The study, whose findings are considered a major advance for fish conservation biology, was conducted by an international team of scientists from Australia, France, and the U.S. using a novel tagging method to track two populations of fish, including the endearing orange, black, and white reef-dwelling clownfish made famous in the movie “Finding Nemo.”
Led by Dr. Geoff Jones and Dr. Glenn Almany of the Australian Research Council Centre of Excellence for Coral Reef Studies at James Cook University, the study took place on coral reefs in a marine protected area in Papua New Guinea. Scientists tested a new method to trace fish from birth to spawning and detect the percentage of fish hatched on one reef that return there to spawn. The techniques used in this study can reveal the extent to which fish populations on separate reefs are isolated breeding populations, or connected by fish movements (known as ‘connectivity’). Such information is critical to effective management of reef fish populations.
Following two fish species, the clownfish (Amphiprion percula) and the vagabond butterflyfish (Chaetodon vagabundus), the scientists found that young of both species made it back to their home reef about 60 percent of the time⎯a surprising result for fish larvae that had dispersed from a small reef habitat into a large area. The researchers tagged fish at the reef surrounding a small island, Kimbe Island, within a recently-designated Marine Protected Area in Kimbe Bay, Papua New Guinea.
“If we understand how fish larvae disperse, it will enable better design of marine protected areas, and this will help in the rebuilding of threatened fish populations,” said Almany, lead author on the Science article. Other members of the team were Michael Berumen of the University of Arkansas, Woods Hole Oceanographic Institution (WHOI) biologist Simon Thorrold, and Serge Planes of the Universite de Perpignan.
The study’s results highlight three notable achievements. This is the first time scientists have successfully used a new internal tagging method in the field, as well as in the lab. It is the first larval tagging study of a pelagic (open water-swimming) spawning fish. It is also the first comparison between two fish species with different reproductive strategies and dispersal patterns.
The tagging method the team employed was developed by Simon Thorrold at WHOI. The process involves injecting minute quantities of harmless stable barium isotopes into breeding female fish of both species. “The isotopes are passed to the offspring and incorporated into the ear bones - or otoliths - of the developing embryos,” said Thorrold, “thereby labeling the hatchlings at birth with the isotopes as permanent traceable tags.”
Two months after injecting females, the scientists returned and captured newly settled fish at the same reef to determine how many had returned to their home reef and how many had migrated from other nearby reefs. The percentage of fish whose otoliths were labeled with the rare barium isotope was identified at WHOI through a technique known as laser ablation inductively coupled plasma mass spectrometry (ICP-MS).
The two species have different reproductive styles. Butterflyfish release eggs and sperm into the water, and the larvae drift and swim freely for more than a month before finding a home reef. In contrast, clownfish spawn eggs that are attached to the reef for a week before the larvae hatch and disperse in oceanic waters for 10-14 days. The larval clownfish must then find a reef, and a suitable anemone, that will be home for the remainder of its life. Currents inevitably carry both species away from the parental reef, because larval fish cannot swim well, but this study confirms that the majority of both species appear to find their way home after completing the oceanic larval phase.
Reef fish conservation programs utilizing marine protected areas are based on assumptions about how many fish migrate in from other areas and how many return to home areas to spawn. At a time of increasing pressures on coral reef ecosystems, this study provides an important piece for planning the optimum size of coral reef protected areas and breeding populations.
“Just as importantly,” said Almany of their results, “40 percent of the juveniles came from other reefs that are at least ten kilometers (five miles) away, which indicates significant exchange between populations separated by open sea. This shows how marine protected areas can contribute to maintaining fish populations outside no-fishing zones.”
The successful test of this method in the field offers scientists and managers a powerful new way to evaluate the effectiveness of management models and practices based on direct information. Thorrold is continuing this work, using the maternal labeling technique to evaluate the degree of connectivity in other fish populations, including endangered Nassau grouper in the Caribbean.
This work was funded in part by the National Science Foundation.
Media Relations Office | EurekAlert!
Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society
Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences