A report by the Parliamentary Commissioner for the Environment Simon Upton describes estuary management as mind-bogglingly complex and constantly subject to change.
Managing our estuaries highlights a tangle of overlapping jurisdictions and responsibilities, ever-changing policies, and inadequate enforcement and compliance. The report calls for an approach that treats estuaries and the waterways that feed into them as a single entity from the mountains to the sea.
The SMC asked experts to comment on this report.
Dr Joanne Ellis, Senior Lecturer, University of Waikato, comments:
“The PCE report provides a needed overview of the issues facing New Zealand estuaries, which includes the need to manage pressures that cumulatively affect them. The report overviews issues related to the Resource Management Act 1991 and other legislative tools designed to control these pressures recommending the development of robust management framework/s that treat estuaries and their catchments as a single identity.
“As a scientist that has worked in estuarine and coastal environments for 20 years, I am very pleased to see the recommendation that ‘managing the activities that affect estuaries will mean considering all the activities that cumulatively impact on estuaries in an integrated way with climate change in mind’.
“Historically we have managed single pressures in isolation in coastal environments internationally and in New Zealand. However, estuaries experience multiple stressors that overlap in space and time and the interactions between pressures can yield unexpected results. Understanding how multiple pressures interact, whilst scientifically challenging, will be critical to helping us manage estuarine health.
“The Commissioner provides two high-level recommendations or potential leverage points to improve the health of our estuaries. Firstly, that estuaries be managed within one or more freshwater management units within the National Policy Statement for Freshwater Management. Secondly, that a robust monitoring system be established to help local government and communities make informed decisions including metrics based on mātauranga Māori.
“These recommendations are important steps towards improved estuarine health, however, they will require a high level of commitment to: a) understanding how cumulative stressors may impact estuaries working backwards from estuaries to identify the activities and pressures occurring in surrounding catchments, and b) a continued commitment to address hurdles to implementing good management in estuaries such as the current fragmented science, management and governance hurdles, diverse social values and conflicting and competing interests that New Zealanders have for our estuarine environments.”
No conflict of interest.
Professor Conrad Pilditch, Theme leader for Degradation and Recovery, Sustainable Seas National Science Challenge, comments:
“This report is sounding the much-needed call for action for this often-forgotten area. It clearly articulates that many estuaries are in trouble and that the current policy and management frameworks to address this are fragmented and disjointed. As the land-sea interface, estuaries are subjected to multiple stressors from all directions; and the cumulative effects of these stressors can cause rapid and unexpected degradation.
“The suggested solution of explicitly including estuaries within freshwater management will certainly help regulate land-derived stressors such as sediments and nutrients – which is critical for estuaries to recover. However, just ‘turning off the taps’ won’t be enough because many stressors occur in the estuary itself or come from the open ocean, and legacy effects may slow recovery. This is especially true when considered against a background of climate change affecting our oceans and coasts.
“The report calls for national standardised approaches, something many scientists and marine managers have been saying for a while. Estuaries are currently managed in piecemeal way, and our research has highlighted that most monitoring programs are unable to detect indicators of approaching tipping points.
“Although the report doesn’t call for ecosystem-based management (EBM) by name, the holistic integrated approach with decisions informed by science and mātauranga Māori has the attributes of an EBM approach which the Sustainable Seas Challenge strongly supports.”
No conflict of interest.
Dr Viktoria Kahui, Senior Lecturer, Department of Economics, University of Otago, comments:
“Managing our estuaries is a timely report by the Parliamentary Commissioner for the Environment highlighting the decline in quantity and quality of wetlands, marshes and estuaries around New Zealand (and worldwide), which are known hotspots of biodiversity, recreation and mahinga kai.
“I think the report is well written, clear and concise. More and more we are coming to understand the complexities involved in managing ecosystems, the effects of cumulative impacts from pollution and climate change, and the effects this has on estuaries over time. The report clearly outlines the main drivers and the problems of overlapping jurisdictions, stakeholders and legislation, and makes two ‘modest’ recommendations: we need integrated management of estuaries, and we need better monitoring.
“One of the key issues, as the report points out, is that integrated policy making is difficult. The designation of a landfill further inland may have repercussions for the effluent discharge into an estuary kilometres away, but the decision making processes are often disparate.
“The report makes the point that the struggle for integration is a Pākeha problem; fragmented ownership is a legacy of Western society. The Māori notion of ki uta ki tai (from the mountains to the sea) represents a holistic worldview that focuses on the mauri, the life force of a place, as an indicator of ecological health.
“The report points out that attempts to incorporate Māori concepts into current legislation have been ‘fraught with difficulties’. On p. 59, it states ‘A holistic way of thinking has been compartmentalised into the various laws that govern estuaries, making it difficult to manage them according to interconnected Māori values.’
“The report provides a shortlist of initiatives to protect estuaries, including the mandatory inclusion of estuaries as part of the National Policy Statement for Freshwater Management (NPS-FM), the addition of marine species to mahinga kai, the addition of attributes for estuaries to the NPS-FM and robust monitoring efforts.
“These recommendations are an important first step, but fall short of truly integrated management. This is where I would have liked to see much more direction and discussion. How can we move beyond separate spatial and legislative frameworks to something akin to ecosystem based management in the spirit of Te Ao Māori? How about legal personhood?
“In 2017, the New Zealand Parliament granted the Whanganui River legal personhood, thereby recognising the River as ‘an indivisible and living whole comprising the Whanganui River from the mountains to the sea’. The human face of the legal entity is comprised of a person appointed by the Crown and one by the Whanganui Iwi, supported by an advisory group a strategy group comprising representatives of iwi, central and local government, and other groups with interest in the River, such as tourism, conservation, recreation, wild game and hydropower.
“This very much fits the notion of ki uta ki tai, and may well be an option for estuaries, but very little discussion in the report is devoted to integrated management processes.”
No conflict of interest.
Professor Simon Thrush, Director, Institute of Marine Science & George Mason Centre for the Natural Environment, University of Auckland, comments:
“It is good to see this national focus on our estuaries and how our governance for these ecosystems is failing them. As the report recognises, our culture and history is closely linked to estuaries, they have been important food baskets, settlement sites, ports and accessible wild places for recreation.
“The report reveals massive gaps in our knowledge-base and governance structures that requires a major re-think.
“Estuaries and harbours are critically important ecosystems, squeezed between the land and the sea they are subject to impacts from both (although the report focuses mainly on the land-based impacts). They deliver a range of increasingly important ecosystem services.
“The report identified many problems with our estuaries, but it is light on solutions. This is a difficult task but I was hoping for a bit more of a revolution than business as usual. If you want to fix these systems we need to know how they work, and the report does not address the information we have that goes beyond a description of state to address how they function and how these functions are impacted by human activities.
“The report recognised the significance of cumulative effects in estuaries. Cumulative effects are likely to generate tipping points in these ecosystems; these surprising changes challenge our current management practice and highlight the importance of retaining ecosystem resilience. Cumulative effects mean that we need to consider more local and multi-scale management strategies rather than simplistic one-size-fits-all national standards. It is critical to develop ecologically credible ways to beyond our usual – one stress at a time please – management.
“The recognition of the importance of cumulative effects also offers some important opportunities. For example, it draws us away from thinking there is a silver bullet fix to estuarine management and forces us to accept that this is a wicked problem.
“Furthermore, the report also touches on some of the likely impacts of climate change and questions whether we should walk away from these systems given the potential for future change. In estuaries the effects of ocean acidification are much more strongly linked to local processes such as loss and change of habitats and eutrophication than to ocean pH. These effects could be managed at a local scale. A critical element in developing a realistic strategy for cumulative effects management will be recognising what we can address local or nationally and manage those factors to offer the estuary system the adaptive capacity to cope with the change we cannot manage.
“While the report touches on climate change, it pays no attention to our other major challenges associated with biodiversity loss and ecological sustainability. This is a shame because as the report points out, fixing up a damaged system is no easy task. But that does not mean we should treat these ecosystems as too hard to fix.
“The report pays scant attention to our understanding of the importance of these ecosystems to biodiversity and ecosystem function. Healthy estuaries are highly productive ecosystems supporting both primary and secondary production and thus supports many important shellfish, fish and shorebirds. Estuaries play critical roles in in processing and removing some of our major contaminates, such as nitrogen. They and the adjacent shallow coastal marine sediments are globally significant locations for denitrification and the breakdown and remineralisation of organic material.
“[The attached diagram] is a standout figure of the report. This figure does not address the ecosystem process or human stressors in the ecosystem, rather it basically defines our current model of governance. No wonder we are in trouble. This description is more akin to swimming though mud than a strategy to manage cumulative effects, triage our sick estuaries, and actively reverse the decline in biodiversity and critical ecosystem services.
“The report makes two recommendations: Firstly linking the management of estuaries to freshwater standards. I think this is a mistake. The effects of human impacts in rivers and streams does not map well to impacts in estuaries. The strength, extent, and duration of effects are very different. As the report rightly identifies, it is cumulative effects that we must manage in estuaries and these effects are a product of what happens in the estuary, the adjacent coastal ocean as well as from land. Managing estuaries as part of the catchment is only part of the problem. We also need to manage them in the face of changes in-estuary (fishing and aquaculture) and in the interconnected coastal ocean – water flows two ways in an estuary not just downhill. We need some joined-up thinking and actions. To fix the problems with our estuaries, a much more ecosystem-based, simple and action-based management is needed rather than a bureaucratic tweak. Let’s not forget that estuaries are largely marine ecosystems, especially in New Zealand because of our tidal range and typically short and flashy rivers. This means that their ecologies are largely marine not stream and they need to be managed with that in mind.
“Secondly, the report calls for national monitoring. Good data will help us track trends without doubt and help us understand the changes that are outside of normal. But this is not enough, where we do have data we do not have the strategy and activities to reverse the well documented negative trends. Ecosystem-relevant data collected at scale is possible and implementable but this needs to be prioritised and associated with an action-based research strategy and governance processes that can quickly respond to adverse effects and broader environmental change.
“The report values an independent assessment of monitoring. This is critical for ensuring that it is both fit for purpose and has the capacity to develop with scientific and technical advances. Let’s extend that to the effectiveness of estuarine and coastal management.
Conflict of interest statement: “I have conducted research and works with management agencies on estuaries over 30 years. I have offered advice to the Commissioner on ecological monitoring in estuaries that contributed to a previous PCE report. I have contributed my knowledge of interactions in estuaries, stressor effects and cumulative effects to the Bayes Net model of cumulative effects in estuaries produced by NIWA Hamilton and briefly referred to in the Estuary Report.”
Dr Candida Savage, Department of Marine Science & Portobello Marine Laboratory, University of Otago, comments:
“The PCE report, Managing our estuaries (released in August 2020), outlines two recommendations: firstly to develop a management plan that treats estuaries and their catchments as a single identity, and secondly to ensure we monitor these ecosystems appropriately with high-quality data to inform decision making.
“These recommendations are timely and pressing as the effects of cumulative stressors increasingly compromise the ability of New Zealand’s 400+ estuaries to deliver the goods and services that humans rely on.
“The first recommendation considers that estuaries are the confluence between land and the coast and recognises that activities on land affect estuaries. Estuaries receive inputs of nutrients and sediments from surrounding catchments, with often subtle additional stress causing an estuary to show signs of degraded health (for example, loss of shellfish beds; blooms of nuisance seaweed).
“Importantly, while the effects of single stressors are well studied, there is still a major knowledge gap in how multiple stressors act together (cumulative stressors) to influence estuarine health. The interaction between stressors is not merely additive but the interaction can yield unexpected tipping points in the structure and functioning of estuaries. The interaction of these stressors is difficult to predict, yet is urgent as the effects of climate change (including warming seas) are likely to overlay local stressors.
“Once estuaries have transitioned into a different state, the effort needed to reverse it is often greater and there is a lag response before management interventions show a positive outcome.
“The second recommendation highlights the need to robustly monitor estuaries so that managers understand trends in the health of their systems and the processes and feedbacks that can lead to loss of functioning. The report acknowledges the need to bridge mātauranga Māori and science to advance our understanding of these ecosystems that have a long history of cultural, economic and ecological significance.
“The report uses five different model estuaries as case studies to highlight the complex issues around managing New Zealand’s estuaries. A key challenge in estuarine management is that it requires managing the human activities that affect the estuary rather than simply managing the body of water. Accordingly, management agencies need to consider the legacy of stressors from the land that drains into estuaries as well as pressures in the estuary itself (for example, collection of shellfish) and global pressures (climate change).
“The report highlights how estuaries have typically ‘fallen through the cracks’ in terms of legislation. Estuaries were identified as important ecosystems to manage as their own entity as recently as 2010 in the New Zealand Coastal Policy Statement 2010. The National Policy Statement for Freshwater Management (which had its fourth iteration released in 2020) recognises the connection between land, water and human health and an integrated approach to managing freshwater by considering catchments in the management of estuaries.
“While a few regions (and here the report outlines Southland as making positive strides) have recognised the connection between freshwater and coastal environments, there are still few benchmarks for how to manage estuaries and give credence to managing the effects of land-based activities for estuarine health.
“The Managing our estuaries report makes an urgent bid for estuaries to be included in freshwater management units to facilitate integrated management from the mountains to the sea (ki uta ki tai) and ensure these valuable ecosystems continue to weave a future that sees the landscape and the people within it inseparable.”
No conflict of interest
Dr Andrew Swales, NIWA Principal Scientist and Programme Leader – Catchments to Estuaries, comments:
“The PCE’s investigation of the state of New Zealand’s estuaries is very timely. Our estuaries have been transformed in only the last 150 years or so. Catchment deforestation, subsequent development of pastoral agriculture, urbanisation and land-use intensification in recent decades have been the major drivers of environmental degradation. Receiving estuaries have infilled with eroded soils, nutrients and stormwater pollutants. Sedimentation rates that are ten-fold higher than prior to catchment disturbance have transformed many estuaries from sand- to mud- dominated, highly turbid, systems. The development of tidal mudflats and expansion of mangrove habitats in our northern estuaries over the last century are obvious signs that all is not well.
“Below the surface, and less obvious to the casual observer, is the impoverishment of ecosystems and the services they provide due to the loss of habitats and their pollution-sensitive species (e.g., seagrass, shellfish). This problem of a gradually shifting environmental baseline is not well recognised.
“NIWA supports the main conclusions of the PCE report. Integrated catchment-estuary management informed by high-quality monitoring data that is operationalised in resource management will enable meaningful improvement in the state of New Zealand’s estuaries. The fragmented nature of land tenure, land use management and poor accounting for the cumulative effects of human activities in resource management are major challenges to address. Sustaining or restoring estuarine habitats, ecosystems and the services they provide to New Zealand society will be difficult to achieve otherwise.
“The PCE’s recommendation for improved and nationally consistent estuary monitoring should be supported. Replacing the present ad hoc approach to monitoring with monitoring systems for estuaries (ideally using standardized methods and metrics) needs to be implemented and integrated with freshwater monitoring systems.
“The shift in emphasis from effects- to limits-based management for freshwaters and estuaries announced in MfE’s recently released ‘Action for healthy waterways’ provides a policy framework that could address the ongoing degradation of estuaries. Limits-setting is to be enacted in regional plans by 2026. It is unclear yet how regional councils will achieve this, in general making limited progress to date in this fundamental transformation to limits-based management regime.
“Finally, the PCE rightly identifies that climate change impacts, such as changes in freshwater flows, diffuse-source contaminant loads (including sediments, nutrients and urban stormwater), storm frequency and intensity, as well as the unavoidable and approaching ‘freight train’ of sea-level rise will magnify the issues and pressures already facing New Zealand’s estuaries.
“New Zealand has much of the science know-how needed to transform the way we manage estuaries – improved coupling of this research capacity with councils and communities to achieve the outcomes we seek is pressing.”
No conflict of interest
Dr Scott Larned, NIWA Chief Scientist, Freshwater and Estuaries, comments:
“Environmental scientists in New Zealand are acutely aware that estuaries lag behind rivers and lakes in terms of regulatory protection. The new PCE report should make estuaries more visible to policy makers and reduce the gap. The report has two specific recommendations: the inclusion of estuaries in freshwater management units’ (FMUs) under the National Policy Statement for Freshwater Management 2020 (NPS-FM), and mandatory estuary monitoring programmes.
“NIWA supports these recommendations and commends the PCE for setting them out in a compelling way, but the scope of each needs be expanded if we are to prevent and reverse estuary degradation.
“By requiring their inclusion in FMUs, estuaries will be ensured the same level of regulatory protection as freshwater bodies in the current NPS-FM. That is, limits on resource use (and ‘action plans’) will be required to ensure that estuary objectives are achieved. Those objectives are to be based on values such as mahinga kai, ecosystem health and water quality. The work to bring estuaries up to the same level as freshwater bodies in the current NPS-FM should not be onerous. Communities and iwi/hapū are ready to identify values in their estuaries, and scientists are ready to develop ‘bottom-lines’ for estuary values.
“The real challenge is not about estuary values, it is about setting limits. Limit setting in the NPS-FM refers to discharging contaminants such as sediment and nutrients into water bodies, and water abstraction from water bodies. Using limits to achieve estuary objectives assumes that we can accurately predict how resource use on land will affect values in often distant estuaries. In reality, our current predictive power is limited, and this is one of the main impediments to implementing the NPS-FM. What is needed are chains of predictions that link different types of resource use to the catchment processes that deliver contaminants and water to estuaries, and then to the effects on different estuary values.
“The second PCE recommendation is for mandatory monitoring. Environmental monitoring is costly, but the need for monitoring data is inarguable, and we commend the PCE for making that clear. However, monitoring alone will not be adequate, as limit setting is based on cause-and-effect predictions, not raw data. Furthermore, current monitoring in both freshwater and estuaries focuses on aquatic values, not the drivers of degradation such a land use intensification and overfishing.
“And here is where the two PCE recommendations come together: limit setting to achieve estuary objectives will require quantitative models that predict the effects of land-based resource use on estuary values, and the models will require monitoring data for both values and drivers.
“Modelling may sound esoteric, but it is the most practical way forward for three reasons: 1) models will help focus management actions on the primary causes of estuary degradation; 2) models will provide predictions for unmonitored and under-monitored estuaries; 3) models will provide a means of forecasting the effects of future changes in land use and climate.”
No conflict of interest
Dr Chris Cornelisen, Group Manager, Coastal Sciences, Cawthron Institute, comments:
“Cawthron Institute welcomes the findings of the Parliamentary Commissioner for the Environment’s ‘Managing Our Estuaries’ report because they demonstrate the many ways estuaries have ‘fallen through the cracks’ of New Zealand’s environmental monitoring and management frameworks.
“Cawthron supports the PCE’s call for estuaries to be incorporated into the National Policy Statement for Freshwater Management (NPS-FM) because this would ensure there were clear guidelines and standards for protecting the health of estuaries.
“There are alternative options that could be pursued in establishing policy settings, and the mechanisms that might be used (e.g. develop an entirely separate national policy statement for estuaries, modify an existing policy to include a national objectives framework for estuaries, or look at legislation and policy alternatives from around the world), however we agree with the PCE’s assessment that the NPS-FM already includes most of the mechanisms that are needed to manage estuaries effectively and consistently across New Zealand.
“Cawthron also supports the PCE’s call for consistent and robust monitoring of estuaries across New Zealand. The truism ‘you can only manage what you measure’ applies in the case of estuary monitoring in New Zealand and how we measure is really important. Estuary monitoring to date has been largely focused on the benthic environment – this means it has been focused on looking at what kind of life there is in the estuary bed and how much there is. This is a really good indicator of whether the ecosystems that the estuary supports are in good health. Although this information is important, it is not all we should be monitoring. Little attention has been given to developing an understanding of the relationships between the health of streams and rivers (including catchment stressor loads) and the health of our estuaries and coastal habitats. This has resulted in a serious gap in our ability to manage freshwater and coastal water quality and understand the relationship between the two.
“The results of estuary monitoring across the country are likely to be different, but the methods used to obtain those results should be the same. For example, water quality will naturally vary from estuary to estuary because of the unique characteristics and conditions each has. There needs to be robust and long-term data collected for each estuary based on factors like estuary type, freshwater inflows, tidal flushing rates and water quality. Monitoring methods for estuary health should be standardised across New Zealand to allow for cross-regional and national comparisons. This would support the establishment of new policy settings for estuaries, and enable estuary managers to meet existing policy requirements, such as the reporting required under the Environmental Reporting Act (2015).
“Cawthron scientists developed the original estuary monitoring protocol that is still used by local authorities today, however the protocol has evolved over the past 18 years and needs to be updated, improved and further standardised, particularly with respect to the development of indicators that will support the development of policy settings. We are eager to support the development of assessment methods that are feasible to implement all over New Zealand. Because we think molecular technologies should be a core component of these methodologies, Cawthron has continued to make significant progress in the development of estuary-specific eDNA health assessment tools and research that will help link the health of estuaries to their upstream sources.
“Cawthron, NIWA, and the University of Waikato have also recently released a new tool called the National Benthic Health Models which can be used to assess the health of any estuary in New Zealand. The National Benthic Health Models use information about the animals living in the seafloor sediments of our estuaries (e.g. worms and shellfish) to assign a score which indicates the health of the estuary in response to the two key coastal stressors – sedimentation and heavy metal contamination.
“We think high priorities for research include the development of indicator health thresholds for different estuary types in different locations and investigation of reference estuaries (i.e. those in the most pristine state). We also need to consider how climate change is affecting our estuaries now and start planning for the future, for example, by mitigating the effect of human impacts such as water abstraction, which is where freshwater is taken from the catchment, reducing the amount that makes its way to the sea. The old Kiwi adage that ‘water left to flow out to sea is wasted water’ is one example of a widely-held belief by land and freshwater managers that has significantly impacted estuarine health and thus far been unaccounted for in freshwater management practices.
“Cawthron strongly advocates for the development of an open-access database for estuary monitoring data. Better access to monitoring data would help with the development of national guidelines, enable estuary managers to assess their estuaries in the context of New Zealand and facilitate national-scale research. It would also enable better coordination of State of Environment and consent-related monitoring. Some progress has been made towards collation of national level data, but the next step should be to create a database that is continuously updated as new monitoring data becomes available. Possible options for hosting the database include a coastal module in LAWA, the LINZ Marine Geospatial database or the DOC Estuaries Hub. Funding would be required to maintain the dataset including metadata, methods, quality control procedures and supporting documentation.
“As a small nation, New Zealand has a unique opportunity to achieve consistency in the monitoring and evaluation of estuaries. Given the limited funding for coastal assessment, it is vital that we maximise the information that can be gained from the data that we are collecting as well as our ability to interpret this data in the context of estuary health. Aligning monitoring and evaluation methodology, calibrating indicator thresholds in relation to estuary health, and ensuring resulting data is available for research and wider-scale assessment purposes would be a good first step toward achieving this. Ultimately, national policy direction is required to help ensure estuary health is maintained or improved so we can continue to benefit from the ecosystem services that estuaries provide.
“Currently, there are no government policies that require councils to explicitly account for estuary health. The New Zealand Coastal Policy Statement (NZCP, 2010) guides local authorities in their management of the coastal environment (including estuaries) but fails to provide strict definitions of estuary health and guidelines on limits and standards to maintain or improve health. The National Policy Statement for Freshwater (NPS-FM, 2014) specifies that managers need to consider the receiving environment but does not provide guidance on how to achieve this, nor does it consider pressures that are not related to freshwater inputs. Without explicit guidelines and standards for protecting the health of estuaries, these important and vulnerable ecosystems, which are the receiving environments for a range of pollutants, are falling through the cracks.
“Councils should be required to explicitly include the protection of estuaries in regional plans with the identification of objectives as well as measures and timescales for achieving these objectives. This requirement could be achieved through the development of a National Policy Statement for estuaries or modification of one of the existing policy statements (NZCP, NPS-FM) to include a National Objectives Framework (NOF) for estuaries. Alternatively, guidance could be taken from legislation and policy documents developed overseas (e.g. river basin management plans required under the EU Water Framework Directive, 2000; US National Estuary Program under the US Clean Water Act, 1972), which manage water bodies on a river basin or catchment scale, ensuring that guidelines achieve good health from the mountains to the sea. Of the various ways that New Zealand’s estuaries could be offered more protection through policy, the PCE recommends including estuaries in the NPS-FM, because it already includes the types of mechanisms that are needed to manage estuaries effectively and would also reduce silos rather than reinforce them.
“To support new policy, monitoring methods would need to be standardised. Alignment of methods and protocols would also help to meet existing policy requirements, such as the reporting required under the Environmental Reporting Act (2015) (e.g. Dudley and Jones-Todd, 2018; Ministry for the Environment and Statistics New Zealand, 2016). National Environmental Monitoring Standards (NEMS) are already underway for key coastal water quality parameters but little progress has been made for benthic indicators. The Estuary Monitoring Protocol (Robertson et al., 2002) that most councils follow for benthic monitoring is not sufficiently detailed to ensure consistency across providers and there is no agreement on which methods are preferable. Berthelsen et al. (2017), Bolton-Ritchie & Lawton (in draft) and Hewitt et al. (2014) have documented the inconsistencies in estuary monitoring methods used by regional councils and these reports provide a useful starting point for the development of NEMS for benthic estuary health. Aligning methods would allow the monitoring data to be more fully utilised for research purposes and enable cross-regional and national-scale comparisons of estuary condition, although changes may come at the cost of comparison with historical data in some places. For national reporting, further consideration may need to be given to which estuaries are surveyed (e.g. per region and estuary type), site locations within estuaries and minimum survey frequency (see recommendations by Dudley et al., 2017 for coastal water quality monitoring). Consideration should also be given to incorporation of new technologies for assessment (e.g. Cawthron is currently developing molecular tools for estuary health assessment).
“Estuary monitoring to date has been largely focused on the benthic environment. In most instances, little attention has been given to developing an understanding of the relationships between estuary water quality and ecosystem health. This has resulted in a serious gap in our ability to appropriately manage the freshwater/coastal water quality continuum. Estuarine water quality characteristics can be highly variable depending on local conditions; e.g. estuary type and tidal flushing rates. Robust long-term data sets are therefore required to determine site-specific relationships between freshwater inflows, estuarine water quality and ecosystem health. Standardisation of monitoring designs to this end will be essential to achieve national context.
“Progress towards the identification and development of indicators for estuarine health has been advanced in New Zealand (e.g. Berthelsen et al., 2018a; Clark et al., accepted; Cornelisen et al., 2017; Dudley et al., 2017; Robertson et al., 2016a; Robertson et al., 2016b; Rodil et al., 2013; Zaiko et al., 2018). For assessment methods to be most useful they should be (1) ecologically relevant, (2) feasible to implement, (3) linked to threshold or reference values so that users can assess the significance of an indicator value, (4) sensitive enough to measure status or trends that are relevant to policy decisions and reflect responses to management actions, and ideally, (5) applicable over wide spatio-temporal scales (Borja and Dauer, 2008).
“High priorities for research include the investigation of reference estuaries (i.e. those in the most pristine state) and the calibration of indicator health thresholds for different estuary types/parts of the estuary/regions. Consideration should be given to what our estuaries may look like under future climate change and the effects of human impacts likely to become more prominent in the future (e.g. water abstraction). Development of spatially explicit descriptor variables for estuaries, like those available for freshwater bodies (e.g. the Freshwater Ecosystems of New Zealand and River Environment Classification databases), would help with the development of predictive models for understanding current state and future scenarios.
“Further research is also required to understand connections between freshwater health/catchment stressor loads and estuary health, in order to ensure that limits set for freshwater (under the NPS-FM) also protect estuarine values. The Ministry for the Environment-funded ‘Managing Upstream’ project, which identified attributes and indicators of estuarine state, reviewed available data and monitoring methods and identified data gaps, was a good first step in this direction (Cornelisen et al., 2017; Zaiko et al., 2018). The next step should include the identification of critical thresholds, provision of baseline and reference information and the development of tools to assist with making management decisions.
“Better access to monitoring data would help with the development of national guidelines, enable estuary managers to assess their estuaries in the context of New Zealand and facilitate national-scale research. It would also enable better coordination of State of Environment and consent-related monitoring. Some progress has been made towards collation of national level data. For coastal water quality, State of the Environment data has recently been compiled by Dudley et al. (2017) through funding by the Ministry for the Environment. The Department of Conservation has an interactive map of seagrass and mangrove extent. The Oranga Taiao Oranga Tangata research programme has compiled an open-access National Estuary Dataset, containing fine- scale benthic monitoring data from 409 intertidal sites across 70 estuaries from 2001- 2016 (Berthelsen et al., 2018b). The hard work undertaken in compiling this dataset should be leveraged, with the next step being the creation of a database that is continuously updated as new monitoring data becomes available. Possible options for hosting the database include a coastal module in LAWA, the LINZ Marine Geospatial database or the DOC Estuaries Hub. Funding would be required to maintain the dataset including metadata, methods, quality control procedures and supporting documentation. Coastal managers (i.e. Coastal Special Interest Group) are supportive of such an initiative but are struggling to identify and secure appropriate funding. The key issue likely to arise is around differences in taxonomic resolution between providers but this may be partially resolved by a proposal for a ‘Coastal taxonomic resource library for soft sediment macroinvertebrates’ being submitted for possible Ministry of Business and innovation Envirolink Tool funding.
“Future management of estuaries will be shaped by climate change, which is expected to cause pervasive changes, such as inundation of present-day intertidal areas and squeeze on coastal habitats as well as the impacts of changing water and air temperatures, ocean acidity and weather on estuarine connectivity, productivity and biodiversity. Monitoring protocols and estuary objectives need to be future-proofed by taking these changes into account, including the likelihood that existing monitoring sites may become progressively more subtidal, with implications for the use of macrofaunal health indices. With this in mind, it may be useful to consider the inclusion of subtidal data in a national database as this information may increase in relevance in the future. Besides focusing on the management of estuaries in relation to setting guidelines and monitoring (as discussed in this document), it would also be prudent to allocate resources for research into restoring estuaries and increasing their resilience to present- day and future stressors.”
No conflict of interest