Indicators of scientific value: An under-recognised ecosystem service of coastal and marine habitats

Coastal ecosystems provide a broad range of ecosystem services, which can be used to justify habitat conservation. The cultural ecosystem services of coastal ecosystems are generally underappreciated, and this is particularly the case when quantifying their scientific value. We created a tiered set of indicators to quantify scientific value spatially, and tested them using the case study of the island nation of Singapore. We conducted a systematic review of research papers, book chapters, conference reports and academic theses produced across 10 coastal ecosystems in Singapore, including mangroves, seagrasses, coral reefs, beaches and artificial coastal structures. At least 656 articles have been produced on Singapore’s coastal zone, with 2201 unique observations, showing that scientific value is spatially variable along Singapore’s coastline. Novel indicators such as the Site Impact Factor are able to differentiate scientific value between sites. This method has shed light on an under-recognised, but important cultural ecosystem service, and is applicable to other spatially-bounded coastal, marine and terrestrial landscapes

Chapter 3 Ecosystem Services and Disservices of Mangrove Forests and Salt Marshes

Coastal wetlands such as mangrove forests and saltmarshes provide a range of important benefits to people, broadly defined as ecosystem services. These include provisioning services such as fuelwood and food, regulating services such as carbon sequestration and wave attenuation, and various tangible and intangible cultural services. However, strong negative perceptions of coastal wetlands also exist, often driven by the perceived or actual ecosystem disservices that they also produce. These can include odour, a sense of danger, and their real or perceived role in vector and disease transmission (e.g., malaria). This review provides an introduction to the ecosystem services and disservices concepts, and highlights the broad range of services and disservices provided by mangrove forests and saltmarshes. Importantly, we discuss the key implications of ecosystem services and disservices for the management of these important coastal ecosystems. Ultimately, a clear binary does not exist between ecosystem services and disservices; an ecosystem service to one stakeholder can be viewed as a disservice to another, or a service can change seasonally into a disservice, and vice versa. It is not enough to only consider the beneficial ecosystem services that coastal wetlands provide: instead, we need to provide a balanced view of coastal wetlands that incorporates the complexities that exist in how humans relate to and interact with these important coastal ecosystems

Geomorphic Gradients in Shallow Seagrass Carbon Stocks

Seagrass meadows are important sinks of organic carbon (Corg), in particular the near-surface Corg pool (≤ 15 cm) compared to deeper sediments. Near-surface carbon is highly susceptible to disturbance and loss to the atmosphere, however, inadequate accounting for variability in this pool of carbon limits their uptake into carbon accounting frameworks. We therefore investigated the spatial variability in seagrass near-surface Corg and biomass Corg across different geomorphic (estuary, lagoonal and reef-associated) and community typologies (pioneer and persistent). Near-surface Corg stock in vegetated areas (25.78 Mg Corg ha−1 ± 26.64) was twice that from unvegetated areas (14.27 Mg Corg ha−1 ± 15.86), reinforcing the paradigm that the presence of seagrass enhances carbon stocks. Lagoonal and reef-associated meadows showed similar Corg stocks (p \u3e 0.05), which were substantially higher (p \u3c 0.05) than estuary meadows. Likewise, persistent seagrass communities (Cymodocea dominance) stored higher (p \u3c 0.05) stocks of Corg than pioneer communities (Halophila and Halodule dominance). Linear regression models showed significant but weak relationships between seagrass cover, shoot density and standing biomass with near-surface Corg stocks, whereas significant and strong relationships were observed for organic matter, dry bulk density and median grain size. The results highlight the need for higher resolution carbon assessments to better understand local and regional variability, in order to better inform carbon accounting and conservation policy

Chapter 3 Ecosystem Services and Disservices of Mangrove Forests and Salt Marshes

Coastal wetlands such as mangrove forests and saltmarshes provide a range of important benefits to people, broadly defined as ecosystem services. These include provisioning services such as fuelwood and food, regulating services such as carbon sequestration and wave attenuation, and various tangible and intangible cultural services. However, strong negative perceptions of coastal wetlands also exist, often driven by the perceived or actual ecosystem disservices that they also produce. These can include odour, a sense of danger, and their real or perceived role in vector and disease transmission (e.g., malaria). This review provides an introduction to the ecosystem services and disservices concepts, and highlights the broad range of services and disservices provided by mangrove forests and saltmarshes. Importantly, we discuss the key implications of ecosystem services and disservices for the management of these important coastal ecosystems. Ultimately, a clear binary does not exist between ecosystem services and disservices; an ecosystem service to one stakeholder can be viewed as a disservice to another, or a service can change seasonally into a disservice, and vice versa. It is not enough to only consider the beneficial ecosystem services that coastal wetlands provide: instead, we need to provide a balanced view of coastal wetlands that incorporates the complexities that exist in how humans relate to and interact with these important coastal ecosystems

An Integrative Salt Marsh Conceptual Framework for Global Comparisons

Salt marshes occur globally across climatic and coastal settings, providing key linkages between terrestrial and marine ecosystems. However, salt marsh science lacks a unifying conceptual framework; consequently, historically well-studied locations have been used as normative benchmarks. To allow for more effective comparisons across the diversity of salt marshes, we developed an integrative salt marsh conceptual framework. We review ecosystem-relevant drivers from global to local spatial scales, integrate these multi-scale settings into a framework, and provide guidance on applying the framework using specific variables on 11 global examples. Overall, this framework allows for appropriate comparison of study sites by accounting for global, coastal, inter-, and intra-system spatial settings unique to each salt marsh. We anticipate that incorporating this framework into salt marsh science will provide a mechanism to critically evaluate research questions and a foundation for effective quantitative studies that deepen our understanding of salt marsh function across spatial scales

Nutrient Cycling in Tropical and Temperate Coastal Waters: Is Latitude Making a Difference?

Tropical coastal waters are highly dynamic and amongst the most biogeochemically active zones in the ocean. This review compares nitrogen (N) and phosphorus (P) cycles in temperate and tropical coastal waters. We review the literature to identify major similarities and differences between these two regions, specifically with regards to the impact of environmental factors (temperature, sunlight), riverine inputs, groundwater, lateral fluxes, atmospheric deposition, nitrogen fixation, organic nutrient cycling, primary production, respiration, sedimentary burial, denitrification and anammox. Overall, there are some similarities but also key differences in nutrient cycling, with differences relating mainly to temperature, sunlight, and precipitation amounts and patterns. We conclude that due to the differences in biogeochemical processes, we cannot directly apply cause and effect relationships and models from temperate systems in tropical coastal waters. Our review also highlights the considerable gaps in knowledge of the biogeochemical processes of tropical coastal waters compared with temperate systems. Given the ecological and societal importance of tropical coastal waters, we hope that highlighting the differences and similarities to temperate systems as well as the existing gaps, will inspire further studies on their biogeochemical processes. Such knowledge will be essential to better understand and forecast impacts on tropical coastal nutrient cycling at local, regional, and global scales

Ecosystem Services and Disservices of Mangrove Forests and Salt Marshes

Coastal wetlands such as mangrove forests and salt marshes provide a range of important benefits to people, broadly defined as ecosystem services. These include provisioning services such as fuelwood and food, regulating services such as carbon sequestration and wave attenuation, and various tangible and intangible cultural services. However, strong negative perceptions of coastal wetlands also exist, often driven by the perceived or actual ecosystem disservices that they also produce. These can include odour, a sense of danger, and their real or perceived role in vector and disease transmission (e.g. malaria). This review provides an introduction to the ecosystem services and disservices concepts and highlights the broad range of services and disservices provided by mangrove forests and salt marshes. Importantly, we discuss the key implications of ecosystem services and disservices for the management of these coastal ecosystems. Ultimately, a clear binary does not exist between ecosystem services and disservices; an ecosystem service to one stakeholder can be viewed as a disservice to another, or a service can change seasonally into a disservice, and vice versa. It is not enough to only consider the beneficial ecosystem services that coastal wetlands provide: instead, we need to provide a balanced view of coastal wetlands that incorporates the complexities that exist in how humans relate to and interact with them

An integrative salt marsh conceptual framework for global comparisons

Salt marshes occur globally across climatic and coastal settings, providing key linkages between terrestrial and marine ecosystems. However, salt marsh science lacks a unifying conceptual framework; consequently, historically well-studied locations have been used as normative benchmarks. To allow for more effective comparisons across the diversity of salt marshes, we developed an integrative salt marsh conceptual framework. We review ecosystem-relevant drivers from global to local spatial scales, integrate these multi-scale settings into a framework, and provide guidance on applying the framework using specific variables on 11 global examples. Overall, this framework allows for appropriate comparison of study sites by accounting for global, coastal, inter-, and intra-system spatial settings unique to each salt marsh. We anticipate that incorporating this framework into salt marsh science will provide a mechanism to critically evaluate research questions and a foundation for effective quantitative studies that deepen our understanding of salt marsh function across spatial scales

Rapidly Changing Range Limits in a Warming World: Critical Data Limitations and Knowledge Gaps for Advancing Understanding of Mangrove Range Dynamics in the Southeastern USA

Climate change is altering species’ range limits and transforming ecosystems. For example, warming temperatures are leading to the range expansion of tropical, cold-sensitive species at the expense of their cold-tolerant counterparts. In some temperate and subtropical coastal wetlands, warming winters are enabling mangrove forest encroachment into salt marsh, which is a major regime shift that has significant ecological and societal ramifications. Here, we synthesized existing data and expert knowledge to assess the distribution of mangroves near rapidly changing range limits in the southeastern USA. We used expert elicitation to identify data limitations and highlight knowledge gaps for advancing understanding of past, current, and future range dynamics. Mangroves near poleward range limits are often shorter, wider, and more shrublike compared to their tropical counterparts that grow as tall forests in freeze-free, resource-rich environments. The northern range limits of mangroves in the southeastern USA are particularly dynamic and climate sensitive due to abundance of suitable coastal wetland habitat and the exposure of mangroves to winter temperature extremes that are much colder than comparable range limits on other continents. Thus, there is need for methodological refinements and improved spatiotemporal data regarding changes in mangrove structure and abundance near northern range limits in the southeastern USA. Advancing understanding of rapidly changing range limits is critical for foundation plant species such as mangroves, as it provides a basis for anticipating and preparing for the cascading effects of climate-induced species redistribution on ecosystems and the human communities that depend on their ecosystem services

Blue Carbon Science, Management and Policy Across a Tropical Urban Landscape

The ability of vegetated coastal ecosystems to sequester high rates of “blue” carbon over millennial time scales has attracted the interest of national and international policy makers as a tool for climate change mitigation. Whereas focus on blue carbon conservation has been mostly on threatened rural seascapes, there is scope to consider blue carbon dynamics along highly fragmented and developed urban coastlines. The tropical city state of Singapore is used as a case study of urban blue carbon knowledge generation, how blue carbon changes over time with urban development, and how such knowledge can be integrated into urban planning alongside municipal and national climate change obligations. A systematic review of blue carbon studies in Singapore was used to support a qualitative review of Singapore’s blue carbon ecosystems, carbon budget, changes through time and urban planning and policy. Habitat loss across all blue carbon ecosystems is coarsely estimated to have resulted in the release of ∼12.6 million tonnes of carbon dioxide since the beginning of the 20th century. However, Singapore’s remaining blue carbon ecosystems still store an estimated 568,971 – 577,227 tonnes of carbon (equivalent to 2.1 million tonnes of carbon dioxide) nationally, with a small proportion of initial loss offset by habitat restoration. Carbon is now a key topic on the urban development and planning agenda, as well as nationally through Singapore’s contributions to the Paris Agreement. The experiences of Singapore show that coastal ecosystems and their blue carbon stocks can be successfully managed along an urban coastline, and can help inform blue carbon science and management along other rapidly urbanizing coastlines throughout the tropics