Integrating remote sensing imagery analysis with GIS: new perspectives for the Territories – South Atlantic region.

By iLaria Marengo

 In the South Atlantic region the use of remotely sensed images in environmental analyses should be considered more often. A couple of research projects are going to begin soon: one aims at using Landsat imageries to identify giant kelp in the sea surrounding the Falkland Islands. The project will be carried out with the support and expertise provided by the Welsh consultancy group Environment Systems. Freely available Landsat imageries and e-cognition (proprietary software) will be employed for the analyses and as a part of the project training will be provided to SAERI staff in order to acquire more confidence and skill in remotely sensed image processing and analysis.

The second project, led by the marine team in Saint Helena, includes the use of side scan sonar (starfish device) techniques to gather imageries, using acoustics, of the seabed in inshore waters around the island. The images, once analysed, should provide sound baseline information to derive, along with other data layers, n habitat map for inshore waters. An intense two day course was provided in the UK by CEFAS (Centre for Environment, Fisheries and Aquaculture Science), which delivers internationally renowned science (they have many years of multibeam and side scan sonar data collection, processing and analysis experience) and collaborative relationships with UK government, EU, NGOs, research centres and industry. Support from CEFAS will continue during the project and the process of mapping marine habitats is going to be carried out as well in Ascension and in the Falkland Islands, where a new fisheries department (Ascension) has been recently created and a new project on inshore fisheries (Falkland Islands), which is led by Dr Debs Davidson (SAERI), has just started.

The use of remotely sensed images has got two important advantages: spatially it is possible to cover large areas that with a manual survey would take long time. Temporally it is possible to have measurements of the same area at different and planned periods. Hence it is possible to detect which dynamics interest/affect a geographical area by looking at the spatial, spectral, radiometric and temporal properties of the sensor.

The integration of Remote Sensing to GIS would be advantageous for researchers working for the local communities of the South Atlantic region, however it throws up a few challenges. For example, the cost of very high resolution data (resolution <= 5 metres) and the partial coverage of free high resolution (between 5 and 30 metres) satellite images, such as Landsat, for the small and remote islands of this area of the Atlantic Ocean; the management of the amount and size of data collected; the complexity of the pre-processing phase of the overall image analysis process, which requires the use of proprietary software and high level of expertise.

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This last point is going to be addressed progressively. The goal is to build local expertise and skills in the use of Remote Sensing techniques, however initial support from external experts, such as Environment Systems and CEFAS, is essential to deliver the projects and to gain how to practically analyse remotely sensed data.

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Climate Change Institute on the Black Tarn, Mt. Usborne

By Dr Brenda Hall, Climate Change Institute, University of Maine

Science Objectives:

The goal of our project is to examine glacial deposits in and around cirques at Mt. Usborne in order to gain a better understanding of the glacial and climate history of the Falkland Islands.

Black Tarn

The Black Tarn, Mt. Usborne, East Falkland

Specific Activities Conducted:

From March 16-19, 2014, a field party of three carried out glacial geologic field work in the Black Tarn area of Mt. Usborne. Field members consisted of Drs. Brenda Hall and Thomas Lowell, both from universities in the United States, and Mr. Antony Smith of Discovery Falklands, who provided logistics and a wealth of local knowledge. The party arrived at a camp site ~750 m from the Black Tarn on March 16 and was able to spend the afternoon carrying gear to the pond and making a bathymetric map (Fig. 1). The map was constructed using a portable depth sounder and by making transects across the lake in an inflatable row boat. Maximum depth recorded was ~10 m. This was less than indicated previously (McAdam and Roberts, 1981, Falkland Islands Journal, p. 23-28) by ~ 3 m, but no deeper area could be found. During this time, the field team also made preliminary observations on the glacial geology surrounding the tarn.

On March 17, the remaining gear was carried to the field site and Drs. Hall and Lowell began coring. A piston coring system was set up from the inflatable boat anchored over the deepest part of the pond. Briefly, this consisted of a polycarbonate tube with a piston that moved up the tube as it was pushed into the mud. The piston provided suction that kept sediments in the tube and allowed recovery. The corer was deployed using a rope. The initial coring drive was successful and a little over one meter of sediment was recovered (Fig. 2). This sediment shows some structure and changes in both color, composition, and grain size and will be the subject of future reports. Without laboratory analysis, it is impossible to say much for certain, but it seems as if the sediments record several wet and dry periods, the timescale of which will become clear as analyses progress. We extruded the core and took subsamples for analysis. We then attempted to take a second meter of core as we had not hit bedrock with the first drive. However, this attempt did not prove successful. We penetrated to two meters depth, but the sediments did not remain in the tube when it was pulled out. This is due mostly to the fact that we needed a different type of equipment than we had with us. The one previous coring trip to the area in the 1970s (McAdam and Roberts, 1981) had retrieved only 45 cm of sediment before meeting refusal, so we had not expected such thick sediment sequences. In the future, bringing a different type of equipment would allow us to recover this sediment and a longer climate record.

On March 18, high winds prevented us from working on the lake. We remained on shore and sampled sediments immediately adjacent to the lake using the same piston core technique. We were able to penetrate nearly three meters and retrieve silt identical to that from our lake core. This core also was subsampled. On March 19, due to increasingly bad weather and the rapidly deteriorating ground on the route out, we packed up camp and returned to Stanley.In general, except for the first day, weather conditions were wet and at freezing. Ground conditions for accessing the site by Land Rover were much worse than anticipated and a function of a rather wet March. Despite these issues, we were able to camp within a short walk of the tarn and were able to meet our scientific goals. We are excited, because there proved to be a lot more to the Black Tarn record than expected based on previous work. Our task now is to analyze the samples, particularly for radiocarbon dating, to begin to assign a timeline to the changes in sediment types that we see in the cores. At present, our best guess is that these cores span time on the order of thousands to tens of thousands of years. Samples have been submitted to the accelerator laboratory for radiocarbon dating, and we expect results in about two months.

Balck Tarn Bathymetry

 

Fig. 1. Bathymetry of the Black Tarn obtained by repeat transects with an electronic depth sounder.

 

 

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Fig. 2. Core BT-14-1, from the Black Tarn, consisting of 1.2 m of sediment.  From the base, the sequence consists of gray clay overlain by moss, overlain in turn by a thick layer of tan-gray silt. This is overlain by moss and then by a sticky gray silt layer. The entire sequence is capped by stiff, orange, sandy silt.

 

 

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Blog Entry from Alexandra Mystikou

This is my third visit to the Falkland Islands. This time I am based at SAERI (Stanley) for two months working on taxonomic issues of seaweed species from the Falkland Islands and South Georgia.

In the past our team (Professors Frithjof Kuepper and Pieter van West from the University of Aberdeen, Dr Aldo Asensi from the National Museum of Natural History in Paris, Alexandra Mystikou, who is a joint PhD student between the University of Aberdeen and the South Atlantic Environmental Research Institute, and Melina Marcou from the Dept. of Fisheries and Marine Research, Cyprus) has conducted four expeditions around the Falkland Islands sampling live isolates of macroalgae (seaweeds). Our investigations focus on the molecular taxonomy, ecology and physiology of macroalgae of the Antarctic and Subantarctic regions. During our expeditions we preserve samples of seaweeds for molecular identification, create herbarium specimens and keep cultures of live isolates.

I joined SAERI in October 2012 as a PhD student, co-supervised by Prof. Frithjof Kuepper, Prof. Pieter van West (University of Aberdeen) and Dr Paul Brickle (South Atlantic Environmental Research Institute). My research explores the seaweed biodiversity around the Antarctic Convergence in the South Atlantic and is jointly funded with a scholarship from the University of Aberdeen and the Falkland Islands Government.

The seaweed biodiversity around the Falklands remains only partially explored. Since the pioneering work of Skottsberg in the early 20th century, few phycologists have visited the islands. More specifically, there are significant gaps in the understanding of the Falklands’ deep-water brown algal flora – mainly due to the reason that none of the earlier explorers have dived here.

The two previous expeditions exceeded our expectations as two likely new species of brown epiphytes on the two kelp genus that occur at the Falkland Islands (Macrocystis and Lessonia) have been discovered. Furthermore, three new records of species that potentially have not been recorded before were made. Another significant finding was the rediscovery of Cladochroa chnoosporiformis which had not been seen anywhere in the world for around 100 years.

Witnessed by many in the Falkland Islands is the “red sand” on various beaches, the cause of which has remained a bit of a mystery. After microscopic observations we hypothesize that this might be due to a mass proliferation of a unicellular red alga (e.g. of the group Porphyridiophyceae). In our explorations, we managed to cover large areas both in East and West Falkland, sampling seaweeds by scuba diving.

In another line of research we explore the ecology of the seaweed communities around the Falkland Islands and South Georgia. In order to identify the seaweed species that form the studied communities we are using PhotoQuad™ software, which is a custom software for advanced image processing of 2D photographic quadrat samples, dedicated to ecological applications (Trygonis & Sini, 2012). The two areas from the Falklands that have been selected are the Jason Islands at the north-western extremity of West Falkland and Beauchêne Island, the southernmost point of the Falkland Islands. These areas have been selected because of their peculiar geographical position, in order to compare the structure of their seaweed communities. The Antarctic Circumpolar Current splits into two main northward streams skirting the Falkland Islands from west and east (Arkhipkin et al., 2013). As a result, there are variations between the productivity and the temperature between the two areas which cause variability between the species composition of the two studied sites.

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100 random points at PhotoQuad of South Georgian underwater quadrat photo (Photo credit: SMSG)

The structure of a community of species points out the ecological status of an area. We are comparing the number of single species per genus and per family between the three studied areas (Jason Islands, Beauchêne Island and South Georgia) where the temperature and the productivity are affected differently by the Antarctic Circumpolar Current. The evolutionary relationships among coexisting species may provide further indicators of the ecology of the habitat. Taxonomic distinctness of a community can be studied by a combination of phylogeny and community structure.
In the present study we are investigating the phylogenetic structure of the community assemblages by identifying 100 and 200 random points per underwater quadrate image (approximately 300 images per area) and then comparing the genus/species and species /family numbers between the three studied areas. The quadrat photos have been taken at different depths for each area. We are hoping that the outcome from this study will contribute to the knowledge about the ecology of the seaweed habitats of the Falkland Islands and South Georgia and help us understand better the drivers that lead the communities to structure differently.

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 How many seaweed species can you spot in the picture? (Coraligenus habitat from South Georgia) (Photo credit: SMSG)

Many thanks to the Shallow Marine Surveys Group (SMSG) for collecting and offering kindly to me all the photographic quadrat samples from Jason Islands, Beauchene Island and South Georgia as well as Dr. Paul Brickle and Dr. Paul Brewin for the project (ecology of the seaweed communities around the Falkland Islands and South Georgia) support and guidance. I would like also to thank the South Atlantic Environmental Institute (SAERI) for accommodating and supporting always our research team.

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