Download Annotated Scientific Reference Assignment Antonius

Annotated Scientific Reference Assignment
Antonius Siregar
NRS 534 Ecology of Fragmented Landscapes
Impacts of Dams on Inland Fisheries
Most of the major commercial fish stocks are presently (or are close to being) overfished, the
growing international trade in fish and fish products is likely to have major implications for food
security and livelihoods across the developing world, while regulatory initiatives at both the national
and international level need to be further refined if resource sustainability and ecosystem protection
objectives are to be met (Thorpe et al). Some overall indicators, such as disappearance of certain
important species and continuous reduction in the size of harvested fish, indicate that the fishery is
not being exploited on a sustainable basis
Inland fisheries are directly related to food security, particularly in Asia and Africa where they
provide food, income, and employment on a large scale. However, most inland fisheries are
currently facing several problems which are very diverse and complex. Fish stocks are affected by
several factors including, river engineering (dam development, impoundments, land drainage, flood
control), habitat loss through land reclamation and removal of riparian vegetation, afforestation,
introduction of non-native species, overfishing and climate change. In particular, the problems
associated with the management of inland fisheries coming from dam development that increasing
lately. Therefore, after seeing the latest trend it needs to mitigate and minimize the impact of dam
development on fisheries.
Landscape connectivity in ecology is, broadly, the degree to which the landscape facilitates or inhibit
movement among resource patches. In terms of hydrology, it can be determined as the transfer of
matter and energy via water in any element of the hydrologic cycle, which includes living biota such
fish. Biological reserves are significantly influenced by what is happening in the surrounding
watershed and flow regime (Pringle, 2001). Changes to hydrologic connectivity that occur outside
the reserve, but within the watershed, are often affected the fishes habitat and the life cycle.
In aquatic ecosystems, river connectivity impacts species in various aspect. the impact on habitat can
be seen on access to floodplain habitat, a temperature of shallow and deep water, conversion of
lotic habitat. furthermore, it also affected the life history that is spawning, mating, and emergence
cues, as well as seed dispersal, migration from Upstream/downstream movement of diadromous
fish, are dependent on unaltered flow regimes. Inability to move across obstructed rivers hinders the
success of endemic species and favors generalist species lead to decrease the fish stock biomass in
natural habitat (Bunn and Arthington, 2002).
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer,
and over distances ranging from a few meters to thousands of kilometers. Fish usually migrate to
feed or to reproduce. Dams development pose threats to freshwater fish diversity, where such dams
profoundly modify riverine habitats. Furthermore, in detail Kano et al. (2016) explained that dams
will limit connectivity along river channels, disaggregating entire drainages into fragments, isolating
fish populations and blocking their migrations. Dams also disrupt downstream flood cycles, limiting
the extent of floodplain inundation and thereby reducing fish production. Longitudinal transport of
sediment, nutrients, and carbon are also affected with downstream consequences such as delta
shrinkage and saline intrusion that will be worsened as sea levels rise.
In the study by Dugan et al (2010) suggest Mekong mainstream which has over 50 species, millions
of individuals, and biomass that is much greater than that can be found today in the rivers of Europe
and North America. Most of the current fishway technology are develop base on river characteristic
in Europe and North America which has a different condition from Mekong River basin. On this basis,
if this is not addressed, then the large part of the river’s fish production, the economic, nutritional
and social benefits of this ecosystem service will be lost in the coming decades.
One of the recommended approaches to overcome the negative impact of dam construction is
tradeoffs. A trade-off is a situation that involves losing one quality or aspect of something in return
for gaining another quality or aspect. More colloquially, if one thing increases, some other thing
must decrease. Consider the tradeoffs If we have to put in dams, we should figure out how to limit
threats to biodiversity and fisheries while still harnessing maximum hydropower. We need to find a
balance between economic prosperity and environmental integrity. Dams significantly restrict
hydrologic connectivity and we need to consider tradeoffs.
Annotated Bibliography
Pringle, Catherine M. "Hydrologic connectivity and the management of biological reserves: a
global perspective." Ecological Applications 11.4 (2001): 981-998.
The author of this paper writes about hydrology alteration that affected the biological connectivity,
where most of the alteration process are human activity. Hydrological connectivity is not just about
the flow of water but also elements that follow such as energy, materials, and biota in a continuous
cycle. The paper presents riverine connectivity influence on ecosystems habitat and biodiversity
which human activity through several activities have disturbed the hydrologic connectivity. The
authors give examples of human-dominated landscapes impact ecosystems and how human activity
or development have changed some watershed systems in the world today. It is important to see
that the watershed should be seen as a whole entity that connected to each other, and should be
managed on hydrologic connectivity. Which policymakers need to work together to overcome
political and cultural boundaries based on input from academics.
World Commission on Dams. Dams and Development: A New Framework for Decision-making: the
Report of the World Commission on Dams. Earthscan, 2000.
The report published by the commission is noted for its comprehensive overview and thorough
assessment of dams globally. According to the International Commission on Large Dams (ICOLD), a
large dam is defined as having a height of 15 meters or more from the foundation. If a dam is
between 5-15m and has a reservoir that holds >3 million cubic meters of water than it also is
considered a large dam. By the end 20th century, there were over 45,000 large dams in over 140
countries. Major uses of dams are for irrigation, industry, energy/hydropower, flood control, and
recreation purpose. Dams provide services for sustainable development but it also generate many
negative effects on ecosystems. Large dams have a mostly negative impact on ecosystems the
impacts are complex, varied and often profound in nature. A substantial loss in downstream fishery
production as a result of dam construction has been reported around the world. Mitigation has been
used to reduce the impacts of changes in fisheries but the results are still limited.
Kano, Yuichi, et al. "Impacts of Dams and Global Warming on Fish Biodiversity in the Indo-Burma
Hotspot." PloS one 11.8 (2016): e0160151.
The authors of this paper present the study of hydropower dams and global warming on fish
biodiversity. the study conducted by plotting the locations of existing and planned dams within the
Indo-Burma Region on GIS software. Then the data is interpolated with fish distribution data in
Cambodia, Laos, Thailand, and Vietnam. The analysis is done using the generalized additive modeling
(GAM) to compare general trend and predictive accuracy the dam scenarios and global-warming
scenarios. Based on scenario projected by model the river fishes will be affected by the construction
of dams in Laos immediately, upstream of the Cambodian national boundary with greatest declines
in the mean species richness. The data suggest that construction of dams on the lower Mekong
mainstream would impact fish diversity and give rise to transboundary effects that would be felt in
countries in the Mekong rivers. Furthermore, presence of dams will exacerbate the impacts of
warming because they prevent fishes from making range adjustments in response to rising
temperatures.
Dugan, Patrick J., et al. "Fish migration, dams, and loss of ecosystem services in the Mekong
basin." Ambio 39.4 (2010): 344-348.
Dams development in Mekong River recently has raised concerns about the sustainability of the
fishery because it will likely disrupt fish migration. This study is an assessment of the impact of
mainstream dams on fish migration and people’s who depend upon them for food and livelihoods.
This study is done by reviewing information on ecological characteristics of fish species in the
Mekong, as well as experience in designing and operating hydroelectric dams from other regions in
the world. Based on the research result, about 40–70% of fish in the Mekong are species that
migrate long distances along the Mekong mainstream and into its tributaries, and these fish stocks
will be vulnerable to dams built. This will have an impact on people livelihoods especially in the lowincome communities of Cambodia, Laos, and Vietnam that can lead to an increase of social conflict
and rural-to-urban migration in search of employment. Besides that, experiences from other regions
suggests that the probability of successful adaptation by fishing communities in the face of
ecosystem degradation is low. It is necessary for government agencies to invest in diversifying and
strengthening livelihoods so that the poor are better able to cope with the changes arising from
dams development. Future research is required to develop fish passage technology in accordance
with the species and hydrological conditions of the Mekong.
Ziv, Guy, et al. "Trading-off fish biodiversity, food security, and hydropower in the Mekong River
Basin." Proceedings of the National Academy of Sciences109.15 (2012): 5609-5614.
Ziv et al. used fish migration modeling to examine proposed dams on Mekong river basin. Mekong
fish fauna can be roughly classified into two guilds which are long-distance migratory and
nonmigratory species. Between migratory fish biomass, calculated based on the 48 dominant
species, calculated based on predicted population declines for all species. They found that compared
to main stem dams, tributary dams are more harmful to fish biodiversity and productivity. This
happens because dams will block critical fish migration routes between the river’s downstream
floodplains and upstream tributaries. Therefore, it would have catastrophic impacts on fish
productivity and biodiversity. This article suggests the trade-off approach to managing uncertainty
from dams development.
Kareiva, Peter M. "Dam choices: analyses for multiple needs." Proceedings of the National
Academy of Sciences 109.15 (2012): 5553-5554.
This article provided a summary and overview of hydropower projects in South America. Dams can
be an important source of clean energy and for poor nations. However, biodiversity of the Amazon
Rainforest is threatened by proposed dams. The electricity harvested at many of these dams will
mostly be used for industrial expansion. Moreover, wherever these dam projects are planned, there
are issues of food security for downstream human populations. Because, when dams cut floodplains
off from their natural flows, this production is severely reduced floodplain fisheries average from
2,000 to 200 kg of fish production per year.
Erkan, D. 2002. Strategic Plan for the restoration of anadromous fishes to Rhode Island coastal
streams. Completion Report in Fulfillment of Federal AId in Sportfish Restoration Project.
Erkan present an ecological benefit of dam removal which includes enabling the return of native
species, the decrease of lentic biota and increase of lotic biota, restore the wildlife habitat, and can
improve water quality. This project is based on the situation that shows that most dams in New
England were put in for power needs during the Industrial Revolution and the majority is no longer
serve their original function. Alewife, blueback herring, Atlantic salmon, American shad and more
migrating fish are hindered by old dams. The RI DEM has conducted an extensive analysis of
watersheds in RI that can restore or establish fish populations through the removal of dams. Project
implemented on watershed identified with significant habitat for salmon and significant water
withdrawals for turf farm. Using watershed approach the project identified all obstructions and the
most cost effective approach to improve fish passage. The project expected to give very positive
anadromous fish impact and creating unrestricted habitat for wildlife.