Effects of silt loading on the feeding and mortality of the mysid Mesopodopsis africana in the St. Lucia Estuary, South Africa

Carrasco, Nicola K.; Perissinotto, Renzo; Miranda, Nelson A.F.

doi:10.1016/j.jembe.2007.07.006

Cited by 25 publications

(29 citation statements)

References 38 publications

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“…Due to their different spatial distributions, strong freshwater inflows led to an increased N. integer density within the study stretch (downstream drift), whereas M. slabberi population was partially flushed out of the estuary by downstream currents (early autumn of 2003 in Figure 2n). Furthermore, as previously found for Mesopodopsis africana (Carrasco et al 2007), high IM seemed to have a negative effect on the M. slabberi density (Table 3), particularly evident during spring/summer 2008 (Figure 2n). This supports the hypothesis that a high IM concentration could reduce the health of mysids and their prey.…”

Section: Freshwater Inputs As Physical Forcing Of the Estuarine Envirsupporting

confidence: 81%

Effects of freshwater inputs on the lower trophic levels of a temperate estuary: physical, physiological or trophic forcing?

González‐Ortegón

Drake

2011

Aquat Sci

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The aim of this six year study was to assess whether freshwater inputs (rainfall and dam discharges) were acting as physical, physiological or trophic forcing factors on phytoplankton pigment concentrations and the dominant mysids of a temperate estuary (Guadalquivir estuary; SW, Spain). The effects of natural and human-controlled freshwater inputs modified the physicochemical conditions and consequently biological production (bottom up control). Nutrient (nitrogen hypernutrification), suspended particulate matter and allochthonous photosynthetic pigment importations linked to freshwater inputs from adjacent habitats were observed, as well as light-limited autochthonous primary production. Seasonal and/or spatial patterns were shown by all studied variables, including mysid species. Freshwater management effects on dominant mysids differed depending on the species' salinity tolerances (physiological forcing) and preferred prey availability (trophic forcing); moreover high inorganic matter content had a negative effect on the density of Mesopodopsis slabberi (physical forcing), which led to an increased detritivory/herbivory ratio (Neomysis integer/M. slabberi ratio). In conclusion, freshwater input appeared to affect estuarine lower trophic levels via a combination of different forcing mechanisms. Although several general patterns can be derived, the response of the system to freshwater input was not always univocal.

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Section: Freshwater Inputs As Physical Forcing Of the Estuarine Envirsupporting

confidence: 81%

Effects of freshwater inputs on the lower trophic levels of a temperate estuary: physical, physiological or trophic forcing?

González‐Ortegón

Drake

2011

Aquat Sci

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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: 99%

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

Whitfield

Taylor²

2009

Aquatic Conservation

103

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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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“…Following this, lake bed desiccation and hypersalinity became prominent features during dry phases (Carrasco et al, 2007;Jerling et al, 2010 and references therein). The services previously provided by the estuary became degraded, species were lost and the integrity of the estuary has since become compromised Cyrus et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

“…However, in the early 1900s, expanding agricultural practices along the Mfolozi floodplains resulted in the degradation of the filtering services provided by these swamps (Carrasco and Perissinotto, 2011;Whitfield et al, 2013). As a result, much of the fine sediment originally trapped in the swamps washed into the St Lucia Estuary, drastically increasing the sediment load and turbidity within the estuary (Carrasco et al, 2007;Nhleko et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Turbidity effects on the feeding, respiration and mortality of the copepod Pseudodiaptomus stuhlmanni in the St Lucia Estuary, South Africa

Jones

Carrasco

Perissinotto

2015

Journal of Experimental Marine Biology and Ecology

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Effects of silt loading on the feeding and mortality of the mysid Mesopodopsis africana in the St. Lucia Estuary, South Africa

Cited by 25 publications

References 38 publications

Effects of freshwater inputs on the lower trophic levels of a temperate estuary: physical, physiological or trophic forcing?

Effects of freshwater inputs on the lower trophic levels of a temperate estuary: physical, physiological or trophic forcing?

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

Turbidity effects on the feeding, respiration and mortality of the copepod Pseudodiaptomus stuhlmanni in the St Lucia Estuary, South Africa

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