At least 361 people dead following series of landslides in Kerala State, India.

At least 361 people have lost their lives, with another 206 still missing and more than 273 having suffered injuries, following a series of landslides in the Wayanad District of Kerala State on 30 July 2024. The landslides occurred when heavy rains associated with the onset of the onset of the annual monsoon. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall. The landslides have affected the villages of Punjri Matom, Mundakkai, Chooralmala, Attamala, Meppadi and Kunhome.

Rescue workers searching for survivors following a landslide in Wayanad District, Kerala, on 30 July 2024. Times of India.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season, the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate.

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

Wayanad District is thought likely to have become more vulnerable to landslides due to the extensive deforestation it has suffered in recent years. Tree roots can help to hold soft sediments together on slopes, and deforestation is often associated with landslides. According to a 2022 study led by Kakoli Saha of the School of Planning and Architecture, Bhopal, between 1950 and 2018 Wayanad District lost around 62% of its forest cover, mostly being replaced with tea plantations, which have much shallower root systems, failing to stabilise steep slopes.

Land use land cover change of Wayanad District from 1950 to 2012; (A) land use land cover till 1950; (B) land use land cover till 1982; and (C) land use land cover till 2012. Saha et al. (2022).

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Cigaritis meghamalaiensis: A new species of Lycaenid Butterfly from the southern Western Ghats of India.

Lycaenid Butterflies or 'Blues' are a widespread and highly successful group of Lepidopteran Insects, noted for their blue or metallic colouring. With about 6000 known species, Lycaenids are found on all continents and comprise about 30% of all described Butterfly species. The group is particularly notable for its relationship with Ants, with the females of many species laying their eggs in or near to Ant nests, and the young of many species being able to induce the Ants to feed them while they mature within the nest. This relationship appears to have mutualistic roots, with some members of the group having larvae which are guarded by the Ants while they feed, and which produce a sugar-rich honeydew which the Ants consume. Silverlines, Cigaritis spp., are a genus of Lycaenid Butterflies found across Africa, South and Southeast Asia.

In a paper published in the journal Entomon on 31 December 2023,  Ramasamy Kamaya Naicker of  Saptur Palace and the Vanam Trust, Sujitha Prabhakaran Chandrika of the Department of Zoology at the University of Kerala, Baiju Kochunarayanan of Sreerangam, Jebine Jose of Kaduvathookil House, Manoj Kripakaran of Shyladhri, Rajkumar Chidambaram Palaniappan, also of the Vanam Trust, Vinayan Padmanabhan Nair of Nethaji Housing Colony, Kalesh Sadasivan of Greeshmam and the Travancore Nature History Society describe a new species of Cigaritis from the southern Western Ghats of India.

The new species is named Cigaritis meghamalaiensis, where 'meghamalaiensis' means 'from Meghamalai' , in reference to the region where it was discovered; the name 'Meghamalai' means 'cloud mountain', so the name also refers to the subtropical montane cloud forests where the species is found. The species was first observed at high elevations within the Periyar Tiger Reserve in Kerala State, and subsequently also found in the adjoining Meghamalai Mountain Range of Tamil Nadu.

Cigaritis meghamalaiensis Field images of males, females and seasonal forms. (A) Male, typical colouration; (B( female, typical colouration; (C) male upperside; (D) female upperside; (E) dry season male underside; (F) dry season female underside; (G) mating; (H) oviposition. Ramasamy Naicker in Naicker et al. (2023).

Males of Cigaritis meghamalaiensis have forewings that are black on the upper side with extensive metallic blue markings, and hindwings that are grey with blue markings. In females the forewings are grey with metallic blue markings and the hindwings are a lighter grey with blue markings. In both sexes the undersides of the wings in both sexes are a pale pinkish brown with pinkish orange markings.

Cigaritis meghamalaiensis. Early stages, larval pens, and attending Ants. (A) Freshly laid egg; (B) larvae being attended by Crematogaster Ants inside the larval pen; (C) intermediate instar larvae and its attending Ant; (D) larval pen under the bark of a shola tree opened to reveal the walls (white arrows), and two larvae inside it marked 1 and 2  (blue arrows). Kalesh Sadasivan & Jebin Jose in Naicker et al. (2023).

Butterflies were observed flying between December and June, although they were surprisingly reluctant to the wing, making them easy prey to Spiney Lizards and other predators. They were found only on the fringes of subtropical evergreen forests. Females were observed to fly around trees with populations of predatory Acrobat Ants, Crematogaster spp.. Mating was observed in April, and eggs were laid between April and December, on the bark of trees and shrubs such as Neolitsea spp. and  Clerodendrum infortunatum, always in the presence of Crematogaster wroughtonii Ants, either in dark crevices on the stems or directly in the Ants' nests.

Cigaritis meghamalaiensis, habitat and host plants. (A) Sub-tropical Evergreen forests of Meghamalais (1400m above sealevel); (B) Neolitsea cassia, a host tree; (C) typical climate inside the misty cloud forests; (D) female ovipositing inside Crematogaster nest on Clerodendrum infortunatum. Ramasamy Naicker, Kalesh Sadasivan, & Jebin Jose in Naicker et al. (2023).

Larvae were observed in 'pens' under the bark of the trees, where they were tended by Crematogaster wroughtonii Ants. These pens each contained 3-4 larvae, and appeared to be constructed specifically by the Ants, away from their own nests. This suggests that the relationship is mutual rather than parasitic, with the Ants gaining some benefit from the relationship, possibly consuming some product produced by the caterpillars. 

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'Killer' Elephant relocated in Kerala.

An Elephant alleged to have killed a number of people in Kerala State, India, has been relocated to a Tiger reserve away from Human populations. The Elephant, a 36-year-old male named Arikomban, is claimed to have killed seven people during raids on Rice stores in the area around Devikulam Forest in Idukki District, although this has been disputed People for Animals, an Indian Animal welfare organization, who claim their investigations have been unable to find any instances of people being directly harmed by the Elephant. What is not disputed, however, is that Arikomban is a notorious Rice-thief, and while he was able to take Rice from older Bamboo-and-Grass stores without causing much damage, as concrete and other modern building materials have become more common, the Elephant has been increasingly causing damage to property during his raids, fueling conflict with local Human populations, who have been petitioning the Kerala Forest Department to have him relocated.

The Elephant, Arikomban, being relocated on Saturday 29 April 2023. Arun Chandrabose/BBC.

Arikomban has been living around Humans since 1987, when he was a calf and his mother sustained a leg injury and was looked after by villagers near Chinnakkanal, before eventually perishing. Since that time he has tended to live around Humans, and had few interactions with other Elephants. This has included raiding Rice stores for food, something which was for a long time tolerated, but which has become more of an issue over time as the Human population has grown, a problem which has been repeated across India in recent years, where 30 000 wild Asian Elephants (60% of the global total) now co-exist with 1.4 billion Humans (18% of the global total).

Arikomban foraging on a Tea estate in Idukki District, prior to his capture. New Indian Express.

The Kerala Forest department initially applied to the Kerala High Court for permission to take Arikomban into captivity, but this was rejected following opposition from Animal welfare groups. A plan was then devised to move the Elephant to the Parambikulam Tiger Reserve, about 175 km from the area where he has been living, but this was opposed by people living close to the reserve, who were alarmed by Arikomban's reputation. Following this, it was decided to relocate the Elephant to the Periyar Tiger Reserve, about 80 km from Arikomban's current home. Concerns were raised that the local Human population around Periyar might also reject Arikomban, but this appears not to have been the case, with large crowds turning out to great the Elephant as he was brought to the reserve. 

Crowds of well-wishers greeting Arikomban as he arrived at the Periyar Tiger Reserve. Manorama.

Arikomban is reported to have received a deep cut on the trunk during his capture, for which he was treated before being released. He was also fitted with a radio collar to monitor his progress. He was provided with several barrels of water laced with antibiotics for his wound, which were later found overturned, as well as several stores of food which it is hoped will help sustain him while he adapts to foraging in the wild. Tracking collar data has revealed that he was approached by a small herd of six local Elephants shortly after his release, but that these retreated without any apparent interaction.

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Landslide kills family of five in Kerala State, India.

Five members of a family have died after a landslide swept their house away in Kerala State, India, on Monday 29 August 2022. The incident happened in the village of Kudayathoor, in Idukki District, at about 4.15 am local time, following heavy rains overnight associated with the seasonal monsoon. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.  

Rescue workers recover the body of a woman who died when a landslide struck her family home in the village of Kudayathoor in Kerala State, India, on 29 August 2022. Reju Arnold/On Manorama.

The deceased have been identified as homeowner Chittadichaalil Soman, his mother Thankamma (74), his wife Shiji, their daughter Shima (25), and her son Devanand (4), with all the bodies recovered within five hours of the original incident. The area is still thought to be unstable, presenting a risk to nearby households, and local authorities are assessing the need to evacuate the entire community.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate.

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

Kerala has a complex seasonal cycle, driven by the presence of the Western Ghats mountain range, which largely block the dry northerly winds which dominate the climate of much of India, and its proximity to the equator, which leads to a double monsoon system. Such a double Monsoon Season is common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices, making the solstices the coolest part of the year and the equinoxes the hottest. In Kerala this results in a Southwest Monsoon, which lasts from May to September, and is driven by winds from the southern Arabian Sea dumping water onto the Western Ghats, followed by a Northwest Monsoon, which lasts from October to December, where winds from the Bay of Bengal do the same. Of the two monsoons, the southwest is the wetter, due to the proximity of the sea, with June typically being the wettest month, with an average of 341 mm of rain falling in the month

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Two dead in Kerala as Cyclone Tauktae moves up the west coast of India.

Two people have died in Kerala State, India, as Cyclone Tauktae moved up the western Indian coast over the past two days, bringing with it high winds, heavy rainfall, and storm surges. The storm has caused widespread disruption, flooding low lying areas, uprooting trees and downing power lines, but has so far caused relatively few casualties to the evacuation of thousands of people from areas expected to be the worst hit (before the introduction of this practice, tropical storms making landfall in India regularly killed thousands of people). So far the storm has passed along the shores of Tamil Nadu and Kerala states, and is expected to pass Goa and move on to Maharashtra today, eventually making landfall in Gujarat on Tuesday 18 May 2021.

 

A storm surge near Mangaluru, in Karnataka State, India, on Saturday 15 May 2021. Press Trust of India.

Tropical storms, called Cyclones in the Indian Ocean and South Pacific, are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere. These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

 

A rescue team carries a woman from a flooded building in Kochi, Kerala, on Saturday 15 May 2021. NDTV.

Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms.

 

The path and strength of Cyclone Tauktae. Thick line indicates the past path of the storm (till 6.00 am GMT on Sunday 16 May 2021), while the thin line indicates the predicted future path of the storm, and the dotted circles the margin of error 12, 24, 36, 48 and 72 hours ahead. Colour indicated the severity of the storm. Tropical Storm Risk.

 

The formation and impact of a storm surge. eSchoolToday.

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Surveying the Brachyuran Mangrove Crabs of Kerala State, India.

Brachyurans are the most prominent group of Crabs, because of their great diversity; comprising of about 6793 species, 1721 genera, and 93 families recorded globally. Brachyuran Crabs perform a significant role in the Mangrove ecosystems and are commercially valuable with high culture and fattening potential. Mangrove ecosystems warrant more attention as it is diminishing day by day, especially along Kerala coastline and its importance protecting the environment from natural catastrophes are increasing. Mangroves are fragile ecosystem having highly variable conditions of life style, which make them profusely rich in biodiversity. The ecosystem value of Mangroves overwhelms any other ecosystem as it gives very many services, including biodiversity richness. Distribution studies of Brachyuran Crabs, especially the Mangrove Crab in Indian Mangroves are scanty and the available literature generally discusses the distribution of both marine and estuarine/Mangrove Crabs together.

Literature regarding Crabs of Mangrove ecosystems of Kerala was comparatively meager apart from that of few individual report and citations of each Crab species. In 2008 Muthiah Kathirvel reported 990 species of marine Brachyuran Crabs belonging to 281 genera and 36 families from Indian waters. Thirty-six Brachyuran Crab species were identified from Pichavaram Mangroves by another study in 2008. Another study in 2013 revealed that 33 Mangrove Crab species belonging to the family Grapsidae and Ocypodidae were found in the state of Tamil Nadu. A comprehensive approach to document the diversity and abundance of true Mangrove Crabs is lacking especially fromvKerala, which is considered to be one of the Crab-rich states.

In a paper published in the Journal of Threatened Taxa on 26 November 2020, Kurian Mathew Abraham and Apreshgi Kolothuthara Prakasan of the Department of Aquatic Biology and Fisheries at the University of Kerala present the results of a study which aimed to create a check list of the Brachyuran Crabs  of the Mangroves of Kerala, and photo-document that diversity, along with revalidation of Crab nomenclature.

 

A survey of Crabs of different estuarine mangrove ecosystems along the western coastline of Kerala was carried out from June 2016 to May 2017. Crabs were collected live by handpicking, opening of burrows, bait trap and normal traditional trap kept overnight.

 

 

The sampling locations of mangrove crabs from Kerala. Abraham & Prakasan (2020).

 

A total of 18 species of true Mangrove Crabs under four families (Portunidae, Grapsidae, Sesarmidae, and Ocypodidae) and 11 genera were identified and documented in the present study. Highest number species was recorded from the family Sesarmidae (seven species) followed by Portunidae and Ocypodidae with four species each and Grapsidae with three species. Scylla serrata, Scylla olivacea, and Thalamita crenata were the economically valuable crab species. Parasesarma bengalense was reported for the first time from the western coast of India and Clistocoeloma lanatum was reported for the first time from Kerala Mangroves. Pseudosesarma glabrum was one of the rarer species and was recently reported from Cochin in southwestern India. Parasesarma plicatum was the most common Crab species encountered throughout west coastline Mangrove ecosystems of Kerala.

 

Checklist of Mangrove Brachyuran Crabs from Kerala. Abraham & Prakasan (2020).

Studiess in the 1950s reported the occurrence of Crabs from Mangrove habitats around Travancore and Bombay respectively without much of its taxonomic identity. After a long gap, a 1980s study reported the presence of 20 species of Crabs from Pichavaram Mangroves, which includes true Mangrove as well as estuarine Crabs. There are several taxonomic works on the Brachyuran Crabs of estuarine and Mangrove ecosystems of India. A total of 55 species of Brachyuran Crabs represented under 31 genera have been reported earlier from different Mangrove habitats of India. But none of the above reports exclusively documented Mangrove Crabs, in fact they included estuarine, marine forms in addition to Mangrove Crabs. Eighteen species of Brachyuran Crabs under nine genera and four families were identified exclusively from Sunderban Mangrove ecosystems. A study of the Mangrove fauna of the Andaman & Nicobar Islands listed 31 species of Crabs from Andaman Mangroves and briefly dealt with zonation and annual breeding pattern of some of the Crabs.

 

Mangrove Brachyuran Crabs from Kerala. Abraham & Prakasan (2020).

The nomenclature of many Crabs has been changed by different taxonomists, with the genus name of four Crabs has been changed or revalidated recently; Perisesarma bengalense has been changed to Parasesrma, the genus Uca has been renamed as Austruca for Uca annulipes and Uca perplexa and Uca vocans has been renamed as Gelasimus vocans. Many taxa belonging to the genus Perisesarma have been changed to Parasesarma, however, Perisesarma dussumieri, without any name changes is the type species of the genus Perisesarma owing to its original characters of the genus. All the Crabs by Abraham and Prakasan are listed as ‘Least Concern’ status on the International Union for the Conservation of Nature's Red List of Threatened Species, which may be due to lack of baseline data about abundance and distribution the true Mangrove Crabs.

 

Mangrove Brachyuran Crabs from Kerala. Abraham & Prakasan (2020).

Abraham and Prakasan's investigation revealed 18 true Brachyuran Mangrove Crab species along estuarine mangroves of western coast of Kerala. Family Sesarmidae constitute the major diversity (seven species) followed by Portunidae (four species) and Ocypodidae (four species), and least in Grapsidae (three species) of Mangrove Crabs. Among the 18 Brachyuran Crabs, four crabs have been revalidated by change in genus or species name and provided in a checklist along with photo-documention of true Mangrove crabs of Kerala estuarine systems.

 

Mangrove Brachyuran Crabs from Kerala. Abraham & Prakasan (2020).

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