ROEBUCK BAY LYNGBYA MONITORING PROGRAM

SORA M. ESTRELLA

UNIVERSITY OF WESTERN AUSTRALIA

MAY 2013

Roebuck Bay Lyngbya Monitoring Program 2

Prepared by:

Sora M. Estrella, University of Western Australia within the project “Effects of nutrient enrichment and toxic Lyngbya blooms on benthic invertebrates-and migratory shorebird communities of Roebuck Bay Ramsar site” funded by NRM Office, NRM Rangelands, DEC Kimberley and Port of Broome.

This document has been prepared with all due diligence and care, based on the best available information at the time of publication. SME and UWA hold no responsibility for any errors or omissions within this document. Any decisions made by other parties based on this document are solely the responsibility of those parties.

May 2013

Roebuck Bay Lyngbya Monitoring Program 3

Table of contents

Executive summary 4 1. Introduction 5 2. Objectives 6 3. Monitoring area 6 4. Detection and monitoring of Lyngbya 6 4.1. Intertidal transects 7 4.2. Mapping of bloom extension 10 4.3. Aerial surveillance 11 4.4. Community monitoring 11 5. Lyngbya accumulation on beaches 11 6. Equipment and people required 12 7. Health and safety issues 12 References 14 Annexe 1. Reference table of pictures Annexe 2. Field data spread sheet

Roebuck Bay Lyngbya Monitoring Program 4

Executive summary

Since 2005 blooms of Lyngbya majuscula have been occurring in the intertidal zone of Roebuck Bay. A study funded by the NRM Office, DEC Kimberley and Port of Broome, carried out by researchers from The University of Western Australia indicated that major Lyngbya blooms have caused significant changes in the intertidal benthic community composition as well as changes in shorebird foraging behaviour in Roebuck Bay. To manage Lyngbya blooms in Roebuck Bay an appropriated monitoring program is needed to document frequency and extent of blooms. This Roebuck Bay Lyngbya Monitoring Program provides a rapid and practical approach to monitor blooms across Roebuck Bay. The actions outlined in this monitoring program are aimed at monitoring change in Lyngbya occurrence and biomass through the wet season in near-shore areas of Roebuck Bay.

The objectives of the monitoring program for Lyngbya in Roebuck Bay are to:

- Provide DEC and the local government with regular updates on presence and spatial extent of Lyngbya blooms in Roebuck Bay.

- Deliver DEC and the local government with regular updates on development of Lyngbya blooms through each wet season in Roebuck Bay.

- Offer regular communication on the status of blooms to the community via DEC and other stakeholders.

Roebuck Bay Lyngbya Monitoring Program 5

1. Introduction

Roebuck Bay is one of the main wintering and refuelling stop-over areas for migratory shorebirds of the East Asia-Australasia fly way. The importance of Roebuck Bay appears to relate to the incredibly high diversity and biomass of benthic invertebrates, which places this tropical intertidal area among the richest mudflats in the world (Piersma et al. 1998). Roebuck Bay was designated as a Wetland of International Importance in 1990 under the Ramsar Convention (1971), and it currently ranks in the top 8 shorebird migratory stop-over sites in the world (Rogers et al. 2003). Recognising its ecological richness, Roebuck Bay was proposed as a Marine Park in 2010. It is, therefore, a highly significant shorebird habitat, worthy of preservation at a national and international level. However, since 2005 blooms of Lyngbya majuscula have been occurring in the intertidal zone of Roebuck Bay.

Lyngbya majuscula is a natural occurring cyanobacteria of tropical and temperate coastal waters (Johnstone et al. 2010). However, human induced changes are known to lead to the exponential growth of this cyanobacterium, resulting in damaging blooms (Ahern et al. 2008). A recent study funded by the NRM Office, DEC Kimberley and Port of Broome, and carried out by researchers from The University of Western Australia indicated that major Lyngbya blooms have caused changes in the intertidal benthic community composition as well as changes in shorebird foraging behaviour in Roebuck Bay (Estrella et al. 2010, Estrella 2013). Also, studies carry out in Moreton Bay, Queensland, have found human health issues related with Lyngbya blooms, including breathing problems and skin reactions (Osborne et al. 2007). Therefore to manage Lyngbya blooms in Roebuck Bay an appropriated monitoring program is needed to detect changes in the occurrence and extent of Lyngby growth, and thereby allow relevant agencies to inform the public of potential health issues. The monitoring program should be included within the ongoing monitoring programs that the Department of Environment and Conservation already conduct across Roebuck Bay.

This Roebuck Bay Lyngbya Monitoring Program provides a rapid and practical approach to monitor Lyngbya blooms across Roebuck Bay. The actions outlined in this monitoring program are aimed at monitoring the change in occurrence of Lyngbya through the wet season in the near-shore areas of Roebuck Bay. The monitoring techniques have been developed from previous trials of techniques during the 2010-2011-2012 blooms in Roebuck Roebuck Bay Lyngbya Monitoring Program 6

Bay as part of the project “Effects of nutrient enrichment and toxic Lyngbya blooms on benthic invertebrates-and migratory shorebird communities of Roebuck Bay Ramsar site”. The monitoring plan has the flexibility to suit various bloom situations and focuses on areas in Roebuck Bay known to have had Lyngbya blooms in the past.

2. Objectives

The objectives of the program to monitor Lyngbya in Roebuck Bay are to:

- Provide DEC and the local government with regular updates on presence and extent of Lyngbya in Roebuck Bay.

- Deliver DEC and the local government with regular updates on development of Lyngbya blooms through the wet season in Roebuck Bay.

- Offer regular communication of the status of blooms to the community through DEC and other stakeholders.

3. Monitoring Area

This plan could be adapted to various bloom situations. However, it primarily focuses on the areas where blooms that adversely impact on the local environment have been observed in recent years, and may affect the public use of the coast. These areas are the north-western region of Roebuck Bay (Port of Broome to Town Beach) as well as the intertidal area of the northern beaches of the Bay (Dampier Creek to One Tree) (Figure 1).

4. Detection and monitoring of Lyngbya

Four approaches are recommended to detect and monitor the growth of Lyngbya. These include:

- Intertidal transects. Roebuck Bay Lyngbya Monitoring Program 7

- Maximum extension bloom mapping. - Aerial surveillance. - Community monitoring.

Since Roebuck Bay has a supratidal regime, with tides > 9 meters, all the monitoring activities should be conducted during low tide on the spring tides of each month. This provides greatest exposure of the mudflats, allowing optimum conditions for assessment of Lyngbya growth.

It is worthy to note that due to the elevated turbidity of the bay, with high concentrations of sediments in suspension, it is not possible to develop any program base on monitoring Lyngbya by visual assessment of its location and extent during high tide, as has been possible in other systems (i.e. Moreton Bat in Queensland).

4.1. Intertidal transects

This aspect of the program will provide detailed information on the development (i.e. coverage) and severity (i.e. biomass) of the bloom through the wet season.

From the previous study in Roebuck Bay (Estrella 2013) two hot spots of Lyngbya presence and density were identify. One was localised in the area between Port of Broome and Town Beach, an area known as Demco (see Figure 1 and Table 1). The other area was between Dampier Creek and Fall Point, approximately on the intertidal area of Camp Site beach (see figure 1 and table 1), in the northern beaches of the bay.

At both sites a transect perpendicular to the coast has been established. The position of the monitoring transects may be modified in order to match their location with areas affected by Lyngbya. Every 100 meters along the transect from the shoreline, three quadrats of 25 cm x 25 cm will be randomly placed within a 5 meters radius of the survey point. The Lyngbya presence within the quadrats will be compare with the reference table of pictures, and an average calculated from the three quadrats (Appendix I). The pictures in Appendix 1 provide a range of coverage and biomass of Lyngbya calculated during the project “Effects of nutrient enrichment and toxic Lyngbya blooms on benthic invertebrates and migratory Roebuck Bay Lyngbya Monitoring Program 8

shorebird communities of Roebuck Bay Ramsar site, 2013” (Table 2). The reference table of pictures is provided to allow field assessment of biomass, and so avoid manual handling of the Lyngbya, and also field and laboratory time.

Table 1: Coordinates of the monitoring transects for their approximately location.

Transect name GPS coordinates

DEMCO 17°58'52.20"S 122°13'12.70"E Camp Site 17°58'56.40"S 122°19'28.70"E

Table 2: Table indicating the relationship between Lyngbya density assessment and Lyngbya biomass.

g DM /m2 Density 0 No presence

<10 Very low 10-50 Low

50-150 Medium 150-300 High >300 Very high

It is important to note that the structure and morphology of mats of Lyngbya differ greatly with habitat, for example particularly in seagrass beds. While seagrass coverage could be clearly determine within a quadrat, Lyngbya mats are usually in the form of compacted beds of filaments. Therefore a careful assessment of each quadrat is required. Nevertheless, even with the potential biomass assessment error associated withvariability on the morphology of mats of Lyngbya, the information provided by monitoring these two transects will provide quantitative data on Lyngbya biomass and severity of blooms on these two transects. Roebuck Bay Lyngbya Monitoring Program 9

To record the collected data, two options are available. One is the direct assessment of Lyngbya biomass in the field and transcription of the data to the field data spread sheet (example in Appendix II). The alternative is to take a digital image of each quadrat and conduct the assessment of Lyngbya biomass in the office by comparing the images with the reference table of pictures (Appendix I). This second option allows subsequent re-analysis of the images, and will provide a permanent database of images for future reference.

Camp site transect

DEMCO transect

Figure 1: Map with the approximate location of the two transects to monitoring Lyngbya majuscula in Roebuck Bay, NW Australia.

The transect monitoring will be conducted monthly from December to April – or when Lyngbya is evident. It is recommended that the monitoring of both transects is carried out Roebuck Bay Lyngbya Monitoring Program 10

on the same day or on two consecutive days. This will allow future comparison of the data between both sites.

4.2. Mapping of bloom extension

This approach allows for the spatial mapping of Lyngbya blooms across the Bay. Although Lygnbya often occurs with a patchy distribution, it is possible to map the external limits of the bloom across the Bay.

Using a hovercraft at low tide, the area of the bloom may be determined by following the outer limits of the bloom, and marking waypoints along the perimeter of the bloom with a GPS. Using these waypoint it is possible to calculate the area occupied by the bloom, and display this on a map of the Bay using GIS; some GPS units have a function that will calculate the area within the waypoints. This mapping of the extent of Lyngbya should be done at least three times in the wet season/per bloom, or more frequently if a more detailed record of changes in area is required. Mapping should commence in December, or when Lyngbya patches first appear in the intertidal area of the bay. The second mapping would then occur at the maximum extent of the bloom. Based on the three year study “Effects of nutrient enrichment and toxic Lyngbya blooms on benthic invertebrates-and migratory shorebird communities of Roebuck Bay Ramsar site”, the maximum extent of the bloom in Roebuck bay appears to occur in February. However, different environmental and climatological conditions could modify this pattern. Finally, the third mapping should be carried out between mid to late March, when Lyngbya is usually in decline. It is recommended that digital images are collected during the mapping from different parts of the bay. The images will provide information about new areas of Lyngbya occurrence and bloom severity.

This information will be critical to determine if the bloom has reached that part of the Bay listed under the Ramsar Convention. Also it will provided year to year information about changes in extent and distribution of Lyngbya.

Roebuck Bay Lyngbya Monitoring Program 11

4.3. Aerial surveillance

The intertidal area of the south part of the bay is very remote and only accessible by boat. It consists of sand flats and mud flats (Pipping et al. 1999). Lyngbya is prone to growth in sandy areas, and attached to rocks, shells and seagrass (Ahern et al. 2008). The only way to evaluate Lyngbya presence in the more distant southern parts of the bay is to conduct aerial surveillance of the whole bay. This surveillance should be done when the bloom is at its maximum extension, which the flight conducted at low tide on spring tides. When possible, a clear day should be selected to have a clear vision of the substratum. The members of the team should be seated on each side of the aircraft with access to windows. Pictures should be taken to evaluate Lyngbya presence. Recognisable geographical marks (e.g. creeks) may be used as location references, and GPS waypoints may be taken to mark occurrences and extent of any growth.

The information gathered in the surveillance will provided information about new locations of Lyngbya as well as modifications in the extension of the bloom.

4.4. Community monitoring

A system should be established whereby the general public, users of Roebuck Bay such as fishermen and environmental/ research groups and any other stakeholder can report the presence of Lyngbya by contacting the DEC. The Seagrass-Watch Monitoring Program, based on volunteers, is an excellent way to report the presence and changes of Lyngbya in Roebuck Bay.

5. Lyngbya accumulation on beaches

The accumulation of Lyngbya on beaches is a public health risks. Although within the Lyngbya Contingency Plan of Roebuck Bay, it is important to monitor the presence and accumulation of Lyngbya on beaches of Roebuck Bay during the wet season and report its presence to DEC. Roebuck Bay Lyngbya Monitoring Program 12

6. Equipment and people required

The following personnel and material will be required to carry out the proposed monitoring program

- Intertidal transects: If both transects are going to be surveyed on the same day, then two people per transect will be required. If the transects are going to be monitored in two consecutive days, then same team of two people can carry out the assessment. One person would use the GPS to locate the transect and each station at 100 m intervals, as well as transcribe the information to the field data sheet. The other member of the team would set the quadrats and assess Lyngbya biomass and/or take pictures of the quadrats. The required material is: one GPS per team, one quadrat of 25 x 25 cm per team, a digital camera, batteries for the GPS and the camera, pencil (x2) and one waterproof note book. - Mapping maximum extension of the bloom: One team of two people would be required. One person will be the hovercraft skipper and pilot. The other person would use the GPS to mark the waypoints and take pictures. The required material is: one GPS, a digital camera, batteries for the GPS and the camera, pencil (x2) and one waterproof note book. All the health and safety material required for using a hovercraft should be provided by the hovercraft owner. - Aerial surveillance: One team of at least two people would be required. Both members should take pictures. The required material is: two digital cameras, batteries for the cameras, pens (x4), GPS to mark the waypoints and two note books. All the health and safety material required when using an aircraft should be provided by the aircraft owner.

7. Health and safety issues

Lyngbya may be toxic and produce breathing problems as well as skin reactions (Osborne 2007). The monitoring program here presented has intentionally avoided recommending handling of Lyngbya. However, any Lyngbya contact should be avoid and gloves and reef walkers or waders should be use when doing the intertidal transects and the Lyngbya Roebuck Bay Lyngbya Monitoring Program 13

mapping. If any breathing problems and/or skin reactions are detected, it is recommended to stop the monitoring and seek medical advice. DEC should be informed of these events.

Roebuck Bay Lyngbya Monitoring Program 14

REFERENCES

- Ahern, K.S., Ahern, C.R., Udy, J.W. 2008. In situ field experiment shows Lyngbya (cynaobacterium) growth stimulated by added iron, phosphorus and nitrogen. Harmful Algae 7:3 89-404. - Estrella, S.M., Storey, A.W., Pearson, G. and Piersma, T. 2011. Potential effects of Lyngbya majuscula blooms on benthic invertebrate diversity and shorebird foraging ecology at Roebuck Bay, Western Australia: preliminary results. Journal of the Royal Society of Western Australia 94: 171-179. - Estrella, S.M. 2013. Effects of nutrient enrichment and toxic Lyngbya blooms on benthic invertebrates-and migratory shorebird communities of Roebuck Bay Ramsar site. Scientific Report. - Johnstone S., Fielding F., Hamilton G. and Mengersen K. 2010. An Integrated Bayesian Network approach to Lyngbya majuscula bloom initiation. Marine Environmental Research 69: 27-37. - Osborne, N.J., Shaw, G.R., Webb, P.M. 2007. Health effects of recreational exposure to Moreton Bay, Australia waters during a Lyngbya bloom. Environment International 33: 309-314. - Pepping, M., Piersma, T., Pearson, G.B., Lavaleye, M. (eds). 1999. Intertidal sediments and benthic animals of Roebuck Bay, Western Australia., NIOZ-report 1999-3, Texel. - Piersma T., Pearson G.B. and Lavaleye M. 1998. The teeming mud of Roebuck Bay. Landscope 13: 16-22. - Rogers D., Piersma T., Lavaleye M., Pearson G. B. and de Goeij P. 2003. Life along land’s edge. Department of Conservation and Land Management. Appendix I

Date / / Transect: Team members:

Low tide hour: Page: Climatology:

Station Replicate Lyngbya density Picture Notes: 0 A 0 B 0 C 100 A 100 B 100 C 200 A 200 B 200 C 300 A 300 B 300 C 400 A 400 B 400 C 500 A 500 B 500 C 600 A 600 B 600 C 700 A 700 B 700 C

Appendix II < 10 g Lyngbya DM / m2

10 -50 g Lyngbya DM / m2

50- 150 g Lyngbya DM / m2

150 - 300 g Lyngbya DM / m2

*

* *

*NOTE: Lyngbya could be concentrate in holes in the sediment or cover by sand.

> 300 g Lyngbya DM / m2