Macrobenthic community structure of the Mhlathuze Estuary, a permanently open estuarine embayment in KwaZulu-Natal, South Africa

Izegaegbe, Joshua Idowu; Vivier, L; Mzimela, Hendrick Mduduzi

doi:10.2989/16085914.2020.1719818

Cited by 11 publications

(4 citation statements)

References 37 publications

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“…Variability in physical and biogeochemical process pathways creates a wide range of ecological niches and unique patterns of connectivity between them. This supports biodiversity (Sun et al, 2013;Sun et al, 2015), and many organisms have evolved life history traits tuned to the wide variations in physicochemical conditions (Sun et al, 2015;Zhang M. et al, 2017;Duggan et al, 2019;Izegaegbe et al, 2020).…”

Section: Key Estuarine Ecosystem Processesmentioning

confidence: 70%

“…Furthermore, these shifts can maintain a greater phytoplankton biodiversity and promote carbon and nutrient transport via phytoplankton (Ortmann et al, 2011). Large flow events (e.g., 10-year or 100-year floods) can benefit estuarine biodiversity, promoting high phytoplankton productivity as freshwater flows subside (Steichen et al, 2020), as well as favouring opportunistic microbenthic species over the incumbent dominant species (Izegaegbe et al, 2020). However, there are often adverse effects of large flow events on estuaries (Osburn et al, 2019;Hu et al, 2020), such as changes to geomorphology and salinity, which can cause stress to and mortality of organisms through increased flushing and osmotic stress (Park et al, 2014).…”

Section: Salinity Regulationmentioning

confidence: 99%

“…Modifications to the timing of flow delivery can have profound impacts on estuarine processes (Figure 4) with consequences for species which are adapted to these natural variations (Bunn et al, 2014;Cai et al, 2019;Izegaegbe et al, 2020). Modified seasonal flow patterns (#1 Figure 4) interact with temperature (#1a Figure 4) and the delivery of nutrients, organic matter and sediments (#1b Figure 4), to alter the hydrodynamics (#1c Figure 4), salinity (#1d Figure 4), resource availability (#1e Figure 4), predator-prey cycles and food web functioning (#1f Figure 4; Hallett et al, 2018;Hamilton et al, 2020).…”

Section: Changes To the Timing Of Flowsmentioning

confidence: 99%

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Environmental Flow Requirements of Estuaries: Providing Resilience to Current and Future Climate and Direct Anthropogenic Changes

Chilton

Hamilton

Nagelkerken

et al. 2021

Front. Environ. Sci.

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Estuaries host unique biodiversity and deliver a range of ecosystem services at the interface between catchment and the ocean. They are also among the most degraded ecosystems on Earth. Freshwater flow regimes drive ecological processes contributing to their biodiversity and economic value, but have been modified extensively in many systems by upstream water use. Knowledge of freshwater flow requirements for estuaries (environmental flows or E-flows) lags behind that of rivers and their floodplains. Generalising estuarine E-flows is further complicated by responses that appear to be specific to each system. Here we critically review the E-flow requirements of estuaries to 1) identify the key ecosystem processes (hydrodynamics, salinity regulation, sediment dynamics, nutrient cycling and trophic transfer, and connectivity) modulated by freshwater flow regimes, 2) identify key drivers (rainfall, runoff, temperature, sea level rise and direct anthropogenic) that generate changes to the magnitude, quality and timing of flows, and 3) propose mitigation strategies (e.g., modification of dam operations and habitat restoration) to buffer against the risks of altered freshwater flows and build resilience to direct and indirect anthropogenic disturbances. These strategies support re-establishment of the natural characteristics of freshwater flow regimes which are foundational to healthy estuarine ecosystems.

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Section: Key Estuarine Ecosystem Processesmentioning

confidence: 70%

Section: Salinity Regulationmentioning

confidence: 99%

Section: Changes To the Timing Of Flowsmentioning

confidence: 99%

See 1 more Smart Citation

Environmental Flow Requirements of Estuaries: Providing Resilience to Current and Future Climate and Direct Anthropogenic Changes

Chilton

Hamilton

Nagelkerken

et al. 2021

Front. Environ. Sci.

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“…As caracterís� cas naturais dos ambientes estuarinos tornam esses ecossistemas ainda mais complexos do ponto de vista ecológico (Sun et al, 2015;Zhang M. et al, 2017;Duggan et al, 2019;Izegaegbe et al, 2020). Suas águas geomorfologicamente protegidas com baixos fl uxos hidrodinâmicos e troca de água restrita com o mar adjacente resultam em níveis mais baixos de oxigênio na coluna d'água, o que favorece a concentração de contaminantes em seu sedimento, composto de par� culas de granulação fi na e altos níveis de matéria orgânica (Guerra-García e García-Góme 2004).…”

Section: Introductionunclassified

Extração sequencial BCR para frações geoquímicas e avaliação de Zn, Ni, Cd, Cu e Pb nos sedimentos costeiros no Complexo Portuário de Santos, Sudeste do Brasil

Delgado

Lima

Vieira

et al. 2023

S&G

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As variações da coluna d'água no ambiente aquático, motivadas por processos naturais ou antropogênicos, podem afetar a estabilidade de metais-traço no sedimento do Complexo Portuário de Santos (CPS), localizado no sudeste do Brasil. Metais-traço, como Cu, Zn, Ni, Pb e Cd, podem afetar negativamente os compartimentos ecológicos e biológicos da água estuarina. Para avaliar a condição do sedimento do CPS, este artigo investigou a fração geoquímica de metais-traço sedimentares aplicando a abordagem de extração sequencial BCR (European Community Bureau of Reference - Gabinete de Referência da Comunidade Europeia). A matéria orgânica e o tamanho de grão fino, característicos de um ambiente estuarino, mostraram uma influência direta na dinâmica de concentração de metais-traço em sedimentos, especialmente para Pb, Cd e Ni. No caso específico de Zn e Cu, havia uma possível fonte de contaminação no porto. A maior fração dos metais estudados era não residual, potencialmente mobilizável em um ambiente em que a variação dos parâmetros físico-químicos da coluna d'água é altamente variável, algo frequente em ambientes estuarinos. Palavras-chave: especiação de metais-traço; Porto de Santos; sedimento; impacto ambiental.

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Trace metal contamination in sediment in the Mhlathuze Estuary, northern KwaZulu-Natal, South Africa: effects on the macrobenthic community

Izegaegbe

Vivier

Mzimela

2020

Environ Monit Assess

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Mhlathuze Estuary constitutes one of the ecological most important estuaries in southern Africa and is regarded as an estuary of high conservation importance. The ongoing expansion of the adjacent industrialized Richards Bay Harbour increases the risk of metal pollution to the estuary. This study provides insight into the extent and sources of trace metal contamination using pollution indices and sediment quality guidelines and the effect on macrobenthic habitat quality. Sediment samples for sediment metal and macrobenthic analysis were collected quarterly during 2016-2017 at five sites in the estuary using a marine-grade Zabalocki grab. Metal concentrations were determined using an ICP-OES. Sediment metal concentrations were consistently highest in the subtidal mudflats and lowest in marine sand at the mouth of the estuary. Concentrations of all metals displayed significant differences between sites (P < 0.05). Pollution indices indicated moderate enrichment of Cr at all sites, although the mean pollution load index showed the estuary to be unpolluted. Comparison with sediment quality guidelines revealed that concentrations of Ni and Cr were potentially toxic to biota. Using multivariate analysis, metal concentrations appeared not to significantly affect the macrobenthic community. The multi-metric biotic index M-AMBI proved to be a robust tool in the habitat quality assessment of the estuary. The continuing use of M-AMBI as a biomonitoring tool for ecological management of the estuary is advocated.

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Macrobenthic community structure of the Mhlathuze Estuary, a permanently open estuarine embayment in KwaZulu-Natal, South Africa

Cited by 11 publications

References 37 publications

Environmental Flow Requirements of Estuaries: Providing Resilience to Current and Future Climate and Direct Anthropogenic Changes

Environmental Flow Requirements of Estuaries: Providing Resilience to Current and Future Climate and Direct Anthropogenic Changes

Extração sequencial BCR para frações geoquímicas e avaliação de Zn, Ni, Cd, Cu e Pb nos sedimentos costeiros no Complexo Portuário de Santos, Sudeste do Brasil

Trace metal contamination in sediment in the Mhlathuze Estuary, northern KwaZulu-Natal, South Africa: effects on the macrobenthic community

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