Oct 30, 2015 07:25 PM
Marine reserves will need stepping stones to help fish disperse between them
RELEASE: A massive field effort on the Belizean Barrier Reef has revealed for the first time that the offspring of at least one coral reef fish, a neon goby, do not disperse far from their parents. The results indicate that if marine protected areas aim to conserve such fishes, and biodiversity more broadly, then they must be spaced closely enough to allow larvae to disperse successfully between them.
A growing body of scientific research has demonstrated that marine protected areas, particularly no-take marine reserves that exclude extractive activities like fishing, can increase biodiversity and sustain fisheries within the reserves, often with spillover benefits in surrounding areas. But despite the decline of coral reefs and fisheries worldwide, only 3.5 percent of the ocean is protected and only 1.6 percent of it is fully protected. Moreover, for reserves to conserve marine biodiversity most effectively, they must be embedded in networks that are connected such that marine life from one reserve can repopulate other reserves.
"Before our study, we didn't have a deep, quantitative understanding of how far fish larvae do and do not disperse from their parents," says study co-author Peter Buston of Boston University. "If we're going to design effective networks of marine reserves, we need to know how far baby fish can and cannot travel. Our study suggests that for fishes like the neon gobies, protected areas may need to be close together."
Last week, the Pacific Island nation of Palau was the most recent nation to announce the designation of a large-scale marine reserve in its waters. Other nations announcing large marine reserves in the past year include New Zealand and Chile. In the U.S., in September 2014, President Obama expanded the impressive Pacific Remote Islands National Marine Monument to more than 490,000 square miles.
Such large reserves can provide habitat for a wide variety of species. But most marine reserves remain much smaller, and lead author Cassidy D'Aloia, now at the University of Toronto, notes that marine life still needs to travel among reserves. "If reserves are connected, then if a catastrophe occurs in one reserve, then that population can potentially be rescued by larvae from another reserve."
For their study, D'Aloia and her co-authors collected thousands of tissue samples from neon goby parents and offspring along a 41 km (about 25 miles) length of the Belizean Barrier Reef to determine how far those offspring traveled. They found that larvae typically dispersed no more than 1.7 kilometers (about one mile) from their parents and in no cases dispersed more than 16.4 km (about 10 miles). Although the study looked at only one species, gobies are the most diverse family of ocean fishes.
"Our research shows that some larval fish are not traveling very long distances, and that pattern is likely stable over long-periods of time. This result suggests that large marine reserves will need stepping stone reserves to help some fishes disperse between them," says Buston.
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100-year-old mystery solved: Adult eel observed for the first time in the Sargasso Sea
RELEASE: After more than a century of speculation, researchers have finally proved that American eels really do migrate to the Sargasso Sea to reproduce. A team supervised by Professor Julian Dodson of Université Laval and Martin Castonguay of Fisheries and Oceans Canada reports having established the migratory route of this species by tracking 28 eels fitted with satellite transmitters. One of these fish reached the northern boundary of the Sargasso Sea, the presumed reproduction site for the species, after a 2,400 km journey. Details are published in the latest edition of Nature Communications.
The discovery puts an end to more than a hundred years of conjecture regarding the migratory route and location of the only American eel reproduction site. "Eel larvae have been observed in the Sargasso Sea since 1904, suggesting that the species reproduced in this area, but no adult eels had ever been observed in this part of the Atlantic Ocean," explained Professor Dodson of the Faculty of Science and Engineering at Université Laval.
The many expeditions aimed at catching eels in their mysterious gathering site have all failed, but the recent development of sophisticated satellite transmitters opened up new opportunities for researchers. Julian Dodson and his team affixed these transmitters to 22 eels captured in Nova Scotia and 16 from the St. Lawrence Estuary. In the ensuing weeks, 28 of these transmitters resurfaced in different areas of the Atlantic and transmitted the data they had recorded.
Analysis of the data revealed that all the eels adopted similar migratory paths and patterns. Near the coastline they appear to use the salinity level and temperature to find the high seas. A single eel provided data for the ocean segment of the migration. Its transmitter showed that it turned due south upon reaching the edge of the continental shelf, and headed straight to the Sargasso Sea. In 45 days, this eel captured in the province of Quebec covered 2400 km. "This points to the existence of a navigation mechanism probably based on magnetic field detection," asserted Professor Dodson.
Julian Dodson remains cautious about drawing premature conclusions from some thirty eels, only one of which travelled the full migratory route. "Our data nonetheless shows that the eels don't follow the coastline the whole way, they can cover the route in just weeks, and they do go to the Sargasso Sea. We knew that millions of American eels migrated to reproduce, but no one had yet observed adults in the open ocean or the Sargasso Sea. For a scientist this was a fascinating mystery."
RELEASE: A massive field effort on the Belizean Barrier Reef has revealed for the first time that the offspring of at least one coral reef fish, a neon goby, do not disperse far from their parents. The results indicate that if marine protected areas aim to conserve such fishes, and biodiversity more broadly, then they must be spaced closely enough to allow larvae to disperse successfully between them.
A growing body of scientific research has demonstrated that marine protected areas, particularly no-take marine reserves that exclude extractive activities like fishing, can increase biodiversity and sustain fisheries within the reserves, often with spillover benefits in surrounding areas. But despite the decline of coral reefs and fisheries worldwide, only 3.5 percent of the ocean is protected and only 1.6 percent of it is fully protected. Moreover, for reserves to conserve marine biodiversity most effectively, they must be embedded in networks that are connected such that marine life from one reserve can repopulate other reserves.
"Before our study, we didn't have a deep, quantitative understanding of how far fish larvae do and do not disperse from their parents," says study co-author Peter Buston of Boston University. "If we're going to design effective networks of marine reserves, we need to know how far baby fish can and cannot travel. Our study suggests that for fishes like the neon gobies, protected areas may need to be close together."
Last week, the Pacific Island nation of Palau was the most recent nation to announce the designation of a large-scale marine reserve in its waters. Other nations announcing large marine reserves in the past year include New Zealand and Chile. In the U.S., in September 2014, President Obama expanded the impressive Pacific Remote Islands National Marine Monument to more than 490,000 square miles.
Such large reserves can provide habitat for a wide variety of species. But most marine reserves remain much smaller, and lead author Cassidy D'Aloia, now at the University of Toronto, notes that marine life still needs to travel among reserves. "If reserves are connected, then if a catastrophe occurs in one reserve, then that population can potentially be rescued by larvae from another reserve."
For their study, D'Aloia and her co-authors collected thousands of tissue samples from neon goby parents and offspring along a 41 km (about 25 miles) length of the Belizean Barrier Reef to determine how far those offspring traveled. They found that larvae typically dispersed no more than 1.7 kilometers (about one mile) from their parents and in no cases dispersed more than 16.4 km (about 10 miles). Although the study looked at only one species, gobies are the most diverse family of ocean fishes.
"Our research shows that some larval fish are not traveling very long distances, and that pattern is likely stable over long-periods of time. This result suggests that large marine reserves will need stepping stone reserves to help some fishes disperse between them," says Buston.
- - - - - - - -
100-year-old mystery solved: Adult eel observed for the first time in the Sargasso Sea
RELEASE: After more than a century of speculation, researchers have finally proved that American eels really do migrate to the Sargasso Sea to reproduce. A team supervised by Professor Julian Dodson of Université Laval and Martin Castonguay of Fisheries and Oceans Canada reports having established the migratory route of this species by tracking 28 eels fitted with satellite transmitters. One of these fish reached the northern boundary of the Sargasso Sea, the presumed reproduction site for the species, after a 2,400 km journey. Details are published in the latest edition of Nature Communications.
The discovery puts an end to more than a hundred years of conjecture regarding the migratory route and location of the only American eel reproduction site. "Eel larvae have been observed in the Sargasso Sea since 1904, suggesting that the species reproduced in this area, but no adult eels had ever been observed in this part of the Atlantic Ocean," explained Professor Dodson of the Faculty of Science and Engineering at Université Laval.
The many expeditions aimed at catching eels in their mysterious gathering site have all failed, but the recent development of sophisticated satellite transmitters opened up new opportunities for researchers. Julian Dodson and his team affixed these transmitters to 22 eels captured in Nova Scotia and 16 from the St. Lawrence Estuary. In the ensuing weeks, 28 of these transmitters resurfaced in different areas of the Atlantic and transmitted the data they had recorded.
Analysis of the data revealed that all the eels adopted similar migratory paths and patterns. Near the coastline they appear to use the salinity level and temperature to find the high seas. A single eel provided data for the ocean segment of the migration. Its transmitter showed that it turned due south upon reaching the edge of the continental shelf, and headed straight to the Sargasso Sea. In 45 days, this eel captured in the province of Quebec covered 2400 km. "This points to the existence of a navigation mechanism probably based on magnetic field detection," asserted Professor Dodson.
Julian Dodson remains cautious about drawing premature conclusions from some thirty eels, only one of which travelled the full migratory route. "Our data nonetheless shows that the eels don't follow the coastline the whole way, they can cover the route in just weeks, and they do go to the Sargasso Sea. We knew that millions of American eels migrated to reproduce, but no one had yet observed adults in the open ocean or the Sargasso Sea. For a scientist this was a fascinating mystery."