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

State of Saldanha Bay & Langebaan Lagoon 2011
Activities & discharges
3 ACTIVITIES AND DISCHARGES AFFECTING THE HEALTH OF THE
BAY
3.1 Introduction
Industrial development of Saldanha Bay dates back to the early 1900’s with the establishment of a
commercial fishing and rock lobster industry in the Bay. By the mid-1900’s Southern Seas Fishing
Enterprises and Sea Harvest Corporation had been formed, with Sea Harvest becoming the largest
fishing operation in Saldanha Bay to date. Human settlement and urbanization grew from village
status in 1916, to an important city today with well over 28 000 people and an average population
growth rate of 5.73% per year. With increasing numbers of fishing vessels operating in Saldanha
Bay, and to facilitate the export of iron ore from the Northern Cape, the harbour was targeted for
development in the early 1970’s. The most significant developments introduced at this time were
the causeway linking Marcus Island to the mainland, to provide shelter for ore-carriers, and the
construction of the iron ore terminal. By the end of the 1970’s Saldanha Bay harbour was an
international port able to accommodate large ore-carriers and deep-sea trawlers. During the 1980’s
a multi-purpose terminal was added to the ore terminal and a small-craft harbour was built to
accommodate increasing recreational and tourism activities in the bay. Development of the port is
ongoing. The growth in industry and urban development has meant an increase in the different
types of discharges into the bay such as fish factory and mariculture discharges, storm water, and
discharges relating to shipping activities such as ballast water and oil spills. Shipping channels in the
Bay are also periodically dredged to ensure unrestricted access to the ore terminal by bulk carriers
and oil tankers.
Sewage discharge is arguably the most important waste product in terms of continuous
environmental impact that is discharged into Saldanha Bay. Sewage is harmful to biota due to its
high concentrations of nutrients which stimulate primary productivity that in turn leads to changes
in species composition, decreased biodiversity, increased dominance, and toxicity effects. The
changes to the surrounding biota are likely to be permanent depending on distance to outlets and
are also likely to continue increasing in future given the growth in industrial development and
urbanisation in the area. These impacts are however manageable, can be monitored and mitigated
so as to cause minimum effects.
Ballast water discharges are by far the highest in terms of volume and also continuous due
to constant and increasing shipping traffic. Ballast water has, through the transport of potentially
alien invasive species to new areas, the potential to impact native species and ecosystem functions,
fishing and aquaculture industries, as well as public health. Ballast water discharges can, however,
be effectively managed and the remit of the International Maritime Organization (IMO) is to reduce
the risks posed by ballast water to a minimum through the direct treatment of the water while on
board the ship, as well as by regulating the way in which ballast water is managed while the ship is at
sea.
Storm water discharges are a seasonal concern and can introduce large volumes of polluted
surface water such as pesticides and trace metals which can in turn be harmful to the environment
and have been shown to exceed permissible concentrations in Saldanha Bay particularly after the
rainy season. Storm water discharges are very difficult to manage and are bound to increase with
increasing urbanization and industrial development in the areas surrounding the Bay.
Dredging in Saldanha Bay has had tremendous immediate impact on benthic micro and
macrofauna, the particle suspension in the water column kills many suspension feeders like fish and
zooplankton. It also blocks sunlight from penetrating the water column and causes die offs of algae
and phytoplankton. The damage caused is reversible in the long term, and although the particle
composition of the settled material is likely to be different, ecological functions as well as major
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