fragmentation is a major driver of ecosystem degradation, reducing the capacity of habitats to provide many important ecosystem services. Mangrove ecosystem services, such as erosion prevention, shoreline protection and mitigation of climate change (through carbon sequestration), depend on the size and arrangement of forest patches, but we know little about broad-scale patterns of mangrove forest fragmentation. Here we conduct a multi-scale analysis using global estimates of mangrove density and regional drivers of mangrove deforestation to map relationships between habitat loss and fragmentation. Mangrove fragmentation was ubiquitous; however, there are geographic disparities between mangrove loss and fragmentation; some regions, like cambodia and the southern caribbean, had relatively little loss, but their forests have been extensively fragmented. in Southeast Asia, a global hotspot of mangrove loss, the conversion of forests to aquaculture and rice plantations were the biggest drivers of loss (>50%) and fragmentation. Surprisingly, conversion of forests to oil palm plantations, responsible for >15% of all deforestation in Southeast Asia, was only weakly correlated with mangrove fragmentation. Thus, the management of different deforestation drivers may increase or decrease fragmentation. Our findings suggest that large scale monitoring of mangrove forests should also consider fragmentation. this work highlights that regional priorities for conservation based on forest loss rates can overlook fragmentation and associated loss of ecosystem functionality.Mangroves are intertidal wetlands found along coastlines in much of the tropical, subtropical and warm-temperate world. These forests provide valuable ecosystem services including preventing erosion 1 , providing habitat for fisheries species 2 , protecting coastal communities from extreme weather events 3,4 and storing large reserves of blue carbon, thus mitigating global climate change 5 . The services provided by mangroves are threatened by anthropogenic processes including deforestation 6 and sea-level rise 7,8 . Historically, mangroves were subject to high rates of deforestation of up to 3.6% per annum 9 . However, since the turn of the millennium global mangrove deforestation rates have slowed, with annual loss rates of 0.2-0.7% 10,11 . Lower rates of loss are due to near total historical loss of forest patches in some regions, but also improved conservation practices 11 and improvements in large scale monitoring techniques that provide more accurate estimates of cover and loss than were available historically 10,12 . The majority of contemporary mangrove loss occurs in Southeast Asia, where ~50% of the remaining global mangrove forest area is located, with nations such as Indonesia, Malaysia and Myanmar continuing to show losses of 0.26, 0.41 and 0.70% per year, respectively 10 .Recently, researchers have highlighted that simply reporting mangrove total loss rates is insufficient for prioritising conservation actions 11 , if there is insufficient knowledge...

Mangroves have among the highest carbon densities of any tropical forest. These 'blue carbon' ecosystems can store large amounts of carbon for long periods, and their protection reduces greenhouse gas emissions and supports climate change mitigation. Incorporating mangroves into Nationally Determined Contributions to the Paris Agreement and their valuation on carbon markets requires predicting how the management of different land-uses can prevent future greenhouse gas emissions and increase CO 2 sequestration. We integrated comprehensive global datasets for carbon stocks, mangrove distribution, deforestation rates, and land-use change drivers into a predictive model of mangrove carbon emissions. We project emissions and foregone soil carbon sequestration potential under 'business as usual' rates of mangrove loss.Emissions from mangrove loss could reach 2391 Tg CO 2 eq by the end of the century, or 3392 Tg CO 2 eq when considering foregone soil carbon sequestration. The highest emissions were predicted in southeast and south Asia (West Coral Triangle, Sunda Shelf, and the Bay of Bengal) due to conversion to aquaculture or agriculture, followed by the Caribbean (Tropical Northwest Atlantic) due to clearing and erosion, and the This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Research into marine population connectivity (MPC)-the rate of transfer of organisms between locations-is important for our understanding of how marine systems operate as well as our ability to conserve them effectively. The large body of research in this field has never been quantitatively assessed to identify the manner in which research effort has been expended. We conducted an extensive quantitative literature review of >1000 studies and analysed the 'What?' and the 'How?' of MPC research. Publication rates increased dramatically in the mid-2000s, due to a surge of studies utilising genetic techniques and assessing larval dispersal, but studies assessing post-larval movement have not increased at the same rate. The MPC literature is dominated by bony fish, ~3 times more prevalent than the next most common taxonomic class (malacostracan crustaceans). The dispersal of some habitat-forming organisms (e.g. seagrasses, kelps) have been studied extensively (particularly corals), whereas other groups have received minimal attention (e.g. mangroves and saltmarshes). Spatially, studies have been concentrated around Europe, North America and Australia, in contrast to regions such as eastern and southern Asia and western Africa. These taxonomic, habitat and geographic biases are likely to impact our ability to predict and manage for connectivity in these systems due to the large variance in life-history traits and abiotic conditions between well-studied and under studied systems. We recommend that researchers refocus efforts towards under-studied regions, taxa and habitats to obtain a more representative understanding of the scales of connectivity and connectivity's role in maintaining populations.

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Mangroves have among the highest carbon densities of any tropical forest. These “blue carbon” ecosystems can store large amounts of carbon for long periods, and their protection reduces greenhouse gas emissions and supports climate change mitigation. The incorporation of mangroves into Nationally Determined Contributions to the Paris Agreement and their valuation on carbon markets requires predicting how the management of different land-uses can prevent future greenhouse gas emissions and increase CO2 sequestration. Management actions can reduce CO2 emissions and enhance sequestration, but should be guided by predictions of future emissions, not just carbon storage. We project emissions and forgone soil carbon sequestration potential caused by mangrove loss with comprehensive global datasets for carbon stocks, mangrove distribution, deforestation rates, and drivers of land-use change. Emissions from mangrove loss could reach 2,397 Tg CO2eq by the end of the century, or 3,401 Tg CO2eq when considering forgone carbon sequestration. The highest emissions were predicted in southeast and south Asia (West Coral Triangle, Sunda Shelf, and the Bay of Bengal) due to conversion to aquaculture or agriculture, followed by the Caribbean (Tropical Northwest Atlantic) due to clearing and erosion, and the Andaman coast (West Myanmar) and north Brazil due to erosion. Together, these six regions accounted for 90% of the total potential CO2eq future emissions. We highlight hotspots for future emissions and the land-use specfic management actions that could avoid them with appropriate policies and regulation.