In Coral Skeletons, Microscopic Portraits of Resilience?

 

A scanning helium ion micrograph showing the process of crystal growth in coral. Credit Viacheslav Manichev and Stanislas Von Euw/Rutgers

Coral reefs are sprawling, intricate ecosystems that house an estimated 25 percent of all marine life and can sometimes be seen from space. Yet they are formed by a process invisible to us.

A study published in Science on Wednesday now presents a microscopic picture of the biology that makes corals’ skeletons grow. The findings suggest that coral may be more robust in the face of human-driven ocean acidification than commonly thought.

Corals grow their armor by diligently secreting a chunk of hard skeleton smaller than the width of a human hair each day. This process is called calcification and scientists have debated which parts of it are most important for decades.

One view prioritizes chemical interactions with the seawater. Using ion pumps, corals can possibly decrease the acidity of seawater enough that calcium carbonate — the stuff of limestone and chalk and the basis of coral skeletons — forms spontaneously. Under these circumstances, if oceans become more acidic — a potential consequence of human-emitted carbon dioxide in the atmosphere being absorbed by the seas — coral may struggle to form a skeleton.

The alternative view contends that calcification is primarily a biological process, coordinated by proteins similar to the ones that help us make our teeth and bones. The new study provides evidence for this perspective and some hope for corals in a world with more carbon.

“Coral is not just a rock,” said Paul Falkowski, a professor of marine sciences at Rutgers University and senior author of the study. “And because of that, we’re pretty confident that they’ll be able to continuing making their skeletons even if the ocean becomes slightly more acidic.”

Not all scientists agree.

“The problem is, we have lots of data that show many coral species are very sensitive to environmental change,” said Alexander Venn, a senior scientist at the Scientific Center of Monaco, who was not involved in the study. “While this paper builds a strong model for the biological control of calcification, there are still pieces of the puzzle missing.”

Dr. Falkowski and his colleagues used ultrahigh-resolution microscopic imaging and techniques for observing the structure of molecules to study skeletal branches from smooth cauliflower coral, a well-studied species common in the Indo-Pacific.

The result is a model of coral calcification that starts with a malleable form of calcium carbonate, called amorphous calcium carbonate.

The researchers say they believe that amorphous calcium carbonate is initially formed by proteins. Through a process not yet fully understood, little balls of the material then give way to aragonite, the form of calcium carbonate that makes up a mature coral skeleton.

Similar transitions have been observed in sea urchins and shellfish, and some scientists even suspect amorphous calcium carbonate may be a common precursor for calcification across the tree of life.

 

A scanning helium ion micrograph shows amorphous particles at the center surrounded by aragonite crystals. The transition from this first form of calcium carbonate to the second is not well understood. Credit Viacheslav Manichev and Stanislas Von Euw/Rutgers

“When we precipitate aragonite in the lab, just in a bucket of seawater, it forms this very characteristic pattern with very long, needle-shaped crystals,” said Nicola Allison, a lecturer in earth sciences at the University of St. Andrews, who did not participate in the research.

“This is the first report of amorphous calcium carbonate in coral, and it really does suggest the organism is able to control how solid material is deposited,” she added.

Alex Gagnon, an assistant professor of oceanography at the University of Washington who was not involved in the research, suggested it was an oversimplification to take seawater chemistry out of the equation. Acid dissolves calcium carbonate, so the more acidic the ocean is, the more difficult it is for corals to organize that first bit of skeleton.

“At the end of the day, the fundamental rules of chemistry and physics still apply,” he said.

It’s true that corals lose calcium carbonate in a more acidic environment — but they maintain the ability to grow back that skeleton, “which is good news,” Dr. Falkowski said.

Given current projections of ocean warming and acidification, he is more concerned about warming, which stresses the algae living inside corals and causes coral bleaching.

That said, Dr. Falkowski acknowledges that the cause of warming and acidification is one and the same: carbon emissions from fossil fuel burning. “For all intents and purposes, they’re linked,” he said.

Sumber : nytimes

Great Barrier Reef sharply declines in north but signs coral recovering elsewhere

Australian Institute of Marine Science says reef’s capacity to recover under threat from climate change and pollution

Parts of the Great Barrier Reef not regularly affected by problems such as cyclones have demonstrated the reef still has the ability to regenerate, with a survey showing sharp declines in coral cover in the north but increases elsewhere.
However, the latest results from the Australian Institute of Marine Science (Aims), collected by divers visiting 243 individual reefs, do not include the losses caused by bleaching this year, or the effects of cyclone Debbie, both of which killed coral in the central section.
Up until March 2017, the results show that coral cover over the whole Great Barrier Reef improved dramatically between 2012 and 2016 but then suffered an unprecedented loss from the 2016 bleaching, with about a quarter of the reef’s coral being killed.
The head of the long-term monitoring program at Aims, Hugh Sweatman, said the capacity of the reef to recover was under threat from climate change, as well as other chronic stressors such as pollution.
“The predictions under climate change are that cyclones will get more intense, which means there will be more damage, so they will require longer to recover,” Sweatman said. In addition, pollution and warmer waters are slowing the rate of recovery.

“So you’ve got this double whammy. The time for recovery is likely to get less and the rate of recovery is going to be impeded.
“So what I’m saying is it’s OK so far but there are limits to this.”
Sweatman also noted the recovery in the southern section of the Great Barrier Reef was partly a result of those reefs being mostly dominated by fast-growing corals, which are easily damaged by cyclones but recover relatively quickly.
Richard Leck, a campaigner at WWF, said the results gave hope to conservationists.
“There is still resilience in the system,” Leck said. “This data shows that if the reefs aren’t exposed to underwater heatwaves, if they’re not subject to major pollution events, and they’re not hit by a cyclone, then they recover really well and that should give us a lot of hope that the resilience of the Great Barrier Reef is still there and, if we reduce those threats, we should see recovery reef-wide.”

 Trends in mean hard coral cover for the whole Great Barrier Reef up until March 2017, from the Australian Institute of Marine Science’s long-term monitoring program. N indicates the number of reefs contributing to the analyses; blue shading represents 95% certainty. Photograph: Australian Institute of Marine Science 

That loss as a result of the 2016 bleaching event was driven almost entirely by coral mortality in the northern third of the Great Barrier Reef, where there was ongoing loss since 2013 caused by two cyclones and the continuing crown-of-thorns starfish outbreak.
As a result, the northern Great Barrier Reef has lost the majority of its coral, declining from about 25% coral cover in 2010 to just 10%. “This level of decline is unprecedented in the 30+ year time series,” the report said.

 

Trends in mean hard coral cover for the central Great Barrier Reef up until March 2017, from the Australian Institute of Marine Science’s long-term monitoring program. N indicates the number of reefs contributing to the analyses; blue shading represents 95% certainty. Photograph: Australian Institute of Marine Science 

Sweatman said next year’s results will likely reveal even more significant coral loss in that region, following the most recent bleaching and cyclone Debbie.
In the southern section of the Great Barrier Reef, the latest results show continued improvement in coral cover. In that region, coral cover had reduced from almost 45% coverage in the mid-1980s, to below 10% in 2011. The latest results show coral cover has continued to recover, to more than 30%.

 

Trends in mean hard coral cover for the Southern Great Barrier Reef up until March 2017, from the Australian Institute of Marine Science’s Long Term Monitoring Program. N indicates the number of reefs contributing to the analyses; blue shading represents 95% certainty. Photograph: Australian Institute of Marine Science  

The report notes that impacts from the latest bleaching will be captured in future Aims long-term monitoring program updates.
Imogen Zethoven, from the Australian Marine Conservation Society, said it was “heartening to see coral cover increase significantly in the southern third of the Great Barrier Reef”.
“It’s not too late to save our reef but the federal government must stop the Adani coalmine, reject all new coalmines and switch to 100% renewable energy as a matter of urgency,” Zethoven said.


Sumber : TheGuardian

38 Juta Potong Plastik Ditemukan di pulau Tak Berpenduduk di Selatan Pasifik

Pulau Henderson diperkirakan menyimpan 18 ton sampah plastik, merupakan rekor tertinggi di dunia dalam hal kepadatan sampah.

 

Daerah ini merupakan daerah paling terpencil di pasifik, merupakan atol yang tidak berpenduduk.  Sebanyak 99.8% dari polutan yang ditemukan adalah plastik.  Temuan ini merupakan bukti telah terjadi katastropik 

 

Peneliti dari Universitas Tasmania dan UK Royal Society for the Protection of Birds memperkirakan kepadatan mencapai 4,500 potong sampah/m2. 
Pada Februari, laporan peneliti menunjukkan level yang luar biasa pencemaran Palung Mariana, yang bersumber dari industri kimia dan plastik seluruh dunia.  Padahal Palung ini adalah tempat paling terpencil dan paling tidak dapat diakses di seluruh dunia.
Pada Konferensi Laut Dunia di awal Maret lalu, Indonesia berkomitmen untuk menganggarkan 1 juta USD untuk mengurangi sampah plastik dan polutan perairan lainnya, dengan target pengurangan 70% sampah perairan dalam waktu 8 tahun.

Laver, tim peneliti, mengatakan bahwa setiap individu dan pemerintahan harus berperan dalam pengurangan polutan plastik.  dia menekankan " Bagi saya, polusi plastik di laut adalah perubahan iklim baru, sehingga jangan sampai kesalahan yang sama terulang lagi.  Kita telah berdebat selama 40 tahun apakah perubahan iklim benar terjadi atau tidak.  Marilah tidak usah menunggu sains, tidak usah berdebat.  Jumlah plastik di perairan benar - benar fenomenal dan kita harus melakukan sesuatu sekarang"

Sumber : Guardian.com

KIP tolak permohonan membuka kajian reklamasi Teluk Jakarta

Upaya membuka naskah akademik kajian reklamasi di teluk Jakarta sementara kandas. Komisi Informasi Pusat (KIP) menolak gugatan sengketa informasi hasil komite gabungan reklamasi Teluk Jakarta yang dimohonkan Koalisi Selamatkan Teluk Jakarta.
Majelis komisioner menilai Kementerian Koordinator Bidang Kemaritiman sudah cukup akuntabel dengan memberikan daftar rekomendasi soal reklamasi Teluk Jakarta berupa presentasi melalui program komputer untuk presentasi powerpoint.
Ketua Majelis Komisioner, Evy Trisulo mengatakan Kementerian Koordinator Bidang Kemaritiman telah menjalankan kewajibannya dengan memberikan ringkasan dokumen rekomendasi. "Memutuskan, menolak permohonan informasi pemohon untuk seluruhnya," kata Evy Trisulo.
Meski menolak permohonan informasi, Evy menyatakan pendapat yang berbeda atau dissenting opinion. Ia menyatakan bahwa hanya beberapa dokumen yang mempunyai relevansi serta detail dokumen.

Dalam proses gugatan itu, Kementerian Koordinator Kemaritiman menyampaikan daftar rekomendasi soal reklamasi teluk Jakarta berupa powerpoint melalui surat elektronik. Adapun yang diminta Koalisi Selamatkan Teluk Jakarta adalah kajian komprehensif dari segi lingkungan, hukum, dan sosial, yang menjadi dasar kebijakan melanjutkan reklamasi.
Anggota majelis KIP Dyah Aryani mengatakan, Kemenko Kemaritiman sudah cukup kooperatif dalam menjalankan kewajibannya menyediakan informasi untuk masyarakat.
Koalisi Selamatkan Teluk Jakarta mengajukan gugatan tentang informasi kajian komite gabungan reklamasi sejak Agustus 2016 lalu. Ketika itu, Menko Maritim Luhut B. Pandjaitan belum menyatakan pada publik bahwa proyek reklamasi akan dilanjutkan. Padahal sebelumnya, mantan Menko Maritim Rizal Ramli menyatakan reklamasi dibatalkan.
Naskah akademik yang menjadi landasan Rizal Ramli itulah yang dicari Koalisi Selamatkan Teluk Jakarta. Alasannya, kalau itu dibuka, metode penelitian bisa dibandingkan sehingga diketahui penyebab mengapa dengan landasan kajian yang sama bisa keluar putusan berbeda.
Peneliti Indonesian Center for Environmental Law (ICEL) dan anggota Koalisi Selamatkan Teluk Jakarta, Rayhan Dudayev menduga hasil kajian terkait Teluk Jakarta tidak komprehensif dan tertutup. Menurutnya segala bentuk kajian atau dokumen yang menjadi kebijakan harus dipublikasikan.
"Kemungkinan kita akan menempuh upaya hukum berikutnya, karena dissenting opinion sudah jelas segala kajian yang menjadi landasan kebijakan harus disampaikan dan dipublikasikan," ujar Rayhan.
Rayhan mengatakan publik masih bertanya-tanya, apakah kajian tersebut dibuat secara obyektif atau tidak. Ia mengatakan, alasan mengajukan permohonan informasi adalah ingin mempelajari dan mengetahui hasil kajian komite gabungan reklamasi Teluk Jakarta yang diperintahkan oleh Presiden Jokowi sebagai bahan kajian dari perspektif hukum lingkungan hidup.
Anggota koalisi Marthin Hadiwinata mengatakan, kajian yang disengketakan itu merupakan dokumen yang menjadi dasar kebijakan Kementerian Koordinator Bidang Kemaritiman dan publik berhak mengetahuinya. Ketua Pengembangan Hukum dan Pengembangan Nelayan KNTI ini mengatakan, koalisi akan menunggu salinan putusan tersebut, sebelum akhirnya mengajukan banding ke Pengadilan Tata Usaha Negara.
"Kami menyatakan kecewa terhadap keputusan ini. Kekecewaan ini karena apa yang kami inginkan, kami mohonkan informasinya adalah informasi yang menjadi dasar bagi pemerintah melakukan rekomendasi tersebut," kata Marthin.

sumber : beritagar.id

Audit Lingkungan Bukan Untuk Meneruskan Reklamasi Kata Tim Sinkronisasi

Anggota tim sinkronisasi Anies Baswedan - Sandiaga Uno Marco Kusumawijaya mengatakan pihaknya tetap tegas menolak proyek reklamasi di Teluk Jakarta. Sikap tersebut berupa menolak izin baru terhadap reklamasi dan membatalkan izin terhadap reklamasi pulau yang belum terlaksana.
"Yang baru terlaksana kan hanya beberapa pulau, sebagian jadi sebagian setengah jadi. Ini tetap akan distop‎," kata Marco di Balaikota DKI, Jalan Medan Merdeka Selatan, Jakarta Pusat, Selasa, (23/5/2017).

Untuk pulau reklamasi yang sudah jadi,menurut Marco peruntukannya akan dialihkan untuk kepentingan publik. ‎Oleh karena itu diperlukan audit lingkungan untuk mengkaji seberapa besar dampak pulau reklamasi bagi lingkungan serta masyarakat pantai utara jakarta.
"Jadi audit lingkungan bukan untuk meneruskan reklamasi. Audit lingkungan untuk menentukan langkah-langkah apa yang tepat utntuk menindaklanjuti penghentian reklamasi dengan baik yang sesuai koridor hukum dan mengembalikan keadaan lingkungan dengan baik," paparnya.
Adanya audit lingkungan merupakan usul dari tim pemprov DKI yang melakukan pembahasan bersama tim sinkronisasi Anies Baswedan - Sandiaga Uno. Asisten Pembangunan dan Lingkungan Hidup Sekda DKI Jakarta, Gamal Sinurat mengatakan sebelum menghentikan reklamasi sebaik dilakukan audit terlebih dahulu.
"Supaya nanti program berikutnya lebih tahu, jadi tahu apa yang mau dilakukan di atas pulau-pulau terbangun itu. Itu hal yang cukup berbeda dan signifikan," katanya.
Audit lingkungann sendiri, nanti menurut Gamal akan dilakukan oleh dinas lingkungan hidup pemprov DKI. Audit hanya dilakukan terhadap pulau reklamasi yang kadung jadi.
"Yang akan (reklamasi) kan nanti berhenti," pungkasnya.

Sumber : Tribunnews.com

Ilmuan Menemukan Bagaimana Larva Karang Bereaksi Terhadap Stress di Taiwan

UC Santa Barbara mempublikasikan hasil penelitian bagaimana larva karang bereaksi terhadap tekanan lingkungan, untuk memahami dampak perubahan iklim terhadap terumbu karang.

Hasilnya? Larva tidak dapat mentoleransi stress.  Hasil peneltian dipublikasi dalam Proceedings of the Royal Society B. 

 

 

"Penelitian ini benar - benar mencerminkan bagaimana laut berubah lebih hangat dan asidifikasi berdampak pada kemampuan penyebaran larva karang dan kontribusinya membentuk koloni baru" kata Gretchen Hofmann, professor pada UCSB's Department of Ecology, Evolution and Marine Biology. "Jika indukan mampu menghasilkan keturunan yang kuat, makan akan ada harapan untuk melihat karang mampu beradaptasi dengan perubahan iklim"

Bimbingan Hofmann, Emily Rivest dan rekan di Taiwan mempelajari larva Pocillopora damicornis dari Moorea dan Taiwan, lokasi yang mendekati wilayah penyebaran spesies. Mereka bertujuan mengetahui bagaimana karang muda bereaksi terhadap 2 kondisi stress yang muncul bersamaan : peningkatan suhu dan pengasaman (asidifikasi) laut.

Spesimen dari taiwan ditemukan kurang toleran terhadap kenaikan suhu air, dibanding spesimen dari Moorea.  Terhadap asidifikasi, kedua spesimen tidak menunjukkan tanda stress.  Peneliti mengumpulkan larva dari spesimen dewasa dan melepaskannya di lokasi percobaan pada malam hari.  Kemudian peneliti mengambil lemak (lipid) yang diuji strukturnya.

"Meskipun tidak ada satu solusi yang sesuai untuk semua, terlihat bahwa ada tempat di mana karang akan tumbuh dengan baik di bawah kondisi perubahan di masa depan. Jika kita terus berupaya dalam hal ini, maka kita dapat membantu mengidentifikasi terumbu karang yang akan lebih tahan terhadap perubahan iklim akibat manusia. " Kata peneliti.

Sumber : www.sciencedaily.com