Spatial distribution of phytoplankton in the eastern part of the North ...

More documents

Recommendations

Info

part of the transect (e.g. P. pyriformeor P. subinerme) or only at one station(e.g. P. marielebouriae, quite commonat station 145, but not found at nearbystations). Generally, the highestoccurrence of Protoperidinium specieswas noted at stations 153 and 151, inthe central part of the transect.Towards both ends of the transect,decreasing total relative abundance of Figure 12. Spatial variation in the relative abundancespecies was noted. Only at the coastal of Protoperidinium species.station 145, high abundance of P. achromaticum together with the presence of 3 unique speciescaused the increase of species abundance (Fig. 12).‣ Prasinophyceae – In total, 5 species belonging to this group were found in the transect.Apart from Halosphaera viridis, found in the western part of the transect, all other species belongedto the genus Pterosperma. Species ofthis genus are mainly distinguished bythe structure of the phycoma stage,bearing a distinct equatorial keel or asystem of keels, dividing its surfaceinto polygons. Pterosperma cristatum,appeared in the western and centralparts of the transect, and the threeother species were found only in thecentral part of the study area (Fig. 13). Figure 13. Spatial variation in the relative abundanceof Pterosperma species.This is in accordance with cellabundance, which was highest in the same, central area of the transect (Fig. 5c).‣ Chlorophyceae – Only three species of this group were found – Pediastrum boryanum,Pediastrum cf. kawraiskyi and Scenedesmus sp. Pediastrum boryanum was found at the six stationsin the eastern part of the transect, while Scenedesmus sp. and Pediastrum cf. kawraiskyi were onlyfound at stations 145 and 143, respectively, nearest the coast.15
3.4. Differences in algal composition of bottom and surface water levelsAt four stations (every second station in the transect), the differences between bottom andsurface species composition were investigated. In this survey, a total of 70 species was foundaltogether at the four stations (46 diatoms, 17 dinoflagellates, 7 species belonging to other groups ofalgae). Most species exhibited the same abundance in both bottom and surface water samples,however several species, in the two largest groups of algae, showed a distinct vertical gradient. Therelative abundances of species, occurred in the bottom and surface water samples, are given in Tab. 8.Interestingly, several diatoms were found to be more abundant in bottom water samples(Asterionellopsis glacialis, Pleurosigma lanceolatum, Neostreptotheca subindica and Nitzschialongissima), while only Podosira stelliger was found more often in surface water samples. Theopposite pattern was found in two dinoflagellate species (Ceratium lineatum and Protoperidiniumachromaticum), which were more abundant in surface water samples. No dinoflagellate speciesoccurred with higher abundance in bottom water samples.In Fig. 14, showing the vertical gradient of diatom species abundance, the greatest differencebetween bottom and surface water species composition is apparent at station 153. There, the totalnumber of species occurring in surface or bottom water samples was 24 and 30, respectively. At thesame station, the inverse vertical gradient of dinoflagellate species was noted (Fig. 15). Due to thevery small number of species found from other algal classes, vertical gradients were interpretedonly for the two previously mentioned algal groups.Figure 14. Horizontal and vertical variationin the number of diatom species found. Redcolour indicates the areas with the highestspecies richness.Figure 15. Horizontal and vertical variationin the number of dinoflagellate speciesfound. Red colour indicates the areas withthe highest species richness.16
Page 5: getting deeper towards the north. I
Page 10: The values varied between 32.7 and
Page 14 and 15: However, no single Chaetocerosspeci
Page 18 and 19: 3.5. Results of statistical analyse
Page 20: The first ordination axis, characte
Page 23 and 24: values of fluorescence but they wer
Page 26: 5. ConclusionsThe data for this sur
Page 29 and 30: REID, F.M.H.; STEWARD, E.; EPPLEY,
Page 32 and 33: Taxon / Number of station Fig. 123
Page 34 and 35: Taxon/number of station 157 153 149
Page 36 and 37: Plate I. Craspedophyceae, Chrysophy
Page 38 and 39: Plate III. Bacillariophyceae 2.1. C
Page 40 and 41: Plate V. Bacillariophyceae 4.1., 2.
Page 42 and 43: Plate VII. Bacillariophyceae 6.1. T
Page 44 and 45: Plate IX. Dinophyceae 2.1.-3. Penta
Page 46 and 47: Plate XI. Dinophyceae 4.1., 2. Prot

Spatial distribution of phytoplankton in the eastern part of the North ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?