The IPBES opined that the ‘economic repercussions of biological invasions are predicted to quadruple every decade, and, therefore, initiating proactive and decisive actions on emergency mode is crucial to curtail the adverse effects of invasive alien species (on ecosystems)’
By Salam Rajesh
“Climate change will have direct and second order impacts that facilitate the introduction, establishment and the spread of invasive species”. This hard-hitting statement comes from a study by scientists looking at the interconnectivity of climate change process and invasive alien species within ecosystems, with the larger perspective on biodiversity loss and impacts on livelihoods.
Authors Burgiel and Muir in their study ‘Invasive Species, Climate Change and Ecosystem-Based Adaptation: Addressing Multiple Drivers of Global Change’, under an initiative of the Global Invasive Species Programme, observed that, “Climate change impacts, such as warming temperatures and changes in CO2 concentrations, are likely to increase opportunities for invasive species because of their adaptability to disturbance and to a broader range of bio-geographic conditions and environmental controls”.
The Intergovernmental Panel on Climate Change (IPCC, 2002) estimated that the mean surface temperature had increased by around 0.6 degree Celsius on average over the past century, and by the next century it predicted that the global average warming as compared to the pre-industrial era will be between an increase of 1.1 to 4.6 degree Celsius, which is of course alarming. This comes in the backdrop of observed increases in ocean temperature with an estimated average increase of 0.10 degree Celsius between 1961 and 2001 (IPCC, 2007b).
The connection between accelerated temperature rise and increased phenomena of invasive species is seen in sequestration impacts on important ecosystems. For instance, the study emphasized that invasive species “may have a feedback effect that further exacerbates climate change. Invasive species can compromise the ability of intact ecosystems to sequester carbon which helps offset greenhouse gas emissions”.
In short, large scale spread and proliferation of terrestrial and aquatic invasive plant species can have considerable impact on the carbon sequestration capacity of forest and wetland ecosystems.
Two other key messages in the study forewarned that, “Invasive species can increase the vulnerability of ecosystems to other climate-related stressors and also reduce their potential to sequester greenhouse gasses”, while suggesting that, “Using an ecosystem-based adaptation approach, these pressures on ecosystems and their ability to provide important services can be offset by preventing the introduction of new invasive species and by eradicating or controlling those damaging species already present”.
In-between, an assessment of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) observed that given the assumption that nations continue on a business-as-usual attitude to the emerging issue, an anticipated increase of 30 percent in alien species will occur by the year 2050 if preventive measures are not taken up in time.
Furthermore, the IPBES opined that the ‘economic repercussions of biological invasions are predicted to quadruple every decade, and, therefore, initiating proactive and decisive actions on emergency mode is crucial to curtail the adverse effects of invasive alien species (on ecosystems)’.
Burgiel and Muir’s study assessed that the estimated damage from invasive species worldwide totals more than 1.4 trillion USD annually – which is, 5 percent of the global economy – with impacts across a wide range of sectors including agriculture, forestry, aquaculture, transportation, trade, power generation, and recreation.
Quite interesting is the fact that an aquatic plant species that is seen commonly in most water bodies – the water hyacinth – features as one of the most pervasive alien invasive species across most continents. As much as hyacinths have some beneficial properties, they are considered as nuisance plants in Manipur’s water bodies, and equally find bad mention across India, Bangladesh, Asia, Europe and the Americas!
Native to tropical and subtropical South America, water hyacinth has been present in the African Great Lakes since the late 1980s, and was first reported in Lake Victoria in 1990. Presumably, the free-floating perennial aquatic weed thrived and spread over time due to its fast growth rate and surrounding anoxic and high nutrient water conditions. Boats, machinery and water currents aided the distribution of water hyacinth while human carriers spread it as ornamental flowering plant. It is believed British officers brought hyacinths to India as ornamental plant.
Water hyacinth (Eichhornia crassipes), originally perceived as a practical problem for fishing and navigation, is now considered a threat to water availability, and biodiversity. In fact, hyacinths are currently considered as one of the world’s worst aquatic weeds. Recent research on how water hyacinths respond to climate change has implications for the continued spread and management of a known invasive weed that is present in 50 countries across five continents.
Scientists studying the process of spread of hyacinths across most water bodies throughout the globe opined that one of the most important impacts of water hyacinth is water loss, where this aquatic plant significantly increases water loss by high rates of evapo-transpiration, as much as 2.7 to 3.2 times greater than water loss in open water.
The impact of the highly invasive water hyacinth is also far-reaching, insomuch as it interferes with fishing activities, boating, irrigation, water treatment, hydroelectric power, human health, tourism, and on the water bodies’ natural ecosystem. This evidently is observed in Manipur’s inland freshwater Loktak Lake which is over-ridden by several alien invasive species of semi-terrestrial and aquatic plants.
Dense mats of water hyacinth evidently interfere with the traditional fishery in Loktak Lake as it reduces the open water body available for the fishing activities while hampering in movement of the fishers in their traditional dugout canoe. Mass accumulation of water hyacinth acts as breeding ground for mosquitoes that may transmit malaria, and could contribute towards other water-borne diseases.
The more perflex suggestion based on projections of various climate change factors is that water hyacinth could likely expand its global distribution with increased temperature rise. Providing an example, scientists opine that water hyacinth is currently established in parts of southern Europe but could readily expand to the rest of the Mediterranean Basin and further northward into Europe pending rates of global warming (EPPO, 2008).
Scientists studying the process also opine that the ‘uncertainty over the role of El Niño raises additional questions about the implications for climate change on water hyacinth’. Research studies suggest that ‘warmer temperatures in the region will have adverse impacts on water hyacinth as its growth rate is retarded above 30 degree Celsius’, while others indicate that ‘increased carbon dioxide concentrations can increase the biomass of water hyacinth under controlled conditions’.
The several deliberation on the subject matter comes up with the suggestion for measures like prevention of new introductions; close the pathways for the unintentional introduction of non-native species; conduct risk assessments of proposed introductions of non-native species that include bio-geographical factors and potential climate scenarios; and to develop early detection and rapid response systems targeting likely pathways and points of introduction, taking into account climate change dynamics.
The other suggested measures are simplified, that is, eradication and control: eradicate invasive species already present in a system where feasible; control known invasive species and as necessary damaging native species if eradication is not feasible; and to monitor known invasive species as well as suspect non-native and native species with the potential for biological invasion.
In view of the national and global concerns on invasive species as inducing biodiversity loss, impacting livelihoods and contributing to climate change process, Manipur Government needs to come up with a state policy on how to deal with the issue. Loktak Lake, as well as most water bodies in the State, is already deep in trouble from invasive species.