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

State of Saldanha Bay & Langebaan Lagoon 2011
Recommendations
contaminants are typically associated with the finer sediment fraction and are highest in the most
quiescent areas of the Bay (i.e. In the Yacht basin and adjacent of the Multipurpose terminal).
Sediment monitoring (particle size, particulate organic carbon and trace metals) should
continue to be conducted annually at the same suite of stations that have been monitored since
1999 along with additional stations added since this time (e.g. those in Langebaan Lagoon).
Dredging in the Bay should be avoided if at all possible, and appropriate precautions need to be
taken when dredging become necessary to ensure that suspended trace metals do not reach
cultured organisms in the Bay.
12.3.2 Hydrocarbons
Poly-cyclic, poly-nuclear compounds and pesticides were considered to pose no threat during
analysis conducted in 1999. This has been confirmed through more recent studies (2010). It is
recommended, however, that these pollutants should be monitored approximately every five years.
12.4 Benthic macrofauna
A range of benthic community health indicators examined in this study over the period 1999 to 2011
has revealed that benthic health most likely deteriorated in Small Bay from 1999 to 2008, but has
recently (2009-2011 surveys) started to show signs of recovery. Benthic health within Big Bay
improved marginally between 1999 and 2008 after which it decreased again to a state similar to that
observed in 1999. There has been little change in benthic health within Langebaan Lagoon over the
last decade. Small Bay and Big Bay have both suffered a significant reduction in species diversity
over the last decade, although Small Bay, and in some cases Big Bay, is showing signs of recovery.
Most notable is the return of the suspension feeding sea-pen Virgularia schultzei to Big Bay since
2004 as well as an increase in the percentage biomass of large, long lived species such as the tongue
worm Ochaetostoma capense, and several gastropods. Although benthic health within Small Bay is
showing signs of improvement, the health status of this site is still lower than that of Big Bay and
Langebaan Lagoon. In order to ensure the continued improvement in the health of the Small Bay
marine environment it is recommended that stringent controls are placed on the discharge of
effluents into Small Bay to facilitate recovery of benthic communities in this extremely important
area.
The most impoverished site was situated in the Yacht Club harbour, where benthic species
were virtually absent and the concentration of certain contaminants was highest. The Yacht Club
harbour should thus be targeted as a key area of concern more stringent management procedures
should be implemented to reduce the discharge and contamination of contaminants at this site.
This regularity (annually) and intensity of benthic macrofauna monitoring should continue at all of
the current stations.
12.5 Rocky intertidal
Key changes in the rocky intertidal ecosystem reflect the regional invasion by the Mediterranean
mussel Mytilus galloprovincialis and the North American barnacle Balanus glandula which compete
for space on most of the rocky intertidal substrata in the bay at the expense of the native species.
Their spread throughout the Bay has significantly altered natural community structure in the mid
and lower intertidal, particularly in wave exposed areas.
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