Paleolimnology of a coastal lake on the Southern Cape coast of South Africa: Sediment geochemistry and diatom distribution

Gordon, N.; García-Rodríguez, Felipe; Adams, Janine B.

doi:10.1016/j.jafrearsci.2012.06.008

Cited by 11 publications

(10 citation statements)

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“…1300 CE, but the timing does correspond to the onset of more pronounced and variable hurricane activity compared to more subdued activity during the MCA. The inverse relationship between aquatic production and salinity over the past ~700 years is consistent with several studies of coastal lagoons that conclude elevated production during wetter years is likely due to enhanced nutrient-rich runoff from the surrounding catchment (García-Rodríguez et al, 2010; Gordon et al, 2012; Inda et al, 2006; Velez et al, 2018).…”

Section: Discussionsupporting

confidence: 88%

“…We also note that drought-related changes including desiccation, high pH and sediment carbonates are all associated with poor preservation (Flower, 1993; Flower and Ryves, 2009; Flower et al, 2006) and may explain the low abundances in these intervals. In a paleolimnological study of a South African coastal lagoon, poor preservation of diatoms in a section of the sediment core was associated with inferred high alkalinity and dry conditions with reduced water levels (Gordon et al, 2012). However, we recorded no obvious signs of diatom valve dissolution either within or bookending these zones of low abundance.…”

Section: Discussionmentioning

confidence: 99%

“…In coastal lagoons, precipitation can also exert a dominant control on aquatic production (Anthony et al, 2009), although this relationship is often complex. For example, several studies have documented a direct relationship between production and precipitation due to increases in freshwater runoff delivering nutrients and terrestrial organic matter (Velez et al, 2018; Gordon et al, 2012; García-Rodríguez et al, 2010). Conversely, other studies have documented increased production during drought conditions explained by lower-than-normal water levels making it easier for wind to resuspend sediments and release nutrients from the lake bottom (Niemisto et al, 2008; Søndergaard et al, 1992).…”

Section: Discussionmentioning

confidence: 99%

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The response of diatom assemblages in a Jamaican coastal lagoon to hurricane and drought activity over the past millennium

et al. 2021

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Reconstructing pre-industrial hurricane activity and aridity from natural archives places modern trends within the context of long-term natural variability. The first reconstruction of Atlantic hurricane activity in Jamaica was based on a sediment record previously obtained from a coastal lagoon. Specifically, an Extended Hurricane Activity (EHA) index was developed from high-resolution geochemical data that linked fluctuations in lake-level changes to rainfall variability associated with hurricane activity. Here, we analyse the same sediment core from which the EHA index was developed to assess the response of biological indicators, namely fossil diatom assemblages and sediment chlorophyll a (chl- a) concentrations, to hydrometeorological events (tropical cyclone-induced precipitation and droughts) over the past ~1500 years. The diatom assemblages responded sensitively to changes in salinity associated with lake-level changes driven by the balance of precipitation and evaporation. Aquatic production (inferred from sediment chl- a, which includes its main diagenetic products) and salinity (inferred from ITRAXTM µXRF chlorine counts) vary inversely following ca. 1300 CE, likely due to enhanced nutrient delivery from freshwater runoff during periods of elevated precipitation. Although the temporal resolution of our biological data is less-well resolved than that of the geochemical record, it generally tracks long-term trends in rainfall variability inferred by the EHA index over the past millennium. This further demonstrates the potential of using biological proxies from coastal lagoons to track past hurricane activity and aridity.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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The response of diatom assemblages in a Jamaican coastal lagoon to hurricane and drought activity over the past millennium

et al. 2021

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“…The area is considered a biodiversity hotspot because of the unique animals, ora and landscapes found in the region. It is a home to a highly threatened lowland fynbos type of vegetation and a prominent area for twitches (Gordon et al 2012). The indigenous fauna and ora of the region form the basis of the shing and tourism sectors of the economy (Gordon et al 2011).…”

Section: Description Of the Study Areamentioning

confidence: 99%

Use of remotely sensed derived metrics to assess wetland vegetation responses to climate variability-induced drought at the Soetendalsvlei wetland system in the Heuningnes Catchment, Western Cape province, South Africa

Ndlala

Dube

2021

African Journal of Aquatic Science

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Wetland areas are the most vital ecosystems and they provide important functions towards stabilizing the environment. Hydrological processes in these wetland systems directly affects the productivity of plants. Therefore, assessing vegetation response to climate variability induced drought is vital in wetlands. In this paper, the subtle changes in vegetation distribution were used as a proxy to examine and quantify the extent of drought impacts on wetland ecosystems within the Heuningnes catchment, South Africa. First, vegetation health information was extracted by calculating the normalized difference vegetation index (NDVI) during the wet and dry seasons for the period between 2014 and 2018. The derived NDVI results were further statistical linked to the corresponding rainfall and evapotranspiration (ET) observed during the study period. An analysis of NDVI results revealed that gradual vegetation health change occurred across the study area. The highest derived NDVI (0.5) for wetland vegetation was observed during the year 2014 but progressively declined over the years. Change in vegetation health indicated a signi cant (α = 0.05) and positive correlation to the amount of rainfall received over the same period. The results of this study showed that healthy vegetation deteriorated between the study periods due to the 2015-2017 Western Cape drought.

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“…Sediments of coastal lakes provide an opportunity for palaeoecological research and were previously used to reconstruct the evolution of South Africa's coastal environments and its driving forces, that is, climate, sea level fluctuations and human impact (Baxter and Meadows 1999;Gordon et al 2012). Here, we present a sediment record from Eilandvlei, a coastal lake located in the Wilderness Embayment at the southern Cape coast (Fig.…”

Section: Introductionmentioning

confidence: 99%

A 700‐year record on the effects of climate and human impact on the southern cape coast inferred from lake sediments of eilandvlei, wilderness embayment, south africa

Reinwarth

Franz

Baade

et al. 2013

Geografiska Annaler: Series A, Physical Geography

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The southern Cape coast, South Africa, is sensitive to climate fluctuations as it is influenced by different atmospheric and oceanic circulation systems. Palaeoecological evidence of Holocene climate variations in this region is presently limited. Here, we present a lake sediment record spanning approximately the last 670 years from Eilandvlei, a brackish coastal lake situated mid‐way between Cape Town and Port Elizabeth. The results from geochemical and sedimentological analyses point to an increase in minerogenic sediment input from the catchment starting around ad 1400. Changes in the seasonal distribution of rainfall during the Little Ice Age may have altered river discharge and increased erosion rates and fluvial sediment transport in pre‐colonial times. A rising mean lake level, possibly associated with an altered water balance or relative sea‐level rise, may offer an explanation for the deposition of finer sediments. After ad 1450, reduced burial flux of elements associated with autochthonous sediment formation may have resulted from ecological changes in Eilandvlei. Enhanced sedimentation rates, increasing carbon, nitrogen, phosphorous and biogenic silica concentrations, as well as high concentrations of proxies for allochthonous sediment input (e.g. aluminium, titanium, zirconium) point to increasing sediment and nutrient flux into Eilandvlei from the late nineteenth century onwards. The most likely factor involved in these recent changes is land‐use change and other forms of human impact.

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Paleolimnology of a coastal lake on the Southern Cape coast of South Africa: Sediment geochemistry and diatom distribution

Cited by 11 publications

References 54 publications

The response of diatom assemblages in a Jamaican coastal lagoon to hurricane and drought activity over the past millennium

The response of diatom assemblages in a Jamaican coastal lagoon to hurricane and drought activity over the past millennium

Use of remotely sensed derived metrics to assess wetland vegetation responses to climate variability-induced drought at the Soetendalsvlei wetland system in the Heuningnes Catchment, Western Cape province, South Africa

A 700‐year record on the effects of climate and human impact on the southern cape coast inferred from lake sediments of eilandvlei, wilderness embayment, south africa

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