Climate change hastens extinction of ‘pawikan’

By Jonathan L. Mayuga

 

Published in the Business Mirror, May 31, 2016 

http://www.businessmirror.com.ph/climate-change-hastens-extinction-of-pawikan/

 

Pawikan DENR-Strategic Communication and Initiatives Service

Climate change is partly being blamed for the dwindling global population of marine turtles.  Conservation experts in the Turtle Islands Wildlife Sanctuary (TIWS) suggest that the problem could be worse.

They said El Niño and beach erosion caused by climate change-triggered effects, such as sea-level rise and storm surges because of the intensifying typhoons, might hasten the extinction of these mysterious creatures of the sea.

The downtrend in the number of nesting marine turtles and eggs in the TIWS has been observed over the past decade by the Department of Environment and Natural Resources-Biodiversity Management Bureau (DENR-BMB) working under Pawikan Conservation Program (PCP) on Turtle Islands, Tawi Tawi.

Aggravating rampant illegal wildlife trade that targets pawikan and the human habitation of beachfronts are the longer hot season, an effect of El Niño and beach erosion, which destroys marine turtle’s nesting grounds.

Experts said it has become extremely hard for these mariners of the sea to dig a pit for their eggs.

One theory is the long dry season, which makes the sand in beaches dryer and harder to dig a pit. Another theory is erosion, which causes beaches to shrink, leaving pawikan no choice but to instinctively scale up and move farther away from the ocean where the sand covering the soil is thinner and much harder for the pawikan to dig.

Whichever is the case, the country’s top biodiversity official said there is a need to validate these theories, particularly at the TIWS, to address the problem.

“We have to validate and know the extent of the effect to beaches caused by El Niño. But what we know is that beach erosion exposes the soil underneath the sand that is harder and more difficult for turtles to dig a pit for their eggs,” Theresa Mundita Lim, director of DENR-BMB, told the BusinessMirror in an interview on Wednesday.

‘Pawikan’ sanctuary

Composed of six islands, Turtle Islands is a municipality in Tawi-Tawi. It was declared as a sanctuary for the endangered pawikan by virtue of Presidential Proclamation 171 on August 26, 1999, creating the TIWS under the National Integrated Protected Areas System (Nipas) Act.

TIWS covers an area of 138,357 hectares, which constitute of six islands, namely, Boan, Lihiman, Great Bakkungan, Langaan, Taganak and Baguan. As a wildlife sanctuary, the entire town is basically reserved for the conservation of the endangered pawikan, a migratory marine species believed to have existed for millions of years, along with the dinosaurs.

TIWS is part of the bigger Philippine-Sabah Turtle Islands Heritage Protected Area (TIHPA), which was forged through a historic bilateral agreement between the Philippines and Malaysia, creating the first and only trans-frontier protected area for marine turtles in the world. TIHPA is one of the biggest pawikan sanctuaries in the world.

TIHPA is composed of a total of nine islands for the purpose of conserving pawikan, three of which are in nearby Malaysia.

The management of the TIHPA is shared by both countries, making possible the conservation of habitats and sea turtles over a large area independent of their territorial boundaries.

Two of the six islands—Buan Island and Great Bakkungan Island—have been stricken out of the list of nesting sites being monitored by the DENR-BMB because of human encroachment of beach fronts causing pawikans to lay their eggs elsewhere.

Not exclusive for ‘pawikan’

The TIWS as a sanctuary, according to the DENR-BMB, is not exclusively for the conservation of pawikan. A profile of the TWIS indicates the area is rich in terrestrial and marine flora and fauna.

Turtle Islands supports a diverse population of marine fauna of corals and fishes, as well as two species of endangered marine turtles. TIWS exhibited the highest diversity in terms of marine communities among all Nipas sites in the country.

Two species of endangered marine turtles are found in Turtle Islands. Eighty percent of the country’s remaining marine turtle resource is found in the area.

Turtle Islands is regarded as the only major nesting ground, with more than 1,000 nesters of green turtle (Chelonia mydas) annually in the Asean Region. There are only 10 remaining nesting sites worldwide.

The hawksbill (Eretmochelys imbricata) also occur on the islands, but with a low density in nesting in contrast to the green turtle.

Worldwide, marine turtle population have critically declined, hence, the Convention on International Trade in Endangered Species of Wild Fauna and Flora and International Union for Conservation of Nature and Natural Resources has declared all species of marine turtles as endangered.

Other wildlife

The coastline of Baguan Island, according to a biological profile prepared by the DENR-BMB revealed that its coastline is encroached with tropical trees, such as tropical almond and coconut, and many others.

Around 50 seaweeds species were also recorded in the area, which represents 32 percent of the 158 of macrobenthic seaweeds identified from 18 coastal province in the country.

Of the 50 species identified, 23 species are of class of green algae, four species of brown algae and 23 species of red algae.

In terms of diversity, Baguan Island exhibits a significant difference in comparison to the other islands by possessing 47 species of seaweeds compared to Langaan and Taganak with only 25 and 20 species, respectively, according to the DENR-BMB.

The islands composing the TIWS are also inhabited by endangered reptiles, such as the monitor lizard, the natural predator of marine turtle eggs and hatchlings. Baguan Island is known to have more monitor lizards compared to the other islands.

There are two other species of lizard in the TIWS—the gecko and scincid.

Meanwhile, 12 species of birds were identified on Turtle Islands, two of which are endemic to the Turtle Islands, namely the Asian glossy starling and Treton v. vernans. In all islands, black rats, and fruit and insect bats were also observed.

 Cool chicks, hot dudes

According to Lim, scientific studies suggest that a marine turtle’s gender is influenced by the temperature of the nest—something pawikan conservation experts manning pawikan sanctuaries and hatcheries are concerned about with the advent of climate change.

“With warm temperature, it is likely that all eggs will develop into females. This will be a big problem if all hatchlings are all females,” Lim said.

Lim, who started her career in the DENR as one of the staff under Task Force Pawikan, which focuses on the conservation efforts on the Turtle Islands, said marine-turtle eggs are very delicate, too.

While an average of 80 percent of eggs laid actually hatch, very few of pawikan hatchlings may actually survive and become sexually mature to lay eggs and repopulate, a process which takes 30 to 40 years.

Causes of death

Scientists believe that effects of climate change to the population of pawikan have varying degrees.

At the TIWS, natural predation and climate-change effects, such as sea-level rise, storm surge and extreme heat adversely affect marine-turtle population.

“Storm surge and sea-level rise cause beach erosion. This means we are losing our nesting grounds for pawikan faster,” Lim said.

Also she said typhoons that trigger storm surge are known to destroy marine-turtle nests and exposure to saltwater causes plasmolysis, which destroys the eggs of pawikan. Accidents, such as falling with their back on the ground to lay eggs, also causes death because of direct exposure to sunlight. A pawikan can die within two hours because of extreme heat.

Another natural phenomenon, called sand switching, is a natural occurrence that shifts sand to other parts of an island or other islands, therefore, diminishing the nesting grounds of pawikan.

Too hot, too dry

Lately, protectors of TIWS, particularly its most-treasured pawikan, concluded that the number of nesting at the TIWS continues to decrease because of prolonged dry season, which is causing the sand in beaches to become stiff.

Minda Bairulla, TIWS Protected Areas Superintendent, in an e-mail message, told the BusinessMirror that from 2011 to 2015, pawikan nesting in the TIWS is decreasing.

“It has been observed that due to prolonged dry season, marine turtles were unable to nest because the sand is very dry and they find it hard to dig a pit to lay their eggs,” she said.

“Pawikan lays eggs all throughout the year but the peak are in the months of May, June and July. Around 30 to 50 nesting pawikan are observed to lay their eggs every night on the Turtle Islands,” she said.

In 2015 a total of 12,577 nesters were counted on the islands of Baguan, Langaan and Taganak.

From January to April this year, a total of 1,982 nesters were counted on Baguan and Langaan.

Beaches becoming dry and hard owing to El Niño is also occurring in other pawikan nesting grounds, which calls for the establishment of more marine turtle hatcheries.

With a pawikan nursery in place, the eggs are protected and released back to their natural habitat upon hatching.

Several hatcheries were created in select areas where many pawikan have been spotted to lay eggs.

Under normal circumstances, pawikan hatch from eggs on shore. Hatchlings struggle from their nesting ground to the beach.  It takes at least a decade for marine turtles to become sexually mature. Very little is known of how these hatchlings live in their natural habitat until they return decades later for their turn to lay eggs.

Using their fins, female marine turtles dig at least a foot deep to lay their eggs and cover them back with sand.

The incubation period range from 45 to 60 days, according to the DENR-BMB working under the Pawikan Conservation Program (PCP), which expanded the coverage of the Task Force Pawikan, from the Turtle Islands to the entire archipelago.

The effects of climate change due to longer dry season and hotter temperature increases the mortality of hatchlings during the incubation period, said Elsie Milana, a pawikan conservation expert who has a long experience in monitoring the behavior of the marine turtles during nesting at the TIWS.

She repeated earlier statements that the hot weather hardens the sand giving the pawikan difficulty to make their nest. Milana said as part of the conservation effort in the TIWS, after the pawikan succeeded in digging a pit and laying their eggs, the eggs are carefully transferred to pawikan hatcheries where they will be protected against natural predators, including people living in the islands who get the eggs for food.

Beach rehabilitation

According to Bairulla, the DENR office in Zamboanga Peninsula, which has jurisdiction over protected areas in the Autonomous Region in Muslim Mindanao, is eyeing to rehabilitate the eroded beaches.

It is also coordinating with law enforcement agencies to conduct monitoring and patrolling on the islands, which is reportedly being frequented by foreign fishing vessels targeting pawikan.

According to Lim, the DENR-BMB will compare old and new aerial photos of the islands within the TIWS to see if the beaches have really changed over the past years, and assess the extent of the potential damage caused by beach erosion.

She said the same investigation may be conducted in other areas that are known to host pawikan-nesting areas.

Meanwhile, Lim, cautioned against beach rehabilitation by resort developers to improve beaches using heavy equipment. The process involves hauling sands back to beaches, which may damage existing nests.

She also warned against building walls in beachfronts by some resort owners to prevent erosion, saying the process also prevents nesting pawikan from going to beaches to nest and lay their eggs.

“Beaches have natural defense against erosion, which happens because of extensive damage to coral reefs. What we need to do is look into the condition of the corals and rehabilitate these areas where the damage has been extensive. That way, we will have a natural defense against beach erosion,” she said.

She said during her last visit at TIWS early this month, she received reports of the extensive damage to corals caused by dynamite fishing and other destructive fishing methods. This alone, she said, should be addressed with the help of local government units.

Lim is planning to revive the plan to promote Turtle Islands for ecotourism, which will involve the help and support of concerned local government officials.

Tourism, she said, will boost conservation efforts on Turtle Islands as the people become involved and gainfully employed in ecotourism activities instead of illegal wildlife trade.