Steady increase in hot days in Northwest and Southeast India in recent years: claims study

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The 2019 Indo-Pakistani heat wave across north India and Pakistan( Credit: NASA Earth observatory/ Wikimedia Commons)

According to a study conducted by the researchers from Indian Meteorological Department (IMD) and the Indian Institute of Technology, Delhi (IITD), there was a steady increase in the occurrence and duration of hot days in the Northwestern and Southeastern regions in India in the recent years. Analyzing weather data from 1951 to 2015 to understand the incidence and duration of heatwave conditions in India, the study found that the average heat wave duration in the Northwestern and Southeastern regions of India has increased during this period. 

However, the average duration of hot days has decreased over most parts of India from 1951 to 2015, except in the northwest and southeast regions. According to the researchers, this may be due to the increase in average heatwave duration in the Northwestern and Southeastern regions during the same period as hot days could be upgraded to the heatwave category as temperature soars.

 

Fish fauna in Bharathapuzha under severe threats, warn scientists

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A view of Bharathapuzha (Image Credit: Wiki Media Commons/ Jjvellara)

Implement urgent conservation efforts or the rich and endemic fish wealth in the largest river in the Western Ghats of Kerala will remain only on papers, warns a new assessment on the threats to the fish diversity in the Bharathapuzha River, locally known as River Nila.

Through a survey on all the four major tributaries of the Bharathapuzha River system - Gayathripuzha, Chitturpuzha, Kalpathipuzha and Thoothapuzha – the study recorded 117 species of fishes in Nila with the highest species richness from the stretch between Parali to Purathur estuary. Among this, 33 are found only in Western Ghats and three are found only in Bharathapuzha River system. 

A group of researchers including A Bijukumar, Department of Aquatic Biology and Fisheries, University of Kerala, Siby Philip from Department of Zoology, Nirmalagiri College, Koothuparamba, Anvar Ali and Rajeev Raghavan from Conservation Research Group, St Albert’s College, Kochi and S Sushama from Department of Zoology, NSS College Ottapalam carried out the study which is published in the Journal of Threatened Taxa.

Top Ten Threats to River Nila

Despite the richness, the river system of River Nila is under threat from human interference, says the study which is published in the Journal of Threatened Taxa. “Several anthropogenic stressors including deforestation and loss of riparian cover, dams and other impoundments, pollution, sand mining, non-native species, climate change and destructive fishing practices are threatening the fish diversity of Bharathapuzha River system”, it says.

Threat #1: Sand mining

Most notorious, most widely known but most rampant, despite being regulated (encouraged ?) by the il-legal machinery. If we number the threat based on the calamity it brings, this one goes to top. The study marks the region between Pattambi and Thiunavaya as the superhot stretch of legal and illegal sand mining. Studies conducted by CESS in 1997 itself has shown that the rate of sand mining is way too above the rate of sand generation in Nila. For many fishes in Nila, Sand is the breeding substrate, and is the single crucial link that supports the aquatic food web. With the indiscriminate sand mining, it is just a matter of time for fishes like Glossogobius giuris and Sicyopterus griseus to vanish from Nila forever, warns the study.

Threat #2: Dams and impoundments

Known fact: Big dams are a major threat to the rich and endemic fish diversity of Nila, since they change the turbulence of the river causing high sedimentation and other problems. Lesser Known fact: Dozens of smaller check damk dams across Nila are also doing the same. Bigger dams are fixed in number so far – Nila has 11 irrigation dams. Impoundments are still proliferating, turning out to be a lesser noticed diversity killer in Nila. It has severely affected the movement of certain fish species and is believed to be a reason for the near absence of eels in the river system.

Threat #3: Pesticide pollution

When it comes to a River system like Nila, don’t think it is just the factories that are pushing chemicals to the water. River basin dependent extensive agriculture and plantations are also contributing their fair share to polluting this blood line of middle Kerala. Chemical fertilizers, pesticides, chemical nutrients, weedicides, you name it. The resulting eutrophication- the facilitation of aquatic plant growth which in turn decreases the available oxygen in the water, killing the aquatic fauna- is a major issue, especially from Chamravattom to Purakkad, says the study.

Threat #4: Urban sewage

Read Pattambi. According to the study, the town of Pattambi which falls under the Palakkad District of the state of Kerala is a major source of urban sewage which pollutes the river extensively, taking over the pollutant cocktail made by the agro-pollutants. “The urban sewage canals directly open into the river, through which the municipal waste is dumped. Such large scale pollution not only degrades the habitat but also causes endocrine disruptions and several other physiological imbalances in fish including breeding failure which could ultimately lead to their extirpation”, says the study.

Threat #5: Deforestation

According to the study, deforestation in its catchment areas like Mangalam, Nelliyampathy, Walayar, Malampuzha, Nellipuzha, Dhoni and Kalladikode is a major threat. The loss of natural native vegetation has triggered the invasion by exotic plants. Not only that the fishes loose a food resource, the high sedimentation rate due to deforestation is changing the natural composition of the river bed. It makes survival difficult for many endemic loaches in the river since they use the pebbles in the river bed for breeding.

Threat #6: Lime stone mining

Lime stone mining is rampant in certain areas of the catchment of the river, says the study. This is especially prominent in Malampuzha, part of the Kalpathipuzha tributary. The study claims that the lime stone mining in the catchment areas is leading to pollution and siltation in the stream. Apart from triggering an unnatural rise in the silicate content in the water, the dumping of mining debris also damages smaller streams in the system like Seemanthinipuzha.

Threat #7: Alien species

The study has spotted at least six non-native fish species in Nila. While three of them were non-native to Indian rivers, three were from the Gangetic plains. Though the Indian major carps were introduced as part of aquaculture, considered as a success, the study was able to spot them from lower reaches of the river, revealing that they have proliferated though the river beyond their actual reservoirs. Such proliferation of non-native species often wipes out native species in the fight for resources. Species foreign to India like the Nile Tilapia and Mozambique Tilapia were also spotted from Nila, showing that the alien invasion is possibly stifling the endemic fish fauna of the river. However, the surprise factor was that the study reportedly failed to fetch another notorious alien species – African catfish- which is a known diversity killer in Western Ghats Rivers.

Threat #8: Climate change

Studies conducted in 2010 and 2011 discovered that the temperature in the Bharathapuzha basin has been on the rise for a 36 year period from 1969 to 2005. Moreover, rainfall data shows that the Nila watershed gets less rainfall than the state average. Though the temperature rise is often cited as an impact of climate change phenomenon and the increasing anthropogenic pressure in the river banks of the Nila, its effect on the biodiversity of the river system is scarcely studied.

Threat #9: Aquarium fish trade

 Comes in many colours –state supported as well as clandestine. This greed trade is especially wiping away endemic and beautiful fishes like Miss Kerala (Sahyadri denisoni) and Mesonoemacheilus remadevii, the latter being found only in river system in Silent Valley which is part of the Bharathapuzha River System. As per a recent study, Miss Kerala has been found to be collected in massive amounts from Thoothappuzha tributary for pet trade.

Threat #10: Destructive fishing practices

Last, but not the least, as always. Poisoning, use of mesh nets and dynamiting – small effort, good catch. Though traditional fishermen abstain from practices like dynamiting, it is raising a major threat to the fish diversity in the tributaries where the traditional fishermen are lesser in number, warns the study.

Action Time: Conservation Points to save Nila

• Prioritizing integrated watershed programmes.
• No more new medium or big dams, cautious about new check dam proposals.
• Channelize district River Management Fund to Eco restoration of stretches of Nila.
• Regulation of sand mining has been proved to be futile. So finding an eco-friendly alternative to sand is the only option left. But that will be like legalizing marijuana- you have to first convince the cartels before you convince the government. (They will have to take it, since the sand is running out and the weed is on the rise).
• Beg people not to use pesticides or agro-chemicals near the river bed cultivations (otherwise also).
• Regulate large scale riverbed cultivation.
• Establishing Aquatic Biodiversity Management Zones (ABMZ) to conserve river stretches known to shelter endemic and rare fishes.
• Regulate the greed pet trade and destructive fishing practices, not to say dynamiting.
• Above all, let people know – ask them, request them, beg them, threaten them – You may go the extreme since water is the life blood of the green earth, as River Nila is for Kerala.

One third of the coral reefs in the world will suffer degradation by 2030 due to climate change

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According to a new study on climate change and its effects,  a group of scientists have found that the chances of saving world’s coral reef population from the ill effects of climate change is thinning day by day as the greenhouse emissions are increasing.

Great Barrier Reef
Image courtesy:  Richard Ling

The danger to coral reefs is almost impossible to be averted, indicates the study which is published in the journal Nature Climate Change. One third of the coral reefs in the world will suffer long term degradation due to climate change by 2030, finds the study even though the estimation is based on the most optimistic IPCC estimations on emissions.

“One-third (9–60%, 68% uncertainty range) of the world’s coral reefs are projected to be subject to long-term degradation under the most optimistic new IPCC emissions scenario, RCP3-PD.”, says the study

"The window of opportunity to preserve the majority of coral reefs, part of the world's natural heritage, is small," said Malte Meinshausen, a co-author of the paper to Reuters news agency. This will happen even if the emission cuts are made stricter, shows the study.

Bleaching and decalcification of corals

The scientists have assessed the impact of emissions on 2160 coral reefs in different parts of the globe, with the help of climate models. The study points out that the emission of Carbon dioxide, a greenhouse gas, has increased by more than 3 percent last year. As a result, the average temperature of the globe has also increased by 0.8 degree Celsius approximately, during the last century.

The increasing global temperature and warmer oceans will bleach the corals to death. Thus, the reefs turn pale when the warm sea surface triggers mass bleaching events across the globe, says the study.

Even if the corals survive the ill effects of bleaching, it is difficult for them to survive a prolonged period of heating up of the ocean. According to the study, when the oceans stayed hot for a prolonged period during 1998, 16 percent of corals vanished from the face of earth.

Acidification is more fatal to the survival of corals than the bleaching events. Acidification of ocean is directly proportional to the presence of Carbon dioxide in the ocean surface. With the acidification increasing, the rate of calcification - a process which is crucial to the existence of corals - gets disrupted, leaving them to corrode to death.

Location of Corals in the world

2 degree Celsius limit is no safer zone for corals

The study also points out that the present notions of safe emission levels and safe temperature rise levels may not save coral reefs. 2 degree Celsius is widely considered as a safe emission limit to avoid the devastating effects like droughts, sea level rise or failure of cultivation. However, it will not help corals to avoid the serious threats of global warming, shows the study.

According to the scientists, the chances of survival for at least half of the coral reefs in the world will remain live only if the average mean temperature rise stay below 1.2 degrees compared to that of pre-industrial period.  

Though the reefs’ ability to adapt and evolve with changing quality of the habitat may make a difference in their survival to the acidification and bleaching events. However, their ability to adapt significantly within a matter of decades (which is a very small period for evolutionary processes), in an atmosphere of continuously changing ocean temperatures is still uncertain.

Moreover, the rate and magnitude of warming, which the globe is going to face, has no equals in the past, points out the scientists. They are doubtless that the prominence of coral reefs in coastal ecosystems will plummet, if the global mean temperatures exceed 2 degree Celsius above that of the pre-industrial era. 

Climate change to badly affect bat life, says new research review

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Climate change is speculated to affect almost all living creatures on the earth. Some will be severely hit due to their close relation to the climatic conditions of their habitat while some other may adapt and survive these changes. Bats, however, make it to the first category, points out a new review published by the journal Mammal Review.

According to the study, changing climate pattern is already taking its toll on many bat species. Based on a review of existing empirical data on the impact of climate change on bats, the scientists point out the bats are yet to face worst things. 

Indian Flying Fox (Pteropus giganteus),
Image Courtesy: Wikimedia Commons

"Climate influences the biogeography of bats, their access to food, timing of hibernation, reproduction and development, frequency and duration of torpor and rate of energy expenditure", says the study. 

Analysing the data on the foraging, roosting, reproduction and biogeography of bats, in relation with extreme weather events and indirect effects of climate change, the review finds seven risk factors associated with bats as a result of climate change.

Bat risk factors in a changing climate

Bats distributed in geographically smaller ranges and high altitude and latitude ranges will be severely affected since climate change will leave them with no other home to move on. Bats which are distributed in the areas which may come under water stress as a result of changing climatic conditions also will be victimised.

However, their eating habits also will risk certain types of bats. For example, aerial hawking bats which live on an insect diet will have to travel more to find food. Similarly, since they lack body adaptations to prevent water loss, they will have to fly more to quench thirst when the climate gets warmer. This will adversely affect feeding mothers more, points out the study.

The hibernation patterns will also be changed. Bats which are known to undergo torpor or temporary hibernation periods with minimal physiological activity to conserve energy will have to wake up from it earlier than usual, in warmer conditions. It may jumble up their energy conservation tactics.

The reproduction pattern may change, but need not be in negative direction, says the study. Though there is a lack of enough data to assess the impact on reproduction, the researchers think that a warmer climate may help females to give birth and grow their child earlier than usual.

Threatened bats species under risk

The study has used the case of European and north-west African bats to identify the risk associated with climate change. It finds that 38 out of 47 species among these bats will be affected by climate change. Among them, 11 species which live on tress or caves will be severely hit, says the study.

All these bat species are presently categorized as endangered, critically endangered or vulnerable by IUCN. So their status is less likely to improve with the climate change, suggest the study.

Read more on our coverage on climate change 
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Climate change will bring unprecedented marine life extinction in near future, says scientists

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As the impact of a gradually growing climate change is secretly creeping into our life, a group of leading scientists point out that it is the marine life on earth that will be hard hit with maximum number extinctions due to climate change. As per a review published in the Trends in Ecology and Evolution Journal, the climate change will cause unprecedented levels of mass extinctions in marine life.

Map showing that the Earth is getting warmer
Note: Image not relted to the reserach mentioned in the report
Image courtesy: Wikimedia commons

By analyzing the causes and patterns of marine extinctions and extinction risks with the help of fossil, historical and modern records, the paper argues that many periods in the past had similar climatic conditions estimated to take place in the future. Apparently, the effects also could be the same. 

“Even if the ultimate drivers of extinctions have changed over time, the proximal effects experienced by organisms might be similar”, says the paper. 

For instance, the increase in atmospheric CO₂ in the Permian era was due to volcanic activity but now it is caused by the burning of fossil fuels. Both ways, it has taken the toll on the marine organisms. However, it makes the extinction rates in the Permian era a better indicator to that in the immediate future. 

Lessons from the past

By analyzing geo chemical data and fossil records in the past, the researchers have found that three among the five largest extinctions in the past were related to global warming and ocean acidification. Similarly, the study has also found that loss of oxygen, habitat loss due to human intervention and pollution have also contributed to large scale extinction rates in the past. 

History of carbon dioxide concentrations
Note: Image not relted to the reserach mentioned in the report
Image courtesy: Wikimedia commons

Based on the lessons they learned by joining the jigsaws of data from fossil, historic and modern records, the study estimates that the marine organisms with a restricted geographical range will be more prone to extinction risk from habitat loss due to climate change. 

“As such, extinction risk in the future might shift from larger-bodied species to those with restricted geographic ranges as marine ecosystems respond increasingly to habitat loss and the environmental disturbances associated with climate change.” says the study.

Though over-exploitation and habitat loss were major reasons for extinctions in the past, acidification and warming will become more important drivers of extinction in the present times, despite cases of over-exploitation still existing, says the review. 

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Read more on our coverage on climate change

Shifting phytoplankton diversity at Sunderbans is an early sign of climate change

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Researchers in India has found a low abundance of a temperature sensitive phytoplankton Ceratium symmetricum at the estuaries and offshore of Sunderbans Biosphere Reserve. The change, which is triggered by the rise in the temperature of the surface water can be an early sign of climate change affecting the mangrove ecosystem of Sunderbans, says the study.

Ceratium symmetricum
Photo Courtsey: JOTT

Phytoplankton are minute photosynthetic aquatic organism floating on the water surface as a green discoloration of the water surface. Being primary producers, they are the foundation of a marine food web by offering food to fishes and other aquatic organisms.

The study which is the first one to examine the phytoplankton diversity in the Indian side of the Sunderbans, has assessed the presence of genus Ceratium Schrank in connection with physicochemical parameters such as Sea Surface Temperature (SST) in the estuaries of the Hooghly and Ichamati-Raymongal Rivers on the western parts of the Sunderbans.

Phytoplankton as bio-indicators

Phytoplanktons are known for their bio-indicator capabilities since any slight change in water temperature or the environment make big difference in their abundance. Members of Ceratium genus are especially known for their sensitivity towards temperature.

The research team has identified 5 species of phytoplankton from the genus - Ceratium trichoceros, Ceratium symmetricum, Ceratium fusus, Ceratium tripos and Ceratium furca- from the water samples. Among them, Ceratium symmetricum was not reported from the area earlier and was found in low abundance. According to earlier studies, low abundance of certain Ceratium species in the surface water during warm period is a sign of change.

To find out a possible cause for it, the researchers have studied the fluctuation pattern of the Sea Surface Temperature with the help of satellite imagery form 2003 to 2009. The data showed that the winter SST has been showing a rising trend in the area, possibly due to climate change.

  

Future Impact

 The lower abundance of Ceratium symmetricum and the rising trend in the winter SST are indicators of climate change affecting Sunderbans, says the study which is published in the latest issue of Journal of Threatened Taxa. It also points out that a further rise in the SST in the area may wipe the Ceratium symmetricum away from the Indian part of the Sunderbans, making it the first organism to take the toll of the climate change and the resulting temperature rise.

Anirban Akhand, Anirban Mukhopadhyay, Pranabes Sanyal and Sugata Hazra from the School of Oceanographic Studies, Jadavpur University, Sourav Maity, Indian National Centre for Ocean Information Services (INCOIS), Indrani Das, Department of Botany, Midnapore College took part in the study.

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