6  - Zooplankton Volume - Seasonal Cycles

Seasonal variations of zooplankton displacement volume for the CalCOFI standard grid and for subareas are described through monthly means and the one-standard deviation interval for the exponential distribution.  Listed below are the month (1 - 12), the monthly means (MesoZoo - ml per 1000 m³ calculated from log-normalized data), the lower (StDev (-)) and upper (StDev (-) limits of the one standard deviation interval (calculated from log-normalized data), and the number of samples calculations were based on.  These parameters are calculated for the CalCOFI Standard Grid for the 1951 - 1998, 1951 - 1985 and the 1986 - 1998 time periods.  For subareas these parameters are only calculated for the 1951 - 1985 and the 1986 - 1998 time periods.   Note that for most areas June and December are not well covered for the 1986 - 1998 time period.  The one StDev interval associated with all means is generally very large; the upper value is in most cases 2 to 3 times larger than the mean. Seasonal variations of zooplankton biomass for some subareas suggest a simple harmonic, other do not; thus harmonic coefficients were not calculated. 

A comparison of the 1951 - 1985 and the 1986 - 1998 data clearly shows the dramatically lower zooplankton abundance during the latter time period throughout the annual cycle for all subareas with the possible exception of the Santa Barbara Basin.  It is evident from these data that the amplitude of the annual cycle, when normalized to the mean annual value, is greatly reduced during the 1986 - 1998 time period compared to the 1951 - 1985 period.  

Standard CalCOFI Grid                 1951 - 1998                                         Month MesoZoo StDev (-) StDev (+) n             1 76 29 204 1357             2 92 36 235 1265             3 98 38 255 1097             4 103 36 299 1671             5 174 61 498 1273             6 191 72 506 893             7 151 51 447 1468             8 108 36 319 716             9 71 26 196 618             10 74 28 193 1181             11 63 22 183 643             12 78 31 198 487                                   Standard CalCOFI Grid                 1951 - 1985         1986 - 1998                             Month MesoZoo StDev (-) StDev (+) n   Month MesoZoo StDev (-) StDev (+) n 1 96 36 254 960   1 45 21 95 397 2 103 41 262 1010   2 58 25 133 255 3 109 42 283 875   3 65 28 150 222 4 143 56 369 1182   4 47 19 115 489 5 199 73 538 1063   5 91 31 262 210 6 197 76 510 873   6 46 16 136 20 7 199 72 548 1110   7 65 28 149 358 8 159 56 453 397   8 66 26 168 319 9 91 33 253 374   9 48 20 117 244 10 95 36 247 777   10 46 21 98 404 11 82 30 223 393   11 41 15 116 250 12 80 32 205 464   12 41 24 69 23

Southern California Bight Coastal             1951 - 1985         1986 - 1998                             Month MesoZoo StDev (-) StDev (+) n   Month MesoZoo StDev (-) StDev (+) n 1 75 30 185 252   1 49 24 97 102 2 91 37 224 266   2 63 31 128 54 3 101 42 243 234   3 76 39 150 56 4 151 64 356 271   4 69 29 166 118 5 202 74 548 250   5 186 78 441 49 6 172 65 458 195   6 76 29 202 6 7 187 65 533 272   7 78 32 189 92 8 164 57 472 103   8 74 39 140 68 9 86 27 279 110   9 48 17 133 64 10 84 34 209 224   10 49 25 95 95 11 57 21 152 104   11 39 17 94 62 12 67 27 163 166   12 47 30 72 10

                                                                                                                                                                                 

Southern California Bight               1951 - 1985         1986 - 1998                             Month MesoZoo StDev (-) StDev (+) n   Month MesoZoo StDev (-) StDev (+) n 1 93 32 269 256   1 47 25 88 118 2 102 41 257 316   2 60 29 123 54 3 105 43 258 267   3 70 33 152 60 4 161 74 349 318   4 54 23 123 116 5 257 102 649 305   5 108 59 201 57 6 261 107 632 250   6 98 41 234 6 7 240 87 660 303   7 86 42 175 95 8 174 66 460 108   8 68 34 134 75 9 85 31 234 130   9 53 26 110 68 10 100 36 279 241   10 45 21 97 99 11 84 27 257 136   11 42 17 100 63 12 91 32 254 154   12 43 27 67 7

California Current               1951 - 1985         1986 - 1998                             Month MesoZoo StDev (-) StDev (+) n   Month MesoZoo StDev (-) StDev (+) n 1 93 32 269 256   1 47 25 88 118 2 102 41 257 316   2 60 29 123 54 3 105 43 258 267   3 70 33 152 60 4 161 74 349 318   4 54 23 123 116 5 257 102 649 305   5 108 59 201 57 6 261 107 632 250   6 98 41 234 6 7 240 87 660 303   7 86 42 175 95 8 174 66 460 108   8 68 34 134 75 9 85 31 234 130   9 53 26 110 68 10 100 36 279 241   10 45 21 97 99 11 84 27 257 136   11 42 17 100 63 12 91 32 254 154   12 43 27 67 7

California Current Offshore (stations 90 - 120)           1951 - 1985         1986 - 1998                             Month MesoZoo StDev (-) StDev (+) n   Month MesoZoo StDev (-) StDev (+) n 1 82 31 216 118   1 29 12 67 110 2 80 29 217 118   2 33 17 65 73 3 64 23 175 107   3 33 16 69 50 4 70 25 198 156   4 21 10 44 136 5 92 36 234 128   5 27 12 62 41 6 101 41 245 93   6 14 9 21 4 7 116 40 335 125   7 28 17 47 104 8 54 29 101 52   8 25 12 54 94 9 51 30 88 32   9 27 13 56 69 10 58 29 116 89   10 27 13 55 121 11 71 29 173 35   11 25 9 71 68 12 54 25 113 30   12 31 12 81 3

SB-Basin (Line 81.8 Station 46.7)               1951 - 1985         1986 - 1998                             Month MesoZoo StDev (-) StDev (+) n   Month MesoZoo StDev (-) StDev (+) n 1 63 24 161 11   1 47 25 88 118 2 79 28 223 13   2 60 29 123 54 3 103 74 144 8   3 70 33 152 60 4 300 151 596 15   4 54 23 123 116 5 150 30 742 9   5 108 59 201 57 6 330 186 583 10   6 98 41 234 6 7 276 86 885 14   7 86 42 175 95 8 274 69 1082 5   8 68 34 134 75 9 128 59 281 3   9 53 26 110 68 10 82 28 236 11   10 45 21 97 99 11 48 12 189 5   11 42 17 100 63 12 63 44 90 5   12 43 27 67 7

Point Conception Area                 1951 - 1985         1986 - 1998                             Month MesoZoo StDev (-) StDev (+) n   Month MesoZoo StDev (-) StDev (+) n 1 121 49 299 150   1 87 49 153 26 2 162 67 391 106   2 80 28 231 44 3 214 88 523 103   3 184 94 362 21 4 253 101 634 148   4 89 40 199 59 5 298 136 654 113   5 255 124 522 21 6 284 118 680 87   6 n.d. n.d. n.d. n.d. 7 279 129 603 124   7 118 60 231 31 8 294 112 776 52   8 171 81 361 46 9 178 57 553 27   9 104 43 250 17 10 134 57 314 81   10 78 32 190 50 11 103 52 207 55   11 63 26 151 31 12 99 38 257 45   12 n.d. n.d. n.d. n.d.

Central California Inshore               1951 - 1985         1986 - 1998                             Month MesoZoo StDev (-) StDev (+) n   Month MesoZoo StDev (-) StDev (+) n 1 141 60 332 298   1 81 51 129 11 2 198 91 430 152   2 83 25 280 28 3 305 128 728 147   3 131 78 219 18 4 325 114 924 352   4 83 39 177 59 5 409 165 1016 214   5 232 103 524 12 6 329 133 815 175   6 n.d. n.d. n.d. n.d. 7 356 163 778 282   7 133 82 214 19 8 377 168 846 78   8 194 80 469 28 9 266 119 598 28   9 97 39 244 8 10 169 73 392 139   10 79 31 201 40 11 156 59 411 81   11 81 34 194 19 12 171 68 432 74   12 n.d. n.d. n.d. n.d.

Central California Offshore               1951 - 1985         1986 - 1998                             Month MesoZoo StDev (-) StDev (+) n   Month MesoZoo StDev (-) StDev (+) n 1 153 59 397 168   1 67 28 156 15 2 135 51 353 140   2 45 20 102 28 3 183 65 516 151   3 70 37 133 23 4 200 63 631 284   4 40 21 76 72 5 253 81 789 209   5 64 24