Climate change in oceanwater may impact mangrove dispersal

Climate change in oceanwater may impact mangrove dispersal

VUB-publication in Nature Climate Change considers for the first time effects of climate-driven changes in seawater on mangrove forests

International research led by Dr. Tom Van der Stocken of the VUB Biology Department examined 21st century changes in ocean-surface temperature, salinity, and density, across mangrove forests worldwide. The study suggests that changes in surface-ocean density may impact the dispersal patterns of widely distributed mangroves species, and more likely so in the Indo-West Pacific region, the primary hotspot of mangrove diversity. The study is published in the renowned Nature Climate Change.

“Climate change affects sea-surface density via changes in temperature and salinity. Since propagules of widely distributed mangroves species have densities near that of seawater, changes in ocean density hold implications for oceanic dispersal of mangroves. Whether mangrove propagules float or sink depends on the difference between the densities of the propagules and that of the surrounding water.” says Tom Van der Stocken, Marie Skłodowska-Curie Postdoctoral Scholar at Vrije Universiteit Brussel, and research affiliate at the NASA Jet Propulsion Laboratory. ​
It is expected that warming winter temperatures and sea level rise will impact the distribution of these carbon-rich forests, but changes in surface-ocean properties might also influence distributional patterns through dispersal.”

Mangroves are highly productive intertidal forests that occur along tropical, subtropical, and some temperate coasts. They support a broad variety of ecosystem goods and services and have an important place on the international climate mitigation and adaptation agenda. However, at the same time, these intertidal forests are strongly impacted by human activities and subjected to climate-driven changes in the marine, terrestrial and atmospheric processes to which they are tightly linked. While previous studies have focused on the potential impact of sea-level rise, altered precipitation regimes, and increasing temperature and storm frequency on mangrove ecosystems, the potential effects of climate-driven changes in seawater properties had not been considered.

Van der Stocken: “This is surprising, as the ocean is the primary dispersal medium of this ‘sea-faring’ coastal vegetation and dispersal is a key process that governs a species’ response to climate change by changing its geographical range.”

The paper, “Mangrove dispersal disrupted by projected changes in global seawater density”, is co-authored by VUB professors Bram Vanschoenwinkel and Nico Koedam, and in collaboration with the Moss Landing Marine Laboratories (MLML) and the University of California, Los Angeles (UCLA). The team made use of present and future sea-surface temperature and salinity data from the Bio-ORACLE database developed at Ghent University, and derived sea-surface density estimates from these data using the UNESCO EOS-80 equation of state polynomial for seawater.

“Our study provides evidence that the density of surface-ocean waters along mangrove forests will decrease by the end of the 21st century, and a factor of two larger in the Indo-West Pacific region than in the Atlantic East Pacific,” says Koedam.
“It is important to note that our study uses present and future environmental conditions based on monthly averages and that the actual variability in sea-surface density around these mean values could be higher than that predicted in this study,” adds Vanschoenwinkel.
Van der Stocken: “There is still uncertainty on exactly how the projected changes in seawater density will impact realized mangrove dispersal in different parts of the world and more research is needed regarding the biological response of mangroves to climate-driven changes in surface-water properties. In this study, we took advantage of marine data layers to fill this gap, and we hope that our study will help to inspire new research that will quantify the effects of changes in the properties of the ocean surface on propagule floating periods, dispersal, and connectivity.”

Publication in Nature Climate Change: Mangrove dispersal disrupted by projected changes in global seawater density

Contact:

Tom Van der Stocken

[email protected]

+32 468 47 57 77

Global map showing the change in (a) sea surface temperature (SST), (b) salinity (SSS), and (c) density (SSD) across mangrove bioregions under RCP 8.5. Changes in SST and SSS are based on present-day (2000–2014) and future (2090–2100) marine fields from the Bio-ORACLE database, from which SSD data were derived. The vertical line (19° E) separates the two major mangrove bioregions: the Atlantic-East Pacific (AEP) and the Indo-West Pacific (IWP).
Global map showing the change in (a) sea surface temperature (SST), (b) salinity (SSS), and (c) density (SSD) across mangrove bioregions under RCP 8.5. Changes in SST and SSS are based on present-day (2000–2014) and future (2090–2100) marine fields from the Bio-ORACLE database, from which SSD data were derived. The vertical line (19° E) separates the two major mangrove bioregions: the Atlantic-East Pacific (AEP) and the Indo-West Pacific (IWP).
Mangrove forest at Gazi Bay, Kenya. © Tom Van der Stocken.
Mangrove forest at Gazi Bay, Kenya. © Tom Van der Stocken.
Propagules of the mangrove species Rhizophora mucronata, a species which is very widespread in the Indo-West Pacific, possess near-seawater densities. Mangrove propagules are transported by riverine, tidal, coastal and open-ocean currents and their float-and-sink dynamics rely on the difference in density between that of the propagules and the surrounding waters. © Tom Van der Stocken.
Propagules of the mangrove species Rhizophora mucronata, a species which is very widespread in the Indo-West Pacific, possess near-seawater densities. Mangrove propagules are transported by riverine, tidal, coastal and open-ocean currents and their float-and-sink dynamics rely on the difference in density between that of the propagules and the surrounding waters. © Tom Van der Stocken.
 Mangroves thrive along coastlines of tropical, subtropical and some warm-temperate regions, and are inundated regularly by tides. © Tom Van der Stocken.
Mangroves thrive along coastlines of tropical, subtropical and some warm-temperate regions, and are inundated regularly by tides. © Tom Van der Stocken.

 

Lies Feron
Lies Feron Persrelaties Vrije Universiteit Brussel

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WE
About Press - Vrije Universiteit Brussel

Vrije Universiteit Brussel is an internationally oriented university in Brussels, the heart of Europe. By providing excellent research and education on a human scale, VUB wants to make an active and committed contribution to a better society.

The World Needs You

The Vrije Universiteit Brussel assumes its scientific and social responsibility with love and decisiveness. That’s why VUB launched the platform De Wereld Heeft Je Nodig – The World Needs You, which brings together ideas, actions and projects based on six Ps. The first P stands for People, because that’s what it’s all about: giving people equal opportunities, prosperity, welfare, respect. Peace is about fighting injustice, big and small, in the world. Prosperity combats poverty and inequality. Planet stands for actions on biodiversity, climate, air quality, animal rights... With Partnership, VUB is looking for joint actions to make the world a better place. The sixth and last P is for Poincaré, the French philosopher Henri Poincaré, from whom VUB derives its motto that thinking should submit to nothing except the facts themselves. VUB is an ‘urban engaged university’, strongly anchored in Brussels and Europe and working according to the principles of free research.

www.vub.be/dewereldheeftjenodig

 


Press - Vrije Universiteit Brussel
Pleinlaan 2
1050 Brussel