Episodic events: The effects of cyclonic flushing on the ichthyoplankton of St Lucia estuary on the southeast coast of Africa

Martin, T. J.; Cyrus, D. P.; Forbes, A. T.

doi:10.1016/0077-7579(92)90065-m

Cited by 48 publications

(33 citation statements)

References 7 publications

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“…fish) having been the subject of ongoing research over many decades. Examples of these studies include the geomorphology of the area (Hobday, 1975), sedimentology (Wright and Mason, 1990), salinity (Hutchison and Midgely, 1978), turbidity (Cyrus and Blaber, 1988), hydrology (Pitman, 1980), suspensoids (Fielding et al, 1991;Lindsay et al, 1996), phytoplankton (Johnson, 1977), microphytobenthos (Bate and Smailes, 2008), macrophytes (Breen et al, 1976;Steinke and Ward, 1987), zooplankton (Grindley, 1976), zoobenthos (Boltt, 1975;Blaber et al, 1983;Owen and Forbes, 1997;Pillay and Perissonotto, 2008a), hyperbenthos (Benfield et al, 1990;Fielding et al, 1990;Carrasco et al, 2007), meiofauna (Pillay and Perissonotto, 2008b), ichthyofauna (Whitfield and Blaber, 1978;Blaber, 1979;Harris and Cyrus, 1995;Cyrus and Vivier, 2006a;Whitfield et al, 2006), avifauna (Whitfield and Cyrus, 1978;Berruti, 1983), reptiles (Pooley, 1973;Whitfield and Blaber 1979), mammals (Taylor, 1980;Whitfield and Blaber, 1980), episodic events (Grindley and Heydorn, 1970;Blaber and Whitfield, 1976;Forbes and Cyrus, 1992;Martin et al, 1992), ecosystem functioning (Day et al, 1954;Millard and Broekhuysen, 1970;…”

Section: Introductionmentioning

confidence: 96%

A review of the importance of freshwater inflow to the future conservation of Lake St Lucia

Whitfield

Taylor²

2009

Aquatic Conservation

101

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ABSTRACT1. Lake St Lucia, the oldest formally protected estuary in the world is under threat from historic and present manipulation of freshwater supplies to the system.2. Constraints to the functioning of the ecosystem began in 1914 with the commencement of draining and canalization of the Mfolozi Swamp to open up the swamp and river floodplain for sugar cane cultivation. Warner's Drain was completed in 1936 and the sediment filtering capability of the swamp on river floodwaters was effectively removed. This resulted in exceptionally high sediment loads from the Mfolozi River entering directly into the St Lucia system and the river was therefore diverted southwards and provided with a separate estuary mouth. This deprived St Lucia of its single largest freshwater supply.3. During the past 50-60 years, increasing freshwater abstractions from the Mkhuze, Mzinene, Hluhluwe and Nyalazi rivers have contributed to the increasingly severe salinity extremes experienced by Lake St Lucia. In the past decade, desiccation of large areas of False Bay, North and South Lake has occurred, due primarily to natural estuary mouth closure combined with a prolonged drought and unnaturally low freshwater inflows during the closed phase. These events have pushed the system into an extreme state that has not been recorded previously and would not have occurred if Mfolozi River water had been available to the St Lucia system over this drought period.4. Forestry plantations have further exacerbated the freshwater supply situation, although recent removal of pine plantations on the eastern and western shores of the lake are likely to help restore groundwater flows to the system. 5. This review explores the possibility of relinking the Mfolozi River, once the Mfolozi floodplain swamp has been re-established, to the St Lucia system, thereby bringing urgently needed fresh water to this threatened World Heritage Site.

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Section: Introductionmentioning

confidence: 96%

A review of the importance of freshwater inflow to the future conservation of Lake St Lucia

Whitfield

Taylor²

2009

Aquatic Conservation

101

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“…Joubert and Davies 1966;Wallace and van der Elst 1975;Hill 1979;Bickerton 1989). Currently, this estuarine lake system supports a diverse array of marine, estuarine and freshwater fish species and the extremely wide salinity fluctuations (0-120 &) offer unique opportunities to study the impact of short-and long-term salinity changes on the ichthyofauna Martin et al 1992) as well as other components of the aquatic biota (e.g. Millard and Broekhuysen 1970;Boltt 1975;Blaber et al 1983;Martin et al 1992;Forbes and Cyrus 1993;Owen and Forbes 1997).…”

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confidence: 99%

Fishes and salinities in the St Lucia estuarine system—a review

Whitfield

Taylor²,

Fox³

et al. 2006

Rev Fish Biol Fisheries

117

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“…() found that after episodic river flooding, G. aestuaria was absent from beam‐trawl catches. Once flood waters have dissipated however and zooplankton stocks recovered, G. aestuaria abundance shows a positive response to flooding events (Martin et al, ). Likewise, Costa et al .…”

Section: Discussionmentioning

confidence: 99%

River flow, zooplankton and dominant zooplanktivorous fish dynamics in a warm‐temperate South African estuary

Mbandzi

Wasserman

Deyzel

et al. 2018

Journal of Fish Biology

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The possible links between river flow, zooplankton abundance and the responses of zooplanktivorous fishes to physico-chemical and food resource changes are assessed. To this end, the seasonal abundance, distribution and diet of the estuarine round-herring Gilchristella aestuaria and Cape silverside Atherina breviceps were studied in the Kariega Estuary. Spatio-temporal differences were determined for selected physico-chemical variables, zooplankton abundance and zooplanktivorous fish abundance and distribution. Results indicated that, following a river flood event in winter (>30 m s ), altered physico-chemical conditions occurred throughout the estuary and depressed zooplankton stocks. Abundance of G. aestuaria was highest in spring, with this species dominant in the upper and middle zones of the estuary, while A. breviceps was dominant in summer and preferred the middle and lower zones. The catch per unit of effort of both zooplanktivores also declined significantly following the flooding, thus suggesting that these fishes are reliant on zooplankton as a primary food source for healthy populations. Copepods dominated the stomach contents of both fish species, indicating a potential for strong interspecific competition for food, particularly in the middle reaches. Temporal differences were evident in dietary overlap between the two zooplanktivorous fish species and were correlated with river flow, zooplankton availability and fish distribution. The findings of this study emphasize the close trophic linkages between zooplankton and zooplanktivorous fishes under changing estuarine environmental conditions, particularly river flow and provide important baseline information for similar studies elsewhere in South Africa and the rest of the world.

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Episodic events: The effects of cyclonic flushing on the ichthyoplankton of St Lucia estuary on the southeast coast of Africa

Cited by 48 publications

References 7 publications

A review of the importance of freshwater inflow to the future conservation of Lake St Lucia

A review of the importance of freshwater inflow to the future conservation of Lake St Lucia

Fishes and salinities in the St Lucia estuarine system—a review

River flow, zooplankton and dominant zooplanktivorous fish dynamics in a warm‐temperate South African estuary

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