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Table 1 General information on diatom assemblages recorded in the springs of 1993, 1994 and 1995

From: Latitudinal patterns and interannual variations of spring phytoplankton in relation to hydrographic conditions of the southwestern Atlantic Ocean (34°–62°S)

  1993 1994 1995
Total    
 Number of species recorded 173 162 103
 Mean number and range of species per station 50 (34–86) 51 (31–73) 27 (16–42)
 Dominant species (mean relative abundance) F. kerguelensis (20 %) C. contortus (16 %) F. kerguelensis (35 %)
  T. nitzschioides (8 %) F. kerguelensis (11 %) C. criophilum (15 %)
F. doliolus (6 %) C. debilis (10 %) T. nitzschioides (7 %)
C. rostratus (5 %) B. hyalinum (6 %) A. hookeri (5 %)
 Common species (present in >70 % of the samples) A. tabularis A. tabularis A. tabularis
  A. curvatulus A. curvatulus A. curvatulus
C. criophilum C. criophilum A. parvulus
T. nitzschioides C. decipiens F. kerguelensis
F. kerguelensis F. kerguelensis T. nitzschioides
TZ    
 Mean number and range of species per station 53 (34–87) 57 (27–73) 28 (18–42)
 Proportion of cold-water species 16 % 13 % 25 %
 Relative cell abundance of cold-water species 8 % 0.9 % 20 %
 Relative cell abundance of warm-water species 44 % 89 % 31 %
 Dominant species (mean relative abundance) F. doliolus (12 %) C. contortus (38 %) C. criophilum (21 %)
T. nitzschioides (12 %) B. hyalinum (13 %) T. nitzschioides (13 %)
C. rostratus (10 %) P. multiseries (5 %) F. kerguelensis (10 %)
F. kerguelensis (5 %)
SAZ    
 Mean number and range of species per station 41 (37–50) 36 (31–42) 26 (22–31)
 Proportion of cold-water species 51 % 49 % 62 %
 Relative cell abundance of cold-water species 68 % 68 % 89 %
 Relative cell abundance of warm-water species 1.2 % 4.8 % 0.42 %
 Dominant species (mean relative abundance) F. kerguelensis (42 %) F. kerguelensis (37 %) F. kerguelensis (60 %)
C. convolutus (8 %) C. atlanticus (11 %) A. hookeri (7 %)
E. antarctica (7 %) P. lineola (10 %) F. ritscheri (5 %)
AZ    
 Mean number and range of species per station 48 (40–56) 50 (38–63) 25 (16–32)
 Proportion of cold-water species 67 % 62 % 87 %
 Relative cell abundance of cold-water species 81 % 58 % 97 %
 Relative cell abundance of warm-water species 0.06 % 1.2 % 0 %
 Dominant species (mean relative abundance) F. kerguelensis (37 %) C. debilis (32 %) F. kerguelensis (29 %)
C. criophilum (5 %) F. kerguelensis (19 %) A. hookeri (22 %)
P. lineola (5 %) P. lineola (8 %) A. hyalinus (9 %)
P. heimii (5 %)
  1. The biogeographic areas defined are Transitional Zone (TZ), Subantarctic Zone (SAZ) and Antarctic Zone (AZ). Species names in Figs. 5 and 6