Figure 1
Location of the study sites
Figure 2
Monthly variations in: A) average temperature and B) salinity at different studied sites
Figure 3
Chemical and biological parameters obtained from different sites during the study period: A) nitrate, B) nitrite, C) ammonia, D) phosphate, E) silicate and F) chlorophyll a
Figure 4
Variations in densities of total phytoplankton and different groups (A, C, E) along with the percentage contribution of each group to the total abundance (B, D, F) observed at site 1 (A, B), site 2 (C, D) and site 3 (E, F)
Figure 5
Dendrogram based on the Bray–Curtis similarity index revealing the pattern of phytoplankton abundance and distribution during the study period at three sites: A) site 1, B) site 2 and C) site 3
Table 1
Values of Pearson's correlation coefficient (r) obtained for different environmental parameters observed during the study period (S – salinity, T – temperature, NO3− – nitrate, NO2− – nitrite, NH4+ – ammonia, PO43− – phosphate, SiO44− – silicate, Chl a – chlorophyll a and TPD – total phytoplankton abundance)
Table 2
One-Way ANOVA obtained for different environmental parameters observed during the study period
| Parameters | Between sites | Between months | ||
|---|---|---|---|---|
| F | Sig. | F | Sig. | |
| Temperature | 0.011 | 0.999 | 728.13 | 0.001 |
| Salinity | 4.552 | 0.018 | 4.336 | 0.001 |
| Nitrate | 3.214 | 0.053 | 1.155 | 0.366 |
| Nitrite | 4.531 | 0.018 | 0.68 | 0.743 |
| Ammonia | 4.205 | 0.024 | 1.591 | 0.165 |
| Phosphate | 0.063 | 0.939 | 10.413 | 0.000 |
| Silicate | 18.508 | 0.000 | 0.573 | 0.831 |
| Chlorophyll a | 0.585 | 0.563 | 1.91 | 0.090 |
| Total phytoplankton density | 0.291 | 0.75 | 1.853 | 0.1 |
Table 3
Biodiversity indices obtained for phytoplankton distribution at three sites, where S is the total number of species, J’ is Pielou's evenness index and H’ is the Shannon–Wiener diversity index
| Month | Site 1 | Site 2 | Site 3 | ||||||
|---|---|---|---|---|---|---|---|---|---|
| S | J′ | H′ | S | J′ | H′ | S | J′ | H′ | |
| January | 59 | 0.998 | 4.07 | 72 | 0.998 | 4.27 | 32 | 0.998 | 3.46 |
| February | 29 | 0.998 | 3.36 | 79 | 0.999 | 4.37 | 23 | 0.999 | 3.13 |
| March | 35 | 0.999 | 3.55 | 40 | 0.999 | 3.69 | 32 | 0.999 | 3.46 |
| April | 39 | 0.999 | 3.66 | 38 | 0.999 | 3.64 | 19 | 0.999 | 2.94 |
| May | 63 | 0.998 | 4.14 | 31 | 0.998 | 3.43 | 20 | 0.998 | 2.99 |
| June | 44 | 0.998 | 3.78 | 30 | 0.996 | 3.39 | 30 | 0.998 | 3.39 |
| July | 53 | 0.998 | 3.96 | 57 | 0.998 | 4.04 | 27 | 0.998 | 3.29 |
| August | 44 | 1.000 | 3.78 | 33 | 0.999 | 3.49 | 26 | 1.000 | 3.26 |
| September | 33 | 0.999 | 3.49 | 36 | 1.000 | 3.58 | 17 | 0.999 | 2.83 |
| October | 43 | 0.997 | 3.75 | 50 | 0.999 | 3.91 | 38 | 0.999 | 3.64 |
| November | 54 | 0.998 | 3.98 | 61 | 0.999 | 4.11 | 55 | 0.999 | 4.00 |
| December | 32 | 1.000 | 3.46 | 29 | 0.999 | 3.36 | 24 | 0.997 | 3.17 |
Supplementary material 1
List of different phytoplankton species observed at the three sites during the study period. [– indicates the absence, + indicates the presence of a given species (< 1 × 103 individuals m−3), ++ indicates moderate cell abundance (10 to 100 × 103 individuals m−3) and +++ indicates high cell abundance (> 900 × 103 individuals m−3)].
| Site 1 | Site 2 | Site 3 | |
|---|---|---|---|
| Bacillariophyceae Centric diatoms | |||
| Bacteriastrum hyalinum Lauder, 1864 | − | − | + |
| Bellerochea horologicalis Stosch, 1980 | − | + | − |
| Cerataulina sp. | + | + | − |
| Cerataulina bicornis (Ehrenberg) Hasle, 1985 | + | + | + |
| Cerataulina dentate Hasle in Hasle & Syvertsen, 1980 | + | + | + |
| Cerataulina pelagica (Cleve) Hendey, 1937 | − | + | − |
| Chaetoceros sp. | + | + | + |
| Chaetoceros affinis Lauder, 1864 | + | + | + |
| Chaetoceros coarctatus Lauder, 1864 | − | + | − |
| Chaetoceros concavicornis Mangin, 1917 | + | + | + |
| Chaetoceros constrictus* Gran, 1897 | + | − | − |
| Chaetoceros costatus* Pavillard, 1911 | − | + | − |
| Chaetoceros criophilus Castracane, 1886 | − | − | + |
| Chaetoceros curvisetus Cleve, 1889 | + | + | + |
| Chaetoceros debilis* Cleve, 1894 | − | − | + |
| Chaetoceros decipiens Cleve, 1873 | + | + | + |
| Chaetoceros dichaeta Ehrenberg, 1844 | − | + | − |
| Chaetoceros eibenii* Grunow, 1882 | + | + | + |
| Chaetoceros lorenzianus Grunow, 1863 | + | − | − |
| Chaetoceros mitra* (Bailey) Cleve, 1896 | + | − | − |
| Chaetoceros peruvianus Brightwell, 1856 | + | + | − |
| Chaetoceros pseudocurvisetus Mangin, 1910 | − | + | − |
| Climacodium frauenfeldianum Grunow, 1868 | − | + | − |
| Corethron pennatum* (Grunow) Ostenfeld, 1909 | − | − | + |
| Coscinodiscus sp. | + | − | + |
| Coscinodiscus granii Gough, 1905 | + | + | − |
| Coscinodiscus marginatus Ehrenberg, 1844 | + | + | − |
| Coscinodiscus radiates Ehrenberg, 1840 | + | + | + |
| Dactyliosolen sp. | − | + | − |
| Dactyliosolen fragilissimus (Bergon) Hasle, 1996 | + | + | + |
| Dactyliosolen phuketensis* (B.G.Sundström) G.R.Hasle, 1996 | + | + | + |
| Detonula pumila (Castracane) Gran, 1900 | + | + | + |
| Ditylum brightwellii (T.West) Grunow, 1885 | − | + | − |
| Ethmodiscus rex* (Wallich in Rattray) Hendey in Wiseman & Hendey, 1953 | + | + | − |
| Eucampia zodiacus Ehrenberg, 1839 | + | + | − |
| Guinardia sp. | + | − | − |
| Guinardia cylindrus (Cleve) Hasle, 1996 | + | + | + |
| Guinardia delicatula (Cleve) Hasle, 1997 | + | + | + |
| Guinardia flaccida (Castracane) H.Peragallo, 1892 | + | + | + |
| Guinardia striata (Stolterfoth) Hasle, 1996 | + | + | + |
| Helicotheca tamesis (Shrubsole) M.Ricard, 1987 | − | + | − |
| Hemiaulus hauckii Grunow ex Van Heurck, 1882 | + | + | + |
| Hemiaulus membranaceus Cleve | + | + | + |
| Hemiaulus sinensis Greville, 1865 | + | + | + |
| Hemidiscus cuneiformis Wallich, 1860 | + | − | + |
| Lauderia annulata Cleve, 1873 | + | + | + |
| Leptocylindrus danicus Cleve, 1889 | + | + | + |
| Leptocylindrus minimus* Gran, 1915 | + | + | + |
| Lithodesmium undulatum Ehrenberg, 1839 | + | + | + |
| Odontella aurita (Lyngbye) C.Agardh, 1832 | − | + | − |
| Paralia sulcate (Ehrenberg) Cleve, 1873 | + | + | − |
| Planktoniella sol (C.G.Wallich) Schütt, 1892 | + | + | − |
| Proboscia alata (Brightwell) Sundström, 1986 | + | ++ | + |
| Pseudoguinardia recta* von Stosch, 1986 | + | + | + |
| Pseudosolenia calcar-avis (Schultze) B.G.Sundström, 1986 | + | + | + |
| Rhizosolenia sp. | − | − | + |
| Rhizosolenia acicularis B.G.Sundström, 1986 | − | + | + |
| Rhizosolenia acuminate (H.Peragallo) H.Peragallo, 1907 | − | + | − |
| Rhizosolenia bergonii H.Peragallo, 1892 | + | − | − |
| Rhizosolenia castracanei* H.Peragallo, 1888 | − | − | + |
| Rhizosolenia clevei* Ostenfeld, 1902 | + | + | + |
| Rhizosolenia crassa* Schimper, 1905 | + | − | − |
| Rhizosolenia curvata* Zacharias, 1905 | + | + | + |
| Rhizosolenia formosa* H.Peragallo, 1888 | + | + | − |
| Rhizosolenia hebetate Bailey, 1856 | + | + | + |
| Rhizosolenia imbricate Brightwell, 1858 | + | + | + |
| Rhizosolenia ostenfeldii B.G.Sundström, 1986 | − | + | − |
| Rhizosolenia polydactyla* Castracane, 1886 | + | + | − |
| Rhizosolenia setigera Brightwell, 1858 | + | + | + |
| Rhizosolenia striata* Greville, 1864 | − | + | − |
| Rhizosolenia styliformis T.Brightwell, 1858 | + | + | + |
| Rhizosolenia temperei H.Peragallo, 1888 | − | + | − |
| Skeletonema costatum (Greville) Cleve, 1873 | + | + | + |
| Thalassiosira sp. | + | + | − |
| Thalassiosira subtilis (Ostenfeld) Gran, 1900 | + | + | − |
| Triceratium dubium Brightwell, 1859 | + | − | − |
| Pennate diatoms | |||
| Entomoneis alata (Ehrenberg) Ehrenberg, 1845 | + | + | + |
| Amphiprora gigantean Grunow, 1860 | + | + | + |
| Amphora sp. | + | + | − |
| Asterionellopsis glacialis (Castracane) Round, 1990 | + | ++ | + |
| Climacosphenia moniligera Ehrenberg, 1843 | + | ++ | + |
| Cylindrotheca closterium (Ehrenberg) Reimann & J.C.Lewin, 1964 | + | ++ | + |
| Diploneis smithii (Brébisson) Cleve, 1894 | + | − | − |
| Fragilaria sp. | − | + | + |
| Fragilaria striatula Lyngbye, 1819 | + | + | − |
| Gyrosigma fasciola (Ehrenberg) J.W.Griffith & Henfrey, 1856 | + | + | + |
| Haslea trompii (Cleve) Simonsen, 1974 | + | + | + |
| Haslea wawrikae* (Hustedt) Simonsen, 1974 | − | + | − |
| Licmophora abbreviate C.Agardh, 1831 | + | + | + |
| Licmophora flabellata (Grev.)C.Agardh, 1831 | + | + | − |
| Licmophora gracilis (Ehrenberg) Grunow, 1867 | + | + | − |
| Lioloma elongatum (Grunow) Hasle, 1997 | − | + | − |
| Meuniera membranacea (Cleve) P.C.Silva, 1996 | + | + | + |
| Navicula sp. | + | + | − |
| Navicula directa (W.Smith) Ralfs, 1861 | + | ++ | + |
| Navicula distans (W.Smith) Ralfs, 1861 | − | + | − |
| Navicula transitans Cleve, 1883 | + | + | + |
| Nitzschia sp. | + | + | + |
| Nitzschia acicularis* (Kützing) W.Smith, 1853 | + | − | − |
| Nitzschia longissimi (Brébisson) Ralfs, 1861 | + | + | + |
| Petrodictyon gemma (Ehrenberg) D.G.Mann, 1990 | − | − | − |
| Pleurosigma sp. | + | − | − |
| Pleurosigma directum Grunow, 1880 | + | + | − |
| Pleurosigma elongatum W.Smith, 1852 | + | + | + |
| Pleurosigma formosum W.Smith, 1852 | + | + | − |
| Pleurosigma normanii Ralfs, 1861 | − | − | + |
| Pseudo-nitzschia delicatissimaʘ (Cleve) Heiden, 1928 | +++ | +++ | + |
| Pseudo-nitzschia seriataʘ (Cleve) H.Peragallo, 1899 | + | + | + |
| Striatella unipunctata (Lyngbye) C.Agardh, 1832 | − | + | − |
| Synedra sp. | + | + | − |
| Synedra biceps* W.Smith, 1853 | + | − | − |
| Synedropsis hyperborea* (Grunow) G.R.Hasle, L.K.Medlin & E.E.Syvertsen, 1994 | + | − | − |
| Thalassionema bacillare (Heiden) Kolbe, 1955 | + | + | − |
| Thalassionema frauenfeldii (Grunow) Tempère & Peragallo, 1910 | + | + | − |
| Thalassionema nitzschioides (Grunow) Mereschkowsky, 1902 | − | − | + |
| Thalassiothrix longissimi Cleve & Grunow, 1880 | + | + | + |
| Toxarium undulatum Bailey, 1854 | + | + | − |
| Dinophyceae | |||
| Alexandrium sp. | + | + | + |
| Alexandrium affine (H.Inoue & Y.Fukuyo) Balech, 1995 | − | + | + |
| Alexandrium fundyenseʘ Balech, 1985 | − | + | − |
| Alexandrium minutumʘ Halim, 1960 | + | + | + |
| Alexandrium tamarenseʘ (Lebour, 1925) Balech, 1995 | + | + | + |
| Amphidinium sphenoides WüIff, 1916 | − | + | − |
| Amphisolenia bidentate Schröder, 1900 | − | + | − |
| Ceratocorys armata (Schütt) Kofoid, 1910 | + | + | − |
| Ceratocorys horrida Stein, 1883 | + | + | + |
| Corythodinium tesselatum (Stein) Loeblich Jr. & Loeblich III, 1966 | + | − | + |
| Dinophysis sp. | + | + | + |
| Dinophysis acuminataʘClaparède & Lachmann, 1859 | + | − | − |
| Dinophysis acutaʘEhrenberg, 1839 | + | − | − |
| Dinophysis caudataʘ Saville-Kent, 1881 | + | ++ | ++ |
| Dinophysis dens Pavillard, 1915 | + | − | − |
| Dinophysis hastate Stein, 1883 | + | + | + |
| Dinophysis milesʘ Cleve, 1900 | + | + | + |
| Dinophysis odiosa (Pavillard) Tai & Skogsberg, 1934 | + | + | + |
| Dinophysis triposʘ Gourret, 1883 | + | ++ | + |
| Dinophysis uracantha Stein, 1883 | + | + | − |
| Gonyaulax sp. | + | − | + |
| Gonyaulax polygramma Stein, 1883 | + | + | + |
| Gonyaulax scrippsae Kofoid, 1911 | + | − | − |
| Gonyaulax spiniferaʘ (Claparède & Lachmann) Diesing, 1866 | + | + | + |
| Gonyaulax verior Sournia, 1973 | + | + | + |
| Gymnodinium sp. | − | + | − |
| Heterocapsa triquetra (Ehrenberg) Stein, 1883 | − | − | + |
| Ornithocercus heteroporus* Kofoid, 1907 | + | − | − |
| Ornithocercus magnificus Stein, 1883 | + | − | − |
| Ornithocercus quadratus Schütt, 1900 | + | − | − |
| Ornithocercus splendidus Schütt, 1895 | + | + | + |
| Ornithocercus steinii Schütt, 1900 | + | − | − |
| Ornithocercus thumii* (Schmidt) Kofoid & Skogsberg, 1928 | + | + | + |
| Oxytoxum gracile Schiller, 1937 | + | + | − |
| Phalacroma sp. | + | − | − |
| Phalacroma cuneus F.Schütt, 1895 | + | + | − |
| Phalacroma doryphorum Stein, 1883 | + | + | + |
| Phalacroma mitraʘ F.Schütt, 1895 | + | − | − |
| Phalacroma oxytoxoides* (Kofoid) F.Gomez, P.Lopez-Garcia & D.Moreira, 2011 | − | − | + |
| Phalacroma rapa Jorgensen, 1923 | + | − | − |
| Phalacroma rotundatumʘ (Claparéde & Lachmann) Kofoid & Michener, 1911 | + | + | + |
| Podolampas palmipes Stein, 1883 | − | + | − |
| Podolampas spinifera Okamura, 1912 | − | + | − |
| Prorocentrum sp. | + | − | − |
| Prorocentrum cordatumʘ (Ostenfeld) J.D.Dodge, 1975 | + | + | + |
| Prorocentrum gracile Schütt, 1895 | + | + | + |
| Prorocentrum limaʘ (Ehrenberg) F.Stein, 1878 | + | + | − |
| Prorocentrum micansʘ Ehrenberg, 1834 | + | + | + |
| Prorocentrum triestinum J.Schiller, 1918 | + | + | + |
| Protoceratium reticulatum (Claparède & Lachmann) Bütschli, 1885 | − | + | − |
| Protoperidinium sp. | + | + | + |
| Protoperidinium bipes* (Paulsen, 1904) Balech, 1974 | + | + | + |
| Protoperidinium claudicans (Paulsen, 1907) Balech, 1974 | + | + | + |
| Protoperidinium conicum (Gran, 1900) Balech, 1974 † | + | ++ | ++ |
| Protoperidinium crassipes (Kofoid, 1907) Balech, 1974 | + | + | + |
| Protoperidinium curtipes (Jørgensen, 1912) Balech, 1974 | − | − | + |
| Protoperidinium depressum (Bailey, 1854) Balech, 1974 | − | + | + |
| Protoperidinium divergens (Ehrenberg, 1840) Balech, 1974 | + | ++ | ++ |
| Protoperidinium elegans (Cleve, 1900) Balech, 1974 | + | + | + |
| Protoperidinium grande (Kofoid, 1907) Balech, 1974 | + | − | + |
| Protoperidinium leonis (Pavillard, 1916) Balech, 1974 | − | + | + |
| Protoperidinium oblongum (Aurivillius) Parke & Dodge, 1976 | + | − | − |
| Protoperidinium oceanicum (VanHöffen, 1897) Balech, 1974 | + | + | + |
| Protoperidinium ovatum Pouchet, 1883 | + | + | + |
| Protoperidinium ovum (Schiller, 1911) Balech, 1974 | + | + | ++ |
| Protoperidinium pallidum (Ostenfeld, 1899) Balech, 1973 | + | + | ++ |
| Protoperidinium pellucidum Bergh, 1881 | + | + | + |
| Protoperidinium pentagonum (Gran, 1902) Balech, 1974 | + | + | + |
| Protoperidinium steinii (Jørgensen, 1899) Balech, 1974 | + | + | ++ |
| Pyrocystis lunula (Schütt) Schütt, 1896 | + | − | − |
| Pyrophacus steinii (Schiller) Wall & Dale, 1971 | − | + | + |
| Scrippsiella trochoidea (Stein) Loeblich III, 1976 | + | − | + |
| Tripos arietinus (Cleve) F.Gómez, 2013 | − | + | − |
| Tripos brevis (Ostenfeld & Johannes Schmidt) F.Gómez 2013 | + | + | + |
| Tripos candelabrus (Ehrenberg) F.Gómez, 2013 | + | + | − |
| Tripos carriensis (Gourret) F.Gómez, 2013 | + | + | + |
| Tripos contortus (Gourret) F.Gómez, 2013 | + | + | + |
| Tripos declinatus (G.Karsten) F.Gómez, 2013 | + | + | + |
| Tripos deflexus (Kofoid) F.Gómez, 2014 | + | + | − |
| Tripos furca (Ehrenberg) F.Gómez, 2013 | + | ++ | ++ |
| Tripos fusus (Ehrenberg) F.Gómez 2013 | + | ++ | ++ |
| Tripos gibberus (Gourret) F.Gómez 2013 | + | + | − |
| Tripos horridus (Cleve) F.Gómez 2013 | + | ++ | + |
| Tripos incisus (Karsten) F.Gómez, 2013 | − | + | + |
| Tripos inflatus (Kofoid) F.Gómez 2013 | + | + | + |
| Tripos kofoidii (Jörgenen) F.Gómez, 2013 | − | + | − |
| Tripos lineatus (Ehrenberg) F.Gómez, 2013 | + | ++ | + |
| Tripos longipes (J.W.Bailey) F.Gómez, 2013 | + | + | − |
| Tripos lunula (Schimper ex Karsten) F.Gómez, 2013 | + | + | + |
| Tripos macroceros (Ehrenberg) F.Gómez, 2013 | + | + | + |
| Tripos pentagonus (Gourret) F.Gómez, 2013 | + | + | − |
| Tripos platycornis (Daday) F.Gómez 2013 | + | − | − |
| Tripos praelongus (Lemmermann) Gómez, 2013 | − | − | + |
| Tripos pulchellus (Schröder) F.Gómez, 2013 | + | + | + |
| Tripos ranipes (Cleve) F.Gómez, 2013 | + | + | − |
| Tripos symmetricus (Pavillard) F.Gómez 2013 | + | + | + |
| Tripos teres (Kofoid) F.Gómez 2013 | + | ++ | + |
| Tripos trichoceros (Ehrenberg) Gómez 2013 | + | + | + |
| Tripos vultur (Cleve) F.Gómez, 2013 | + | + | + |
| Cyanophyceae | |||
| Anabaena sp. | − | + | − |
| Nostoc sp. | − | + | − |
| Richelia intracellularis J.Schmidt, 1901 | + | + | + |
| Trichodesmium sp. | ++ | ++ | + |