Benefits of marine protected areas
Marine protected areas can have a range of ecological, social, cultural and economic benefits, which are summarised below. The extent to which these benefits can be achieved in practice, is largely dependent on the location, design and on-going management of the areas.
Protection of biodiversity and increased productivity
Somewhat surprisingly, there have as yet been no studies in New Zealand to establish the direct impact of marine reserves on biodiversity. However, research has conclusively shown that, where extractive activities are prohibited, abundance of previously exploited marine species in marine reserves can increase dramatically, and that this can occur within relatively short periods of time.
An increase in the abundance of previously fished species can have a positive flow-on effect, through rebalancing predator-prey relationships, and overall the food web. For example, the increase in snapper and rock lobster within the Cape Rodney-Okakari Point marine reserve was associated with a marked decrease in the abundance of sea urchins (on which snapper and rock lobster prey), and a regeneration of kelp beds (on which the sea urchins prey). This, in turn, is thought to have increased productivity and diversity within the marine reserve. This is because kelp forests are major primary producers, support a richer and more diverse faunal community, and are “central to ecosystem function and diversity.” Scientists have estimated that macroalgae primary productivity in the reserve has increased by 58 per cent over a 20 year period. 2694
Increased resilience and maintenance of ecosystem services
Well-designed marine protected areas can help to promote healthy ecosystems which are resilient, and able to adapt to stresses, because they are complex systems with inbuilt buffers. Resilience enables marine communities to better withstand pressures whilst still retaining their basic function, including the delivery of the ecosystem services upon which we all rely. 2695 Critical services include climate regulation, oxygen production, nutrient recycling and production of protein for human consumption.
Benchmarking of environmental health
The complexity of marine ecological dynamics makes it hard for scientists to assess the impact of human-derived pressures on the marine environment.
Modelling can assist, but cannot provide all the answers. The establishment of areas in which specific activities are excluded, can play an important role in providing ‘benchmarks’ or ‘controls’, against which human impacts and management of the rest of the marine area can be evaluated.
In particular, because marine reserves exclude fishing, they can provide useful information on the characteristics of an unfished population, which can then be compared with those of the fished stock. This can provide an indication of the extent of change caused by fishing, and therefore help inform fisheries sustainability decisions. 2698
Marine protected areas can potentially benefit commercial and recreational fishers by contributing to fish stocks outside the protected area. This can occur if harvestable-size stock moves from the closed area to open areas where they can be caught, or if eggs and larvae cross the boundary and establish outside the closed area.
The spillover of harvestable species from reserves is evident from the presence of fishers around the edges of the protected areas. For example, cray pots often line the reserve boundaries around the marine reserve at Leigh.
The likelihood of such ‘spill-over’ depends on the mobility and habits of the species concerned, conditions inside and outside the marine protected area, and the area’s design (for example, longer edges enhance the likelihood of spill-over).
Marine reserves can support denser populations of larger fish for resident species that are heavily fished.
A recent study of three marine reserves in the Greater Hauraki Gulf (at Leigh, Tāwharanui and Hahei) found that there were on average 13 times more large snapper, above the legal size limit, within the reserves than outside them.
This has important implications for reproduction. Larger fish can produce far more eggs, per unit of body weight, than smaller fish. In addition, there is evidence that the larvae produced by larger fish have better survival rates.
A genetic study of adult and juvenile coral trout and stripey snapper within the Great Barrier Reef Marine Park demonstrated that the reserves contributed a greater proportion of the juvenile fish in fished areas than their size would indicate. The six reserves in the Keppel Islands comprised around 28 per cent of the reef habitat in the region but supplied around 50 per cent of the total recruited fish. The scientists concluded “our findings indicate that adults in reserves were making a large contribution to the replenishment of populations on both reserve and fished reefs”. 2706 Recent research at the Cape Rodney - Okakari Point marine reserve supports these findings, indicating that snapper larvae from the reserve make a strong contribution to surrounding fished stocks. 2707
Protection of geological features or processes
Marine protected areas can be used to protect geological features and processes identified as particularly unique or typical. This may be closely interlinked with the protection of the biodiversity they support. For example, deepsea vents are valued both as rare geological features and for the unique ecological communities which are dependent on them.
Protection of cultural values
The protection of marine space can be of considerable cultural value. For example, the establishment of the Whanganui A Hei – Cathedral Cove marine reserve was supported by Ngāti Hei, because the area included tapu sites associated with tribal massacre. Ngāti Hei believed that the establishment of the reserve enhanced their mana. Likewise, the Sugar Loaf Islands marine protected area includes tapu sites for at-sea burials.
The local hapū at Whangara (Ngāti Konohi) supported the establishment of Te Tapuwae O Rongokako Marine Reserve and joined with the Department of Conservation to make the application. The reserve was seen as a valuable way to protect kaimoana and give back to Tangaroa. 2709
Increased recreational and tourism opportunities
Studies of the impacts of marine reserves in New Zealand have shown a range of tourism and recreation benefits. For example, the establishment of the Tonga Island marine reserve adjacent to the Abel Tasman National Park, increased the recreational value of the area and, in turn, attracted greater numbers of visitors. In response, new accommodation enterprises have established, and there are growing numbers of water taxi operators. There has also been a significant growth in the number of kayak companies, from the two operating prior to the establishment of the marine reserve, to at least 13 currently.
Similar benefits have been experienced from the Cape Rodney - Okakari Point marine reserve. An economic impact analysis undertaken in 2008 identified an estimated 375,000 annual visits to the reserve and the contribution of $18.6 million a year into the local economy. This was compared to the cost to the Department of Conservation of managing the reserve of around $70,000 per year. 2712
Education and science
Marine reserves provide the opportunity for scientists to study marine communities which are largely intact, and which are not directly disturbed by fishing activity. For example, science undertaken in the Cape Rodney - Okakari Point marine reserve has made a major contribution to our understanding of rocky reef systems in New Zealand.
Scientsts are able to observe unharvested populations of fish in marine reserves. This is important to enable the development of understanding about the natural behaviours and population dynamics of fish species. In addition, reserves enable scientists to carry out longitudinal studies on individuals, which are not possible where fishing takes place, as the individual studied will likely be lost to harvesting during the experiment.
Educational facilities often co-locate with marine reserves, as the reserves provide an excellent place for students and members of the public to observe marine life. For example, the Goat Island Marine Discovery Centre has been located near the marine reserve at Leigh and the Sir Peter Blake Marine Education and Recreation Centre is located adjacent to the Long Bay-Ōkura Marine Reserve.
Re Batemans Bay, Australia - Eadie L and C Hoisington, 2011, 41; A recent study of 11 marine protected areas in rocky zones around Australia showed around 10 times as many large fish in sanctuary zones as fished zones; Edgar G and R Stuart Smith, 2009
Langlois T and W Ballantine, 2005, 1766-1767; Babcock R C et al, 1999,132
Walker B and D Salt, 2006
See e.g. National Oceanic and Atmospheric Administration, 2005
Natural England and the Joint Nature Conservation Committee, 2010
Willis T J, 2013
Simon Thrush, pers comm
Rowley R J, 1992, 8-10
Rowley R J, 1992, 6-7
Smith A N H et al, 2014,211
Roberts C, 2012
Harrison H B, 2012, 1024
Le Port A, J C Montgomery and A E Croucher, In Press, ‘Biophysical modeling of a snapper Pagrus auratus larval dispersal from a temperate MPA’, Marine Ecology Progress Series
Taylor N and B Buckenham, 2003
Hunt L, 2008, 2
Jones G P, 2013
Willis T J, 2013
Last updated at 2:11PM on February 25, 2015