BENTHIC ECOLOGY, COASTLINE & TURBIDITY BASELINE REPORT

BENTHIC ECOLOGY, COASTLINE & TURBIDITY BASELINE REPORT Prepared for Te Atinimarawa Co Ltd Channel Dredging Project t-m’akei services Tarawa Kiribati July 2013 Client, Consultant and Reviewers Client Client Environmentally Safe Aggregates for Tarawa Project, Ministry of Fisheries and Marine Resources Development Office Bairiki, Tarawa Phone/Fax (686) 21099, (686) 21120 Contact P O Box 64 Consultant Company t-makei Services Office Teaoraereke, Tarawa Phone/Fax (686) 29803 Email [email protected] Document track and status Revision Prepared by Reviewed by Draft 1 Riibeta Abeta and Date Revision Details Dr Temakei Tebano 20.07.2013 - Karibanang Aram Nicholas Harding 31.07.2013 Internal Review Riibeta Abeta and Dr Temakei Tebano Karibanang Aram Nicholas Harding 05.08.2013 – 21.08.2013 FINAL DRAFT Riibeta Abeta and Tekiete Tutu Karibanang Aram Nicholas Harding Revised final draft Riibeta Abeta and Dr. Temakei Tebano Draft 2 Karibanang Aram 2 Approved by ECD MELAD Internal Review Internal Review Internal Review Table of Contents 1.0 BACKGROUND ............................................................................................................ 8 2.0 PURPOSE OF ACTIVITY ............................................................................................. 9 3.0 DESCRIPTION OF METHODS AND SAMPLING SITES ......................................... 9 3.1 Marine Ecological Assessment ................................................................................... 9 3.2 Coastline profiling ..................................................................................................... 12 3.3 Turbidity .................................................................................................................... 15 4.0 FINDINGS – Baseline conditions ................................................................................ 17 4.1 Marine ecological assessment (benthic) .................................................................... 17 4.2 Coastline .................................................................................................................... 24 4.3 Turbidity .................................................................................................................... 31 5.0 ANALYSIS OF FINDINGS (Baseline conditions) ...................................................... 33 5.1 Marine ecological assessment (benthic) .................................................................... 33 5.2 Coastline .................................................................................................................... 34 5.3 Turbidity .................................................................................................................... 35 References ................................................................................................................................ 38 3 List of Tables and figures Table 1. Table showing GPS locations of marine ecological study stations and their descriptions ..... 10 Table 2. Table showing GPS locations of beach profiling stations and their descriptions ................... 13 Table 3. GPS Coordinates of water turbidity sampling points.............................................................. 15 Table 4. Findings of Beach profiling for each stations/Sites ................................................................ 25 Table 5. Regression trends for each beach profile station. ................................................................... 30 Figure 1. Map showing Site proposed for channel ................................................................................. 8 Figure 2. Map showing position and distribution of ecological study transect line .............................. 11 Figure 3. Levelling equipment and reading staff used in the coastal monitoring exercise ................... 12 Figure 4. Map showing distribution of beach monitoring stations ....................................................... 14 Figure 5. Distribution of sampling points for water turbidity ............................................................... 16 Figure 6. Percentage substrate type for the three study Sites ................................................................ 18 Figure 7. Type of benthic cover found on each study Sites .................................................................. 19 Figure 8 (a) & (b). Group of organisms found on a) surface b) below the surface for Site 1 ............... 20 Figure 9 (a) & (b). Group of marine organisms found a) on the surface b) below the surface for Site 2 .............................................................................................................................................................. 21 Figure 10 (a) & (b). Group of marine organisms found on a) on the surface b) below the surface for Site 3 ..................................................................................................................................................... 21 Figure 11. Density of important group of organisms found during the study. ...................................... 22 Figure 12. Total number of marine organisms found on different substrate for the 3 Sites ................. 23 Figure 13. Dry weight readings for shallow and deep water sampling points during Neap tide .......... 31 Figure 14. Dry weight readings for shallow and deep water sampling points taken during Spring tide .............................................................................................................................................................. 31 Figure 15. NTU readings for shallow and deep water sampling points taken during Neap tide .......... 32 Figure 16. NTU readings for shallow and deep water points near ESAT lagoon taken during Spring tide ........................................................................................................................................................ 32 4 EXECUTIVE SUMMARY This Environmental Impact Assessment report presents the results of a baseline study of the marine ecology, coastline monitoring and lagoonal seawater turbidity levels in relation to the proposed channel for ESAT Project at Takoronga lagoon, Betio, South Tarawa closer to the Betio end of Nippon causeway. The study was undertaken in accordance with the conditions of the Environmental License of this ESAT boat channel project that has been approved by the Government of Kiribati through its Environment and Conservation Division of the Ministry of Environment Lands and Agricultural Development (MELAD) as the implementing arm of the Kiribati Environment Act 1999. The ESAT project is a European Union funded project for the Government of Kiribati, executed by SOPAC on behalf of the Ministry of Fisheries and Marine Resources Development (MFMRD) through Mineral Division. The project is part of the Government of Kiribati efforts in mitigating substantial aggregate mining on the coastline and limited land of South Tarawa, aiming to meet the demand for local aggregate materials required for infrastructure and physical development through supplying affordable and locally sourced aggregates. An additional benefit is that it will increase the building of national resilience to counteract the impacts of climate change and sea level rise that could be exacerbated by severe mining and coastal erosion. The main objective of the Project is to establish a new Government’s Aggregates Mining Company, Te Atinimarawa Company Limited (TACL) that will develop and market alternative source of aggregates that is environmentally safe, adequate and affordable for local supply demands for physical and infrastructure development; at the same time to provide the mechanism for reducing and eventual cessation of beach mining activities. Offshore Sites within the lagoon of Tarawa have been identified and assessed for the dredging of aggregate by the company. However, in order for the aggregate to be transported smoothly from its points of extraction to shore depots, it requires easy access of the dredging barge to its Sites in Takoronga at the old OECC and PWD yards now owned by the company. 5 This triggers an initial EIA study to gather baseline information on parameters required under the conditions of an Environment license to be carried out in the boat channel vicinity before and after the dredging commences. To date, due to unforeseen circumstances, the excavation of A1 area for the channel was put on hold. Mac Connell-Mac Dow, the road construction contractor, is excavating A2 area next to the existing burrow that would be connected with the proposed channel. This marine ecological assessment show that the dominant marine organisms identified in the area includes, Anadara (te bun), corals, lollyfish (nautonga), Gafrarium (koumara) and Strombus (nouo). However their quantity and density over the total assessed area is insignificant in terms of much needed marine resource on a daily basis. The coastline monitoring found active sediment movement from east to west and a clear and rife erosion pattern evidenced in most of the assessed monitoring stations. Causes cannot be determined but assumptions based on physical observation on sand mining along the causeway, aggregate mining was also witnessed at the immediate lagoon side of the study area. The turbidity levels for the studied area reflect a relatively clear and normal condition which is far below world acceptable levels, vary slightly during different lunar seasons. The study concurs with Environmental License (EL) conditions on the need to undertake monitoring during and after the commencement of the dredging to investigate further indepth the role of different parameters including dredging activities of this project and other related activities on marine ecology, coastline movement and turbidity levels. This study recommends the following, in light of the scope and context of the dredging development for EL monitoring obligations (paragraph 40 – 43):   Future monitoring (for coastline, ecology and turbidity) applies the same methods engaged in this study; For coastline future monitoring, consider adding 1-2 stations/points near residential coastal structures within the 500m west of the excavated area coverage; 6  Monthly monitoring (as per paragraph 41 of EL condition) for coastline and turbidity may wish to take note of different lunar phases of the moon e.g. during full moon and neap tide periods. Acronyms and Abbreviations ESAT EIA EL ENSO GPS NTU SOE Environmentally Safe Aggregates for Tarawa Environmental Impact Assessment Environmental License El Nino and Southern Oscillation Global Positioning System Nephelometric Turbidity Unit State Owned Enterprise 7 1.0 BACKGROUND The baseline study examined ecological marine fauna, turbidity levels and coastline profiles, was conducted from 5 - 18 May, 2013. The proposed channel is a necessity for the Government’s State Owned Enterprise (SOE), Te Atinimarawa Co Ltd, to provide easy access for the dredging barge that will transport aggregates from offshore dredging Sites at Betio, to the company’s processing yard at Takoronga, Betio (Lovell 2012). This is a Government project aimed to provide local supplies of aggregates for Tarawa. The proposed channel area connecting the deep water lagoon to the existing burrow pit near the shoreline at the company’s compound is exposed during low tide and relatively shallow during high tide making access to the stock piling depot difficult (refer to figure 1), hence there is a need to dredge this area referred to as A1. Part of the proposed Site, closer to the shoreline already had a few burrow pits that were dug out by OECC Company during the Betio road and causeway constructions. The depth of these burrow pits is around 3 meters during high tides and covers an extensive area of around 200m2 littoral mudflat zone. Proposed site for channel to be excavated Figure 1. Map showing Site proposed for channel 8 The Environmental License is a legal requirement under the Environment Act 1999 (as amended in 2007 section 14). Given the significant quantity suggested to be excavated from lagoon reef-mudflat for the channel, a baseline EIA study was triggered. The main areas of interest, as stipulated in the EL (MELAD 2011), for the baseline study, include; i. Marine ecology (benthic) ii. Turbidity levels and iii. Coastline change (profiles) 2.0 PURPOSE OF ACTIVITY The primary objective of this report is to comply with the EL monitoring conditions (paragraph 40 and 43(b) of Te Atinimarawa Company Limited channel excavation development, where it relates to undertaking and reporting baseline data on i) marine ecology ii) coastline profile and iii) turbidity level. The final objective of the study is to assist the Company in establishing stations/Sites and methods for their future monitoring obligations, also in accordance to paragraph 41 and 43(d) and (e) of the same EL conditions (MELAD 2011). 3.0 DESCRIPTION OF METHODS AND SAMPLING SITES This section describes methods and sampling Sites engaged for each of the 3 different assessments. The reasons for choosing sampling Sites is also clearly outlined in each study focus – Marine ecology, Coastline and Turbidity. 3.1 Marine Ecological Assessment The proposed area for the channel was observed to be quite isolated from local community residences – as hardly any gleaning events spotted through-out the time of the study. Equipments and Method The method employed in this study is the common point intercept transect (PIT) method (Abbot 1995) in which a transect line was laid on the intertidal flat starting from high tide water mark, down the flat to the end of the low water mark or edge of the sea-grass zone. 9 Data was collected at every 10m interval using a 1m2 quadrate laid out at both sides of the transect (measuring tape). Data collected included sediment type, type of benthic cover found above and below sediment surface, organisms found above and below surface. A spade was used to dig up the sediment down to about 10cm, sieved through a 5mm metal mesh to get the organisms below the surface. Data was collected onto a slate, a Reef Organisms’ Field Guidebook was consulted for organism identification. Sampling Sites There are three (3) different transects which formed the basis of the assessment within the vicinity of the proposed boat channel. The transects were intended to determine a shoreline/lagoon-ward distribution pattern of organism across the mudflat within the confines of the area specified under the condition of the EL (which is 500m in radius from the centre of the proposed excavated boat channel refer to Table 1 and figure 2). Both quantitative and qualitative aspects of the ecological study were addressed. This is standard scientific method for assessing richness, diversity and abundance of any given area and therefore covered also the required 500m radius as per condition 40(b). Table 1. Table showing GPS locations of marine ecological study stations and their descriptions Ecological study Site GPS locations Description of surrounding environment 1 Start N 01° 20.966 E172° 56.892 Located west of the proposed channel Site about 50m from the edge of the concrete seawall. During low tide this Site is usually more elevated on both sides. End N 01°21.135 E 172°57.014 2 Start N 01° 20.905 E 172° 56.944 Located in the centre of the proposed channel and it is also the centre of one of the existing dug pit End N 01° 21.097 E 172° 52.086 3 Start N01020.846 E 172057.102 End N 01° 21.030 E 172° 57.162 Located about 500m east of the proposed channel opposite the Police post close to the course-way toll booth. 10 Site 1 Transect lines Site 2 Site 3 Figure 2. Map showing position and distribution of ecological study transect line 11 3.2 Coastline profiling Equipments and Method This assessment employed a common “stake and horizon – Emery method” concept normally applied for beach profiling activities (Howorth 1982b) (UNESCO 2010). The method involves taking beach height readings (beginning from a reference height point at a berm of each beach Site) for every 2 meter intervals along the beach zone towards the reef mud flat when the height becomes stable or consistent. Equipments included the i) dumpy levelling equipment with tripod, ii) measuring tape iii) stretchable reading staff maximum length is 10m, iv) GPS v) camera and vi) slates and pencils. Figure 3. Levelling equipment and reading staff used in the coastal monitoring exercise Sampling Sites The beach monitoring stations/Sites were chosen randomly to cover the specified coastline distance under EL (which is 500 west of, and 2000m east of proposed ESAT channel development Site) subjected for monitoring under the Environment License for this Dredging development. The Sites were also chosen based on the absence/presence of beach, some areas do not have beaches for some reason or other. 12 A total of nine (9) beach profiling monitoring Sites/stations were established (refer to Table 1 and figure 4) spanning along the lagoon side of the studied coastline. A detail description of each monitoring Site/station is provided in Table 1 below. The coastline appears to be very exposed to forces of swells and dynamic water movement and currents. There are also topographic features like the Dai Nippon Causeway, sand mining, Te Atinimarawa seawall (formerly OECC’s), illegal squatter’s seawalls, paved ramps including excavations made already (burrow pits) by previous yard occupiers (OECC) that are already visible in the surrounding coastal area. Table 2. Table showing GPS locations of beach profiling stations and their descriptions Beach Profile Site GPS locations Description of surrounding environment 1 N01020.55 E172057.726 Approximately 200-300m east of fisheries channel of Nippon Causeway. The Site has very limited beach and dominated by causeway structure. 2 N01020.388 E172057.643 Approximately 50 – 60m east of fisheries channel. The Site has some accredited beach. 3 N01020.429 E172057.545 About 300m west of fisheries channel. The Site also has limited beach and sediment was made of coarse gravels predominantly. 4 N01020.629 E172057.329 Approximately 100m east of main accredited land of Nippon causeway – betio side. There are signs of fast and severe erosion and the coastline is made up of boulders and gravels. 5 N01020.734 E172057.138 Situated oppoSite the Police post in the Taiwan Park area. There is extensive beach accretion – small grains white beach sand predominantly. 6 N01020.912 E172056.955 Around the middle of Atinimarawa seawall coastline. There is very limited beach area with medium grain sands and gravels 7 N01021.49 E172056.877 Approximately 60-100m west of Atinimarawa seawall. There is some beach area closer to squatters’ seawall. 8 N01021.405 E172056.645 Lagoon side of Tenimanraoi maneaba. Extensive beach – small white grain sands and exposed to small seawalls of squatters. 9 N01021.679 E172056.421 Approximately 40-50m west of Mormon Church seawall. There are lots of concrete seawalls, ramp and other small protective seawall of residents around the area. There is some beach area but the Sites clearly have undergone intensive erosion. 13 Site 6 Site 9 Site 5 Site 7 Site 8 Site 4 Site 3 Site 2 Site 1 Figure 4. Map showing distribution of beach monitoring stations 14 3.3 Turbidity Equipment and Method Equipments employed for the turbidity sampling included a boat, 1- liter water sampling bottles (thoroughly cleaned) and a GPS device to mark the coordinates of each sampling location. Two different analytical methods were used for the two replicates of water samples. The first analysis employed the NTU machine (turbidity machine). The second method is by weight/volume (g/l) where suspended particles with known volume of sea water were separated from seawater through a filter paper, dried at room temperature, and weighed using a sensitive electronic scale (Abbot 1995). For this study, results from both methods are compared and discussed. Sampling Sites The water samples collected for turbidity testing were taken from six (6) different Sites (see figure 5 and Table 2). The sampling Sites were designed in a manner that would ensure water turbidity level was captured at different depth strands of water column, i.e. shallow and deeper water levels. Two replicate samples were taken from each Site. The turbidity sampling was conducted two times from each of the same sampling points - one during Neap tide (19th May); the other during Spring tide (2nd June). This is intended to investigate water turbidity conditions during these distinct moon phases and the lunar tide seasons. . Table 3. GPS Coordinates of water turbidity sampling points Sampling points 1A 2A 3A 1B 2B 3B GPS Coordinates (location) N01020.958 E172057.112 N01020.981 E172056.996 N01021.085 E172056.862 N01021.229 E172057.127 N01021.355 E172057.097 N01021.366 E172056.989 15 1B 2B Deeper sampling points 3B 1A 2A 3A Shallow sampling points Figure 5. Distribution of sampling points for water turbidity 16 4.0 FINDINGS – Baseline conditions 4.1 Marine ecological assessment (benthic) 4.1.1 Substrate type From the three (3) Sites, a total area of 156 m2 was covered by the point transect method. (note that this is the total area for point transect and their quadrant which are representative of the entire mentioned area). Site 1 represents 47%, Site 2 - 26% and Site 3 - 27%. The substrate types were categorised into three main groups such as sand, mud/silt and rubbles. The sandy substrate represents an area where there is more than 50% sand even though rubbles and mud could be present. The muddy substrate represents an area with more than 50% mud/silt and the rubble sediment represents an area with more than 50% rubble cover. The predominant substrate types for the study Sites are sand and rubbles while mud/silt represents only a small area. Figure 6 below shows the overall percentage for each type of substrate found in the three Sites. The distribution of substrate type along the transect line for the three Sites shows that mud/silt substrate only occupies the upper part of the flat followed by either sand or rubble substrate which are the main substrate type seen for all the Sites. 17 Figure 6. Percentage substrate type for the three study Sites 4.1.2 Benthic cover There are three (3) main types of algae found in the study areas which are i) filamentous green algae, ii) brown algae and iii) Halimeda. Sponge however was also sighted but only at Site 3. Brown algae is the predominating species for the three Sites and represent more than 35% of the total area covered for the three Sites. Figure 7 shows the percentage cover of these three types of algae and sponge for the 3 Sites. The general distribution of algae shows that filamentous green algae occupies only the upper part of the mudflat closer to the end of the beach and usually associates itself with mud/silt substrate. The highest percentage cover for filamentous green algae is seen in Site 3 and represents about 5% of the area. Halimeda occupies both the sand and rubble substrate, however it can only be seen in areas which usually contain small pools of water or areas which are not fully exposed during low tides. Site 3 shows the highest percentage cover of Halimeda and represents 24% of the area. 18 Figure 7. Type of benthic cover found on each study Sites 4.1.3 Organisms Quantity and Distribution All three study Sites show similar trends in the types and quantities of organisms found on and below the sediment surface. Organisms found on the surface are generally lower compared to those found below the surface. Even though the quantitiy of whelk and hermit crabs are quite significant on the surface the general pattern for the rest of the ornanisms are relatively low in quantity for those found on the surface compared to those found below the surface. 19 Figure 8 (a) & (b). Group of organisms found on a) surface b) below the surface for Site 1 20 Figure 9 (a) & (b). Group of marine organisms found a) on the surface b) below the surface for Site 2 Figure 10 (a) & (b). Group of marine organisms found on a) on the surface b) below the surface for Site 3 Figures 8, 9 and 10 above show the group of organisms found on and below the surface for Sites 1,2 and 3, respectively. Corals, Lollyfish (Holothuris atra), Anadara shell fish, Strombus and Gafrarium spp. are the only important and edible animals found that have environmental and economic values found on the study Sites. The density of these important species can be sighted in Figure 11. 21 Figure 11. Density of important group of organisms found during the study. The distributional pattern of organims along the mudflat, both above and below sediment surface, is not quite distinct except for whelk at the surface. This shows that whelk is higly associted with rubble substrate at the surface of the mudflat In addition, the study also shows that the quantity of organisms in the studied area seemed to be associated with substratum type, horizontally hierarched in quantity from most dry or harsh conditions i.e. rubble to watery substrate conditions i.e. mud. This trend is shown in Figure 12. 22 Figure 12. Total number of marine organisms found on different substrate for the 3 Sites 23 4.2 Coastline The results of the beach profiling for the nine (9) monitored Sites generally indicates that the majority of the coastline has undergone erosion. Site 1, 2 and 3 situated near the Nippon causeway channel clearly shows a very steep beach profile with a negative gradient or slope as well (as per Table 8). The surrounding area near Site 4 still shows remnants and strips of grasses (and some soils) cling to the upper edge of the Nippon Causeway. This is evidence of sediment or soil which was once at this ground level. Site 5 profile shows that it is accreting sediment. Also observed in the area near this Site is the abundance of scrubs and trees (especially burukam (Casuarina pine species)) which may also have some influence in retaining sediments. The profile for Site 6 reflects a reflective type of beach which may imply erosion. Immediately to the west, Site 7 and 8 shows accreted beach profiles. This could confirm the notion that sediment moves from east to west following the SE currents. The last monitoring station – Site 9 clearly shows an eroded beach profile. Near this station are huge coastal protective structures such as seawalls, etc. 24 Table 4. Findings of Beach profiling for each stations/Sites Site Visual shots of coastline and other topographic features Graphical Profiling 1 2 25 3 4 26 5 6 27 7 8 28 9 29 Table 5. Regression trends for each beach profile station. Beach Profile Site Beach slope (based on regression equation) Type and status of beach 1 Y = -8.409x - 28.54 Reflective 2 Y = -13.29x - 11.34 Reflective 3 Y = -8.763x - 23.6 Reflective 4 Y = -13.78x – 1.581 Reflective 5 Y = -16.89x + 44.52 Dissipative 6 Y = -13.43x – 18.01 Reflective 7 Y = -18.86x + 18.72 Dissipative 8 Y = -18.17x + 17.30 Dissipative 9 Y = -14.6 – 3.945 Intermediate (Reflective – implies very steep beach or beach with intense erosion; Dissipative – means less steep beach or accredited beach, Intermediate means in between reflective and dissipative) (Gourlay 1999) 30 4.3 Turbidity Figures 13 and 14 below present turbidity results (based on dry weight), while figure 15 & 16 are result readings of the NTU machine from sampling points. Figure 13. Dry weight readings for shallow and deep water sampling points during Neap tide Figure 14. Dry weight readings for shallow and deep water sampling points taken during Spring tide 31 Nephelometric Turbidity Unit (NTU) readings for sampling points. Figure 15. NTU readings for shallow and deep water sampling points taken during Neap tide Figure 16. NTU readings for shallow and deep water points near ESAT lagoon taken during Spring tide 32 5.0 ANALYSIS OF FINDINGS (Baseline conditions) 5.1 Marine ecological assessment (benthic) 5.1.1 Substrate type The current distribution pattern of sediment/substrate types shows that mud/silt substrate occupies the upper part of the flat usually just below the lower edge of the beach. The lower part of the flat toward sea-grass zone can be either sand or rubble substrate. 5.1.2 Benthic cover The study shows that filamentous green algae are mostly found in the upper part of the flat immediate to lower edge of beach zone and mostly found in mud/silt substrate. These types of algae are usually found in high nutrient waters suggesting that the areas closer to the beach are much higher in nutrient in comparison to sites further down the flats away from the beach margin. Underground water from land carrying high nutrient water might be one possible source of pollution. Site 3 shows the highest filamentous algae cover compares to the other two sites and the high human activity in the causeway area might be responsible for high nutrient at the site. The brown algae can be seen dominating the areas along the flats and mainly occupies the sandy and rubble substrates. Being the predominant species indicates that this algae species can tolerate extreme heat and dry conditions (Yeeting 2012). Halimeda on the other hand only occupies areas which have water pools indicating that Halimeda had a low tolerance to drying out. Site 3 is the only Site dominated by Halimeda and this is because the site has a large area with burrow pits and water pools holding water during low tides. The presence of few live corals at Site 3 shows that the area does not dry out during low tide. 5.1.2 Benthic Fauna and Flora) The distribution pattern and quantities of organisms on the surface shows that rubble substrate holds the highest number of groups and quantities of organisms followed by sand substrate. The mud/silt substrate does not hold any organism at the surface apart from filamentous algae. Organisms found below the surface also show a similar pattern however the quantities are generally higher than those found at the surface. The presence of mostly 33 juvenile organisms below the surface suggests that the flat provides a nursery area for these animals. Marine organisms prefer to live in substrate with a wide range of substrate compositions which coral-rubble substrate provides the highest complex habitat range followed by sand substrates. Mud/silt provides the least complex habitat and therefore had the least number of groups and quantity of organisms. The study shows that the density of important shellfish such as Anadara, Stromus and Gafrarium are 0.019/m2, 0.064m/m2, and 0.218/m2, respectively. It also shows a significant drop in Anadara density compared to 4 individual/m 2 in 1995 (as reference year) in approximately same study area, report compiled by Robert R Abbot (Abbot 1995) conducted as part of the Tarawa Lagoon Management Project. The heavy fishing pressure along the flat by residence around Betio and Bairiki could contribute to this high drop in density of these important shellfish (Yeeting 2012). However the findings of this study now sets a new baseline information (reference year as 2013) that could be used for reference in future studies. 5.2 Coastline From the above results (refer to Table 4 and 5), it is evident that a large extent of the coastline has already undergone major erosion processes, while few spots (Site 5, 7 & 8) are in the process of accretion. The important trend shown by results analysis is the eastward movement of sediments as most of the sites from 1 to 4 demonstrated a reflective beach form (implying less deposits of sediments) while Sites 5, 7 & 8 are dissipative (more flattened and accredited sediments). Parameters that determine the shape of the beach/coast of any particular site or region are combination of the works or functions of wave action, tide patterns, sediment types, and embayment variables including topographic infrastructures (Biribo 2008) (SOPAC 2005). 34 However, beaches/coastline can and do change dramatically both in space and time (Nicholls 2007). These changes are due to spatial and temporal contribution, of the important parameters mentioned earlier such as wave, tide, sediment, slope and topographic features that exist in the area. The need to understand the roles of such parameters both spatially and temporally is critical to predicting and understanding the impacts of other developments such as dredging, seawalls on the coastal area including beach mining activities (e.g. active beach mining near fisheries channel – Site 1 and 2). Assuming that wave and tidal patterns are variables that can be determined spatially, the role of existing coastal infrastructures along this shoreline on the dynamic movements of beach sediment is critical to be well understood. Therefore this assessment identified the eastward movement of sediment during this time of the year, which have resulted in erosion of some particular areas. Therefore it is critical that monitoring is conducted at different time spaces of the year e.g. during lunar phases of moon or particular seasons of ENSO. In addition, more in-depth monitoring and long term assessment would be required around the vicinity of existing coastal infrastructures to fully understand their roles over coastal beaches/sediments. Beach monitoring should also consider phases of dredging activities in order to determine accurately the role and impacts of dredging on coastline (which may affect wave/tidal waves strengths, patterns hence change coastline). 5.3 Turbidity There is a clear trend in Figure 13 and 14 which indicate that shallow water sampling points have more suspended particles compared to deeper water environment. The NTU readings also reflect same pattern. In the context of turbidity in the study area, this assessment attests that turbidity is higher in shallow water environment than deeper water environment. 35 The above trend accurately captured the nature of a working coastal environment whereby more water mixing and sediment/particles transport happened near the shoreline. The residual time for suspended particles to settle in the water column is slower in the shallow water environment compared to the deeper water environment. Tide patterns also prove to have influence on the turbidity level of water column. This trend is clearly depicted when comparing graphs in Figures 13, 14, 15 and 16. Suspended materials during Spring tide are much higher than in Neap tide periods. The normal standard for suspended particles (expressed by weight) by other countries vary but tends to be much higher (could range from 1.1 – 22 g/l) than readings in our results which are relatively lower (from 0.17 – 0.29 NTU). Information on environmentally safe standards for turbidity on lagoonal waters of atolls is very limited. This is partly due to different geographical circumstances of other countries. The maximum acceptable turbidity level for normal aquatic or marine life according to the Canadian/Australian Drinking/British Water Quality Guideline should not exceed the range of between 2.0 – 8.0 NTU (British 2012). It appears we do not have turbidity problem here in Tarawa lagoon but aggregate mining will determine the times and levels at which the dredging can operate in the months to come. This exercise therefore confirms that level of turbidity in the study Site falls below the lowest range for acceptable level in other countries. However, turbidity tends to increase during Spring tide periods, slightly lower in shallower water environments than to deeper water environment. 6.0 CONCLUDING STATEMENT This baseline study, for each study focus, concludes the following:  The marine ecological assessment identified only 3 groups of organisms in the area with relative low density. The species includes Anadara, Corals, Gafrarium, Holothuria, and Strombus. 36  The baseline coastline study re-affirms that coastline sediments are dynamic (change often) and tend to move from east to west during the time of the study. The assessment also concludes a clear and common erosion pattern already evident in most of the assessed monitoring stations.  The turbidity levels for the studied area reflect a relatively clear and normal condition but also varies slightly during different lunar seasons. The above provided the baseline basis for the fulfilment of the relevant conditions of the Te Atinimarawa Company Limited’s obligations under its Environmental License. 37 References Abbot, R. R. e. a., Ed. (1995). Tarawa Lagoon Management Plan. California, Biosystems Analysis Incorporated. Biribo, N. (2008). Analyses of spatial and multi-temporal coastal changes of selected Sites in Tarawa, Kiribati. Department of Marine Science. Suva, University of the South Pacific. Master of Science: 239. British (2012). "Turbidity." from http://www.env.gov.bc.ca/wat/wq/BCguidelines/turbidity/turbidity.html. Gourlay, M. R. S. a. M. R. (1999). "On the modelling of wave breaking and set-up on coral reefs." Coastal Engineering: 27. Howorth, R. (1982b). Coastal erosion in Kiribati. CCOP/SOPAC Technical report 22, SOPAC. Lovell, E. (2012). Environmental Impact Assessment Report for the ESAT Dredging Project. Fiji, Biological Consultants: 144. MELAD, E. (2011). Te Atinimarawa Environmental License for Excavation of Channel. Tarawa, ECD MELAD. Nicholls, R. J., P.P. Wong, V.R. Burkett, J.O. Codignotto, J.E. Hay, R.F. McLean, S. Ragoonaden and C.D. Woodroffe (2007). Coastal systems and low-lying areas. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. O. F. C. M.L. Parry, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds. UK, University Cambridge Press, Cambridge: 43. SOPAC (2005). An assessment of coastal processes, impacts, erosion mitigation options and beach mining EU EDF - SOPAC Project Report 46 Suva, SOPAC: 47. UNESCO (2010). Sandwatch. Adapting to climate change and educating for sustainable development. Paris, UNESCO: 136. Yeeting, B. (2012). EIA report of the ESAT: Impact on the Fisheries Resources. Tarawa, SPC: 55. 38 Annex 1. Attachments: Field raw results for turbidity readings Sample/Date 19/05/13 Neap tide 1A 1B 2A 2B 3A 3B Reading (NTU) 0.67 0.97 2.35 1.29 3.66 0.95 25/05/13 Spring tide 1A 1B 2A 2B 3A 3B Reading (NTU) 0.66 0.72 0.55 0.67 0.88 0.35 Weight Sediment 0.18 0.16 0.2 0.19 0.2 0.26 Weight Sediment 0.29 0.23 0.17 0.2 0.18 0.2 39