Sustained ocean time series are critical for characterizing marine ecosystem shifts in a time of accelerating, and at times unpredictable, changes. They represent the only means to distinguish between natural and anthropogenic forcings, and are the best tools to explore causal links and implications for human communities that depend on ocean resources. Since the inception of sustained ocean observations, ocean time series have withstood many challenges, most prominently availability of uninterrupted funding and retention of trained personnel. This OceanObs’19 review article provides an overarching vision for sustained ocean time series observations for the next decade, focusing on the growing challenges of maintaining sustained ocean time series, including ship-based and autonomous coastal and open-ocean platforms, as well as remote sensing. In addition to increased diversification of funding sources to include the private sector, NGOs, and other groups, more effective engagement of stakeholders and other end-users will be critical to ensure the sustainability of ocean time series programs. Building a cohesive international time series network will require dedicated capacity to coordinate across observing programs and leverage existing infrastructure and platforms of opportunity. This review article outlines near-term observing priorities and technology needs; explores potential mechanisms to broaden ocean time series data applications and end-user communities; and describes current tools and future requirements for managing increasingly complex multi-platform data streams and developing synthesis products that support science and society. The actionable recommendations outlined herein ultimately form the basis for a robust, sustainable, fit-for-purpose time series network that will foster a predictive understanding of changing ocean systems for the benefit of society.
Acoustics play a central role in humankind’s interactions with the ocean and the life within. Passive listening to ocean “soundscapes” informs us about the physical and bio-acoustic environment from earthquakes to communication between fish. Active acoustic probing of the environment informs us about ocean topography, currents and temperature, and abundance and type of marine life vital to fisheries and biodiversity related interests. The two together in a multi-purpose network can lead to discovery and improve understanding of ocean ecosystem health and biodiversity, climate variability and change, and marine hazards and maritime safety. Passive acoustic monitoring (PAM) of sound generated and utilized by marine life as well as other natural (wind, rain, ice, seismics) and anthropogenic (shipping, surveys) sources, has dramatically increased worldwide to enhance understanding of ecological processes. Characterizing ocean soundscapes (the levels and frequency of sound over time and space, and the sources contributing to the sound field), temporal trends in ocean sound at different frequencies, distribution and abundance of marine species that vocalize, and distribution and amount of human activities that generate sound in the sea, all require passive acoustic systems. Acoustic receivers are now routinely acquiring data on a global scale, e.g., Comprehensive Nuclear-Test-Ban Treaty Organization International Monitoring System hydroacoustic arrays, various regional integrated ocean observing systems, and some profiling floats. Judiciously placed low-frequency acoustic sources transmitting to globally distributed PAM and other systems provide: (1) high temporal resolution measurements of large-scale ocean temperature/heat content variability, taking advantage of the inherent integrating nature of acoustic travel-time data using tomography; and (2) acoustic positioning (“underwater GPS”) and communication services enabling basin-scale undersea navigation and management of floats, gliders, and AUVs. This will be especially valuable in polar regions with ice cover. Routine deployment of sources during repeat global-scale hydrographic ship surveys would provide high spatial coverage snapshots of ocean temperatures. To fully exploit the PAM systems, precise timing and positioning need to be broadly implemented. Ocean sound is now a mature Global Ocean Observing System (GOOS) “essential ocean variable,” which is one crucial step toward providing a fully integrated global multi-purpose ocean acoustic observing system.
The diversity of life in the sea is critical to the health of ocean ecosystems that support living resources and therefore essential to the economic, nutritional, recreational, and health needs of billions of people. Yet there is evidence that the biodiversity of many marine habitats is being altered in response to a changing climate and human activity. Understanding this change, and forecasting where changes are likely to occur, requires monitoring of organism diversity, distribution, abundance, and health. It requires a minimum of measurements including productivity and ecosystem function, species composition, allelic diversity, and genetic expression. These observations need to be complemented with metrics of environmental change and socio-economic drivers. However, existing global ocean observing infrastructure and programs often do not explicitly consider observations of marine biodiversity and associated processes. Much effort has focused on physical, chemical and some biogeochemical measurements. Broad partnerships, shared approaches, and best practices are now being organized to implement an integrated observing system that serves information to resource managers and decision-makers, scientists and educators, from local to global scales. This integrated observing system of ocean life is now possible due to recent developments among satellite, airborne, and in situ sensors in conjunction with increases in information system capability and capacity, along with an improved understanding of marine processes represented in new physical, biogeochemical, and biological models.
Ocean surface winds, currents, and waves play a crucial role in exchanges of momentum, energy, heat, freshwater, gases, and other tracers between the ocean, atmosphere, and ice. Despite surface waves being strongly coupled to the upper ocean circulation and the overlying atmosphere, efforts to improve ocean, atmospheric, and wave observations and models have evolved somewhat independently. From an observational point of view, community efforts to bridge this gap have led to proposals for satellite Doppler oceanography mission concepts, which could provide unprecedented measurements of absolute surface velocity and directional wave spectrum at global scales. This paper reviews the present state of observations of surface winds, currents, and waves, and it outlines observational gaps that limit our current understanding of coupled processes that happen at the air-sea-ice interface. A significant challenge for the coming decade of wind, current, and wave observations will come in combining and interpreting measurements from (a) wave-buoys and high-frequency radars in coastal regions, (b) surface drifters and wave-enabled drifters in the open-ocean, marginal ice zones, and wave-current interaction “hot-spots,” and (c) simultaneous measurements of absolute surface currents, ocean surface wind vector, and directional wave spectrum from Doppler satellite sensors.
On March 1, 1954, the United States conducted its largest thermonuclear weapon test in Bikini Atoll in the Marshall Islands; the detonation was code-named “Castle Bravo.” Radioactive deposits in the ocean sediment at the bomb crater are widespread and high levels of contamination remain today. One hundred thirty cores were collected from the top 25 cm of surface sediment at ocean depths approaching 60 m over a ∼2-km2 area, allowing for a presentation of radiation maps of the Bravo crater site. Radiochemical analyses were performed on the following radionuclides: plutonium-(239,240), plutonium-238, americium-241, bismuth-207, and cesium-137. Large values of plutonium-(239,240), americium-241, and bismuth-207 are found. Comparisons are made to core sample results from other areas in the northern Marshall Islands.
Integration of observations of the coastal ocean continuum, from regional oceans to shelf seas and estuaries/deltas with models, can substantially increase the value of observations and enable a wealth of applications. In particular, models can play a critical role at connecting sparse observations, synthesizing them, and assisting the design of observational networks; in turn, whenever available, observations can guide coastal model development. Coastal observations should sample the two-way interactions between nearshore, estuarine and shelf processes and open ocean processes, while accounting for the different pace of circulation drivers, such as the fast atmospheric, hydrological and tidal processes and the slower general ocean circulation and climate scales. Because of these challenges, high-resolution models can serve as connectors and integrators of coastal continuum observations. Data assimilation approaches can provide quantitative, validated estimates of Essential Ocean Variables in the coastal continuum, adding scientific and socioeconomic value to observations through applications (e.g., sea-level rise monitoring, coastal management under a sustainable ecosystem approach, aquaculture, dredging, transport and fate of pollutants, maritime safety, hazards under natural variability or climate change). We strongly recommend an internationally coordinated approach in support of the proper integration of global and coastal continuum scales, as well as for critical tasks such as community-agreed bathymetry and coastline products.
Fisheries co-management is an increasingly globalized concept, and a cornerstone of the Voluntary Guidelines for Securing Sustainable Small-scale Fisheries in the Context of Food Security and Poverty Eradication, adopted by the United Nations Food and Agriculture Organization member states in 2014. Timor-Leste is a politically young country in the relatively rare position of having underexploited fisheries in some areas that can be leveraged to improve coastal livelihood outcomes and food and nutrition security. The collaborative and decentralized characteristics of co-management appeal to policymakers in Timor-Leste with provisions for co-management and customary laws applied to resource use were incorporated into state law in 2004 and again reinforced in 2012 revisions. The first fisheries co-management pilots have commenced where management arrangements have been codified through tara bandu, a process of setting local laws built around ritual practice that prohibits nominated activities under threat of spiritual and material sanctions. To date, however, there has been little critical evaluation of the suitability or potential effectiveness of co-management or tara bandu in the Timor-Leste fisheries context. To address this gap, we adapted the interactive governance framework to review the ecological, social and governance characteristics of Timor-Leste’s fisheries to explore whether co-management offers a valid and viable resource governance model. We present two co-management case studies and examine how they were established, who was involved, the local institutional structures, and the fisheries governance challenges they sought to address. Despite their relative proximity, the two sites contrasted in local ecology and fishery type; community institutions were starkly different but equally strong; and one site had tangible economic benefits to justify compliance, where the other had marginal and anecdotal fishery gains. In our review of the broader governance landscape in Timor-Leste, we see co-management as a useful mechanism to govern small-scale fisheries, but there is a need to connect legitimized local institutions with hierarchical governance of higher and external influences. Initial successes with implementing tara banduincorporating a small marine closure have stimulated other communities to implement no-take zones – one universally popular but very limited interpretation of co-management. However, we highlight the need for a set of guiding principles to ensure legitimate community engagement, and avoid external appropriation that may reinforce marginalization of certain user groups or customary power hierarchies.
The Maltese Islands have a very active recreational fishing community which may affect the coastal marine ecosystem. Despite this, studies to scientifically document the effects of this activity have been lacking prior to works between July 2012 and June 2017 presented here as a case study. This project, with the aim of collecting long-term data on the characteristics, trends, catches and impacts to fish populations of the recreational shore sport fishery at the national level also involved a pilot study on hobby shore angling. Two thousand five hundred and eighty nine roving-access creel surveys conducted during 132 sport fishing events and 159 catches from hobby fishers were documented with the methodology used also applicable to shore fishing taking place in the Mediterranean and elsewhere. Ninety species belonging to twenty-nine families were documented with the most common being the Sparidae and Labridae. Catch per unit effort was higher for sport fishers with hobby fishers targeting larger fish. Results from this case study go to augment the limited and necessary knowledge on this fishing sector in the Mediterranean. Findings also indicate that recreational fisheries need to be taken into account when considering conservation measures for national, regional and global fisheries management.
Coastal zones are highly dynamical systems affected by a variety of natural and anthropogenic forcing factors that include sea level rise, extreme events, local oceanic and atmospheric processes, ground subsidence, etc. However, so far, they remain poorly monitored on a global scale. To better understand changes affecting world coastal zones and to provide crucial information to decision-makers involved in adaptation to and mitigation of environmental risks, coastal observations of various types need to be collected and analyzed. In this white paper, we first discuss the main forcing agents acting on coastal regions (e.g., sea level, winds, waves and currents, river runoff, sediment supply and transport, vertical land motions, land use) and the induced coastal response (e.g., shoreline position, estuaries morphology, land topography at the land–sea interface and coastal bathymetry). We identify a number of space-based observational needs that have to be addressed in the near future to understand coastal zone evolution. Among these, improved monitoring of coastal sea level by satellite altimetry techniques is recognized as high priority. Classical altimeter data in the coastal zone are adversely affected by land contamination with degraded range and geophysical corrections. However, recent progress in coastal altimetry data processing and multi-sensor data synergy, offers new perspective to measure sea level change very close to the coast. This issue is discussed in much detail in this paper, including the development of a global coastal sea-level and sea state climate record with mission consistent coastal processing and products dedicated to coastal regimes. Finally, we present a new promising technology based on the use of Signals of Opportunity (SoOp), i.e., communication satellite transmissions that are reutilized as illumination sources in a bistatic radar configuration, for measuring coastal sea level. Since SoOp technology requires only receiver technology to be placed in orbit, small satellite platforms could be used, enabling a constellation to achieve high spatio-temporal resolutions of sea level in coastal zones.
A major challenge for managing impacts and implementing effective mitigation measures and adaptation strategies for coastal zones affected by future sea level (SL) rise is our limited capacity to predict SL change at the coast on relevant spatial and temporal scales. Predicting coastal SL requires the ability to monitor and simulate a multitude of physical processes affecting SL, from local effects of wind waves and river runoff to remote influences of the large-scale ocean circulation on the coast. Here we assess our current understanding of the causes of coastal SL variability on monthly to multi-decadal timescales, including geodetic, oceanographic and atmospheric aspects of the problem, and review available observing systems informing on coastal SL. We also review the ability of existing models and data assimilation systems to estimate coastal SL variations and of atmosphere-ocean global coupled models and related regional downscaling efforts to project future SL changes. We discuss (1) observational gaps and uncertainties, and priorities for the development of an optimal and integrated coastal SL observing system, (2) strategies for advancing model capabilities in forecasting short-term processes and projecting long-term changes affecting coastal SL, and (3) possible future developments of sea level services enabling better connection of scientists and user communities and facilitating assessment and decision making for adaptation to future coastal SL change.
The accumulation of aquatic organisms on the wetted surfaces of vessels (i.e., vessel biofouling) negatively impacts world-wide shipping through reductions in vessel performance and fuel efficiency, and increases in emissions. Vessel biofouling is also a potent mechanism for the introduction and spread of marine non-indigenous species. Guidance and regulations from the International Maritime Organization, New Zealand, and California have recently been adopted to address biosecurity risks, primarily through preventive management. However, appropriate reactive management measures may be necessary for some vessels. Vessel in-water cleaning or treatment (VICT) has been identified as an important tool to improve operating efficiency and to reduce biosecurity risks. VICT can be applied proactively [i.e., to prevent the occurrence of, or to remove, microfouling (i.e., slime) or prevent the occurrence of macrofouling organisms – large, distinct multicellular organisms visible to the human eye], or reactively (i.e., to remove macrofouling organisms). However, unmanaged VICT includes its own set of biosecurity and water quality risks. Regulatory policies and technical advice from California and New Zealand have been developed to manage these risks, but there are still knowledge gaps related to the efficacy of available technologies. Research efforts are underway to address these gaps in order to inform the regulatory and non-regulatory application of VICT.
The structures, functions, and services provided by coral reef ecosystems are deteriorating worldwide. However, not all coral reefs are affected the same way, with some showing signs of resistance and/or recovery from disturbances. Understanding the drivers and feedbacks that contribute to shifts in community structure is valuable to support resilience-based management. In this study, key community variables that influence the resilience of coral reef ecosystems were examined in 64 sites of the Mesoamerican Reef (MAR) monitored in both 2006 and 2016, as part of the Healthy Reef Initiative (HRI), using the Atlantic and Gulf Rapid Reef Assessment (AGRRA) monitoring protocol. Based on benthic cover thresholds, sites were classified into three different states: coral state (CS) with >10% live coral and <5% fleshy macroalgae; stressed coral state (SCS) with >10% live coral and >5% fleshy macroalgae and; depauperate coral state (DCS) <10% live coral. The associations between site states and the density of different fish functional groups were analyzed to determine their effects on coral reef resilience. The results highlight that territorial herbivores (algal-gardening damselfish) may play a key role in maintaining feedbacks toward macroalgae-stressed states. This supports the recommendation of reinforcing Marine Replenishment Zones (MRZ) in order to promote healthy populations of resident predator fish (like groupers and snappers), which could potentially regulate algal-gardening damselfish populations and diminish negative cascade effects on coral reefs. Collaborative and resilience-based management will continue to be promoted by the HRI partners, supporting the establishment of additional MRZs along with ongoing efforts to directly protect herbivorous fish (surgeonfish and parrotfish) and to improve water quality, through better wastewater treatment, watershed management, and coastal development plans, with the purpose of continuing to build coral reef resilience in the MAR.
We investigate the role of a warm sea-surface temperature (SST) anomaly (hot-spot of typically 3 K to 5 K) on the aggregation of convection using cloud resolving simulations in a non-rotating framework. It is well known that SST gradients can spatially organize convection. Even with uniform SST, the spontaneous self-aggregation of convection is possible above a critical SST (here 295 K), arising mainly from radiative feedbacks. We investigate how a circular hot-spot helps organize convection, and how self-aggregation feedbacks modulate this organization. The hot-spot significantly accelerates aggregation, particularly for warmer/larger hot-spots, and extends the range of SSTs for which aggregation occurs, however at cold SST (290 K) the aggregated cluster disaggregates if we remove the hot-spot. Large convective instability over the hot-spot leads to stronger convection and generates a large-scale circulation which forces the subsidence drying outside the hot-spot. Indeed, convection over the hot-spot brings the atmosphere towards a warmer temperature. The warmer temperatures are imprinted over the whole domain by gravity waves and subsidence warming. The initial transient warming and concomitant subsidence drying suppress convection outside the hot-spot, thus driving the aggregation. The hot-spot induced large-scale circulation can enforce the aggregation even without radiative feedbacks for hot-spots sufficiently large/warm. The strength of the large-scale circulation, which defines the speed of aggregation, is a function of the hot-spot fractional area. At equilibrium, once the aggregation is well established, the moist convective region with upward mid-tropospheric motion, centered over the hot-spot, has an area surprisingly independent of the hot-spot size.
This research examines the form, social function, and policy implications of customary marine tenure (CMT) in Ngarchelong, a rural and fishery-dependent state in the Republic of Palau. Using ethnography, we find that CMT in Ngarchelong persists in a state of legal pluralism, expanding the normative space for asserting and contesting fishing privileges. Flexible administration of CMT provides benefits to the resident community, including material support from nonresidents and the strengthening of social bonds and networks. A fishery permit system under consideration would redefine fishery access as a privilege granted by government, thereby potentially impacting the social benefits supported by the community’s administration of CMT. With applications beyond Palau, we discuss an alternative management approach that could better harmonize fishery policy with local social context, thereby preserving the social functions of contemporary CMT.
Environmental DNA (eDNA) analyses have enabled more efficient surveillance of species distribution and composition than conventional methods. However, the characteristics and dynamics of eDNA (e.g., origin, state, transport, and fate) remain unknown. This is especially limited for the eDNA derived from nuclei (nu-eDNA), which has recently been used in eDNA analyses. Here, we compared the particle size distribution (PSD) of nu-eDNA from Japanese Jack Mackerel (Trachurus japonicus) with that of mt-eDNA (eDNA derived from mitochondria) reported in previous studies. We repeatedly sampled rearing water from the tanks with multiple temperature and fish biomass levels, and quantified the copy numbers of size-fractioned nu-eDNA. We found that the concentration of nu-eDNA was higher than that of mt-eDNA at 3-10 µm size fraction. Moreover, at the 0.8-3 µm and 0.4-0.8 µm size fractions, eDNA concentrations of both types increased with higher temperature and their degradation tended to be suppressed. These results imply that the production of eDNA from large to small size fractions could buffer the degradation of small-sized eDNA, which could improve its persistence in water. Our findings will contribute to refine the difference between nu- and mt-eDNA properties, and assist eDNA analyses as an efficient tool for the conservation of aquatic species.
Tourism plays a vital role in the United Nations Sustainable Development Goals. Achieving sustainable tourism is a continuous process, requiring the informed participation of all relevant stakeholders, as well as strong political leadership to ensure broad participation and consensus building (Making Tourism More Sustainable - A Guide for Policy Makers, United Nations Environment Programme and United Nations World Tourism Organization, 2005, p.11–12).
Marine Protected Areas (MPAs) are special areas of the marine environment specifically established and managed, through legal or other effective mechanisms, to “achieve the long-term conservation of nature with associated ecosystem services and cultural values” (Day et al., International Union for Conservation of Nature, 2012). Tourism development has been considered a key accompanying strategy in creating alternative livelihood options for communities living adjacent to MPAs, particularly in Nha Trang Bay (NTB), where the first MPA was...
Artificial light at night (ALAN) is a recently acknowledged form of anthropogenic pollution of growing concern to the biology and ecology of exposed organisms. Though ALAN can have detrimental effects on physiology and behaviour, we have little understanding of how marine organisms in coastal areas may be impacted. Here, we investigated the effects of ALAN exposure on coral reef fish larvae during the critical recruitment stage, encompassing settlement, metamorphosis, and post-settlement survival. We found that larvae avoided illuminated settlement habitats, however those living under ALAN conditions for 10 days post-settlement experienced changes in swimming behaviour and higher susceptibility to nocturnal predation. Although ALAN-exposed fish grew faster and heavier than control fish, they also experienced significantly higher mortality rates by the end of the experimental period. This is the first study on the ecological impacts of ALAN during the early life history of marine fish.
On the basis of an analysis of recent reviews and other published sources, as well as the author’s unpublished data, an annotated checklist of fishes and fish-like animals found in the Russian waters of the northwestern Pacific Ocean at depths greater than 1000 m was compiled. The results show that 244 species of fishes and fish-like animals are currently recorded in this region representing 145 genera, 68 families and 24 orders. The most diverse by species are three families: Zoarcidae, Liparidae, and Myctophidae, which account for about 33% of all recorded species. The maximum number of species (230) was observed within the bathymetric range of 1000-2000 m, which is likely due to diurnal and seasonal vertical migrations of these species, for which the main habitat is the mesopelagial, upper continental slope and the adjacent lower shelf waters.
Reconstructing past sea levels can help constrain uncertainties surrounding the rate of change, magnitude, and impacts of the projected increase through the 21st century. Of significance is the mid-Holocene relative sea-level highstand in tectonically stable and remote (far-field)locations from major ice sheets. The east coast of Australia provides an excellent arena in which to investigate changes in relative sea level during the Holocene. Considerable debate surrounds both the peak level and timing of the east coast highstand. The southeast Australian site of Bulli Beach provides the earliest evidence for the establishment of a highstand in the Southern Hemisphere, although questions have been raised about the pretreatment and type of material that was radiocarbon dated for the development of the regional sea-level curve. Here we undertake a detailed morpho- and chronostratigraphic study at Bulli Beach to better constrain the timing of the Holocene highstand in eastern Australia. In contrast to wood and charcoal samples that may provide anomalously old ages, probably due to inbuilt age, we find that short-lived terrestrial plant macrofossils provide a robust chronological framework. Bayesian modelling of the ages provide improved dating of the earliest evidence for a highstand at 6,880±50 cal BP, approximately a millennium later than previously reported. Our results from Bulli now closely align with other sea-level reconstructions along the east coast of Australia, and provide evidence for a synchronous relative sea-level highstand that extends from the Gulf of Carpentaria to Tasmania. Our refined age appears to be coincident with major ice mass loss from Northern Hemisphere and Antarctic ice sheets, supporting previous studies that suggest these may have played a role in the relative sea-level highstand. Further work is now needed to investigate the environmental impacts of regional sea levels, and refine the timing of the subsequent sea-level fall in the Holocene and its influence on coastal evolution.
The management and conservation of marine resources in Seychelles, a small island developing state (SIDS) in the western Indian Ocean, is fundamental to maintaining the flow of international visitors which forms the mainstay of the nation's economy. There is an increasing trend towards empowering non-governmental organisations and parastatal entities with protected area management responsibilities, which partly reflects the chronic underfunding of the state protected area management institution. This paper explores these and related issues through a governance analysis of Curieuse Marine National Park, which is the most popular state-owned marine national park in terms of recorded visitor numbers. This demonstrates that the inability to implement economic incentives through not fully capitalising on the use and non-use values of the park has deleterious consequences for managing the combined impacts of tourism and fisheries on the ecological assets of the park. Furthermore, the capacity of the state management institution is being eroded through a focus on the development of an extensive network of new marine protected areas under the direction of an international non-governmental organisation. Suggestions are made that could strengthen economic, participative and interpretative incentives to provide a more sustainable basis for marine national park management.