S. Pillay1;3, Dr. A. J. Smit2, Dr D. Robertson-Andersson1;3

1UKZN2UWC

3MACE Lab

Introduction

Main Aim

The aim of this study was to investigate the level and extent of N pollution to the south coast of KZN

ObjectivesThe specific objectives were:

(1) To determine if each estuary chosen for this study is eutrophic and comparisons made with the current known health status

(2) To determine the effect of season on nitrogen pollution in rocky shores during the closed and open phase of the estuary

(3) To determine if the level of nitrogen pollution changes with increasing distance away from the estuary.

HypothesesIt was hypothesised that :

(1) There is a difference in N pollution among the three sites (Hibberdene, Margate and Port Edward).

(2) Rocky shore habitats are supplemented by nutrients from estuarine sources

Study designChoosing estuaries

Health state of estuary Description

Excellent Estuaries with high water quality, level of habitat

integrity are high, high diversity and high provision of

goods and services.

Good Estuaries with most of the core estuarine habitat and

estuarine support habitats still present, good water

quality, diversity of habitats and species and estuarine

processes in place.

Fair Estuaries with core estuarine habitat intact, some

estuarine support habitats, impacted water quality and

some loss of diversity and key estuarine process in

place.

Poor Estuaries with impacted core estuarine habitat.

Substantially reduced or no estuarine support habitats,

polluted water, substantial loss of diversity and/or

abundance and key estuarine processes impaired.

Highly degraded Estuaries which have had major impacts on core

estuarine habitats through infilling, canalisation and

pollution, substantially reduced or no estuarine support

habitats and major loss of key estuarine processes.

Table 1. Ranking of esturine state based on functionng and health of the system (adapted from Forbes & Demetriades(2008))

Mhlungwa(Hibberdene)

Kongweni(Margate)

Mtamvuna(Port Edward)

Study sites

Figure 1. Map of sites chosen for study

HibberdeneHibberdene(Mhlungwa Estuary)

Margate (Kongweni Estuary with WWTP)

Port Edward (Umtamvuna Estuary)

Hibberdene(Mhlungwa Estuary)

Margate (Kongweni Estuary with WWTP)

Port Edward (Umtamvuna Estuary)

Sampling

Mouth:POMDINδ15N (POM)Chl a

100 m

200 m

1000 m

2000 m

δ15N of Macroalgae

Figure 2. sampling plan for each site

600 m

Nutrient analysis

Filtered samples were analysed for nitrate and phosphate using SKALAR SAN ++ nutrient analyser

POM

Filtrate collected on pre-combusted GFF filters were used for POM

Isotope analysis

Macroalgae Jania intermedia and Hypnea spicifera

www.mpcer.nau.eduTaken by: Shivanee Pillay

Statistical analyses Analysis of Covariance (ANCOVA).

ANOVA

Results

Estuary

Figure 2 Level of nutrient pollution in each of the estuaries in Hibberdene (Mhlungwa), Margate (Kongweni) and Port Edward (Umtamvuna)

Rocky Shores

Figure 5. 2 Level of nitrogen pollution distributed across stations in Hibberdene(Mhlungwa), Margate (Kongweni) and Port Edward (Umtamvuna)

Overall outcomes and recommendations Nitrogen pollution is evident among the sites concerned

It is suggested that both the estuary and rocky shore habitat be monitored to elucidate other factors not considered here.

The condition of sites chosen for this study clearly indicate a need for mitigation of nutrient pollution in estuaries and a greater need for development of WWTW along the coast of KZN.

A survey of the KZN coastline will give an indication of those similarly impacted and in need of mitigation

Thank you

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