4 Whole systems understanding and adaptive management
Even though the focus of this report is to recommend on short-term management options to address the symptoms of algal blooms in Lakes Rotorua and Rotoiti, it is important to place this work in the context of a 'whole systems' approach. This is because in complex natural systems many factors interact with each other and it is important to understand how changing one aspect could affect another aspect.
Equally it is important to look at all of the issues and processes in a system, even when considering just 'short-term' aspects so that any short-term management measures that are being considered are placed in the range and sequence of all of the proposed management measures.
It is also vital to understand all of the elements and interactions of the system that will be important for management. There are many examples around the world where incomplete understanding has led to costly and environmentally damaging mistakes.
Finally, it is important to get in and manage those issues that can be managed in the short-term because there is enough understanding to provide confidence that the proposed management will succeed. These three important principles or processes are discussed in more detail below in relation to the problems in Lakes Rotorua and Rotoiti.
4.1 Whole systems and understanding
Appendix 3 is a foldout graphic which shows a 'whole system' approach for Lakes Rotorua and Rotoiti. This diagram and the processes that interact between and within the lakes and the catchments lead to both the understanding that is necessary for management, and the prioritising of management options over the short (1-2 years), medium (2-4 years) and longer term (more than four years). In particular, they lead to the recommendations for short-term studies where there are critical gaps in understanding and the recommendations for short- and medium-term management measuresthat are set out in section 7.
Lakes Rotorua and Rotoiti are closely interconnected by the Ohau Channel and some 50% to 80% of the nutrients going into Lake Rotoiti come from Lake Rotorua. Lake Rotoiti's catchments are relatively small and there are relatively low levels of intensive land use, whereas Lake Rotorua has nine major catchments with significantly more intensive land uses. Thus for short- and medium-term management measures the focus needs to be on Lake Rotorua and its catchments.
Appendix 3 shows that two levels of understanding are needed; an understanding of the processes in the catchments that cause the nutrient inputs to the lakes and an understanding of the processes in the lakes that mobilise the nutrients and cause the algal blooms. These processes are discussed in more detail in section 7 as they lead to the specific recommendations in that section.
Research and investigations are normally tailored to provide the level of understanding necessary to trial or implement management options. The role of the responsible manager is to ensure that limited public funds are focused and used wisely to produce the required level of understanding, and EBOP is doing a good job in this respect, although a recommendation for some fine-tuning is made in section 7.
Whether or not further research is done to more completely understand particular systems is a matter for negotiation and availability of funding. Often management specific applied research is carried out as part of a larger package of broader research, with multiple funding to develop a much fuller understanding of the system. This is valuable and can lead to better goals and targets for parts of the system, but the prime concern of the manager will always be to understand the system enough to sustainably manage it for agreed goals and outcomes.
4.2 Adaptive management
Adaptive management is a process by which understanding of systems is iteratively used to apply and test management approaches until the best set of management options is reached. It is based on the principle that in most cases there will never (within reasonable costs and timeframes) be a 'complete' understanding of complex systems and that it is much better to build understanding by a combination of targeted investigations and adaptive trials of management approaches. Or, to put it crudely, it is very much the 'suck it and see' approach, but never jumping so far ahead that real problems occur.
In the case of Lakes Rotorua and Rotoiti, the steps for adaptive management could be:
- Understanding - do we know enough to understand a process or set of processes - within reason?
- Management - do we have enough confidence to test some management options and measure how they perform?
- Trial management - where we carry out larger scale trials and measure the effects and responses
- Sustainable management - when the agreed management option is implemented, but is then monitored and fine-tuned if necessary.
Using this process and agreeing on the best management options over time as adequate understanding is developed, will result in a sequence of management decisions and implementation of agreed management measures over the short, medium and longer term.
The recommendations in this report for short-term management options to tackle the symptoms of the recent algal blooms must be seen in this context as part of a whole system approach, and not just a kneejerk reaction to a problem over one summer. It is also vital that short-term management options are not seen as an excuse for delaying or avoiding longer term and possibly harder measures that need to be undertaken to restore and manage the lakes to agreed water quality and ecological standards.
