Underwater cameras reveal biodiversity hotspot in tropical marine park
Researchers from The University of Western Australia have found an area of tropical ocean protected under law is a hotspot for iconic marine life but does not provide enough defence from human activities.
While the Oceanic Shoals Marine Park was found to host an abundance of marine wildlife, the study, published in Frontiers in Marine Science, found the zoning classifications of the park permitted activities that were not compatible with the conservation of these species.
The survey of marine life in one of the northernmost Commonwealth Marine Parks examined how species interacted with the area's unique habitat features, including banks and pinnacles that attracted groups of sharks, turtles and large fish.
Using a combination of sampling techniques, including underwater videography, the team from UWA's Marine Futures Lab documented 32 species from 370 hours of video footage.
These ranged from tiny baitfish to ocean top predators such as killer whales, but also included numerous sharks, manta rays, dolphins, turtles, seabirds and sea snakes.
The data was then used to understand how animals were distributed within the park, particularly relative to prominent habitat features such as banks and pinnacles.
The number of large vertebrates increased closer to banks and some communities of fish and sharks found on or around the banks also appeared to differ from those found elsewhere. This confirms that banks are key ecological features of regional importance for marine wildlife.
All cetaceans sighted were in groups that contained young individuals, suggesting the marine park may be of importance in the early life stages of these species.
Lead author Dr. Phil Bouchet said while the declaration of the Marine Park appeared to be a successful example of proactive ocean management, the vast majority of the park remained open to many human activities, including various forms of recreational and commercial fishing.
"All the banks that have been mapped to date fall into multiple use zones, raising concerns regarding the adequacy of protection provided by the park zoning," Dr. Bouchet said.
Co-author Jessica Meeuwig, Director of the Marine Futures Lab at UWA, said the area was clearly a hotspot for marine wildlife yet only 4.6 percent of the park was fully protected from exploitation, namely fishing, mining and oil and gas operations.
"While the aim of the study was to document the marine wildlife found in the region, the data shows a large abundance and diversity of animals near these banks and shoals," Professor Meeuwig said.
"Fishing activities, such as pelagic longline fishing and purse-seining are allowed in 95 percent of the park, despite marine wildlife such as dolphins and sharks being particularly vulnerable to these fishing gears.
"This information provides a crucial baseline for park monitoring and management however, the level of protection falls well short of agreed international targets. Park management should be strengthened to protect this northern jewel."
More information: Submerged Carbonate Banks Aggregate Pelagic Megafauna in Offshore Tropical Australia Front. Mar. Sci., 30 June 2020. doi.org/10.3389/fmars.2020.00530
Provided by University of Western Australia