State of the Bay Report 2011-Final.pdf - Anchor Environmental

State of Saldanha Bay & Langebaan Lagoon 2011
List of Figures
Figure 5.5.
Figure 5.6.
Figure 5.7.
Figure 5.8.
Figure 5.9.
Figure 5.10.
Figure 6.1.
Figure 6.2.
Figure 6.3.
Figure 6.4
Figure 6.5.
Figure 6.6
Figure 6.7
and blue lines) is indicative of improving water quality, while an upward slope in
these lines in indicative of decreasing water quality. .............................................. 68
Faecal coliform and E. coli logarithmic counts at 4 sampling stations within Big Bay
(Feb 1999-Feb 2012). A Downward slope of the regression (solid red and blue
lines) is indicative of improving water quality, while an upward slope in these lines
in indicative of decreasing water quality. ................................................................. 69
Faecal coliform and E. coli logarithmic counts at 3 sampling stations within
Langebaan Lagoon (Feb 1999-Feb 2012). A Downward slope of the regression
(solid red and blue lines) is indicative of improving water quality, while an upward
slope in these lines in indicative of decreasing water quality. ................................. 70
Faecal coliform and E. coli logarithmic counts at 3 sampling stations within
Langebaan Lagoon (Feb 1999-Feb 2012). A Downward slope of the regression
(solid red and blue lines) is indicative of improving water quality, while an upward
slope in these lines in indicative of decreasing water quality. ................................. 71
An illustration of the proposed routine monitoring programme to be trialled in
South Africa. Source: South African Water Quality Guidelines for Coastal Marine
Waters (RSADEA 2011). ............................................................................................ 73
Trace metal concentrations in mussels collected from five sites in Saldanha Bay as
part of the Mussel Watch Programme. (Source of data: G. Kiviets, Marine and
Coastal Management, Department of Environmental Affairs and Tourism).
Recommended maximum limits for trace metals in seafood as stipulated in South
African legislation are shown as a dotted red line. .................................................. 78
Concentrations of Cadmium, Lead and Mercury in mussels and oysters from four
bivalve culture operations in Saldanha Bay covering the period 1993 to 2010.
Recommended maximum limits for trace metals in seafood as stipulated in South
African legislation are shown as a dotted red line. .................................................. 79
A) Under natural circumstances, dune vegetation can “move” with the beach as it
erodes and accrete under the influence of natural processes. B) Protection of
infrastructure erected too close to the high water mark, on the other hand,
necessitates construction of artificial barriers and leads to the loss of the beach
ecosystem and associated amenities. ...................................................................... 83
Graph showing the relative change in area over time for Spreeuwalle and
Langebaan Beach (1960 – 2012). .............................................................................. 84
Spreeuwalle beach showing the position of the transect line in the middle of the
beach (Source: Gericke 2012). .................................................................................. 84
Variation in beach width across a transect of the central section of Spreeuwalle
beach (Source: Gericke 2012). .................................................................................. 85
Rock revetments constructed along the beach at Langebaan in an effort to protect
coastal infrastructure. .............................................................................................. 86
Groyne construction site Langebaan north beach. 1st groyne is completed and
position of 2nd groyne is show in white. Area A and B are sand “slurry” sites (see
text for explanation). Area C sand dredging site for beach reclamation. Source:
Prestedge Retief Dresner Wijnberg. ......................................................................... 87
State of the beach north of Groyne 2 in May 2010. (view looking south from the
middle of Leentjiesklip 1 beach towards the groyne) .............................................. 88
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