Ecological effectiveness of MPAs
- Variable relationship:
This theory is based on research assessing the ecological effectiveness of marine protected areas (MPAs). Most recently, a meta-analysis paper outlined five key features that contributed to the ecological effectiveness of MPAs. This text from the abstract of the Edgar et al 2014 paper summarizes the relationship: "Here we show that the conservation benefits of 87 MPAs investigated worldwide increase exponentially with the accumulation of five key features: no take, well enforced, old (>10 years), large (>100km2), and isolated by deep water or sand."
- Project
- SESMAD
- Sector(s)
- Marine protected areas
- Scientific Field
- Component Type(s)
- Status
- Public
Variables
| Variable | Role | Role Explanation | Value |
|---|---|---|---|
| Governance system spatial extent | Proximate independent variable | Large (>100km2) MPAs increase ecological benefits. | >100km2 |
| External sanctions | Proximate independent variable | "Efficient enforcement" (the wording used by Edgar et al.) contributed to increases in fish biomass within MPAs. | Yes |
| External monitoring | Proximate independent variable | "Efficient enforcement" (the wording used by Edgar et al.) contributed to increases in fish biomass within MPAs. | Yes |
| Policy instrument | Proximate independent variable | This theory describes marine protected areas | Protected area |
| PA IUCN strict zones | Proximate independent variable | No-take areas were found to be more effective than partially closed areas. | 100% |
| Governance system age | Proximate independent variable | Older MPAs (>10 years) are hypothesize to be more effective. | > 10 years |
| MPA internal natural boundaries | Proximate independent variable | The paper states: "Isolation, a categorical factor that distinguished MPAs with reef habitat surrounded by deep (.25m) water or large expanses of sand from MPAs with shallow reef habitat extending to fished areas, seemed to exert a stronger influence for community level biomass and richness metrics than the other four features." | Yes |
| Transaction costs | Moderating independent variable | Enforcement is much more effective if it is done in a way that keeps transaction costs low. | Low |
| Compliance | Intermediate outcome | Edgar et al. note that compliance may contribute to the isolation effect, in that "isolated MPAs are generally well demarcated for control purposes". | Yes |
| Commons condition trend | Final outcome | This is the outcome variable. MPAs that show improved condition (this outcome) are hypothesized to be influenced by the other variables. Condition is measured in the paper as increases in biomass. | Remained the same or Improved |
Related Theories
| Theory | Relationship | Characterizing Variables |
|---|---|---|
| Enforcement | contains | |
| Local livelihood and protected areas | related | |
| Centralized conservation | related | |
| Critique of fortress conservation | contradictory | |
| CAR principles for conservation area design | related |