According to just released Living Planet Report 2016, the loss of habitat is prime reason behind declining of wildlife species found in and around wetlands, rivers and lakes due to increasing fragmentation, pollution and destruction of these ecosystems. Data in report also underlines that the global water crisis is real and water requirements worldwide will go up by 40 per cent by 2030.
The report emphasizes habitats based on rivers, wetlands and lakes command high economic, cultural, aesthetic, recreational and educational value. At the same time, these habitats are challenging to conserve because they are strongly affected by the modification of their river basins as well as by direct impacts from dams, pollution, invasive aquatic species and unsustainable water extractions.
Further, fresh water based habitats often are beyond administrative and political boundaries; warranting the extra effort for collaborative forms of protection. The report refers to several studies which have found that species living in freshwater habitats are faring worse than terrestrial species.
The report notes that Brazil, Russia, India, China and the United States (a different BRICS) account for nearly half of the planet’s total bio-capacity. These few countries function as global bio-capacity hubs as they are among the primary exporters of resources to the other countries. This results in great pressure on ecosystems in these countries, contributing to habitat loss.
This account summarizes the key findings of the report in context of threats and impacts over fresh water sources and species.
Fresh Water Species
Freshwater accounts for only 0.01 per cent of the world’s water and covers approximately 0.8 per cent of the Earth’s surface but provides a habitat for almost 10 per cent of the world’s known species.
The Living Planet Index shows a decline of 58 per cent between 1970 and 2012 with greatest losses in freshwater environments. The report mentions that during these years a decline of 81 per cent has been recorded in fresh water wildlife species across the planet Earth which is double than observed in land (38%) and marine (36%) populations within same time frame. These figures are based on data for 3,324 monitored populations of 881 freshwater species.
Notably in 1970 fresh water based ecosystems were already heavily-altered and the report observes subsequent trends and changes. Also, like Living Planet Report 2014, the present data suggests an ongoing downward trend for degradation of wild animal habitat.
According to the report, for freshwater bird, mammal, fish and reptile populations, habitat loss is the most frequently recorded threat, followed by over-exploitation. Among mammals, river dolphins are declining rapidly due to unintentional over-exploitation. Direct over-exploitation through unsustainable fishing or collection for commercial or subsistence purposes is the second most frequent threat to freshwater populations (24 per cent), followed by invasive species and disease (12 per cent), pollution (12 per cent) and climate change (4 per cent).
The report finds that apart from direct human interventions, fresh water species also face threat from indirect reasons e.g. deforestation that can increase river sediment load, leading to more erosion of the river’s bank with subsequent changes in the water quality and flow.
The global analysis of fish population trends shows that on average, the abundance of fish species that migrate within freshwater habitat or between freshwater and marine habitats declined by 41 per cent overall between 1970 and 2012, with an average annual decline of 1.2 per cent. The index is based on 162 species and 735 populations. Although threat information for many of the populations was unavailable, of the 226 populations for which threat data is available, nearly 70 per cent are threatened by alteration of their habitat.
Data analyses for wetlands mention that about 87 per cent of wetland area may have been lost over the last 300 years of which 30 per cent (including 27 pre cent inland and 38 pre cent coastal wetland) has been lost in last 40 years alone. The report cites reclamation of land for agriculture as single biggest reason behind loss of wetlands globally.
The reduction of wetland area directly affects wetland-dependent species since they will face reduced habitat availability and increased competition for food and other resources. The report claims that wetland dependent species have suffered an overall 39 per cent reduction in abundance between 1970 and 2012, with an average annual decline of 1.2 per cent.
On the positive side from 2005 onward the Living Planet index on wetland dependent species is slightly increasing as several bird species have benefited from improved foraging opportunities resulting from changes in agricultural practices in staging and wintering areas along their migration routes in North America and Europe.
At present, 41% decline has been recorded in migratory fish species between 1970 and 2012 mainly because of fragmentation of river courses. There has been increase in migratory fish population since 2000 in European regions due to environmental policy under which fish passes have been widely installed. An improvement in water quality of rivers in the region has also been reported.
Of all human interventions, the report observes dams as having severest impact on rivers ecosystem as they alter flow, temperature and sediment transport of rivers. Furthermore, dams inhibit migration, affecting the regular movement and distribution of species.
The report sums up that almost half of world river flows are subject to alterations due to abstraction or channel modifications or fragmentation by weirs and dams. Raising concerns further the report sees continued rise in such river modifications since there are around 3700 major dam projects in pipeline across the globe and many of them are coming up on ecosystems already under mounting pressure. The map in the report shows that large concentration of these proposed dams are in India.
It is well known that rivers have been extensively altered for urban development, transportation, flood protection, water supplies or energy generation. Almost half (48 per cent) of global river volume is already altered by flow regulation, fragmentation, or both. Completion of all dams planned or under construction would mean that natural hydrologic flows would be lost for 93 per cent of all river volume.
Signifying critical role of forests for rivers the report says that health of forest determines the functioning of the rivers. Because forested land across the world influences rainfall, filter fresh water and prevent flooding and soil erosion. While the pressures on forests vary across regions, the biggest cause of deforestation is expanding agriculture. Also dams, hydro electricity, mining and other infrastructure projects are leading factors behind deforestation and degeneration of forest lands. The report finds that construction of new roads alone can expose forests to a large indirect impact like opening up forests to settlers and agriculture which also adversely affect rivers in long term.
Inspiring example of Elwha River dam removal: In the mid-1980s the Elwha Klallam Tribe and environmental groups started to push for the removal of the Elwha and Glines Canyon dams. Eventually the Elwha River Ecosystem and Fisheries Restoration Act of 1992 was put in place, mandating the “full restoration of the fisheries and ecosystem”. After 20 years of planning, work to remove the Elwha Dam began in 2011, the largest dam removal in US history. The removal of the Glines Canyon Dam was completed in August 2014. Fish populations are expected to make a return to the river. Some chinook salmon already did in 2012, just after the Elwha dam came down.
The report says that humans have substantially disrupted hydro-logical systems through rising consumptive use and impoundment of water. As a result, streams, wetlands and lakes have dried regional atmospheric vapour flows. Increased reservoir storage has also caused decline in flow in the rivers. Changing the water cycle has been affecting both the climate and the biosphere at regional level.
Agriculture and Water
The report also highlights that nitrogen run off from farming activities pollute fresh waters apart from coastal zones. Similarly, much of the phosphorus used in agriculture by humans is ending up in aquatic systems. As a result, rivers, lakes and other water bodies are experiencing oxygen-starvation. Because the bacteria consume decaying blooms of algae which is growing abundantly in response to the high nutrient supply reaching in inland water sources through chemical farming. Further a significant amount of applied nitrogen and phosphorus makes its way to the sea, where it pushes marine systems into higher risk conditions. Remarkably sharp rise in water intensive farming and changing cropping pattern all over the world is also exhausting the underground aquifers at alarming pace.
Land Use Change
All over the planet, forests, grasslands, wetlands and other habitats have been and continue to be converted first to agricultural and then in urbanized landscapes. The resulting habitat loss is a serious driving force behind reductions in biodiversity. Land conversion also holds consequences for water flows and for the bio-geochemical cycling of carbon, nitrogen and phosphorus and other important elements.
Ocean acidification has increased atmospheric CO2. As around a quarter of the CO2 that humans release into the atmosphere is ultimately dissolved into the oceans, acidification is altering ocean chemistry and decreasing the pH (increasing acidity) of the surface water. Surface ocean acidity has already increased by 30 per cent since pre-industrial times.
Plastic is emerging as a serious anthropogenic disturbance to the earth water system. Concerns are growing over the quantity of plastic waste, in particular the micro-plastic debris reaching the ocean though waterways apart from causing tremendous pollution to rivers, wetlands and lakes.
River basin management: Societies throughout history have gone to great lengths to exploit river resources by building dams, diverting water to irrigate agricultural land and using rivers as sewers of first resort. Such approaches have certainly brought some social and economic benefits. But they have also fragmented rivers, interrupted the seasonal flows of water and caused massive pollution.
Unfortunately, rivers have typically been managed in a piecemeal fashion with insufficient consideration of the cumulative impacts of development. A strategic, basin-level approach to management by governments, communities and businesses can optimize the balance between water resources development and maintenance of critical ecosystem functions. It can also help to minimize costly restoration activities in the future.
Bhim Singh Rawat (email@example.com), SANDRP