Seafloor Habitat Research Articles

Sediment microtopography predicts localised benthic ecosystem functioning and the effect of species interactions

Soft-sediment ecosystems play a crucial role in marine environments, yet understanding the relationships between species composition and ecosystem functioning remains challenging. We investigated the potential of sediment microtopography as a predictor of ecosystem functioning in soft-sediment environments. We conducted controlled laboratory experiments focusing on the activity and microtopography generated by 2 co-occurring and functionally important species: the tellinid bivalve Macomona liliana and the maldanid polychaete Macroclymenella stewartensis. Custom-built, flow-through, gas-tight tanks were utilized to quantify sediment microtopography and assess benthic fluxes and porewater nutrient concentrations. Rugosity explained between 35 and 61% of the variability in oxygen, ammonium and nitrate + nitrite fluxes and was positively correlated with the variability of deep porewater ammonium concentrations. As a first step to validating direct links between microtopography and biophysical drivers of ecosystem processes, we highlight the potential to advance biodiversity-ecosystem function relationships for seafloor habitats. Broader investigation of the potential of microtopography as a surrogate for ecosystem functioning will lay the groundwork for novel approaches to predict and characterize changes in these vital coastal environments and inform management strategies.

Habitat selection and influence on hunting success in female Australian fur seals

Determining the factors influencing habitat selection and hunting success in top predators is crucial for understanding how these species may respond to environmental changes. For marine top predators, such factors have been documented in pelagic foragers, with habitat use and hunting success being linked to chlorophyll-a concentrations, sea surface temperature and light conditions. In contrast, little is known about the determinants of benthic marine predators. The Australian fur seal (Arctocephalus pusillus doriferus) is a benthic-diving forager that has a breeding and foraging distribution largely restricted to Bass Strait, the shallow (max. depth 80 m) continental shelf region between the Australian mainland and Tasmania. The species forages mostly on benthic prey and represents the greatest resident marine predator biomass in south-eastern Australia. The region is also one of the world’s fastest-warming marine areas and oceanographic changes are influencing shifts in prey distribution and abundance. In the present study, GPS-derived locations of benthic dives (n = 288,449) and dive behaviour metrics were used to determine seafloor habitat selection and factors influencing hunting success in 113 lactating adult females from Kanowna Island during the winters of 2006–2021. Individuals non-randomly selected foraging habitats comprised of deeper, steeper sloped, muddy-sandy areas with less gravel and highly disturbed regions (P < 0.01). Hunting success was greatest in shallower rocky reefs (< 30 m) and deep areas (> 40 m) characterised by moderate presence of gravel (25–50%) and substantial rock composition (50–75%) on the seabed. These findings suggest that habitat use and hunting success in adult female Australian fur seals could be impacted by predicted oceanographic changes, such as rising temperature, altered currents and waves which may modify seafloor characteristics and benthic communities.

Establishment and characterization of novel spontaneously immortalized larval cell lines from sablefish Anoplopoma fimbria.

Sablefish Anoplopoma fimbria is a groundfish of the North PacificOceantypically found in sea floor habitat at depths to 2700m. Prized as a food fish with exceptionally high market value, sablefish aquaculture has been sought to provide a sustainable source of this fish to meet market demands. While commercial culture has successfully produced market-sized fish in Pacific coastal environments, production has been hampered by disease and the overall lack of information on sablefish health and immunology. To begin to address these knowledge gaps, herein we describe the isolation and characterization of spontaneously immortalized sablefish larval cell lines (AFL). Six sublines were established from pools of early yolk-sac larvae, while attempts to develop tissue-specific-derived cell lines were unsuccessful. The six yolk-sac larval cell lines each display two morphologies in culture, an elongated fibroblast-like cell type, and a rounded squamous or epithelial-like cell type. Cytogenetic characterization suggests that both cell types are diploid (2n = 48) with 24 pairs of chromosomes, 23 pairs of autosomes, and 1 pair of sex chromosomes. A small proportion (11%) of AFL cells display tetraploidy. Incubation temperature and medium composition experiments revealed HEPES buffered L-15 media containing 10-20% FBS at temperatures between 15 and 18° C yielded optimal cell growth. These growth characteristics suggest that sablefish larval cells display a robustness for varying growth conditions. The establishment of AFL cell lines provides a foundational tool to study the physiology, health, immunology, and cell and molecular biology of sablefish.

High-frequency study of megafaunal communities on whale bone, wood and carbonate in hypoxic Barkley Canyon

Organic-rich whale bones and wood falls occur widely in the deep sea and support diverse faunal communities, contributing to seafloor habitat diversity. Changes in community structure through succession on deep-sea bone/wood substrates are modulated by ecosystem engineers, i.e., bone-eating Osedax annelids, and wood-boring Xylophaga bivalves. Here, we use a comparative experimental approach and Ocean Networks Canada’s (ONC) cabled observatory in hypoxic Barkley Canyon to study, at high temporal resolution, colonization and succession on whale-bone, Douglas fir wood, and control carbonate rock over 8.3 mo. Experimental substrates were similar in size and mounted on PVC plates near the seafloor at 890 m depth and monitored by high-definition video camera for 5-min intervals every 6-12 h over a period of 8.3 mo. A broad range of seafloor and sea-surface environmental variables were also monitored at this site over the 8.3 mo to account for environmental variability and food input. Following loss of the high-definition camera, substrates were surveyed approximately annually with lower resolution ROV video for an additional 8.5 y. We find that megafaunal abundances, species diversity, and community structure varied substantially over 8.3 mo on each substrate, with markedly different patterns on whale bones due to the development of extensive white bacterial mats. A combination of seafloor and sea surface variables explained &amp;lt; 35% of bone/wood community variation. Bone-eating Osedax annelids failed to colonize whale bones even after 9.2 years, and boring Xylophaga bivalves colonized the wood at much lower rates than in better oxygenated deep-sea locations. Species diversity on whale-bone and wood substrates appeared to be substantially reduced due to the absence of ecosystem engineers and the low oxygen concentrations. We hypothesize that Osedax/Xylophaga colonization, bone/wood degradation, and bone/wood community development may be limited by oxygen concentrations of 0.22 - 0.33 ml.l on the NE Pacific margin, and that OMZ expansion due to climate change will reduce whale-bone and wood degradation, and the contribution of whale falls and wood falls to beta diversity, on the NE Pacific margin.

High-resolution, precision mapping of seagrass blue carbon habitat using multi-spectral imaging and aerial LiDAR

Blue carbon ecosystems, particularly seagrass meadows, provide a myriad of critical ecosystem services through their role in supporting biodiversity, protecting shorelines, and sequestering and storing carbon. Despite their increased recognition for advancing global marine conservation efforts, our knowledge of the location and spatial extent of seagrass ecosystems globally remains relatively poor, due to the logistical and operational challenges of accurately mapping seafloor habitat using remote sensing techniques. Here we develop and validate an aerial LiDAR approach for mapping tropical seagrass blue carbon habitat in The Bahamas, by integrating full waveform bathymetric LiDAR with multi-spectral imaging. The results demonstrate accuracies between 92 and 98% for predicting seagrass types, over an extensive (e.g., >1000 km2) study area whilst utilizing robust ground-truthing techniques. These findings demonstrate the value of the aerial LiDAR approach used here for ongoing bathymetric surveys of seagrass habitat in The Bahamas and throughout similar ecosystems in the wider Caribbean, which should provide key insights for coastal management and conservation efforts.

Deep seafloor hydrothermal vent communities buried by volcanic ash from the 2022 Hunga eruption

Mass mortality of marine animals due to volcanic ash deposition is present in the fossil record but has rarely been documented in real time. Here, using remotely-operated vehicle video footage and analysis of ash collected at the seafloor, we describe the devastating effect of the record-breaking 2022 Hunga submarine volcanic eruption on endangered and vulnerable snail and mussel species that previously thrived at nearby deep-sea hydrothermal vents. In contrast to grazing, scavenging, filter-feeding, and predatory vent taxa, we observed mass mortality, likely due to smothering during burial by thick ash deposits, of the foundation species, which rely on symbiotic chemosynthetic bacteria for the bulk of their nutrition. This is important for our broad understanding of the natural disturbance of marine ecosystems by volcanic eruptions and for predicting the effects of anthropogenic disturbance, like deep-sea mining, on these unique seafloor habitats.

Closing the data gap – Automated seafloor health maps to accelerate nature-based solutions

This article delves into the pivotal role of the oceans, specifically the seafloor, in addressing climate change and food security. Despite its significance, a lack of detailed data on the seafloor hampers informed decision-making by policymakers, impedes sustainable blue economy investments, and hinders the development of blue carbon and biodiversity credit markets. PlanBlue, an innovative technology company, has devised a groundbreaking solution using advanced imaging, underwater navigation, and machine learning to automate seafloor mapping. This article explores the importance of seafloor data, the barriers to access data, and how PlanBlue's technology can improve our understanding of the ocean's potential. The discussion encompasses the significant role of the seafloor as a carbon sink, the necessity for credible data in ocean conservation, and the crucial link between seafloor mapping and effective marine spatial planning. PlanBlue's innovative approach not only adds speed and scale to data collection but also provides multi-layered insights into species health, biomass, and more, contributing to the credibility of marine conservation efforts. The article concludes with a scientific review highlighting the accuracy and meaningfulness of PlanBlue's methodology, validating its transformative impact on the blue carbon industry and seafloor habitat monitoring.

Quantifying Uncertainty in Sustainable Biomass and Production of Biotic Carbon in Enceladus' Notional Methanogenic Biosphere

AbstractBeneath Enceladus' ice crust lies an ocean which might host habitable conditions. Here, the scale and productivity of a notional Enceladean methanogenic biosphere are computed as a function of the core‐to‐ocean flux of hydrogen and the ratio between abiotic and biotic methane in Enceladus' space plume. Habitats with an ocean‐top pH range of 8–9 have up to 40%–60% probability of being energy‐limited. Those at pH &gt; 9 are increasingly uninhabitable, and those &lt;8.5 are increasingly likely to host exponential growth, possibly leading to compositional inconsistencies between the ocean and Cassini gas observations. In those cases, energy‐based habitability models cannot infer an inhabited Enceladus consistent with both Earth life and Cassini measurements without including additional microbial growth limiters such as nutrient limitation, toxicity, or spatial constraints. If methanogens are isolated to a 350 K seafloor habitat and consume 10 mol s−1 of H2, the most probable biomass is 103, 103.7 kg C with ocean‐top pH 8,9, respectively. Biomass production consistent with space plume fluxes is 104–106 kgC yr−1—milligrams of cellular carbon per kilogram of H2O ejected—but requires that &gt;50% of the space plume methane is biotic. Alternative scenarios are presented, and biomass is generally lower when habitat temperature is higher. Ocean biomass density cannot yet be reliably estimated owing to uncertainties in the scale and physicochemical properties of Enceladus' putative habitats. Evaluating abiotic to biotic ratios in plume methane and organic material could help identify false negative results from life detection missions and constrain the scale of an underlying biosphere.

Sediment discharge from Greenland’s marine-terminating glaciers is linked with surface melt

Sediment discharged from the Greenland Ice Sheet delivers nutrients to marine ecosystems around Greenland and shapes seafloor habitats. Current estimates of the total sediment flux are constrained by observations from land-terminating glaciers only. Addressing this gap, our study presents a budget derived from observations at 30 marine-margin locations. Analyzing sediment cores from nine glaciated fjords, we assess spatial deposition since 1950. A significant correlation is established between mass accumulation rates, normalized by surface runoff, and distance down-fjord. This enables calculating annual sediment flux at any fjord point based on nearby marine-terminating outlet glacier melt data. Findings reveal a total annual sediment flux of 1.324 + /− 0.79 Gt yr-1 over the period 2010-2020 from all marine-terminating glaciers to the fjords. These estimates are valuable for studies aiming to understand the basal ice sheet conditions and for studies predicting ecosystem changes in Greenland’s fjords and offshore areas as the ice sheet melts and sediment discharge increase.

Implications of increased intertidal inundation on seagrass net primary production

Seagrass meadows are productive and functionally important seafloor habitats that are declining in many parts of the world under pressure from human activities. Seabed light availability is inversely related to water depth, thus sea level rise associated with global warming may impinge upon seagrass productivity and its contributions to coastal ecosystems. Across natural variation in seagrass bed depth driven by tidal oscillations and distance from shore, we quantified seafloor oxygen exchange every 15 min for three days and nights at sites in New Zealand using aquatic eddy covariance to better understand the implications of sea level rise on shallow seagrass. Four sites of differing mean depth (1.5–4.0 m deep at high tide) were net producers of oxygen when photosynthetically active radiation at the seabed was >87.5 μmol photons m−2 s−1, with net oxygen production >4 mmol m−2 h−1 at all sites during peak sunlight hours. The effect of light attenuation on dissolved oxygen production was evident when comparing fluxes in the morning (low tide) and evening (high tide), with relatively similar incident light levels arriving at water surface at these times of day. The shallowest site was expected to receive the greatest amount of light at the seabed and be most productive. However, the second shallowest site was the most productive, due to higher seagrass cover and clearer water (less light attenuation in the water column). Higher cover of seagrass likely reduced sediment resuspension while increasing photosynthetic capacity (i.e., more photosynthetic biomass). The existence of turbid fringes of water near the upper shore and climate-related shifts in suspended sediment concentrations may interfere with predictions of shoreward migration of seagrass meadows, which are already complicated by interactions with upper intertidal vegetation (e.g., mangroves) and human built structures (e.g., seawalls).

Bycatch Mitigation Strategies in the Gulf of Alaska

Commercial fishing is a crucial industry in Alaska’s economy, but unsustainable fishing practices, especially bottom trawling, lead to excessive bycatch and economic discards. This poses a major threat to marine ecosystems and their biodiversity, which puts the resources within Alaska’s fisheries at risk of diminishing to a point where they cannot meet human demand. Through extensive research and evaluation of this issue and existing legislation that governs Alaska’s fisheries, we recommend the full implementation of two specific measures across all of Alaska’s fisheries. One is electronic monitoring on all vessels in the form of deep learning cameras, and the other is a “freeze the footprint” approach on bottom trawling, which protects key seafloor habitats within the existing area that has been damaged by previous trawling activity. These efficient methods are a safer alternative to on-site observation, and they will lead to a healthier seafloor ecosystem, which is essential for marine life. Alaskan communities rely on their fisheries, and maintaining healthy marine ecosystems is critical to economic stability.

Modelled broad-scale shifts on seafloor ecosystem functioning due to microplastic impacts on bioturbation

Bioturbating species play an essential role in regulating nutrient cycling in marine sediments, but their interaction with microplastics (MP) remains poorly understood. Here we investigated the linkage between MP and ecosystem functioning using experimental observations of luminophore distribution in the sediment to parametrize bioturbation coefficients (Db). this information as fed into a simplified transport-reaction model, allowing us to upscale our experimental results. We found that the composition of bioturbators modulated shifts in the ecosystem functioning under microplastic stress. Maldanid worms (Macroclymenella stewartensis), functionally deep burrowing and upward-conveyor belt feeders, became less active. The Db of M. stewartensis reduced by 25% with the addition of 0.002 g MP cm−2 at surface sediment, causing accumulation of organic matter in the oxic sediment zone and stimulating aerobic respiration by 18%. In contract, the tellinid bivalve Macomona liliana, functionally a surface -deposit feeder that excretes at depth, maintained particle mixing behaviour in MP-contaminated systems. This study provides a mechanistic insight into the impacts of MP and indicates that the functional role of bioturbating species should be involved in assessing the global impact of MP. The model allowed us to understand the broad-scale impact of MP on seafloor habitat.

Implications of transient methane flux on associated biological communities in high-arctic seep habitats, Storbanken, Norwegian Barents Sea

The continental margins of the Arctic Ocean basin contain methane seeps, where transient fluxes of seafloor methane are released due to the thermal dissociation of gas hydrates. An increase in shallow methane seeps identified over the past decade, potentially due to enhanced warming of the Arctic Ocean bottom water and associated destabilization of hydrate structure. Biological communities associated with methane release east of Svalbard in the Barents Sea (Storbanken Crater site, 76° 46.7′N, 35° 43.5′E, depths between 120 m–300 m depths) were investigated using towed camera imagery and ship-based platforms during a 2017 CAGE17-2 cruise on the RV Helmer Hanssen. We analyzed relationships among methane flux data, seafloor habitat characteristics, and biological community structure (i.e., presence and distribution of megafauna and expression of microbial mats) from a total of 14 surveys (6827 images and 40 multicore sediment cores) within the Storbanken Crater area and compared it to 2015 data. Unlike seep expressions at deeper sites (∼1200 m) in the Norwegian margin region, no seep-endemic, chemosynthetic-associated megafaunal species were observed at the shallow surveyed sites and all sites hosted similarly diverse communities of non-seep species, including commercially important fish and crustaceans. Methane concentrations did not markedly differ between the crater and non-crater sites. Rates of methane gas advection through sediments (in the form of flares) were relatively low and concentration of methane was even lower in porewater samples at the crater site. We present the first evidence of methane flare flux and intermittent microbial mat distribution with associated folliculinid ciliates, which suggests a long history of methane emissions and a transient seep environment in spatial and temporal flux. Together, this study presents a critical baseline on the temporal release of arctic methane and benthic biological communities to initiate temporal studies that identify future changes and predict the impact of climate change.

Habitat mapping of Portugal’s north-western continental shelf and its application to implement the European Marine Strategy Framework Directive

Seafloor habitat maps allow to integrate various data layers and compare areas, being valuable tools for assessing environmental quality. Although the European Nature Information System (EUNIS) was created to catalogue habitats throughout Europe, its use in ecological assessment is relatively uncommon. This work proposes a EUNIS, level 5, benthic habitats map for the Portuguese continental shelf North of Nazaré canyon. Seven EUNIS level 5 habitats were identified, of which six were new to EUNIS, as this catalogue is less complete for southern Europe. Hereafter this map was used to assess the environmental status (ES) within the Marine Strategy Framework Directive (MSFD), which was developed to help European Union countries achieve a good environmental status (GES) in their marine ecosystems. In this sense, eleven quality descriptors (and respective criteria) were set to assess the environmental status (ES), which can be performed using diverse indicators. In this study, the ES status was assessed for two of such descriptors, namely D1, Biodiversity, which was assessed using the Marine Biological Value (MBV); and D6, Seafloor Integrity, which was assessed through the AZTI Marine Biotic Index (AMBI) and Multivariate-AMBI (M-AMBI). For both descriptors, an overall GES (or higher) was determined for this study area. These results set a baseline for future ES assessments within the MSFD, while the use of the EUNIS habitat maps can be expanded to assess the ES of other descriptors, namely D2, non-indigenous species, D3, commercially exploited fish and shellfish and D4, food webs.

Integrating habitat features into spatio-temporal biomass dynamics models for a better understanding of stock productivity: a case study of sea scallop in the Bay of Fundy

Abstract Recent efforts in ocean mapping of seafloor habitat have made data increasingly available. For bottom-dwelling and/or sessile species, there is often a strong relationship between population productivity and habitat, and stock assessment models are likely to be improved by the inclusion of habitat. Here, we extend a recently developed spatio-temporal biomass dynamics model to allow habitat to inform probabilities of non-zero tows and catchability. Simulation experiments demonstrate the ability of this new approach to reliably capture population trends over time and space, with the applicability of the method further demonstrated using data from the Canadian Maritimes Inshore Sea Scallop Fishery in the Bay of Fundy. This habitat-informed spatio-temporal biomass dynamics model better captures underlying processes, reduces uncertainty, thereby improving our understanding of stock status from which fisheries management decisions can be based.

Characterization and differentiation of sublittoral sandbanks in the southeastern North Sea

Marine sublittoral sandbanks are essential offshore feeding grounds for larger crustaceans, fish and seabirds. In the southern North Sea, sandbanks are characterized by considerable natural sediment dynamics and are subject to chronic bottom trawling. However, except for the Dogger Bank, sandbanks in the southeastern North Sea have been only poorly investigated until now. We used an extensive, multi-annual dataset covering ongoing national monitoring programmes, environmental impact assessments, and basic research studies to analyse benthic communities on sublittoral sandbanks, evaluating their ecological value against the backdrop of similar seafloor habitats in this region. The analysis revealed complex spatial structuring of sandy seafloor habitats of the southeastern North Sea. Different infauna clusters were identified and could be specified by their composition of characteristic species. The sandbanks shared common structural features in their infauna community composition although they were not necessarily characterized by particularly high biodiversity compared to other sandy habitats. A close association of one of the main bioturbators in the southern North Sea, the sea urchin Echinocardium cordatum, with sandbanks was detected, which may promote the sediment-bound biogeochemical activity in this particular seafloor habitat. This would corroborate the status of sandbanks as sites of high ecological value calling for consideration in marine conservation.

Analysis-ready optical underwater images of Manganese-nodule covered seafloor of the Clarion-Clipperton Zone

We provide a sequence of analysis-ready optical underwater images from the Clarion-Clipperton Zone (CCZ) of the Pacific Ocean. The images were originally recorded using a towed camera sledge that photographed a seabed covered with polymetallic manganese-nodules, at an average water depth of 4,250 meters. The original degradation in visual quality and inconsistent scale among individual raw images due to different altitude implies that they are not scientifically comparable in their original form. Here, we present analysis-ready images that have already been pre-processed to account for this degradation. We also provide accompanying metadata for each image, which includes their geographic coordinates, depth of the seafloor, absolute scale (cm/pixel), and seafloor habitat class obtained from a previous study. The provided images are thus directly usable by the marine scientific community e.g., to train machine learning models for seafloor substrate classification and megafauna detection.

Indications of marine benthos occurrence from multi-spectral multi-beam backscatter data: a case study in the North Sea

To facilitate the conservation of seafloor habitats and planning of offshore activities, there is a growing need for mapping marine benthos in an effective and efficient way. Acoustic data acquired by multi-beam echosounders (MBES) have been extensively used for large-scale and high-resolution seafloor characterization. A deeper understanding of the relationship between backscatter data and sediment compositions can help to identify the benthos occurrence from the MBES data. With two multi-spectral MBES datasets collected near the western Wadden Sea islands in the North Sea, we investigated the potential of mapping marine benthos through backscatter classification. Two unsupervised classification methods, i.e., Bayesian classification, which mainly exploits the backscatter strength from incident angles larger than 20°, and hierarchical clustering of the backscatter strength at different angular ranges, were employed and the results were compared. The classification results from both methods showed a good correspondence with sediment properties such as the median grain size. Moreover, based on a principal component analysis of bottom sample properties, the hierarchical clustering results indicated a better distinction between contributions from the gravel content and benthos occurrence, e.g., sand mason worm density, than Bayesian classification, through involving the backscatter angular variations. Classification for multiple frequencies, on the other hand, showed little difference regarding the relationship with bottom sample properties. Although the backscatter difference between frequencies was also found to positively correlate with certain sample properties, using multi-spectral features for acoustic classification in this study did not reveal additional information compared to single-frequency classification results.

Reduced efficiency of pelagic–benthic coupling in the Arctic deep sea during lower ice cover

Pelagic–benthic coupling describes the connection between surface-water production and seafloor habitats via energy, nutrient and mass exchange. Massive ice loss and warming in the poorly studied Arctic Chukchi Borderland are hypothesized to affect this coupling. The strength of pelagic–benthic coupling was compared between 2 years varying in climate settings, 2005 and 2016, based on δ13C and δ15N stable isotopes of food-web end-members and pelagic and deep-sea benthic consumers. Considerably higher isotopic niche overlap and generally shorter isotopic distance were found between pelagic and benthic food web components in 2005 than in 2016, suggesting weaker coupling in the latter, low-ice year. δ15N values indicated more refractory food consumed by benthos in 2016 and fresher food reaching the seafloor in 2005. Higher δ13C values of zooplankton indirectly suggested a higher contribution of ice algae in 2005 than 2016. The difference in pelagic–benthic coupling between these years is consistent with higher energy retention within the pelagic system, perhaps due to strong stratification in the Amerasian Basin in the recent decade. Weaker coupling to the benthos can be expected to continue with ice loss in the study area, perhaps reducing benthic biomass and remineralization capacity; monitoring of the area is needed to confirm this prediction.

Mapping warming reefs—An application of multibeam acoustic water column analysis to define threatened abalone habitat

Robust definition of the spatial extent of seafloor habitats and how they may be changing through time is a holy grail for ecosystem management, particularly if an ecosystem is approaching a tipping point beyond which irreversible changes may occur. Here we generate and explore a new data set for the management of warming reefs in eastern Tasmania, Australia that will significantly improve the baseline maps required for fine-scaled spatial modelling and management that is, both robust at regional scales and is highly resolved within the water column. This procedure enabled the relative density of kelp vegetation to be identified in a region that is being overwhelmed by the range extension of a destructive grazer, the Longspined Sea Urchin, Centrostephanus rodgersii. We present a new online tool to visualize multibeam water column acoustic data as surfaces of kelp density at high resolution (50 cm) scale over seafloor terrain maps (spanning a total straight-line distance of 594 km and a total area of 29.14 km2) to reveal the types of reef structure on the East Coast of Tasmania where abalone habitat is threatened by kelp loss.