Kangaroo Island Plantation Timbers Pty Ltd Smith Bay Marine Ecological Survey and Assessment Prepared by: David Wiltshire and James Brook SEA Pty Ltd 6th September 2016 Table of Contents SUMMARY 1 Introduction....................................................................................................................... 1 2 Regional setting ................................................................................................................. 3 3 Marine biota of the development site................................................................................ 7 3.1 Methods................................................................................................................................. 7 3.2 Habitat and biota descriptions............................................................................................ 7 3.2.1 Intertidal beach habitat .................................................................................................................... 8 3.2.2 Mixed reef and seagrass habitat (to 10m depth).............................................................................. 8 3.2.3 Seagrass habitat (10-12 m).............................................................................................................. 9 4 Potential impacts and mitigation measures.................................................................... 13 4.1 EPBC listed species............................................................................................................ 13 4.1.1 Introduction................................................................................................................................... 13 4.1.2 Assessment methods ..................................................................................................................... 13 4.1.3 Listed marine species .................................................................................................................... 14 4.2 Direct seagrass loss ............................................................................................................ 15 4.3 Secondary seagrass loss via turbidity effects and erosion .............................................. 16 4.4 Provision of artificial reef.................................................................................................. 17 4.5 Mobilization of sediments by shipping operations.......................................................... 17 4.6 Longshore sand drift.......................................................................................................... 17 4.7 Marine pests ....................................................................................................................... 17 4.8 Land-based abalone aquaculture ..................................................................................... 18 5 Environmental offsets ..................................................................................................... 18 6 Conclusions ..................................................................................................................... 20 7 References........................................................................................................................ 22 List of Appendices Appendix A: Photographs of typical biota and habitats observed during the survey Appendix B: Listed marine species: marine biological assessment List of Tables Table 1. Taxa recorded during the marine survey. Mixed habitat refers to mixed reef, seagrass and sand habitat in depths to 10m. Seagrass habitat refers to sparse Posidonia habitat over rubble and rhodolith substrate at depths of 10-12m. Abundances are expressed as categories: 1 = 1 or 2 individuals or small patches; 2 = 3-10 individuals or patches, 3 = >10 individuals or patches, or a continuous distribution. Common names have not been provided for macroalgae. Regional reef data from the Reef Life Survey program (Reef Life Survey 2016) have been provided for mobile invertebrates. ........................................................................................................................ 10 List of Figures Figure 1. Smith Bay location map........................................................................................................................... 2 Figure 2. The Smith Bay site showing the preliminary design of the infrastructure (source: Aztec Analysis 2016) (scale: the floating wharf is 120 m long)................................................................................................................. 2 Figure 3. Existing habitat mapping for Smith Bay (data source: DEWNR 2016a)................................................. 5 Figure 4. Existing habitat mapping for the central north coast of Kangaroo Island (data source: DEWNR 2016a). Blue dots indicate locations of independent reef survey sites (Reef Life Survey 2015). ........................................ 6 Figure 5. Tracks for kayak-based underwater photo surveys. Orange = November 2015, Purple = August 2016. 8 Summary This report provides a marine ecological assessment of the proposal to develop a deep water wharf at Smith Bay to export logs from timber plantations on Kangaroo Island. The principal ecological issues were considered to be: the loss of seagrass during dredging of the wharf basin and approaches; indirect effects on seagrass communities from increased turbidity and sediment fallout during dredging; and potential impacts on water quality at the adjacent abalone farm during dredging. The main findings of the assessment are as follows: The marine communities at Smith Bay consist of mixed reef and seagrass communities. The seagrasses Posidonia sinuosa and Amphibolis spp. (A. antarctica and A. griffithii) occur in patches amongst rock bottom in depths up to 10m, and continuously, but sparsely, over a mixed substrate of sand, pebble and shell fragment at depths of 10-12 m. With one exception, it is considered that none of the list marine species is at credible risk from the proposed development. The marine listed Ring-backed Pipefish Stipecampus cristatus was found in Posidonia habitat in the area that will be dredged and is therefore at credible risk of being affected. It is considered, however, that the loss of a small amount of pipefish habitat and potentially some pipefish during dredging will have a negligible effect upon their overall population and viability in the area. Construction of the causeway will result in the direct loss of about 0.5 ha of mixed reef and seagrass habitat that supports dense communities of the seagrasses Posidonia sinuosa and Amphibolis spp. Dredging will result in the direct loss of about 9 ha of relatively sparse seagrass consisting mainly of Posidonia sinuosa. The ecological significance of the loss of these seagrass communities will be minor as there is a large amount of similar habitat within Smith Bay and elsewhere along the north coast of Kangaroo Island. Indirect impacts on adjacent seagrass communities through turbidity and sedimentation effects are likely to be relatively minor as silt curtains will be used to ensure that sediment releases during dredging are minimal. Potential effects on water quality at the intake for the abalone farm will be mitigated by moving the intake to a more distant location, and potentially installing additional sand filters at the abalone farm to remove sediment from the intake water. Winnowing of sediments during shipping operations will be minor as the seafloor in the deep water in Smith Bay consists of rubble, coarse sand and shell grit. Effects on biota through increased turbidity and sediment fall-out will therefore be minor. Should investigations reveal longshore drift to be a significant issue at Smith Bay, the first section of the causeway is likely to be replaced by a pier structure to allow sand to move along the shore. BiosecuritySA will be consulted to determine the most appropriate wharf operating procedures (to be documented in a marine pest management plan) to minimize the risk of introducing marine pests to Smith Bay. The loss of seagrass during construction of the causeway and dredging is likely to be offset by supporting programs to reduce nutrient inputs to the local marine environment. Smith Bay Marine Ecological Assessment 1 INTRODUCTION Kangaroo Island Plantation Timbers (KIPT) proposes to develop a deepwater wharf at Smith Bay on the north coast of Kangaroo Island (Figure 1). The wharf will be capable of accommodating 30,000 DWT bulk carrier ships. Although the primary purpose of the wharf will be to export timber from plantations on the island, KIPT proposes to make it available for other shipping uses. The main features of the development at Smith Bay will be: the construction of a causeway to a floating wharf moored approximately 250 m off- shore at a depth of 10 m at its seaward edge; the dredging of a 200 x 50 m berthing pocket adjacent to the wharf to depth of 13 m; the dredging of approaches approximately 600 x 150 m to a depth of 12 m (Figure 2). The on-shore component of the development at Smith Bay will entail constructing several level tiers over an area of approximately 8 ha to store logs, access roads and associated amenities. SEA undertook a preliminary marine ecological assessment of the Smith Bay site and an alternative wharf site at Ballast Head for KIPT in November 2015 as part of an investigation of the advantages and disadvantages of each site (LBW Environmental Projects 2016). Having confirmed that