Connectivity of island ecosystems from a management and ecological perspective
Keywords: plastic pollution
marine management
Islands
Ecosystem management
island ecosystem
Coral Connectivity

In total, two-thirds of the world’s countries are, or include, islands or archipelagos, directly supporting 10% of the world’s population. These islands also support around 20% of global biodiversity but are where 61% of all known extinctions have occurred. Despite their isolation, islands can exhibit high levels of ecological connectivity, or host similar, but genetically distinct, groups of species. The similarity between island ecosystems and the threats they face provides an opportunity to achieve more effective management through management connectivity, for example by sharing lessons learned, pooling dataset and working together to manage threats. Often, however, this management connectivity is lacking. This thesis aims to better understand and enhance the level of management connectivity, and increase management effectiveness of island ecosystems by: (1) exploring current barriers to island ecosystem management; and (2) generating information addressing two threats that are common to island ecosystems in the Seychelles archipelago and elsewhere.
I found a raft of barriers which prevent practitioners from meeting their conservation and management goals, most of which existed at organization level (55%), followed by national (24%) and site/project level (21%). We found that the three most common barriers preventing practitioners from achieving more effective management are: insufficient staff capacity; difficulties turning data into useful information for management (including lack of data analysis capacity and time to analyse); and lack of a research strategy. In addition, numerous barriers to collaboration hinder management connectivity between relevant actors. However, these more common barriers are not the most important in forming respondents’ perceptions about management effectiveness. Instead, their opinion of national level management effectiveness was mostly associated with their perception of governance issues, the presence/absence of research and management strategies and their experience of collaboration outcomes.
To inform management of plastic pollution in the Seychelles I estimate that to remove 1 tonne of litter costs USD8,900 and that to clean up the ca 500 tonnes on Aldabra will cost USD4.68 million and require 18,000 person-hours of labour. Given that this is one island and that plastic pollution is continuously arriving into island ecosystems in the Seychelles, a more coordinated approach to this issue is required in additional to a great deal of funding. To inform management of the coral reef system in Seychelles I have mapped genetic connectivity across the inner and outer islands of Seychelles, showing the first evidence of gene flow between reefs, especially between Aldabra and the Mahé area. With this new evidence of the importance of the outer islands for regional reef persistence in the face of climate change I recommend management actions to increase reef resilience are targeted at Aldabra, being the largest reef system in the outer islands.
Increasing management connectivity has the potential to greatly enhance overall management effectiveness at local and national levels, whether by understanding the impacts and costs involved in marine plastic pollution to generate funding and guide actions, or identifying important larval source reefs to inform management of coral reefs. But to achieve sustained management connectivity requires greater local collaboration, greater transparency in success/failure, higher levels of data pooling, stronger alignment of local-level efforts with national targets and overall greater sharing of knowledge and information between practitioners, government, and scientists. All of these can be achieved through targeted actions at site, organization and national level.