Monday
Nov032014

Beach Conservaton, Habitat Mapping

Habitat mapping continued this week to specify and locate the different species of mangrove trees within different forests along the coast. Based on maps created in June, there appeared to be a loss of sparse mangroves east of camp. However, without efficient mapping techniques it is difficult to clarify this loss. Therefore, GIS software will be used to map the coastal ecosystems within the area, such as mangroves, accurately. Thus, changes can be measured and confirmed. The causes of future changes in the ecosystems, natural or anthropogenic, will then be hypothesized to aid the conservation of such important habitats.

 
Q GIS software has been downloaded to map the species of mangrove and this will be done on top of a Google earth image of the coastline. Hence, the exact locations of the ecosystems in the south west of Nosy Be can be displayed accurately. Ideally, each species of mangrove will have an individual layer over the satellite image. This feature will allow the locations of single species to be observed throughout the coast irrelevant of the locations of the ecosystems as a whole. Thus, the most widespread and rare species can be highlighted and the reasons for their abundance predicted. For example, some species may be more sensitive to change and less competitive so are only found in a few of the sparse mangrove forests. When all the mangrove species layers of the GIS map are turned on (i.e. all species will be displayed over the Google Earth image), the most diverse forests can be identified and zonation patterns made clear.

Hopefully, this method will also be used to map the seagrass meadows and species within them. Zonation along seagrass beds is less dramatic than those in mangrove forests. However, it was clearly visible on during the excursion day to Ambataloaka last week. Three 50 m transects at increasing depth were carried out on the vast seagrass meadow by the Beach Conservation Team. The 12 random quadrats were placed along each transect following the methods described by the Net Seagrass Monitoring Program. Within each quadrat, the species were identified and their percentage coverage measured. Halophila sp. were found closest to shore, with Thalassodendron sp. existing in the deeper waters. Therefore, by creating individual layers for each seagrass species on the GIS map, zonation can be observed when all the layers are initiated, and individual species diversity around the SW of Nosy BE can be examined using the single species layers.

 
As the seagrass meadow at Ambataloaka is exposed to a large amount of boat moorings and therefore, fuel pollution into the water and anchor damage, it is predicted there will be significant differences in epiphyte coverage and species cover compared to sites that are exposed to fewer anthropogenic impacts. The density of the seagrass meadows will be able to be displayed by different shades/transparency of the individual colour used for each species on the GIS map. Hence, GIS will enable visible comparisons to be made between the seagrass ecosystems in the south of Nosy Be. These will be easily understood so future changes in all coastal ecosystems exhibited by the software are detectable.

By Conservation Apprentice, Kate

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Wednesday
Oct292014

The fascinating whale sharks

Madagascar is fortunate enough that for several months of the year, whale sharks migrate through their waters. Whale sharks can be as big as 20m making them the largest fish in the ocean. Despite their size they have extremely poor vision, only being able to detect movement 4m away. However, they compensate for this with their acute hearing and their ability to detect magnetic field changes as they navigate through the oceans. Their movements are slow and the maximum speed a whale shark can travel is 0.7 ms-1. They regularly dive up to 90m.

Whale sharks eat krill, shrimps and other small fish using two methods depending on the availability and abundance of their prey. More commonly they ram filter feed, this involves swimming into their prey with their mouths open. Or, the whale sharks active feed. This involves staying in one place and searching for food. Like humans, whale sharks are k-selected species. Therefore they breed small amounts of young who are born alive and take a long time to reach sexual maturity. Sightings of mature whale sharks are very rare due to their swimming patterns. 

Whale sharks are only protected in 10% of countries and thus they are increasingly vulnerable to extinction. With their numbers in decline their conservation has become more important than ever. Their main threat is human activity such as hunting the sharks. As they swim so close to the surface and so slowly, not only are they easy targets for boats but they also can ingest floating plastic, clogging their throats. Hunting the sharks can be for illegal trade in oil and fins. 647 whale sharks were caught between 1988-1991 and their meat discarded. In the early 1980s in Taiwan, 30-100 individuals were caught annually. Within the same decade the number fished reduced dramatically to only about 10 a year due to the dwindling population. Another threat to the sharks is heavy wave action or changing and heavy currents as this can lead to stranding. For example between 1984 and 1995 36 were found stranded on the South African coastline.

Contrary to damaging misconceptions whale sharks are not monsters and do not eat people. They are a delicate and gentle species and with this new education whale shark tourism is currently booming. Groups such as ECOCEAN have a code of conduct which they endeavor to get all whale shark centers to sign, setting strict guidelines of how to handle the whale sharks without threatening them. It includes limitations on the number of people allowed in the water with the sharks, a maximum of 10 at any time, the distance at which the tourists must remain, based in the whale sharks ability to detect movement, the distance and speed of the boats around the sharks and how to approach the sharks causing minimum disruption. However these regulations are rarely put into practice by the companies agreeing to them. 

Whale sharks are badly affected by this as they develop an increased tolerance to human contact which dulls their senses and their natural instincts. The damage caused to an animal in this way will stay with it for the rest of its life. In the worst cases of whale shark toutism they are fed which is known as 'chumming'. It alters their natural behavior and in some areas has led to whale sharks staying in the same area all year round. As a result their gene pool is narrowed, they receive a less varied diet and gain a strong dependency on the humans that feed them. Overall this decreases the population size and health, further increasing the threat to whale sharks.

Ecotourism is concentrated in poorer countries, such as here in Madagascar. We all experienced the lack of enforced guidelines first hand when we went on a whale shark excursion in Nosy-Be. More than 10 people were in the water with the sharks and an insufficient briefing lead to tourists and us remaining ignorant about the threats to whale sharks and how to treat them. The experience was incredible but we hope that regulations are tightened in coming years and with increased education about the species and the threats to them these breathtaking animals can be ensured a future in our seas. 

By Lulu, Research Assistant 

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Wednesday
Oct292014

Volunteer blog: Marine Pollution

The rising levels of litter and other pollutants collecting itself on beaches and oceans worldwide have posed massive threats to the marine world, as plastic has affected 44% of sea birds, 86% of all turtle species and 43% of all marine mammal species. Other hazards, such as oil spills and dumping, are other major causes of concern to the marine environment, which must be prevented. Such methods include recycling, enforcing laws and changing habits on an individual level. 

Part of the problem begins with litter on beaches. In 2003, 244 beaches were surveyed, producing results of 2074.5 items of litter per kilometer. One of the major reasons for this is beach visitors. Many people simply leave their trash on the beach not thinking about the repercussions. One of the biggest pollutants is plastic. Of the turtles surveyed, 75.9% of them had ingested plastic. Additionally, sea birds mistake it for small pieces of food, which they ingest and feed to their young. In surface waters, for every 0.5kg of plankton, there are 5kg of plastic. The effects of this can cause death and reproductive problems due to toxicity of the plastic, which could eventually bioaccumulate, reaching the human food chain. 

However, there are a number of other issues we have to take into consideration. Dumping, whether legal or illegal, has created lots of problems to marine life.  Dumping of solid wastes, sewage sludge and other bulky items, such as concrete, steel and iron, can damage coral reefs, be ingested by animals and disrupt the food chain. Oil spills have also affected the marine world by smothering birds, killing them and reducing hatching success, as well as killing other animals by them over-consuming it. An estimated 1.7 to 8.8 million tonnes of oil are released into the marine environment each year.

This can all be reduced and potentially prevented through recycling or even biologically grown plastics, which are biodegradable. Additionally, better legislation could be implemented enforcing bans on dumping. Finally, improvements on an individual level could be made, which could largely reduce the level of litter collecting itself on beaches.

Worldwide many animals are dying due to marine pollution, however, this could all be prevented or reduced by a number of methods including improvements on an individual level, as well as research and development. From time to time, a simple beach clean can make a difference and we can all make small contributions in achieving our goal.

By Nick, Research Assistant Volunteer

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Wednesday
Oct292014

Volunteer blog: Herp-spotting

The trainspotting like appeal of keeping a species list is hard to explain but for any long term forester, it becomes an essential item. It begins as a necessary way to keep track of the numerous species encountered in the forest but soon the gaps begin to show and a need for completeness takes over.

Day geckos of the Phelsuma species are not hard to find, the 6 local species being bright green or bluish in colour. It didn't take long to find the first four of this set. Even the rarely seen Phelsuma quadriocellata was spotted high in a travellers palm. This left only P. dubia or the "dubious dubia". So called because it's most easily identified on the basis that it doesn't quite match the description of any of the other species. A few weeks passed with no luck, until two geckos were spotted in a palm a couple of metres from camp. These lizards most closely resembled P. grandis, too large to be another Phelsuma and sporting red dorsal spots. However these lizards were duller with a bluish tint and pale underside. Additionally they lacked the red facial markings of the grandis. A dubia! Likely living in camp all along.

 Next there were the snakes. More illusive than most lizards, any day with a snake sighting is a good day. I was lucky, seeing 10 out of the 12 local species in just a few weeks. This left only the Bibilava stumpffi and Madagascarophis colubrinus, the cat-eye snake. My chances seemed low with only a single Bibilava stumpffi and zero cat-eyes being sighted since my arrival. But 6 weeks into my stay the nocturnal cat-eye was sighted! Another sighting the week after, but always on the other night walk to me. My last week comes around and I decide to a night off and let some other foresters go on the night walk. I go for some sausage, chips and pizza served in the village. Alas, another cat-eye was found on that nights walk. Typical! 

The next evening there would be a snake hunt in primary forest, the ideal opportunity. But of course, nature is full of surprises. There were no cat-eye snakes found on this hunt but two other species, I had yet to see, made an appearance. A tree frog and a chameleon! The frog, seen sitting on a leaf, lacked the prominent hip of other tree frogs giving it an overall fairly rounded shape. This could be one of two indistinguishable Cophyla species, differentiable with confidence only by genetic analysis. I'll never know for sure. Still a tick, albeit an unclear one. The chameleon, Brookesia ebenaui, is rarely seen as it generally lives higher in the canopy. But this night two were found in plain sight. Initially very similar to the common Brookesia stumpffi, this small blocky chameleon has additional horn like appendages and spikes running the length of the body and tail. No cat-eye today but this walk had already been a success.

Earlier that same day I had the luck of seeing a Caluma nasutum. Another chameleon species rarely seen in this area and a first for me. This small, brownish lizard was spotted climbing though leaf litter in a dried up riverbed. The Caluma species on Nosy Be are a much slimmer genus and lack spikes. Additionally, the Calumas sport a sizable rostral appendage resembling a comically large nose. Combined with its wide mouth and slight frown these chameleons appear to be in a constant state of disapproval, making them a personal favourite.

There's always an extra element of excitement when finding a new species to tick off the list, it always makes memorable walk. But these things can't be forced. It is the unexpected surprises which make forest walks so enjoyable and unmissable. I've been lucky enough to see a large proportion of the species present on Nosy Be but there's always more. And who knows what the oncoming rainy season will bring?

By Will, Research Assistant Volunteer

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Friday
Oct242014

Staff blog: Black Lemurs

Madagascar contains some of the most varied habitats in the world. Lemurs, the prosimian of Madagascar, adapted into many forms due to this and filled many niches. Impressive as the unique lemur diversity of Madagascar is, the survival of this diversity has been threatened since the arrival of humans on the island which has caused fragmentation and loss of their natural habitat. More than 80% of forest cover has been lost already and at least 17 species of lemur have become extinct. All lemur species are currently threatened by habitat fragmentation, while they comprise more than 16% of all primate species existing globally. 

Nosy Be is home to the black lemur (E. macaco macaco), a frugivirous medium sized lemur. This species shows the most extreme sexual dimorphism found in Madagascars primates. Males have a black pelage with black ear tufts. Females have a golden-brown to chestnut brown dorsal pelage, while their ventral pelage is often off-white. Their head is pale gray and the ears are tufted with long white hairs. Both sexes have yellow-orange eyes. Mating season takes place in April and May and females give birth to a single infant between September and November. We are currently able to see the infants on our walks in the forest. Today we saw a female and male infant already leaving the safety of their mother to play with each other. Even though the sexual dimorphism of infants is not as marked as that of adult animals, the white ear tufts of the females are still visible.   

The geographic range of black lemurs is restricted to the moist Sambirano forests and the similar humid forests on offshore islands in the north of the island. Although black lemurs are threatened by loss of habitat throughout their small geographic range they have shown adaptability to human altered environments and are known to inhabit primary, secondary and degraded forest. On Nosy Be they are present in the strict forest nature reserve of Lokobe, but are also found in secondary forest, old-crop plantations and agricultural patches in the forests surrounding villages. On Nosy Komba, an island close to Nosy Be, black lemurs live at the highly degraded edge of forest. Here locals feed them for ‘tourist experiences’ and as a result the lemurs are totally habituated. Although this provides a source of income for the locals, current methods are unfortunately highly damaging for the animals. Research on the effect of human disturbance on lemur behaviour is very important for future conservation planning, especially with the current threat of further habitat loss and increasing interaction with humans in their living environments.

By Nicky S.  Terestrial Assistant Research Officer

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