New publication: A typology for reef passages

In spring 2021 I joined the SOCPacific-project as an intern working mostly on a literature review on the socio-ecological importance of reef passages (especially for remote island states in the south-west pacific). What I found confirmed my intuition as a marine biologist but most of all revealed a large gap in our understanding and recognition of these unique and particular spaces.

Although there seems to be no standard definition for reef passages, they can generally be understood as a channel/gap in the reef that connects the outer ocean with the shallower, landward side of the reef.

Going back in human history, such passages arguably played a crucial role regarding human settlement, especially across remote island states that are surrounded by reefs. Knowing the exact position of safe passages was outermost important to the native inhabitants and also provided access to rich fishing grounds. Up to today many passages hold names in the native languages and are of spiritual significance. If you think about it, for a very long time these channels were the only transit zones that allowed exchange with the outer world. Everything - from goods, to humans and services - had to pass through these zones.

On an ecological level, very little research directly addressed the importance of such passages, although it is evident that these systems are involved and support many crucial ecological processes. They might be seen as the main arteries for the energy supply of adjacent waters. Thus, they directly enhance ecosystem health and functionality. For centuries, local fishermen have sought out certain passages at certain times of the year for fishing. This knowledge has helped scientists to discover so-called "fish-spawning-aggregations" - events where sometimes hundreds or thousands of fish gather to reproduce. The in- and out-going currents make these areas the perfect spots for larval dispersal. Besides reproduction, many species seek out channels in the reef in search of food. The currents often transport food sources for herbivorous fishes which are then followed by larger, predatory species.

Given their significance and benefits for adjacent ecosystems, some scientists argue that the protection of these areas will have an umbrella-effect in terms of maintaining healthy ecosystem functions and services. They can arguably be seen as hotspots of connectivity, productivity and biodiversity and also provide multiple invaluable benefits to the islands and their inhabitants. However, so far they received very little attention regarding marine spatial planning and conservation management.

The research we published is a first step towards the recognition of these unique areas and their future implementation in marine spatial planning. By helping to identify priority areas for protection we hope it will accelerate the progress of marine conservation in the study area and beyond.