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Ocean maps show human impacts on global scale


March 04, 2008

The ocean has inspired men and women who looked out over its wide vistas to the horizon and dreamed – or schemed. Its depths have provided food, inspired empires, and belched forth a wealth of resources and opportunities.

Writ on waves, wash and spray is also much of human history, from the cod-fueled voyaging by the Vikings and Portuguese to storm-laden disasters where Armadas sailed and faltered, from “sea to shining sea.”

But is the vision of endless oceanic bounty and ecosystem diversity that launched a thousand of ships, like Homer’s Helen of Troy, rapidly becoming part of a legendary past?

Many experts believe so.

“You go to a forest and immediately notice when it is clear-cut,” says Caterina D’Agrosa, a postdoctoral fellow in ASU’s School of Life Sciences. “However, when you go to the beach, the ocean almost always looks the same, regardless of whether there are fish in it or not.

This, I think, is one of the largest problems with marine conservation: our perception.”

D’Agrosa, a marine ecosystems scientist, is one of 19 researchers whose study, published in the journal Science Feb. 15, challenges historic views of marine systems and humans’ impact through fishing, introduction of invasive species and pollution.

As with the research that fueled Al Gore’s movie, “An Inconvenient Truth,” that set the world to thinking, this study considers for the first time the sum of 17 human-driven impacts on a score of marine ecosystems, including coral reefs, estuaries and pelagic waters.

Led by Ben Halpern of the National Center for Ecological Analysis and Synthesis (NCEAS) at the University of California-Santa Barbara, the authors tell us that “no area of the ocean is unaffected, and more than 41 percent experiences high levels of human influence.”

The most heavily affected oceans include the North Sea, China Seas, Caribbean, eastern North American seaboard, Mediterranean, Red Sea, Persian Gulf, Bering Sea and portions of the western Pacific. Still, a few regions remain largely untouched.

“This project allows us to finally start to see the big picture of how humans are affecting the oceans,” Halpern says, adding that the results also show “that the big picture looks much worse than I imagine most people expected.”

Moreover, this study is considered by its authors to be conservative. According to Halpern and his colleagues, many human influences could not be incorporated in the study, including effects from hypoxic “dead” zones, coastal engineering, aquaculture, disease, tourism or recreational fishing, changes in sedimentation and freshwater input, illegal or unregulated fishing, or past events.

Regardless, the researcher’s global map is a tool to guide policy-makers, conservation managers and provide “critical information for evaluating where certain activities can continue with little effect on the oceans, and where other activities might need to be stopped or moved to less sensitive areas.”

“I think the biggest thing is that we hope to change with this Science paper is the perception of humans as to the status of the oceans,” D’Agrosa says. “Hopefully, this change in perception will lead to action.”

D’Agrosa’s work has been largely centered in the Gulf of California in Mexico. As a graduate student with Instituto Tecnológico y de Estudios Superiores de Monterrey (ITESM) in Guaymas, Mexico, she looked at the interactions between fishing practices and the endangered vaquita.

As the smallest marine porpoise in the world, the vaquita is found only in the upper Gulf of California. Since then, her goal has been to develop understanding about human impacts, how to establish more sensitive management practices and ways to balance ecosystem and human needs.

With funding from the Nature Conservancy and World Wildlife Fund, D’Agrosa and a host of U.S. and Mexican partners’ project includes the biological prioritization of a network of 54 conservation areas throughout the Gulf, as well as developing understanding about their connectivity to one another – be that at the level of plankton or whales – and to human activities in the region. The areas were selected with the help of Comunidad y Biodiversidad (COBI), a non-governmental organization in Mexico.

“The purpose of this project is to give the Nature Conservancy and the World Wildlife Fund some guidelines for where to allocate their time, money, people and resources, and to help them prioritize and maximize their efforts,” D’Agrosa says. “And to help us understand how the Gulf works so that we can best protect its productivity and biodiversity.”

D’Agrosa’s piece of the Gulf project involves examination of the key species and ecosystems, and the species connectivity in those 54 areas.

Figuring out “how the Gulf works” also includes D’Agrosa considering potential threats and their impacts to the entire region. For example, one threat that arises from pollution flowing from the mouth of the Yaqui Valley River can have effects across the Gulf, in the form of algal blooms, nearly 850 kilometers to the south in marine-protected areas in Loreto Bay Marine Park.

Other researchers, such as those with the University of Arizona’s PANGAS project, focus instead on fishers, their habits and needs in the Gulf. Still others, such as master’s degree student Zach Hughes with the ASU School of Sustainability, look at economic aspects.

The desired outcome is to produce a fully integrated study that considers as a whole, all human and ecosystem impacts in the Gulf, and their inter-relationships, in keeping with the perspective laid out in the Science paper’s study.

“The time of considering single impacts of human on oceans is over,” D’Agrosa says. “By considering the sum of all the impacts together, we can offer practical and realistic guidelines for policy-makers and managers at the local level, in conservation areas, parks and marine protected areas, as well as at a national and international level.”

In 2007, D’Agrosa, ASU professor Leah Gerber and others compiled a handbook to assist decision-makers, titled “Navigating Uncertain Seas: Adaptive Monitoring and Management of Marine Protected Areas,” which was funded by ASU and the Scripps Institute of Oceanography, with support from private foundations, in conjunction with the Department of the Environment of Mexico (SEMARNAT).

Their handbook offers practical guidance for adaptive monitoring, assessment, and management of marine protected areas that can be applied worldwide, through a “real world” lens.

The handbook arose as a result of Gerber and his colleagues’ research in, and review of, the lessons learned at Loreto Bay Marine Park, a “biologically diverse area subject to intense fishing pressures,” and an ideal laboratory in which to examine marine management and its impact on local communities.

Of their work, Gerber notes, “I think one of the important components of trying to balance priorities between human communities and conservation is recognizing that the world is not what it once was, and that we need to be strategic in how we preserve remaining biodiversity while allowing sustainable human communities.”

So how can communities such as Phoenix, which is far from the sea, contribute to the preservation of ocean systems?

“Consider how you vote, give money to good environmental agencies and tread lightly,” D’Agrosa says. “Even though we live in a desert, we are upstream and affect watersheds, regional economies, and coastal development.”

For information on seafood visit the Web sites http://seafood.audubon.org/seafood_wallet.pdf, www.environmentaldefense.org/page.cfm?tagID=1521, www.sierraclub.org/sustainable_consumption/food_factsheet.asp and www.nrdc.org/health/effects/mercury/walletcard.pdf.