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    The publication of Harmful Algae News is sponsored by the Spanish Institute of Oceanography, Vigoand the Institute of Biology, University of Copenhagen.

    The Intergovernmental Oceanographic Commission of UNESCO

    HARMFUL ALGAE NEWSAn IOC Newsletter on toxic algae and algal blooms

    No. 28

    August 2005

    (Contd on p.3)

    SEED: A new EU-US collaboration on HABs

    Detection of toxic Alexandrium catenella (Whedon &Kofoid) Balech in clam production zone of North Lakeand Channel, Tunisia


    Fig. 2. Alexandrium catenella: (a) microphotograph with phase contrast; (b) microphotograph with epifluorescence, ventral view; (c) dorsal view;(d) Po, 1 and Sa; (e) sulcal plates; (f) apical plates of epitheca; (e) Hypotheca.

    The word SEED is not an acronymor abbreviation; it directly refersto seed as produced by plants. However,the indication SEED refers to a newproject entitled Life cycle transforma-tions among HAB species, and the en-vironmental and physiological factorsthat regulate them, for which we do not

    want an acronym.The project is funded by the Global

    Change and Ecosystems Programme ofthe European Commission and the U.S.National Science Foundation. SEEDstarted in March 2005 and will continuefor three years. SEED is endorsed bythe Global Ecology and Oceanography

    of Harmful Algal Blooms programmeof the Intergovernmental Oceano-graphic Commission of UNESCO(GEOHAB) as a Targeted ResearchProject.

    Two coordinators, a steering com-mittee, and 12 partners make up the

    (Contd on p.2)

    A dozen species of Alexandriumhave been identified in the Bay of Tu-nis, of which two are toxic, A.tamarense and A. minutum [1]. Duringour monitoring of the production zones

    of bivalve molluscs in northern Tuni-sia, A. catenella was detected for thefirst time in the Tunis Channel in Au-gust 1997. This species seems to be welladapted to the Mediterranean, and may

    have been introduced with ballast wa-ter [2]. In addition, these are the kindsof ecosystem, estuarine and lagoonal,which are most vulnerable to invasions[2].

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    In the Mediterranean, the first ap-pearance of A. catenella dates from1983 along the Catalan coast [3], andits distribution gradually extended alongthe northwest Mediterranean coast withrecurrent blooms during the period 1997to 1999 in the port of Barcelona, andwith associated production of paralytictoxins [4]. Toxic episodes due to thepresence of gonyautoxins andsaxitoxins in Ltang de Thau are attrib-uted to A. tamarense with A. catenellaalso suspected [5]. The latter species hasalso been noted in Sardinian waters(Tyrrhenian Sea) [6].

    The present report follows the an-nual pattern of this toxic species in the

    Fig. 1. Sampling stations in shellfish production area of North lake and Channel of Tunis.



    Gulf of Tunis

    Channel of Tunis

    North lake of Tunis

    T STEG1


    1 km

    ChekliTunis T1

    T Khreddine1

    T Rads2

    South lake of Tunis

    North Lake and Channel of Tunisia (Fig.1) where the main resources of the clamTapes decussatus are concentrated.These two sites have been monitoredfor toxic planktonic microalgae since1996 [7].

    The North Lake of Tunis was ear-lier marked by the presence of recur-rent green tides of Ulva lactuca, andimportant ecological changes have oc-curred in the last dozen years follow-ing restoration works which were madein the period 1984 to 1988. In particu-lar, there has been a net increase inmacrophyte diversity, and marinephanerogams have appeared [8].Among the toxic species mentioned in

    the clam productionzones in the NorthLake and Channel,only species produc-ing diarrhetic toxins,Dinophysis spp andProrocentrum lima,have previously beendetected [9, 10]. Thenavigation channel isstrongly perturbedby anthropogenicpollution due to theexistence of threeports, with a directimpact on thebenthic macrofaunawhich may extend asfar as the adjacentGulf of Tunis [11]. Afirst appearance ofred water due to abloom of Noctilucascintillans was re-corded in March

    2003 along the southwest coast of theGulf.

    The characteristic morphology of A.catenella is shown in Fig. 2. These cellsare solitary, and rarely seen in chainsor pairs. Total length varies from 25 to32.5 m, and the transverse diameterfrom 19 to 32 m. The epitheca is veryfragile relative to the hypotheca, whichsometimes lacks the pore at the level ofplate Sp. This species is found at cer-tain times of the year (March 2005) ac-companied by Scripsiella trochoideaand Gonyaulax spinifera. Differentia-tion between these cells is made bymeans of epifluorescent microscopyafter staining the cells with calcofluor.

    Annual variations in the abundanceof A. catenella above the critical levelof 500 cells/L have rarely been foundexcept in June in the Channel of Tunis,and in two periods, December and Feb-ruary to March, in the North Lake (Fig.3). Estimated maximum concentrationsare respectively 1300 cells/L in theChannel (T2) in March 2005 and in June2004, and 1000 cells/L in the NorthLake (T1 Chikly).

    It is still too early to state that thisspecies is increasing in abundance in theclam production zones in the NorthLake and Channel of Tunis. Our futurestudies should allow us to follow theevolution of A. catenella which has beendetected since its first appearance.


    1. Daly Yahia-Kfi, O. et al., 2001. Oceanol. Acta29: S17- S25.

    2. Wyatt, T. & J.J. Carlton, 2002. CIESMworkshop Monographs 20: 41- 46.

    3. Margalef, R. & M. Estrada, 1987. Investig.Pesq. 51: 121-140.

    4. Vila, M. et al., 2001. Mar. Ecol. Prog. Ser. 222:73-83.

    5. Masselin, P. et al., 2001. Proc. 9th Int. Conf.Harmful Algal Blooms: 26-29.

    6. Lugli, A. et al., 2003. Bocconea, 16(2): 1045-1051.

    7. Turki, S. 2004. Bull. INSTM 31 (in press).8. Trabelsi, E.B. et al., 2001. MEDCOAST 01, 2:

    945-952.9. Turki, S. & A. El Abed, 1999. Bull. INSTM, 11:

    165-174.10. Turki S. & A. El Abed, 2001. Harmful Algae

    News 22: 10.11. Zammouri N. et al., 2001. MEDCOAST 01, 2:


    S. Turki & N. Balti, Institut Nationaldes Sciences et Technologies de laMer, 2016 la Goulette, Tunisia.Email:

    (Contd from p. 1)








    F1 F4 M3 A1 A4 M3 J2 Jl4 S1 O4 N4 D3 J2 J'4 F3 M2


    T1Steg T1Chikly T1 Kherredine









    F1 F3 M1 M3 M4' A2 A4 M2 M4 J2 Jl2 A2 S1 O1 N1 N4


    T2Rads T2Canal

    Fig. 3. Concentrations of A. catenella (cells/L) in the clam productionzone in the North Lake and Channel of Tunis (February 2004 - March2005).

    North Lake of Tunis

    Channel of Tunis





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    consortium of SEED and include sci-entists from 7 European countries andthe USA.

    SEED aims to understand to whatextent environmental and physiologi-cal factors may influence the non-veg-etative stages of the life cycles of harm-ful algal bloom (HAB) species, therebycontributing to the increase in harmfulalgal blooms (HAB) in European ma-rine, fresh, and brackish waters. SEEDwill focus on the life histories of someof the most relevant HAB species inEurope.

    The areas to be studied comprisethe regions bordering coastal sites in theWestern Mediterranean Sea, AtlanticOcean, North Sea, Baltic Sea, andSwedish lakes. All of these regions haveheavy anthropogenic influences: fish-eries, urban development, aquacultureand tourism. All are subject to the fre-quent occurrence of HABs, with a va-riety of detrimental impacts includinghuman intoxications, closure of shell-fish farms, water discoloration causinga negative impact on tourism, etc.

    The approach of SEED is compara-tive, ranging from species to ecosystemlevels. Despite considerablephylogenetic distance, many morpho-logical and physiological traits of HABspecies are convergent and common.

    The specific objectives are:1. To characterize and quantify the

    different stages of the life cycle in abloom development of selected HABspecies in comparative environments.

    2. To characterize the physiologi-cal mechanisms and tolerances under-lying dormancy stages/cysts, spores andakinetes, their formationand germination for key HAB species.

    3. To explore the mating interac-tions of non-toxic and toxic HAB spe-cies to better understand the nature ofspecies invasions or dispersions and toevaluate the use of non-toxic strains asa possible mitigation strategy in HABs.

    4. To quantify the flux of cells ofkey HAB species in different areas fromand to the sediments.

    5. To investigate the role of sedi-mentary dynamics in the preservation,accumulation and dispersion of dor-mant stages.

    6. To explore methods to identify

    specific life cycle stages of key HABspecies through molecular or immuno-logical techniques.

    7. To use the newly acquired knowl-edge in simple numerical models toverify the relevance of life history fea-tures and to develop or refine predic-tive and conceptual models of bloomdynamics for selected HAB species, tak-ing into account life-history.

    8. To determine the role of dor-mancy stages of HAB species in differ-ent environments in relationship to theexpansion/increase of HABs. To formu-late principles that explain similaritiesbetween ecosystems.

    To facilitate the development ofconceptual and numerical models ofHAB dynamics, it is imperative to rec-ognize common patterns of responseamong species. In recognition of thisconvergence and to carry out cost-ef-fective research, SEED will take advan-tage of existing model sp