Browsing by Subject "False Bay"

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    A preliminary account of investigations into the False Bay sublittoral by the use of a diving helmet
    (1950) Jackson,Peter Brian Neville
    A great deal of work has been done on the ecology of the intertidal some of South African by the Zoology Department of the University of Cape Town under the direction of Professor T.A. Stephenon. As a result of this a number of valuable papers have been published dealing with the plants and animals of the zone, their ecology, lateral and vertical distribution and so on. Stephenon has, in three papers (1939, 1944,1947), dealt with general results and conclusions drawn from this survey. This work dealt entirely with the biotic between tidelevels, i.e., from the sublittoral fringe upward. it did not take into account the sublittoral, that part of the shallow coast which is perpetually submerged at all tides.
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    Open Access
    A preliminary account of investigations into the False Bay sublittoral by the use of a diving helmet
    (1950) Jackson, P B N (Peter Brian Neville), 1923-
    A great deal of work has been done on the ecology of the intertidal some of South African by the Zoology Department of the University of Cape Town under the direction of Professor T.A. Stephenon. As a result of this a number of valuable papers have been published dealing with the plants and animals of the zone, their ecology, lateral and vertical distribution and so on. Stephenon has, in three papers (1939, 1944,1947), dealt with general results and conclusions drawn from this survey. This work dealt entirely with the biotic between tidelevels, i.e., from the sublittoral fringe upward. it did not take into account the sublittoral, that part of the shallow coast which is perpetually submerged at all tides.
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    A prominent colour front in False Bay, South Africa: Cross-frontal structure, composition and origin
    (Elsevier, 2008) Waldron, H N; Wainman, C K; Waldron, M E; Whittle, C; Brundrit, G B
    Colour fronts are a frequent occurrence in False Bay, South Africa, and their occurrence has been the subject of previous study and anecdotal conjecture. The opportunity arose to make a cross-frontal study of this feature in November 2005. Photographs were taken and, subsequently, satellite imagery was obtained. Measurements were made of temperature, salinity, turbidity, dissolved oxygen, suspended solids, plant nutrients and chlorophyll a. Cross-frontal comparisons were also made on particulate material using a scanning electron microscope (SEM) and elemental dispersive x-ray (EDX) analysis. Frontal waters were milky white-green in colour, in stark contrast to the adjacent clearer, green-blue waters. The milky white-green water (MW-GW) was found to be warmer, (apparently) less saline, more turbid, richer in nitrate and silicate and had a higher chlorophyll a concentration. The dissolved oxygen signal was less pronounced, both water types being supersaturated. Paradoxically, in spite of the higher turbidity in the MW-GW, both water types had similar weights of suspended solids, although the MW-GW material was found to be more abundant and fragmentary when compared with its green-blue water (G-BW) counterpart. The MW-GW was rich in calcium whereas the G-BW was silicon enriched. The central findings of this study are that the strong southerly, onshore wind conditions prior to MW-GW formation introduced calcium-rich, fine particulates into the waters of the surf-zone. The sources of these particulates are thought to be the sea bed sediments and the sea/land interface. The particulates are close to neutral buoyancy enabling the MW-GW to persist over the time-scale of days. A mechanism reinforced by the warming of this water in the nearshore zone. The water was then advected by windforcing and subsequently, its own inertia around the north-west corner of False Bay, at which stage it was easily observed and sampled. It is suggested that the eventual collapse of the front was due to the slowing down of inertial movement in combination with the passive sinking of fine particulates and evaporative cooling resulting in downward convection.
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    Summer at the beach: spatio-temporal patterns of white shark occurrence along the inshore areas of False Bay, South Africa
    (BioMed Central, 2018-05-22) Kock, Alison A; Photopoulou, Theoni; Durbach, Ian; Mauff, Katya; Meÿer, Michael; Kotze, Deon; Griffiths, Charles L; O’Riain, M Justin
    Background Understanding white shark (Carcharodon carcharias) habitat use in coastal areas adjacent to large cities, is an important step when formulating potential solutions to the conservation conflict that exists between humans and large predatory sharks. In this study, we present the findings of a 2.5-year study of white shark occurrence and movement patterns adjacent to the City of Cape Town in False Bay, South Africa, with a focus on spring and summer months. Fifty-one white sharks were monitored annually at three offshore and twelve inshore sites by VR2 acoustic receivers, over 975 days from 1 May 2005 to 31 December 2007. Results Occurrence patterns at inshore sites during spring and summer were analysed using a generalized additive mixed model (GAMM) with a spatial term (longitude, latitude), time of day and year included as explanatory variables for site use. We found that sharks occurred more frequently at inshore sites along the northern and northwestern shores, compared to the rest of the bay, and they transitioned most frequently between four adjacent beach sites that encompass the most popular recreational water use areas in Cape Town. There was significant diel variation, with higher shark occurrence around midday, and a peak in shark occurrence in 2005, when human-shark interactions also peaked. However, we found no effect of shark size on occurrence patterns at inshore sites. Conclusions White sharks showed the highest levels of occurrence at specific inshore sites between Muizenberg and Strandfontein beach, and thus inclusion of these sites within False Bay’s marine protected area (MPA) network or recognition as Ecological or Biological Significant Areas (EBSAs) should be a future consideration. These insights into white shark habitat use at inshore sites in False Bay are important for successfully applying the principles of marine spatial planning (MSP) and for making science-based policy decisions. Furthermore, this information can be used to reduce potential shark-human conflict by incorporating it into future shark safety education campaigns.
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