https://commons.ru.ac.za/vital/access/manager/Index en-us 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:5746 0.05). At a constant temperature (20°C), the oxygen consumption rate of M. wooldridgei decreased with an increase in salinity. Salinity tolerance of the mysid was strongly modified by temperature. At 5‰ and 30°C, mysids exhibited mass mortality. The Q10 value for M. wooldridgei at 15, 25 and 35‰ was estimated at 2.34, 1.44 and 2.14, respectively. Results of the study suggest that M. wooldridgei is well adapted to surviving in environments characterised by variations in temperature and salinity. Within the Great Fish Estuary, total chl. a concentration ranged between 2.68 μg L-1 and 31.12 μg L-1 and was always dominated by large phytoplankton cells (>5 μm). Average zooplankton abundance ranged between 62 and 28 917 ind. m-3 and biomass between 10 and 203 mg Dwt m-3. The zooplankton community was numerically dominated by the calanoid copepod Pseudodiaptomus hessei, which comprised up to 100% (range between 12 and 100%) of the total zooplankton counted. Total zooplankton biomass during the day was dominated by copepods and by mysids during the nighttime. Among the mysids, M. wooldridgei was the most numerically abundant mysid and comprised <10% of the total zooplankton abundance. Numerical analysis found no seasonal pattern in the total zooplankton abundance (including mysids). The lack of any seasonality could be attributed to the continuous freshwater inflow into the estuary due to the inter-basin transfer of water from the Gariep Dam to the Fish River system. A distinct spatial pattern in the zooplankton community structure was evident with the upper stations almost entirely dominated by the copepod P. hessei, while at stations occupied in the lower reaches of the estuary, the zooplankton community comprised a mixture of freshwater, estuarine and marine breeding zooplankton species. The mysids also demonstrated a distinct spatial pattern in their distribution. Mysids were generally absent from the upper reaches, while in the middle reaches Rhopalophthalmus terranatalis and M. wooldridgei were numerically dominant. Gastrosaccus brevifissura dominated in the lower regions of the estuary. Stable isotope analysis (δ13C) indicated that the dominant source of carbon utilised by the numerically dominant copepods and juvenile M. wooldridgei within the estuary was derived from the extensive phytoplankton stocks within the system. In contrast, sub-adult and adult mysids (R. terranatalis, M. wooldridgei and G. brevifissura) appeared to consume a combination of phytoplankton and copepods. The contribution of the various sources of carbon to the total carbon intake of the mysid remains unknown.]]> Wed 12 May 2021 23:42:36 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5704 7mm) were equivalent to ≈10% and ≈5% of body dry weight, respectively. The von Bertalanffy growth curve parameters were empirically identified, by cohort analysis of data collected during 4 years, as K = 0.22239/year, L[subscript]∞ = 14.05789mm, t₀ = -0.05174, L₀ = 0.16083mm. N. marionis can survive up to seven years under natural conditions.]]> Wed 12 May 2021 22:28:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5742 0.05 in all other cases). There were two distinct spatial patterns in the distribution of the larger ichthyofauna (>50mm SL). These corresponded to a grouping associated with the mouth region and a grouping associated with the remaining regions of the estuary. Stable isotope analysis indicated that the primary source of carbon utilised by the ichthyofauna of the Kasouga estuary was derived from the channel, most likely microphytobenthic algae. The contributions of the riparian and salt marsh vegetation to the total carbon flow appear to be minimal.]]> Wed 12 May 2021 18:18:06 SAST ]]>