Water quality and ecological integrity of estuaries reflect activities within the entire upstream catchment. Much emphasis has been placed on the response of estuaries to anthropogenic stressors through the use of monitoring programmes. Key to the success of these programmes is the use of indicators as they transform data into useful information. The ultimate aim of this study was to identify eutrophic symptoms in selected estuaries in the Gouritz Water Management Area (WMA) using a multi-metric classification method. The study sites included the permanently open Duiwenhoks, Goukou, Gouritz, and Kaaimans estuaries, as well as the temporarily open/closed Hartenbos, Klein Brak, Great Brak, Gwaing, and Goukamma estuaries. Initially, the “pressure” associated with all the estuaries in the Gouritz WMA was determined (e.g. total daily nutrient loads and changes in river inflow affecting flushing time) using long-term flow and water quality monitoring data provided by the Department of Water Affairs (DWA). Subsequently, the “state” of the selected estuaries was assessed using a variety of indicators, including: inorganic nutrients (~ N and P), phytoplankton, epiphytes and microphytobenthos. Estuaries with longer flushing time suggested greater vulnerability to eutrophication. For example, the Gwaing (281.11 kg DIN d-1; 78.85 kg DIP d-1) and Hartenbos (38.33 kg DIN d-1; 21.51 kg DIP d-1) estuaries generally received the highest daily inorganic nutrient loads. However, at the time of sampling, the Hartenbos Estuary had a longer flushing time (i.e. weeks) compared to the Gwaing Estuary (i.e. couple of days). Field data confirmed the greater vulnerability to eutrophication associated with longer flushing times, as the indicators measured in the Hartenbos Estuary exceeded all the proposed ‘thresholds’ of a eutrophic system (~ overall ‘Poor’ condition). The Great Brak Estuary (~ overall ‘Fair’ condition) provided an interesting example where eutrophic symptoms were only detected when assessing the microalgal primary producers (i.e. high biomass and low diversity). Furthermore, the need to distinguish between naturally and anthropogenically induced symptoms was highlighted. One such scenario was noted in the Kaaimans Estuary, where its natural hydro-morphological characteristics (i.e. steep banks, low river inflow, and deep/narrow channel) led to the possible exaggeration of its overall eutrophic condition, i.e. received a ‘Fair’ rather than ‘Good’ rating, arising from ‘Poor’ ratings for dissolved oxygen and benthic diatom diversity. Overall, this study demonstrated the importance of adopting a holistic approach when assessing the condition and trophic status of estuaries. Studies such as these allow for the detection of vulnerable and degraded systems, which can provide important information with regards to the identification of management priorities.

Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: The primary aim of this study was to assess and compare the ecological integrity of the Lourens, Palmiet and Hout Bay Rivers (South Western Cape, South Africa) by examining the macroinvertebrate community structure at a series of representative sampling sites along the course of each river, using the South African Scoring System - Version 5 (SASS-5) rapid bioassessment method. Secondary aims included an examination of the effects of seasonal variability, biotope availability and site-specific environmental variables on the macroinvertebrate community structure at sampling sites, as well as the preliminary testing of the Integrated Habitat Assessment System (IHAS) for aquatic macroinvertebrates. According to results obtained, the ecological integrity of sampling sites in the Mountain Stream Zone of the three rivers was consistently good. The Hout Bay River in the upper portions of the Orange Kloof Reserve was particularly near-pristine, with this area having been identified in this study as a potential biodiversity ‘hot-spot’ for aquatic macroinvertebrates. Downstream of the Mountain Stream Zone, there was a significant deterioration in the ecological integrity of all three rivers due to a number of probable causes. Results based on recorded SASS Scores and Average Score per Taxon (ASPT) values, using ‘biological bands’ generated from reference sites in the South Western Cape, were generally similar to and supported by the corresponding multivariate analyses undertaken. From the results of the various analyses undertaken in this investigation and some of the problems encountered in interpreting the data, a number of recommendations are made regarding future bioassessment studies based on the SASS within the national River Health Programme (RHP). To test the IHAS, secondary data were obtained from reference sites in the Mpumalanga and Western Cape Provinces of South Africa. Assuming that SASS Scores at reference sites are the highest scores attainable, one would expect to find a positive relationship between SASS Scores and IHAS scores at reference sites. The assumption in this investigation was that this relationship should be linear. Non-parametric correlation analyses were undertaken between SASS-4/5 Scores and IHAS scores, using Kendall’s Rank-correlation Coefficient (τ), with separate analyses undertaken for different geomorphological zones and biotope groups. Correlations between SASS Scores and IHAS scores were generally weak (τ-values mostly < 0.3) and unsatisfactory, with no significant correlations (p < 0.05) for two-thirds of the data sets analysed and a wide degree of scatter generally observed amongst data points in respective scatter plots. The performance of the IHAS varied between geomorphological zones and biotope groups, with the Foothill: Gravel-bed Zone in Mpumalanga showing the best results, particularly when the stones-in-current biotope group was analysed separately. Further testing of the IHAS is required to confirm its relative performance in different bioregions/ecoregions, geomorphological zones and biotope groups, which should be undertaken as a priority research area within the RHP. Unsuccessful attempts to test the IHAS by means of multiple regression analyses were undertaken, suggesting that such techniques should be avoided in further testing of the IHAS. / AFRIKAANSE OPSOMMING: Die hoofdoel van hierdie studie was om die ekologiese toestand van die Lourens-, Palmiet- en Houtbaairiviere (Suidwes Kaap, Suid Afrika) te bepaal en te vergelyk deur die bestudering van die makroinvertebraatgemeenskapstruktuur by verteenwoordigende monsterpunte langs die riviere, met gebruik van die “South African Scoring System” – Weergawe 5 (SASS-5) snelle biologiese bepalingsmetode. Sekondêre doelwitte het die bepaling van die gevolge van seisoenele veranderlikheid, biotoop beskikbaarheid en ligging-bepaalde omgewingsveranderlikes op die makroinvertebraatgemeenskapstruktuur by monsterpunte ingesluit, asook die inleidende toetsing van die “Integrated Habitat Assessment System” (IHAS) vir watermakroinvertebrate. Volgens die resultate verkry, was die ekologiese toestand van monsterpunte in die Bergstroomsone van die drie riviere konsekwent goed. Die Houtbaairivier in die boonste gedeelte van die Oranjekloofreservaat was veral feitlik onversteurd en hierdie streek is in die studie as ‘n potensiaal biodiversiteit “hot-spot” vir watermakroinvertebrate geidentifiseer. Stroomafwaarts van die Bergstroomsone was daar ‘n beduidende verswakking in die ekologiese toestand van al drie riviere, as gevolg van ‘n aantal moontlike oorsake. Resultate gebaseer op bepaalde “SASS Scores” en ‘Gemiddelde Waarde per Takson’ (“Average Score per Taxon” - ASPT) waardes, met gebruik van ‘biologiese bande’ wat van verwysingsmonsterpunte in die Suidwes Kaap afgelei is, was oor die algemeen soortgelyk aan en gestaaf deur die ooreenstemmende multiveranderlikke (“multivariate”) statistiese analises wat gedoen is. Uit die resultate van die verskeie analises wat in hierdie ondersoek gedoen is en sommige van die probleme wat in die dataverklaring gevind is, is ‘n aantal aanbevelings gemaak met betrekking tot toekomende biologiese bepalingstudies vir die nasionale Riviergesondheidsprogram (“River Health Programme” - RHP) wat op die SASS gebaseer is. Om die IHAS te toets is sekondêre data van verwysingsmonsterpunte in die Mpumalanga en Wes Kaap Provinsies van Suid Afrika verkry. As aangeneem word dat die “SASS Scores” by verwysingsmonsterpunte die hoogste moontlike tellings is wat bereik kan word, sou ‘n positiewe verwantskap tussen “SASS Scores” en IHAS tellings by verwysingsmonsterpunte verwag word. Die veronderstelling in hierdie studie was dat dié verwantskap lineêr moet wees. Nie-parametriese korrelasieanalise tussen “SASS-4/5 Scores” en IHAS tellings is gemaak, deur gebruik van Kendall se Rangkorrelasiekoëffisiënt (τ), met afsonderlike analises vir verskillende geomorfologiese sones en biotoopgroepe verrig. Korrelasies tussen “SASS Scores” en IHAS tellings was algemeen swak (τ-waardes < 0.3) en onbevredigend, met geen beduidende korrelasies (“p” < 0.05) vir twee-derdes van die datastelle wat geanaliseer is nie en ‘n wye verspreiding tussen datapunte in die onderskeie “scatter plots” wat waargeneem is. Die funksionering van die IHAS was verskillend tussen geomorfologiese sones en biotoopgroepe. Die beste resultate is vir die Voorheuwel: Gruisbeddingsone in Mpumalanga verkry, veral indien die klippe-in-stroom biotoopgroep afsonderlik geanaliseer is. Verdere toetsing van die IHAS is nodig om die relatiewe funksionering in verskillende biostreke/”ecoregions”, geomorfologiese sones en biotoopgroepe te bevestig en dit behoort voorangs te geniet binne die RHP. Pogings om die IHAS deur middel van veelvoudige regressie analise te toets het misluk, wat aandui dat sulke tegnieke vermy moet word in verder toetsing van die IHAS.

Lower reaches of rivers as well as estuaries are regarded as South Africa’s most productive ecosystems due to the important functions such as providing nursery areas and feeding sites for juvenile macro-invertebrate and fish species they perform. Furthermore, ecologically healthy estuaries are not only of critical importance since they facilitate the provision and recirculation of nutrients, they also provide conduits for fish migrations into the fresh water system and act as buffers during floods. In South Africa, these functions are continuously being threatened by residential and/or industrial developments. It is thus essential to determine the ecological integrity (structure and function) of these systems. An Ecological integrity study was carried out on the selected rivers in Kwazulu Natal between 2015 and 2017. This study was assessed in terms of selected abiotic drivers on specific biological responses. The study was carried out according to the guidelines of the ecological determination methodologies and the resource directed measures for aquatic resources as set out by the Department of Water Affairs and Forestry, South Africa. Surveys were carried out during summer and winter seasons. Abiotic and biotic monitoring was carried out at four sites along each estuary. The abiotic component such as sediment composition and physio-chemical properties of the water was analyzed using standard methods. The biotic and abiotic components were analyzed using various indices, where applicable. The ecological integrity of the system can be accessed on the basis of its ability to carry out its natural functions. Results showed the various anthropogenic activities in the upper reaches of each river contributed to the high modified state of some of these rivers’ unacceptable water quality, loss and/or modification of habitat and an altered hydrological pattern due to impacts by agricultural, industrial and domestic uses. The ecosystem services of the lower areas of the rivers under investigation are used extensively through sugarcane agricultural activities and heavy industries works inclusive of sand mining and rural sewage-treatment. These activities affect the ecological integrity of the rivers and ultimately the estuaries. This study aimed at determining the current state of ecological integrity of five selected rivers in KwaZulu Natal and to establish trends between current and historical periods for the evaluation of changing trends in ecological integrity. Abiotic and biotic indicator components were used to ascertain changes in the surrounding environment as well as to determine the ecological integrity of these rivers. Monitoring of water quality, sediment grain size, moisture and organic content as well as habitat state, macro-invertebrates and fish assemblages was undertaken. The following variables water temperature, chemical oxygen demand (COD), electrical conductivity (EC), pH and total alkalinity (TAL) as well as salts, nutrients and toxics were investigated to provide indications as to the state of the water-quality of these rivers. The Target Water Quality Requirements (TWQR) as developed by the Department of Water Affairs and Forestry for domestic use (Volume 1) and Aquatic Ecosystems (Volume 7) were used to evaluate the quality of the water sampled in this study. Historical data obtained from previous studies of similar study areas have also been evaluated. Sediment analyses were performed according to the protocol set out by the United States Environmental Protection Agency. As a result of the abiotic drivers, results showed that the invertebrate reside in modified state. Physio-chemical, geomorphological and hydrological changes in this system resulted in the rivers’ suffering a loss in both biological and ecological function as well as aesthetic value. It is apparent from the above that there is not a need for rehabilitation but also a need for effective and continuous management strategies. These strategies can only be successful if the bio-monitoring of the system includes the effects at both economical and social levels. The water quality of the rivers under this investigation was found to be in a slightly modified state with the majority of water quality parameters falling within the target values. Water quality parameters of the lower Thukela River, not within the required target, was highly elevated and could possibly cause negative impacts on the river functionality. The water quality parameters of Umvoti river, Umdloti river and uMngeni river were seriously modified. The sediment clearly indicated that the organic content of the all the rivers was low and directly relating to the possibility of erosion and transportation taking place in the Rivers. The removal of riparian vegetation by agricultural activities, sand mining and water abstraction contributed to the destruction of the habitats along all these rivers. The South African Scoring System, version 5 (SASS 5), the Macro-invertebrate Response Assessment Index (MIRAI) and multivariate statistical analyses were implemented in order to determine the ecological integrity of the rivers. Results revealed that the SASS 5 integrity classes were generally one class higher than the integrity classes of MIRAI. The Fish assemblage methods used to determine fish samples included electro-narcosis and a 5m wide 12mm meshed seine net. Impacts on the ecological integrity of the Rivers under investigation have been assessed by various sources. To protect the current ecological integrity and further destruction of the rivers under investigation, direct involvement by the relevant authorities is of paramount importance. / Agriculture and Environmental Science / D. Litt. et Phil. (Environmental Science)

Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The River Health Programme (RHP) is an assessment tool for monitoring the ecological state of rivers to ensure that they remain fit for use by present and future generations. This study, forming part of a RHP assessment conducted on the south-western Cape Hout Bay, Lourens and Palmiet Rivers, has the aim to (1) zone the rivers for representative site selection, (2) assess their habitat integrity (HI), (3) determine the influence of land use on riverine HI and (4) assess the river water quality at the time of the RHP assessments. (1) The desktop geomorphological zonation method used in RHP assessments has not been sufficiently previously tested on short rivers draining the Western Cape Mountains. The Lowland River Zone of the rivers studied, as well as the Hout Bay River’s Upper Foothill Zone, were found to have steeper gradients than expected, probably due to these rivers being shorter and consequently steeper than any on which the method was previously tested. The notion of one gradient river classification system being applicable throughout South Africa, with its diverse geology and climate, is unlikely. Rather a classification system modified for various physiographic features regions or by a factor based on river length is more realistic. (2) Although there is a general longitudinal decrease in HI downstream along the Hout Bay and Lourens Rivers, coinciding with increased anthropogenic activities, HI improves in the Palmiet River’s lower reaches through the Kogelberg Nature Reserve. Surrounding land use thus seems to be a major determinant of HI. Although the Index of Habitat Integrity (IHI) used appears to achieve its aim, it was found to be subjective. Categorisation of the IHI scoring is suggested. (3) The amount of natural versus disturbed land use occurring upstream of a site at a regional and local scale, is a good predictor of riverine HI. Regional alien forestry and local urbanisation have significantly strong negative effects on instream (r2 = -0.80, r2 = 0.80, p<0.05) and riparian (r2 = -0.81, r2 = -0.83, p<0.05) HI. Different land use types therefore appear to affect riverine HI at differing scales and thus managers must not only think on a local but also a catchment scale. (4) In the Hout Bay River, a filtering system (e.g. wetland) appears to improve the water quality between the middle and lower reaches. Along the Lourens River, high total dissolved salts, conductivity and inorganic nitrogen concentrations in the middle reaches are cause for concern. Along the Palmiet River there appeared to be insufficient oxygen to support most aquatic life forms at Grabouw. Impoundments in the middle reaches act as sinks for nutrients and salts, but the Huis and Krom tributaries downstream then appear to degrade the water quality of the Palmiet River’s lower reaches within the Kogelberg Nature Reserve. Together with the results of simultaneous biotic assessments, these results should be used to develop management actions to improve the ecological health of these rivers. The results have been used in a State-of-Rivers Report for the south-western Cape. / AFRIKAANSE OPSOMMING: Die Riviergesondheidsprogram (RGP) is 'n asseseringsinstrument wat die ekologiese stand van riviere monitor om te verseker dat hulle steeds bruikbaar bly vir huidige en toekomstige geslagte. Hierdie studie maak deel uit van 'n RGP-assessering van die Lourens-, Houtbaai- en Palmietrivier in die Suidwes-Kaap en het ten doel om (1) die riviere te soneer vir verteenwoordigende terreinseleksie, (2) die habitat-integriteit (HI) te assesseer, (3) die invloed van grondgebruik op rivier-HI te bepaal en (4) die kwaliteit van rivierwater tydens die RGP-assesserings te bepaal. (1) Die geomorfologiese-soneringsmetode wat in RGP-assesserings gebruik word, is nog nie voorheen genoegsaam vir die kort riviere wat die Wes-Kaapse berge dreineer, getoets nie. Daar is bevind dat die studiegebied riviere in die laagland-sones skerper gradiënte het as verwag, gehad het. Dit kan moontlik toegeskryf word aan die riviere wat korter en dus steiler is as enige van dié wat voorheen met die metode getoets is. Die moontlikheid dat een gradiëntklassifikasiestelsel vir riviere regdeur Suid-Afrika met sy diverse geologie en klimaat toegepas kan word, is onwaarskynlik. 'n Klassifikasiestelsel aangepas vir verskillende fisiografiese streke of met 'n faktor gebaseer op rivierlengte, is meer realisties. (2) Alhoewel HI stroomaf langs die Lourens- en Houtbaairivier in die algemeen longitudinaal saam met die toename in antropogeniese aktiwiteite afneem, verbeter die Palmietrivier se HI waar dit laer af deur die Kogelbergnatuurreservaat vloei. Die gebruike van aanliggende grond blyk dus 'n belangrike bepaler van HI te wees. Die Indeks van Habitatintegriteit (IHI) bereik klaarblyklik die vereiste doel, maar is te subjektief. Kategorisering van die IHI-waardes word voorgestel. (3) 'n Goeie voorspeller van rivier-HI is die hoeveelheid natuurlike teenoor versteurde grondgebruik stroomop van 'n terrein op 'n streeks- en lokale skaal. Die sterk negatiewe effek van uitheemse plantegroei in die omgewing en lokale verstedeliking op stroom- (r² = -0.80, r² = 0.80, p<0.05 ) en oewer-HI (r² = -0.81, r² = -0.83, p<0.05) is beduidend. Verskille in tipe grondgebruik beïnvloed rivier-HI op verskillende vlakke; bestuurders moet dus plaaslik en aan die opvanggebied dink. (4) In die Houtbaairivier lyk dit asof 'n filtreringstelsel (bv. vleigrond) die waterkwaliteit tussen die middel- en lae gedeeltes verbeter. In die loop van die Lourensrivier is hoë totale opgeloste soute, geleidingsvermoë en anorganiese stikstofkonsentrasies in die middelgedeelte 'n rede tot kommer. In die Palmietrivier by Grabouw was die suurstof te min om die meeste akwatiese lewensvorme te onderhou. Opgedamde water in die middel gedeeltes dien as 'n sink vir voedingstowwe en soute, maar dit lyk asof die Huis- en Kromrivier die waterkwaliteit van die Palmietrivier stroomaf in die Kogelbergnatuurreservaat degradeer. Saam met die resultate van gelyktydige biotiese assesserings, kan hierdie resultate gebruik word vir die ontwikkeling van bestuursaksies om die ekologiese toestand van hierdie riviere te verbeter. Die resultate is gebruik in 'n toestand-van-riviere-verslag vir die Suidwes-Kaap.