Euryhaline zooplankton of the Sundays estuary and notes on trophic relationships

Spatial and temporal patterns of habitat use by three estuarine species of mysid shrimp

“…This suggests there may be a juvenile and adult subpopulation partitioning their distribution, with juveniles using the hyperbenthos during the day and adults at night. This explains the surprising lack of a diel relationship for numbers of R. egregius, which was also observed in congeneric Rhopalophthalmus terrantalis (Wooldridge and Bailey 1982). Rhopalophthalmus spp.…”

“…Rhopalophthalmus spp. adults are cannibalistic (Wooldridge and Bailey 1982), and adults and juveniles have been known to segregate to minimize cannibalistic interactions (Mauchline 1980). Kouassi et al (2006) found DVM and diurnal feeding behaviour in congeneric Rhopalophthalmus africana, with numbers of juvenile mysids at the surface peaking during the night, and adult numbers peaking during the day.…”

A comparison of the fish communities in nearby permanently open, seasonally open and normally closed estuaries in the South-Western Cape, South Africa

“…A therina breviceps, Caffrogobius multifasciatus, Hyporhamphus capensis and Psammogobius knysnaensis all lay large eggs with threads which attach to some fixed substratum. Only Gilchristella aestuarius has free-floating eggs (Wooldridge and Bailey 1982), though Talbot (1982) states that, in the Swartkops Estuary (33°52'S, 25°38'E) at least, these are spawned in the extreme upper reaches. Loss of eggs to the sea by these species is further reduced by the fact that all except C. spatulatus breed during summer, when rainfall is at a miniinum and most of the estuaries are closed or, if open, water currents are at a minimum.…”

The response ofGrandidierella lignorum(Barnard) (Crustacea: Amphipoda) to episodic flooding in three eastern Cape estuaries

“…Low salinity areas occupied by G. lignorum and P. hessei are unfavourable for major predators such as Mesopodopis slabberi and Rhopalopthalamus terranatalis (Wooldridge & Bailey 1982). Thus during periods of increased river discharge, P. hessei and G. lignorum which are physiologically adapted to low salinity, could exploit planktonic food resources in the absence of invertebrate predators.…”

“…1989,24(2) abundance are evident in the Keiskamma estuary (Figure 4), possibly a result of unseasonal elevated freshwater inflows. Wooldridge & Melville- Smith (1979) and Wooldridge & Bailey (1982) reported that an increase in river discharge also leads to an increase in the population density of the copepod Pseudodiaptomus hessei. Although Grindley (1970) observed seasonal changes in the abundance of P. hessei, these were not evident in the Sundays estuary (Wooldridge & MelvilleSmith 1979) owing to unseasonal increased river inflows to which P. hessei responded.…”