Thesis project proposal for Concours GAIA, 2025
The thesis proposal described below will shortly be open for applications as part of the GAIA doctoral school’s “concours for 2025”. The thesis project is within the MESCAL project studying the impacts of marine protected areas (MPAs) on climate change resilience in coastal fish populations of East Africa.
Essential information
- Doctoral project title: Marine connectivity in a network of marine protected areas (MPAs) as a key factor for assuring climate change resilience in the marine ecosystems of East Africa
- Keywords: Marine spatial planning (MPAs); Global change; Marine connectivity; Larval dispersal modeling; Genetic diversity; Fish physiology
- Thesis director: David M. Kaplan
- Thesis co-director: Christophe Lett
- Host institution of thesis project: Sète laboratory of the MARBEC mixed research unit (UMR)
- Financing: Bursary from GAIA doctoral school of the University of Montpellier with a scientific budget provided by the MESCAL research project
Summary of thesis project
Climate change threatens the long-term sustainability of marine ecosystems. Although Marine protected areas (MPAs) are recognized as an effective tool to protect harvested species and biodiversity, they were generally not explicitly designed to increase the resilience of marine ecosystems to climate change. A major open issue is whether and by what mechanisms current and future MPAs can simultaneously buffer intraspecific (genotypes and phenotypes) diversity and community diversity against climate change, thereby enhancing sustainability of marine ecosystems. Marine connectivity via larval dispersal plays a pivotal role in these processes by potentially ensuring that individuals from climate or fishing refugia can repopulate impacted areas. These questions are particularly important in the Western Indian Ocean (WIO), given that warming and fishing exploitation in this region are increasing at an alarming rate. In the WIO, fish support key ecological functions and are the primary source of protein and income for coastal communities. Importantly, it has recently been shown that fish in MPAs tend to have higher aerobic scope than individuals in fished areas, suggesting that reserve individuals may be more tolerant of extreme temperature events caused by climate change and, therefore, more likely to survive and adapt to future climate change.
To test these hypotheses, this thesis project will use larval dispersal models to examine how exchange of larval fish from protected to exploited areas can increase overall climate change resilience of exploited marine fishes along the East African coast by the exchange of individuals with traits associated with climate change resilience, which are expected to be more prevalent within MPAs. The PhD will be carried out within the wider MESCAL project, an international, ANR- and AFD-funded project with a 1 million € budget. MESCAL will work on three exploited East African fish species and includes collaborators from Kenya, Tanzania, Mozambique and South Africa, in addition to France. As a basis for the thesis project, the MESCAL project and associated research projects (e.g., BRIDGES) will develop ocean dynamics simulations including climate change impacts and collect data on the links between physiological traits related to climate resilience and genotypes to identify heritability of climate change resilience in the three target species. The thesis student will use ocean simulations to drive larval dispersal models covering the study region. Model simulations will be carried out both ignoring fish physiological traits to assess general connectivity patterns and including differences between reserve and non-reserve areas in terms of to climate resilience, allowing us to understand in detail the extent to which reserve areas replenish genetic diversity in exploited areas, thereby enhancing climate resilience. These results will be used to provide overall assessment of the effectiveness of existing reserve networks for climate change resilience and to identify future priorities for conservation that mitigate for the impacts of climate change.
Detailed project description
Objectives
The objectives of this PhD project are to understand the value of marine protected areas (MPAs) along the coast of East Africa for assuring the resilience of coastal marine fish populations to climate change via the export of more genetically diverse, and therefore more physiologically diverse, individuals from MPAs via larval dispesal. This work will assess the value of existing MPAs as a bulwark against the large predicted changes in oceanic conditions in the region over the next 80 years, as well as identify additional spatial zones that may merit protection in the future to stabilize marine communities and assure food production and livelihoods in the region.
Context
Climate change threatens the long-term sustainability of marine ecosystems (Hoegh-Guldberg et al. 2017). Although Marine protected areas (MPAs) are recognized as an effective tool to protect harvested species and biodiversity, they were generally not explicitly designed to increase the resilience of marine ecosystems to climate change (Bates et al. 2019). In this context, a major issue that remains to be explored is whether and by what mechanisms current and future MPAs can simultaneously buffer intraspecific (genotypes and phenotypes) diversity and community diversity against climate change, thereby enhancing sustainability of marine ecosystems. Marine connectivity via larval dispersal plays a pivotal role by potentially ensuring that individuals from climate or fishing refugia can repopulate impacted areas (Balbar & Metaxas 2019). These questions are particularly important in the Western Indian Ocean (WIO), given that warming and fishing exploitation in this region are increasing at an alarming rate (Roxy et al. 2016). In the WIO, fish support key ecological functions and are the primary source of protein and income for coastal communities (Obura et al. 2017), and the creation or expansion of MPAs is a promising mitigation measure for the negative impacts of climate change on fish stocks. Importantly, it has recently been shown that fish in MPAs tend to have higher aerobic scope than individuals in fished areas, suggesting that reserve individuals may be more tolerant of extreme temperature events caused by climate change and, therefore, more likely to survive and adapt to future climate change (Duncan et al. 2019).
To address these issues, this thesis project will use larval dispersal models to examine how exchange of larval fish from protected to exploited areas can increase overall climate change resilience of exploited marine fishes along the East African coast via exchange of traits associated with climate change resilience that are more prevalent within MPAs. The PhD will be carried out within the wider MESCAL project, an international, ANR- and AFD-funded project with a 1 million € budget. MESCAL will work on three exploited East African fish species (Lutjanus rivulatus, blubberlip snapper, a cosmopolitan species found all along the East African coast; Diplodus capensis, blacktail, a warm-temperate species found in South Africa & Mozambique; Lutjanus fulviflamma, dory snapper, found primarily in Kenya and Tanzania) and includes collaborators from Kenya, Tanzania, Mozambique and South Africa, in addition to France. One of the major objectives of MESCAL is to collect data on fish physiological traits linked to climate change resilience and genetics information for these three fish species inside and outside MPAs in East Africa to assess the value of protection and identify specific genes that are associated with climate change resilience. The proposed thesis project will have the key role of understanding how dispersal can transfer highly resilient individuals from MPAs to surrounding areas (Brochier et al. 2009, Andrello et al. 2013, Muller et al. 2023), thereby maintaining climate change resilience among fished populations. This information will contribute to assessments of the robustness of regional MPAs networks to climate change (see, e.g., Kaplan et al. 2009).
Methodology
The overall approach will be to use the individually-based, lagrangian larval dispersal modeling tool Ichthyop (Lett et al. 2008) to simulate the dispersal of individuals with different genotypes and/or phenotypes based on their conservation status (i.e., reserve or non-reserve point of larval production) from habitat areas along the coast of East Africa to assess the contribution of MPAs to maintaining the genetic biodiverisity and climate change resilience of exploited fish populations. First, the MESCAL project and associated research projects (e.g., BRIDGES) will develop ocean dynamics simulations including climate change impacts and collect data on the links between physiological traits related to climate resilience (e.g., aerobic scope, temperature tolerances, growth rates) and genotypes to identify heritability of climate change resilience in the three target species. Ocean simulations will initially be used by the student to drive Ichthyop larval dispersal simulations ignoring climate change resilience to understand general patterns of connectivity in the study region now and into the future building off of prior work (e.g., Lett et al. 2023, Muller et al. 2023). Then differences between reserve and non-reserve areas in the prevalence of traits favorable to climate resilience will be included in simulations allowing us to examine the extent to which reserve areas replenish genetic diversity in exploited areas. These results will be used to provide overall assessment of the effectiveness of existing reserve networks for climate change resilience (e.g., conceptually similar to Kaplan et al. 2009). Finally, reserve network optimization algorithms (Watts et al. 2009, e.g., Jacobi & Jonsson 2011) will be adapted to identify future priorities for conservation that mitigate for the impacts of climate change.
Expected results
The thesis project will produce simulations of larval dispersal patterns for the three project study species along the East African coast both for the current time period and the end of the century based on climate change scenarios. These results will allow us to analyze and constrast connectivity patterns over time, between species with different life histories and between individuals with different levels of resilience to extreme temperature fluctuations. Connectivity data will be used to assess the effectiveness of current and potential new MPAs as bulwarks against the impacts of climate change.
Scientific, material and financial context of the project
The student will be based at the Sète laboratory of the UMR MARBEC, a large, interdisciplinary marine science laboratory in the Occitanie region of France with facilities in Sète, Montpellier and Palavas. MARBEC has over 300 members working in all areas of marine science, including oceanographers, larval dispersal modelers, geneticists, physiologists and computer scientists that will provide invaluable assistance to the thesis project. Critically, MARBEC has access to multiple high-performance computing clusters capable of running the larval dispersal models that will be central to the thesis project.
The project will also require collaboration with MESCAL international partners, including visits to the study region and potential participation in MESCAL fieldwork and data collection. Any such travel will be funded by the MESCAL project and carried out in close collaboration with regional MESCAL project participants to assure the success of the work and the security of the student.
International context
The MESCAL project involves 10 funded partners, 5 collaborating partners and at least 21 individual participants from 5 countries (France, Kenya, Tanzania, Mozambique and South Africa). The doctoral student will be expected to interact and collaborate extensively with these partners. This interaction will both give the student extensive international exposure, as well as provide opportunities to present work along with other MESCAL project participants at regional scientific fora, such as the annual meeting of the Western Indian Ocean Marine Science Association (WIOMSA). Furthermore, as the topic of climate change resilience and adaptation in exploited marine ecosystems is of wide, international interest, it is expected that the work will be published in internationally-recognized journals and that the student will have the opportunity to present the work at least one large, international marine sciences or climate change conference.
Expected collaborations
Thesis project collaborations will occur at two levels: (i) within the MARBEC laboratory itself and (ii) internationally with MESCAL project partners in East Africa. Within MARBEC, the student will collaborate with a network of oceanographers (e.g., M. Lengaigne & C. Duteil), larval dispersal modelers (e.g., D. Kaplan & C. Lett), geneticists (e.g., C. Reisser), spatial ecologists (e.g., T. Lamy & D. Kaplan), physiologists (e.g., D. McKenzie) and computer scientists (e.g., N. Barrier) to use oceanographic simulations of climate change impacts to model larval dispersal of key physiological traits for climate change resilience now and in the future, and then use this information to assess the value of existing and potential new MPAs for climate change resilience of coastal, exploited fish populations in East Africa.
The thesis project will also include international collaborators in MESCAL partner institutions who will provide both genetics and fish physiology data on the three target species and expertise on target species larval and adult life histories essential to parameterizing larval dispersal and population dynamic models.
Valorisation of project results
It is expected that project results will be openly published in respected, international scientific journals. In addition, results will be presented at pertinent regional and international scientific conferences. The MESCAL project also includes a series of consultations with regional stakeholders to understand their concerns regarding climate change and valuations of MPAs and of scientific information for making management decisions to assure the sustainability of exploited marine resources. Thesis results will directly and/or indirectly contribute to these consultations by providing essential information regarding the value of MPAs for climate change mitigation.
Candidature
Profile and skills required
The ideal student for this project will have a Masters in marine science, with exposure to statistics, computer programming and marine population dynamics. Previous use of R, Python or Matlab is highly desirable. In addition, as the project will involve collaboration with a number of French and international partners, the student must possess strong teamworking skills, including a positive attitude, professional demeanor and good communication skills. Proficiency in scientific communication and writing in English will be essential to successful integration into the MESCAL project and diffusion of thesis results. An ability to work and communicate in French is desireable, but not essential to the project.
How to apply
Though applications should ultimately be sent to the GAIA doctoral school “concours 2025”, interested candidates should initially contact David M. Kaplan following the procedure described here for an initial assessment of your aptness for the thesis and guidance on applying to the GAIA doctoral school.