State of the Bay Report 2010-Final - Anchor Environmental

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the spatial differences in community composition in Big Bay could be attributed to particle size composition. Both the abundance and biomass of benthic macrofauna decreased at site BB29 between 2009 and 2010. The results of the sediment analysis revealed that there had been an increase in the percentage mud at BB29 between 2009 and 2010, which may have been related to the dredging conducted in Salamander Bay in 2009. The results of this survey suggest therefore that the dredging conducted in 2009 may have had minor localized impacts on the benthic macrofauna community in the south western region of Big Bay. However, it is not possible to isolate the disturbance that may have lead to this reduction in biomass and abundance as the abundance and biomass of benthic macrofauna was reduced at two other sites (BB20 and BB30) which were further from the dredged site and experienced no increase in the percentage mud content of the sediment. The biomass and abundance of the benthic community at the northern end of Big Bay decreased between 2004 and 2008. The maintenance dredging that took place at the Multi-Purpose Terminal in 2007/8, is most likely the main contributor to this change, however, the effects cannot be isolated from other anthropogenic activities in the Bay given the lack of data between 2005 and 2007. Since 2008, most of the sites at the northern end of Big Bay have shown clear signs of recovery, however, this recovery process has differed in terms of species composition and in the extent of increases in biomass and abundance. These differences are most likely due to the varied current conditions in the bay as well as other localised anthropogenic impacts such as minor dredging events. Langebaan Lagoon Langebaan Lagoon generally supports a much lower abundance and biomass of benthic macrofauna than Saldanha Bay. This may be due to the fast water movements and high levels of tidal variation experienced in the Lagoon. The Lagoon is dominated in terms of abundance by polychaetes and crustaceans and in terms of biomass by crustaceans. The overall biomass in Langebaan Lagoon declined sharply between 1975 and 2004. The reduction in biomass was linked to a loss or reduction in the abundance of many of the taxa present in 1975 (bivalves, polychaete worms, gastropods, echinoderms, and sea-pens). The 2008 survey also indicated that the proportion of filter feeders had been drastically reduced. These results were possibly linked to the dredging that took place at the northern end of lagoon as part of the beach erosion mitigation. The biomass then almost doubled between 2008 and 2009, principally owing to a marked increase in crustaceans (Figure 8.11). The abundance of macrofauna did not increase proportionately suggesting that larger-bodied crustaceans colonised the lagoon between 2008 and 2009. There were further increases in the abundance and biomass of benthic macrofauna between 2009 and 2010. The increase in the overall biomass in Langebaan Lagoon was mainly due to increases in the biomass of polychaetes and echinoderms, while the increased abundance of macrofauna was principally attributed to a marked increase in detritivorous crustaceans. The overall biomass measured in 2010 exceeded that measured in 1975, however, the diversity of taxa has been reduced and crustaceans overwhelmingly dominate the benthic macrofauna biomass. This suggests that the system is in a disturbed state and may have undergone an ecosystem shift. The 2010 survey reveals that the benthic community in the Lagoon is in a state of recovery and that conditions are potentially improving given the increase in the proportion of filter feeder present. State of the Bay 2010: Saldanha Bay and Langebaan Lagoon 168
Average number of individuals per m² Proportion of total number of individuals 3000 2500 2000 1500 1000 500 0 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1999 2004 2008 2009 2010 Big Bay 1999 2004 2008 2009 2010 Big Bay State of the Bay 2010: Saldanha Bay and Langebaan Lagoon 169 Average wet mass per m² Proportion of total biomass 800 700 600 500 400 300 200 100 0 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1999 2004 2008 2009 2010 Big Bay 1999 2004 2008 2009 2010 Figure 8.8. Overall trends in the biomass and abundance of benthic macrofauna in Big Bay as shown by taxonomic and functional groups. Big Bay Polychaeta Crustacea Gastropoda Bivalvia Echinodermata Anchor Environmental Pennatulacea (sea pen) Echiuroidea (Tongue worm) Other SCAVENGER PREDATOR GRAZER FILTER FEEDER DETRITIVORE
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State of the Bay 2010: Saldanha Bay
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TABLE OF CONTENTS Anchor Environmen
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11 BIRDS 234 Anchor Environmental 1
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LIST OF FIGURES Anchor Environmenta
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Anchor Environmental Figure 4.27. O
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Anchor Environmental Figure 7.3. Ch
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Anchor Environmental Figure 9.10. C
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Anchor Environmental Figure 12.1. N
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Anchor Environmental samples were c
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EXECUTIVE SUMMARY Anchor Environmen
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Anchor Environmental matter in the
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Anchor Environmental considered mos
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Anchor Environmental again in 2004,
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Anchor Environmental Populations of
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GLOSSARY Alien species An introduce
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1 INTRODUCTION Anchor Environmental
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2 STRUCTURE OF THIS REPORT Anchor E
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Anchor Environmental complicates ma
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Anchor Environmental observed deter
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Anchor Environmental 4 ACTIVITIES A
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Fish factories Small craft harbour
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Anchor Environmental Aerial photogr
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Anchor Environmental interferes wit
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Anchor Environmental Figure 4.7. Nu
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o Decrease in oxygen concentrations
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Anchor Environmental Upgrades to th
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Anchor Environmental Figure 4.9. A)
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Anchor Environmental (possibly link
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Anchor Environmental Prestedge Reti
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Anchor Environmental the constructi
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Number and types of vessels enterin
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Anchor Environmental is contained b
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Anchor Environmental include the be
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o 33 3’S o 33 10’S Saldanha Bay
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Anchor Environmental (1956) UNDER T
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Free ACtive Chlorine (mg/l) Amonia
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Faecal coliforms (org/100 ml) Chemi
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4.3.7 Storm water Anchor Environmen
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Anchor Environmental sites (concent
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Anchor Environmental Discharges fro
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Anchor Environmental Table 4.9. Det
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5 WATER QUALITY Anchor Environmenta
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Anchor Environmental Stander (1977)
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Anchor Environmental coast, result
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Anchor Environmental likely as a re
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Anchor Environmental Construction o
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Anchor Environmental Table 5.2. Per
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Counts per 100ml of sample Counts p
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Counts per 100ml of sample 10000 10
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5.6 Trace Metal Contaminants in the
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Lead(mg/kg) Mercury (mg/kg) Cadmium
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6 SEDIMENTS 6.1 Sediment particle s
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6.1.2 Sediment Particle size result
Page 117 and 118: State of the Bay 2010: Saldanha Bay
Page 119 and 120: 100% 90% 80% 70% 60% 50% 40% 30% 20
Page 125 and 126: % POC 18 16 14 12 10 8 6 4 2 0 % PO
Page 127 and 128: Percentage Percentage 1.8 1.6 1.4 1
Page 129 and 130: o 33 3’S o 33 10’S Yacht Club B
Page 131 and 132: Figure 6.12. Variation in the conce
Page 133 and 134: The concentrations of metals in sed
Page 135 and 136: concentrations are 56 and 29 times
Page 137 and 138: threshold of 1.2 mg/kg established
Page 139 and 140: Cadmium (mg/kg) 8 7 6 5 4 3 2 1 0 C
Page 141 and 142: Copper (mg/kg) 45 40 35 30 25 20 15
Page 143 and 144: 16000 14000 12000 10000 8000 6000 4
Page 145 and 146: In summary, elevated trace metal co
Page 147 and 148: 6.5 Summary of sediment health stat
Page 149 and 150: 7.1 Long term changes in seagrass i
Page 151 and 152: 7.2 Long term changes in Saltmarshe
Page 153 and 154: Figure 8.1. Benthic macrofauna samp
Page 155 and 156: Table 8.1. Depth at each of the sit
Page 157 and 158: these species usually provide the l
Page 159 and 160: (clustering of similar groups) (Meg
Page 161 and 162: The Big Bay samples BB 25 and BB29
Page 163 and 164: 2007/08 dredging. Other signs of th
Page 165 and 166: Wet mass per m² Wet mass per m² 4
Page 167: Big Bay Crustaceans and polychaetes
Page 171 and 172: Number Individuals per m² Number I
Page 173 and 174: 8.4.2 Abundance Biomass Indices 8.4
Page 175 and 176: and percentage organic nitrogen (PO
Page 177 and 178: Table 8.5. W statistics at all stat
Page 179 and 180: Figure 8.15: Variation in the diver
Page 181 and 182: percentage of mud compared to Lange
Page 183 and 184: Cu (mg/kg) Cd (mg/kg) Ni (mg/kg) Pb
Page 185 and 186: contaminants. Furthermore dredging
Page 187 and 188: areas even 5 months after the clear
Page 189 and 190: Brittle star ( Ophiuroidea spp) Sea
Page 191 and 192: 9.2 Approach and Methodology 9.2.1
Page 193 and 194: cover data for both mobile and sess
Page 195 and 196: 9.2.3 Data Analysis The similaritie
Page 197 and 198: 40%, co-occurring with sponges espe
Page 199 and 200: stands of the kelp Ecklonia maxima
Page 201 and 202: Plocamium spp. Ecklonia maxima Scut
Page 203 and 204: 20 40 A Group 1 B 60 Similarity C G
Page 205 and 206: Percentage Cover 80 70 60 50 40 30
Page 207 and 208: Evenness Shannon Wiener 0.9 0.8 0.7
Page 209 and 210: 2005 2008 2009 2010 Dive School Jet
Page 211 and 212: Table 9.5. Results from the SIMPER
Page 213 and 214: In general, the inter-annual differ
Page 215 and 216: The temporal distribution of M. gal
Page 217 and 218: Consistent with the previous years,
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Saldanha and Langebaan. Results fro
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The average abundance of the four m
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Anchor Environmental Figure 10.5. A
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Anchor Environmental Figure 10.7. A
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Anchor Environmental Within Big Bay
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Anchor Environmental 2008 and 2009
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Anchor Environmental the islands, b
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Anchor Environmental at Saldanha ar
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their main prey species, sardines a
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Anchor Environmental 2009). The eff
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Anchor Environmental attributed to
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Number of breeding pairs 800 700 60
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11.3 Birds of Langebaan Lagoon 11.3
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Anchor Environmental Figure 11.11.
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Anchor Environmental for the gannet
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Taxon Anchor Environmental Occurren
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Taxon Anchor Environmental Occurren
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Anchor Environmental 13 MANAGEMENT
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Anchor Environmental their operatio
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Anchor Environmental concentrations
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Anchor Environmental changes that p
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Anchor Environmental and slight imp
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Birdlife International. 2010. URL w
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Anchor Environmental penguins Sphen
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Anchor Environmental Game, E.T., Gr
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Anchor Environmental Kerwath, S. E.
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Anchor Environmental Moldan, A. 197
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Anchor Environmental Robinson, T.B.
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Anchor Environmental Tunley KL, Att
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