Rince & Plaumier (1986); o p e n circle 2: Drebes in Rince & Plaumier (1986); o p e n circle 3:

(5)

I m p o r t a n c e a n d a b u n d a n c e of C o s c i n o d i s c u s wailesii in t h e G e r m a n B i g h t 359

r e c o g n i z e d i n 1982. M o r e t h a n 50 % of t h e s a m p l e s c o n t a i n e d C. wailesn'. It w a s m o s t a b u n d a n t f r o m S e p t e m b e r to M a r c h i n s a l i n i t y a n d t e m p e r a t u r e r a n g e s of 2 4 - 3 2 %~ S a n d 0 - 2 0 ~ N o p r o o f e x i s t s of its o c c u r r e n c e i n e a r l y s u m m e r ( J u n e / J u l y ) . In m o s t c a s e s , w e f o u n d C. w a i l e s i i a c c o m p a n i e d b y Thalassiosira p u n c t i g e r a Castr. a n d Thalassiosira h e n d e y i H a s l e & Fryxell, t w o o t h e r i n t r o d u c e d s p e c i e s .

G e r m a n B i g h t

T a b l e 1 s h o w s t h e a b u n d a n c e a n d b i o m a s s d e v e l o p m e n t of C. wailesii d u r i n g t w o c a m p a i g n s (18 c r u i s e s ) of i n v e s t i g a t i o n (1: 1 1 / 8 8 - 5 / 8 9 ; 2: 4 / 9 1 - 4 / 9 2 ) i n t h e G e r m a n B i g h t . F i g u r e s 2 - 7 d e s c r i b e t h e a c c o m p a n y i n g s p a t i a l d i s t r i b u t i o n s . T h e d a t a p o i n t o u t t h a t C o s c i n o d i s c u s w a i l e s i i h a s e s t a b l i s h e d i t s e l f i n t h e G e r m a n B i g h t a r e a d u r i n g t h e l a s t d e c a d e . In s o m e p e r i o d s ( 1 1 / 8 8 - 3 / 8 9 a n d 8 / 9 1 - 1 0 / 9 1 ) m o r e t h a n 90 % of t h e p h y t o p l a n k -

Table 1. A b u n d a n c e and biomass of Coscinodiscus wailesii in the German Bight during the programs ZISCH II, PRISMA, TUVAS and OPTINOM. The campaign period, the n u m b e r of the s a m p l e d stations, the p e r c e n t a g e of stations in which C. wailesii was stock-forming a n d m e a n /

maximum biomass levels in carbon units for the whole water column are given

Cruise Sampled Percent- Biomass (rag C m -3)

stations age" Max.* " Mean* " *

ZISCH II

11/88 23 39 314 175.9

12/88 23 22 142 69.1

01/89 17 71 170 45.9

02/89 17 41 382 141.0

03/89 8 63 1270 475.3

04/89 17 29 178 92.7

05/89 20 20 357 113.6

PRISMA

04/91 50 0 0 0

08/91-1 51 52 1004 142.3

08/91-2 33 48 550 212.3

08/91-3 44 34 812 179.2

08/91-4 42 47 1705 348.4

08/91-5 51 41 1325 482.6

TUVAS-OPTINOM

09/91 20 85 421 220.0

10/91 20 80 445 131.1

01/92 18 44 29 14.0

03/92 18 83 210 80.2

PRISMA

04/92 42 59 551 96.4

" p e r c e n t a g e of the sampled stations w h e r e Coscinodiscus wailesii was stock-forming. * * maximum carbon content of Coscinodiscus waflesii (rag C m -3) for this particular cruise. * * ' m e a n carbon content of Coscinodiscus wailesii (rag C m -3) at e a c h station w h e r e this species

(6)

360 H.-J, R i c k & C.-D. D L i r s e l e n

55" 0 0 ' -

Coscinodiscus

wailesii

FS VALDIVIA

9

D

s

0 0

00

Cb

d

(D

Z

54" 3 0 ' -

54" 0 0 ' -

53" 3 0 '

0

Circles: 1 1 / 8 8

Blank bars: 1 2 / 8 8

[ ]

o ~

~.) Q,

0,

200 pg C 1-1

6 ~ 30" 7 ~ 00" 7 ~ 3 0 ' 8 ~ 0 0 ' 8 ~ 3 0 ' 9 ~ 00'

Fig. 2. Spatial distribution and biomass of Coscinodiscus waflesii in the German Bight. Results of two

winter cruises in N o v e m b e r a n d D e c e m b e r 1988. The biomass data are given as m e a n c a r b o n values I~g C d m -3) for the u p p e r layer (0-20m) of the w a t e r column. Symbol size compares to the biomass

value (see l e g e n d lower right)

t o n b i o m a s s w a s b o u n d i n t h i s s p e c i e s . W e f o u n d C. wailesii i n a t e m p e r a t u r e a n d s a l i n i t y r a n g e f r o m 2 . 0 - 1 7 . 0 ~ a n d 2 7 - 3 4 %0 S, r e s p e c t i v e l y .

I n w i n t e r , t h e s p e c i e s w a s m e r e l y p r e s e n t n e a r t h e o u t e r b o r d e r s of t h e G e r m a n B i g h t w i t h l o w b i o m a s s l e v e l s (Figs 2, 5, 7). S p r i n g s h o w e d a r i c h e r a b u n d a n c e i n t h e w e s t e r n r e g i o n ; t h e s p e c i e s w a s a b s e n t i n t h e a r e a of t h e E l b e R i v e r p l u m e ( F i g s 4, 6, 7). I n s u m m e r a n d e a r l y a u t u m n , t h e r e w e r e r e c o r d s of C. wailesii i n t h e c o a s t a l a n d e a s t e r n p a r t of t h e G e r m a n B i g h t (Fig. 5), w h i l e it w a s m o r e a b u n d a n t a t t h e w e s t e r n a n d n o r t h e r n b o r d e r s of t h e s u r v e y r e g i o n i n l a t e a u t u m n (Fig. 5).

(7)

I m p o r t a n c e a n d a b u n d a n c e of Coscinodiscus wailesii in the G e r m a n Bight 361

On oO O~

~D U_

--D

55" 00'

54" 30"

I I I I I 1 t

C o s c i n o d i s c u s w G i l e s i i

F S V A L D I V I A , F S G A U S S

Circles: 1/89 Blank bars: 2/89

i i i i [ L ~ i

[]

0

-

54" 00'

9

5 3 " 3 0 ' ~ I i I 1 ~ ~ I I I I " /

6 ~ 30' 7 ~ 00" 7 ~ 30' 8 ~ 00" 8 ~ 30' 9 ~ 00'

Fig. 3. Spatial distribution and biomass of Coscinodiscus wailesii in the German Bight. Results of two

winter cruises in January and February 1989. The biomass data are given as mean carbon values (~g C d m -3) for the upper layer (0-20m) of the water column. Symbol size compares to the biomass value

(see legend lower right)

a b u n d a n t in the coastal a r e a of the G e r m a n Bight (8.10~176 54.13~176 9

stations) w i t h i n c r e a s i n g biomass during the s u r v e y p e r i o d (15th-29th August). It was

a c c o m p a n i e d by the native species Coscinodiscus granii Gough. For the a r e a m e n t i o n e d ,

m e a n b i o m a s s d o u b l i n g - t i m e s for b o t h s p e c i e s w e r e c a l c u l a t e d on the basis of the i n t e g r a t e d b i o m a s s v a l u e s from the u p p e r l a y e r of the w a t e r c o l u m n (0-20 m). No significant g r o w t h of C. granii was d e t e r m i n e d w h i l e C. wailesii s h o w e d d o u b l i n g - t i m e s of 70 h.

F i g u r e 7 shows the spatial distribution a n d biomass of the r e l a t e d s p e c i e s Coscinodis-

(8)

362 H.-J. Rick & C.-D. Dfirselen

ob oo ob

L.

C" C~

55" 0 0 '

54" 30"

54" 00"

Coscinodiscus wailesii

FS VALDIVIA, FS VICTOR H E N S E N

Circles:

,3/89

(~ "~.~("~

Blank bars:

4/89 ~

Q

II

53" 50' " ~ " ~

6 ~ 30' 7 ~ 00' 7" 30' 8 ~ 00' 8" 30' 9 ~ 00'

Fig. 4. Spatial distribution and biomass of Coscinodiscus wailesfi in the G e r m a n Bight, Results of

three spring cruises in March, April and M a y 1989. T h e biomass data are given as m e a n carbon values (~g C d m -3) for the upper layer (0-20m) of the water column. Symbol size compares to the

biomass value (see legend lower right)

cell n u m b e r s differ. C. concinnus e x c e e d s C. wailesfi in the outer bight, w h i l e C. wailesii

is d o m i n a n t i n the East Frisian coastal waters.

B i o c o n c e n t r a t i o n of t r a c e m e t a l s

(9)

I m p o r t a n c e a n d a b u n d a n c e of C o s c i n o d i s c u s wai]esii in the G e r m a n Bight 363

55" 0 0 ' -

Coscinodiscus wailesii

FS VALDIVI/k, FS METEOR

, ii

o 9

9

54" 30" -

1

o

54" 00" s

.<

53" 3 0 ' "~ ~ ~ 2 1 -I

I l i I l J I i l I l 'i ~ I l 6 ~ 3 0 " 7 ~ 0 0 ' 7 ~ 3 0 ' 8 ~ 0 0 ' 8 ~ 3 0 ' 9 ~ 00' Fig: 5. Spatial distribution and biomass of Coscinocfiscus wai]esii in the German Bight. Results of three cruises in summer and autumn (August 1991, September 1991, October 1991). The biomass data are given as mean carbon values (~tg C dm -3) for the upper layer (0-20m) of the water column.

Symbol size compares to the biomass value (see legend lower right)

w h e r e C. waflesii w a s a b u n d a n t , w e r e r e l a t i v e l y h i g h m e t a l contents (Zn, Cu, Cd) in t h e p l a n k t o n found. T h e y w e r e l o c a t e d at the o u t e r distribution b o r d e r of C. wailesii, w h e r e this s p e c i e s w a s m a i n l y a c c o m p a n i e d b y the centric diatom R h i z o s o l e n i a s h r u b s o l e i Cleve.

T h e results of s u b s e q u e n t l a b o r a t o r y e x p e r i m e n t s c o n c e r n i n g the b i o c o n c e n t r a t i o n of zinc a n d c o p p e r in C. wailesii are s h o w n in T a b l e 4.

D I S C U S S I O N

(10)

364 H.-J. R i c k & C.-D. D s

T a b l e 2. Bioconcentration factors (BCF} of zinc a n d copper m natural p h y t o p l a n k t o n populations (August 1991, G e r m a n Bightl. The relative complexing capacity (RCC) of the s e a w a t e r varied from 0.8 to 1.5 d u r i n g the cruise. BCF. zinc and copper content of the seawater, s t a n d a r d deviations.

m i n i m u m and m a x i m u m value are given

M e a n Zn content, water: 472 z 237 n g Zn k g -1

Minimum value: 232 n g Zn k g -1

M a x i m u m value: 1025 n g Zn k g -~

Phytoplankton BCF S t a n d a r d M i n Max. n

zinc deviation value value

C. waflesii 29300 25000 7300 62200 12 a b u n d a n t

O t h e r s p e o e s 189900 160300 18000 562100 9

a b u n d a n t

M e a n Cu content, water: 390 z 74 ng Cu kg -1

M i n i m u m value: 306 ng Cu kg -1

M a x i m u m value: 624 ng Cu kg -1

Phytoplankton BCF S t a n d a r d Min. Max. n

copper deviation value value

C. waflesii 4430 3790 980 11460 12 a b u n d a n t

O t h e r species 15610 11340 2050 29940 9

a b u n d a n t

m a p . C. w a i l e s i i w a s d i s c o v e r e d i n 1977 b y B o a l c h & H a r b o u r (1977a) i n t h e C e l t i c S e a , t h e E n g l i s h C h a n n e l ( R i n c e & P l a u m i e r , 1986) a n d t h e s o u t h e r n p a r t of t h e I r i s h S e a ( R o b i n s o n e t al., 1980). S i m o n s e n (in R i n c e & P l a u m i e r , 1986) s t a t e d t h a t t h e s p e c i e s o c c u r s a t n e a r l y all N o r t h S e a c o a s t l i n e s .

T h e d a t a of B o a l c h & H a r b o u r ( 1 9 7 7 a ) a n d R o b i n s o n e t al. (1980), w h o r e c o r d e d h i g h b i o m a s s e s of C. w a i l e s i i i n w i n t e r a n d s p r i n g i n i n s h o r e w a t e r s , w h i l e c e l l n u m b e r s d e c l i n e d t o w a r d s M a y , c o r r e s p o n d w e l l w i t h o u r f i n d i n g s i n t h e S c h e l d t a r e a a n d t h e G e r m a n B i g h t .

T h e o b s e r v e d w i d e r a n g e of s a l i n i t y a n d t e m p e r a t u r e for s p e c i e s o c c u r r e n c e c o n f i r m s t h e r e p o r t s f r o m R i n c e & P l a u m i e r (1986), w h o s t a t e d t h a t C. w a i l e s i i o c c u r r e d i n o p e n o c e a n , a s w e l l a s i n e s t u a r y a n d i n s h o r e , r e g i o n s .

(11)

I m p o r t a n c e a n d a b u n d a n c e of Coscinodiscus wailesii in t h e G e r m a n B i g h t 365 Table 3. Bioconcentration factors (BCF) for the trace metals copper and zinc. Coscinodiscus waflesii in semicontinuous cultures (dilution rate 0.5-0.2 d 1, 12 ~ light dark cycle: 12:12 h; 50 IrE m -z s 1). M e a n biomass doubling-times, ranges of the zinc, copper content, and RCC (relative complexing

capacity) of the media are given, n = n u m b e r of data points

Range of Cu content (medium): 1-8 ~g Cu kg -1

Range of Zn content (medium): 3-5 [tg Zn kg-1

RCC: 0.8 A 0.4 gg Pb kg -1 10 rain

Doubling-time: 107.9 • 37.2

Trace metals BCF Standard Min. Max. n

deviation value value

Copper 2700 910 1000 4790 65

Zinc 5890 1660 2200 9710 67

Table 4. Bioconcentration factors (BCF) and volume-related metal content of various North Sea phytoplankton species in semicontinuous cultures with literature references

COPPER ZINC

Species Content Content BCF Content Content BCF Author

m e d i u m cells m e d i u m cells

( n g k g -1) (10 1o ( n g k g -1) (10 - l ~

ng am -3) ng Mm -3)

Scrippsiella 450 50 11200 6300 450 7070 Corves

trochoidea _+14 • 3100 + 80 _ + 1 2 6 0 (1992)

Gyrodinium 620 120 19350 5800 460 8000 Rick

aureolum -_4-_ 10 • 1600 (1990)

Phaeocystis 1130 185 16390 9500 1300 13700 Rick

globosa • 20 (1990)

Micromonas 3800 830 21800 14600 325 2200 Rick

pusilla -+ 195 -+ 5100 • 180 • 1200 {1990)

Thalassiosira 480 66 13700 2800 134 4820 Corves

rotula -+ 4 -+ 830 • 28 _ + 1 0 3 0 (1992)

Thalassiosira 780 60 7400 8840 370 4180 Kleinert

punctigera + 6 -+ 900 _+ 75 -4- 840 (1987)

(12)

366 H.-J. Rick & C.-D. Diirselen

( ' 4 O )

r

d

55" 0 0 '

54" 30"

I I I I I I I I I I I I ~ J [

Coscinodiscus

wailesii

FS GAUSS, FS ALKOR

I I

Lines: 1/92 Circles: 3/92

0

Q

I i I I I I I I I I I ~ I I I I I 6 ~ 30" 7 ~ 00" 7 ~ 30' 8 ~ 00' 8 ~ 30' 9 ~ 00

Fig. 6. Spatial distribution and biomass of Coscinodiscus wai]esii in the German Bight. Results of two

cruises in winter and early spring 1992. The biomass data are given as mean carbon values (~g C dm -3) for the upper layer (0-20m) of the water column. Symbol size compares to the biomass value

(see legend lower right)

i n v e s t i g a t i o n s in M a y 1986 a n d April 1991 also p r o v i d e d no e v i d e n c e for t h e o c c u r r e n c e of C. wailesn" in the G e r m a n Bight. T h e s e results m a y l e a d to the a s s u m p t i o n that the a p p e a r a n c e of o n e s p e c i e s m a y inhibit t h e o c c u r r e n c e of t h e other. N o e v i d e n c e for an e x c l u d i n g m e c h a n i s m can b e r e v e a l e d , on t h e basis of the data of t h e P R I S M A spring cruise in 1992 (Fig, 7). In this period, b o t h s p e c i e s h a d i d e n t i c a l distribution p a t t e r n s ; only the a r e a s of m a x i m u m cell n u m b e r s differed. T h e g r e a t e r offshore a b u n d a n c e of C. c o n c i n n u s is in a c c o r d a n c e to the p r e d i c t i o n of Baars (1988), w h o m e n t i o n e d d e e p e r w a t e r c o l u m n s a n d h i g h light r e g i m e as g r o w t h conditions f a v o u r e d by C. concinnus.

(13)

I m p o r t a n c e a n d a b u n d a n c e of C o s c i n o d i s c u s w a i l e s i i in t h e G e r m a n B i g h t 367

55" 00'

54" 30'

(-q O ]

5 4 " 0 0 I El.

<

53" 30'

Coscinodiscus wailesii/Cos, concinnus

FS VALDIVIA

|

9

G,

O

6 ~ 30' 7 ~ 00' 7 ~ 30' 8 ~ 00' 8 ~ 30' 9 ~ 00"

Fig. 7. Spatial distribution and biomass of the introduced Coscinodiscus wailesn and the native

Coscinodiscus concinnus in the German Bight during the PRISMA spring cruise in April 1992. The biomass data are given as mean carbon values (~g C dm -3) for the upper layer (0-20m) of the water

column. Symbol size compares to the biomass value (see legend lower right). C. wailesii is displayed

by the unfilled circles, C. concinnus by the crossed circles

a r e g u l a r s e a s o n a l d i s t r i b u t i o n p a t t e r n of t h e s p e c i e s , s i n c e a n y v a r i a b i l i t y in c i r c u l a t i o n , h g h t a n d n u t r i e n t r e g i m e m a y h a v e a s t r o n g i m p a c t o n t h e s p e c i e s ' a n n u a l d e v e l o p m e n t . S o m e q u e s t i o n s r e m a i n to b e a n s w e r e d : (1) W h a t a r e t h e r e a s o n s for t h e s u c c e s s of C o s c i n o d i s c u s w a f l e s i i in t h e N o r t h S e a a r e a ? (2) W h a t is t h e e f f e c t of t h e s p r e a d i n g of C o s c i n o d i s c u s w a f l e s i i on t h e e c o s y s t e m of t h e G e r m a n B i g h t ?

(14)

368 H.-J. Rick & C.-D. Dfirselen

F~

Ob

9

7

~D

9

55 ~ 0 0 '

54 ~ 3 0

54 ~ 0 0

53" 30"

0

0 o

0

, o 0 o

/k ~

o

@~o

o

A - - A

A

A

/k

/k

/k /~

A

/ k

/ k

o

o O a

A

~Xr 1 Zn content

phytoplQnktor

(first grid)

0

,~:s:::=z~ '~' ~ ,g::::~'~".'r.. 0 ~ooo

6 ~ 30' 7 ~ 0 0 ' 7 ~ 3 0 8 ~ 0 0 8 ~ 3 0 ' 9 ~ 0 0 Fig. 8. S p a t i a l d i s t r i b u t i o n of the v o l u m e - r e l a t e d zinc c o n t e n t of 50 ,Ltm n e t p l a n k t o n in the G e r m a n

Bight during the PRISMA summer cruise in August 1991. Symbol size compares to the value of the

zinc content (see legend lower right). Stations with stock-forming occurrence of C. wailesii are

marked by unfilled triangles. For numbered stations compare text

(15)

I m p o r t a n c e a n d a b u n d a n c e of C o s c i n o d i s c u s w a i l e s i i i n t h e G e r m a n B i g h t 369

0 ]

C3~

<

9

" 0 (D

55 ~ 0 0 '

m

I I I I I I I I I I I I ~ I I

o

0

0

A

0

A (

) o A,,o

o

Q

A

A

s

A A

~

A A A

A A A

o

A

A

0

Q

~ ? ~ I Cu content

o

d~

_

53 ~ 30 ~" "1 I I I I I I I • I ~ I I ~ I I 6 ~ 30' 7 ~ 00' 7 ~ 50' 8 ~ 00' 8 ~ 30' 9 ~ 00' Fig. 9. Spatial distribution of the volume-related copper content of 50 gm net p l a n k t o n in the G e r m a n Bight during the PRISMA s u m m e r cruise in A u g u s t 1991. Symbol size compares to the value

of the copper content (see l e g e n d lower right). Stations with stock-forming occurrence of C. wailesii

are m a r k e d by unfilled triangles. For n u m b e r e d stations compare text

(16)

370 H.-J. Rick & C.-D, Diirselen

o~

.(

~D

>

5 5 " 0 0 '

54" .30'

o

A

~

(frst grid)

A

o

o A

.

A A

A A

A A

19A A A

~

f

o

A

A

A

~ ~

- ' M

~,o0

O A A A

o

~

5 3 ~ 3 0 "1 i [ i I

6 ~ 3 0 ' 7 ~ 0 0 ' 7 ~ 3 0 8 ~ 0 0 8 ~ 3 0 ' 9 ~ O0

Fig. 10. Spatial distribution of the volume-related lead content of 50 ~tm net plankton in the German Bight during the PRISMA summer cruise in August 1991. Symbol size compares to the value of the

lead content (see legend lower right). Stations with stock-forming occurrence of C. wailesii are

marked by unfilled triangles. For numbered stations compare text

( c o m p a r e Rabsch & Elbr~chter, 1980) for this c a m p a i g n period. M a y b e a m i c r o n u t r i e n t that is of l e s s e r i m p o r t a n c e for the g r o w t h of C. wailesii t h a n that of C. granii w a s t h e d e t e r m i n i n g factor.

E x p e r i m e n t s c o n d u c t e d by Roy et al. (1989) g i v e a n o t h e r hint for p o s s i b l e r e a s o n s foI

t h e success of C. wailesii, T h e c o p e p o d s T e m o r a longicornis O.F.R. Mfiller a n d Calanu~

(17)

I m p o r t a n c e a n d a b u n d a n c e of C o s c i n o d i s c u s w a i l e s i i in the G e r m a n Bight 371

O~

%

O ~

<

~D

55 ~ 0 0 '

5 4 ~ 5O

5 4 ~ 0 0

53" 30

I

O

31

~

i

@ Q A

A

A

9 o / ~

. ~ r

I

6 ~ 5 0 '

I I I I v I I

A

~ 4 I

Cd c~

( ~

phytoplonkton

(first grid)

A

A

A

A

A

o r

2(

i E I i ~ I i I [ ... I i ~ I

7 ~ 0 0 ' 7 ~ 3 0 ' 8 ~ 0 0 ' 8 ~ 3 0 ' 9 ~ 0 0

Fig. 11. Spatial distribution of the volume-related cadmium content of 50 ~m net plankton in the German Bight during the PRISMA summer cruise in August 1991. Symbol size compares to the value of the cadmium content (see legend lower right). Stations with stock-forming occurrence of

C. wailesii are marked by unfilled triangles. For numbered stations compare text

T h e results of t h r e e y e a r s of r e s e a r c h in the G e r m a n Bight illustrate that C. w a i l e s i i c a n s u p e r s e d e n a t i v e s p e c i e s at times or at least d e c r e a s e their biomass d e v e l o p m e n t . G r a z i n g by c o p e p o d s m a y be r e d u c e d , a n d mass d e v e l o p m e n t of C. wa//es/i m a y t h e n h a v e c o n s e q u e n c e s for the following trophic levels.

(18)

372 H . - J . R i c k & C.-D. D f i r s e l e n

l o w t e m p e r a t u r e s in w i n t e r . In s p r i n g , d e c o m p o s i t i o n of t h e o r g a n i c c o m p o n e n t s c a u s e d o x y g e n d e f i c i t s in t h e b o t t o m w a t e r . C o n s e q u e n c e s of o x y g e n d e p l e t i o n for b e n t h i c o r g a n i s m s a r e w i d e l y k n o w n , e v e n for t h e a r e a of t h e o u t e r G e r m a n B i g h t (v. W e s t e r n h a - g e n & D e t h l e f s e n , 1983; R a c h o r & A l b r e c h t , 1983; R a c h o r , 1985). F o r t h e i n n e r G e r m a n B i g h t , s u c h e m i n e n t o u t c o m e is r a t h e r u n l i k e l y s i n c e v e r t i c a l c i r c u l a t i o n is i n i t i a t e d f r e q u e n t l y b y t i d a l m i x i n g p r o c e s s e s .

Acknowledgements. M. Kr/imer, S. Rick, Dr. U. Tillmann, M. Klerx, V. Bahs, Dr. M. Mfiller, J. Corves a n d H. A. Heinz are cordially t h a n k e d for their participation in cruises, running laboratory experi- m e n t s and phytoplankton analysis. Thanks are also due to Dr. M. Haarich (BSH, Hamburg) and his group for phytoplankton sampling in the period S e p t e m b e r 1991 to March 1992 d u r i n g TUVAS and OPTINOM programmes. This work was partly f i n a n c e d by the Bundesministerium ffir Forschung und Technologie u n d e r contract Nos. MFU 0545, MFU 0578/7 and O3F0556A.

L I T E R A T U R E C I T E D

Atetsee, L. & Rick, H. J., 1990. Phytoplankton. In: Zirkulation und Schadstoffumsatz in der Nordsee. Hrsg. von A. Moll & G. Radach. Institut fiir M e e r e s k u n d e , Univ. Hamburg, H a m b u r g , Teilprojekt G5.

Aletsee, L., Rick, H. J., D6rselen, C. D. & Becker, V., 1992. Schadstoffumsatz im Phytoplankton. In: Prozesse im Schadstoffkreislauf Meer-Atmosph/ire: Okosystem Deutsche Bucht (PRISMA). Hrsg. yon J. Stindermann & S. Beddig. Zentrum ffir M e e r e s - und Klimaforschung, Univ. Hamburg, Hamburg, 2, 168-178.

Baars, J. W. M., 1988. Autecological investigations on marine diatoms. 5: Coscinodiscus concinnus

W. Smith and Rhizosolenia setigera Brightwell. - Hydrobiol. Bull. 22, 147-155.

Bauerfeind, E., Hickel, W., Niermann, U. & W e s t e r n h a g e n , H. von, 1990. Phytoplankton biomass and potential limitation of phytoplankton d e v e l o p m e n t in the southeastern North S e a in spring 1985 and 1986. - Neth. J. Sea Res. 25, 131-142.

Boalch, G. T. & Harbour, D. S., 1977a. Unusual diatom off the coast of south-west England and its effect on fishing. - Nature, Lond. 269, 687-688.

Boalch, G. T. & Harbour, D. S., 1977b. The structure of the valve and girdle of a planktonic

Pleurosigma. - Nova Hedwigia (Beih.) 54, 275-280.

Corves, J., 1992. U n t e r s u c h u n g e n zur S c h w e r m e t a l l b e l a s t u n g des S o m m e r p h y t o p l a n k t o n s in der Deutschen Bucht mit ergfinzenden L a b o r e x p e r i m e n t e n zur Interpretation der Ergebnisse. Dipl.- Arb., TH Aachen, 129 pp.

Cupp, E. E., 1943. Marine plankton diatoms of the w e s t coast of North America. - Bull. Scripps Instn Oceanogr. 5, 1-238.

Drebes, G., 1991. N e u e Planktondiatomeen im Sylter Wattenmeer. - Jber. Biol. Anst. Helgoland

1990, 29-30.

Dfirselen, C. D., 1990. U n t e r s u c h u n g e n zur Schwermetallakkumulation von P h y t o p l a n k t o n g e m e i n - schaften der Deutschen Bucht mit e r g / i n z e n d e n Laborversuchen zur D e u t u n g der Ergebnisse. Dipl.-Arb., TH Aachen. 127 pp.

Gerlach, S., 1992. Ergebnisse der 5. I n t e m a t i o n a l e n Konferenz fiber giftiges marines Phytoplankton. - DGM Mitt. 2/1992. 5-11.

Gotelh, D., 1971. Lagenisma coscinodisci, a parasite of the marine diatom Coscinodiscus occurring in the Puget sound, Washington. - Mycologica 63, 171-174

Gran, H. H. & Angst, E. C.. 1931 Plankton diatoms of the Puget s o u n d - Pubis P u g e t Sound mar. biol. Stn 7, 417-516.

Guo Yujie, 198I. Studies on the planktonic Coscinodiscus of the South Chinas Sea. - Stud. mar. sin.

18, 149-175.

Hagmeier, E., 1991. Phytoplankton bei Helgoland im Sommer 1990. - Jber. Biol. Anst. Helgoland

1990, 43-44.

(19)

I m p o r t a n c e a n d a b u n d a n c e o f C o s c i n o d i s c u s w a i l e s i i i n t h e G e r m a n B i g h t 3 7 3 Kat, M , 1982. Effects of f l u c t u a t i n g s a l i n i t i e s o n t h e d e v e l o p m e n t of Thalassiosira angstii, a d i a t o m

n o t o b s e r v e d b e f o r e in t h e D u t c h c o a s t a l area. - J. m a r . biol. Ass. U.K. 52, 4 8 3 - 4 8 4 .

Kleinert, R., 1987. L a b o r u n t e r s u c h u n g e n z u r B e e i n f l u s s u n g d e r A s s i m i l a t i o n s l e i s t u n g v o n Phaeocys- tis globosa S c h e r f f e l u n d Thalassiosira punctigera Castr. d u r c h die S c h w e r m e t a l l e Kupfer, Zink, Q u e c k s i l b e r u n d C a d m i u m . Dipl.-Arb., T H A a c h e n , 158 pp.

M a h o n e y , J. B. & Steimle, F. W., 1980. P o s s i b l e a s s o c i a t i o n of f i s h i n g g e a r c l o g g i n g w i t h a d i a t o m b l o o m in t h e m i d d l e A t l a n t i c Bight. - Bull. N e w Jers. A c a d . Sci. 25, 18-21.

M a n a b e , T. & Ishio, S., 1991. Bloom of Coscinodiscus wailesii a n d D O deficit of b o t t o m w a t e r in t h e Seto I n l a n d Sea. - Mar. Pollut. Bull. 23, 181-184.

M a r s h a l l , H. G., 1984. P h y t o p l a n k t o n d i s t r i b u t i o n a l o n g t h e e a s t e r n c o a s t of t h e USA. V: S e a s o n a l d e n s i t y a n d cell v o l u m e p a t t e r n for t h e n o r t h e a s t e r n c o n t i n e n t a l shelf. - J. P l a n k t o n Res. 6, 169-193.

Mart, L., 1979a. P r e v e n t i o n of c o n t a m i n a t i o n a n d o t h e r a c c u r a c y risks in v o l t a m m e t r i c t r a c e m e t a l a n a l y s i s of n a t u r a l w a t e r s , h P r e p a r a t o r y s t e p s , filtration a n d s t o r a g e of w a t e r s a m p l e s . - F r e s e n i u s Z. a n a t y t C h e m . 295, 3 5 0 - 3 5 7 .

Mart, L., 1979b. P r e v e n t i o n of c o n t a m i n a t i o n a n d o t h e r a c c u r a c y risks in v o l t a m m e t r i c t r a c e m e t a l a n a l y s i s of n a t u r a l w a t e r s . II: C o l l e c t i o n of s u r f a c e w a t e r s a m p l e s . - F r e s e n i u s Z. analyt. C h e m . 299, 97-102.

M a r t , L., 1979c. E r m i t t l u n g u n d V e r g l e i c h d e s P e g e l s t o x i s c h e r S p u r e n m e t a l l e in n o r d a t l a n t i s c h e n u n d m e d i t e r r a n e n K / i s t e n g e w / i s s e r n . Diss., T H A a c h e n , 354 pp.

Mart, L., 1982. M i n i m i z a t i o n of a c c u r a c y r i s k s in V o l t a m m e t r i c u l t r a t r a c e d e t e r m i n a t i o n of h e a v y m e t a l s in n a t u r a l w a t e r s . - T a l a n t a 29, 1 0 3 5 - 1 0 4 0 .

Mart, L., N f i r n b e r g , H. W. & V a l e n t a , P., 1980. P r e v e n t i o n of c o n t a m i n a t i o n a n d o t h e r a c c u r a c y r i s k s in v o l t a m m e t r i c t r a c e m e t a l a n a l y s i s of n a t u r a l w a t e r s . III. V o l t a m m e t r i c u l t r a t r a c e a n a l y s i s w i t h a m u l t i c e l l s y s t e m d e s i g n e d for C l e a n B e n c h W o r k i n g . - F r e s e n i u s Z. analyt. C h e m . 300, 3 5 0 - 3 6 2 . N a v a r r o , J. N., 1982. A s u r v e y of t h e m a r i n e d i a t o m s of P u e r t o Rico. I. S u b o r d e r s C o s c i n o d i s c i n e a e

a n d R h i z o s o l e n i i n e a e . - B o t a n i c a m a r . 24, 4 2 7 - 4 3 9 .

O s t e n f e l d , C. H., 1908. O n t h e i m m i g r a t i o n of Biddulphia smensis Grey. a n d its o c c u r r e n c e in t h e N o r t h S e a d u r i n g 1 9 0 3 - 1 9 0 7 . - M e d d r K o m m n H a v u n d e r s . (Plankton) 1 (6), 1-44.

O s t e n f e l d , C. H., 1909. I m m i g r a t i o n of a p l a n k t o n d i a t o m into a q u i t e n e w a r e a w i t h i n r e c e n t y e a r s ; Biddulphia s i n e n s / s in t h e N o r t h S e a w a t e r s . - Int. R e v u e ges. Hydrobiol. H y d r o g r . 2, 3 6 2 - 3 7 4 . P a t t e n , B. C., M u l f o r d , R. A. & W a r r i n e r , J. E., 1963. A n a n n u a l p h y t o p l a n k t o n cycle in t h e l o w e r

C h e s a p e a k e Bay. - C h e s a p e a k e Sci. 4, 1-20.

R a b s c h , U. & Elbrfichter, M., 1980. C d a n d Z n u p t a k e , g r o w t h a n d p r i m a r y p r o d u c t i o n in Coscinodis- cus granii c u l t u r e s c o n t a i n i n g low l e v e l s of ceils a n d d i s s o l v e d o r g a n i c c a r b o n . - Mar. Ecol. Prog. Ser. 14, 2 7 5 - 2 8 5 .

Rachor, E. & A l b r e c h t , H., 1983. S a u e r s t o f f m a n g e l i m B o d e n w a s s e r d e r D e u t s c h e n Bucht. - Ver6ff. Inst. M e e r e s f o r s c h . B r e m e r h . 19, 2 0 9 - 2 2 7 .

Rachor, E., 1985. E u t r o p h i e r u n g in d e r N o r d s e e - B e d r o h u n g d u r c h S a u e r s t o f f m a n g e l . - A b h . n a t u r w i s s . Ver. B r e m e n 40, 2 8 3 - 2 9 2 .

Rick, H.-J., 1990. Ein B e i t r a g z u r A b s c h f i t z u n g d e r W e c h s e l b e z i e h u n g z w i s c h e n d e n p l a n k t i s c h e n P r i m ~ i r p r o d u z e n t e n d e s N o r d s e e g e b i e t e s u n d d e n S c h w e r m e t a l l e n Kupfer, Zink, C a d m i u m u n d Blei a u f d e r G r u n d l a g e y o n U n t e r s u c h u n g e n a n n a t f i r l i c h e n P l a n k t o n g e m e i n s c h a f t e n u n d L a b o r e x p e r i m e n t e n m i t b e s t a n d s b i l d e n d e n A r t e n . Diss., T H A a c h e n , 330 pp.

Rince, Y. & P l a u m i e r , G., 1986. D o n n 6 e s n o u v e l l e s s u r la d i s t r i b u t i o n de la d i a t o m 4 e m a r i n e Coscinodiscus wailesii G r a n & A n g s t ( B a c i l l a r i o p h y c e a e ) . - P h y c o l o g i a 25, 7 3 - 7 9 .

R o b i n s o n , G. A., B u d d , T. D., J o h n , A. W. G. & Reid, P. C., 1980. Coscinodiscus nobilis ( G r u n o w ) in c o n t i n u o u s p l a n k t o n r e c o r d s , 1 9 7 7 - 1 9 7 8 . - J. m a r . biol. Ass. U.K. 50, 6 7 5 - 6 8 0 .

Roy, S., Harris, R. P. & Poulet, S. A., 1989. I n e f f i c i e n t f e e d i n g b y Calanus helgolandicus a n d Temora longicornis o n Coscinodiscus wailesii: q u a n t i t a t i v e e s t i m a t i o n u s i n g c h l o r o p h y l l - t y p e p i g m e n t a n d effects on d i s s o l v e d free a m i n o acids. - Mar. Ecol. Prog. Ser. 52, 145-153.

S i m o n i s , W., 1987. P r i m ~ r v o r g / i n g e b e i d e r S o r p t i o n y o n S c h w e r m e t a l l e n , I n s e k t i z i d e n u n d H e r b i z i - d e n in die A n f a n g s g l i e d e r y o n N a h r u n g s k e t t e n . In: B i o a k k u m u l a t i o n in N a h r u n g s k e t t e n . H r s g . y o n K. Lillelund, U. d e H a a r , H.-J. Elster, L. K a r b e , I. S c h w o e r b e l & W. Simonis. V C H , W e i n h e i m , 9 - 3 8 .

(20)

3 7 4 H . - J . R i c k & C . - D . D i i r s e l e n

D i a t o m e e n . IV. Die P l a n k t o n d i a t o m e e Stephanopyxis turris, ihre B e h a n d l u n g u n d E n t w i c k l u n g s - g e s c h i c h t e . - H e l g o l ~ n d e r wiss. M e e r e s u n t e r s , i I, 2 0 9 - 2 5 7 .

Strickland, J. D. H. & P a r s o n s , T. R., 1972. A p r a c t i c a l h a n d b o o k of s e a w a t e r a n a l y s i s . - Bull. Fish. Res. Bd C a n . 167, 1-310.

T a n g e n , K., 1977. B l o o m s of Gyrodinium aureolum in n o r t h E u r o p e a n w a t e r s , a c c o m p a n i e d b y m o r t a l i t y i n m a r i n e o r g a n i s m s . - S a r s i a 63, 1 2 3 - 1 3 3 .

Figure

Fig. 1. Distribution pattern of Coscinodiscus wailesii Gran & Angst in the North Sea and adjacent waters
Table 1. Abundance and biomass of Coscinodiscus wailesii in the German Bight during the programs ZISCH II, PRISMA, TUVAS and OPTINOM
Fig. 2. Spatial distribution and biomass of Coscinodiscus waflesii in the German Bight
Fig. 3. Spatial distribution and biomass of Coscinodiscus wailesii in the German Bight
+7

References

Related documents

The correlation results shown in panels c and e for u and v , respectively, still show the characteristics of geostrophic balance over the domain scale [as highlighted by the

The paper is discussed for various techniques for sensor localization and various interpolation methods for variety of prediction methods used by various applications

For example, under Policy and Legal issues: A= existing National SDI coordinating body, B= good Policy establishing NGDI coordinating Agency, C= available NGDI Champion

Also, both diabetic groups there were a positive immunoreactivity of the photoreceptor inner segment, and this was also seen among control ani- mals treated with a

Мөн БЗДүүргийн нохойн уушгины жижиг гуурсанцрын хучуур эсийн болон гөлгөр булчингийн ширхгийн гиперплази (4-р зураг), Чингэлтэй дүүргийн нохойн уушгинд том

19% serve a county. Fourteen per cent of the centers provide service for adjoining states in addition to the states in which they are located; usually these adjoining states have

Field experiments were conducted at Ebonyi State University Research Farm during 2009 and 2010 farming seasons to evaluate the effect of intercropping maize with

Aptness of Candidates in the Pool to Serve as Role Models When presented with the candidate role model profiles, nine out of ten student participants found two or more in the pool