*Like the rainforest which takes its name, the Amazon is the largest and most biodiverse river on the planet. The river and its tributaries are a critical thoroughfare for an area the size of the continental United States and function as a key source of food and livelihoods for millions of people. Yet despite its vastness and importance, the mighty Amazon is looking increasingly vulnerable due to human activities.

*Few people understand more about the Amazon’s ecology and the wider role it plays across the South American continent than Michael Goulding, an aquatic ecologist at the Wildlife Conservation Society (WCS) who has worked in the region since the 1970s studying issues ranging from the impact of hydroelectric dams to the epic migration of goliath catfishes. Goulding has written and co-authored some of the most definitive books and papers on the river, its resident species, and its ecological function.

*In recognition of his lifetime of advancing conservation efforts in the Amazon, the Field Museum today honored Goulding with the Parker/Gentry Award. The Award — named after ornithologist Theodore A. Parker III and botanist Alwyn Gentry who were killed in a plane crash during an aerial survey of an Ecuadorian cloud forest in 1993 — is given each year to "an outstanding individual, team or organization in the field of conservation biology whose efforts have had a significant impact on preserving the world’s natural heritage and whose actions and approach can serve as a model to others."

Like the rainforest which takes its name, the Amazon is the largest and most biodiverse river on the planet: the Amazon carries more than five times the volume of world’s second largest river — the Congo — and its basin is home to at least 3,000 species of fish. The river and its tributaries are a critical thoroughfare for an area the size of the continental United States and function as a key source of food and livelihoods for millions of people.

Yet despite its vastness and importance, the Amazon faces a deluge of threats: a dam-building spree across the basin is disrupting fish migration and nutrient cycling, large-scale deforestation is destroying habitats and increasing sedimentation, pollution from mining and agribusiness is affecting aquatic ecosystems, overfishing is diminishing the capacity of some species to recover, and drought and flood cycles are becoming more pronounced. The effects of climate change could exacerbate some of these impacts by increasing temperatures, the severity of droughts, and the incidence of fires. The mighty Amazon is looking increasingly vulnerable.

Few people understand more about the Amazon’s ecology and the wider role it plays across the South American continent than Michael Goulding, an aquatic ecologist at the Wildlife Conservation Society (WCS) who has worked in the region since the 1970s studying issues ranging from the impact of hydroelectric dams to the epic migration of goliath catfishes. Goulding has written and co-authored some of the most definitive books and papers on the river, its resident species, and its ecological function.

In recognition of his lifetime of advancing conservation efforts in the Amazon, the Field Museum will today honor Goulding with the Parker/Gentry Award. The Award — named after ornithologist Theodore A. Parker III and botanist Alwyn Gentry who were killed in a plane crash during an aerial survey of an Ecuadorian cloud forest in 1993 — is given each year to "an outstanding individual, team or organization in the field of conservation biology whose efforts have had a significant impact on preserving the world’s natural heritage and whose actions and approach can serve as a model to others."

According to the Field Museum, the Award "is designed to highlight work that could benefit from wider publicity and fuller dissemination of scientific results." The Museum said it selected Goulding as "one of the world’s leading experts on Amazonian rivers and their biodiversity."

"He is helping change our largely terrestrial view of conservation to one that puts rivers at the center," said Field in a statement. "He pulls together multiple disciplines and collaborators across the Amazon basin to understand historical patterns, identify current concerns, and make recommendations for the future."

"[Goulding] has been a driving force on a slew of peer-review articles that champion a basin-wide approach to understanding reproduction of Amazonian food fishes, especially long-distance migrants. His efforts have led to new approaches to Amazon conservation, focusing on its aquatic life."

In a September 2020 interview ahead of the prize ceremony, Goulding spoke with Mongabay about his research and the current state of the Amazon.

Mongabay: What led you to pursue your career?

Michael Goulding: I have been interested in Nature and rivers since childhood. In college, I first became interested in geography because of a desire to travel to foreign lands, which soon led to an interest in the tropics, especially those of the New World.

While in college in California, I travelled extensively in Mexico and saw rainforests for the first time. This ignited my interest in rainforest. Along with a desire to study rivers, this led me to start thinking about just where to direct my career, and I soon settled on South America and, shortly after that, on the Amazon as it has the world’s largest rainforests and rivers.

My interest in fish was also since childhood, but learning of the unequalled diversity of Amazon fishes it was an easy zoological choice for the naturalist side of me.

In graduate school at UCLA, I focused on ecosystems, biogeography, conservation, ichthyology, and plant taxonomy to prepare to work in the Amazon. I was extremely lucky to be hired by the National Institute of Amazonian Research (INPA) in Manaus, Brazil while I also finished my Ph.D dissertation. This opportunity was the first conduit to realize my career dreams.

You’ve been working in the Amazon since the 1970s, during which more than 750,000 square kilometers of forest has been cleared across the basin. What are the biggest changes have you seen since the beginning of your career? Both in terms of shifts in the research field and ecological/environmental changes.

At the mega level, deforestation and dams on large rivers are the two major changes since the early 1970s when I made my first trip to the Amazon. Large-scale and artisanal mining and urbanization are the next biggest changes. Taken together, these changes now have synergistic impacts at the ecosystem level. Potential deforestation impacts became apparent relatively early, especially with the construction of the Tran-Amazon Highway in Brazil aimed at opening cattle ranches and settling agriculturalists from Northeastern Brazil to develop the Amazon.

Relatively little attention, however, was given to wetland forest destruction, especially on the floodplains of the lower Amazon River where jute farming and livestock ranching had taken a toll. The exponential increase in new highways and roads since the 1970s resulted in large-scale deforestation across a wide part of the Amazon, and especially south of the Amazon River. The expansion of the soybean frontier in the southeastern basins of the Amazon and agricultural and mining expansion in the Andes also led to serious deforestation and local pollution of westernmost headwaters.

Satellite imagery and GIS software in the last two decades made it possible to track deforestation accurately across the Amazon. The conceptual linkage of the rainforest to the hydrological cycle through the evapotranspiration role of trees greatly strengthened the need for an ecosystem approach to the Amazon. Ironically, however, since about the late 1980s most research and conservation attention focused on relatively small areas without complementary larger scale perspectives to place them in a larger ecological context. River flow impacts increase cumulatively in a downstream direction; thus everyone is downstream in some way. It became apparent that river basin perspectives provide an urgent synergistic view of upland and wetland impacts together at multiple scales across the Amazon if management conservation of the aquatic ecosystem is to be successful.

Since the late 1990s, the Amazon has experienced at least four major droughts. What are the implications of these droughts for aquatic life in the region?

Extreme hydrological events, either droughts or floods, or some combination, affects ecosystem function. For aquatic biodiversity, droughts are often of more concern than extreme floods, and the opposite is often true for human societies along the rivers. Extreme droughts lead to a great reduction of habitat space, especially on floodplains but also in rivers and streams. Increased fish and other biodiversity mortality increases because of limited space, increased predation and overfishing by local and urban fishers. The latter greatly exacerbates the already precarious management of fisheries. Likewise, other aquatic wildlife, such as turtles and the Amazon manatee, become even more vulnerable than fishes.

The long-term effects of large floods on aquatic biodiversity are more difficult to ascertain. It appears that they can increase fish production because of expanded space and a longer period of inundation. With extreme droughts and associated mortality, however, this theoretical advantage of large floods would disappear. Extreme flood levels for three or four years can also lead to die-offs of parts of floodplain shrub and tree communities, as they need an emerged period each year.

While a number of dam projects have been put on hold the past few years, there are still ambitious plans for hydropower expansion across much of the Amazon Basin. What are the potential implications of large-scale dam construction in the basin?

Most focus has been on large dams constructed on the Tocantins, Xingu and Madeira rivers in the eastern half of the Amazon Basin in Brazil. These dams are located on the ancient uplands referred to as the Brazilian Shield, which in the west extends somewhat across the Madeira River where its dams are located. The Brazilian Shield drains four large rivers, and the only one thus far not dammed is the Tapajós, though there are proposals to dam it as well. All four of these tributaries enter the Amazon Basin in its eastern half. To date, large dams affect their individual tributaries more than having a cumulative impact on the Amazon River or its estuary. Since the southeastern sub-basins are also major agricultural and mining frontiers, a synergistic combination of deforestation, dams, pollution and mining affects the rivers. We still do not know where the tipping point is, that is, at what point do x number of dammed major tributaries then begin to affect the ecology of the Amazon River and its estuary.

Unlike the other three Brazilian Shield tributaries, the Madeira has headwaters in the Andes of Bolivia and Peru. The two existing Madeira dams represent the first major basin-wide impact on the Amazon aquatic ecosystem. Although run-the-river dams with relatively low walls, the Madeira dams nevertheless block fish migrations, such as those of goliath catfishes that migrate upstream from the estuary to spawn in or near the Andes. A fish bypass constructed at the Santo Antonio dam near the city of Porto Velho in the state of Rondônia is not functioning as planned, and none exits at the Jirau dam upstream of it. This means that the Madeira dams block some of the most important fish migrations in the Amazon, and this has impacts as far away as the Amazon River estuary, the nurseries for some of the species. Similar to salmon, it appears that at least the dourada (Portuguese) or dorado (Spanish) catfish might practice homing, the biological phenomenon where a species returns to the general region of its birth. This would mean that the Madeira dams would drive a major population of the species to extinction and eliminate perhaps 40% of the spawning grounds of the species.

Thus far, the Andes has few large dams, though governments have identified six major potential hydroelectric dam sites near the outlets from the mountains. Unlike in the Eastern Amazon, the Andean large dams would mostly likely have high walls with deep reservoirs. The Andes are the sediment and nutrient bank for not only for the tributaries that drain them but for the Amazon River as well. Thus, high wall dams could seriously affect the chemistry and alluvial properties of a major part of the Amazon aquatic ecosystem, from more than 4,000 km upstream to the Atlantic. Decreased sediments and nutrients would lead to decreased productivity on the western floodplains and along the Amazon River to its estuary, all of which are important nurseries for fish. Most ecological and social focus is on the Marañón River at the Pongo de Manseriche, a gorge where the largest of the six potential dams is located. It is still unclear whether Peru will move ahead with the Manseriche dam.

A large number of small dams can often have even greater impacts than a single large dam. Small dam construction is exploding across the Amazon from the highlands to the lowlands, but especially in drier areas in the north and south and in the higher parts of the Andes. With predicted drier climates and expanded agriculture and aquaculture, and lack of stream management, small dam construction now presents a major ecological challenge in some parts of the Amazon.

Perhaps a major positive note on dam building in the region is that the Amazon River will remain the only large river in the world without a dam or locks. Although there were futuristic proposals to dam the Amazon River, none is feasible.

A generation ago there was a lot of discussion around the potential for fish farming in the Amazon floodplains to provide a more sustainable source of protein than land-based livestock. Has this materialized? And what are the implications?

Governments subsidized many of the first efforts but the private sector now leads in aquaculture development. Fish farming exists between ecological controversy and dreamland, with a practical center somewhere between.

Two major aspects of aquaculture are relevant to the Amazon, generally categorized as intensive and extensive fish farming. Most fish farming in the Amazon is intensive and uses excavated ponds or dammed streams, with floating cages in the floodplain lakes or in smaller river channels of only minor importance. Most aquaculture is for food fish with minimal production for aquarium and sport fishing species. There have been aquaculture projects aimed at export markets because of higher prices, though to date these have not been particularly successful. The most successful operations target high-priced species now threatened in the wild, thus opening an urban market for aquaculture more than aimed as decreasing overfishing of wild stocks.

An especially important species is the large fruit-and-seed eater called tambaqui in Brazil and often gamitana in Spanish-speaking countries of the Amazon. Overfishing has led to nearly commercial extinction of wild-caught large fish over most of the Amazon. The tambaqui was the most important commercial species captured in the Central Amazon during the 1970s but now is relatively unimportant in fisheries. Aquaculture now produces more tonnage of this species than the maximum wild catches registered decades ago, but this has done little to decrease overexploitation of wild populations. A large wild tambaqui can sell for more than $100, thus there is economic incentive to exploit it despite its rarity. Farm-raised fish contribute relatively little to overall food security since they are too expensive for lower income groups. In short, it seems improbable that aquaculture can substitute wild fisheries or decrease pressure on favored wild species.

Another big question is whether aquaculture could realistically be an alternative to livestock ranching, that is deforestation, for protein production and, if so, just how? Perhaps the main metric is whether quality fish, without subsidies, fetch the same price or cheaper as chicken since poultry is generally less expensive than beef and pork and more accessible to poorer economic classes. Chicken farming is just as intensive if not more so than aquaculture and operates in a similar manner in terms of processed feed for the captive animals. Thus, if the idea is to produce affordable protein for multiple economic classes, then poultry might be a better solution to alleviate fishing pressure on wild fish populations.

Aquaculture beyond any doubt has a role in the Amazon for urban markets. The main controversy is whether overexploited species, such as the tambaqui, would benefit from restocking. Extensive aquaculture involves placing nursery-raised young fish into the wild to replenish overfished populations. There are few experiments to know if this would even be successful in the Amazon and what impacts it might have, such as on genetic diversity of wild populations. Extensive aquaculture already exists to some extent with exotic rainbow trout in the higher Andes, but this has introduced exotic parasites, always a major concern to the health of native species.

Along with your colleagues, you’ve written a number of landmark books and papers on the aquatic ecology of the Amazon Basin. Which of your findings or projects are you most proud of?

My main criterion has always been rather our work was directly relevant to conservation and how does it fit into the big picture. At the most fundamental ecological connectivity level, this meant elucidating how rivers and rainforests are connected. I called this very simply "The Fishes and the Forest" since the two are dependent on each other. Fishes across the Amazon are highly dependent on wetland forests to which they migrate during the floods for food and protection from predators. Likewise, fruit-eating fishes are important seed dispersers for many wetland tree and shrub species.

Another large-scale phenomenon we worked on aimed at dispelling the idea that the Amazon’s second largest tributary, the Rio Negro, a blackwater river, could not support high aquatic biodiversity because of its extreme nutrient poverty, low pH and organic compounds that render it blackish or brownish in color. We were able to demonstrate that there is actually "Rich Life in Poor Water", a concept vitally important not only for conservation of the Rio Negro but also other blackwater rivers in the Amazon.

A third major theme I worked on over decades, along with Ronaldo Barthem of the Goeldi Museum and other colleagues, was long-distance fish migrations from the Amazon River estuary to as far away as the Andean foothills. Demonstrating these migrations, and the scale at which they occur, demonstrated how the Amazon aquatic ecosystem connects biologically from the Andes to the Atlantic in what we termed "The Catfish Connection". This has major implications in terms of infrastructure development impacts, including dams and headwater deforestation that can affect these continental-wide migrations.

Other projects included viewing fisheries at the ecosystem level, the importance of palm swamps, human use of the Amazon River floodplain and helping to develop a new river basin classification for the Amazon that enhances analyzes and spatial views of the aquatic ecosystem in its many facets. All of these works aimed at increasing an understanding of ecosystem scale and its implications for conservation and management planning.

What’s your outlook for the Amazon’s aquatic ecology? And what do you see as the best ways to maintain the health and productivity of the ecosystem?

The main positive that the Amazon has in terms of aquatic ecology conservation is its size, though this also presents the greatest challenge, as there are too few people and funds to analyze the in-water and on-ground impacts of deforestation, dams, mining, increased river traffic, urbanization and other influences at large river basin scales. Other than addressing these challenges through environmental policy, there must also be a scientific and social paradigm shift beyond a propensity to focus only on local areas. A complementary big-picture approach that integrates biological and social data is also required.

I believe the most fruitful approach that unites upland and wetland perspectives, and local and broader-based views, is integrated river basin management. This approach also addresses transnational concerns such as dams and migratory fishes, accumulative downstream pollution, headwater deforestation and the efficacy of protected areas and indigenous territories to aquatic ecosystem conservation and management.

If we view conservation outlook through the lens of major river basins and the Amazon River mainstem, which includes its vast floodplains, then some of the large sub-basins, such as Tocantins, Xingu, Tapajós and parts of the Madeira drainage, will continue to be highly modified by deforestation, dams and mining and they will eventually require restoration. The blackwater basins, such as the Rio Negro, will be less impacted as a whole because of poorer soils for agricultural development, though they will still face threats from mining operations and headwater deforestation. The roads and agricultural and mining frontiers moving down all major Andes-Amazon tributaries present transnational challenges to river basin management and together present the potential western ‘headwater tipping point’ of the aquatic ecosystem.

Brazil is downriver of all Andean countries in the Amazon Basin, thus it should be as concerned with what is happening in the Andes as in its own territory. Likewise, the Andean countries need to look downstream as many fish migrations that enter their territories originate in Brazil. The lower Amazon River floodplain has been heavily deforested. If wetland deforestation continues upstream, it will have major impacts on aquatic biodiversity and production, not only on the mainstem but on its tributaries as well. The Amazon mainstem is especially problematic because it has few protected areas and indigenous territories that could help manage its floodplains. Even where there are protected areas, the river channels are not included.

Maintaining the health and productivity of the aquatic ecosystem for biodiversity and human wellbeing requires taking on a series of basic steps in a realistic time framework, which will probably be decades. First, is addressing the need to scale-up conservation initiatives to basin levels, including coordinated transnational levels where required. Second, the critical importance of wetland forests for fish and other aquatic biodiversity, and human wellbeing, requires explicit legislation and implementation of the same to protect these habitats from conversion to livestock ranches, rice fields or other types of large-scale agriculture. At present, the fisheries suffer from a lack of sound management and lack of data collecting. Overfishing is becoming the norm. Community management projects help inform local challenges, but it will take urban fish market monitoring and enforced regulations across the Amazon to control overfishing. The lack of statistical data for a resource as important as fish in the Amazon is indefensible, and considering the many impacts taking place, it becomes even more egregious.

All Amazonian countries now have excellent scientists addressing ecological and social issues related to the Amazon aquatic ecosystem or parts of it. This human capital is an amazing asset and governments need to recognize it as such to inform and mitigate infrastructure development and the proper management of aquatic resources on which biodiversity and human well-being in the Amazon depend. Therein lies optimism for the future.