Gema Casal

Gema Casal
National University of Ireland, Maynooth | NUI Maynooth · National Centre for Geocomputation

PhD of Remote Sensing
Postdoctoral researcher working at MaCoBioS project (www.macobios.eu)

About

31
Publications
9,138
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Introduction
Dr Gema Casal holds a degree in marine biology and a PhD on coastal remote sensing and GIS. She is interested in the application of remote sensing technologies, especially optical sensors, to study aquatic environments, especially marine and coastal ecosystems. She is currently a postdoctoral researcher at MaCoBioS project (www.macobios.eu)
Additional affiliations
January 2007 - October 2012
University of A Coruña
Position
  • PhD Student
September 2000 - June 2005
University of Santiago de Compostela
Position
  • PhD Student
Description
  • Degree in Marine Biology

Publications

Publications (31)
Article
Full-text available
As an island nation, Ireland needs to ensure effective management measures to protect marine ecosystems and their services, such as the provision of fishery resources. The characterization of marine waters using satellite data can contribute to a better understanding of variations in the upper ocean and, consequently, the effect of their changes on...
Article
Full-text available
Coastal lagoons have been providing ecological, economic and cultural benefits for many centuries. Despite their importance, the monitoring of coastal lagoons poses numerous challenges related to their complex environmental processes, their large variability in size and their remote location, inhibiting effective management programmes. This study d...
Article
This study presents an assessment of a model inversion approach to derive shallow water bathymetry in optically complex waters, with the aim of both understanding localised capability and contributing to the global evaluation of Sentinel-2 for coastal monitoring. A dataset of 12 Sentinel-2 MSI images in three different study areas along the Irish c...
Article
Optical satellite data is an efficient and complementary method to hydrographic surveys for deriving bathymetry in shallow coastal waters. Empirical approaches (in particular, the models of Stumpf and Lyzenga) provide a practical methodology to derive bathymetric information from remote sensing. Recent studies, however, have focused on enhancing th...
Article
Full-text available
Satellite derived bathymetry (SDB) enables rapid mapping of large coastal areas through measurement of optical penetration of the water column. The resolution of bathymetric mapping and achievable horizontal and vertical accuracies vary but generally, all SDB outputs are constrained by sensor type, water quality and other environmental conditions....
Article
Full-text available
Bathymetry estimated from optical satellite imagery has been increasingly implemented as an alternative to traditional bathymetric survey techniques. The availability of new sensors such as Sentinel-2 with improved spatial and temporal resolution, in comparison with previous optical sensors, offers innovative capabilities for bathymetry derivation....
Article
Using a combination of geostatistical methods and generalized additive models (GAMs), we have analyzed the combined effect of spatial, environmental and biological factors on the density of Patella vulgata, Patella depressa and Patella ulyssiponensis, three limpet species coexisting in rocky intertidal areas of the Galician coast (NW Iberian Penins...
Article
Temporal and spatial variability of Sea Surface Temperature (SST), a key variable linked to climate change, was analysed using a continuous 34-year time series of Advanced Very-High-Resolution radiometer (AVHRR) data (1982–2015). The climatological analysis showed a significant latitudinal SST gradient; waters were warmer in the south and colder in...
Poster
Full-text available
Understanding the occurrence and movement of Harmful Algal Blooms (HABs) is a key environmental, economic and societal factor in coastal areas. The global nature and impacts of HABs requires the establishment of international programmes and a cooperative approach. Moreover, given that HAB events do not respect national boundaries, cross region netw...
Poster
Full-text available
The high dynamic and optical complexity of coastal marine areas represent a major challenge in designing a program to adequately monitor and analyse these environments. Field programs consisting of periodic in situ measurements, using traditional field instruments and sampling protocols from boats, are most often ineffective in capturing the range...
Poster
Full-text available
The diffuse attenuation coefficient (Kd) is an optical property that is used to determine turbidity, water body type classification, photosynthetic and biological processes and heat transfer in the upper ocean. Water transparency is one of the indicators used to determine the status of a water body in eutrophication assessments. It is used in monit...
Article
Full-text available
Landsat 8 is the first Earth observation satellite with sufficient radiometric and spatial resolution to allow global mapping of lake CDOM and DOC (coloured dissolved organic matter and dissolved organic carbon, respectively) content. Landsat 8 is a multispectral sensor however, the number of potentially usable band ratios, or more sophisticated in...
Article
Full-text available
Many lakes in boreal and arctic regions have high concentrations of CDOM (coloured dissolved organic matter). Remote sensing of such lakes is complicated due to very low water leaving signals. There are extreme (black) lakes where the water reflectance values are negligible in almost entire visible part of spectrum (400-700 nm) due to the absorptio...
Conference Paper
Full-text available
A database of Sea Surface Temperature (SST) from 1982 to 2015 and Chlorophyll-a (Chl-a) from 1998 to 2013 have been generated for Irish coast. Monthly averages of both variables have been analysed to study their spatial and temporal trends in each ICES Division surrounding the country. SST presented a clear latitudinal gradient with warmer waters i...
Article
The Marine Institute, Ireland, runs a suite of operational regional and coastal ocean models. Recent developments include several tailored products that focus on the key needs of the Irish aquaculture sector. In this article, an overview of the products and services derived from the models are presented. A shellfish model that includes growth and p...
Conference Paper
Full-text available
The use of remote sensing has increased greatly in recent years due to technological advances and its advantages in comparison with traditional methods. In the case of Ireland however the use of these techniques is not well established and only 17% of remote sensing studies are related to marine and coastal environments. As a first step, and taking...
Article
Full-text available
The use of remote sensing is well established to map coastal environments due to its advantages with regard to traditional field methods. Among these advantages, it can be mentioned that these techniques are non-invasive, allow studying large areas, mapping inaccessible zones as well as provide a repetitive cover of a target area. However, despite...
Article
Full-text available
Rı´a de Vigo and Rı´a de Alda ´n have high biological richness that is reflected in the number of environmental protection areas like the Atlantic Islands National Park and five places of community interest. Benthic algal communities play an important role in these ecosystems due to their ecological functions and support a great part of this biolog...
Article
The term remote sensing is related to the action of obtaining information about an object, area or phenomenon without a direct contact. Over time this term has become increasingly important due to technological advances until becoming a technique of obtaining information, key in many and different fields. However, especially in Spain, the informati...
Article
Introducción El término teledetección o percepción re-mota tiene su origen en el término inglés «re-mote sensing», utilizado por primera vez en 1950 (Walter, 2006). La teledetección, podría definirse como la ciencia o el arte de adqui-rir información sobre un objeto, área o fenó-meno a través de los datos adquiridos me-diante un dispositivo que no...
Article
The ecological importance of benthic macroalgal communities in coastal ecosystems has been recognised worldwide and the application of remote sensing to study these communities presents certain advantages respect to in situ methods. The present study used three CHRIS-PROBA images to analyse macroalgal communities distribution in the Seno de Corcubi...
Article
Remote sensing has become an increasingly used technique for the thematic mapping of large marine areas. In recent years, many researchers have successfully applied these techniques in different places for benthic mapping in clear waters; however, areas with turbid waters present important limitations that are gradually being solved by recent techn...
Article
Full-text available
The invasive algae Sargassum muticum in the Iberian Peninsula competes with other native algae with important ecological value. The development of new methodologies are necessary in order to evaluate and monitor efficiently the spread of the S. muticum. The aim of this project is to validate the use of hyperespectral images to map S. muticum forest...
Article
Full-text available
The shoreline, defined as the contact limit between emerged and oceanic surface, is a key geographic limit for any study developed in the littoral zone. Although there is a certain degree of consensus in its definition, it gives rise to a multitude of specific criteria for its delimitation depending on the indicator, the source of information used...
Article
The shoreline, defined as the contact limit between emerged and oceanic surface, is a key geographic limit for any study developed in the littoral zone. Although there is a certain degree of consensus in its definition, it gives rise to a multitude of specific criteria for its delimitation depending on the indicator, the source of information used...
Article
Full-text available
The shoreline, defined as the contact limit between emerged and oceanic surface, is a key geographic limit for any study developed in the littoral zone. Although there is a certain degree of consensus in its definition, it gives rise to a multitude of specific criteria for its delimitation depending on the indicator, the source of information used...

Projects

Projects (3)
Project
A special issue of Remote Sensing (ISSN 2072-4292). This special issue belongs to the section "Remote Sensing Image Processing". Deadline for manuscript submissions: 15 November 2022. Dear Colleagues, About 71% of the Earth's surface is water-covered, and the oceans hold about 96.5% of the Earth's water volume. Aquatic environments have a direct interference with society. It was estimated that around 39% of the world population live within 100 km of the marine coastline, and 90% live within 10 km of a freshwater body. However, until today only a small fraction of the subaqueous environments have been mapped in 3D, despite the need for better knowledge of these ecosystems which are pressured by anthropogenic activities such as habitat destruction, marine pollution, damage of cultural heritage, navigation and the increasing demand for offshore energy and resources. On the other hand, natural factors enhanced by climate change effects (e.g. storms, flash floods, sea level rise, coastal erosion, harmful algal blooms) have also an important influence, especially in coastal environments. With the advent of modern remote sensing techniques (e.g., seismic reflection profiling, aerial imagery, satellites, LiDAR), researchers have now gained the ability to effectively interpret and map large portions of these dynamic changing environments. Summing up the above, accurate bathymetric and seafloor mapping are a key element during coastal and offshore studies and engineering applications, sedimentary processes, hydrographic surveys and hydrological studies as well as archaeological mapping and biological research. This Special Issue focuses on remote sensing, proximate and in-situ instrumentation, data processing and machine learning, bathymetric and seafloor mapping, water quality and pollutant detection applications in aquatic ecosystems, including the following topics: Airborne bathymetric mapping for shallow waters (two-media photogrammetry, spectral based bathymetry from UAV imagery etc.) Satellite Derived Bathymetry mapping for shallow waters Large-scale bathymetric mapping applications (i.e. ESA’s Sentinel-2 Coastal Charting Worldwide project, NOAA’s Deep ocean seafloor etc.) Remote Sensing for water quality (chlorophyll, turbidity, harmful algal blooms, etc.) Time series analysis/change detection Marine litter detection and tracking from UAV and satellite platforms Wave models for nearshore and surfzone bathymetry Water surface levels mapping Advances in Airborne and UAV-borne Laser Hydrography (LiDAR) Underwater Mapping using SONAR Fusion of hybrid bathymetric data (LiDAR, SONAR, SDB, Multimedia photogrammetry etc.) Machine and Deep Learning approaches for improved data processing techniques (refraction correction, object detection, seabed image and point cloud classification, semantic segmentation, etc.) Underwater mapping using ROVs, AUVs and Unmanned Surface Vehicles (USV) Dr. Panagiotis Agrafiotis Dr. Gema Casal Dr. Gottfried Mandlburger Dr. Konstantinos Karantzalos Dr. Dimitrios Skarlatos Guest Editors
Project
The overall objective of MaCoBioS is to ensure effective and integrated management and conservation strategies for European marine coastal ecosystems to face climate change. To address this overall objective and the expected impacts of the call, a set of specific objectives (SOs) has been determined: SO1: Develop new empirical models on the interaction between climate change, biodiversity, functions and services in marine coastal ecosystems along a geographical gradient from the tropics to the sub-polar regions, including the Mediterranean Sea. New ecological knowledge on the ecosystem’s condition will be incorporated in the functional modelling of marine coastal ecosystems. SO2: Establish a framework to assess the vulnerability of marine socio-ecological systems under climate change scenarios. Multiple ‘what-if’ scenarios will be tested to identify the response of marine coastal ecosystems to climate effects. The project will characterise novel indices encompassing biodiversity, ecosystems ecological condition and services provisioning along both environmental and socio-economic dimensions for a holistic assessment of socio-ecological systems vulnerability. SO3: Evaluate the effectiveness of nature-based solutions and protection measures at enhancing the resilience capacity of marine coastal ecosystems. The project will assess the effectiveness of nature-based solutions and protection measures to preserve and/or increase biodiversity together with human well-being. These nature-based solutions will be tested against their capacity to ensure the integrity of marine coastal ecosystems facing multiple stressors and the delivery of ecosystem services to mitigate climate change threats. SO4: Provide evidence-based guidance for marine policy formulation and innovative research pathways. Project results on the inter-relations between climate change, biodiversity and ecosystem services will support policymakers to develop appropriate and cost-effective nature-based solution strategies and thus meet the targets of EU strategies on Biodiversity and Climate Change as well as other international commitments. They will furthermore lead to the elaboration of innovative research orientations for improving the implementation of nature-based solutions.
Project
The HyspIRI ASG was established to support the HyspIRI coastal and inland aquatic remote sensing community, compiling community input regarding data products, science and applications to formulate recommendations and guidance to NASA and the HyspIRI mission. Established in 2012 through support by NASA HQ and Goddard Space Flight Center, the ASG reports to the HyspIRI Steering Committee and intefaces with the HyspIRI Science Study Group (SSG). The ASG has grown to 80+ participants, affiliated with international and domestic institutions, including government, university, research or application organizations. The ASG continues as a community of practice, promoting and advancing the coastal and inland sciences by voicing community requirements to aquatic remote sensing resource providers. If you are interested in participating in the HyspIRI ASG, please contact Kevin Turpie (kevin.r.turpie@nasa.gov).