Ecosystems services at risk

International audienceClimate change is threatening coral-reef-associated ecosystem services and people's well-being. Addressing direct and indirect coral reef stressors while developing pathways towards recovery and adaptations could mitigate negative impacts, especially in coastal developing countries

Multiscale determinants of social adaptive capacity in small-scale fishing communities

Climate change is expected to reinforce undesirable social and ecological feedbacks between ecosystem degradation and poverty. This is particularly true for resource-dependent communities in the developing world such as coral reef fishing communities who will have to adapt to those new environmental conditions and novel ecosystems. It is therefore crucial to identify: i) multiscale characteristics that can influence social adaptive capacity of local communities to climate change, and ii) current and future social-ecological conditions related to climate change that might lead communities to experience unsustainable and undesirable states (i.e., "socialecological traps"). Here, we investigated social adaptive capacity and the relationship to ecological conditions in 29 small-scale fishing communities in Madagascar and Kenya in the Western Indian Ocean. We found that isolation from a market and climate stress had a significant negative relationship with social adaptive capacity, while a higher level of education and the presence of market traders (middlemen) had a positive relationship. In general, resource management through marine protected areas and locally managed marine areas had a positive influence on ecological conditions. Combining social adaptive capacity and ecological conditions revealed that 80 % of fishers households surveyed were experiencing social-ecological states that could lead to unsustainable social-ecological conditions, while 10 % might already be experiencing social-ecological traps. Our findings reveal specific mechanisms by which conservation and development activities can increase social adaptive capacity in coastal communities, including but not limited to: increasing market access and education, and mitigating future climate exposure and unsustainable fishing through improved marine conservation and management

Rising Climate Risk and Loss and Damage to Coastal Subsistence-oriented Livelihoods

Subsistence-oriented communities in tropical coastal areas face the greatest threat from climate change, with consequences manifesting through diminishing returns from small-scale fishing and farming ventures. The complementary climate, sustainable development, and biodiversity conservation policies target reducing climate risks, but effective policy outcomes depend on a thorough understanding of system-wide climate risk, community adaptation potential and gaps, and possible economic losses. Using four countries in the Western Indian Ocean (WIO) region as a case, we present a framework for quantifying climate risk to subsistence-oriented coastal communities. On average, economic losses of ecosystem services are predicted to increase with increasing climate risk, with annual losses of up to 23% and 32% of total economic value (~ US$ 516,828,468/year) under SSP2-4.5 and SSP5-8.5 scenarios by 2050, respectively. A comprehensive assessment of climate risks, ecosystem service value and cost of climate inaction can inform policy actions aimed at adapting, mitigating, and compensating for the loss and damage caused by climate change

Human-Mediated Loss of Phylogenetic and Functional Diversity in Coral Reef Fishes

Summary Beyond the loss of species richness [1-3], human activities may also deplete the breadth of evolutionary history (phylogenetic diversity) and the diversity of roles (functional diversity) carried out by species within communities, two overlooked components of biodiversity. Both are, however, essential to sustain ecosystem functioning and the associated provision of ecosystem services, particularly under fluctuating environmental conditions [1-7]. We quantified the effect of human activities on the taxonomic, phylogenetic, and functional diversity of fish communities in coral reefs, while teasing apart the influence of biogeography and habitat along a gradient of human pressure across the Pacific Ocean. We detected nonlinear relationships with significant breaking points in the impact of human population density on phylogenetic and functional diversity of parrotfishes, at 25 and 15 inhabitants/km2, respectively, while parrotfish species richness decreased linearly along the same population gradient. Over the whole range, species richness decreased by 11.7%, while phylogenetic and functional diversity dropped by 35.8% and 46.6%, respectively. Our results call for caution when using species richness as a benchmark for measuring the status of ecosystems since it appears to be less responsive to variation in human population densities than its phylogenetic and functional counterparts, potentially imperiling the functioning of coral reef ecosystems

Chagos_DATA_Proc

Vulnerability and Abondance of fish functional entities for Chagos dat

Dynamics and fate of blue carbon in a mangrove-seagrass seascape: influence of landscape configuration and land-use change

Context Seagrass meadows act as efficient natural carbon sinks by sequestering atmospheric CO2 and through trapping of allochthonous organic material, thereby preserving organic carbon (C-org) in their sediments. Less understood is the influence of landscape configuration and transformation (land-use change) on carbon sequestration dynamics in coastal seascapes across the land-sea interface. Objectives We explored the influence of landscape configuration and degradation of adjacent mangroves on the dynamics and fate of C-org in seagrass habitats. Methods Through predictive modelling, we assessed sedimentary C-org content, stocks and source composition in multiple seascapes (km-wide buffer zones) dominated by different seagrass communities in northwest Madagascar. The study area encompassed seagrass meadows adjacent to intact and deforested mangroves. Results The sedimentary C-org content was influenced by a combination of landscape metrics and inherent habitat plant- and sediment-properties. We found a strong land-to-sea gradient, likely driven by hydrodynamic forces, generating distinct patterns in sedimentary C-org levels in seagrass seascapes. There was higher C-org content and a mangrove signal in seagrass surface sediments closer to the deforested mangrove area, possibly due to an escalated export of C-org from deforested mangrove soils. Seascapes comprising large continuous seagrass meadows had higher sedimentary C-org levels in comparison to more diverse and patchy seascapes. Conclusion Our results emphasize the benefit to consider the influence of seascape configuration and connectivity to accurately assess C-org content in coastal habitats. Understanding spatial patterns of variability and what is driving the observed patterns is useful for identifying carbon sink hotspots and develop management prioritizations

Data from: Unexpected high vulnerability of functions in wilderness areas: evidence from coral reef fishes

High species richness is thought to support the delivery of multiple ecosystem functions and services under changing environments. Yet, some species might perform unique functional roles while others are redundant. Thus, the benefits of high species richness in maintaining ecosystem functioning are uncertain if functions have little redundancy, potentially leading to high vulnerability of functions. We studied the natural propensity of assemblages to be functionally buffered against loss prior to fishing activities, using functional trait combinations, in coral reef fish assemblages across unfished wilderness areas of the Indo-Pacific: Chagos Archipelago, New Caledonia and French Polynesia. Fish functional diversity in these wilderness areas is highly vulnerable to fishing, explained by species- and abundance-based redundancy packed into a small combination of traits, leaving most other trait combinations (60%) sensitive to fishing, with no redundancy. Functional vulnerability peaks for mobile and sedentary top predators, and large species in general. Functional vulnerability decreases for certain functional entities in New Caledonia, where overall functional redundancy was higher. Uncovering these baseline patterns of functional vulnerability can offer early warning signals of the damaging effects from fishing, and may serve as baselines to guide precautionary and even proactive conservation actions

French_Pol_DATA_Proc

Vulnerability and Abondance of fish functional entities for French Polynesia dat

New_Cal_DATA_Proc

Vulnerability and Abondance of fish functional entities for New Caledonia dat

Implementing a social-ecological systems framework for conservation monitoring: lessons from a multi-country coral reef program

Multi-scale social-ecological systems (SES) approaches to conservation and commons management are needed to address the complex challenges of the Anthropocene. Although SES approaches to monitoring and evaluation are advocated in global science and policy arenas, real-world applications remain scarce. Here, we describe the first operationalization and implementation of Ostrom's influential SES framework for monitoring practice across multiple countries. Designed to inform management aimed at sustaining coral reefs and the people that depend on them, we developed our SES monitoring framework through a transdisciplinary process involving academics and practitioners with expertise in social and ecological sciences. We describe the SES monitroing framework, including how it operationalizes key insights from the SES and program evaluation literatures, and demonstrate how insights from its implementation in more than 85 communities in four countries (Fiji, Indonesia, Kenya and Madagascar) are informing decision-making at multiple levels. Responding to repeated calls for guidance on applying SES approaches to monitoring and management practice, we outline the key steps of the transdisciplinary development of the framework and lessons learnt. Therefore, our work contributes to bridging the gap between SES science and commons management practice through not only providing an SES monitoring framework that can be readily applied to coral reefs and other commons, but also through demonstrating how to operationalize SES approaches for real-world monitoring and management practice