Short‐Term Thermal Effects of a Power‐Generating Plant on Zooplankton in the Swartkops Estuary, South Africa

Perissinotto, Renzo; Wooldridge, T.

doi:10.1111/j.1439-0485.1989.tb00473.x

Cited by 23 publications

(5 citation statements)

References 30 publications

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“…In the laboratory, samples were suspended in 1–5 L solutions, depending on the density of organisms. The main sample was then stirred vigorously so that all the organisms remained in a homogenous suspension and a 20 mL plastic vial attached to a metal rod was used to withdraw 3 subsamples from mid-depth [18] , [19] . Zooplankton within the samples was identified and counted with a dissecting microscope (×400) and density was calculated as ind.m −3 .…”

Section: Methodsmentioning

confidence: 99%

Development of a Halotolerant Community in the St. Lucia Estuary (South Africa) during a Hypersaline Phase

Carrasco

Perissinotto

2012

PLoS ONE

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BackgroundThe St. Lucia Estuary, Africa's largest estuarine lake, is currently experiencing unprecedented freshwater deprivation which has resulted in a northward gradient of drought effects, with hypersaline conditions in its northern lakes.Methodology/Principal FindingsThis study documents the changes that occurred in the biotic communities at False Bay from May 2010 to June 2011, in order to better understand ecosystem functioning in hypersaline habitats. Few zooplankton taxa were able to withstand the harsh environmental conditions during 2010. These were the flatworm Macrostomum sp., the harpacticoid copepod Cletocamptus confluens, the cyclopoid copepod Apocyclops cf. dengizicus and the ciliate Fabrea cf. salina. In addition to their exceptional salinity tolerance, they were involved in a remarkably simple food web. In June 2009, a bloom of an orange-pigmented cyanobacterium (Cyanothece sp.) was recorded in False Bay and persisted uninterruptedly for 18 months. Stable isotope analysis suggests that this cyanobacterium was the main prey item of F. cf. salina. This ciliate was then consumed by A. cf. dengizicus, which in turn was presumably consumed by flamingos as they flocked in the area when the copepods attained swarming densities. On the shore, cyanobacteria mats contributed to a population explosion of the staphylinid beetle Bledius pilicollis. Although zooplankton disappeared once salinities exceeded 130, many taxa are capable of producing spores or resting cysts to bridge harsh periods. The hypersaline community was disrupted by heavy summer rains in 2011, which alleviated drought conditions and resulted in a sharp increase in zooplankton stock and diversity.Conclusions/SignificanceDespite the current freshwater deprivation crisis, the False Bay region has shown to be resilient, harboring a unique biodiversity with species that are capable of enduring harsh environmental conditions. However, further freshwater deprivation may extend beyond the physiological thresholds of this community, as well as other unique biodiversity components which this system sustains.

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Section: Methodsmentioning

confidence: 99%

Development of a Halotolerant Community in the St. Lucia Estuary (South Africa) during a Hypersaline Phase

Carrasco

Perissinotto

2012

PLoS ONE

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“…The main sample was then stirred vigorously so that all the organisms remained in a homogenous suspension. A 20 ml plastic vial attached to a metal rod was then used to withdraw 3 to 6 subsamples from mid-depth (Perissinotto & Wooldridge 1989, Jerling & Wooldridge 1995. Zooplankton within the samples were identified and counted with a dissecting microscope (400 ×).…”

Section: Methodsmentioning

confidence: 99%

Zooplankton of the St. Lucia Estuary during the current drought cycle: a comparison between open- and closed-mouth conditions

Carrasco¹,

Perissinotto²,

Pillay³

2010

Mar. Ecol. Prog. Ser.

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“…The main sample was then stirred vigorously so that all the organisms remained in a homogenous suspension. A 20 mL plastic vial attached to a metal rod was then used to withdraw three subsamples from mid-depth (Perissinotto and Wooldridge 1989, Carrasco et al 2010). Individuals of Nitocra taylori sp.…”

Section: Methodsmentioning

confidence: 99%

A new species of Nitocra Boeck 1865 (Harpacticoida, Ameiridae, Ameirinae) from South Africa, with notes on its ecology and remarks on the status of Nitocra sewelli husmanni Kunz 1976

Gómez

Carrasco

Morales-Serna

2012

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A new species of the genus Nitocra Boeck, 1865, Nitocra taylori sp. n. is described from the St Lucia Estuary, Africa’s largest estuarine lake. It is also suggested that Nitocra sewelli husmanni Kunz, 1976 and Nitocra reducta fluviatilisGalhano, 1968 are granted full species rank as Nitocra husmanni stat. n. Kunz, 1976 and Nitocra fluviatilis stat. n. Galhano, 1968. Nitocra taylori sp. n. appears to be closely related to Nitocra husmanni. Unfortunately, the original description of the micro-characters of the species lacks the detail needed to make reliable comparisons between species of the genus Nitocra. The main differences observed are the number of spinules along the posterior margin of the anal operculum, length ratio of the exopod and endopod of the first swimming leg, shape of the outer spine on the male third endopodal segment of the third swimming leg, number of segments of the male antennule, relative length of the setae on the male baseoendopod of the fifth leg, shape of the male exopod of the fifth leg, relative length of the two setae of the male sixth leg, and shape of the female baseoendopod of the fifth leg. The current distribution of Nitocra taylori sp. n. is limited to the lake part of the estuary, an area which is most severely affected by the current freshwater deprivation crisis. During closed mouth conditions, these regions (South/North Lake and False Bay) are characterized by low water levels, high salinities and high turbidity levels. This suggests that Nitocra taylori sp. n. may favor these environmental conditions and the significant correlations found between the abundance of Nitocra taylori sp. n. and salinity and turbidity confirm this to a degree. Nitocra taylori sp. n. individuals are also able to withstand a wide range of fluctuations. They were recorded at turbidities ranging from 2 to 102 NTU, temperatures from 20.9 to 34.8 ºC and salinity levels ranging from 9.81 to 53.7 psu. However, in the current state of the system, salinity and temperature levels in the northern regions frequently exceed this value. Continued freshwater deprivation may, therefore, further limit the distribution range of this species.

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Short‐Term Thermal Effects of a Power‐Generating Plant on Zooplankton in the Swartkops Estuary, South Africa

Cited by 23 publications

References 30 publications

Development of a Halotolerant Community in the St. Lucia Estuary (South Africa) during a Hypersaline Phase

Development of a Halotolerant Community in the St. Lucia Estuary (South Africa) during a Hypersaline Phase

Zooplankton of the St. Lucia Estuary during the current drought cycle: a comparison between open- and closed-mouth conditions

A new species of Nitocra Boeck 1865 (Harpacticoida, Ameiridae, Ameirinae) from South Africa, with notes on its ecology and remarks on the status of Nitocra sewelli husmanni Kunz 1976

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