Mossel Bay Research Articles

Migration of Pleistocene shorelines across the Palaeo-Agulhas Plain: Evidence from dated sub-bottom profiles and archaeological shellfish assemblages

Intertidal zones on shorelines are geologically complex features of the coastal plain, shaped by heterogeneous substrate lithologies. Palaeocoastlines have been heavily modified by sea-level change, ocean currents, wind, waves and swell. Rocks and sediments along intertidal zones create rich habitats for biogenic forms including shellfish, which are highly sensitive to subtle variations in underlying lithology. Here, we assess Pleistocene shoreline migrations on the south coast of South Africa in relation to fluctuating sea-levels and changes in sediment supply. The study area extends from Still Bay to Mossel Bay, South Africa, with a particular focus on Pinnacle Point. Our goal is to better understand the changes to the intertidal zone along these palaeocoastlines and how this may have affected marine resources available to early humans. We interpret marine geological records at select time slices along sub-bottom profiled transects that run perpendicular to the coast. We describe the character of specific shorelines to establish expectations of coastline character which we then compare to archaeological records at Pinnacle Point. We base our interpretations on (1) significant events in Pleistocene glacio-eustatic and depositional records, such as widespread deposition of coastal sand dunes at ∼90, ∼74 and ∼50 ka [MIS 5e–MIS 4], and (2) empirical evidence from high-resolution records of shellfish assemblages at the archaeological sites of PP13B and PP5-6. We demonstrate a prevalence of dissipative beaches and mixed coasts on Pleistocene sea-level lowstands on the coast of the Palaeo-Agulhas Plain. This differs significantly from the modern coastline with its significance of rocky shorelines.

Spatio-temporal genetic variation of juvenile smooth hammerhead sharks in South Africa

ABSTRACTThe smooth hammerhead shark Sphyrna zygaena is known to display a high degree of site fidelity to specific areas along the South African coastline. This species is vulnerable to overfishing and steep declines have been noted globally. In this study, a dual marker approach was used to investigate the spatial and temporal genetic variation of juvenile S. zygaena across the south and east coast of South Africa. Kinship of individuals was determined within and across cohorts from juvenile S. zygaena sampled in Mossel Bay, a putative pupping ground. Significant genetic differentiation (supported by F-statistics, multivariate analysis and Bayesian clustering) was evident between individuals sampled from the warm temperate south coast and the subtropical east coast, with asymmetric gene flow between regions. Distinct genetic composition was also revealed between sampling years, with different levels of relatedness within and among cohorts, indicating different temporal populations utilizing Mossel Bay annually. Based on these results, further investigation of S. zygaena populations across a wider region is warranted in order to make recommendations regarding conservation management of this vulnerable coastal shark.

Using mark-recapture methods to estimate population size and survival of pyjama sharks Poroderma africanum in Mossel Bay, South Africa

The pyjama shark Poroderma africanum (family Scyliorhinidae) is endemic to coastal waters of South Africa but its population characteristics are poorly known. This study aims to estimate baseline demographic parameters for P. africanum in Mossel Bay. We applied mark-recapture methods following Pollock’s robust design (PRD) and Cormack–Jolly–Seber (CJS) models, using five-year tag-recapture data and one-year acoustic-telemetry data, respectively. Estimates of abundance, survival, capture probabilities and temporary emigration were obtained using these models. The PRD model indicated random temporary emigration (0.955 period–1 [95% CI 0.755–0.993]), constant survival, and season-varying capture and recapture probabilities with a negative behavioural response to first capture (β = −5.34 [−6.89 to −3.80]). Abundance estimates ranged from 11 (10.01–13.21) to 53 (52.05–56.82) sharks in Mossel Bay. The CJS model indicated constant survival (0.271 y–1 [95% CI 0.0–0.75]) and sex-independent probabilities of being captured at least once annually (1.0 y–1 for both sexes). This study provides the first demographic information for the management of this population. Further studies should utilise larger sample sizes and more complex models, and investigate specific management options.

Cape fur seals (Arctocephalus pusillus pusillus) adjust traversing behaviour with lunar conditions in the high white shark (Carcharodon carcharias) density waters of Mossel Bay, South Africa

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 622:219-230 (2019) - DOI: https://doi.org/10.3354/meps13051 Cape fur seals (Arctocephalus pusillus pusillus) adjust traversing behaviour with lunar conditions in the high white shark (Carcharodon carcharias) density waters of Mossel Bay, South Africa P. Morse1,*, M. A. Mole2, M. N. Bester2, R. Johnson1, U. Scacco3, E. Gennari1,4,5 1Oceans Research Institute, PO Box 1767, Mossel Bay 6500, South Africa 2Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield 0028, Gauteng, South Africa 3ISPRA-Italian National Institute for Environmental Protection and Research, Via Vitaliano Brancati, 60, 00144 Roma, Italy 4South African Institute for Aquatic Biodiversity (SAIAB), Private Bag 1015, Grahamstown 6140, South Africa 5Department of Ichthyology and Fisheries Science, Rhodes University, PO Box 94, Grahamstown 6140, South Africa *Corresponding author: peter.morse@my.jcu.edu.au ABSTRACT: White sharks Carcharodon carcharias are highly visual predators, leading to the hypothesis that the predation risk for foraging Cape fur seals Arctocephalus pusillus pusillus might differ with ambient light conditions. This study investigated the relationship between environmental fluctuations of ambient light and the traversing behaviour of Cape fur seals in and out of their colony at Mossel Bay, South Africa, to better describe potential predator avoidance strategies. A total of 12 144 traversing events were observed over a 4-yr period and there was an overall trend for Cape fur seals to traverse less often but in relatively larger group sizes during periods when white sharks are suggested to be more active. Specifically, Cape fur seal activity was reduced during winter when white sharks are most actively hunting, and most traversing behaviour occurred at night when Cape fur seals were less likely to be detected by white sharks. However, among nocturnal observations, Cape fur seal group sizes increased significantly with moonlight. Although nocturnal predations of Cape fur seals by white sharks have been observed before in Mossel Bay, this is the first study to indicate Cape fur seals might respond to the increased risk of improved white shark visual acuity during moonlit nights by seeking safety in numbers while foraging. Further investigations are needed to assess the effect of the lunar cycle on white shark nocturnal hunting behaviour, but observations presented here suggest that white sharks may pose a bigger threat to Cape fur seals under the light of a full moon. KEY WORDS: Predator avoidance · Pinniped · Lunar cycle · Safety in numbers · Mobbing · Predator-prey Full text in pdf format PreviousCite this article as: Morse P, Mole MA, Bester MN, Johnson R, Scacco U, Gennari E (2019) Cape fur seals (Arctocephalus pusillus pusillus) adjust traversing behaviour with lunar conditions in the high white shark (Carcharodon carcharias) density waters of Mossel Bay, South Africa. Mar Ecol Prog Ser 622:219-230. https://doi.org/10.3354/meps13051 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 622. Online publication date: July 18, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

A high-resolution perspective on MIS 5c-d lithic assemblages from Klasies River main site Cave 1

Klasies River contains an extensive MIS 5 MSA sequence, mostly from what has been described as the MSA ll, MSA 2a or the Mossel Bay techno-complex. The current Witness Baulk excavations undertaken between 2015 and 2016 allows for a renewed and detailed investigation of the variability of the lithic technology from the lowermost part of the MSA ll. This assemblage is equivalent to Deacon's SASL sub-member and Layers 17a and b of Singer and Wymer. Two phases are recognized: An MIS 5c phase in layer SMONE (Singer & Wymer layer 17a) and an MIS 5d phase in layers BOS One and BOS Two (Singer & Wymer layer 17 b). The two phases are characterized by commonalities such as a focus on quartzite utilisation, the presence of a main unidirectional reduction system, similar end products which comprise of points, blades and flakes and a low amount of formal tools. However, this high-resolution investigation of the layers reveals temporal variability. In the Shell Midden ONE (SMONE) layer cores and products are relatively lighter and small debitage is more frequent. There are more flake end products and compared to the lower layer, there are fewer tool types. In the Black Occupational Soil (BOS) layer points and blades are more numerous, products are heavier, core types are more variable, and a higher frequency and variety of tool types occur. Such detailed differences within the MIS 5 assemblages from Klasies River, not described before, shows that the MSA ll is not a homogeneous entity, and that subtle patterning occurs that may link to different technological strategies. Compared to other MIS 5 sites on the southern Cape, namely Blombos Cave, Pinnacle Point and Cape St. Blaize, a common pattern in place provisioning is seen, although the technology shows differences between the sites. This study indicates the value of more detailed studies of MIS 5 assemblages as a tool to understand variability from a more refined perspective.

Institutional tuberculosis infection control in a rural sub-district in South Africa: A quality improvement study

BackgroundTuberculosis (TB) is a major global health challenge, and South Africa is one of the high-burden countries. A national TB infection control (TBIC) guideline has stipulated three areas of infection control at health facilities: work practice and administrative control, environmental control, and personal protection for health workers.AimThe aim of this study was to identify the gaps and address the challenges in institutional TBIC.SettingThe district hospital and a primary health care clinic within the Mossel Bay sub-district in the Western Cape.MethodsAccording to the national TBIC draft guideline, a quality improvement cycle was used to evaluate and improve TBIC. Each facility had an existing infection and prevention control and occupational health and safety team, which were used as the audit teams.ResultsA baseline assessment was followed by a set of interventions, which did not show a significant improvement in TBIC. The difference between the pre- and post-intervention TB screening rate was not statistically significant. An assessment of time interval between 101 patients presenting with TB symptoms and diagnosed with TB was 4 days at baseline and post-intervention. Most of the anticipated improvements were dependent on the health workers’ adherence to the local TBIC policies, which emerged as an unexpected finding.ConclusionWe found good managerial commitment reflected by the presence of various policies, guidelines, specific personnel and committees to deal with infection control in general. This study has created awareness about TBIC among staff and pointed out the complexity of health workers’ behaviour towards adhering to policies.

A note on the depots of the 1897 Andrée balloon expedition

AbstractRecent research suggests that the members of the 1897 Andrée balloon expedition could have survived if they had marched towards the depot at Seven Islands instead of the Cape Flora depot after the forced landing at 82°56’N 29°52’E, and furthermore, that they reasonably should have done so given what they knew about the ice drift in the area. This paper comprises an analysis of the expedition’s depots based on a review of original sources, and the results elucidate Andrée’s initial decision to march towards Cape Flora. The Seven Island depot was not yet laid when Andrée departed in his balloon, and the information he had at the time indicated that it was highly uncertain that depot could be laid at all. Moreover, he knew it might be difficult to find the depot even if it had been laid since no exact position for it could be determined in advance. If he arrived at the Seven Islands without being able to obtain supplies there, Andrée knew he would have to continue all the way to Nordenskiöld’s old hut in Mossel Bay. Cape Flora, on the other hand, was certain to offer both supplies and shelter.

Molecular characterization of an outbreak of enterovirus-associated meningitis in Mossel Bay, South Africa, December 2015\u2013January 2016

BackgroundHuman enteroviruses (HEVs) are common causal agents of aseptic meningitis in young children. Laboratory and syndromic surveillance during December 2015 and January 2016 noted an unusually high number of paediatric aseptic meningitis cases at a hospital in Mossel Bay, Western Cape Province, South Africa. HEV was detected in clinical samples, prompting an outbreak investigation.MethodsEpidemiological investigations were conducted to ascertain possible linkage between cases. Amplification, sequencing and phylogenetic analysis of the 5’UTR and VP1 regions was undertaken to determine the HEV serotype associated with the outbreak as well as other cases of aseptic meningitis in the area in the preceding 6 weeks.ResultsOver the 2-month period, 63 CSF samples were available for testing. A total of 43 outbreak cases (68.3%) were observed, and the 26 (60.5%) that could be typed were coxsackie virus A9 (CVA9). Children attending three crèche facilities were epidemiologically linked, accounting for 60.5% (26/43) of the CVA9 cases. The majority of patients were under 10 years of age (55/63, 87.3%) and there was a male predominance (66%). Nucleotide sequence analysis of the 5’UTR and VP1 regions identified 2 lineages of CVA9 co-circulating during the outbreak, although the VP1 capsid protein sequence was identical as all nucleotide differences were synonymous. There was a unique isoleucine at position 64 and all outbreak viruses had a valine to threonine change in the hypervariable BC loop of VP1. Other HEV types circulating in the preceding period were echovirus 30 (n = 4), echovirus 5 (n = 3) and 1 each of echovirus 6, echovirus 9 and echovirus 15.ConclusionCVA9 was identified as the pathogen responsible for the large outbreak of aseptic meningitis, with 2 distinct co-circulating lineages.

Phytoliths as an indicator of early modern humans plant gathering strategies, fire fuel and site occupation intensity during the Middle Stone Age at Pinnacle Point 5-6 (south coast, South Africa).

The study of plant remains in archaeological sites, along with a better understanding of the use of plants by prehistoric populations, can help us shed light on changes in survival strategies of hunter-gatherers and consequent impacts on modern human cognition, social organization, and technology. The archaeological locality of Pinnacle Point (Mossel Bay, South Africa) includes a series of coastal caves, rock-shelters, and open-air sites with human occupations spanning the Acheulian through Middle Stone Age (MSA) and Later Stone Age (LSA). These sites have provided some of the earliest evidence for complex human behaviour and technology during the MSA. We used phytoliths—amorphous silica particles that are deposited in cells of plants—as a proxy for the reconstruction of past human plant foraging strategies on the south coast of South Africa during the Middle and Late Pleistocene, emphasizing the use and control of fire as well as other possible plant uses. We analysed sediment samples from the different occupation periods at the rock shelter Pinnacle Point 5–6 North (PP5-6N). We also present an overview of the taphonomic processes affecting phytolith preservation in this site that will be critical to conduct a more reliable interpretation of the original plant use in the rock shelter. Our study reports the first evidence of the intentional gathering and introduction into living areas of plants from the Restionaceae family by MSA hunter-gatherers inhabiting the south coast of South Africa. We suggest that humans inhabiting Pinnacle Point during short-term occupation events during Marine Isotope Stage (MIS) 5 built fast fires using mainly grasses with some wood from trees and/or shrubs for specific purposes, perhaps for shellfish cooking. With the onset of MIS 4 we observed a change in the plant gathering strategies towards the intentional and intensive exploitation of dry wood to improve, we hypothesise, combustion for heating silcrete. This human behaviour is associated with changes in stone tool technology, site occupation intensity and climate change.

Depositional and sea-level history from MIS 6 (Termination II) to MIS 3 on the southern continental shelf of South Africa

Pleistocene shoreline deposits comprised of calcified shallow marine (palaeobeach) and aeolian (palaeodune) facies found along mid-latitude coastlines can be useful indicators of past sea levels. Here, we describe a succession of such deposits that are presently exposed both above (subaerial) and below (submerged) mean sea level along the southern Cape coast of South Africa, 18 km east of the town of Mossel Bay. The submerged units provide a window on Late Pleistocene coastal processes, as palaeoshoreline deposits in this study extend to water depths of up to 55 m on the mid-shelf. Five sedimentary facies were identified in the strata and were compared to modern depositional environments of the local littoral zone, which include aeolian dune, upper shoreface, foreshore, intertidal swash and back-barrier settings. Twenty-two geological units were observed and mapped. Some of these units were directly dated with optically stimulated luminescence (OSL) dating. OSL ages were obtained for ten samples from the subaerial and twelve samples from the submerged deposits. Those geological units not directly dated were interpreted based on sedimentology and field/stratigraphic relationships to dated units. The stratigraphy and chronology of the succession indicates a record of initial deposition during Termination II (T-II) meltwater events, preceding and leading to marine isotope stage (MIS) 5e. Indicators for multiple sea-level fluctuations between MIS 5d and MIS 4, and sediment deposition at the end of MIS 4 and start of MIS 3 are also found. Both regressive and transgressive depositional cycles are well-preserved in the succession. We propose that palaeodune and palaeobeach deposits along the South Coast of South Africa have no clear preference for deposition during sea-level transgressions or regressions. Sediment deposition more closely mirrors the rate of sea level change, with deposition and preservation either during times of rapid sea-level movement, or oscillation around still-stand events. Periods of relatively slow average rise or fall of sea level are represented by erosional planation surfaces in this record.

How Important Are Blue Flag Awards in Beach Choice?

ABSTRACT Saayman, M. and Saayman, A., 2017. How important are Blue Flag awards in beach choice? South Africa's almost 3000-km coastline has long stretches of sandy beaches. An important yardstick for measuring their quality is the Blue Flag award, desired by beach and coastal management agencies. This paper investigates whether the Blue Flag status necessarily attracts a different beachgoer. It asks whether clear differences can be found between beachgoers at Blue Flag and non-Blue Flag beaches. Surveys of beachgoers were conducted during summer (March to April 2014) at six beaches near Cape Town and three near Mossel Bay. Four of these nine Western Cape beaches had Blue Flag status. The data from 374 completed questionnaires collected via random sampling were analysed using principal component analysis and logistic regression analysis. The results showed that seven beach-specific attributes attract beachgoers, with the most important ones being beach cleanliness and infrastructure. The results of the log...

Rainfall isotopic variability at the intersection between winter and summer rainfall regimes in coastal South Africa (Mossel Bay, Western Cape Province)

Rainfall isotopic variability at the intersection between winter and summer rainfall regimes in coastal South Africa (Mossel Bay, Western Cape Province)

Southern Hemisphere anticyclonic circulation drives oceanic and climatic conditions in late Holocene southernmost Africa

Abstract. Due to the high sensitivity of southern Africa to climate change, a reliable understanding of its hydrological system is crucial. Recent studies of the regional climatic system have revealed a highly complex interplay of forcing factors on precipitation regimes. This includes the influence of the tropical easterlies, the strength of the southern hemispheric westerlies as well as sea surface temperatures along the coast of the subcontinent. However, very few marine records have been available in order to study the coupling of marine and atmospheric circulation systems. Here we present results from a marine sediment core, recovered in shallow waters off the Gouritz River mouth on the south coast of South Africa. Core GeoB18308-1 allows a closer view of the last ∼ 4 kyr. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as indicators for sea surface temperatures and soil input, give information on oceanographic and hydrologic changes during the recorded time period. Moreover, the micropaleontology, mineralogical and elemental composition of the sediments reflect the variability of the terrigenous input to the core site. The combination of down-core sediment signatures and a catchment-wide provenance study indicate that the Little Ice Age ( ∼ 300–650 cal yr BP) was characterized by climatic conditions favorable to torrential flood events. The Medieval Climate Anomaly ( ∼ 950–650 cal yr BP) is expressed by lower sea surface temperatures in the Mossel Bay area and humid conditions in the Gouritz River catchment. These new results suggest that the coincidence of humid conditions and cooler sea surface temperatures along the south coast of South Africa resulted from a strengthened and more southerly anticyclonic circulation. Most probably, the transport of moisture from the Indian Ocean by strong subtropical easterlies was coupled with Agulhas Bank upwelling pulses, which were initiated by an increase in Agulhas Current strength.

Case study from the southern Cape linefishery 1: The difficulty of fishing in a changing world


 
 
 Variability on multiple temporal and spatial scales exposes fishers and fishing communities to multiple stressors. The impact and interplay of these stressors need to be considered to improve our understanding of social-ecological linkages if sustainable livelihoods are to be promoted. To this end, participant-led research was conducted in the small-scale traditional commercial linefishery of the southern Cape (South Africa) between Witsand and Mossel Bay. Knowledge and perceptions regarding stressors responsible for changes in the social-ecological system, which ultimately affect the fishers’ ability to fish successfully, were recorded using semi-formal interviews and focus groups with 50 participants. The results presented not only offer valuable insights into the day-to-day experiences of these fishers, but also expose knowledge gaps that exist in micro-scale interactions influencing the fishery system. An analysis of various stressors is presented, which includes the impacts of and responses to climate variability; challenges presented by fisheries policies and regulatory frameworks; social and economic considerations; inadequate infrastructure; and general political considerations. The development of a more comprehensive understanding of stressors that affect the social-ecological system at various scales provides valuable insights into a fishery system that is currently not well described, and provides the basis for analyses into vulnerability and resilience.
 
 
 
 
 Significance: 
 
 
 
 Understanding the impact and interplay of stressors at multiple scales is important if sustainable livelihoods are to be promoted.
 This research provides insight into the day-to-day experiences of fishers whilst exposing knowledge gaps that exist at a micro-scale.
 
 
 

Cetopirus complanatus (Cirripedia: Coronulidae) from the late Middle Pleistocene human settlement of Pinnacle Point 13B (Mossel Bay, South Africa).

The late Middle Pleistocene cave site of Pinnacle Point 13B (PP13B, South Africa) has provided the archaeologically oldest evidences yet known of human consumption of marine resources. Among the marine invertebrates recognised at PP13B, an isolated whale barnacle compartment was tentatively determined as Coronula diadema and regarded as indirect evidence of human consumption of a baleen whale (likely Megaptera novaeangliae). In this paper we redetermine this coronulid specimen as Cetopirus complanatus. This record significantly extends the fossil history of C. complanatus back by about 150 ky, thus partially bridging the occurrence of Cetopirus fragilis in the early Pleistocene to the latest Quaternary record of C. complanatus. Since C. complanatus is currently known as a highly specific phoront of right whales (Eubalaena spp.), we propose that the late Middle Pleistocene human groups that inhabited PP13B fed on a stranded southern right whale. Therefore, the whale barnacle from PP13B suggests the persistence of a southern right whale population off South Africa during the predominantly glacial MIS 6, thus evoking the continuity of cetacean migrations and antitropical distribution during that global cold phase. Interestingly, the most ancient evidence of humans feeding on a whale involves Eubalaena, historically the most exploited cetacean genus, and currently still seriously threatened with extinction due to human impact.

How solitary are white sharks: social interactions or just spatial proximity?

White sharks (Carcharodon carcharias) are circumglobally distributed large apex predators. While ecologically important, there is very limited study of their social behaviour. Although evident in other large, apex marine predators (e.g. toothed whales) and smaller elasmobranchs (e.g. blacktip reef sharks), the ability of any large pelagic elasmobranch to demonstrate social preferences, tolerance or grouping behaviour is largely unknown. Here, we test whether white sharks in a near-coastal environment form non-random associations with other conspecifics or simply share the same space at the same time. We photo-identified 323 individuals—74 % juvenile females (175–300 cm)—during chumming events at six different sites in Mossel Bay, South Africa, over a 6-year period (2008–2013), and tested for grouping behaviour. We found evidence for random associations among individuals, though spatio-temporal co-occurrence of white sharks in close proximity was weakly structured according to sex and, potentially, body size. Such biological traits may play a minor part in structuring co-occurrence of individuals at fine spatio-temporal scales, which could reflect ontogenetic preferences in diet and site fidelity, or differing tolerance levels for conspecifics of different sexes and sizes. Our study strengthens the evidence that large pelagic shark species are generally solitary and display limited social behaviour. Large pelagic shark species are important top predators, but we know little about their social behaviour. We tested the ability of white sharks (C. carcharias) to form groups and display social preferences for other individuals when they congregate at scavenging events in a coastal environment, where social interactions may be more likely. We found that white sharks co-occur at random, displaying no preferred or avoided associations for other individuals. Nevertheless, there was a minor influence of biological traits, with individuals aggregating according to gender and, possibly, body size. While we hypothesise these effects could represent preferences in diet and site fidelity, or more tolerance for similar-sized individuals of the same sex, our study strengthens the evidence that white sharks are mostly solitary foragers.

Stratigraphy of incised channels on the Mossel Bay continental shelf, South Africa

Stratigraphy of incised channels on the Mossel Bay continental shelf, South Africa

Former land surfaces and palaeoshorelines on the Mossel Bay continental shelf, South Africa

Former land surfaces and palaeoshorelines on the Mossel Bay continental shelf, South Africa

Pleistocene molluscs from Klasies River (South Africa): Reconstructing the local coastal environment

We explore if taxonomic analysis of archaeological mollusc assemblages can be used to reconstruct Late Pleistocene (MIS 5–3) coastal environments at Klasies River in South Africa. To obtain a balanced reconstruction, we analyse the large molluscs separately from the so-called incidentals, the small mollusc species. Based on modern mollusc habitat preferences and tolerances we identify four different eco-profiles to help characterise sea surface temperatures and the character of the shore: temperature profile; geographical distribution; substrate; wave interaction. We hypothesise that changes in the Klasies River mollusc community/eco-profiles can be linked to global glacial and interglacial events and we define several testable assumptions. We found that in response to global warming and cooling events, the Klasies River mollusc communities change slightly, yet significantly. Other sources of marine environmental data confirm that average sea surface temperatures gradually decreased, but probably remained within the modern southern east coast range of variation. It appears that coastal sea surface temperatures of the warm Agulhas current were not particularly depressed during the occupation sequence. The character of the coastal topography does change more apparently during the occupation sequence of the sites and with it the mollusc assemblages: from an interglacial rocky shore in the Klasies and two Mossel Bay phases to a more glacial sandy environment during the Howiesons Poort and the MSA III. In conclusion, the temperature tolerance levels of many Klasies River mollusc species are too broad to reflect small changes in sea surface temperatures. However, in conjunction with other eco-profiles and environmental proxies, such as substrate requirements and oxygen isotopes, the temperature approximations are useful, particularly when evaluating large scale sea surface temperature fluctuations. For the characterisation of the shore and substrate we found the eco-profile approach very useful.

Abundance and degree of residency of humpback dolphins Sousa plumbea in Mossel Bay, South Africa

Indian Ocean humpback dolphins Sousa plumbea inhabit nearshore waters from South Africa to eastern India. Humpback dolphins are vulnerable to conservation threats due to their naturally small population sizes and use of nearshore habitats, where human activities are highest. We investigated the abundance and residency of this species inhabiting Mossel Bay, South Africa, using photographic mark-recapture. Data were collected during 81 surveys in Mossel Bay between 2011 and 2013. Open population modelling using the POPAN parameterisation produced a ‘super-population’ estimate of 125 individuals (95% CI: 61–260) and within-year estimates of between 33 and 86 individuals (2011: 71 [95% CI: 30–168]; 2012: 33 [15–73], 32 [15–70]; 2013: 46 [20–108]). Although less appropriate, closed capture models were also run for comparison with previous studies in the region and generated similar, but slightly smaller, population estimates within each year. We compared our catalogue with opportunistic data collected from East London, Plettenberg Bay, De Hoop and Gansbaai. The only catalogue matches attained were between Plettenberg Bay (n = 44 identified) and Mossel Bay (n = 67 identified), separated by 140 km. Population exchange was moderate, with nine individuals resighted in multiple years between these two areas. This study supports previous findings of long-range movements for this species and provides a baseline from which to assess future impacts on the population.