Monday, August 4, 2014

BRUV analysis



As part of the UNDP/GEF Protected Area project, Baited remote underwater video (BRUV’s) were taken from 22 sites around Denis Island with the help of MCSS in April 2014.  Sites were chosen at two of the main dive sites and then around from the North point of the island around the East coast and around the South point.  It was originally planned to have at least 4 surveys in each area but because of sea conditions and other unforeseen circumstances, in the end only 20 sites were done.  

The videos were viewed and the monitoring started between 3 and 12 minutes after deployment in order avoid disturbance from boats and people.  The area surveyed covered the area between camera and bait canister and approximately 1m behind the bait canister.  All predatory fish in this area were recorded and the highest number of each species in one shot at any one time during each video was recorded.  All other sightings of megafauna were also recorded throughout the video whether they were in the survey area or not.  This included sharks, rays, turtles, Bumphead Parrotfish and other rare/unusual sightings.  The time and video of these sightings were recorded in a separate sheet.  Each shark will also be analysed to try and determine number of individuals and estimate abundance of each species. Abundance from each site was accumulated into the designated areas and the total abundance was calculated.
 
As expected the largest abundance and diversity was found at the dive sites with more being found at Batfish compared to Aquarium.  This was also true of Megafauna sightings with all sharks in this area being seen at Batfish.  Turtles and Bumphead Parrotfish were seen at both sites.  Here the size of the predators was also much larger than around the Island as expected.


The shark sightings were initially only recorded for the first 60 minutes of monitoring, but most videos were longer than that and it was found that many sharks were only attracted to the BRUV after this time and so monitoring was extended to allow monitoring of all sharks in the entire video time.  4 different species of shark were observed using the BRUV surveys; Whitetip Reef Shark (Triaenodon obesus), Grey Reef Shark (Carcharhinus amblyrhynchos), Tawny Nurse Shark, (Nebrius ferrugineus) and Sicklefin Lemon Shark (Negaprion acutidens). An additional sighting of a Black Tipped Reef Shark was also captured on video in front of the dive centre at the time of the surveys.  Sharks were analysed using sharks per hour as all the videos were different lengths.  Using sharks per hour as opposed to abundance counteracts this discrepancy.


These surveys show that Denis Island boasts a healthy population of predators, especially sharks.  The dive sites are used by the larger predators such as the adult Groupers, Twinspot Red Snapper, and larger sharks shown by the presence of Grey Reef Sharks only at the dive sites and not on the reef flats.  The shallows are used by the smaller juvenile fish such as small emperors, snapper and grouper.  Looking specifically at the Paddletail Snapper (Seen in the image below with the Black tail), which was seen both at the dive sites and the shallow sites, the size difference shows that the reef flats are used as a nursery for these species.  The shallow areas also seem to be a nursery for some shark species such as Nurse Sharks which were much smaller in the shallows compared to on the dive sites.
This data also shows Denis Island as a very important area for sharks as not only were 5 different species seen, but also very different sizes from very small juveniles, to adults show that Denis is a host to different species of sharks all through their life cycle. 
Turtles were also seen using the BRUV’s both on the dive sites and in the shallows, showing that turtles also use this area frequently.  Combining this with the shallow water surveys that were done at the same time, and the turtle nesting data, it can be seen that many turtles, both Green and Hawksbill, use this area for everything from grazing and feeding to nesting. 


These results are promising, but are far from complete. Monitoring over different seasons is essential in determining the role of Denis Islands’ reef flats as a nursery and possibly a pupping area for the different species seen in this exercise. GIF and Denis Island hope to continue gathering this important data together with MCSS to determine how best to protect these areas.

Beach Profiling - Denis Island


During a beach profile monitoring exercise on Sunday February 2, 2014 -- where Gilberte Gendron, a research staff from the Seychelles National Parks Authority (SNPA) conducted staff training for those working for both Denis Island and the Green Islands Foundation (GIF), an NGO which focuses on environmental research on Denis Island - several Wedge Tail Shearwaters including chicks in a burrow of intertwined Casuarina roots on the coast were found.

The Shearwaters were unexpectedly discovered after the search for finding nesting green turtles by the staff produced no result.
Gilberte was invited by the GIF and it was her first trip to Denis Island and she was greeted on the island by Arjan De Groene, the general manager of GIF and Andre Labiche, the Denis Island environment officer.

Andre, very keen to attend this training, had already prepared all the necessary equipment including profiling poles, measuring tape, abney level and monitoring forms. A quick glance at the map and the existing survey points for profiling were located before the training started. The team had some difficulty locating the reference marks, but this did not hinder the training program which consisted of setting up temporary reference marks, with Gilberte giving detailed explanations of each step taken.

Andre starts his training.
Juvenile Wedge Tail Shearwater


  



Arjan recorded the data while Andre used the abney level to record the slope. A lot of emphasis was laid on the reading. Once this was completed, the team moved to the next point, and the roles were reversed, with Arjan using the abney level while Andre recorded the data.

Once everyone was happy that they could confidently conduct the beach profile monitoring, the training continued in the office. It was time to get familiar with the data entry program and a data entry session was undertaken where data collected in previous years were looked at.  Andre was then assigned the task of locating all the other reference marks, so as to complete the monitoring for the following months.

Since the training went quicker and more smoothly than was originally planned, Gilberte took the opportunity to brief the staff on the turtle monitoring protocol. It was decided that a turtle patrol should be conducted that same evening, with hopes of encountering a nesting green turtle. At 9pm the three left the office, along with Mala, a hotel staff and Eric, a dive instructor from the dive center, who had volunteered to join them.

After about a two-hour walk around the whole of Denis Island, they were back at the starting point, unfortunately without having encountered a single turtle. However, there was some excitement as another great discovery was made that night on the coast. Under a big Casuarina tree, a burrow had been sighted. Having a closer look through the intertwined Casuarina roots, several Wedge Tail Shearwaters, including chicks, were seen! The following day another burrow was spotted a little further down the coast, again with chicks.

It has been years since a Wedge Tail Shearwater chick had been sighted on the island and hope had been all but lost that the old breeding colony still existed. This discovery proves that Denis Island is again home to a small breeding colony of these magnificent seabirds. GIF and Denis Island will do their utmost to keep protecting the burrows and minimize disturbances in the hope of future expansion of the Shearwater breeding population.
Andre and Arjan continuing with the beach profiling

Friday, August 1, 2014

Vegetation Mapping Poster Denis Island


Protected Area Project




Strengthening Seychelles’ Protected Area System through NGO Management Modalities (PA Project)
GIF forms part of a large Protected Area Project, a UNDP supported project funded by the Global Environment Facility (GEF). This project includes many other organisations in Seychelles such as The Ministry of Environment and Energy, SIF, SFA, SNPA, MLUH, Nature Seychelles, MCSS and others.
The Protected Area project started in 2011 to create synergies between current Government conservation efforts and those of non-government partners in the establishment of new protected areas, and also to improve the management of existing terrestrial and marine protected areas.  The main outcomes of this project are:

For Marine Protected Areas:
•    designing a more representative system of marine protected areas that builds resilience against environmental variations associated with global climate change
•    facilitating the establishment of new or expanded marine protected areas and conservation zones that will more effectively safeguard habitats associated with fish spawning aggregations (e.g. rabbit fish, whale sharks, groupers) and coral reef ecosystems
•    strengthening the operational capacity of NGOs, artisanal fishermen and the private sector to establish and manage marine protected areas and marine conservation zones in a collaborative partnership with the SNPA and SFA
•    improving the policy, legislative and institutional framework for collaborative management between state and non-state partners in MPA management
 For Terrestrial Protected Areas:
•    designing a representative, adequate and comprehensive system of terrestrial protected areas
•    facilitating the establishment of new protected areas on privately-owned and state-owned islands under different co-management arrangements and using a range of different sustainable financing strategies
•    testing the feasibility of establishing and enforcing seasonal conservation areas for nesting turtle habitats
•    strengthening the operational capacity of NGOs, parastatals and the private sector to establish and manage terrestrial protected areas and
•    improving the policy, legislative and institutional framework for collaborative management between state and non-state partners in terrestrial protected area management.

What is GIF’s part in this?
GIF’s part of this project is to investigate if Denis and North Island qualify for protected area status while at the same time expanding the area of native habitats on each island. To do this, GIF are doing a number of specific projects aimed at getting this information such as;
·         Marine surveys and mapping on Denis and North Islands
·         Habitat mapping and rehabilitation on Denis and North Islands
·         Coastal restoration and reinforcement on Denis Island
·         Improving invasive alien species prevention measures on Denis and North Islands
·         Environment management plan development on Denis and North Islands
·         Mynah Bird eradication on Denis and North Islands
·         Wetland surveys and restoration on North Island
·         Endemic bird monitoring on Denis and North Islands
·         Sooty Tern breeding colony reestablishment on Denis Island

These individual activities will hopefully result in a proclamation package for proposal of Denis and North Island and/or important surrounding marine areas as part of the national protected area network.

More information on these projects will be given in more detail in future Blogs.