https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:20310 Wed 12 Oct 2022 10:11:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:11003 Wed 12 May 2021 23:47:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36047 Wed 12 May 2021 23:37:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2381 Wed 12 May 2021 23:30:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:33223 Wed 12 May 2021 23:29:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36597 Wed 12 May 2021 23:10:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5492 Wed 12 May 2021 23:08:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:6673 Wed 12 May 2021 22:51:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4618 Wed 12 May 2021 22:41:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:8079 Wed 12 May 2021 22:32:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1554 Wed 12 May 2021 22:25:57 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36044 Wed 12 May 2021 22:18:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3424 Wed 12 May 2021 20:36:56 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36136 Wed 12 May 2021 20:32:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36534 Wed 12 May 2021 20:31:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36130 Wed 12 May 2021 20:20:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36042 Wed 12 May 2021 20:20:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36048 Wed 12 May 2021 20:19:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2974 Wed 12 May 2021 20:15:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36046 Wed 12 May 2021 20:06:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36139 Wed 12 May 2021 19:53:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2966 Wed 12 May 2021 19:51:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10760 Wed 12 May 2021 19:16:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4095 Wed 12 May 2021 19:10:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2972 Wed 12 May 2021 18:54:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36378 Wed 12 May 2021 18:53:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1800 Wed 12 May 2021 18:53:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:11089 Wed 12 May 2021 18:52:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36137 Wed 12 May 2021 18:51:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36465 Wed 12 May 2021 18:50:55 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1135 Wed 12 May 2021 18:31:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36041 Wed 12 May 2021 18:27:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1000 Wed 12 May 2021 18:20:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:30240 Wed 12 May 2021 17:55:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2186 Wed 12 May 2021 17:33:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36466 Wed 12 May 2021 17:22:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3673 Wed 12 May 2021 17:09:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3899 Wed 12 May 2021 17:09:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36536 Wed 12 May 2021 16:38:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36540 Wed 12 May 2021 16:28:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36045 Wed 12 May 2021 16:08:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1533 Wed 12 May 2021 15:44:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:39938 Wed 12 May 2021 15:10:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:40754 Wed 12 May 2021 15:01:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:42652 Wed 12 May 2021 14:44:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:54489 Wed 10 Aug 2022 12:53:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:54495 Wed 10 Aug 2022 12:53:18 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:38194 Wed 08 May 2024 19:27:24 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:44212 Wed 08 May 2024 17:31:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:57069 Thu 29 Sep 2022 17:09:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5270 Thu 15 Jul 2021 20:34:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36135 Thu 13 May 2021 13:16:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2962 Thu 13 May 2021 11:30:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5765 50% of total chlorophyll-a at all these stations. Xl Within the IFZ (2 stations), nanophytoplankton dominated total integrated Chl-a biomass (range between 5.6 and 8.8 mg Chi-a. m-2) comprising, on average, 36% of the total. Picophytoplankton comprised an average of 12% of the total Chl-a biomass (range between 3.1 and 5.9 mg Chi-a. m-2) in the MIZ, 36% in the IFZ (range between 6.4 and 7.8 mg Chl-a . m-2) and 20% in the vicinity of the APF (range between 6.8 and 10.6 mg Chi-a. m-2). Total integrated primary production ranged between 316 and 729 mg C . m-2. d-1 at stations occupied in the vicinity of the MIZ, and between 292 and 317 mg C . m·2• d-l within the IFZ. At stations occupied in the region of the APF, total integrated production ranged between 708 and 926 mg C . m-2• dol. The contribution of various size fractions to total productivity generally displayed the same pattern as integrated Chl-a biomass. Microphytoplankton formed the most important contributor to total production at stations occupied in the MIZ and at the APF. Within the IFZ, nanophytoplankton dominated total daily production. Nutrient data suggest that concentrations of macro nutrients within the upper water column were above the threshold where growth would be limited. Preliminary results showed that concentrations of iron (Fe) were highest in the southern region of the MIZ and in the vicinity of the APF. During the second cruise, conducted in the vicinity of the Sub-Antarctic Front (SAF) and in the upstream, inter-island and downstream regions of the Prince Edward Islands, there was evidence of fresh water run-off from the islands, (i.e. decreased salinities and increased concentrations of ammonia and nitrate). Oceanographic data collected at the various production stations indicated that the upper water column was well mixed throughout the survey. Total integrated biomass during the study ranged between 8.5 and 20.1 mg Chi-a. m-2• No distinct patterns in total Chl-a biomass were evident. Picophytoplankton dominated total biomass comprising> 45 % of total pigment at all stations. Nanophytoplankton were the second most important contributor to total integrated biomass. Generally xu microphytoplankton contributed < 10 % of total ChI-a. Total daily integrated production was highest (442.6 mg Chi-a. m-2) at the single station occupied in the vicinity of the SAF. Outside this region, total areal production was lower, ranging from 94.5 to 353.0 mg C . m-2. d-1. With the exception of the station occupied in the vicinity of the SAF, total productivity was dominated by nanophytoplankton, which comprised between 48 and 66% of the total. Concentrations of macronutrients did not appear to be limiting to phytoplankton growth. The absence of a phytoplankton bloom in the vicinity of the islands appears to have been related to water column stability, which was influenced by the prevailing oceanographic regime during the survey. Previous studies have shown that when the SAF lies in close proximity to the islands, advecting forces prevail, resulting in the islands functioning as a flow-through system. During this study, the SAF lay immediately north of the islands. As a consequence no water was trapped in the leeward side of the islands. The results of the two cruises suggest that phytoplankton production in the four systems investigated: the Marginal Ice Zone (MIZ), Antarctic Polar Front (APF), Inter Frontal Zone (IFZ) and Prince Edward Islands (PEl), was largely controlled by water column stability. It is probable that the availability of iron, particularly in the region of the MIZ and APF, may have further contributed to the elevated production recorded in these two regions.]]> Thu 13 May 2021 10:40:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3190 Thu 13 May 2021 08:55:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36542 Thu 13 May 2021 07:25:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36379 Thu 13 May 2021 07:03:55 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2973 Thu 13 May 2021 06:58:58 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2925 Thu 13 May 2021 06:57:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36533 Thu 13 May 2021 06:56:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5354 70%) throughout the estuary, with two distinct groups being identified on the basis of substratum type. The sampling stations near the mouth with a sandy substratum were distinguished from all other sampling sites in the estuary. The dominant estuarine-spawning species were represented by all life-history stages, suggesting that they bred successfully in the estuary. This group was numerically and gravimetrically dominated by the two zooplanktivorous shoaling species Gilchristella aestuaria and Atherina breviceps with density extrapolated population size estimates of 420 973 and 198 275 individuals, and biomass estimates of 1.6 and 0.6 g m⁻² respectively. The total population size of all estuarine-spawning species with a mean biomass 00.4 g m⁻² was estimated at 754 217 individuals. Population size estimates of the marine-spawning species were calculated using data obtained from three independent mark-recapture experiments. The assumptions for the mark-recapture analyses were adequately met and it was concluded that the techniques provided reliable estimates of population size. However, estimates obtained from density extrapolation revealed enormous variability and were considered to be unreliable. The total population size was estimated at 63 342, 18 592 and 13 5 192 during the three mark-recapture experiments respectively. The numerically dominant species during all three experiments was Rhabdosargus holubi. Biomass production of the marine-spawning species was evaluated over a 123 day census period when population sizes and estimates of growth rates were known. Productivity for all fishes with a standing stock of 26.2 g m⁻² was calculated at 4.5 g m⁻² month01 Rhabdosargus holubi accounted for more than 75% of the total marine fish productivity. This study draws attention to the success of Rhabdosargus holubi in the East Kleinemonde estuary, which is ascribed to aspects of its biology. These include an extended breeding season, the ability to recruit into the estuary under adverse open mouth conditions and its omnivorous food habits. The dominance of this migratory species suggests that it plays an important role in the transfer of energy to the coastal marine environment when the mouth of the East Kleinemonde estuary opens. Predation by birds and a dominant piscivorous fish (Lichia amia) was quantitatively assessed over a period of two years. Monthly food consumption by all piscivorous birds revealed large temporal variability, ranging from 32 to 466 kg month-I An unusual invasion of Cape cormorants during the winter of 1994 accounted for large scale mortality (2246 kg of fish) over a relatively short period. The predatory impact of this episodic event was reflected in the findings of the fish mark-recapture experiments, which revealed a 70% reduction in the total population of marine-spawning fishes (above a certain minimum size) in the estuary subsequent to this invasion. Monthly food consumption by the Lichia amia population in the estuary was calculated at 68 and 58 kg month-I for two distinct time periods when the population size was known. These findings suggest that this species is the top piscivorous predator in the East Kleinemonde estuary. Finally, the findings of this study highlight the temporal variability of fish populations within a single estuary. It is suggested that predation and estuary mouth conditions are the main factors influencing the abundance (and its variability) of individual species in the East Kleinemonde estuary.]]> Thu 13 May 2021 06:28:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4832 Thu 13 May 2021 06:26:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2932 Thu 13 May 2021 06:19:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:6135 Thu 13 May 2021 06:15:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36138 Thu 13 May 2021 06:13:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36467 Thu 13 May 2021 06:00:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36127 Thu 13 May 2021 05:46:58 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36129 Thu 13 May 2021 05:34:24 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36464 Thu 13 May 2021 05:15:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3904 Thu 13 May 2021 05:05:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36596 Thu 13 May 2021 04:56:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36468 Thu 13 May 2021 04:46:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:5322 Thu 13 May 2021 04:37:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1241 Thu 13 May 2021 04:27:40 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2394 Thu 13 May 2021 04:25:02 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36381 Thu 13 May 2021 04:18:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36531 Thu 13 May 2021 03:33:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36444 Thu 13 May 2021 03:05:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36537 Thu 13 May 2021 03:05:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3668 Thu 13 May 2021 03:04:24 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36043 Thu 13 May 2021 02:49:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36132 Thu 13 May 2021 02:49:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3420 Thu 13 May 2021 02:40:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36447 Thu 13 May 2021 02:30:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2921 Thu 13 May 2021 02:25:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36134 Thu 13 May 2021 02:16:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2995 Thu 13 May 2021 02:10:58 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:38880 Thu 13 May 2021 02:06:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36382 Thu 13 May 2021 02:04:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:691 Thu 13 May 2021 01:51:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36532 Thu 13 May 2021 01:39:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36463 Thu 13 May 2021 01:15:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:10826 Thu 13 May 2021 01:09:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:8078 Thu 13 May 2021 00:55:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36529 Thu 13 May 2021 00:51:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:36131 Thu 13 May 2021 00:35:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3248 Thu 13 May 2021 00:26:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:2969 Thu 13 May 2021 00:06:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:40622 Thu 01 Feb 2024 09:08:12 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:1501 Mon 26 Jun 2023 11:56:49 SAST ]]>