A carbon sink is anything, natural or otherwise, that accumulates and stores some carbon-containing chemical compound for an indefinite period and thereby removes carbon dioxide from the atmosphere. Globally, the two most important carbon sinks are vegetation and the ocean. Soil is an important carbon storage medium. Much of the organic carbon retained in the soil of agricultural areas has been depleted due to intensive farming. "Blue carbon" designates carbon that is fixed via the ocean ecosystems. Mangroves, salt marshes and seagrasses make up a majority of ocean plant life and store large quantities of carbon.
A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in several plant families. They occur worldwide in the tropics and subtropics and even some temperate coastal areas, mainly between latitudes 30° N and 30° S, with the greatest mangrove area within 5° of the equator. Mangrove plant families first appeared during the Late Cretaceous to Paleocene epochs, and became widely distributed in part due to the movement of tectonic plates. The oldest known fossils of mangrove palm date to 75 million years ago.
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone. Estuaries are subject both to marine influences such as tides, waves, and the influx of saline water, and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.
Wetlands, or simply a wetland, is a distinct ecosystem that is flooded or saturated by water, either permanently or seasonally. Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The primary factor that distinguishes wetlands from terrestrial land forms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique anoxic hydric soils. Wetlands are considered among the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal species. Methods for assessing wetland functions, wetland ecological health, and general wetland condition have been developed for many regions of the world. These methods have contributed to wetland conservation partly by raising public awareness of the functions some wetlands provide.
Peat swamp forests are tropical moist forests where waterlogged soil prevents dead leaves and wood from fully decomposing. Over time, this creates a thick layer of acidic peat. Large areas of these forests are being logged at high rates.
Mangrove forests, also called mangrove swamps, mangrove thickets or mangals, are productive wetlands that occur in coastal intertidal zones. Mangrove forests grow mainly at tropical and subtropical latitudes because mangroves cannot withstand freezing temperatures. There are about 80 different species of mangroves, all of which grow in areas with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate.
A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and long green, grass-like leaves. They produce seeds and pollen and have roots and rhizomes which anchor them in seafloor sand.
Marine ecosystems are the largest of Earth's aquatic ecosystems and exist in waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply and 90% of habitable space on Earth. Seawater has an average salinity of 35 parts per thousand of water. Actual salinity varies among different marine ecosystems. Marine ecosystems can be divided into many zones depending upon water depth and shoreline features. The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, and tuna live. The benthic zone consists of substrates below water where many invertebrates live. The intertidal zone is the area between high and low tides. Other near-shore (neritic) zones can include mudflats, seagrass meadows, mangroves, rocky intertidal systems, salt marshes, coral reefs, lagoons. In the deep water, hydrothermal vents may occur where chemosynthetic sulfur bacteria form the base of the food web.
Mangrove ecosystems represent natural capital capable of producing a wide range of goods and services for coastal environments and communities and society as a whole. Some of these outputs, such as timber, are freely exchanged in formal markets. Value is determined in these markets through exchange and quantified in terms of price. Mangroves are important for aquatic life and home for many species of fish.
Mangrove restoration is the regeneration of mangrove forest ecosystems in areas where they have previously existed. The practice of mangrove restoration is grounded in the discipline of restoration ecology, which aims to “[assist] the recovery of resilience and adaptive capacity of ecosystems that have been degraded, damaged, or destroyed”. Since environmental impacts are an ongoing threat, to successfully restore an ecosystem implies not merely to recreate its former condition, but to strengthen its capacity to adapt to change over time. Mangrove forests are most likely to thrive in the upper half of the intertidal zone. If planted below the mean tide level, or subject to too great a sea level rise, they may fail to thrive. Success will also depend on the species chosen and their suitability to conditions.
Blue carbon is a term used in the climate change mitigation context that refers to "biologically driven carbon fluxes and storage in marine systems that are amenable to management." Most commonly, it refers to the role that tidal marshes, mangroves and seagrasses can play in carbon sequestration. Such ecosystems can contribute to climate change mitigation and also to ecosystem-based adaptation. However, when coastal blue carbon ecosystems are degraded or lost they release carbon back to the atmosphere.
Professor Jessica Meeuwig is the inaugural director of the Centre for Marine Futures at the University of Western Australia (UWA). In 2012 she was appointed as a Conservation Fellow of the Zoological Society of London and was also named as one of the 100 most influential people in Western Australia by The West Australian newspaper.
Sharon Anita Robinson is an Antarctic researcher known for her work on climate change and bryophytes. She is the Executive Director of the UOW Global Challenges Program and Leader of the Program's Sustaining Coastal and Marine Zones Challenge at the University of Wollongong. She is Deputy-Director Science Implementation and UOW Node Lead of the Securing Antarctica’s Environmental Future program, a Special Research Initiative on Excellence in Antarctic Science from the Australian Research Council, worth $36 million over the next seven years (2020-2026). Robinson is a science facilitator for the Homeward Bound project, a leadership program for women in STEMM. She was a faculty member for HB3 (2018-2019) and HB5 (2020-2021) expeditions.
Carlos Manuel Duarte is a marine ecologist conducting research on marine ecosystems globally, from polar to the tropical ocean and from near-shore to deep-sea ecosystems. His research addresses biodiversity in the oceans, the impacts of human activity on marine ecosystems, and the capacity of marine ecosystems to recover from these impacts. He is also interested in transdisciplinary research, collaborating with scientists and engineers across a broad range of fields to solve problems in the marine ecosystem and society. He is currently a Distinguished Professor at the King Abdullah University of Science and Technology and executive director of the Coral Research and Development Accelerator Platform.
Human activities affect marine life and marine habitats through overfishing, habitat loss, the introduction of invasive species, ocean pollution, ocean acidification and ocean warming. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.
A marine coastal ecosystem is a marine ecosystem which occurs where the land meets the ocean. Marine coastal ecosystems include many different types of marine habitats, such as estuaries and lagoons, salt marshes and mangrove forests, seagrass meadows and coral reefs, kelp forests and backwaters. Directly and indirectly these provide a vast range of ecosystem services for humans, such as sequestering carbon, cycling nutrients and elements, providing nurseries and fishing grounds for commercial fisheries, preventing coastal erosion and moderating extreme events, as well as providing recreational services and supporting tourism.
Barbara Louise Chilvers is a New Zealand marine biologist who researches marine mammals. She is Professor of Wildlife Ecology in the School of Veterinary Science at Massey University and Director of Wildbase Oiled Wildlife Response at the university.
Jennifer Lee Stauber is an Australian ecotoxicologist and chief research scientist at the CSIRO Land and Water.
Mariah Suzanne Carbone is an American geophysicist who is a professor of Geosciences at the Center for ecosystem science and society, Northern Arizona University. She studies terrestrial ecosystems and how they respond to environmental change.
Stacy Philpott is an American ecologist who is a professor at the University of California, Santa Cruz. Her research considers agroecology and the conservation of biodiversity. She was elected a Fellow of the Ecological Society of America in 2021.
