Climate change manifestation in the ocean, through warming, oxygen loss, increasing acidification, and changing particulate organic carbon flux (one metric of altered food supply), is projected to ...affect most deep‐ocean ecosystems concomitantly with increasing direct human disturbance. Climate drivers will alter deep‐sea biodiversity and associated ecosystem services, and may interact with disturbance from resource extraction activities or even climate geoengineering. We suggest that to ensure the effective management of increasing use of the deep ocean (e.g., for bottom fishing, oil and gas extraction, and deep‐seabed mining), environmental management and developing regulations must consider climate change. Strategic planning, impact assessment and monitoring, spatial management, application of the precautionary approach, and full‐cost accounting of extraction activities should embrace climate consciousness. Coupled climate and biological modeling approaches applied in the water and on the seafloor can help accomplish this goal. For example, Earth‐System Model projections of climate‐change parameters at the seafloor reveal heterogeneity in projected climate hazard and time of emergence (beyond natural variability) in regions targeted for deep‐seabed mining. Models that combine climate‐induced changes in ocean circulation with particle tracking predict altered transport of early life stages (larvae) under climate change. Habitat suitability models can help assess the consequences of altered larval dispersal, predict climate refugia, and identify vulnerable regions for multiple species under climate change. Engaging the deep observing community can support the necessary data provisioning to mainstream climate into the development of environmental management plans. To illustrate this approach, we focus on deep‐seabed mining and the International Seabed Authority, whose mandates include regulation of all mineral‐related activities in international waters and protecting the marine environment from the harmful effects of mining. However, achieving deep‐ocean sustainability under the UN Sustainable Development Goals will require integration of climate consideration across all policy sectors.
As use of the deep sea and its resources intensifies, consideration of climate change should become integral to planning and management. A suite of climate and biological modeling tools can inform holistic environmental management and decision making for the deep ocean on multiple fronts.
Marine electrical imaging reveals novel onshore-to-offshore submarine freshwater transport mechanism in volcanic islands.
Conventional hydrogeologic framework models used to compute ocean island ...sustainable yields and aquifer storage neglect the complexity of the nearshore and offshore submarine environment. However, the onshore aquifer at the island of Hawai‘i exhibits a notable volumetric discrepancy between high-elevation freshwater recharge and coastal discharge. In this study, we present a novel transport mechanism of freshwater moving from onshore to offshore through a multilayer formation of water-saturated layered basalts with interbedded low-permeability layers of ash/soil. Marine electromagnetic imaging reveals ∼35 km of laterally continuous resistive layers that extend to at least 4 km from west of Hawai‘i’s coastline, containing about 3.5 km
3
of freshened water. We propose that this newly found transport mechanism of fresh groundwater may be the governing mechanism in other volcanic islands. In such a scenario, volcanic islands worldwide can use these renewable offshore reservoirs, considered more resilient to climate change-driven droughts, as new water resources.
Since the 1970s, artificial reef (AR) deployment has been one of the common approaches to augment the local production of coastal fish in Malaysia. However, there is a lack of strategy to assess and ...evaluate the success of pre-deployed AR. Realizing the need for an effective qualitative and quantitative monitoring and evaluation of AR, this study proposes side-scan sonar coupled with scuba diving observation for the enhanced monitoring of pre-deployed Bioceramic Korean (BK) AR along the coast of Terengganu, Peninsular Malaysia. This method employs an integrated side-scan sonar with a data acquisition system for the detection of the precise location of the BK AR which were deployed at Tukun Telaga Batin off the Terengganu coastline in 2003 by the Fisheries Development Authority of Malaysia (FDAM). Following the determination of the exact location of three BK AR areas, a scuba diving team was sent to survey the physical conditions of the AR and assess the feasibility of the AR as an artificial habitat for marine life. The scan sonar images were compared with the captured photographs and videos acquired during the scuba diving session for a comprehensive value-added assessment. The collected data from the scuba diving session were also processed to measure the fish diversity, the fish biomass, and identify the fish community surrounding the AR. Based on the results, the BK AR remained in extremely good condition, physically intact, without significant breakage or damage, and with no major subsidence into the sediment after 19 years of deployment. A total of 108 BK AR modules were detected in three large groups using the mosaicked sonar images. Following cross-examination to validate the AR measurements using the AR’s shadows on the seafloor, the height of the BK AR consistently ranged from 1.7 m to 1.8 m. In addition, 34 species of fish from 14 families and 26 genera were identified, with most species classified as reef-associated (RA) fish with a biomass value of 1173.31 ± 1136.69 kg m−3, indicating the successfulness of the BK AR as fish-aggregating devices (FADs). The growth of hard corals on top of the bioceramic plate of the AR module further supported the diversified community of marine life surrounding the BK AR. In conclusion, the side-scan sonar coupled with scuba diving observation demonstrates an effective qualitative and quantitative technique for the monitoring and evaluation of pre-deployed AR. This strategy is recommended to be utilized to determine the success of pre-deployment AR.
•We use entropy-based contagion index to quantify spatial heterogeneity.•We evaluate the use of the metric as proxy for biodiversity in submarine canyons.•Differences of index is highly significant ...in canyon branches and the lower canyon.•Biological characteristics show inverse relationship with the index.•Potentially, the metric will be beneficial for marine spatial management.
Spatial variability in environmental conditions has been attributed as the main driver behind marine biodiversity in structurally complex environments. Despite this, spatial heterogeneity, reflecting terrain organisation of environmental conditions, is seldom quantified in the marine environment, especially at regional scale. In contrast, quantification of spatial patterns has been widely applied to characterise structural features of terrestrial landscapes and has been demonstrated to be of great use in landscape ecology and spatial planning. To address this discrepancy, we use landscape ecology indices (entropy-based contagion) and objective automated marine landscape mapping techniques to quantify marine landscape heterogeneity and evaluate the use of this metric as proxy for biodiversity in submarine canyons. Submarine canyons enhance marine landscape diversity at regional scales and provide unique habitats for diverse and abundant faunal assemblages. The deep and complex topography, strong currents and occurrence of specific oceanographic patterns affect the habitat heterogeneity potentially making canyons a hotspot for biological activity, with high faunal diversity.
Here, multibeam bathymetry and sidescan sonar imagery were used to generate a marine landscape map for Whittard Canyon, NE Atlantic, using objective automated classification and object-based image analysis (OBIA). The resulting marine landscape map was characterised by seven landscape types, of which five were found to be ecologically relevant using species indicator analysis (IndVal). Spatial heterogeneity within the landscape map was then quantified with the entropy-based contagion index. Differences in the entropy-based contagion index were highly significant between canyon branches and the lower canyon. The two main canyon branches were not significantly different from each other. Differences in entropy-based contagion value across seabed areas can help to determine areas suitable for the establishment of Marine Protected Area.
Submarine groundwater discharge (SGD) is an important phenomenon that governs hydrological cycles at the land‐to‐ocean transition zone. SGD manifests as cold and buoyant freshwaters influx from the ...seafloor to the water column that contains carbon, nutrients, metals, and greenhouse gases, altering coastal areas' oceanographical and biochemical properties. Here, we present electromagnetic imaging of large‐scale freshwater plumes in high‐resolution, offshore west Hawai'i. Electrical resistivity models detect multiple vertical freshwater plumes extending from the seafloor to the ocean surface. Additionally, our models image extensive spatially distributed surface freshwater. The resistivity of these plumes and surface freshwater ranges from ∼1 to 30 Ωm. Resistivity‐to‐salinity calculation indicates a plume‐scale salinity range of ∼0.3–9.9, containing up to 87% of freshwater. Our results imply that substantial volumes of freshwater occupy water column plumes in Hawai'i. This study offers a new and effective method to elucidate hydrogeologic and ocean processes affecting biogeochemical cycles in coastal waters worldwide.
Plain Language Summary
Submarine groundwater discharge (SGD) is a flow of cold and buoyant freshwater from the seafloor to the ocean surface. Because SGD contains carbon, nutrients, metals, and greenhouse gases, it changes coastal waters' oceanographical and biochemical properties. Therefore, SGD is an important phenomenon that governs hydrological cycles at the land‐to‐ocean transition zone. Due to the high spatial distribution and variability of SGD at the ocean surface, it is nontrivial to map SGD seep location and fluxes using traditional oceanographic methods. Here, we present electromagnetic imaging of large‐scale freshwater plumes in high‐resolution, offshore west Hawai'i. Our electrical resistivity models detect multiple vertical freshwater plumes (SGD point‐sources) as well as spatially distributed surface freshwater, extending to a distance of ∼3 km offshore Hawai'i. Plume‐scale salinity distribution indicates that these plumes contain up to 87% of freshwater. Thus, a substantial volume of freshwater occupies Hawaiian water column plumes. This is the first study to demonstrate the marine electromagnetic method's capability to image and delineate freshwater plumes from the seafloor to the ocean surface. We offer a new and effective method to elucidate hydrogeologic and ocean processes that affect biogeochemical cycles in coastal waters worldwide.
Key Points
Surface‐towed marine‐controlled source electromagnetic technique is capable of imaging freshwater plumes in high‐resolution
Multiple large‐scale freshwater plumes and surface freshwater bodies were detected offshore the island of Hawai'i
Substantial volumes of freshwater occupy seafloor to ocean surface plumes in west Hawai'i
The current study aimed to evaluate the petroleum generation potential of the Sakesar Formation. This study interprets and presents a depositional environment model, microfacies, and geochemical and ...petrophysical data of the Eocene Sakesar Formation in the Potwar Basin, Pakistan. Twenty well-cutting samples from two wells and six fresh outcrop samples were thoroughly studied. Results of total organic carbon and Rock-Eval pyrolysis of Sakesar Formation sediments show fair to good TOC contents ranging from 1.2-1.67 wt%. S2 values of samples showed fair to good generation potential. Sediments appear mature, having primarily mixed Type II-III kerogen with good oil/gas-generation potential. Three microfacies have been identified in the Sakesar Formation at the Tatral section: Bioclastic wacke-packstone, Lockhartia-rich mud-wackestone, and benthic foraminiferal wackestone. The microfacies of the Sakesar Limestone depict the deposition of the Sakesar Limestone from the distal middle ramp to restricted inner ramp settings. Petrophysical well logs analysis of the Sakesar Formation showed an average porosity of ~9.12%; the lithology was identified as limestone, having an average water saturation of ~22.32% and an average hydrocarbon saturation of ~77.68%. Thus indicating average to good reservoir properties with very good hydrocarbon saturation. Sakesar Formation sediments characteristics interpretation showed that it can act as both source rock and reservoir rock in the Potwar Basin. Keywords: Sakesar Formation; Potwar Basin; Depositional environment; microfacies. El presente estudio busca evaluar el potencial de generacion petrolifera de la formacion Sakesar. Con ese fin este trabajo presenta e interpreta un modelo ambiental deposicional, con informacion de microfacies, geoquimica y petrofisica. Un total de veinte muestras cortadas y pulidas de dos pozos y seis afloramientos se estudiaron cuidadosamente. Los resultados de los analisis de carbono organico total y de pirolisis (Rock eval) de los sedimentos de la formacion Sakesar muestran que los contenidos de carbono organico total son de regulares a buenos y oscilan entre 1.2 y 1.67 wt%. Los valores S2 de las muestras tienen un potencial de generacion entre regular y bueno. Los sedimentos se muestran maduros y tienen una mezcla primaria de kerogenos tipo II-III con un buen potencial de generacion de petroleo y gas. Tres microfacies se han identificado en la seccion Teatral de la formacion Sakesar: wacke-packstone bioclastica, wackestone de barro rico en lockhartia y wackestone de foraminiferos bentonicos. Las microfacies de las calizas de Sakesar muestran que sus deposiciones desde la rampa media distal hasta configuraciones de rampa interior restringidas. Los analisis petrofisicos de registro de pozo de la formacion Sakesar muestran una porosidad promedio de ~9.12%; la fitologia se identifico como caliza, con un promedio de saturacion de agua de ~22.32% y un promedio de saturacion de hidrocarburos de ~77.68%. Por ende, los resultados indican que en promedio las propiedades del reservorio son buenas con muy buena saturacion de hidrocarburos. La interpretacion de las caracteristicas de los sedimentos de la formacion Sakesar muestran que esta puede actuar como roca fuente o como roca reservorio en la cuenca Potwar. Palabras clave: Formacion Sakesar; Cuenca Potwar; ambiente deposicional; microfacies
This study proposes a fully automated and objective technique to map marine landscapes in submarine canyons. The method is suitable for broad and regional scale mapping derived from sonar data using ...multivariate statistical analysis. The method is divided into two main parts: the terrain analysis and the multivariate statistical analysis. The first part aims to optimise the sonar data and comprises three steps 1) data resampling, 2) determination of length scale, and 3) multiple scale analysis. The second part covers the actual marine landscape classification and consists of 1) principal component analysis (PCA), 2) K-means clustering, and 3) cluster determination. In addition, a confidence map is presented based on cluster membership derived from cluster distance in attribute space.
The technique was applied in the Lisbon–Setúbal and Cascais Canyons offshore Portugal. The area was classified into 6 marine landscapes that represent the geomorphological features present in submarine canyons. The main findings from the study are 1) the transferability of a tool from geomorphometric analysis – Estimation of Scale Parameter (ESP) – to detect the length scale of potential patterns in bathymetric grids; 2) multiple scale terrain analysis allows an appropriate discrimination of local and broad scale geomorphic features in marine landscape mapping; 3) the method not only delineates geomorphic seafloor features but also points out properties that might influence biodiversity in a complex terrain.
•We propose a fully automated and objective technique for marine landscape mapping in submarine canyons•We use a tool from geomorphic analysis to detect length scale of potential patterns in bathymetric grids•Multiple scale terrain analysis is able to discriminate local and broad scale features in the bathymetric grid•Marine landscapes do not only delineate geomorphic features but also show properties that might influence biodiversity•The method is suitable for broad/regional scale mapping in complex terrains
The current study aimed to evaluate the petroleum generation potential of the Sakesar Formation. This study interprets and presents a depositional environment model, microfacies, and geochemical and ...petrophysical data of the Eocene Sakesar Formation in the Potwar Basin, Pakistan. Twenty well-cutting samples from two wells and six fresh outcrop samples were thoroughly studied. Results of total organic carbon and Rock-Eval pyrolysis of Sakesar Formation sediments show fair to good TOC contents ranging from 1.2-1.67 wt%. S2 values of samples showed fair to good generation potential. Sediments appear mature, having primarily mixed Type II-III kerogen with good oil/gas-generation potential. Three microfacies have been identified in the Sakesar Formation at the Tatral section: Bioclastic wacke-packstone, Lockhartia-rich mud-wackestone, and benthic foraminiferal wackestone. The microfacies of the Sakesar Limestone depict the deposition of the Sakesar Limestone from the distal middle ramp to restricted inner ramp settings. Petrophysical well logs analysis of the Sakesar Formation showed an average porosity of ~9.12%; the lithology was identified as limestone, having an average water saturation of ~22.32% and an average hydrocarbon saturation of ~77.68%. Thus indicating average to good reservoir properties with very good hydrocarbon saturation. Sakesar Formation sediments characteristics interpretation showed that it can act as both source rock and reservoir rock in the Potwar Basin.
As the largest portion of the Earth's surface, the deep-sea contains various ecosystems and harbours among the highest biodiversity on the planet. Complex deep-sea environments such as submarine ...canyons are some of the true ecosystem hotspots harbouring extensive species diversity owing to their high terrain variability. However, their complexity and limited accessibility has left many unanswered questions concerning their spatial structure and ecology. Recently, there has been an increasing amount of interest to understand the ecosystem function of this challenging environment, which has led to the development of technology to enable accessibility for research and exploration. Along with this, evidence of anthropogenic impacts has been uncovered, and this calls for more effective management in this complex type of deep-sea environment. Although there is a growing awareness for conservation in the deep-sea, scientific knowledge to underpin these strategies is still inadequate. Often what is known to the scientific community is not properly conveyed to policy makers. Hence, implementation of marine spatial management is not always successful. This thesis provides a scientific framework to underpin ecosystem-based management. It examines the seabed spatial structure in submarine canyons by 1) developing a mapping procedure to represent the spatial structure using commonly available data types for seabed studies, 2) proposing an approach to quantify the structural variability as an indicator for biodiversity to aid decision-making in prioritising conservation areas and 3) evaluating the spatial structure information transfer across different spatial scales and data types. As a result, a novel technique that is objective, automated and statistically robust is developed to map marine landscapes, which are geomorphologically and ecologically meaningful. The marine landscape map is found to be the best representation of environmental characteristics in submarine canyons. Based on this finding, marine landscape configuration and composition is quantified as a proxy for habitat heterogeneity and potentially an indicator of biodiversity. Additionally, the method is transferred to a high-resolution dataset for marine landscape mapping at a local scale, in order to evaluate the evolution of spatial characteristics across data scales. This study reveals that a link between regional and local scale spatial structure can be identified and mapped, and that information from one scale can be transferred to the other. Additionally, regional scale marine landscape maps provide first-level structural information that is suitable and sufficient to facilitate marine spatial management for large heterogeneous areas such as submarine canyons.
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