Climate change is one of the most pressing global issue in contemporary times, and dams play a substantial role in aggravating it by becoming feeding grounds for methane-producing microbes. In addition, dams fragment rivers and disrupt their natural flow, threatening the survival of aquatic fauna, especially migratory species. Dams are also culpable for disrupting the biogeochemical cycles of river ecosystems, thereby impacting their function and structure. Taking all the environmental impacts of dams into account, the apparent economic gain from them may not be worth it. 

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In 2014, the dam in Canada’s Mount Polley mine gave way without warning, releasing 21 million cubic meters of mining sludge into British Columbia’s famed Quesnel Lake. In May 2020, Midland County in Michigan, US, was threatened with unprecedented flooding when two of its ageing dams – Edenville and Sanford – breached due to heavy rainfall. The unexpected flooding of downtown Midland resulted in the immediate evacuation of 10,000 people. In July 2020, China witnessed record-breaking rains that led a small reservoir in the Guangxi district to collapse. This incident was considered to be a harbinger, a “black swan” of future collapses in the country’s 94,000 ageing dams.

As disquieting as they may seem, dam failures are relatively common catastrophes in the 21st century, impacting the lives of hundreds of thousands of people and taking an irredeemable toll on the environment. This raises a pertinent question about their efficacy: “Is the environmental price of economic development through dams too high?”

Dams have often been referred to as the “temples of the modern economy’’ since they supplement agriculture, irrigation, water storage, flood control, and electricity generation. Considered symbols of economic prosperity, dams were constructed with great gusto in developing societies throughout the 1900s. However, this approach might have been slightly near-sighted, conveniently disregarding the ecological footprint of these massive reservoirs. Dams can directly or indirectly be responsible for soil erosion, species extinction, spread of diseases, sedimentation, salinisation, and waterlogging. Large dams may even be able to alter the Earth’s orbit, given the massive shifts in water distribution across several major river systems. As the world tries to make economic sustenance and environmental sustainability synchronous, it is imperative to accept the fact that dams may be fruitless, if not detrimental, to this attempt.

The Environmental Impacts of Dams

Dams are massive structures that retain water for domestic use, irrigation, hydroelectricity generation, and for use in industrial processes. However, when dams block the flow of water across a river, they trap enormous amounts of lake sediments in their reservoirs. Underwater microbes feed on the organic matter that gets accumulated in these sediments and produce methane, a potent greenhouse gas that significantly contributes to global warming. Additionally, dams lead to the fragmentation of rivers and the destruction of surrounding forests, inevitably eliminating valuable carbon sinks. 

Bridgit Deemer, a research associate at Washington State University, along with John Harrison, associate professor at the WSU Vancouver School of the Environment, wrote for the journal BioScience (2016) and concluded that “while reservoirs are often thought of as ‘green’ or carbon-neutral sources of energy, a growing body of work has documented their role as greenhouse gas sources.” Vincent St. Louis, a biogeochemist at the University of Alberta, Canada, was the first to calculate the total contribution of reservoirs around the world to greenhouse gas (GHG) emissions. “Whatever dam builders may say, reservoirs are not greenhouse-gas neutral,” said St. Louis. As per his calculations, reservoirs all over the world collectively contribute roughly 1.3% of the world’s annual GHG emissions, as much as the entire nation of Canada. 

Impact on Natural Flow and Riverine Biodiversity

Imagine this: a pod of emaciated Gangetic dolphins swimming lethargically along the Brahmaputra. The pod has been reduced to a mere few individuals and even those that remain barely manage to rise to the surface to breathe. The dolphins’ once lustrous skin, full bellies, and frequent leaps out of the water have been replaced with the struggle for survival. Those perpetual “smiles” on their faces effortlessly betray their ordeal within. Such is the life of India’s national aquatic animal as the country unceasingly builds dams on the Ganga and the Brahmaputra, the dolphin’s natural habitats. 

Dams alter the natural flow of the river, thereby fracturing the migratory routes of most fish. As fish are unable to spawn, predators like the dolphin cannot eat. However, this phenomenon extends beyond just the Gangetic dolphin; the Royal Bengal tigers, Indian rhinoceroses, Irrawaddy dolphins, Siberian cranes, Yangtze sturgeons, and countless other threatened species depend on an undisturbed river ecosystem for survival. 

As dams impede the flow of rivers, they also deter the flow of vital nutrients like carbon, nitrogen, silicon, and phosphorus along the nexus of the river and its tributaries. Sedimentation in the reservoir leads to increased nutrient retention upstream, depriving the downstream areas of nutrient-rich sediment altogether. 

Carbon is the primary constituent of all life on Earth, and a disruption in the flow between continental and oceanic carbon could have disastrous results. At the start of the 21st century, in-reservoir sedimentation wiped out 13% of the total riverine export of carbon to the oceans, and this value is expected to rise to 19% by 2030. The Amazon River, which supports the largest rainforest in the world, is expected to have 184 new dams by 2030, thereby increasing upstream carbon sedimentation 38-fold or 7% of global reservoir carbon accumulation. This could have disastrous impacts on the Amazonian ecosystem. As the downstream areas receive fewer nutrients, the soil gradually loses its fertility and is unable to support the flora and fauna of the region. Moreover, as fewer quantities of these nutrients flow into the ocean, algae, which are major carbon sinks, fail to bloom. This indirectly aggravates climate change. 

The environmental impacts of dams range far beyond those articulated above. The construction of large dams may even modify geo-environmental conditions, as in the case of the large-scale canyon deformations caused by the Xiluodu dam on the Jinsha River in China. Dams located in seismologically active geological zones, such as the Himalayas, pose a severe threat of flooding due to earthquakes, affecting millions of people and deteriorating land in their wake. All these reasons reaffirm that, unlike popular belief, dams are not “green”. 

Supporters of these projects would argue that dams allow for the preservation and storage of water, which, given the increasing pressure on the world’s freshwater resources, has become a necessity. Reservoirs created by dams can collect water for irrigation, industrial use, and human consumption. They might also argue that dams facilitate the generation of hydroelectricity, which is a much cleaner energy source compared to fossil fuels. Furthermore, tailing dams store toxic mining waste, thereby preventing it from leaching into the surrounding land. However, these arguments can be easily dismantled. 

Dams and reservoirs have a much greater surface area than the rivers that feed them and the nutrient-rich water in the reservoirs promotes plant growth. The water exposed to the sun and the plants’ transpiration speed up the process of evaporation, leading to immense loss of precious water. The world’s reservoirs lose about 170 cubic kilometres of water to evaporation every year, the equivalent of 7% of all freshwater consumed by human activities. Thus, the belief that dams help in the preservation of water is erroneous. 

What’s more, hydroelectricity is not as clean as it seems. Decaying vegetation and nutrient sedimentation in the reservoir lead to increased microbial activity, which results in massive GHG emissions. “It would be a grave mistake to continue to finance those [dams] with the impression that they were part of the solution to the climate crisis,” said Kate Horner, executive director of the environmental group International Rivers. 

Another counterargument is that, although tailing dams store noxious mining sludge, they have a very high failure rate. Dam breaches are more frequent than one might think, and toxic metals often escape into the soil via microbial action or acid drainage, thereby undermining the utility of the dam.

Conclusion

Many would argue that economic growth should be a nation’s foremost priority, and hence, any means adopted to achieve that stands justified. However, as the world currently deals with global warming – one of the most challenging battles in human history – it is imperative that we not only reconciles with the long-due ramifications of our actions but also works towards a more sustainable relationship with nature. 

Undoubtedly, dams have numerous short-term economic benefits, but these stand null and void if they come at the expense of the environment. These water bodies were formed and have sustained over millions of years. Perhaps, it is time to acknowledge the fact that they survived for reasons far beyond human comprehension. Everything in nature is so intricately balanced that a massive imposition like a dam could have unimaginable consequences. What use is economic development if people forever remain susceptible to catastrophes and animals struggle for existence? The irreparable damage inflicted upon the environment will ultimately befall humanity in the years to come, reversing decades of economic growth in mere seconds. This utilitarian approach to our planet is terrifying and must change, now more than ever. 

The dam failure in Canada’s Mount Polley mine, the unexpected flooding of Midland County in Michigan, and the breach of the reservoir in China’s Guangxi district are not a set of sporadic incidents. Dam failures have always been in tandem with the construction of dams and will continue to be as long as their environmental costs are not given due consideration. 

Nevertheless, there is light at the end of the tunnel. Strategically planning the construction of dams on rivers, such that human needs are met with minimal damage to the environment, is the way forward. Significant change can also stem at an individual level. Simply voicing concerns regarding the construction of new dams by signing petitions will build pressure on the authorities concerned to take cognisance of the environmental impacts of these projects. 

Dams are established to meet the ever-increasing energy and water demands of the population; therefore, small efforts to conserve power and water can go a long way. By refusing to contribute to recreational economic activities like boating and fishing, we can dissuade their growth in the future. Although the ultimate goal may seem daunting, it is crucial to remember that every contribution, no matter how small, makes a difference.

You might also like: Exploring the Most Efficient Solutions to Water Scarcity

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Orca calves in the Valdes Peninsula, Argentina, and the Crozet archipelago in the Indian Ocean have learned the intentional stranding hunting technique through the physical and biological dynamics of their pod, the reason for which we often refer to them as killer whales. The rarity of orca beachings, the passing down of this trait from one generation to the other, and its association with mass cetacean strandings and orca speciation can be explained by this wondrous phenomenon. 

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Aptly referred to as the “wolves of the sea,” orcas are apex predators with highly specialised predation techniques that are cascadingly linked to the fluctuation of prey populations and the intricacies of their ecosystem. While most feed on fish and squid, some pods have been known to attack even dolphins and adult whales, giving them their often-misunderstood name: killer whales. 

Orcas are social animals, with populations composed of matriarchal pods. Being a cosmopolitan species, they can be found in all of the world’s oceans and a variety of marine ecosystems. Their preeminence in the aquatic food chain can be attributed to their highly sophisticated and refined hunting strategies. However, like most animal species, orcas have adapted themselves to their environmental specifications, and these adaptations are passed across generations. One such manifestation of this animal culture is the development of the intentional stranding hunting technique in select pods of orcas in the southern Indian and Atlantic Oceans. 

Killer whales in the Valdes Peninsula, Argentina, and the Crozet Islands in the Indian Ocean are famous for intentionally stranding themselves in their pursuit of seals and sea lions. The pursuing whales exploit the thrust of the waves, supplemented by their own momentum, to lunge at perplexed seals sunbathing on the gravel beaches. They then thrash their bodies and wait for the next wave to carry them back into deeper waters. 

While most feed on fish and squid, some pods have been known to attack even dolphins and adult whales, giving them their often-misunderstood name: killer whales. 

This behaviour was first observed in the 1970s in Argentina, and then hundreds of times more within the same pod, suggesting the passing down of an “intellectual heirloom” from one generation of orcas to the other. It is this fact that, perhaps, begs the question: How do orca calves develop the intentional stranding hunting technique?

Three significant factors contribute towards the development of the intentional stranding hunting technique in killer whale calves: high parental investment in the teaching-learning process, low reproduction rates among the Crozet Islands and Valdes Peninsula females as compared to those in other locations, and the social transfer of skills through alloparental apprenticeship. This peculiar hunting strategy has an intriguing implication. Killer whales appear to be splitting up into several species because of the vast cultural and strategic differences between populations. As orcas speciate, their ability to reproduce becomes restricted to their own kind, thereby suggesting a possible threat to their numbers in the future. Studying characteristic orca behaviour like intentional stranding can help scientists assess the potency of this threat and make planned and targeted conservation efforts if a future need arises. 

It comes as no surprise that the calf’s mastery of this potentially life-threatening technique requires high time and energy investment by the mother to reduce the associated risk. At the Crozet Archipelago, juvenile orcas first independently experimented with intentional stranding at the age of four or five; however, even six-year-old juveniles depended on their mothers to return to the deep water with their prey. 

Often, calves accidentally beach themselves ashore and struggle under their body weight. Their mothers would then have to accelerate towards the beach, turn abruptly, and produce an artificial wave massive enough to lift the calf, who then managed to swim back into deeper waters. Orca mothers frequently assist the calves in launching the attack as well, thereby, teaching by example. When a calf pounces at unsuspecting seals, its mother gives it a push with her rostrum towards the prey, positioning herself between the beach and her calf to prevent it from going too far ashore. She then pushes the calf and its prey back to the ocean with the front part of her body. Thus, the mother’s investment in assisting her calf through possibly fatal hunting techniques enhances the calf’s survival by reducing the risks associated with predation. 

While killer whales in the wild breed every three to ten years, the Crozet Islands and Valdes Peninsula orcas have much longer time gaps between offsprings. This unusually low fertility rate allows the mothers to devote more time and energy to the physical development and hunting apprenticeship of their calves. For instance, seven-year-old juveniles near the Possession Island of the Crozet archipelago were still closely associated with their mother, while in the North Pacific, calves started distancing themselves from their mothers beyond three years of age. A similar trend was observed in the Argentinian orcas. Thus, low offspring production is directly linked to high investment in the skill development of the calves, especially with regard to the intentional stranding technique. 

It is not solely the mother that facilitates the development of the skill of intentional stranding in young juveniles. Orcas live in matrilineal pods, with all females living in close kinship and contributing to the upbringing of the calves, whether it be through social play or alloparental teaching. Through social beaching play, adult females teach calves socialisation and innovation to refine their hunting tactics. Through intimate contact, interaction, and emulation of the predation behaviour of its mother or other relatives who have perfected specific skills, the calf learns essential hunting strategies. This information transfer, social learning, and alloparental behaviour patterns not only benefit the calves, but also significantly improve the predation success rate of the pod. Thus, apprenticeship and social play with other females play an essential role in the transmission of predation strategies from one generation to the next.

The Future of Species Adaptation

The development of adaptation skills in any species is an evolutionary process spanning millions of years and decades of research. A few interesting questions, that deserve to be answered, also arise. What prompted the need for such a behavioural adaptation in the Crozet Islands and Valdes Peninsula orcas? How does the hunting strategy affect the native ecosystem, the food chain, and the orcas themselves? What other unique hunting strategies do animals in the wild possess? Are they somehow related to the intentional stranding technique of the orcas? 

Perhaps, having answers to such questions would help us comprehend the intricacy of ecological balance in nature, how human intervention affects it, and what can be done to safeguard it. 

You might also like: How Top Predator Decline Is Altering South Africa’s Marine Ecosystem

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Traditional and scientific knowledge have always been at odds when it comes to conservation science. However, neither is better than the other. Prudence lies in acknowledging the benefits of integrating these two sources of knowledge, each complementing the other, when it comes to biodiversity preservation, ecosystem restoration, and the climate change agenda. 

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Sustainable development and harmonious co-existence with nature are the ultimate objectives of the 21st century. However, these goals are marred by questions about whether we possess the necessary knowledge to do so. While it has been a common notion that the answers lie within modern science and technology, it is now becoming increasingly evident that traditional knowledge also has unique and critical insights to offer. It is precisely through this dynamic integration (not competition) of the two realms of thought, that one can hope to strive for sustainability. Both sources of knowledge possess equal relevance and pragmatism and must complement each other in order to further humanity’s objectives.

There is no dearth of examples to support this confluence. After the removal of two large dams in the Elwha River basin in Washington, the efforts of the scientific community, coupled with the traditional knowledge possessed by the Lower Elwha Klallam Tribe, led to the restoration of the river system. The United States Geological Survey, the National Park Service, and Western Washington University sought the tribe’s centuries-old knowledge of the river’s fisheries and ecosystem to bring it back to its original glory. The return of the water birds, salmon, and numerous other species exemplified how a systemic assimilation of traditional and scientific knowledge can reap enormous environmental benefits.

Traditional knowledge may also hold the key to solving this century’s greatest challenge: climate change. Indigenous communities rely on natural resource security for their survival, and have learned to live sustainably amongst nature. They are keen observers and interpreters of alterations in the environment, and hence, can play an extensive role in climate change discourse. Their collectively-held knowledge complements scientific data with chronological and region-specific accuracy, which is essential for verifying existing climate models developed at a much more universal scale. Moreover, their knowledge can help scientists plan crucial community-based adaptation plans and mitigation actions for at-risk habitats and ecosystems.

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For instance, in Tasmania, warming waters have led to a loss of more than 95% of the country’s giant kelp forests. These kelp forests were home to hundreds of marine species, particularly the rainbow mariner shells, which are an iconic symbol of the Tasmanian Aboriginals. Marine biologists and aboriginal communities are collaborating to restore the kelp forests through the remaining 5% of kelps that still stand, thereby, providing a ray of hope for the mariner shells and other kelp-dependent species. Thus, such a partnership between the two sources of knowledge is not only helping restore a climate change-afflicted ecosystem, but is also preserving the millennia-old cultural identity of an indigenous community.

The conjunction of scientific and traditional knowledge can also guide community decision-making and help find solutions to problems that may halt people’s livelihoods. For instance, The East Trinity Wetland in Australia is home to numerous sugarcane plantations. However, industrial contamination led to acidification of the soil to such an extent that no plant could possibly survive. To address the acidity, government ecologists and biologists worked with the Indigenous Land and Sea Country Rangers of Djunbunti, and eventually nurtured the land back to life.

In fact, traditional knowledge has even helped further its scientific counterpart. In 2018, a team of researchers in northern Australia documented falcons and kites, colloquially called “firehawks”, intentionally carrying burning twigs to spread fire. While it was already known that predatory birds take advantage of fire to feed, the intentionality of this act astounded the entire scientific community. Such a behaviour of the firehawks, while new to Western Science, has long been known to the MalakMalak, Jawoyn, Alawa and other indigenous tribes of northern Australia. One can only imagine how many more such discoveries can be uncovered if scientific research is increasingly rooted in traditional knowledge.

In an ideal world, such an alliance between traditional and scientific knowledge should be ubiquitous. However, it doesn’t come without challenges of its own. The question of indigenous land rights and inadequate remedial actions can prevent the incorporation of traditional conservation practices and resource management techniques into existing scientific dialogue. Another obstacle to this collaboration could be the differing perceptions of reality that the indigenous and scientific communities possess. While the former embody the concept that nature is an aware agency of her own, the latter have often found such insights quite implausible and even anecdotal. This difference in perspective could, quite possibly, serve as a point of conflict.

Clearly, integrating traditional and scientific knowledge is not always easy, but it is certainly possible. A plethora of examples, like the ones presented above, can attest to the immense environmental, economic, and cultural benefit one can reap through a successful alliance of the two. Neither one of the two schools of knowledge holds more weight than the other; we need a congenial combination of the two in order to tackle humanity’s troubled relationship with nature.

More on the topic: The Role of Indigenous Knowledge in Climate Change Adaptation In Bangladesh and the Philippines

The post Traditional vs. Scientific Knowledge in Conservation Science: Is One Better than the Other? appeared first on Earth.Org.