Throughout the GLOMAC-project, we successfully developed a regional-scale study for the South-African mangrove range limit, that, for the first time, integrates a novel high-resolution (1/48° × 1/48°) mangrove dispersal model and data-informed habitat suitability estimates. This study was published in the high-profile journal Journal of Ecology (IF2021 = 6.38) accompanied by a press release. This part of the project was completed in collaboration with colleagues from the Nelson Mandela University (NMU, South Africa), the University of the Western Cape (UWC, South Africa), and the Moss Landing Marine Laboratories (MLML, California; GLOMAC partner). The study suggests that by 2050, nine of the 31 estuaries where mangroves grow today will become unsuitable for these plants and six additional estuaries could be added where mangroves do not currently grow. Moreover, the study provided evidence of a previously unknown mangrove forest, which was later confirmed by a field visit by colleagues in South Africa.
The projects attracted several collaborations. Insights regarding the environmental factors and processes that determine patterns of mangrove propagule dispersal and population connectivity were combined in 4 collaborative studies with Prof. dr. em. Ludwig Triest, an expert in (population) genetics. Results from these studies were disseminated in the peer-reviewed journals Biological Conservation (IF2020 = 5.991) Scientific Reports (IF2020 = 4.380) Frontiers in Marine Science (IF2020 = 4.912) and Frontiers in Conservation Science (IF2021 not yet available), as well as to the broader public via a press release. Collectively, these studies improved insight into the distribution of ecologically important mangroves in the Western Indian Ocean.
Part of the proposed work had to be postponed due to the unforeseen global Covid-19 pandemic and its implications on international travelling and institution-specific regulations and precautions. The applicant has taken quick action and developed a novel global-scale and innovative study that is at the core of the 'GLObal-scale interactions between MAngrove forests and Climate (GLOMAC)' theme, but could be realized regardless of any implications from the Covid-19 pandemic. More specifically, this study fills an important remaining gap in research that focuses on mangrove-climate interactions, and directly addresses 21st century changes in sea surface temperature, salinity, and density for coastal mangrove waters worldwide, considering implications for mangrove dispersal. In summary, this study shows substantial spatial variability in ocean property changes within and between the two major mangrove biogeographical regions, with the largest changes occurring in the Indo-West Pacific, the primary hotspot of mangrove diversity. Changes in surface-ocean water density, driven by ocean warming and freshening, are within the density range of propagules from widely distributed mangrove species, indicating the potential for threshold effects on floating time. Our results also indicate which species are most likely to be impacted by these changes. Quantifying changes in sea-surface variables and characterizing its variability across mangrove regions globally is important to better understand future dispersal dynamics and the response of mangrove forests to climate change. For example, restricted dispersal may limit the ability of mangroves to respond to disturbances and adjust their distributions in the face of climate change. The study is based on (and combines): (1) sea surface temperature and salinity data from the Bio-ORACLE database, produced from pre-processed global ocean reanalysis combining satellite and in situ observations (present condition) and different atmosphere-ocean general circulation models (future; four different RCPs); (2) sea surface density derived from temperature and salinity using the TEOS-10 non-linear thermodynamic equation of state for seawater; (3) a global mangrove extent baseline map from the Global Mangrove Watch (GMW), based on spaceborne (ALOS PALSAR) data; (4) mangrove species-specific distribution maps generated by combining GMW and IUCN data; and (5) mangrove propagule density data collected from a literature review. Results from the study were published in the high-profile journal Nature Climate Change (IF: 21.722) entitled “Mangrove dispersal disrupted by projected changes in global seawater density”. Another (Research Briefing) article on this subject has been published in the same journal (Nature Climate Change), entitled “Mangrove forests are facing challenges from global seawater density changes”.
Besides peer-reviewed publications, results from the various studies performed within the GLOMAC project have been disseminated also via oral presentations at conferences, both nationally (e.g. Belgian Royal Academy of Overseas Sciences, Marine Science Day organised by the Flanders Marine Institute) and internationally* (keynote lecture ate the Open Science Conference on Eastern Boundary Upwelling Systems - EBUS), and to the broader public through social media and multiple press releases.
*International lectures were deliberately done online to limit climate impact from international travel.
