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AusOcean Addendum to the Smith Bay Wharf Draft EIS Response
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Addendum to the Smith Bay Wharf Draft EIS Response

Australian Ocean Lab

(AusOcean)

AusOcean logo

Copyright

Copyright © The Australian Ocean Laboratory Limited (AusOcean) 2019. The information contained herein is licensed under a Creative Commons Attribution 3.0 Australia License (http://creativecommons.org/licences/by/3.0/au).

The information contained in this document has been prepared in response to Kangaroo Island Plantation Timbers Limited (KIPT) Addendum to the Smith Bay Wharf Draft Environmental Impact Statement (EIS) assessment document. The latter is copyright Kangaroo Island Plantation Timbers Limited. Excerpts from the latter are included here under the Fair Dealing provisions of the Copyright Act 1968.


Acknowledgements

AusOcean would like to acknowledge all of its amazing employees, interns, volunteers and partners who made this report possible.

In particular, Catherine Larkin, Lachlan McLeod and Saxon Nelson-Milton deserve a special mention. Special thanks to Trek Hopton and Dave Muirhead for their amazing photos and videos.


Table of Contents

Purpose        4

1.0 Introduction        5

2.0 Marine Ecology        7

2.1 Protected Species        10

2.2 Temperate Coral        11

3.0 Environmental Issues        12

3.1 Noise        12

3.2 Turbidity        17

3.3 Turbulence        19

3.5 Sediment Mobilisation and Seafloor Scour        20

References        26

Appendices        33

Appendix A: Species Inventory        33

Appendix B: Plotting Code        35

Appendix C: Bed Velocity Analysis        36


Purpose

This document has been prepared in response to the Kangaroo Island Plantation and Timber (KIPT) Addendum to the Smith Bay Wharf draft Environmental Impact Statement (EIS), dated October  (2019).

This document seeks to remedy inaccurate and/or misleading statements presented in the Addendum through a scientific and evidence-based assessment of the impact of the proposed development, based both on first-hand observations and the best-available science.

This document was prepared by the Australian Ocean Lab (AusOcean). AusOcean is a South Australian-based non-profit organisation, registered on the Commonwealth’s Register of Environmental Organisations (REO) and with the Australian Charities and Not-for-profits Commission (ACNC). AusOcean receives no public funding. AusOcean’s ABN is 34617043722.


1.0 Introduction

Kangaroo Island Plantation Timber (KIPT) released the Addendum to the Smith Bay Wharf Draft Environmental impact statement (EIS) in October 2019. In response, AusOcean returned to Smith Bay in November 2019 to conduct further marine ecological surveys[1]. In previous assessments undertaken in December of 2018 and February of 2019 sites were selected to encompass both the eastern and western sides of the bay and deeper waters located more centrally (see Larkin, 2019). In doing so, a variety of locations were surveyed to assess the heterogeneity of habitats and species throughout the bay.

Sites surveyed in November were strategically selected to assess the potential implications of the revised design features put forward by KIPT on the marine ecology of Smith Bay (Table 1). Notably, the construction of a suspended deck jetty, connecting to a floating wharf approximately 650m offshore. Locations at the berthing area, approach, exit and jetty were subject to additional surveys to assess the potential consequences on marine communities by construction, as well as direct and indirect impacts from vessel movements. Of particular interest was a site identified by SEA Pty Ltd as an area of topographical interest located in the vessel approach trajectory identified in the Addendum as site S31 (Appendix C2). This site however, was only surveyed using camera drops, therefore it was included in our surveys to assess its ecological importance.

Smith Bay and indeed, the entire north cost of Kangaroo Island forms part of the wider Great Southern Reef (GSR) spanning the entire southern coastline of the Australian continent. Many of the species found within Smith Bay and the wider GSR utilise temperate reef habitat and adjoining inter-reef habitats such as seagrass meadows and sponge ‘gardens’. These intermediary habitats facilitate connectivity among reefs and act as important nursery grounds for many species. Unfortunately, local stressors such as intense coastal developments are having profound effects on the health and resilience of habitats throughout  the GSR.

Smith Bay’s marine environment exhibits high species richness and endemism supporting an abundance of emblematic and threatened species with high conservation value. Six protected species from the Syngnathidae family have been noted in Smith Bay. Including both the Weedy sea dragons (Phyllopteryx taeniolatus) and Leafy sea dragons (Phycodurus eques) which were noted at a site located within the vessel approach. These species  are  susceptible to major sediment disturbance from propeller wash and the consequent increase in turbidity. Furthermore, two species of temperate coral namely, Coscinaraea mcneilli and Plesiastrea versipora were sited in numerous locations throughout the bay. These corals are rare in South Australian waters, with their relatively widespread presence on the island likely due to the undeveloped coastline which provides a refuge from threats such as water pollution.

This document describes how the proposed development would undeniably damage the marine environment of Smith Bay. Numerous evidence-based studies that demonstrate why species may lack the ability to simply ‘move away’ from a perceived threat, such as noise and/or turbidity, have been provided and analysed throughout the document. Hence, potential damage to marine fauna is likely, particularly for benthic invertebrates that are unable to move and species more susceptible to environmental perturbations, such as those from the Syngnathidae family. Anthropogenic noise generated during construction and ongoing port use is not only a threat to individuals but may have implications on the health and service functions of the entire ecosystem. We suggest that any potential damaging impacts to Smith Bay’s ecosystem both ecologically and biologically should be assessed in its entirety and be encompassing of all resident species.

Furthermore, we raise numerous new concerns in relation to the water quality impacts assessment, in particular, the sediment sampling and operational propwash modelling of the revised design. Firstly, baseless assumptions that old sampling data would be sufficient to describe the new location, secondly, an overestimated median grain diameter to describe sediment over the entire location, thirdly, invalid justification for use of a large median grain diameter, and finally selected vessel characteristics used in modelling that are not conservative.

All of this considered, we retain our earlier recommendation that Smith Bay is an inappropriate place for the KIPT, or any, port.

2.0 Marine Ecology

Smith Bay and indeed, the entire north coast of Kangaroo Island forms part of the wider Great Southern Reef (GSR) spanning the entire southern coastline of the Australian continent (Bennett et al. 2015). The GSR is one of the most pristine and unique temperate reefs in the world and has been recognised as Mission Blue’s newest Hope Spot in recognition of the reef’s exquisite, raw beauty and immensely rich biodiversity (Mission Blue, 2019). Many of the species found on the GSR utilise temperate reef habitat and adjoining inter-reef habitats such as seagrass meadows and sponge ‘gardens’ (Bennett et al. 2015). These intermediary habitats facilitate connectivity among reefs (Vanderklift & Wernberg 2008) and act as important nursery grounds for many species (Jenkins & Wheatley 1998). Unfortunately, local stressors are having profound effects on the health and resilience of the GSR. For example, kelp forests  have undergone widespread decline and loss adjacent to intense coastal developments as a result of localised pollution (Bennett et al. 2015). These losses are likely to continue over the next century with local declines accumulating to eventually coalesce as regional impacts (Bennett et al. 2015). The high diversity and endemism of the GSR make it globally unique.

According to the State of the Environment Report (EPA 2018) the South Australian marine environment is subject to a diverse range of anthropogenic influences.  Human pressures include, but are not limited to, coastal  pollution, habitat modification, disturbance of native species and incursions of pests and diseases. These impacts coupled with the effects of climate change are exacerbating the pressures imposed on these fragile systems. Current population trends for coastal and marine native fauna are worsening with declines in parts of the state with the highest population and development (EPA 2018).

Smith Bay’s marine environment exhibits high species richness and endemism supporting an abundance of emblematic and threatened species with high conservation value. This is due in part to the heterogeneous ecology that provides complex habitat for a myriad of species including fishes, sponges, bryozoans, echinoderms and molluscs. Over the course of our surveys, 60 species of fish and 35 species of invertebrates were noted within surveys, comprising 1778 individuals (1460 fish and 318 invertebrates) an additional 11 species of fish and 9 species of invertebrates were sited outside surveyed transects (see Appendix A for entire species inventory). Of these, five species noted by AusOcean and one by SEA Pty Ltd. are protected under the Australian Commonwealth Environmental Protection and Biodiversity Conservation (EPBC) Act (1999). In addition, several species of conservation concern were noted as described by the Conservation Council, Reef Watch Feral or Imperil program (Reef watch 2019).

Due to the recent changes in wharf design, habitats of particular interest are those that will be either directly or indirectly impacted by jetty construction and ongoing wharf use located now 650m offshore. Therefore, sites surveyed in November 2019 were selected to reflect the amendments made to project design (Table 1). Of particular interest is the presence of reef habitat located in the vessel approach that is home to several species of protected Syngnathidae including Weedy sea dragons (Phyllopteryx taeniolatus) and Leafy sea dragons (Phycodurus eques). This site was identified by SEA Pty Ltd as an area of ‘topographical interest’, however, was assessed using camera drops, as opposed to scuba surveys. We therefore included it in our surveys to assess its ecological importance. These unique pockets of varied reef topography provide necessary habitat and shelter for a myriad of fish and invertebrate species, including those that are protected (Figure 1). These species will be affected both during wharf construction and ongoing wharf use as a result of shipping movements. The full extent of this reef is unknown however we can confirm its presence in numerous locations (Figure 2).

Figure 1: Reef habitat located at site 4 (left) and site 16 (right).

Table 1: Sites, coordinates and number of transects for November 2019 dives sites.

Site no.

Site

Lat (deg)

Lng (deg)

No. Transects

11

Exit

-35.58423

137.424

1

12

Berthing Area West (BAW)

-35.58525

137.42563

1

13

Jetty

-35.58653

137.4261

1

14

Berthing Area East (BAE)

-35.58529

137.42772

2

15

Approach

-35.58385

137.4294

1

16

S31

-35.58478

137.43122

2

Figure 2: Map of survey locations.


2.1 Protected Species

Six protected species from the Syngnathidae family have been noted in Smith Bay. Namely, Wide bodied pipefish (Stigmatopora nigra), Spotted pipefish (Stigmatopora argus), Mother of pearl pipefish (Vanacampus margaritifer), Ringed back pipefish (Stipecampus cristatus), Weedy sea dragon (Phyllopteryx taeniolatus) and Leafy sea dragon (Phycodurus eques). These species are protected under the Australian Commonwealth Environmental Protection and Biodiversity Conservation (EPBC) Act (1999).

Smith Bay has the potential to be a Syngnathid hotspot for numerous reasons:

  1. Six species have already been recorded which suggests that further taxa are likely to be present.
  2. Habitat within Smith Bay is highly heterogeneous providing a range of seagrass, reef and sponge habitat which supports a diverse assemblage of fish species. Additionally, Smith Bay is located in close proximity to other known hotspots such as Pelican Lagoon.
  3. Further species await discovery and a location such as Smith Bay which has never been trawled is a place where rare and potentially new species may have survived (D Muirhead, personal communication, 18 December).

Protected species of Smith Bay will be exposed to a myriad of risks stemming from the construction and ongoing use of the wharf, namely noise, turbidity and turbulence. These are discussed in further detail throughout the report. It is important to note the impacts addressed throughout this report are by no means exhaustive. There are a plethora of associated risks likely to impact these vulnerable species and surrounding environs, both known and unknown.

Figure 3: Leafy sea dragon (Phyllopteryx taeniolatus) (left) and Weedy sea dragon

(Phyllopteryx taeniolatus) (right) noted at site 16.

2.2 Temperate Coral

Throughout AusOcean’s surveys two species of colony forming corals, namely Coscinaraea mcneilli, and Plesiastrea versipora were sighted at several locations throughout Smith Bay, including site 16 of the most recent surveys by AusOcean (Figure 4). Numerous sightings suggest there may be additional colonies yet to be discovered within the bay.

Baker et al. (2013) has described the temperate coral Plesiastrea versipora as a species of conservation interest on northern Kangaroo Island. Although this species is not currently considered threatened on a global scale, there may be localised threats for populations residing in shallow water systems due to sedimentation of reefs, nutrient enrichment due to coastal developments and physical damage caused by destructive fishing practices (Baker et al. 2013). It has been suggested by Baker et al. (2013) that the undeveloped coastline of northern Kangaroo Island (as opposed to eastern coast of Gulf St. Vincent for example) provides a refuge for these species from threats such as water pollution. Hard corals such as P. versipora are very slow growing in temperate waters with rates of less than 1cm per year (Burgess et al. 2009). For example, research by Burgess et al. (2004) has dated the base of a 24cm P.versipora core in the Spencer Gulf to 151 years. Furthermore, an additional 6 colonies of coral in the South Australian gulfs with age estimates ranging from 90-320 years were dated using various methods of ageing (Burgess et al. 2004). Baker et al. (2013) suggest that large old colonies of P. versipora are rare and it is considered likely that such colonies below 10m deep have been removed in the gulfs region by trawling, which has occurred since the 1960’s. 

Figure 4: Green coral (Plesiastrea versipora) (left) noted at site 4 and  McNeill’s coral (Coscinaraea mcneilli) (right) noted at site 16.

3.0 Environmental Issues

This section raises direct concerns with the following statements contained within the Addendum to the Smith Bay Wharf Draft EIS.


3.1
Noise

  1. As noted in the Draft EIS, damage to the hearing of marine fauna would be considered unlikely as the normal behavioural response to loud noise would be to move away. Behavioural changes in response to noise are expected to be temporary and ecologically inconsequential as Smith Bay is not known to provide important feeding or breeding habitat.
  2. The Draft EIS assessment concluded that without mitigation, the overall risk of adverse noise effects on the relevant marine species is low.

According to the World Health Organisation (2011) human induced (anthropogenic) noise is recognised as a global pollutant and is characterised as one of the most harmful forms. Research surrounding the effects of noise pollution has primarily centered around marine mammals. In recent times however, the implications on fish and invertebrates are being increasingly recognised (Weilgart 2018). This is an important consideration because fishes and invertebrates underpin the food web for marine mammals, reptiles, seabirds and humans (Hawkins & Popper 2016). According to Slabberkoon et al. (2010) all fish studied to date are able to hear sounds and that increasing numbers of invertebrates are able to detect sound and/or vibration and respond to acoustic cues (Simpson et al. 2011). It has been suggested that fish and invertebrates use sound in numerous ways, comparable to marine mammals and terrestrial vertebrates (Hawkins & Popper 2017). This includes communication with conspecifics, avoiding predators, seeking prey, locating appropriate habitats, and orientating with respect to environmental features (Hawkins & popper 2017).

As outlined in the EIS (Appendix N p.34) fish with swim bladders (most teleost fish) are much more susceptible to trauma, compared to those without (chondrichthyes). However, underwater noise predictions and threshold distances were not included for either fish with swim bladders or invertebrates. Underwater pile driving and its impact on fish and invertebrates are adequately discussed in an assessment made by McAuley & Kent (2008) in response to a proposed wharf development. It therefore remains unclear as to why these assessments have not been included in either the EIS or Addendum. Although there are discussions surrounding the usefulness of behavioural audiograms in only a select number of fish species, these effects and risks should be adequately addressed.  Even though many of the fishes and invertebrates present in a system may not be afforded special conservation designation as a species, they may be especially important components of local ecosystems (Hawkins & popper 2017). Any potentially damaging impacts to Smith Bay’s ecosystem both ecologically and biologically should be assessed in its entirety and be encompassing of all residing species. Of particular importance are individuals that may be especially vulnerable to noise exposure and those that play an important ecological role within local biological communities (Hawkins & Popper 2017).

Noise is known to have wide ranging, adverse effects on an individuals behaviour, anatomy, physiology and development (Weilgart 2018). An organism's response to sound is dependent on a variety of factors such as tolerance, distance, degree of exposure and the nature of the source (Hawkins & Popper 2017). Figure 5 details a number of possible responses to sound. Furthermore, a detailed outline of the potential effects of anthropogenic noise is outlined in Table 2, as derived from Hawkins & Popper (2017).

 

Inserting image...Figure 5: Potential effects of sound at different distances from a source (Hawkins & Popper 2017).

Table 2: Potential effects of anthropogenic sound on animals. From Hawkins & Popper (2017).

Death

Either immediate mortality or tissue and/or physiological damage that is sufficiently severe that death occurs some time later due to decreased fitness. Mortality has a direct effect upon animal populations, especially if it affects individuals close to maturity.

Physical and/or Physiological Effects

Tissue and other physical damage or physiological effects, that are recoverable but which may place animals at lower levels of fitness, may render them more open to predation, impaired feeding and growth, or lack of breeding success, until recovery takes place.

Impaired Hearing

Short - or long-term changes in hearing sensitivity (temporary threshold shift - TTS or permanent threshold shift - PTS) may, or may not, reduce fitness and survival. Impairment of hearing may affect the ability of animals to capture prey and avoid predators, and also cause deterioration in communication between individuals; affecting growth, survival, and reproductive success.

Masking

The presence of man-made sounds may make it difficult to detect biologically significant sounds against the noise background. Masking of sounds made by prey organisms may result in reduced feeding with effects on growth. Masking of sounds from predators may result in reduced survival. Masking of spawning signals may reduce spawning success and affect recruitment. Masking of sounds used for orientation and navigation may affect the ability of fish to find preferred habitats including spawning areas, affecting recruitment, growth, survival and reproduction.

Behavioural Responses

Changes in behaviour may take place in a large proportion of the animals exposed to the sound, as such responses may occur at relatively low sound levels. Some of these behavioural responses may have adverse effects. Displacement from preferred habitats may affect feeding, growth, predation, survival and reproductive success. Changes in movement patterns may affect energy budgets, diverting energy away from egg production and other vital functions. Migrations to spawning or feeding grounds may be delayed or prevented, with detrimental effects upon growth, survival and reproductive success. Prevention of recruitment and settlement in preferred habitats may affect colonization and population size in any area exposed to high levels of noise.

Kunc et al. (2016) showed that noise impacts on behaviour at the individual level such as compromised communication, feeding, orientation, parental care, prey detection and increased aggression can have implications at the community level through less group cohesion, avoidance of important habitat, fewer offspring and higher death rates (Figure 6). Similarly, noise impacts on physiology can cause poor growth rates, low reproductive rates and decreased immunity (Weilgart 2018). While some individuals may recover from physiological or behavioral impacts, other serious injuries such as changes to DNA or genetic material or injury to vital organs are irreversible (Kight & Swaddle 2011). These collective impacts, reversible or not, can have broad ramifications on ecosystem functioning, potentially altering the population biology (the health and resilience of various populations) and ecology (the interaction and coexistence of multiple species) (Kunc et al. 2016). Williams et al. (2015) suggest that non injurious effects can still accumulate to have population level impacts mediated by a range of factors including physiological. This is supported by Peng et al. (2015) who conclude that noise pollution is not only a threat to individuals, but may also have implications on the health and service functions of entire ecosystems.

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Figure 6: The effects of anthropogenic noise on individuals’ anatomy, physiology and/or behaviour, resulting in effects at the ecological level (Kunc et al. 2017).

Often, the effects of noise have been oversimplified by suggesting that species are either sensitive and will abandon an area or are not and will remain (Francis & Barber 2013). Researchers advise that it should not be automatically assumed fish will leave a noisy area and thus avoid harmful exposures for several reasons (Aguilar de Soto 2016). It is not uncommon to observe a typical “fright” response or to freeze in place (Popper 2003), or individuals may not be able to escape because they are disoriented from the noise effects on their sensory systems (Aguilar de Soto 2016). Furthermore, some species are territorial and others have small home range sizes and cannot move quickly enough. For example, species from the Syngnathidae family (pipefish, seadragons and seahorses) have life history traits that make them particularly susceptible to decline (Foster & Vincent 2004; Martin-Smith & Vincent 2006). Studies show that most individuals in common with leafy seadragons, have limited home range sizes of <1 ha (Sanchez-Camara & Booth 2004). This may make it difficult to move away from a perceived threat, particularly if they are residing in areas of fragmented habitat. Furthermore, damage to hearing structures can worsen over time, even after the noise has ceased, sometimes becoming most pronounced after 96 hours post-noise exposure with temporary hearing loss lasting months (Weilgart 2018).

Human activities that involve direct contact with the sea bed such as pile driving, which produces radiating particle motion waves, can impact bottom dwelling animals (Roberts et al. 2015). Studies have shown ecological services such as water filtration, mixing sediment layers and bioirrigation (fundamental nutrient cycling processes on the seabed) can be negatively affected. Researchers utilised a semi-open field experiment to examine the effect of impact pile driving on clearance rates in mussels. Clearance rate, the rate at which filter feeders sift out suspended particles from the water, is a reliable indicator of feeding activity in mussels (Weilgart 2018). Hence, observed increased feeding rates may be a sign of mussels coping with stress and the higher metabolic demand this requires (Spiga et al. 2016). In addition Roberts et al. (2015) found clear behavioural changes in mussels, mainly valve closure. The results indicate that vibration through activities such as pile driving is likely to impact the overall fitness of individuals and mussel beds due to disruptions in valve periodicity which can have ecosystem and commercial implications.

In addition to sounds of relatively short exposure, such as those produced during pile driving, more moderate noises that occur over longer durations such as those produced by vessels have the potential to impact much larger areas and therefore have wider implications on inhabiting marine fauna (Slabberkoon et al. 2010). Studies that investigated boat noise and its effect on local fish species found that by raising ambient noise by 40dB, detection distance of other fish sounds can be reduced by 100-fold depending on the species (Codarin et al. 2009). Other effects include antipredator behaviour (La manna et al. 2016; Simpson et al. 2016; McCormick et al. 2018; Wale et al. 2013), foraging and feeding (Magnhagen et al. 2017; Bracciali et al. 2012; McLaughlin & Kunc 2015; Payne et al. 2014), attention (Purser & Radford 2011; Chan et al. 2010; Voellmy et al. 2014), schooling behaviour (Sarà et al. 2007; Mueller-Blenkle et al. 2010) and perhaps the most serious impact, survival and reproduction, which can have consequences at the population level (Nedelec et al. 2017; de Jong et al. 2018; Krahforst 2017). Wale et al. (2016) demonstrated the effects ship noise playbacks can have on mussels. Results showed significantly higher breaks in the DNA in cells of noise exposed mussels. Algal clearance rates were also lower and oxygen-consumption rates higher, indicating stress. These impacts can cause reduced growth, immune response and reproduction. Lower algal clearance rates imply that important ecological services such as water filtration could not be performed (Wales et al. 2016). Further research by André et al. (2011) found that experimental exposure to low sound frequencies of two species of squid, one species of cuttlefish, and one species of octopus resulted in massive acoustic trauma.

To oversimplify the ramifications of noise pollution and suggest that species have the ability to simply ‘move away’ is inadequate. We provide numerous evidenced-based studies that demonstrate why species may lack this ability. For this reason, potential damage to marine fauna is likely, particularly to benthic invertebrates that are unable to move. Moreover, proposing that noise-based behavioural changes are expected to be temporary and ecologically inconsequential contradicts relevant research. Numerous studies clearly outline the potential behavioural changes and significant implications at the population level.


3.2 Turbidity

Turbidity is the relative measure of clarity caused by suspended particles in the water column. It is known to affect key evolutionary processes related to visual stimuli and olfactory cues in many species of fish (Higham et al. 2015). Site 16, an ecologically diverse location containing species of high conservation significance, lies directly beneath the proposed trajectory of ships approaching the wharf. At a depth of 15m, the site is susceptible to major sediment disturbance from propeller wash (see section 3.5) and a consequent increase in turbidity.

5 species of Syngnathids, all of which are protected (EPBC Act 1999), have been sighted within Smith Bay. They are a family of highly visually oriented fish and as such their sexual selection is largely determined by visual cues (Rosenqvist and Berglund 2011). Adaptive mate choice requires these cues to be communicated clearly by both receiver and sender. Those organisms that rely solely on visual stimuli for mate choice can face decreased levels of fitness for both sexes, as a consequence of impaired signal transmission (Sundin et al. 2010). This in turn, can negatively affect population viability. Sundin et al. (2010) noted the effects of turbidity in a sex role-reversed broad-nosed pipefish, Syngnathus typhle, where male mate choice was indeed altered by turbid water. As with most species of fish, colours and markings are factors in mate choice, as is body size, an important trait in sexual selection which directly relates to fitness (Sundin et al. 2010). S. typhle males always chose larger females in clear water, however turbidity hindered their vision resulting in decreased time assessing potential mates and no preference in relation to quality/size of the females. Furthermore the pipefish did not appear to use olfactory cues for mate choice, making visual incentive the sole motivator for sexual selection. Similar results in other species of fish have been found (Moyaho et al. 2004; Heubel and Schlupp 2006; Engström‐Öst and Candolin 2007).

The feeding behaviour of fish is another key process susceptible to change in turbid water (Kellog and Leipzig-Scott 2017). For many species of teleost fish, there is a strong correlation between visual predation and illuminance of the immediate underwater environment (Felício et al. 2006). The majority of syngnathids are diurnal feeders, with only two species of seahorse and one species of pipefish recorded as feeding nocturnally (Manning et al. 2019). Such a direct relationship between feeding and light availability suggests a drastic change in turbidity will result in drastically disturbed feeding regimes. While it is true some fish are able to use both visual and olfactory cues in their foraging efforts, this is not the case for the syngnathids, which are highly adapted visual hunters (Manning et al. 2019). Their specialised eyes are evolved to seek out live, mobile prey, rich in carotenoids (Collin and Collin 1999). Coupling the impacts of disturbed feeding regimes with reduced visibility for predation could have detrimental effects on survival and reproduction.

Two species of temperate coral identified in Smith Bay (see section 2.2) have the potential to be negatively affected by turbid water and resuspension of benthic sediment. Turbidity and suspended sediment concentrations (SCC) are known to limit ambient light availability, thereby hindering photosynthesis of the coral’s endosymbiotic algae (Pollock et al. 2014; Macdonald 2015). Being heterotrophic feeders, excess sedimentation can clog feeding apparatus, inhibiting feeding efficiency and further contributing to a decrease in overall energy intake (Bessel-Browne et al. 2017). Furthermore there is evidence that suggests sediment and turbidity are directly related to disease prevalence in corals. Pathogens such as silt-associated bacteria can be carried by disturbed sediment onto nearby corals, contributing to necrosis and other health issues (Pollock et al. 2014). Temperate coral colonies are rare and of ecological interest. Those located within the vicinity of wharf construction and underlying vessel movements will be particularly susceptible to damage or destruction.


3.3
Turbulence

Panamax vessels with a draft of up to 11.75m can cause significant turbulence in the water column. Those organisms and surrounding habitat which are not immediately destroyed via contact with vessels and propellers, have the potential to become severely displaced or experience alterations in feeding and behavioural mechanisms (Higham et al. 2015)

Syngnathids are particularly susceptible to turbulence issues. Compared to most species of teleost fish, syngnathids are weak swimmers. They move delicately and stealthily through rapid oscillations of the pectoral and dorsal fins, rather than thrusting through water using muscular caudal fins (Consi et al. 2001; Ashley-Ross 2002; Neutens et al. 2017). It is a likely scenario that any syngnathid caught in turbulence from propeller wash will be destroyed due to their inabilityto swim away. Those syngnathids that are able to escape physically unscathed, still face danger from disorientation due to their limited home ranges (Sanchez-Camara and Booth 2004). Furthermore, bony fish have sensitive swim bladders that, when under stress, are susceptible to damage. Improperly functioning swim bladders fail to adequately maintain buoyancy, resulting in the eventual death of the fish.

Turbidity as a consequence of turbulence is well documented, however the effects of turbulence on the fitness of organisms through altered zooplanktonic interactions at the trophic level is less known (Iversen et al. 2009). Boat generated turbulence has a myriad of effects on copepods (Bickel et al. 2011), small crustaceans of extreme importance in many aspects of marine ecology, such as the food web. They are one of the key primary food sources for many species of fish, including seadragons and pipefish (Collin and Collin 1999). Bickel et al. (2011) describe changes in behaviour, physiology and most notably, the high mortality rates of copepods attributed to boat generated turbulence. Disruptions at any trophic level can lead to drastic alterations in the food chain, many of which are catastrophic or have largely unknown effects. As noted by KIPT in the addendum, up to 10 vessels per day may enter Smith Bay during construction, with the possibility of creating frequently turbulent conditions. The potential for negative impacts, either direct or indirect, affecting organisms and the ecosystem as a whole raises cause for concern.

3.5 Sediment Mobilisation and Seafloor Scour  

From the Addendum to the Smith Bay Wharf Draft EIS, a comment is made based upon BMT’s water quality impacts assessment of the revised design: “The results also confirm that ship movements would result in only very minor effects on water quality in Smith Bay that would be confined to the immediate vicinity of the pontoon.” (Environmental Projects 2018, pg 15); it could be argued however that BMT’s updated water quality assessment does not adequately adjust for the new design. BMT states that the “operational propwash modelling assessment undertaken for the Draft EIS (BMT 2018a) was updated for the revised KI Seaport design” (BMT 2019, pg4), however, there is no indication that new sediment samples have been collected to parameterize the updated location. It can only be assumed that the revised model has re-used sediment characteristics found from the original sampling sites.

Figure 7 outlines the sediment sampling locations relative to the old and new designs. It is clear that the original sampling sites do not extend adequately northward to describe the revised berthing and approach/departure locations. The assumption that sediment characteristics are consistent across the old and new areas is unfounded; suggested by Figure 8, showing median sediment diameters to be heterogeneous across sampling sites. Assuming this heterogeneity continues northward, it is possible that there are locations of particular susceptibility to suspension and mobilisation that have not been accounted for in modelling; one such location being Site 16, a site of ecological significance (see section 2.1).


Figure 7: Comparison of old and new wharf design from
(Environmental Projects 2019) with an overlay of approximate dredge
area and sediment sample locations.

Not only do the original sampling sites fail to describe sediment characteristics of the new wharf area, it is also questionable as to how well the original model accounts for the clear diversity in sediment diameters as to be necessarily conservative within the analysis. While parameterisation of shipping to be involved is cautious i.e. adopting characteristics of Panamax Class (largest vessel to be used at the Wharf), full power over acceleration/deceleration and large acceleration/deceleration segments, the choice of median grain size and justification is unusual. BMT states that “A median grain size was applied, corresponding to the maximum value from the geotechnical assessment (COOE, 2017) which maximises the friction coefficient.” (BMT 2019, pg83), but according to the analysis documents made available from COOE (2018), the maximum grain size was not 0.5mm, as some diameters reported were up to 19mm. In any case, the justification provided is unusual. It’s unclear why a maximum grain size was chosen in the first place; susceptibility to resuspension and transport is negatively correlated to grain size regardless of increased frictional coefficient, as demonstrated by equation 1 from Van Rijn (2013) giving critical suspension velocity.

        (1)

This equation provides critical suspension velocity (bed velocity at which particles become suspended) as a function of grain diameter, assuming relative density and water depth are constant. If this relationship is plotted, it is clear that the critical velocity decreases with a decrease in grain diameter, as shown by figure 9. Put simply, the smaller sediment grain size, the more readily it is suspended by bed velocities. It is therefore unexpected that a maximum grain size was chosen as a median if the intention was to be conservative.


Figure 8: Sediment sampling locations with median particle size (mm) indicated (COOE 2017).

Median grain diameters for each site have been extracted from the ALS (2017-2018) analysis results, summarised and overlaid on the site map in Figure 8. Information on sites however is deficient, as the analysis results for 4 sites, namely, SB3, SB4, SB9 and SB11 have not been included in the COOE (2019) report. No explanation for their absence has been provided. Nonetheless, it is still obvious that median grain diameter varies significantly from site to site, and for the most part is much smaller than 0.5mm, with the minimum median diameter in the included data being .118mm (ALS 2017). A conservative analysis would have adopted the smallest found median diameter, or used the median sediment diameter over all sites, and then applied some factor of safety. Adopting a median grain diameter larger than the actual median would result in an analysis that would undoubtedly underestimate sediment mobilisation and transport.


Figure 9: Plot of equation 1 (see Appendix B for plotting code).

A concern besides the aforementioned assumptions on sediment grain size is the chosen set of vessel characteristics used for modelling; the main factor in determining resulting bed velocities besides water depth. Table 3 summarises vessel characteristics from the BMT (2019) hydrodynamic analysis, for which no origin or justification of these values is provided. Interestingly, they do not align well with typical vessel characteristics provided by MAN Diesel & Turbo (2013) visible in Table 3; SMCR power for vessels of similar size is considerably larger than the adopted value. For the BMT analysis to be conservative, a vessel resulting in maximum bed velocity while satisfying the imposed dimensional limits should have been chosen, but the analysis performed (Appendix C) shows that this is not the case. Two typical panamax vessels satisfying the dimensional constraints have been found to impose higher maximum bed velocities than the vessel adopted by the BMT modelling. This indicates that the BMT modelling has not been sufficiently conservative; there are clearly other vessels that could be used with this wharf that will have a greater influence on sediment mobilisation. Proponents of the EIS may argue that vessels with greater SMCR power than that of the selected will not be used at the wharf, but the EIS clearly states that the wharf will accommodate “Panamax vessel of up to 60,000 deadweight tonnes (DWT) and a draft of up to 11.75 metres.” (Environmental Projects 2019, pg51). Either the BMT analysis has not been sufficiently conservative, or statements regarding vessel limits are misleading.

Table 3: Vessel characteristics and resulting max seabed velocity at
Depth 15m corresponding to Site 16 for vessels from BMT and
AusOcean analysis’ (vessel characteristics for AusOcean analysis
are typical for vessels in this class (MAN 2013)).

Vessel

1, BMT

2, AusOcean

3, AusOcean

Class

Panamax

Panamax

Panamax

DWT (tonne)

63,000

38,100

30,800

Draft (m)

11.6

11.3

10.7

LOA (m)

200

246

211

Breadth (m)

32.3

32.2

32.2

SMCR Power (kW)

8,990

31,300

25,000

Cruise Speed (kts)

23[2]

23.5

22.5

Prop Diameter (m)

6.5

8.48

8.03

Prop Speed (Hz)

2.05

1.75

1.74

Max Seabed Velocity (m/s)

8.94

11.12

9.63


Not only does the BMT modelling appear flawed in itself, it also only addresses effects of sediment suspension and transport on general water quality throughout Smith Bay, and in particular the impact this may have on Yumbah’s water intake, however, it does not address the extent of direct damage operational propwash may have on sites located in the berthing area and the approach/departure zones. Although substrate in the berthing area is rubbly, and less prone to resuspension, sites such as site 16 were observed to possess fine sandy substrate. It is said in the original BMT (2018, pg 83) modelling report: “The approach and departure patterns of the vessel are operator influenced and subject to high variability.”. Based on previous marine surveys, there is in all likelihood, sites of similar ecological significance to Site 16. Any such site will be subject to detrimental effects, both direct and indirect, as a consequence of these highly variable vessel approach/exit trajectories. Calculated maximum seabed velocity (stationary to thrust required for cruise) of the BMT modelled vessel is 22 times the critical suspension velocity of grains with .5mm size at 15m depth; the same depth of site 16. There is no doubt substrate, vegetation and organisms would be ripped apart with velocities of this magnitude. There is clear evidence that turbulence and turbidity have detrimental effects on organisms, as explored by Sections 3.3 and 3.2 respectively.

To summarise, the revised BMT hydrodynamic analysis is problematic on multiple fronts:

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Appendices

Appendix A: Species Inventory

*Total and FOO includes North Central and North where no formal survey transects were undertaken.

Appendix B: Plotting Code

The following code was used to create the plot of equation 1 i.e. critical suspension velocity vs grain diameter.

# Clean up environment.
clear all
close all
clc

# Define some const parameters.
h =
15                  # Water depth (m).
g =
9.81                # Acceleration due to gravity (m/s/s).
rho_w =
1000            # Water density (kg/m^3).
rho_s =
1602            # Sediment (sand) density (kg/m^3).
v =
1.3*(10^-6)         # Water kinematic viscosity coefficient (10degC) (m^2/s).
d =
.0001:0.00001:0.0005; # Range of diameter values (m).
# Relative density
s = rho_s / rho_w

# Dimensionless sediment
size                                                 
d_star = d.*(((s
-1).*(g/(v.^2))).^(1/3));

# Critical dimensionless shear stress                          
theta_cr =
.3./(1+d_star)+.1.*(1-exp(-.05.*d_star));

# Critical suspension velocity (m/s)                
v_cr =
5.75.*log10((12.*h)./(6*d)).*((theta_cr.*(s-1).*g.*d).^.5);

# Create plot.
plot(d,v_cr)
title("Critical Suspension Velocity vs Grain Diameter")
xlabel("Median Grain Diameter, D_{
50} (m)")
ylabel("Critical Suspension Velocity, U_{cr,susp} (m/s)")
grid minor on

Appendix C: Bed Velocity Analysis

The following analysis provides a comparison of seabed velocities as a result of shipping propwash for 3 sets of vessel characteristics. The first set of characteristics is that of the vessel used in the BMT (2019) modelling and the second and third set of characteristics are from typical shipping vessels that still satisfy the dimensional limits of the proposed wharf. Seabed velocities will be estimated for prop rotational frequencies equivalent to cruise speed, further, thrust coefficients will align with the scenario that the vessel is at rest, and is subjected to a sudden burst of thrust. Regardless, the comparison will reflect differences in magnitudes of these bed velocities between analysed vessels.

Nominal continuous rating is at 75% SMCR (MAN 2018) i.e. the design speed of the vessel, therefore operating engine power may be expressed as,


Thrust power can be expressed as a function of engine power assuming reduction by a total propulsive efficiency,


Substituting (1) into (2), an expression for net vessel power in terms of SMCR power results,


Vessel thrust can be expressed as a function of thrust power and vessel velocity,

Substituting (3) into (4), gives a function of SMCR power for thrust,

Thrust coefficient is expressed as follows (MIT 2006),


Substituting (5) into (6),


Advance ratio is given by (MIT 2006),


Using the plot of typical torque and thrust coefficients in Figure 1, an approximate linear function for thrust coefficient can be derived,

Figure 1: Typical thrust and torque coefficients (MIT 2004).

Substituting (7) and (8) into (9),


Equation (10) can be solved for n, the propeller frequency. The vessel modelled in the BMT hydrodynamic simulations has a SMCR power of and prop diameter of (2019). The total propulsive efficiency can be estimated at (Valentine 2012) and design velocity is assumed to be approximate to other vessels of similar size, (MAN 2013). Substituting in values and solving,



Efflux velocity is expressed as follows (Fuehrer and Römisch 1977, cited in Hamill et al. 2015),


Resultant maximal bed velocity from propwash can be estimated as (Fuehrer and Römisch 1987, cited in Stoschek et al. 2014),

Substituting (11) into (12) gives an equation from which we can use to calculate potential bed velocities at a given depth,


For maximum thrust coefficient, it is assumed the vessel is powered suddenly from rest to cruise, therefore, advance coefficient is  and  from figure 1, thrust coefficient is . It’s also assumed the vessel rudder is in central position, which results in (Stoschek et al. 2014). As an arbitrary depth, let’s use 15m; the same depth at the ecologically significant site 16 on the approach/departure trajectory. Using draft from the modelled vessel, vertical distance from prop axis to seabed may be calculated,


Substituting discussed values into (13), the maximum bed velocity results,


For comparative purposes, maximum bed velocity will now be calculated for a vessel possessing a higher SMCR, but still satisfying the dimensional limits of the wharf, as described in table 1. Propeller diameter is not provided, but can be estimated from vessel draught using an upper limit of diameter to draft ratio of 0.75 (MAN Energy Solutions, 2018). Considering the preference towards a higher efficiency and lower fuel consumption, a larger propeller diameter is generally chosen (MAN Energy Solutions, 2018). Therefore, it is reasonable to use the upper limit of the diameter to draft ratio for calculation of a diameter,


Using equation (10) and solving, we can now find propeller frequency for the new vessel. All parameters besides SMCR power, propeller diameter and speed are consistent,

Calculating vertical distance from prop axis to seabed,


Using equation (13) to calculate maximum bed velocity,


Interestingly, this value is higher than the calculated bed velocity for the vessel modelled in the BMT hydrodynamic analysis, indicating either that simulations will have underestimated sediment mobilization, or statements suggesting the wharf can be used for vessel up to 11.75 m is misleading.  

Table 1: Characteristics of a typical panamax vessel from MAN Diesel & Turbo (2013).

Container ship class

Panamax

Length between pp (m)

232

Ship size (TEU)

3500

Breadth (m)

32.2

Scantling draught (m)

12.7

Sea margin (%)

15

Deadweight (scantling) (dwt)

46700

Engine margin (%)

10

Design draught (m)

11.3

Average design ship speed (kts)

23.5

Deadweight (dwt)

38100

SMCR Power (kW)

31,300

Length overall (m)

246

Engine Options

6K90ME9/ME-C9

7K90MC-C6/ME-C6

7K80ME-C9

9K80MC-C6/ME-C6

It could be argued that the chosen prop diameter is too large, as such, maximum bed velocities have been calculated for varying prop diameters, and still, right down to 6m (below the prop diameter of the BMT modelled vessel) we still see higher maximum bed velocities.

Table 2: Resultant maximum bed velocity for varying prop diameters.

Prop Diameter (m)

n (Hz)

Maximum Bed Velocity (m/s)

8.48

1.72

11.12

8

1.87

11.10

7.5

2.05

11.05

7

2.26

10.98

6.5

2.53

10.98

6

2.85

10.93

A third and final analysis will be performed on a smaller panamax vessel still with SMCR power higher than that of the BMT modelled vessel. Characteristics of this vessel are described in Table 3.

Again using the prop diameter to draft ratio from MAN Energy Solutions (2018), we can find the upper limit prop diameter for this vessel,

Using equation (10) and solving, we can now find propeller frequency for the new vessel. All parameters besides SMCR power, propeller diameter and vessel velocity are consistent,

Calculating vertical distance from prop axis to seabed,


Using equation (13) to calculate maximum bed velocity,

Again, the calculated value of maximum seabed velocity is higher than that of the vessel used in modelling.

Table 3: Characteristics of a typical panamax vessel with 2800 TEU from MAN Diesel & Turbo (2013).

Container ship class

Panamax

Length between pp (m)

196

Ship size (TEU)

2800

Breadth (m)

32.2

Scantling draught (m)

12.0

Sea margin (%)

15

Deadweight (scantling) (dwt)

38,500

Engine margin (%)

10

Design draught (m)

10.7

Average design ship speed (kts)

22.5

Deadweight (design) (dwt)

30,800

SMCR Power (kW)

25,000

Length overall (m)

211

Engine Options

6K80ME-C9

7K80MC-C6/ME-C6

8L70MC-C8/ME-C8

8S70MC-C8/ME-C8

AusOcean Report No. 2019.3                                                                                


[1] For detailed surveying methodologies see Smith Bay Marine Ecology Report prepared by AusOcean https://www.ausocean.org/s/doc/2019_AusOcean_Smith_Bay_Marine_Ecology_Report.pdf.

[2] Cruise velocity for vessel from BMT analysis has been estimated to that of similarly sized vessels.