BEN SCHOEMAN DOCK BERTH DEEPENING Specialist ... - Transnet

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The subtidal rock substratum community - Along the West Coast of South Africa, kelp beds are the dominant communities on subtidal rocky reefs (= Sublittoral zone, Figure 4a). The main species in these beds are the kelps Ecklonia maxima and Laminaria pallida. The more delicate rope-like Macrocystis angustifolia can be found at more sheltered localities (Branch & Griffiths 1988). Below the sublittoral fringe, the inshore zone is generally dominated by small E. maxima plants and supports few animals. At intermediate depths, algal biomass is maximal with large E. maxima plants forming a canopy, beneath which L. pallida and understorey algae grow. Animal species diversity and biomass are, however, still low. Further offshore the kelp plants thin out and give way to a dense faunal community dominated by sea urchins, filter-feeding mussels, sponges and sea cucumbers (Velimirov et al.. 1977, Field et al.. 1980, Branch & Griffiths 1988). Porphyra capensis Cymbula granatina Aeodes orbitosa Gigartina spp. Splachnidium rugosum Gunnarea capensis 2m Typically found on shores Scutellastra cochlear Bunodactis reynaudi Parechinus angulosus Found on more exposed shores Scutellastra granularis Oxystele variegata Ulva spp. 0m Nucella spp. Burnupena spp. ROCKY SUBSTRATA Mytilus galloprovincialis Choromytilus meridonalis Pyura stolonifera Ecklonia maxima -10m Laminaria pallida Epymenia obtusa Aulacomya ater Pentacta doliolum Haliotis midae Jasus lalandii Plagusia chabrus Porifera Pachmetopon blochii Supralittoral Upper Midlittoral Lower Midlittoral Sublittoral Fringe Sublittoral -40m Figure 4a: Typical species zonation patterns on a South African west coast rocky shore (modified after Lane & Carter 1999). 13
Niambia sp. Coleoptera Diptera Tylos granulatus SANDY SUBSTRATA 2m Eurydice kensleyi Excirolana natalensis Pontegeloides latipes Scololepis squamata Donax serra Cumopsis robusta Cerebratulus fuscus Gastrosaccus spp. Bullia digitalis Cunicus profundus Orbinia angrapequensis 0m Virgularia schultzi -2-4m Pectinaria capensis -5-12m Nephtys spp. Lumbrineris tetraura Cirriformia tentaculata Bullia laevissima Ovalipes punctatus INTERTIDAL SURF ZONE BREAK POINT -20-40m Eulittoral Inner Turbulent Zone Transition Zone Outer Turbulent Zone Figure 4b: Typical species zonation patterns on a South African west coast sandy beach (modified after Lane & Carter 1999). In the Table Bay area, kelp beds can be found off the rocky shores at Blouberg and from Mouille Point southwards and around Robben Island. On the eastern side of Robben Island there is a dense Macrocystis bed extending down to a depth of about 10 m (Dr R Anderson, Seaweed Research Unit, MCM, pers. comm.). Field et al. (1980) have surveyed transects across kelp beds at Sea Point (south of Mouille Point) and Melkbosstrand (north of Blouberg), which due to their close proximity are likely to be similar to those found in Table Bay. At both sites, the inshore is dominated by E. maxima, giving way to L. pallida with increasing depth. Kelp densities decline rapidly at a depth of 5-6 and 10 m for Melkbosstrand and Sea Point respectively, which is attributed to relatively high turbidities at these sites. Representative understorey algae in the kelp beds include Bifurcariopsis capensis, Botryoglossum platycarpum, Desmarestia firma, Epymenia obtusa, Gigartina radula, Neuroglossum binderianum, Plocamium corallorhiza, P. maxillosum and Trematocarpus fragilis. Kelp epiphytes include Carpoblepharis flaccida, Carradoria virgata and Suhria vittata. At both sites, but especially at Sea Point, filter-feeders form the largest trophic group, notably the ribbed mussel Aulacomya ater, the holothurians (sea cucumbers) Pentacta doliolum and Thyone aurea, Porifera (sponges) and to a lesser degree the tunicate Pyura stolonifera and barnacles. Carnivores, particularly the rock lobster Jasus lalandii and anemones, are fairly abundant. Rock lobster prey almost exclusively upon the abundant mussels. This is probably again attributable to the turbid waters, providing more food for mussels, which grow faster and provide more food for rock lobsters. Grazers and debris feeders are less common and include the sea urchin Parechinus angulosus, some patellid limpets, the giant periwinkle Turbo cidaris, the abalone Haliotis midae and some isopods and 14
Page 1 and 2: BEN SCHOEMAN DOCK BERTH DEEPENING S
Page 3 and 4: the test organisms. The EC 5 is usu
Page 5 and 6: Turbidity Upwelling Vulnerable Wrac
Page 7 and 8: Another important issue is the poss
Page 9 and 10: 6.2.1.3 Settlement of material susp
Page 11 and 12: 2 METHODOLOGY For the assessment tw
Page 13 and 14: The proposed deepening of the Ben S
Page 15 and 16: 4.3 Cumulative effects Table Bay re
Page 17 and 18: undetectable in 80% of the measurem
Page 19 and 20: 5.1.3 Biological communities The ma
Page 21: Supralittoral fringe (Littorina zon
Page 25 and 26: Midlittoral zone - The intertidal o
Page 27 and 28: Fish - Nearshore and in the sandy b
Page 29 and 30: 2000 at Robben Island revealed furt
Page 31 and 32: Table 2: Common whales and dolphins
Page 33 and 34: Table 3: Site, time, mean count (co
Page 35 and 36: 150000 125000 100000 Kg 75000 50000
Page 37 and 38: sensitive because of its conservati
Page 39 and 40: Schoeman Dock occurred in 1971 (Pro
Page 41 and 42: Table 7: Hydrocarbon distributions
Page 43 and 44: care concentration ranges for cadmi
Page 45 and 46: SS mg/l Boxplot for TSS 80 60 40 20
Page 47 and 48: The mean values calculated above ar
Page 49 and 50: o o possibility of the dredge spoil
Page 51 and 52: The gravel sized component of the s
Page 53 and 54: Table 12a: London Convention Annex
Page 55 and 56: Benthos distributions in Block #1 -
Page 57 and 58: 40 40 30 Site 1A 30 Site 1B % Speci
Page 59 and 60: 2 Cluster Dendrogram and MDS ordina
Page 61 and 62: the well developed ripples in the c
Page 63 and 64: 6 IMPACT IDENTIFICATION AND ASSESSM
Page 65 and 66: Accordingly the potential environme
Page 67 and 68: Impact Assessment Table No Mitigati
Page 69 and 70: are summarised in the table and it
Page 71 and 72: Figure 21b: Predicted number of day
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considered to be low. Further, the
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A A B B B Figure 23a and b: Predict
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dependent on these include the harm
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structures. The apparent lack of su
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Diving birds such as cape cormorant
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Figure 24: The predicted worst case
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Figure 25 depicts the simulation mo
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6.2.3.2 Alteration of benthic biolo
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Impact Assessment Table No Mitigati
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Nature of impact - Turbid plumes of
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Figure 26b: Predicted worst case ex
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Figure 27b: Predicted worst case ex
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suspended sediment concentrations i
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Figure 28a: Dredge spoil dump site
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6.2.3.6 Elevated water column turbi
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The evaluation with mitigation is:
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Figure 29a: Predicted exceedance in
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6.3 Cumulative Impacts The proposed
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Impact summary Table (cont.) Impact
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Impact summary Table (cont.) Impact
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mitigated by ensuring that the Cutt
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operations at Coega Port. Prepared
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Glassom D., K. Prochazka and G.M. B
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Protekon 2006. Port of Cape Town co
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BEN SCHOEMAN DOCK BERTH DEEPENING Specialist ... - Transnet

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