"region" that group MPAs are not always consistently employed."System" is more often used to refer to an individual MPA, whereas "region" is defined by the World Conservation Monitoring Centre as: A collection of individual MPAs operating cooperatively, at various spatial scales and with a range of protection levels that are designed to meet objectives that a single reserve cannot achieve. At the 2004 Convention on Biological Diversity, the agency agreed to use "network" on a global level, while adopting system for national and regional levels. The network is a mechanism to establish regional and local systems, but carries no authority or mandate, leaving all activity within the "system". No take zones (NTZs), are areas designated in a number of the world's MPAs, where all forms of exploitation are prohibited and severely limits human activities. These no take zones can cover an entire MPA, or specific portions. For example, the Papahānaumokuākea Marine National Monument, the world's largest MPA (and largest protected area of any type, land or sea), is a 100% no take zone. Related terms include; specially protected area (SPA), Special Area of Conservation (SAC), the United Kingdom's marine conservation zones (MCZs), or area of special conservation (ASC) etc. which each provide specific restrictions. Stressors Stressors that affect oceans include the impact of extractive industries, marine pollution, and changes to the ocean's chemistry (ocean acidification) resulting from elevated carbon dioxide levels, due to our greenhouse gas emissions (see also effects of climate change on oceans). MPAs have been cited as the ocean's single greatest hope for increasing the resilience of the marine environment to such stressors. Well-designed and managed MPAs developed with input and support from interested stakeholders can conserve biodiversity and protect and restore fisheries. Economics MPAs can help sustain local economies by supporting fisheries and tourism. For example, Apo Island in the Philippines made protected one quarter of their reef, allowing fish to recover, jumpstarting their economy. This was shown in the film, Resources at Risk: Philippine Coral Reef. A 2016 report by the Center for Development and Strategy found that programs like the United States National Marine Sanctuary system can develop considerable economic benefits for communities through Public–private partnerships. They can be self-financed through a surrounding "conservation finance area" in which a limited number licenses are granted to benefit from the spillover of the marine protected area. Management Typical MPAs restrict fishing, oil and gas mining and/or