OPCE-STR.vp Acta Bot. Croat. 70 (2), 269–288, 2011 CODEN: ABCRA 25 ISSN 0365–0588 Phytoplankton composition and abundance assessment in the Nador lagoon (Mediterranean coast of Morocco) FAID EL MADANI1*, ABDERRAHIM CHIAAR1, ABDELHAFID CHAFI2 1 Institut National de Recherche Halieutique – Centre Régional de Nador, 13 Boulevard Zerktouni, Nador, Morocco 2 Unité de Formation et de Recherche Techniques de Gestion de l’Environnement, Département de Biologie, Faculté des Sciences, Oujda, Morocco Abstract – We evaluated phytoplankton abundance, composition and trophic state of the Nador lagoon (Morocco) on the basis of data taken in the period November 2007 to August 2008. Sampling was performed at 11 stations (bottle samples at 0.5 m depth and horizontal plankton net tows with mesh size of 20 mm). Among seven identified phyto- plankton classes, diatoms and dinoflagellates dominated with 133 and 169 species, re- spectively. Frequent phytoplankton blooms were contributed by one to three species in the lagoon. Abundance and seasonality of phytoplankton characterized the Nador lagoon as a highly eutrophicated environment. Keywords: Mediterranean Sea, Nador lagoon, Phytoplankton, diversity, eutrophication, Introduction Taxonomic composition and size structure of phytoplankton is regulated by eutrophi- cation in coastal lagoons (PÉREZ-RUZAFA et al 2002). Eutrophication can induce massive blooms (coloured water) of phytoplankton species and the reduction in diversity. In our study, both the qualitative and quantitative aspects were considered in order to determine (a) the actual phytoplankton community structure of the Nador lagoon, (b) the spatial dis- tribution and (c) the temporal succession of the dominant species. Description of the study area The Moroccan Nador lagoon is a semi-enclosed coastal ecosystem with a surface area of about 115 km2 (Fig. 1). The lagoon is isolated from the Mediterranean Sea by a 25 km long sand bar (le Lido), crossed by one channel (Boccana). It is located in a region charac- terised by a Mediterranean climate with, often, a low and irregular rainfall – (annual mean ACTA BOT. CROAT. 70 (2), 2011 269 * Corresponding author, e-mail: elmadanifaid@hotmail.com Copyright® 2011 by Acta Botanica Croatica, the Faculty of Science, University of Zagreb. All rights reserved. U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:44 Color profile: Disabled Composite 150 lpi at 45 degrees 116–430 mm). During the year, there is a distinction between the rainy season from No- vember to March and the dry season from April to October (Fig. 2). The average depth of the lagoon is 4–7 m (Fig. 1). The depths increase from edges to the middle part of the lagoon. The salinity range is 32.7–40.2 in the confined extremity of the lagoon where the mixing of the water column is very low (BENBRAHIM 2009). The water temperature variation closely follows the temperature of the air (LAKHDAR et al. 2005) and generally ranges from 11 °C in January to 30 °C in August. Stratification of the water col- umn is weak. The Nador lagoon is one of the largest costal lagoons on the Mediterranean coast that suffer from a substantial anthropogenic wastewater overload in organic matter, nitrogen and phosphorus in addition to other various kinds of chemicals including heavy metals and 270 ACTA BOT. CROAT. 70 (2), 2011 EL MADANI F., CHIAAR A., CHAFI A. Fig. 1. The bathymetric map of Nador lagoon and its geographic position. 0 10 20 30 40 50 60 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Months 0 5 10 15 20 25 30 T e m p e ra tu re (° C ) months Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Precipitation (mm) 45.8 48.4 36.7 27.7 17.5 10.4 1.4 3 9.1 22.1 32.2 32.5 Temperature (°C) 12.2 13.1 14.3 15.7 18.2 21.65 24.3 25.1 23.1 19.3 16.15 13.6 P re c ip it a ti o n (m m ) Fig. 2. Monthly mean rainfall and temperature in Nador city, in the period 1977–1996. U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:45 Color profile: Disabled Composite 150 lpi at 45 degrees hydrocarbons (BLOUNDI 2005). This organic and inorganic complex may cause dysfunc- tions in the food web that might lead a total ecosystem imbalance, especially because of the low water exchange rate with the open sea. The turnover time of the water in the lagoon was estimated to be 80 days (HILMI 2005). However, despite the narrowness of the channel, the hydrological balance of this system shows a quasi-permanent predominance by sea water. In 1993 the channel (Boccana) was dredged and widened after a progressive accumulation of the sand that since 1987 had almost completely isolated the lagoon from the open sea; this was done in order to re-establish normal water circulation. The macrophytes recorded in the lagoon, during the present study, belong to three groups (i) Climax phanerogams Cyamodocea nodosa, and Nanozostera nolti and the Chlorobiontes Caulerpa prolifera, (ii) the opportunist algae: Ulva spp, Enteromorpha spp, Chaetomorpha linum and (iii) the drifting Rhodophyceae species Gracilaria gracilis and Alscidium corlinum. Generally, the invasive macroalgae, Caulerpa prolifera, cover most of the bottom, except the central part that is devoid of macrophytes, restricting the seaweed Cymodocea nodosa to small bands in the shallowest areas surrounding the lagoon. Diatoms are the dominant planktonic algae in the lagoon (EL MADANI et al 2001). Several watercourses drain into the lagoon but most of them become functional only during episodic flood periods (MAHJOUBI 2003). Some of them, such as Wadi Caballo, Wadi Afelioune and Wadi Akhandouk, became true open wastewater collectors that may contribute to increase the organic matter and various kinds of chemical element input. Materials and Methods Surface phytoplankton sampling was conducted, five times, roughly each two months, at 11 stations along Nador lagoon, (Fig. 3). For qualitative study, samples were collected using a standard plankton net (20 mm mesh size), in a horizontal tow for about 2 minutes at ACTA BOT. CROAT. 70 (2), 2011 271 PHYTOPLANKTON IN THE NADOR LAGOON (MAROCCO) Fig. 3. The sampling plan at stations: phytoplankton (�); temperature and salinity (�). U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:47 Color profile: Disabled Composite 150 lpi at 45 degrees each station. For quantitative plankton sampling a bottle was used. Once collected, samples were fixed immediately with neutral formalin. For identification and enumeration of phytoplankton an inverted microscope Leica DM-IRB was used. Phytoplankton identification was performed according to DODGE (1982), BALECH et al. (1984), RICARD (1987), BALECH (1988), LARSEN and MOESTRUP (1989), DELGADO and FORTUÑO (1991), HALLEGRAEFF (1991), HALLEGRAEFF et al. (1991), PAULMIER (1992, 1994), NEZAN (1996), NEZAN and PICLET (1996), TOMAS (1997), FAUST et al. (1999), MATSUOKA and FUKUYO (2000), HANSEN et al. (2001), SAR et al. (2002), KASHIMA (2002), KOENING and LIRA (2004). The salinity and temperature measurements were made in situ (20 stations) with WTW cond-197i model conductivity-salinometer (Fig. 3). Results Water temperature and salinity Salinity and temperature increase from January to August (Fig. 4). The salinity mini- mum is due to the rainfall maximum. If we consider spring the reference season, because of its moderate temperature and low rainfall, the normal salinity in the Nador lagoon is around 36.7 with small variations. The range between minimum and maximum water temperature is about 13 °C, and photoperiod seems to be the main limiting factors for the development of the phytoplankton community. Taxonomic composition A total of 311 phytoplankton species belonging to seven groups were identified during the period of study; 133 diatom species, 169 dinoflagellates, 2 cyanophyceae, 2 dyctiocho- phyceae, 2 euglenophyceae, 1 chlorophyceae, 1 coccolithophorid species and 1 raphydo- phyceae (Tab. 1). Among phytoplankton species, the most dominant were diatoms, such as: Chaetoceros spp, Pseudonitzschia spp, Nitzschia longissima, Skeletonema sp, Neocera- 272 ACTA BOT. CROAT. 70 (2), 2011 EL MADANI F., CHIAAR A., CHAFI A. 0 5 10 15 20 25 30 35 Nov. 2007 Jan. 2008 Apr. 2008 June 2008 Aug. 2008 Months T e m p e ra tu re (° C ) 33,5 34 34,5 35 35,5 36 36,5 37 37,5 38 38,5 39 S a li n it y (p su ) Temperature Salinity Fig. 4. Temporal variation of the means of the temperature and salinity of the lagoon waters dur- ing the study period. U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:47 Color profile: Disabled Composite 150 lpi at 45 degrees ACTA BOT. CROAT. 70 (2), 2011 273 PHYTOPLANKTON IN THE NADOR LAGOON (MAROCCO) Tab. 1. The spatial distribution of phytoplankton taxa (result from five samplings during 2007 and 2008). Stations 1 2 3 4 5 6 7 8 9 10 11 Dictyochophyceae 1 Hermesinum adriaticum O. Zacharias – + + + + + – + + + + 2 Dictyocha fibula Ehrenberg – – + – – – – – – + + Cyanophyceae 3 Oscillatoria sp. + + + + + + + – + – + 4 Spirulina sp. + + – – – – – – – – – Chlorophyceae 5 Scenedesmus rastro-spinosus Chodat – – – + + – – – – – – 6 Eutreptia sp. + – + + + + – + – – – 7 Euglena sp. – – – + – – – – – – – Coccolithophorids 8 Calciosolenia murrayi Gran – + + + – – – – + + + Bacillariophyceae 1 Achnanthes brevipes Agadh + + + – – – – – – – + 2 Achnanthes catenata Bily et Marvan – + + – – – – – – – + 3 Actinoptechus sp. – – – – – – – – – – + 4 Actinoptychus senarius (Ehrenberg) Ehrenberg – – – – – – – – – – + 5 Actinoptychus splendens (Shadbolt) Ralfs ex Pritchard – – – – – – – – – – + 6 Amphipleura pellucida(Kütz.) Kütz. + + + + + + + + + + + 7 Amphiprora angustata Hendey + – – – – – – – – – – 8 Amphiprora sp. – – – – – – – – – – – 9 Amphora egregia Ehrenberg – – – – – – – – – – + 10 Amphora hyalina Kützing – – – – – – – – – – + 11 Amphora laevis Gregory – – + – – – + + + – – 12 Amphora recta Grunow – – – – – – – – – – – 13 Amphora sp. + + + + – – + + – – + 14 Amphora ventricosa W. Gregory – – – – – – – – – – + 15 Asterionella japonica Cleve et Moller + + – + – – – – – – + 16 Auliscus sculptus (W. Smith) Ralfs ex Pritchard – – – – – – – – – – + 17 Auliscus sp. – – – – – – – – – – + 18 Bacillaria paxillifera (Müller) Hendey + + + + + + + + + + + 19 Biddulphia edwardsii Febiger ex Grunow – – – – – – – – – + – 20 Biddulphia pulchella S.F. Gray – – – – – – – – – – + 21 Biddulphia rhombus (Ehrenberg) W. Smith – – + – – – – – – – – 22 Biddulphia sp. – – – – – – – – – – + 23 Biddulphia tuomeyi (Bailey) Roper – – – – – – – – – – + U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:47 Color profile: Disabled Composite 150 lpi at 45 degrees 274 ACTA BOT. CROAT. 70 (2), 2011 EL MADANI F., CHIAAR A., CHAFI A. Stations 1 2 3 4 5 6 7 8 9 10 11 24 Campylodiscus decorus de Brébisson – – – – – – – – – – + 25 Cerataulina pelagica (Cleve) Hendey + + + – + – + + + + + 26 Chaetoceros affinis var. willei (Gran) Hustedt – – + – – – – + – – – 27 Chaetoceros brevis Shütt + – – – – – – – – – – 28 Chaetoceros curvisetus Cleve + + + + – – – – – + – 29 Chaetoceros danicus Cleve – – + – – + – + – – – 30 Chaetoceros decipiens Cleve – + + + + + + + + + + 31 Chaetoceros didymus Ehrenberg – + – – – – – – – – – 32 Chaetoceros laciniosus Schütt – – – – – – – + – – – 33 Chaetoceros laevis Leuduger–Fortmorel – + – – – – – – – – – 34 Chaetoceros lauderi Ralfs – – – – – + – – – – – 35 Chaetoceros mitra (J.W. Bailey) Cleve + + + + – + + + + + + 36 Chaetoceros peruvianus Brightwell – + + + + – – + + + + 37 Chaetoceros pseudocurvisetus Mangin – + – – – – – – – – – 38 Chaetoceros simplex Ostenfeld – – – + – – – – – – – 39 Chaetoceros spp. + + + + + + + + + + + 40 Chaetoceros teres Cleve – + – + – + + – – – + 41 Chrysanthemodiscus floriatus Mann – – – – – – – – – – + 42 Climaconeis sp. – – – – – – + – – – – 43 Cocconeis scutellum Ehrenberg – + – – – + – + – – + 44 Cocconeis sp. + – + – – – – – + – + 45 Corethron criophilum Castracane – + – – – – – – – – – 46 Coscinodiscus sp. – – + – – – – – – – + 47 Dactyliosolen fragilissimus (Bergon) G. R. Hasle – – – + – – – – – + – 48 Diatoma mesodon (Ehrenberg) Kützing – – – – – – – – – – + 49 Diploneis chersonensis (Grunow) Cleve – – – – – – – – – – + 50 Diploneis sp. – – – – – – – – + – – 51 Ditylum brightwellii (T. West) Grunow + – + – – – – – – + – 52 Entomoneis alata (Ehrenberg) Ehrenberg + – + – + + + – + – – 53 Entomoneis sp. + + – – – – – – – – – 54 Epithemia turgida (Ehrenberg) Kütz – – – – – – – – – – + 55 Goniothecium odontella Ehrenberg – – – – – – – – – – + 56 Grammatophora angulosa Ehrenberg – – – – – – – – – – + 57 Grammatophora marina (Lyngbye) Kützing – + + – – – – – – – – 58 Guinardia delicatula (Cleve) Hasle – – – – – + + – – – + 59 Guinardia flaccida (Castracane) H. Peragallo + – – – – – – – – – + 60 Guinardia striata (Stoltherfoth) Hasle – + + – + + + + + + + Tab. 1. – continued U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 26. rujan 2011 14:34:20 Color profile: Disabled Composite 150 lpi at 45 degrees ACTA BOT. CROAT. 70 (2), 2011 275 PHYTOPLANKTON IN THE NADOR LAGOON (MAROCCO) Stations 1 2 3 4 5 6 7 8 9 10 11 61 Gyrosigma fasciola (Ehrenberg) J.W.Griffith et Henfrey + + – + + – + – – + – 62 Gyrosigma scalproide (Rabenhorst) Cleve – + – + – – – – + – + 63 Gyrosigma sp. – – – + – + – – – – – 64 Gyrosigma wansbeckii (Donkin) Cleve – – – – + – – – – – – 65 Hantzschia amphioxus (Ehrenberg) Grunow – – – – – – – – – – + 66 Haslea wawrikae (Husedt) Simonsen – + + + – + – – – – + 67 Hemialus hauckii Grunow ex Van Heurck + + + + + + + – + + + 68 Hemiaulus sinensis Greville – – – – + – – – – – – 69 Lauderia annulata Cleve – – – – – – – – – – + 70 Lauderia sp. – – – – – – – – + – – 71 Leptocylindrus danicus Cleve – + + + – + – + + + + 72 Leptocylindrus minimus Gran – + + + + + + + + + + 73 Licmophora flabellata (Greville) Agardh + + + + + + + + + + + 74 Licmophora gracilis (Ehrenberg) Grunow + + + + + + – – – + + 75 Licmophora sp. + + – – – – – – – + + 76 Lioloma pacificum (Cupp) Hasle – – – + – + – – – + – 77 Lioloma sp. – + – – – – – – – – – 78 Melosira nummuloides C.A. Agardh – + – – – – – – – – – 79 Melosira sp. – – – – – – – – – + + 80 Meuniera membranacea (Cleve) P.C. Silva in Hasle et Syvertsen + – – – – – – – – – + 81 Navicula cf. carinifera Grun. Grunow in Schmidt – + – – – – – – – – – 82 Navicula forcipata Greville – – – – – – – – – – + 83 Navicula hasta Pantocsek – – – – – – – – – – + 84 Navicula hennedyi W.Smith – – – – – – – – – – + 85 Navicula humerosa Brébisson ex W. Smith – – – – – – – – – – + 86 Navicula lanceolata (C. Agardh) Kützing – – – – – – – – – – + 87 Navicula menaiana Hendey – – – – – – – – – – + 88 Navicula smithii Navicula smithii (Agardh) Van Heurck – – – – – – – – – – + 89 Navicula spp. – + + – + + – – + – + 90 Navicula tuscula (Ehrenberg) Grunow – + – – – – – – – – – 91 Cylindrotheca closterium (Ehrenberg) Reimann et J.C.Lewin Kingston – + + + + + + – + + + 92 Nitzschia levidensis (W. Smith) Grunow in Cleve et Grunow – – – – – – – – – – + 93 Nitzschia longissima (Brébisson) Ralfs + + + + + + + + + + + Tab. 1. – continued U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:47 Color profile: Disabled Composite 150 lpi at 45 degrees 276 ACTA BOT. CROAT. 70 (2), 2011 EL MADANI F., CHIAAR A., CHAFI A. Stations 1 2 3 4 5 6 7 8 9 10 11 94 Nitzschia panduriformis W. Gregory – – – – – – – – – – + 95 Nitzschia sigma (Kützing) W. Smith – + – – – + – – – – + 96 Nitzschia sp. – + + + + + + + + + + 97 Nitzschia ventricosa Kitton + + – – + + + + + + + 98 Oestrupia musca (Gregory) Hustedt – – – – – – – – – – + 99 Plagiotropis lepidoptera (Greg.) Reimer Navarro – – – – – – + – – – – 100 Planctoniella sol (Wallich) Schutt – – – – – – – – – – + 101 Pleurosigma elangatum W. Smith + + + – + + + + + + + 102 Pleurosigma itium Ricard – + + + + + + – + + + 103 Pleurosigma spp. + – + + – – – – – – + 104 Podocystis adriatica (Kützing) Ralfs – + – – – – – – – – + 105 Proboscia alata (Brightwell) Sundström – – – – – – – – – – + 106 Pseudoguinardia recta von Stosch – – – – – – – – – + + 107 Pseudo-nitzschia spp. + + + + + + + + + + + 108 Rhizosolenia alata Brightwell – – – – – – – – – – + 109 Rgizosolena setigera Brightwell – + – + + – – + – + – 110 Rhizosolenea sp. – – – + – – – – – – – 111 Rhizosolenia alata forma indica (H. Peragallo) Gran – – – – – – – – + – + 112 Rhizosolenia setigera Brightwell + + + + + + – + + + + 113 Rhizosolenia sp. – – – – – – – – – – + 114 Rhizosolenia styliformis Brightwell – – – – + + – – – + + 115 Rhoicosigma sp. – – – – – – – – – – + 116 Skeletonema sp. – + + + + + + + + + + 117 Stauroneis amphioxys Gregory – – – – – – – – – – + 118 Stenopterobia intermedia (Lewis) Brébisson ex Van Heurck – – – – – – – – – – + 119 Helicotheca tamesis Ricard – – – + – – – – – – – 120 Striatella unipunctata (Lyngbye) C. Agardh + + + + – – + – – – + 121 Surirella amoricana H. Peragallo – – – – – – – – – – + 122 Surirella fastuosa Ehrenberg – – – + + + – – – + + 123 Surirella gemma (Ehrenberg) Kützing – + + + – + + – – – – 124 Surirella sp. – – – – – – – – – – + 125 Synedra sp. + – – – – – – – – – – 126 Thalassionema nitzschioides (Grunow) Mereschkowsky + + + + + + + + + + + 127 Thalassiosira hyalina (Grunow) Gran – – – – – – – – – – + 128 Thalassiosira sp. + + – – + – – – – + + Tab. 1. – continued U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:47 Color profile: Disabled Composite 150 lpi at 45 degrees ACTA BOT. CROAT. 70 (2), 2011 277 PHYTOPLANKTON IN THE NADOR LAGOON (MAROCCO) Stations 1 2 3 4 5 6 7 8 9 10 11 129 Thalassiothrix froenfeldeii Grunow + + + – + – + – + – + 130 Thalassiothrix spp. + + + + + + + + + + + 131 Toxonidea sp. – – – – – – – – – – + 132 Triceratium alternans J. W. Bailey – – – – – – – – + – + 133 Trichotoxon reinboldii (Van Heurck) Reid et Round – + – – – – – – – + – Dinoflagellates 1 Achradina pulchra Lohmann + + – – – + + – – – – 2 Alexandrium catenella (Whedon et Kofoid) Balech – – + + – – – – – – + 3 Alexandrium margalefi Balech – – – – – – – – – + + 4 Alexandrium minutum Halim + + + + + + + + + + + 5 Alexandrium pseudogonyaulax (Biecheler) Horiguchi ex Yuki et Fukuyo – + + – – + – + + + + 6 Alexandrium sp. – – – – – – – – + – + 7 Alexandrium tamarense (Lebour) E.Balech – – – – – – + – – – – 8 Amphidinium sp. – – – + + – – – – – – 9 Amphidoma caudata Halldal + + + + + + + + + + + 10 Amylax sp. – – – + – – – – – – – 11 Archaeperidinium sp. – – – – – – – – – – + 12 Coolia monotis Meunier + + + – – – + + – + + 13 Cyst Alexandrium minutum – – – + + + – + + + – 14 Cyst of dinoflagellates + + + – – + + + + + + 15 Dinophysis caudata Saville–Kent – + – – – – + + + + + 16 Dinophysis contracta (Kofoid et Skogsberg) Balech – – – – – – – – – – + 17 Dinophysis diegensis Kofoid – – – – – – – – – – + 18 Dinophysis exigua Kofoid and Skogsberg – – + – – – – – + + + 19 Dinophysis rapa (Stein) Balech – – – – – – – – – – + 20 Dinophysis rotundata Claparède et Lachmann – – – – – – – – – – + 21 Dinophysis sacculus Stein + + + + + + + + + + + 22 Dinophysis sp. – – – – – – – – – – + 23 Diplopelta asymetrica (Mangin) Lindermann – – – – + – – + – – – 24 Diplopelta steinii (T. H. Abé) E. Balech – – – – – – – – – – + 25 Diplopeltopsis minor Pavillard – + – – – – – – – – + 26 Diplopeltopsis sp. – + – – – – – – – – – 27 Diplopsalis sp. + + + – + + + + + + + 28 Diplopsalopsis bomba (Stein ex Jörgensen) J. D. Dodge et S. Toriumi – – – – – – – – + – – Tab. 1. – continued U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 26. rujan 2011 14:05:26 Color profile: Disabled Composite 150 lpi at 45 degrees 278 ACTA BOT. CROAT. 70 (2), 2011 EL MADANI F., CHIAAR A., CHAFI A. Stations 1 2 3 4 5 6 7 8 9 10 11 29 Diplopsalopsis sp. – – – – – – – – – + – 30 Ensciculifera sp. + + + + – + + + + – + 31 Ensiculifera angulata E. Balech – – – – – – – – – + – 32 Ensiculifera angulata E. Balech – – – – – – – – – – + 33 Gambierdiscus toxicus Adachi and Fukuyo + – – – – – – – – – – 34 Goniodoma polyedricum (Pouchet) Jörgensen – – + – – – – – – + + 35 Gonyaulax dicantha (Meunier) Schiller – – + + + + + + + – + 36 Gonyaulax digitale (Pouchet) Kofoid + – – + – + + + – + + 37 Gonyaulax grindleyi Reinecke – – – – – – – + – – + 38 Gonyaulax polygramma Stein – – – – – + – – + + + 39 Gonyaulax sousae Balech + + + + + + + + + + + 40 Gonyaulax spinifera (Claparède et Lachmann) Diesing + + + + + + + + + + + 41 Gonyaulax striata Mangin – – – – – – – – – – + 42 Gonyaulax turbynei Murray et Whitting – – – – – – – – – + + 43 Gonyaulax unicornis Lebour + + – + + – + + + – + 44 Gonyaulax veriore Sournia – – – – – – – + + – – 45 Gotoius mutsuensis Abé – – – – – – – – – + – 46 Gymnodinium catenatum Graham – + – + – – – – – – – 47 Gymnodinium sanguineum K. Hirasaka + + + + + + + + + + + 48 Gymnodinium sp. – + – – – – + + – + + 49 Gyrodinium sp. – – + + – – – + – – + 50 Gyrodinium spirale (Bergh) Kofoid et Swezy – + + + – + + + + + – 51 Heterocapsa circularisquama Horiguchi – – – – – – – – – + – 52 Heterocapsa niei (Loeblich) Morrill et Loeblich III – – – + – – – + + + – 53 Heterocapsa rotundata (Lohmann) G. Hansen – – – – – – – + + + – 54 Heterocapsa triquetra (Ehrenberg) F. Stein – – + – – – – – – – – 55 Katodinium sp. – + – – – + + – – + + 56 Lingulodinium polyedrum (Stein) Dodge + + + + + + + + + + + 57 Neoceratium azoricum (Cleve) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 58 Neoceratium candelabrum (Ehrenberg) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 59 Neoceratium contrarium (Gourret) F. Gómez, D. Moreira et P. López-García – + – – – – – – – + + 60 Neoceratium declinatum f. declinatum (Sournia) F. Gómez, D. Moreira et P. López-García – – – – – – – – – + – Tab. 1. – continued U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 26. rujan 2011 14:05:26 Color profile: Disabled Composite 150 lpi at 45 degrees ACTA BOT. CROAT. 70 (2), 2011 279 PHYTOPLANKTON IN THE NADOR LAGOON (MAROCCO) Stations 1 2 3 4 5 6 7 8 9 10 11 61 Neoceratium declinatum f. majus (Jörgensen) F. Gómez, D. Moreira et P. López-García – – – – – – – – – + – 62 Neoceratium deflexum (Kofoid) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 63 Neoceratium extensum (Gourret) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 64 Neoceratium furca (Ehrenberg) F. Gómez, D. Moreira et P. López-García + + + + + + + + + + + 65 Neoceratium fusus (Ehrenberg) F. Gómez, D. Moreira et P. López-García – + + + – – – – + + + 66 Neoceratium karstenii (Pavillard) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 67 Neoceratium lineatum (Ehrenberg) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 68 Neoceratium longipes (Bailey) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 69 Neoceratium macroceros (Ehrenberg) F. Gómez, D. Moreira et P. López-García – + – – – – – – – + – 70 Neoceratium massiliens (Gourret) F. Gómez, D. Moreira et P. López-García – – – – – – – – – + + 71 Neoceratium massiliens armatum (Karsten) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 72 Neoceratium pentagonum var. tenerum (Jörgensen) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 73 Neoceratium teres (Kofoid) F. Gómez, D. Moreira et P. López-García – – – – – – – – + – – 74 Neoceratium trichoceros (Ehrenberg) F. Gómez, D. Moreira et P. López-García – + + – – – – + – + + 75 Neoceratium tripos (O. F. Müller) F. Gómez, D. Moreira et P. López-García – – + – – – – – + – – 76 Neoceratium tripos f. tripodoides (Jörgensen) F. Gómez, D. Moreira et P. López-García – – – – – – – – – – + 77 Noctiluca scintillans (Macartney) Kofoid et Swezy – + + + + + – + + + + 78 Oblea baculifera Balech ex Loeblich Jr. et Loeblich III + – + + + + + + + + + 79 Ornithocercus magnificus Stein – – – – – – – – – – + 80 Ostreopsis ovata Fukuyo – – + – – – – – – – + 81 Palaeophalacroma unicinctum Schiller – – – – – – – – – – + 82 Pentapharsodinium sp. – – + – – – – – – + – Tab. 1. – continued U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 26. rujan 2011 14:05:26 Color profile: Disabled Composite 150 lpi at 45 degrees 280 ACTA BOT. CROAT. 70 (2), 2011 EL MADANI F., CHIAAR A., CHAFI A. Stations 1 2 3 4 5 6 7 8 9 10 11 83 Peridiniella sp. + + + + – – – – – – – 84 Periperidinium sp. – – + – + + – – – + – 85 Podolampas palmipes Stein – – – – – – – – – + – 86 Polykrikos schwarzii Bütschli – + – – + + + + + + + 87 Prorocentrum balticum (Lohmann, 1908) Loeblich – – – – – – – – – – + 88 Prorocentrum compressum (Bailey) Abé ex Dodge – – – – – – – – – – + 89 Prorocentrum lima (Ehrenberg) Dodge + – – – – – – – – + + 90 Prorocentrum mexicanum Tafall + + + + + + + + – + + 91 Prorocentrum micans Ehrenberg + + + + + + + + + + + 92 Prorocentrum minimum (Pavillard) Schiller + + – + + + – + + + – 93 Prorocentrum ruetzlerianum Faust + – – – – – – – – – – 94 Prorocentrum sigmoide Bohm + + – + + + + – + + – 95 Prorocentrum sp. – – – – – – – – + – + 96 Prorocentrum triestinum Schiller + + + + + + + + – + + 97 Protoceratium reticulatum (Claparède et Lachmann) Butschli – – – – – – – + – – + 98 Protoceratium sp. – – – – – – – – – + + 99 Protoperidinium acanthophorum (Balech) Balech + – – – – – – – – – – 100 Protoperidinium bipes (Paulsen) Balech + + + + + + + + + + + 101 Protoperidinium bispinum (Schiller)Balech + + + + + + + + + + + 102 Protoperidinium brevipes (Paulsen) Balech + + – – + + – – + – + 103 Protoperidinium capurroi (Balech) Balech + – + – – – – – – – – 104 Protoperidinium cf. avellana (Meunier) Balech + – – – – – – – – – – 105 Protoperidinium cf. capurroi subpellucidum (E. Balech) E. Balech – – – – – – – – – – + 106 Protoperidinium cf. nanum (Balech) Balech – – – – – – – – – – + 107 Protoperidinium cf. obtusum (Karsten) Parke et Dodge – – – – – – – – – + – 108 Protoperidinium claudicans (Paulsen) Balech – – – – – – – – – + + 109 Protoperidinium conicoides (Paulsen) Balech + + – – – – + – + + + 110 Protoperidinium conicum (Gran) Balech – + – + – – – + + + + 111 Protoperidinium conicum (Gran) Balech avr. conicum in Balech – – + + – – – – – – – 112 Protoperidinium conicum (Gran) Balech var. concavum Matzenauer – – – – – – – – – – + 113 Protoperidinium cruciferum (Balech) Balech – – – – – – – – + – – 114 Protoperidinium curtipes (Jörgensen) Balech – – – – – – – + + – – Tab. 1. – continued U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:48 Color profile: Disabled Composite 150 lpi at 45 degrees ACTA BOT. CROAT. 70 (2), 2011 281 PHYTOPLANKTON IN THE NADOR LAGOON (MAROCCO) Stations 1 2 3 4 5 6 7 8 9 10 11 115 Protoperidinium decipiens (Jörgensen) Parke et Dodge (Jörgensen) Parke et Dodge – – + – – – – – – – – 116 Protoperidinium depressum (Bailey) Balech – + – – – – – – – – + 117 Protoperidinium diabolus (Karsten) Balech – + + + + + + + + + + 118 Protoperidinium divaricatum (Meunier) Balech – – – – – – + – + – – 119 Protoperidinium divergens (Ehrenberg) Balech (Ehrenberg) Balech + + – – – + + + + + + 120 Protoperidinium excentricum (Paulsen) Balech – – – – – – – – – – + 121 Protoperidinium fartum Balech – – – – – – – – – – + 122 Protoperidinium gibbosum (Matzenauer) Balech – – – – – + – – – – – 123 Protoperidinium granii (Ostenfield) Balech (Ostenfield) Balech – – – – – + – – – – – 124 Protoperidinium hirobis Abè + + + + + + – + + + + 125 Protoperidinium hirobis Abè – – – – – – – – – + – 126 Protoperidinium incognitum (Balech) Balech – – – – – – – + – – – 127 Protoperidinium latispinum (Mangin) Balech – – – – – – – – – – + 128 Protoperidinium leonis (Pavillard) Balech – – – – – – + + + – + 129 Protoperidinium mastophorum (Balech) Balech – – + + – – – + – + + 130 Protoperidinium metananum (Balech) Balech – – + + – – – + – – – 131 Protoperidinium minutum (Kofoid) Loeblich III – – – – + – – – – – + 132 Protoperidinium mite (Pavillard) Balech – + + – + – – + – + + 133 Protoperidinium nanum (Balech) Balech – – + – – – – – – – – 134 Protoperidinium nudum (Meunier) Balech – – – – – – – + – + – 135 Protoperidinium oblongum (Aurivillius) Parke et Dodge + + + + + + + + + + + 136 Protoperidinium obtusum (Karsten) Parke et Dodge – – – – – – – + + – – 137 Protoperidinium ovatum subsp. asymmetricum Pouchet + + + – – – – – + – – 138 Protoperidinium oviforme (Dangeard) Balech – + – – – – – – – – + 139 Protoperidinium ovum (Schiller) Balech – – – – – – – + – – + 140 Protoperidinium pallidum (Ostenfeld) Balech – – + – – – – – – – – 141 Protoperidinium parapyriforme (Hermosilla) Balech – – – + + – – – – + + 142 Protoperidinium parcum (Balech) Balech – – – – – – – – + – – 143 Protoperidinium parviventer Balech – – – – – – – – + – – 144 Protoperidinium paulseni Pavillard – – – – – – – – + – – 145 Protoperidinium punctulatum (Paulsen) Balech + + + + + + + + + + + Tab. 1. – continued U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:48 Color profile: Disabled Composite 150 lpi at 45 degrees tium furca, Gonyaulax souseae, Alexandrium minutum, Scrippsiella trochoidea, Prorocen- trum triestinum and Achradina pulchra. A maximum of 201 taxa were observed at station 11, the minimum of 72 species at station 7 (Fig. 5). Abundance The maximum phytoplankton abundance was found in August 2008 (Fig. 6), due to the bloom of Nitzschia longissima (1.7 ´ 107 cells L–1 at station 1, located in the N-W Beninsar area, and the bloom of Skeletonema (7.4 ´ 106 cells L–1) observed at station 4. The mini- mum abundance was recorded in November 2007. 282 ACTA BOT. CROAT. 70 (2), 2011 EL MADANI F., CHIAAR A., CHAFI A. Stations 1 2 3 4 5 6 7 8 9 10 11 146 Protoperidinium pyriforme var. pyriforme (Paulsen) Balech – – + – + – – – – – + 147 Protoperidinium quarnerense (Schröder) Balech – – – – – – – – – – + 148 Protoperidinium quinquecorne (Abé) Balech – – – + – – – – – – – 149 Protoperidinium simulum (Paulsen) Balech – – – – – – – + – – – 150 Protoperidinium sp. + + + – – – – + – + + 151 Protoperidinium sphaeroideum (Mangin) Balech – – – – – – – – + – + 152 Protoperidinium spinulosum Schiller – – + + + + + – + – + 153 Protoperidinium steidingerae Balech – – – – – – – – – – – 154 Protoperidinium steinii (Jørgensen) Balech + – – – – – – – – + + 155 Protoperidinium subcrassipes E. Balech – – – – – – – – – – + 156 Protoperidinium subpyriforme (Dangeard) Balech – – – – – – + – – – – 157 Protoperidinium subsphaericum (Broch) Balech + – – – – – – – – – – 158 Protoperidinium thorianum (Paulsen) Balech + – – + – – – – – – – 159 Protoperidinium ventricum (Abé) Balech – – – + – – – – – – – 160 Protoperidinium vulgare Balech – – + – – – – – – – – 161 Pyrocystis noctiluca Murray ex Haeckel Murray ex Haeckel – – – + – – – – – + – 162 Pyrophacus horologicum Stein + + + + + + + + + + + 163 Pyrophacus sp. – – – – – – – – + – – 164 Pyrophacus steinii (Schiller) Wall et Dale – – – – – – – – – – + 165 Scrippsiella precaria Montressor et Zingone – – – – – – – + – – – 166 Scrippsiella spinifera G. Honsell et M. Cabrini – + + + + + – + + + + 167 Scrippsiella sweeneyae Balech ex Loeblich III + – + + – + – + + + + 168 Scrippsiella trochoidea (Stein) Loeblich III + + + + + + + + + + + 169 Spirilax jollifei (Murray et Whitting) Kofoid + + + – – – – + – – – Tab. 1. – continued U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:48 Color profile: Disabled Composite 150 lpi at 45 degrees The abundances in January and June differ due to the bloom of Chaetoceros observed in January at station 10, with abundance exceeding 2 ´ 106 cells L–1. November 2007 and January 2008: The community was dominated by the diatom Chaetoceros which contributed in 96.14% and 99.06% respectively in November and January. In November, the maximum phytoplankton abundance was recorded at Station 2, with 4.4 ´ 104 cells L–1 (Fig. 7). The dominance of Chaetoceros was observed all over of the la- goon with the exception of stations 5 and 6 where Neoceratium furca dominated. ACTA BOT. CROAT. 70 (2), 2011 283 PHYTOPLANKTON IN THE NADOR LAGOON (MAROCCO) Fig. 5. Spatial distribution of the phytoplankton taxa numbers. 0 40 80 120 160 200 Nov. 2007 Jan. 2008 Apr. 2008 Jun. 2008 Aug. 2008 Samling period G e o m e tr ic m e a n o f p h y to p la n k to n a b u n d a n c e (c e ll s m L ) – 1 Fig. 6. Temporal variation of the geometric mean of phytoplanktonic abundance of the 11 stations. U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:49 Color profile: Disabled Composite 150 lpi at 45 degrees In January 2008, beside the dominance of Chaetoceros, dinoflagellates such as Gon- yaulax souseae, Alexandrium minutum, Scrippsiella trochoidea and Prorocentrum trie- stinum co-dominated at stations 1 and 2. April 2008: High abundances were recorded at the station 10, with about 9.5 ´ 105 cells L–1 of Pseudo-nitzschia, which contributed 72.19% of the community abundance. Jun 2008: The maximum abundance was recorded at the station 1, with 1.7 ´ 107 cells L–1 which was mostly contributed by Nitzschia longissima (99.9% of the community abun- dance). August 2008: The maximum abundance was recorded at station 5, with 8.5 ´ 105 cells L–1 of unidentified rounded cells, 17 to 20 mm in diameter (dinoflagellates or rhaphidophycean flagellatres), contributing 95.7% of the community abundance. We also found abundant 284 ACTA BOT. CROAT. 70 (2), 2011 EL MADANI F., CHIAAR A., CHAFI A. June 2008 0 3000 6000 9000 12000 15000 18000 1 4 6 8 10 3 2 7 5 11 9 January 2008 0 500 1000 1500 2000 2500 10 4 11 5 8 6 3 7 2 1 9 November 2007 0 5 10 15 20 25 30 35 40 45 50 2 8 10 4 1 3 5 11 7 9 6 A b u n d a n c e (c e ll s m L ) – 1 April 2008 0 200 400 600 800 1000 10 8 9 7 1 4 11 5 6 3 2 Stations A b u n d a n c e (c e ll s m L ) – 1 August 2008 0 200 400 600 800 1000 5 8 3 9 10 1 2 7 11 6 4 Stations A b u n d a n c e (c e ll s m L ) – 1 Fig. 7. Spatial variation of phytoplankton abundance during the investigated period. U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 9. rujan 2011 13:04:49 Color profile: Disabled Composite 150 lpi at 45 degrees dinoflagellate Achradina pulchra (5.9 ´ 105 cells L–1) at station 8, and Nitzschia longissima (4 ´ 105 cells L–1) at station 3. The dominant species (with abundance greater than 104 cells L–1) for each sampling cruise are summarized in table 2. Generally, diatoms dominated the phytoplankton com- munity, with the occasional dominance of unidentified flagellates and dinoflagellates in August 2008. Discussion In the present study, diatoms were generally dominant. The maximum number of taxa was observed at station 11, situated in Boccana channel, with a greater exchange of water between the lagoon and the open sea. The minimum number of taxa was found at station 7 located in the confined Kariat Arekman area as found in the period 1982–1993 (LEFEBVRE et al 1996). The difference in diversity between these two areas shows that more than half of the phytoplankton population comes from the open sea. The highly eutrophic conditions in the lagoon cannot maintain populations. In addition, GILABERT (2001a) explains the low diversity in the lagoon by strong physical perturbations. Anyway, more than 114 species are adapted to the lagoon’s ecological conditions. About 44 phytoplankton species are common in most sampling stations (those found in at least 6 sampling stations). The number of diatoms and dinoflagellates identified in different parts of the Mediter- ranean Sea mostly varies between 107 and 183 of diatoms, and 107 to 205 dinoflagellates (VILI^I] et al. 2002). In the Nador lagoon, we found 133 diatoms and 169 dinoflagellates. ACTA BOT. CROAT. 70 (2), 2011 285 PHYTOPLANKTON IN THE NADOR LAGOON (MAROCCO) Tab. 2. Seasonality of dominant and accompanying species in the Nador Lagoon. sampling campaign Dominants species Accompanying species (Density > 104) November 2007 Chaetoceros spp. Neoceratium furca (Ehrenberg) F. Gómez, D. Moreira et P. López-García, Pseudo-nitzschia spp. January 2008 Chaetoceros spp. Prorocentrum triestinum Schiller Small dinoflagellates (*) Skeletonema sp. Pseudo-nitzschia spp. Divers Bacillariophyceae pennates Nitzschia longissima (Brébisson) Ralfs April 2008 Pseudonitzschia spp. Leptocylindrus minimus Gran Thalassionema nitzschioides (Grunow) Mereschkowsky Nitzscha longissima, (Brébisson) Ralfs Small dinoflagellates (*) Chaetoceros spp. Eutreptia sp. Prorocentrum triestinum Schiller (*): Alexandrium minutum, Gonyaulax verrior, G. sousea, G. dicantha Scrippsiella spp, Protoperidinium bipes, P. quinquecorne, P. hirobis, and others similar forms. U:\ACTA BOTANICA\Acta-Botan 2-11\El Madani.vp 26. rujan 2011 14:07:11 Color profile: Disabled Composite 150 lpi at 45 degrees In the Nador lagoon we recorded a high abundance of Nitzschia longissima (1.7 ´ 107 cells L–1) in June at station 1. This station is situated in the confined area in the north-west part of the Mar Chica that receives wastewater from Beninsar City. An increasing abun- dance of phytoplankton, especially diatoms to 5 ´ 106 cells L–1, usually reveals an area of anthropogenic influence (VILI^I] 1989). Nador lagoon is slightly eutrophicated in October, with an tendency to increase with the approach of summer, due to the increasing temperature, light intensity and input of nu- trients into the lagoon (fig. 4, 7). The eutrophication of the lagoon is manifested by the re- duction of the water clarity, which is the direct result of the phytoplankton blooms, corre- sponding to the diatoms Chaetoceros, Pseudo-nitzschia, Nitzschia longissima etc. In summer, chlorophyll concentrations range from below 5 mg L–1 to 20 mg L–1, and oxygen decrease to anoxic conditions at stations 1 and 4. Strong eutrophic conditions were ob- served in the last decade. The blooms cause a green, brown or yellowish-brown discolor- ation of water. The bloom degradation results in increasing oxygen demand and degrad- ation of water quality. Seasonal variations of primary production are the result of external physical chemical environmental variables and the shallowness of the lagoon (GILABERT 2001a, b). During several years, we have observed that summer phytoplankton blooms are accom- panied by appearance of abundant jellyfish Rhyzostoma pulmo. Occurrences were reported in the Mar Menor, where these organisms may play an important role in controlling eutrophication by feeding on diatoms and zooplankton (PÉREZ-RUZAFA et al. (2002). The qualitative and quantitative results lead us to conclude that, in general, the Nador lagoon seem to be highly affected by eutrophication. A new channel (300 m wide) is going to be opened to increase the lagoon water exchange with the open sea, with an expected re- duction of the residence time of water in the lagoon. This action is expected to have a great impact on the water quality by reducing the present eutrophication level, which will be ac- companied by the modification of current phytoplankton population structure. Acknowledgements The authors thank Saida MOTIA and Najib EL OUAMARI for their comments on the first version, and Professor Amany Ismael for the review of the last version of the paper; Siham EL MADANI for language verification. 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