Connectivity

 

AIMS is investigating the connectivity of reef systems on the east and west coast by studying the movement of coral larvae, jellyfish and fish among reef and estuary populations.

Connectivity is the process by which local marine populations recruit larvae from distant sources via the currents that connect one part of the ocean with another. It is essential for maintaining the genetic diversity and resilience of these populations.

Sink, or downstream, reefs maintain their genetic diversity by importing coral larvae via these ocean currents from source, or upstream, reefs that have diverse populations of adult corals. This input of new genetic material is important for the resilience and recovery of coral reefs in the face of environmental change.

On the east coast, AIMS oceanographers are investigating these hydrodynamic pathways using satellite-tracked drifting buoys, in situ observations of ocean currents and computer simulations.

We are also using population genetics approaches to assess the movement of reef-related organisms and to identify potential migrants that have settled on a reef over the past few generations.

On the west coast, AIMS researchers are focusing on the oceanic reef systems near the edge of Australia’s north-west continental shelf.

Unlike continuous reef systems such as the Great Barrier Reef, these north-west systems are extremely isolated, with hundreds of kilometres between the reefs and the coastline, and between each other.

Understanding connectivity in this region has important management implications for these reefs. Do local populations maintain the corals and fish or do a sufficient number of larvae survive the long journey from another reef to aid recovery from disturbances?

AIMS has used satellite-tracked drifters and ocean models, combined with genetic analyses, to reveal that these oceanic reef systems and fish are largely isolated when maintaining populations and recovering from disturbances.

Without an external supply of recruits, the coral and fish will take longer to recover from severe, widespread disturbances. Subsequent reductions in genetic diversity may possibly reduce the ability of populations to absorb future climatic extremes.

We have worked with Marine Protected Area planners, managers and scientists to help integrate this connectivity knowledge into effective management guidelines and policy in north-west Australia.

However, recent AIMS research has also shown that the benefits of their isolation from human pressures can outweigh the costs of their limited connectivity.

What remains to be determined is the degree of connectivity within each of these reef systems, and locations that are an important source of recruits for other populations of coral and fish.