Includes bibliographical references (leaves 69-74). / Includes abstract. / Long-term ecosystem changes, such as regime shifts, have occurred in several marine ecosystems worldwide. Multivariate statistical methods have been used to detect such changes, but they have to date not been applied to the southern Benguela ecosystem. A weakness of many of the methods is that they require long time series data and do not provide robust results at the end of time series. A new method known as the sequential t-test algorithm for analysing regime shifts (STARS) is applied to a set of biological state variables and environmental and anthropogenic forcing variables in the southern Benguela.

Includes bibliographical references (leaves 64-70) / This study focuses on general features and variations of sea level at Zanzibar, and the relation of these to climate variability over the tropical western Indian Ocean during the 1997-1998 EI Niño and the 2000-2001 la Niña periods. The sea level data used in this study has been collected over a period of nine years from 1996 to 2004. Analyses have shown that the predominant type of tides at Zanzibar are semidiurnal with two high and two low water levels in each tidal day. Over the monthly cycle, two spring and two neap tides with different tidal ranges are observed. The tidal range may vary depending on the season of the year.

Includes bibliographical references (leaves 35-40) / An experimental trap fishery for the deep-water lobster spiny lobster Palinurus delagoae commenced in 2004, and was run until 2006. Data collected by on-board scientific observers were used to explore fishing effort, catches and catch per unit effort. The recent data were compared with those for a previous experiment conducted in 1994-1997, which apparently contributed to the collapse of the stock, to determine whether the stock had recovered and could sustain a trap fishery. There was a demonstrable recovery of the P. delagoae stock after the previous stock collapse, according to the catch rates and the size composition of catches between 2004-2006. However, catches of P. delagoae declined between 2004-2006. This was related to decreases in effort and in catch per unit effort over the three years. This, and a simultaneous decline in the by-catch of P. delagoae in the prawn trawl fishery off KwaZulu-Natal, suggests that the P. delagoae stock is extremely vulnerable to concomitant trawl and trap fishing. It is recommended that trap fishing should either be permitted at low levels of effort and catch only, or once more be suspended to allow the resource to recover.

Includes bibliographical references (leaves 69-72). / Characteristics of extreme wave events along the coast of South Africa were researched through a dataset obtained by CSIR wave recording network at four locations. The locations from west to east are Slangkop, FA-Platform (Agulhas bank), East London and Richards Bay. The longest dataset available was the 25-year dataset at Slangkop measured by accelerometer wave buoys. In the subsequent years the wave recording network along the South African coast was expanded to six locations at present.

Variations in the global climate over time have long been associated with changes in the meridional overturning circulation of the oceans. It is now commonly believed that, during the Last Glacial Maximum (LGM), the transport of North Atlantic Deep Water (NADW) to the southeast Atlantic Ocean was reduced. A popular method to trace these ambient changes is the stable isotope systematics of neodymium (given as εNd). In this study εNd data were measured on mixed planktic and bulk foraminifera from two gravity cores, GeoB8336-6 and GeoB8342-6, retrieved from the Cape Basin at water depths of 3524 and 3521 meters from the western continental slope of South Africa. The samples were prepared following the protocol presented by the Cambridge group (Tachikawa, Piotrowski, & Bayon, 2014). Planktic and bulk foraminifera samples taken from the same core depth interval had the same εNd ratios within error, which suggests that bulk foraminifera may provide a quick way to reconstruct ambient bottom water values. However, more research is needed to further support these findings. While the Holocene samples' εNd ratios (εNd(N36/6a) -10.7±0.3 and εNd(N42/6a mean) -10.2±0.4) lie within the range of modern Eastern NADW (εNd(modern ENADW) -10.9±1.2), glacial samples yield significantly more radiogenic εNd ratios (εNd(N42/6b) -7.7/ εNd(N36/6b) -8.1). This indicates the greater influence of southern-sourced water masses and thus provides further evidence for a reduction of NADW during the last glacial. MIS3 samples show ratios that lie in between those observed in the LGM and Holocene, and it is hypothesized that ocean circulation during MIS3 was comparable to that during the transition from the LGM to the Holocene (Termination I).

Includes bibliographical references. / Coral δ¹⁸O and Sr/Ca records from massive corals in the western Indian Ocean (WIO) are used to establish the heterogeneous distribution of warming rates across the tropical and subtropical regions and to investigate if it corresponds with that from instrumental sea surface temperatures (SSTs). The coral records correlate with instrumental data better on monthly time scales compared to annual time scales. Coral thermal stress was assessed by the Degree Heating Months (DHM) technique and even though the coral DHM aligns quite well with instrumental DHM, the values from coral data are generally 2-3 times greater in magnitude than the DHM values from instrumental data. It was found that the accumulated thermal stress, calculated from coral and instrumental data, for the majority of the tropical and subtropical WIO sites has been increasing since the 1970’s. From 1870 to 1995, both the tropics and the subtropics have been warming in general, although with different and varying rates as recorded by the coral and the instrumental SSTs. It was further revealed that both the tropical and the subtropical WIO warmed during the summer and winter periods during 1870-1995. On longer time scales, the relationship between the coral records in the WIO and climate indices showed a significant interannual variability approximately centered at periods 3-6 years, indicating a probable link with ENSO and IOD. The extent to which coral reefs from different sites in the WIO are prepared to survive climate change based on historical SST variability and intensity of warming rates are described. It could therefore be suggested that some corals may be more favoured to survive warming climate compared to others because corals in the WIO are located in different oceanographic conditions and experience different climatic variations.

Recent research has shown that higher cognitive functions and learning occur in teleosts and elasmobranchs. Very little is known about the cognitive abilities of benthic sharks and no research has been published on the learning ability of the endemic Leopard catshark (Poroderma pantherinum) species of South Africa. This species is listed as data deficient on the IUCN red list and known threats due to anthropogenic impacts include fatalities because of bycatch and depredation in the small-scale commercial fishing industry. It has been suggested that sharks can be attracted to fishing boats through the sound of outboard motors and an association can be formed between the sound and easy prey on the hooks of fisherman. This pilot study examined the learning capacity of Leopard catsharks in Hermanus, South Africa, by using a series of food-reward tests based on instrumental conditioning. A target with black and white stripes was used as the discriminative stimulus, while an auditory cue acted as a bridging stimulus for the food-reward task. Sharks were collected by hand whilst diving and shore-angling in Hermanus from August 2015 to November 2015 and acclimatised before the onset of experiments. Four juvenile sharks were trained through operant conditioning using visual and auditory stimuli for ten days each, consisting of six trials per day. A fifth juvenile shark, acting as the control, was trained through the same method without the auditory stimulus to test the influence thereof on the learning rates of Leopard catsharks. This study showed that Leopard catsharks have the ability to associate a visual stimulus with a food reward through the aid of an auditory cue. The auditory cue was also shown to increase learning rates significantly as an association was formed between the presence of food in front of the target and the auditory signal. The individual sharks in this study displayed differing levels of stress and learning rates. It is suggested that even though Leopard catsharks show high diversity in learning rates and adaptation to stress, they possess the ability to learn and adapt rapidly to changing environments. The results possibly have important implications for the understanding of learning and conditioning in Leopard catsharks and the likely anthropogenic threats caused through learned behaviour in benthic sharks.

Temporal variability in infection of South African male sardines (Sardinops sagax) by a testicular coccidian parasite Eimeria sardinae was examined between putative western and southern stocks of this fish species. Samples were collected by commercial vessels from five localities; Gansbaai, St Helena Bay, Mosselbay, Port Alfred and Port Elizabeth (west and south coast) between 2012 and 2013. A total of 461 sardines were examined for the presence of Eimeria sardinae, including 185 males and 41 females from west coast and 180 males and 55 females from the south coast. Sardine females did not show any infection by the parasite. For males, prevalence of infection was 74.9% for the western stock and 76.5% for the southern stock. Mean infection intensity and standard error of the western stock was 6.7±0.7 and for the southern stock was 8.3±1.0. Parasite abundance and standard error of the western stock was 5.3±0.2 and 6.1±0.3 for the southern stock. A significant difference was observed within testes position (anterior, middle and posterior), with anterior being highly infected followed by middle and posterior (KW chi-square = 86.029, df = 2, p<0.05). Infection from the left and right testes did not show a significant difference (W= 623, p = 0.13). There was no significant difference in prevalence of infection, infection intensity index and abundance index per region across seasons. Seasonal pattern was the same in both stocks. There was a significant difference in monthly average GSI data of male sardines from west and south coast between 1996-2014 (KW = 5416.9, df = 11, p < 0.01). There was no significant difference between seasonal GSI and seasonal infection intensity index.

Bibliography: leaves 24-25. / The aims of this study are to analyse the extent and distribution of boat and shore based fishing along the Cape Peninsula for the purpose of designing a comprehensive fisheries monitoring program. The focus of this study is the non-quota regulated fisheries, which have thus far eluded monitoring attempts. A fishery monitoring program should be able to detect biologically significant shifts in resource abundance in the Marine Protected Areas and to provide data that are relevant to stock assessment models. Personnel and cost implications of the monitoring program will be estimated.

Includes abstract. / Includes bibliographical references (leaves 151-155). / The development and underlying physical connections of relationships between SWC rainfall and the Southern Annular Mode (SAM), South Atlantic sea surface temperature (SST), Antarctic sea ice concentration (SIC), and the EI Nino-Southern Oscillation (ENSO) were explored using spatial and temporal correlations. Insight gained from the correlation analysis was used to develop statistical forecast models for SWC seasonal rainfall, which served as an initial assessment of the potential for statistical seasonal forecasting of SWC rainfall.