Improving MPA Management

Webinar: Imaging in Marine Science

Imaging in Marine Science

In the latest of the Bertarelli Foundation’s marine science seminar series, Prof. Heather Koldewey introduces four speakers who are all using imaging technology for marine science.

Advances in technology have allowed scientists to capture the underwater world in new and innovative ways, revealing insights in to life in the big blue and providing data to help us better protect the ocean and the life within. This seminar will explore how different imaging techniques are applied to study the ocean and help provide a picture of what the underwater world is hiding.

Speakers:

Joanna Harris – Manta Trust and University of Plymouth
Dr Dan Bayley – UCL
Dr Greg Asner – Arizona State University and Allen Coral Atlas
Dr Jyotika Virmani – Schmidt Ocean Institute

You can watch a recording of the seminar below:

Below you can find answers to questions we didn’t have time to address during the live seminar.

If overcrowding from tourists is having negative impacts on manta rays, how are you encouraging responsible citizen science photography?

Joanna: Encouraging responsible citizen science photography is extremely important. The Manta Trust has engaged in extensive research and provided key recommendations that aim to ensure that the manta ray tourism industry remains sustainable and non-detrimental to the animals’ natural behaviour (Murray et al., 2019). The outcome of this research includes a 10-step guide on how to sustainably interact with manta rays (https://swimwithmantas.org/).

What is the timescale for taking all of the photos to make these 4D maps?

Dan & Andy: We have been monitoring the reefs around the Chagos Archipelago annually using the 3D SfM mapping technique from 2015-2019. To make a ~20 x 20 m HD map takes about an hour for a diver pair to set up the site and collect pictures. The processing time depends on the computer power, number of images and the image sizes, but can take from hours to a day for a site this size. If interested in more detail on this method, we recently wrote a ‘how to’ guide: https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/2041-210X.13476

On what scale have you developed the 4D maps? Are they limited to localised in-situ images?

Dan & Andy: Our projects have tended to be local, and the technique is usually applied over 10s to 100s of square metres, however it is possible to scale projects to larger areas. We are developing the use of an autonomous surface drone to cover larger regions of reef, and aerial drones commonly use this type of photogrammetry to survey multiple km². It is worth noting that typically to scale up projects, the height from the ground or reef needs to increase, and so the overall resolution decreases.

With these types of coral reef mapping (4D map analysis), would this tend to specialize data gathering and analysis for researchers? How can this be made more accessible to local managers or researchers who may have limited resources and skills?

Dan & Andy: In many ways, this technique democratises small-scale spatial data gathering compared to other methods. It is possible to quantitatively map several hundred square metres of seabed using a single camera, in-situ scales, a mid-range computer, and the requisite software. Total cost buying from scratch would be <£5k (though better cameras and computers will increase resolution and decrease processing time). Mapping the same area with a multibeam sonar or lidar system would typically cost an order of magnitude more for the sensor alone, and result in poorer resolution.

The camera types you use can range from a GoPro to a high-end SLR. While you can get more detail and more control from an SLR, action cameras can produce very good results, particularly in well-lit clear water. The image capture technique just needs to be methodical to ensure sufficient coverage, and again this is detailed in the ‘how to’ guide above. To analyse the models quantitatively, there are a range of paid and open-source software types available. While the processing aspect is straight forward and can be mostly automated, the analysis needs training. However, the models can be analysed in commonly used software tools such as ArcGIS, or using open-source software, which are typically well documented. As a final point, if you wanted to just use the technique for display/educational purposes, there are programmes available which can automatically process your online, mostly at no cost.

Improving MPA Management

Webinar: The Science of Large Marine Protected Areas

The Science of Large Marine Protected Areas

The final seminar of 2020 looks at the science for large marine protected areas. Experts from across the world will discuss the role science plays in protecting the marine environment and how science can be used to inform and improve management of large marine protected areas across the world.

Due to technical difficulties during the live seminar, you can find the individual talks available from our panel of experts below.

Please do send any questions you have to info@marine.science and we will aim to get answers to you within a week.

Sebastián Yancovic Pakarati (Universidad Autónoma de Madrid) – Rapa Nui (Easter Island) Marine Protected Area

Prof. Jessica Meeuwig (University of Western Australia) – Documenting the Status of Ocean Wildlife in the Big Blue: Implications for Marine Parks

Prof. Graeme Hays (Deakin University) – The British Indian Ocean Territory (BIOT) Marine Protected Area: Conservation Gains and Key Challenges

Prof. Julia Baum (University of Victoria) – Climate change and MPAs: Insights from a Remote Reef

Coral Reefs

Webinar: Rats, Seabirds and Reefs – Holistic Approaches to Island Restoration

Rats, Seabirds and Reefs: Holistic Approaches to Island Restoration

On Tuesday 15^th September, the first of a new series of marine science seminars was held online. The session, “Rats, Seabirds and Reefs: Holistic Approaches to Island Restoration” featured an international scientific panel chaired by Professor Heather Koldewey.

A recording of the seminar is now available to watch here:

Below are answers to some of the remaining questions which there wasn’t time to answer during the live session.

What is our current understanding of how higher nutrient levels around rat free islands influence coral bleaching susceptibility in the Chagos Archipelago?

Casey Benkwitt: In lab studies, higher natural nutrient levels (like those from seabirds or fish) have been shown to reduce coral bleaching susceptibility. But, our field surveys in the Chagos Archipelago from before versus ~3 years after the 2015/2016 mass bleaching event did not show increased coral resistance around rat-free islands (i.e., coral loss was similar around rat-free and rat-infested islands). There are a few possible explanations for this difference between lab and field studies – one is that seabird nutrients reduce bleaching susceptibility during less extreme heat waves, but the 2015/2016 event was so intense and prolonged that it overpowered any benefits of seabird nutrients. Even though resistance wasn’t higher around rat-free islands, we’re now looking at whether reefs around rat-free islands recover more quickly, which is possible given the high cover of CCA and high biomass of herbivores near these islands. If you want more info, see Benkwitt et al. 2019 in Global Change Biology where we answer this question in detail!

Do you think there could be a carrying capacity of seabird populations in the Chagos archipelago based on fish productivity in the open ocean in which they can feed. i.e. could recovery of seabird numbers also be limited by food availability?

Pete Carr: A good question that has not been answered anywhere in the world regarding seabird recovery to the best of my knowledge. I suspect there is a prey availability carrying capacity cap, other top predators in different ecosystems most certainly are. It would be an interesting question to try and answer. With the methodology from my talk and the data I have, we could calculate the maximum number of breeding pairs if all islands were cleared of rats and rewilded to option C (the real time rewilding to savanna and native forest). I am guessing there are papers giving food consumption by seabirds (e.g. Danckwerts et al, 2014 for WIO). So you could get an order of magnitude of the prey needed. How one could calculate if there is that amount of prey available in Chagos is not a question I could answer. Be nice to think about it though.

Which of the three models presented would be the most practical in terms of cost effectiveness and value to the ecosystem?

Pete Carr: Based upon Casey’s talk (and Graham et al., 2018), that proves the cross-ecosystem benefits of seabird islands, plus, maximising breeding numbers of seabirds that could possibly be a source for depleted seabird populations elsewhere in the Indian Ocean, it would be logical to go for the highest totals – Option C. Option A did not restore a seabird-driven ecosystem (92% of island not being available to breeding seabirds because it is abandoned plantation) and therefore is not a viable rewilding option. Option B cannot be achieved in reality as I said, one cannot create wetlands on porous coral or, beach in an environment where there are “shifting sands” depending on prevailing winds and tides – and is not necessary because RSF graphs proved and the pie charts demonstrated we only need (and can only) create two habitats, savanna (read open areas) and native forest. Not so much a true CBA but a logical decision making process.

In Kenya, the government banned the use some chemicals used to eradicate the Indian House Crows which are believed to be a threat to other indigenous birds which they feed on within Mombasa Island and along other cities in the coastline. Is there an effective way of eradicating the crows without posing any danger within the community where they mostly feed?

Sarah Havery: Without knowing the specific details it is difficult to suggest whether eradication is possible or not – given the location it is likely that long-term control to reduce the population would be the most feasible approach. There have been some successful bird eradications from islands in the Seychelles, which I believe was achieved by shooting.

Breeding success studies are ongoing across Seychelles for several species, as expected there is lower breeding success on islands with rats but we also have population decline on an island with no rats. Restoration will/should lead to seabird population increase but other factors may also interfere with population recovery, like food availability. Have you been investigating this in the Chagos Archipelago? Are there breeding success studies for seabirds on the Chagos Islands?

Pete Carr: We are not investigating food availability (but suspect as a result of this webinar it may be researched in the future and see above). Please read Carr et al., 2020 in Bird Conservation International for the latest assessment on breeding seabirds.