The use of electronic animal tracking has revolutionised marine science and conservation; in recent years, animal tracking has become incredibly sophisticated and allowed scientists to observe behaviours that had so far remained completely unknown. Tracking devices are getting smaller allowing them to be attached to a wider range of species, whilst at the same time, battery technology is improving which allows the recording of longer time series of data. Sensors are also becoming more sophisticated so that scientists are now able to observe not just the location of tagged animals, but also their speed, acceleration and even, in the case of sea turtles and seabirds, whether they are in or out of the water. From this wide range of data, scientists are able to recreate the most detailed pictures of animal behaviour.
Prof. Graeme Hays of Deakin University with Dr. Nicole Esteban from Swansea University and Dr. Jeanne Mortimer has been studying turtles in the British Indian Ocean Territory for many years. Their work, which is an integral component of the Bertarelli Foundation’s marine science programme, has been utilising satellite tracking technology on Green turtles which has shown them travelling as far as the coast of Somalia – over 4,000 km away to the west. Dr. Esteban recently returned to BIOT to attach satellite tags to Hawksbill turtles for the first time; once the data from these tagged animals are analysed it will help give the team an even better understanding of how the Territory’s MPA protects sea turtles in the Indian Ocean.
The Chagos Archipelago is an important refuge for seabirds in the middle of the Indian Ocean – one of the planet’s most heavily exploited oceans. Researchers from the Zoological Society of London and Exeter University have been studying populations of Red Footed and Brown Boobies on the islands of Diego Garcia and Nelson Island to learn more about how they use the Territory’s Marine Protected Area. They recently traveled further north to the menacingly named Danger Island to find out how the populations there differ in their behaviour and foraging habits. Hannah Wood took some time out to send us this update from the field:
Hello from Danger Island in the Indian Ocean! I am writing this blog from our campsite by the beach, sitting amongst a grove of squat, leafy beach heliotrope full of small, white moths and unexpectedly arboreal hermit crabs. Today is thankfully overcast which gives us a break from the intense sunshine and lessens the sweltering heat. The sea is relatively calm at the moment, but the coral reef fringing the island means that there are always white-tipped breakers rolling and crashing into the shore.
We arrived here six days ago with the aid of British military forces and a British patrol ship. With their help we unloaded camping gear, drinking water, food for two weeks and all our science equipment. It took us the rest of the day to set up our camp and the following morning we circumnavigated the island to assess potential tagging locations. That afternoon we began tagging red-footed boobies with tracking devices, and by the end of the second day we had tagged 33 nesting birds.
Once the red-footed booby tagging was complete we moved on to the brown boobies, which are slightly larger and nest on the ground under bushes rather than in the trees. We have now tagged 15 of these and hope to begin retrieving the tracking devices tomorrow! In addition to all the tagging we have been conducting twice daily monitoring of nest attendance at all of our 33 red footed booby study nests, and erected a long-term camera trap near a collection of booby nests.
The tag recovery phase of this expedition has now begun; this morning we collected six of our devices from red footed boobies, hopefully full of interesting data! As the afternoon passes it should get cooler and we can head out to gather more tags, until then we are recharging our electronics with portable solar panels and recharging ourselves with powdered isotonic drink!
As part of the Bertarelli Foundation’s marine science programme, we have funded a long-term study of sea turtles in the British Indian Ocean Territory with the aim of learning more about the biology of the incredible animals and to determine how effective the MPA is at protecting them.
In the midst of the researcher’s expedition to Diego Garcia, British Indian Ocean Territory (BIOT), Dr Nicole Esteban provides an update on her work:
The second sea turtle expedition to Diego Garcia in 2018 is underway. Earlier this year we focused on nesting green turtles and this time we are in BIOT during peak hawksbill nesting season to find out more about this critically endangered species. One of our key conservation research objectives is to increase our understanding of hawksbill turtle nesting in BIOT and their post-nesting movements within and outside of the Marine Protected Area.
Unusually for turtles, hawksbills nest during the daytime in the Western Indian Ocean and often emerge to lay their egg clutches during the incoming tide. So we targeted beach patrols for nesting turtles in line with the daytime incoming tide, either starting patrols early afternoon or before dawn. To maximise our chances of finding turtles, we patrolled a 2.8 km beach in the southeast of Diego Garcia as this stretch of beach has one of the highest turtle track densities on the island and is easily accessible. Hawksbill nesting can be completed fairly quickly and they can return to sea just 45 minutes after emerging so we divided into two groups that patrolled 1.5 km of beach every 40 minutes to ensure we saw any hawksbill that emerged to nest. We were lucky to have assistance from over 50 volunteers to patrol the beach, move the restraining boxes and help with satellite tag attachment.
We were amazed to encounter five nesting turtles on our first day of patrols (four hawksbills and one green turtle). All the hawksbill turtles were measured, flipper tagged and a biopsy taken for DNA analysis. During subsequent days, we saw six more hawksbills. The nesting hawksbill turtles were fairly small and ranged in size from 74-86 cm (curved carapace length).
We attached satellite tags to five of the nesting hawksbills. The satellite tag attachment takes around 2 hours: first the carapace is cleaned, sanded and then cleaned with acetone (nail varnish remover), then the satellite tag is embedded in epoxy paint and lastly painted with a coat of antifoul paint before being left to dry. The satellite tag process is the same as we have used for green turtles (see how we have attached satellite tags on green turtles; https://tinyurl.com/yccp7aur). We keep the turtle cool with shade and by pouring water on the carapace, head and shoulders.
By the end of the expedition, we will have completed two weeks of nesting activity surveys to find out more about nesting emergence timings and the size of the nesting population in Diego Garcia. This will help inform timings for our expedition in November 2019 when we will continue our work with nesting hawksbill turtles. Satellite location uplinks are showing that all the satellite tagged hawksbills are still just offshore of the nesting beach, so we expect they will continue nesting every 12-14 days. In this way we will learn more about how many nests they lay in a breeding season before returning to their foraging grounds.
We wait with baited breath to see the migration destinations of these hawksbill turtles. If you’re interested to receive updates, please join our ‘Chagos Turtles’ Facebook Group .
On Tuesday 11th September 2018 the inaugural marine science symposium for the Bertarelli Programme in Marine Science (BPMS) took place at the Royal Geographical Society in London. This one-day symposium brought together scientists, students, conservationists, policymakers and Marine Protected Area (MPA) managers to listen to presentations highlighting key research being undertaken in the British Indian Ocean Territory (BIOT). This impressive line-up of speakers included keynote presentations from Amb. Peter Thompson, the UN secretary General’s Special Envoy for the Ocean, the New York Times’ journalist, Ian Urbina, recounting stories on ‘outlaw ocean’, and a special video message from HRH the Prince of Wales.
The Bertarelli Programme in Marine Science includes more than 60 scientists and marine conservationists from across the world all studying the BIOT MPA to help determine how effective this large, remote MPA is at providing species protection and resilience. The symposium showcased the work of the first year of programme activities as part of the first phase of the programme which runs from 2017 to 2021. Following an introduction by Heather Koldewey, ZSL’s Head of Marine and Freshwater Conservation and Programme Lead for BPMS, and the keynote presentations, the scene was set ready for the programme presentations which introduced us to work from across the programme during three key sessions:
The Open Ocean
Reefs to Islands
Applying Science to Management
The open ocean session introduced the work being done using different technology to track and investigate how sharks and other pelagic species use the MPA, the networks identified and how oceanography can help us to understand how wave dynamics create predator hotspots within BIOT. The reefs and islands session covered the status of coral reefs and investigations to better understand their role in the archipelago and across the Indian Ocean and the use of bio-logging technology to investigate how species such as turtles and birds use the MPA. Nick Graham, Lancaster University and Principal Investigator of the reef fish project, explained their recent work identifying the link between rat infested islands, the presence of birds and the impact this has on the health and biodiversity on the nearby reefs.
The final session linked the science to management, highlighting the important role science plays in informing management and the use of large MPAs as a conservation tool. After the close of the symposium, guests joined a reception to celebrate marine science and to digest all the information communicated throughout the day. With 2018 as the International Year of the Reef, thoughts are driven to how we can best protect our oceans, what is being done to protect them and how we can raise the profile to ensure we work collaboratively across the world to tackle these pressing questions.
All presentations from the events are now available to watch on our YouTube channel here.
It has long been known that the introduction of invasive species can have a detrimental effect on native flora and fauna. Rats decimate seabird populations all around the world by eating eggs and chicks – and sometimes even adult birds.
The British Indian Ocean Territory includes the Chagos Archipelago and 58 tiny islands. Some of the islands are home to the Black rat (Rattus rattus), whereas others have mercifully remained rat free. Researchers from the Bertarelli Programme in Marine Science have used these two types of islands – with rats and without – to see what effect the prescence of rats has on the health of the surrounding coral reefs.
Prof. Nick Graham commented:
“The islands with no rats are full of birds, they’re noisy, the sky is full and they smell – because the guano the birds are depositing back on the island is very pungent. If you step onto an island with rats, there are next to no seabirds.”
On rat-free islands, seabirds including boobies, frigatebirds, noddies, shearwaters and terns travel hundreds of kilometres to feed out in the ocean. When they return to the island, they deposit rich nutrients from the fish they feed on.
Prof. Nick Graham of Lancaster University considered whether these nutrients were being leached into surrounding waters and were influential in the biology of the reef systems. The findings, published today in Nature, are stark – fish on reefs adjacent to rat-free islands grew faster and larger compared to those fish living adjacent to rat-infested islands.
As coral reefs are regularly affected by changes in ocean temperature and the frequencey of coral bleaching events increases, this research suggests that the removal of invasive species like rats, could become an important way of increasing the resilience of these essential habitats.
Dr Ines Lange, marine biologist and postdoctoral research fellow at the University of Exeter, a project partner in the Bertarelli Programme in Marine Science, took part in an expedition to study the coral reefs of the British Indian Ocean Territory. Here’s her report from the very wet and windy Indian Ocean:
Prof. Chris Perry and myself from the University of Exeter are studying the carbonate budgets of coral reefs around the islands of the Chagos Archipelago. The “Reef Budget” method we use was developed by Chris and calculates how much carbonate is produced by corals and calcifying algae, and how much is eroded by grazing sea urchins and fish, as well as by internal bioeroders such as boring worms and microorganisms. The results provide a metric of reef “health” in terms of whether it is growing or eroding.
The sites in Salomon and Peros Banhos we visited so far show a dramatically reduced coral cover due to the severe bleaching event in 2016, causing carbonate production rates to drop to about a third of the values in 2015. On the upside, there are many Porites and also some Acropora colonies that apparently survived the bleaching, and large numbers of small recruits of different genera. Especially in the understory of the reef structure, we find many live encrusting corals. Also, the substrate is quite clean of macroalgae, thanks to the high abundance of grazing herbivorous fish. Calcareous algae covering the dead coral substrate continue to produce substantial amounts of carbonate which help “glue” the existing structure together and offer a great substrate for further coral recruitment. We therefore hope we can see a fast recovery of the once glorious reefs over the next years.
To investigate local bioerosion rates in the reefs we had a “fun” day sawing 1,000s of blocks from dead Porites skeleton (well, it certainly felt like that, on my last count it was actually 28).
We will deploy the substrates at Peros Banhos, where they will be settled by encrusting and bioeroding organisms. As you can imagine the work days are long, but the company is great and the sunsets quite impressive. Yesterday, a bird tried to land on our heads. Today, I watched eagle rays dancing. New adventures every day…
The Bertarelli Programme in Marine Science maintains an array of acoustic receivers around four islands of the Chagos Archipelago in the British Indian Ocean Territory. This battery of listening devices picks up signals from tagged animals (mostly reef sharks) as they pass by and helps scientists build up a picture of how these important predators use the Marine Protected Area and interact with each other.
Towards the end of 2016, a huge storm hit the Chagos Archipelago which was strong enough to separate our Vemco VR4 Global buoy from its mooring and push it off into deep water; for the next 11 months, the buoy drifted with the currents towards the east coast of Africa. Scientists at Stanford University plotted the buoy’s course and waited, with the intention of mounting a rescue mission, until it got close enough to land. Finally in July of 2017, the buoy ran aground over 3,500 km away on a reef near the small fishing town of Kilwa Mosoko in Tanzania.
We managed to get in contact with a small local holiday lodge and asked if they could assist in the buoy’s recovery. It took more than six hours – and 17 people – to maneuver the heavy equipment into a hand-made canoe and bring it ashore. Then it was carefully looked after by staff at the Kimbilio Lodge until Taylor Chapple and Robbie Schallert of Stanford University were able to collect it.
We’re very grateful to the people of Kilwa Mosoko. Because of their help and assistance, the buoy will soon be back in the Chagos Archipelago tracking tagged fish so we can better understand the effectiveness of the Marine Protected Area.
In a final report for the Bertarelli Foundation funded expedition to the British Indian Ocean Territory, David Jacoby, a postdoctoral researcher at the Institute of Zoology, describes his experiences over the last few weeks:
Every good story about the sea has, at its heart, the relationship between its characters, their boat and Mother Nature. Our voyage into the protected waters of the British Indian Ocean Territory (BIOT) has been no different and our research vessels, the Tethys Supporter and its three tenders, have been both our best friends and our worst enemies.
Like a reef fish waiting for the dangers of the night to pass, I write from my bunk, hunkering down out of the way of the most recent weather to pass through, today bringing lower winds but more swell. I think we all agreed some time ago, that there was something about this particular expedition that was never going to be easy, and so we’ve started to embrace the uncertainty. The Chagos Archipelago can be temperamental at the best of times and we have been getting the full spectrum since we set sail. Despite that, the entire team headed up by expedition lead Taylor Chapple from Stanford University, have pushed the limits of workable hours to get as much done as possible and navigating some tricky diving conditions to service a considerable number of our acoustic receivers. While a couple of our more exposed receivers have been lost to the elements, the occasional break in the weather has brought some shining victories.
Yesterday, for example, we arrived at Swartz and Sandes seamounts and positioned ourselves over the submerged summit to fish for sharks. At once we found ourselves in a maelstrom of large sharks, the usual suspects but many more silvertips than we’d seen before and even the illusive silky sharks made an appearance. Needless to say, we made hay and deployed numerous tags. There’s something incredibly satisfying about hand-lining for sharks, knowing that once they leave your boat again, they are carrying the instrumentation that will give you some insight into their lives and movement patterns. In short, they have now become part of the cohort for this ambitious study. That’s the scientist in me getting excited. The kid inside of me just loves being able to get so close-up and personal to these beautiful and perfectly adapted marine predators.
And so we move to the business end of the expedition. Everything is now covered in a healthy crust of salt, the majority of the receiver servicing is now complete and over 60 tags have been deployed including acoustic and pop-off archival satellite tags. By chance we’ve had everything but the kitchen sink thrown at us during this expedition and so I feel confident in saying that all things considered this has been a herculean effort so far and we’re still not quite done.
For more science updates from the British Indian Ocean Territory, follow @BIOTscience on Twitter.
In his last update from the British Indian Ocean Territory, David Curnick described some of the things they hoped to accomplish during the current Bertarelli Foundation funded expedition. Now, as his time in the Chagos Archipelago is drawing to a close, he described a worrying observation, but also a glimmer of hope for the future:
We are over half way through our expedition to the Chagos Archipelago in the British Indian Ocean Territory and have visited most of the major islands and atolls in the northern half of the reserve over the last week or so. Thankfully the worst of the weather has now passed and we are well into the groove of servicing the 76 acoustic receivers we have out here. Yet, with every dive, it has become apparent that all is not quite as I remember previously.
It may be the passage of time casting a rosy hue over my eyes, but on my previous visit to these reefs in 2014, I recall seeing a lot more sharks, and bigger ones too. Back then, upon jumping into the water and once the bubbles had cleared from the front of your mask, you were met by a least a few inquisitive silvertip sharks whose curiosity would drive them to check out any foreign body entering their reef home. I have yet to experience that this year. The welcoming party is simply nowhere to be seen. Sure, we are still seeing sharks on nearly every dive and it is the exception, rather than the rule, that a dive passes without a visit from at least one grey reef or white tip reef shark. However, in previous years it wasn’t uncommon to be circled by a posse of dozens. So, what has happened to the reefs residents in the intervening four years?
Perhaps we have just been unlucky this time around. Perhaps the recent storm and resulting reduction in visibility has meant that the sharks have been there but that we couldn’t see them. While both might be contributing factors, I fear more sinister processes might be at play.
Over the last few years, the reefs of the Chagos Archipelago, like many reefs across the world, have been hit by mass coral bleaching events. The severity of the bleaching has left reefs on their knees, littered with dead coral and broken rubble. I therefore wouldn’t blame a reef shark if it decided to pack up its bags and seek pastures new.
Perhaps it’s those rose-tinted glasses again, but maybe the cooler water at depth, where the impacts of warming water are at least somewhat diminished, is acting as a refuge in times of trouble. Therefore, maybe the sharks are simply residing just beyond the beady eyes of SCUBA divers. Yet while coral cover is down, there are still a healthy number of reef fish going about their daily routines.
Therefore, for species like silvertip sharks, the table is still set, and the dinner is ready to be served but few are home to enjoy the feast. Notable are large numbers of smaller predatory fish like groupers, snappers and the speedy trevallies patrolling the reef edge. Perhaps benefiting from the reduction in the reefs top predators.
The main theory for the disappearance, and probably where the Occam’s razor principle points, is that these sharks are simply being lost to the threat of illegal fishing. Records of vessels caught poaching within the reserve’s boundaries show that these fishers, predominantly from Sri Lanka and India, are indeed targeting sharks. It therefore may be that the endearing curiosity of the sharks has ultimately led to their downfall. Brazen and inquisitive enough to approach divers, bold and curious enough to bite down on a tantalizing piece of bait. Indeed, we know from the reserve’s patrol vessel that a large-scale illegal fishing event in late 2014 resulted in mass shark casualties. Glancing at the data we received from our sharks tagged at the time, a whole cohort of tagged sharks “went silent” within days of each other, never to be heard again. While we can’t conclusively say we lost our tagged sharks to illegal fishers, it certainly seems highly likely.
So, as we sit here counting the relatively small numbers of sharks we have seen on this trip, we find ourselves determined to help return these reefs back to those halcyon, shark filled days. On this expedition we are tagging reef sharks to better understand how these animals are using the habitats of the archipelago, how and when they move between them, and then use this information to better inform that management of the reserve. Thus far we have tagged 33 sharks and are targeting over 100 before we leave next week. Assuming the weather holds…
As for the reefs themselves, the Chagos Archipelago has, in the past, expressed an incredible resilience to bleaching events and an ability to bounce back quickly. Indeed, while on every dive we see large crumbling plates of Acropora tables, we also see every one covered in tiny coral recruits, the future engineers of the reefs regeneration. It now just remains to be seen how big they can grow before the next coral bleaching event. Here’s hoping for a good few years respite.
For more science updates from the British Indian Ocean Territory, follow @BIOTscience on Twitter.
The Bertarelli Foundation’s latest expedition to the British Indian Ocean Territory is underway with scientists planning to download data from an array of shark tracking receivers located around the Chagos Archipelago. David Curnick, postdoctoral researcher at the Institute of Zoology, brings us an update on the first few days:
As I write this blog we are currently moored off of Nelson Island, a small isolated island in the middle of the Indian Ocean, being circled by hundreds of frigate birds, terns and boobie birds. It is one of over 60 such islands that make up the British Indian Ocean Territory. But why am I here? The British Indian Ocean Territory was declared a no-take marine reserve in 2010 and since 2012 we have been tagging sharks, mantas and tunas here to better understand how they are using the reserve’s waters and ascertain how effective the reserve is at protecting them.
This year I am part of an international team of scientists, funded by the Bertarelli Foundation, onboard the Tethy’s Supporter, a vessel that came across from the Seychelles to support this expedition. We rendezvoused and boarded the vessel in the Maldives six days ago but unfortunately the weather has not been on our side thus far. Our two-day transit down from the Maldives was dogged by choppy seas resulting in our boat bobbing around the ocean like a child’s bath toy. Those transit days were spent checking dive gear and prepping shark tagging equipment, whilst the nights were spent trying to get some sleep although the ocean and the boat were working in perfect tandem to try and roll us out of our bunk beds. I was regretting my foolish and naive nabbing of a top bunk. It’s a long way down to the cabin floor…. After two pretty much sleepless nights, we were all relieved to arrive to the relative calm of Salomon Atoll. Once inside, we were sheltered from the big swell that had been raging from the west and were able to get some much-needed rest.
The following morning, we divided into two teams to set about our primary objective, to service the extensive acoustic receiver array network we have installed around the atolls out here. Each receiver logs the occurrence of any tagged shark that may swim within its detection range (~500m) and we have installed 76 such receivers across the archipelago over the last few years. On this expedition we will be SCUBA diving on each one (~20-25m), replacing the old receiver with a fresh new one, and bringing the old receiver to the surface to download the data. That’s the exciting bit – finding out what it has recorded over the last few years.
Our first morning however didn’t quite go to plan, with the persistent swell meaning we weren’t able to access some of our sites around Salomon safely in our dive boats. It was no trouble for the resident spinner and bottlenose dolphins however, who we could see effortlessly playing in the rough water around the atoll almost mocking us with the ease with which they managed the swell. Still, they were very cool to see.
As the acoustic array can only detect animals that have been equipped with specific acoustic tags, we of course have to attach these devices to animals. However, the weather conditions have just made it too tricky to tag any sharks or manta rays just yet. So, for now we are focusing on servicing as many receivers as we can and will focus on tagging more once the weather improves. After servicing all of the receivers that we could around Salomon, the following morning we headed west to Peros Banhos atoll. This massive atoll (~25km across) is where the vast majority of our receivers are located. A few days servicing receivers there we headed east to Nelson Island where we are now anchored.
The good news is that the weather is clearing so a shark tagging boat should be going out this afternoon. Will update you on what we catch in the next blog…
For more science updates from the British Indian Ocean Territory, follow @BIOTscience on Twitter.
The Bertarelli Foundation has, for some time, supported a number of projects in the Indian Ocean which use tagging technology to further our knowledge of animals such as sharks, tuna, manta rays and sea turtles. By following their migrations, sometimes over great distances, scientists can begin to understand more about their behaviour and their ecology.
A scientific paper by Prof. Graeme Hays of Deakin University and Nicole Esteban of Swansea University recently published in Frontiers in Marine Science, suggests that tagging data might actually be used by scientists for another purpose – to map seagrass habitats. Not only are seagrass meadows a valuable habitat for many marine species but they also provide ecosystem services worth trillions of dollars (USD) each year. Seagrass meadows have a role in mitigating climate change, they protect coastal areas from erosion, and they improve the health of neighbouring coral colonies. Mapping seagrass meadows – and any changes in seagrass distribution – is therefore of vital importance to us all.
As part of the Bertarelli Programme in Marine Science the researchers have attached satellite tags to a number of species of sea turtle, including green turtles, in the British Indian Ocean Territory. This has provided valuable insights about how they range across thousands of kilometers, and even suggested how they might locate tiny islands in the vastness of the Indian Ocean.
Now the scientists have also shown that it is possible to use this tracking data to identify where seagrass meadows might be located and which areas warrant further investigation and survey.
In late April and early May, Dr David Jacoby of the Zoological Society of London and Dr Taylor Chapple of Stanford University spent a week at sea attempting to retrieve data from deep-sea receivers scattered across the marine reserve in the British Indian Ocean Territory. The receivers pick up signals from pelagic animals that the team tagged on previous trips including sharks, rays and tuna – the big predators that are hard to study but absolutely key to a healthy ecosystem. These 16 receivers were deployed in 2016 in a variety of deep-water habitats such as sea mounts and undersea canyons, places too deep for divers and until now virtually unstudied by scientists.
In just six days, with the help of the crew of the British Patrol Vessel Grampian Frontier, the team traversed the Chagos Archipelago from end to end travelling over 500 miles. They managed to retrieve 12 of the 16 receivers by using an automated acoustic release system which ‘calls’ the receiver from the surface causing it to break free of its mooring and float up to be collected by the team.
Early analysis of the data from the receivers has revealed an incredible wealth of information; over 500,000 individual detections were downloaded – each one an individual pass of a tagged animal past one of the receivers. Receivers located at the Schwartz and Sandes seamounts in the south of the archipelago made detections of 159 unique individuals and are starting to reveal some of the connectivity between these deep habitats.
Additionally, an Acoustic Doppler Current Profiler, retrieved from ‘Manta Alley’ at Egmont Island has collected information about the current profiles of this newly discovered manta highway and will provide vital environmental data for assessing why this area if so important for this iconic species.
Though short, this trip was very successful and will reveal more of the habitats and movements of these amazing species around this huge marine protected area. The acoustic receiver array, funded by the Bertarelli Foundation, is contributing to a long-term data set that is unparalleled in its size and geographic coverage and continues to grow by the day. All the data are now on their way back to the lab at Stanford University for in-depth analysis.