Dredging in the Spratly Islands: gaining land but losing reefs

Coral reefs on remote islands and atolls are less exposed to direct human stressors but are becoming increasingly vulnerable because of their development for geopolitical and military purposes. Here we document dredging and filling activities by countries in the South China Sea, where building new islands and channels on atolls is leading to considerable losses of, and perhaps irreversible damages to, unique coral reef ecosystems. Preventing similar damage across other reefs in the region necessitates the urgent development of cooperative management of disputed territories in the South China Sea. We suggest using the Antarctic Treaty as a positive precedent for such international cooperation

The influence of vector‐borne disease on human history: socio‐ecological mechanisms

Vector-borne diseases (VBDs) are embedded within complex socio-ecological systems. While research has traditionally focused on the direct effects of VBDs on human morbidity and mortality, it is increasingly clear that their impacts are much more pervasive. VBDs are dynamically linked to feedbacks between environmental conditions, vector ecology, disease burden, and societal responses that drive transmission. As a result, VBDs have had profound influence on human history. Mechanisms include: (1) killing or debilitating large numbers of people, with demographic and population-level impacts; (2) differentially affecting populations based on prior history of disease exposure, immunity, and resistance; (3) being weaponised to promote or justify hierarchies of power, colonialism, racism, classism and sexism; (4) catalysing changes in ideas, institutions, infrastructure, technologies and social practices in efforts to control disease outbreaks; and (5) changing human relationships with the land and environment. We use historical and archaeological evidence interpreted through an ecological lens to illustrate how VBDs have shaped society and culture, focusing on case studies from four pertinent VBDs: plague, malaria, yellow fever and trypanosomiasis. By comparing across diseases, time periods and geographies, we highlight the enormous scope and variety of mechanisms by which VBDs have influenced human history

Potential impacts of climate change on agriculture and fisheries production in 72 tropical coastal communities

Climate change is expected to profoundly affect key food production sectors, including fisheries and agriculture. However, the potential impacts of climate change on these sectors are rarely considered jointly, especially below national scales, which can mask substantial variability in how communities will be affected. Here, we combine socioeconomic surveys of 3,008 households and intersectoral multi-model simulation outputs to conduct a sub-national analysis of the potential impacts of climate change on fisheries and agriculture in 72 coastal communities across five Indo-Pacific countries (Indonesia, Madagascar, Papua New Guinea, Philippines, and Tanzania). Our study reveals three key findings: First, overall potential losses to fisheries are higher than potential losses to agriculture. Second, while most locations (> 2/3) will experience potential losses to both fisheries and agriculture simultaneously, climate change mitigation could reduce the proportion of places facing that double burden. Third, potential impacts are more likely in communities with lower socioeconomic status

Thresholds in seascape connectivity: influence of mobility, habitat distribution, and current strength on fish movement

Assessing connectivity of the marine environment is a fundamental challenge for marine conservation and planning, yet conceptual development in habitat connectivity has been based on terrestrial examples rather than marine ecosystems. Here, we explore differences in marine environments that could affect localized movement of marine organisms and demonstrate the importance of incorporating them into seascape models. We link a fish-based cost surface model to simulated seascapes to test hypotheses about the effects of fish mobility, water current strength, and their interactions on functional connectivity of a seascape. Our models predict that sedentary fish should be more sensitive to habitat change than more mobile fish. Furthermore, highly mobile fish should be more sensitive to water currents than habitat change. In our models, the cost of swimming against a current (of any strength) exceeded its benefits, resulting in overall decreases in connectivity with increasing current strengths. We further hypothesized that thresholds in functional connectivity will be affected by both fish mobility and water current strength. Connectivity thresholds in the models occurred when 10–50 % of benthic habitat was favourable; below these thresholds there was a rapid increase in path cost. Thresholds were influenced by the interaction of relative habitat costs (simulated fish mobility) and habitat fragmentation: thresholds for less mobile fish (higher relative cost) were reached at lower habitat abundance when habitat was fragmented, while thresholds for mobile fish were less affected by fragmentation. Our approach suggests mobility and water current are useful indicators of connectivity in marine environments and should be incorporated in seascape models

A sedentary fish on the move: effects of displacement on long-snouted seahorse (Hippocampus guttulatus Cuvier) movement and habitat use

To understand how a sedentary fish responds to displacement and identify key habitat characteristics for that fish, we translocated long-snouted seahorses (Hippocampus guttulatus) within their natural habitat but far beyond their home range. After displacement, we located these small fish using acoustic technology and collected environmental data where we captured, released, and relocated them. Displaced fish (n = 9) moved much greater distances (max: 150 m; mean daily: 6.4–48.2 m) than expected from known home range movements and there was no evidence of homing. Seahorses varied in the specific environments they moved towards but tended to move towards environments more similar in both depth and water current speed to their original capture locations than their release locations

Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability

<div><p>Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and social systems. While there have been considerable advances in understanding the physical aspects of climate change, comprehensive analyses integrating climate, biological, and social sciences are less common. Here we use climate projections under alternative mitigation scenarios to show how changes in environmental variables that limit plant growth could impact ecosystems and people. We show that although the global mean number of days above freezing will increase by up to 7% by 2100 under “business as usual” (representative concentration pathway [RCP] 8.5), suitable growing days will actually decrease globally by up to 11% when other climatic variables that limit plant growth are considered (i.e., temperature, water availability, and solar radiation). Areas in Russia, China, and Canada are projected to gain suitable plant growing days, but the rest of the world will experience losses. Notably, tropical areas could lose up to 200 suitable plant growing days per year. These changes will impact most of the world’s terrestrial ecosystems, potentially triggering climate feedbacks. Human populations will also be affected, with up to ~2,100 million of the poorest people in the world (~30% of the world’s population) highly vulnerable to changes in the supply of plant-related goods and services. These impacts will be spatially variable, indicating regions where adaptations will be necessary. Changes in suitable plant growing days are projected to be less severe under strong and moderate mitigation scenarios (i.e., RCP 2.6 and RCP 4.5), underscoring the importance of reducing emissions to avoid such disproportionate impacts on ecosystems and people.</p></div

Spatial changes in projected suitable days for plant growth.

<p>Changes between future (i.e., the average from 2091 to 2100) and contemporary (i.e., the average from 1996 to 2005) number of days with suitable climatic conditions for plant growth under RCP 8.5 (results for all RCPs shown in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002167#pbio.1002167.s014" target="_blank">S5</a>–<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002167#pbio.1002167.s016" target="_blank">S7</a> Figs; data are provided in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002167#pbio.1002167.s002" target="_blank">S2 Data</a>). The map outline was obtained from the Central Intelligence Agency (CIA) World DataBank (<a href="https://www.evl.uic.edu/pape/data/WDB/" target="_blank">https://www.evl.uic.edu/pape/data/WDB/</a>).</p

Global average changes in projected suitable days for plant growth.

<p>These plots illustrate the global average number of suitable plant growing days relative to contemporary values. Data are provided in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002167#pbio.1002167.s003" target="_blank">S3 Data</a>.</p

Projected changes in NPP under different scenarios of emissions and human consumption of terrestrial NPP.

<p>Plots A–C show the global average change in NPP under different scenarios before (blue lines) and after (red lines) accounting for unsuitable plant growing days. Grey lines indicate the projected global human appropriation of terrestrial NPP (i.e., modern per capita appropriation of NPP multiplied by human population projections under different scenarios). Additional details are shown in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002167#pbio.1002167.s013" target="_blank">S4 Fig</a>. Data are provided in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002167#pbio.1002167.s005" target="_blank">S5 Data</a>.</p