I hereby give notice that an ordinary meeting of the Great Barrier Environment Committee will be held on:




Meeting Room:



Wednesday, 26 March 2014


Claris Conference Centre
19 Whangaparapara Road
Great Barrier Island


Great Barrier Environment Committee









Susan Daly


Deputy Chairperson

Judy Gilbert



Jeff Cleave



Izzy Fordham



Christina Spence









(Quorum 3 members)




Guia Nonoy

Democracy and Engagement Advisor


18 March 2014


Contact Telephone: (09) 373 6218

Email: Guia.Nonoy @AucklandCouncil.govt.nz

Website: www.aucklandcouncil.govt.nz






Great Barrier Environment Committee

26 March 2014



ITEM   TABLE OF CONTENTS                                                                                        PAGE

1          Welcome                                                                                                                         5

2          Apologies                                                                                                                        5

3          Declaration of Interest                                                                                                   5

4          Confirmation of Minutes                                                                                               5

5          Leave of Absence                                                                                                          5

6          Acknowledgements                                                                                                       5

7          Petitions                                                                                                                          5

8          Deputations                                                                                                                    5

9          Public Forum                                                                                                                  5

10        Extraordinary Business                                                                                                5

11        Notices of Motion                                                                                                          6

12        Infrastructure and Environmental Services Update Report                                     7

13        Microdictyon and freshwater report                                                                           9

14        Community group and agency reports                                                                     27  

15        Consideration of Extraordinary Items 



1          Welcome


Chairperson Daly will welcome everyone in attendance. Member Cleave will lead a karakia.


2          Apologies


At the close of the agenda no apologies had been received.


3          Declaration of Interest


Members are reminded of the need to be vigilant to stand aside from decision making when a conflict arises between their role as a member and any private or other external interest they might have.


4          Confirmation of Minutes


That the Great Barrier Environment Committee:

a)         confirm the ordinary minutes of its meeting, held on Thursday, 27 February 2014, as a true and correct record.



5          Leave of Absence


At the close of the agenda no requests for leave of absence had been received.


6          Acknowledgements


At the close of the agenda no requests for acknowledgements had been received.


7          Petitions


At the close of the agenda no requests to present petitions had been received.


8          Deputations


At the close of the agenda no requests for deputations had been received.


9          Public Forum


A period of time (approximately 30 minutes) is set aside for members of the public to address the meeting on matters within its delegated authority. A maximum of 3 minutes per item is allowed, following which there may be questions from members.


At the close of the agenda no requests for public forum had been received.


10        Extraordinary Business


Section 46A(7) of the Local Government Official Information and Meetings Act 1987 (as amended) states:


“An item that is not on the agenda for a meeting may be dealt with at that meeting if-


(a)        The local authority by resolution so decides; and


(b)        The presiding member explains at the meeting, at a time when it is open to the public,-


(i)         The reason why the item is not on the agenda; and


(ii)        The reason why the discussion of the item cannot be delayed until a subsequent meeting.”


Section 46A(7A) of the Local Government Official Information and Meetings Act 1987 (as amended) states:


“Where an item is not on the agenda for a meeting,-


(a)        That item may be discussed at that meeting if-


(i)         That item is a minor matter relating to the general business of the local authority; and


(ii)        the presiding member explains at the beginning of the meeting, at a time when it is open to the public, that the item will be discussed at the meeting; but


(b)        no resolution, decision or recommendation may be made in respect of that item except to refer that item to a subsequent meeting of the local authority for further discussion.”


11        Notices of Motion


At the close of the agenda no requests for notices of motion had been received.


Great Barrier Environment Committee

26 March 2014



Infrastructure and Environmental Services Update Report


File No.: CP2014/04958




This report was not available at the time the agenda was sent to print and will be distributed separately.

Great Barrier Environment Committee

26 March 2014



Microdictyon and freshwater report


File No.: CP2014/04893





1.       This report describes the progress on the Microdictyon research program in Tryphena harbour and outlines the findings and recommendations for consideration by the Great Barrier Island Local Board and Environment Committee.

Executive Summary

2.       Sarah Roth (University of Auckland, Masters student) is nearing the end of her Masters program and is due to complete her thesis in April 2014. Sarah has completed her sampling to determine potential agents facilitating Microdictyon growth. These findings represent her research efforts and considerable thanks is forwarded to Sarah.

3.       This research program was designed to determine whether elevated nutrients were contributing to the presence of a green algae (Microdictyon umbillicatum) washing up on the beaches of Tryphena Harbour. This research program was equally funded by the Great Barrier Local Board and Auckland Council's Research, Investigations and Monitoring Unit (RIMU). Supervision of this research program was contributed to by the University of Auckland (Dr Nick Shears) and RIMU (Dr Jarrod Walker).

4.       In order to understand the relationship between Microdictyon blooms and nutrient levels at Tryphena Harbour, and in particular whether the blooms are associated with nutrient enrichment in the harbour, a program of water and seaweed sampling was carried out from October 2012 to February 2014.  Measurements of seawater nutrients (nitrogen and phosphorus) provided a direct measure of the nutrients available for seaweed growth and an overall measure of nutrient enrichment. Chemical analysis of seaweed tissue provides a measure of the overall nutrient status of the plant (as indicated by the percentage nitrogen in the tissue) as well as the main sources of Nitrogen (from stable isotope analysis). In addition, growth experiments were carried out to compare growth rates between Tryphena and adjacent Great Barrier Is sites.

5.       Extensive video tows in Tryphena Harbour and some surrounding bays revealed widespread beds of the green alga Microdictyon umbillicatum within Tryphena and limited amounts of Microdictyon in Okupu Bay on one occasion. The beds in Tryphena were found drifting or loosely attached to the sandy bottom at depths of 6 - 20 m.  These drifts persisted year round over the course of this study (October 2012 to Feb 2014). The amount of Microdictyon varied from one season to the next and from year to year. The greatest quantities of Microdictyon were observed between October 2012 and March 2013, but have been less extensive over the past year.

6.       Seawater nutrient monitoring did not reveal elevated nutrients within Tryphena Harbour compared to offshore waters and adjacent coastal sites. In general, total inorganic nitrogen and phosphate levels were typical of open coast sites with limited terrestrial inputs, and are comparable to seawater nutrient concentrations at Leigh on the mainland. Nutrient levels in Tryphena harbor are considerable lower than urbanised areas around Auckland (e.g. Waitemata Harbour).

7.       Isotope analysis of Microdictyon tissue from Tryphena Harbour revealed considerable variation over time. Tissue-δ15N values were within the expected ‘natural’ range on most sampling occasions, but elevated δ15N levels were recorded in spring 2012 and spring 2013. This provides some indication of periodic inputs of nitrogen from an anthropogenic source within the harbour.


8.       Growth experiments carried out in summer and spring 2013, provided no evidence that the growth of Microdictyon was higher in Tryphena compared to adjacent harbours, nor was there any differences in nutrient concentrations or tissue-δ15N values between sites in the Harbour and on the adjacent coast at that time. Sites to the south of Tryphena tended to have the highest growth rates, seawater nitrogen concentrations and percentage tissue nitrogen in Microdictyon than of those found at Tryphena.

9.       The unique physical setting of Tryphena Harbour likely facilitates the presence of Microdictyon.  The harbour is protected from large ocean swells, is dominated by coarse sand and shell hash, which provides substrate for Microdictyon attachment, and the clear oceanic water provides optimal growing conditions. Nutrient levels within the surrounding oceanic waters also appear to be sufficient to allow macroalgal growth and these levels are comparable between Tryphena and adjacent Great Barrier Island sites.  The nitrogen isotope values of Microdictyon do however suggest that anthropogenic sources periodically contribute to nutrient loading within the harbour.

10.     Overall, the results do not provide strong evidence that the proliferation of Microdictyon in Tryphena Harbour is due to elevated nutrient levels. However, the optimal physical conditions for seaweed growth within Tryphena Harbour mean that even relatively small amounts of anthropogenic-sourced nutrients will likely promote the long-term persistence and proliferation of Microdictyon within the harbour.



That the Great Barrier Environment Committee:

a)      Receive the report

b)      Explore the option of surveying potential anthropogenic sources of nitrogen within the harbor.

c)      Explore the option of including Marine water quality monitoring on Great Barrier Island which can be included in the regional Marine water quality monitoring program. This information will be highly relevant to inform marine water quality concerns and provide additional longer term data on nutrient status of harbour waters.

d)      Explore the option of including freshwater monitoring on Great Barrier Island which can be included in the regional Freshwater quality monitoring program. This information will be highly relevant to inform freshwater concerns and determine appropriate management response.

e)      Explore options to continue the monitoring of Microdictyon within Tryphena Harbor. Continued and more frequent collections of Microdictyon, and analysis of tissue %N and δ15N, would provide further insights into the importance of anthropogenic-derived nutrient sources in fuelling blooms within the harbor.



11.     The Great Barrier Island Local Board approached the Research, Investigations and Monitoring Unit (RIMU) to investigate the potential nutrient sources facilitating the growth of the green mossy alga Microdicyton umbilicatum. In previous years this alga has washed up on beaches in Tryphena Harbour following strong onshore (west to south-westerly) winds. Anecdotal evidence suggests the presence of this alga is a new phenomena and information describing the potential mechanisms underpinning the proliferation of this green alga were warranted. This information can be used to facilitate the identification of management options to best address this issue.

12.     At the start of this program it was assumed that the algal in question was Microdictyon muitable. After visual and genetic identification we are certain this green algal is Microdictyon umbilicatum. Microdictyon umbilicatum is non-toxic and not an invasive species. It is also found at Leigh, other Great Barrier Island locations, and in New South Wales, Australia.

13.     Extent of Microdictyon distribution

An underwater camera was employed to assess the extent of Microdicyton in Tryphena Harbour and at a number of additional Great Barrier Island sites. It was established that the majority of Microdicyton was located in Tryphena Harbour with small patches in Okupu Bay (only observed during 2012). Subsequent camera tows were conducted on 5 occasions (spring 2012, summer, winter and spring 2013, summer 2014) in Tryphena Harbour and at times the camera was towed from one side of the harbour to the other. Camera tows revealed Microdicyton to be widespread and in drifts up to 40cm in thickness during spring 2012 and summer 2013 (see Figure 1C). Microdicyton was found to be less widespread and less abundant in subsequent surveys. The highest quantities were generally observed in spring and lowest during winter. In February 2014 Microdictyon was sparse and mainly found in deeper water (>15m).

14.     Water quality monitoring (nutrients, sediments and turbidity)

To determine nutrient (nitrogen and phosphorous) concentrations in seawater at Tryphena harbour, water samples were taken at 4 sites during spring 2012, summer, winter and spring 2013 and summer 2014. Water samples were also collected at Whangaparapara (N1), Blind Bay (N3, N4), Schooner Bay (N5) and one location to the south (S2, see Figure 2). The rationale here was to sample seawater close to beaches and streams which would be more influenced by land based activates (and potentially contained higher levels of nutrients) and then compare these samples to seawater collected from the wider harbour, further offshore and at neighboring bays (see Figure 2).

Phosphorus and total inorganic nitrogen concentrations were similar across all sites monitored and there was no clear difference between Tryphena and adjacent sites. Some seasonal variations were observed, with the highest concentrations in winter and lowest in summer, which is typical for coastal sites. When compared to the Marine water quality program carried out throughout Auckland, these concentrations were similar to those observed at the most pristine locations on the mainland (Leigh and Ti Point). There were very small differences in nitrogen and phosphorous concentrations across all sites (Tryphena to Whangaparapara) indicating that Tryphena is not subjected to abnormally high concentrations of nutrients compared to other sites along the southwestern coast of Great Barrier Island. Interestingly the highest nitrogen concentrations were recorded at sites to the south of Tryphena, which are situated on the northern side of the Colville Channel and exposed to higher currents that likely drives localized upwelling.


Figure 1. Microdictyon umbillicatum at Great Barrier Island. (A) Aerial imagery (2008) showing large subtidal drifts of Microdictyon. (B) Drifts of Microdictyon on mega-ripple sand and (C) completely covering the sandy substratum in Tryphena (Oct 2012). (D) Microdictyon attached to subtidal rocky substrate at Katherine Bay (Oct 2012).


A                                                                                  B



C                                                                                 D



15.     Growth rates

Growth of rates of Microdicyton was measured by placing ~5g of Microdictyon in suspended mesh bags at depths of 7-9 m. This was undertaken at the 12 coastal sites showing in Figure 2. The mesh bags (see Fig 3) were deployed at each site for 14 days and the experiment was repeated on three separate occasions (summer 2013, and repeat trials in spring 2013). Growth rates were highly variable among the three time periods. In the first two experiments low rates of growth were observed, primarily due to the occurrence of large southwesterly storms and the loss of tissue from mesh bags.  Weather conditions were calm during the third trial (spring 2013) and there was consistent growth across all sites. During all three trials there was no evidence that growth of Microdictyon was higher in Tryphena. Growth tended to be higher at the southern-most sites, corresponding with higher concentrations of nitrogen in the tissue and higher nitrogen in seawater samples. Overall, the measured growth rates of Microdictyon were relatively slow compared to other nuisance algae such as Ulva in New Zealand and overseas.


Figure. 2 Microdictyon umbillicatum study sites at Great Barrier Island (see yellow, red and blue marks). Water quality was monitored at sites located along an onshore to offshore gradient (see white pins and white dashed box) Offshore, Harbour Mouth, Nearshore and Inshore (T2 and T3).


Tryphena Harbour



16.     Analysis of Microdictyon tissue

Chemical analysis of seaweed tissue provides a measure of the overall nutrient status of the plant (as indicated by the percentage nitrogen in the tissue) as well as the main sources of nitrogen (from stable isotope analysis). Stable isotope ratios such as δ15N (delta 15 N) are useful in identifying the main sources of nitrogen. No previous information is available on isotopic signatures of Microdictyon in New Zealand. In New South Wales, Australia Microdictyon has been developed as a bioindicator. This body of work indicates nitrogen from sewage inputs results in high δ15N values (> 12 ‰) while agricultural runoff had low δ15N (<6 ‰).


New Zealand's green seaweed Ulva from coastal sites with low catchment modification has a narrow range of δ15N values from 6.6 to 8.8 ‰. This range reflects δ15N estimates of dissolved inorganic nitrogen from oceanic seawater in the absence of terrestrial inputs of nitrogen. Barr et al (2011) suggest that deviations in Ulva tissue-δ15N values beyond the range’ of 6.6–8.8‰ is likely to reflect an influence of either anthropogenic nitrogen (e.g. wastewater or farming effluent) or other terrestrially derived nitrogen (e.g. from freshwater runoff). In the context of the present study Microdictyon tissue-δ15N allowed a broad assessment of the potential sources of nutrients that may be facilitating the growth of Microdicyton.


Microdictyon at Tryphena exhibited considerable variation in tissue-δ15N and %N over the sampling period. Autumn and winter tissue-δ15N was similar and generally in the ‘natural’ range expected (based on Barr et al 2013). However, tissue-δ15N was considerably higher in spring 2012 (~9.5‰), and to a lesser extent in spring 2013 (~9‰). These high δN15 values for Microdictyon at Tryphena may indicate a potential anthropogenic nutrient source.


The %N values recorded in Tryphena reflect a typical seasonal pattern with peaks in winter and minimum values in summer. The maximum values of 2.5-3% in winter are typical for coastal seaweeds and do not indicate nutrient enrichment. The %N values in summer (<1%) are also typical and potentially indicate nutrient limitation. Therefore, while tissue-δN15 values in spring 2012 are elevated and of potential concern, tissue-%N was relatively low suggesting that plants were not particularly enriched in nitrogen.


Algal tissue from the growth rate experiments also allowed for the comparison of δ15N between Tryphena and the surrounding bays. Overall δ15N values were similar across all sites during the growth experiments indicating that the source of nitrogen that Microdicyton was ulitilzing at that time was similar. These values were all within the ‘natural’ range suggested by Barr et al 2013.


Figure. 2. In-situ growth measurements of Microdictyon using suspended mesh bags.



17.     Summary

The concentrations of seawater nutrients, nitrogen and phosphorous, recorded in Tryphena Harbour are comparable to other sites on the southwest coast of Great Barrier Island and are not indicative of a nutrient enrichment problem. Growth rates of Microdictyon in Tryphena were also comparable to other surrounding locations. Tryphena Harbour is protected from large ocean swells and is typically bathed in clear oceanic waters. This unique environmental setting appears to allow Microdictyon to flourish in this relatively low nutrient system.


Isotope analysis allowed an assessment of the potential sources of nutrients fuelling the growth of Microdictyon at Tryphena and adjacent sites. Microdictyon tissue-δN15 from growth experiments at multiple sites in and around Tryphena showed that the nutrient sources did not vary among sites. This provides some evidence to suggest that the nutrients fuelling Microdictyon growth are primarily oceanic in nature. However, seasonal variations in δ15N signatures were recorded, with high δ15N values recorded in spring 2012.  Such high values of δ15N are indicative of anthropogenic sources of nitrogen and suggest Microdictyon are periodically ulitising alternative sources of nitrogen within Tryphena Harbour.  The extent to which such anthropogenic inputs contribute to the long-term persistence of Microdictyon requires further investigation, but action should be taken to minimise any anthropogenic inputs of nutrients that might facilitate Microdictyon blooms in this otherwise pristine environment.


Maori Impact Statement

18.     The environmental information obtained from the above programmes will be of interest and can empower Maori as Kaitiaki and Tangata Whenua. This report will also be of value to inform the Maori Plan and pertinent environmental indications that relate to water quality.

Implementation Issues

19.     NA




Dr Jarrod Walker, Senior Marine Scientist, Research, Investigations and Monitoring Unit

Dr Nick Shears, Lecturer, University of Auckland


Greg Holland, Manager, Research, Investigations and Monitoring Unit

John Nash - Senior Local Board Advisor


Great Barrier Environment Committee

26 March 2014



Great Barrier Environment Committee

26 March 2014



Community group and agency reports


File No.: CP2014/04230





1.       The purpose of this report is to provide a place where Great Barrier community groups and agencies with an interest or role in the environment or the work of the Great Barrier Environment Committee, can have items considered as part of the committee’s agenda.

Executive Summary

a)      At its 27 February 2014 meeting, the Great Barrier Environment Committee “agreed to create a community reports item on its meeting agenda to enable community groups and agencies with an interest in the environment on Great Barrier to have material formally considered by the committee noting that this approach may be discontinued at any time if the committee finds it necessary”.

2.       Although the preference is that reports be submitted in time for inclusion on the agenda, the option of material being pre-circulated to the committee and other interest groups is available at the chair’s discretion.

3.       The recommendation against reports included on the agenda will be that the report be received. It is up to the committee whether it wishes to pass any additional resolutions to action these requests if appropriate once it has considered the material provided.

4.       The items received and approved for inclusion on this agenda are attached to this report as outlined below.



That the Great Barrier Environment Committee:

a)      Receives the reports of the Great Barrier Island Environmental Trust on the Easter rat hunt and the Great Barrier island restoration project and the Department of Conservation’s agency report.








Great Barrier Island Environment Trust reports on the Easter rat hunt and Great Barrier Island restoration project



Department of Conservation agency report



Waste minimisation education update by Brigid Graney





Guia Nonoy - Relationship Manager PA/Office Manager


John Nash - Senior Local Board Advisor


Great Barrier Environment Committee

26 March 2014



Great Barrier Environment Committee

26 March 2014



Great Barrier Environment Committee

26 March 2014