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Rhodolith beds, recognized as biodiversity hotspots with high ecological and conservation importance, face local anthropic pressures, including trawl fishing. However, monitoring the diversity associated with this sensitive biogenic habitat in the deep waters of the Mediterranean Sea is challenging.Traditional monitoring methods, such as experimental trawling and trammel nets, are extractive and have sampling limitations in providing comprehensive diversity inventories. In this work, we explore three alternative techniques (still video cameras, environmental DNA [eDNA] and bioacoustics) to monitor fish assemblages associated with rhodolith beds in the Menorca Channel at 45–80 m depth.Ten sites were surveyed with eDNA, and 66 fish taxa were identified, including endangered sharks and cryptic species. The molecular operational taxonomic units (MOTUs) richness varied significantly according to habitat heterogeneity, being higher in homogeneous bottoms, and to exposure to trawling, with higher richness in non‐exposed areas.Bioacoustics, though limited by a reduced library of fish sounds, detected differences in sound richness between habitat types, and the highest abundance of sounds was recorded in the areas with the greatest small‐scale habitat heterogeneity.Underwater video revealed limitations in species detection but proved effective for characterizing small‐scale habitat types and heterogeneity.In summary, each technique provides valuable information at different spatial scales and levels of detail. To assess the feasibility of these techniques for long‐term monitoring, we explored their capabilities and limitations in terms of costs, survey logistics and data output. [ABSTRACT FROM AUTHOR]

Biogenic habitats are foundational habitats for species assemblages and drive a range of ecosystem functions. The Hauraki Gulf/Tiikapa Moana is the most intensively used coastal area in Aotearoa/New Zealand, and decades of commercial fishing, sedimentation and industrialization have degraded biogenic habitats in the Gulf. In response, the marine spatial plan 'Sea Change' includes proposals to create new and extend existing marine protected areas (MPAs) and restrict the area open to mobile bottom‐impact fishing methods to conserve and help the recovery of biogenic habitats.To assess the benefits of different spatial planning scenarios for biogenic habitats, information on their spatial distribution is needed, but data limitations are a significant challenge. Here, an approach is detailed that maximized the information extracted from limited species occurrence data, by incorporating expert knowledge to develop and evaluate models of biogenic habitat‐forming taxa.Ensemble habitat suitability models (using boosted regression tree and random forest models) were created for 20 biogenic habitat groups. Using withheld data for validation, area under curve (AUC) scores ranged from 0.58 to 0.95 and true skill statistics (TSS) ranged from 0.37 to 0.84, though three models were further evaluated as insufficient representations of known ecological habitats by expert assessors.Models produced here provide substantially increased information to inform progress on implementation of the Sea Change plan. Two stakeholder processes have been held, resulting in the development of spatial plans for bottom trawl mitigation that are currently under public consultation. Systematic surveys that gather abundance and high‐resolution environmental data should be a priority to improve the utility of predictive models and inform future management processes in the Hauraki Gulf, and funding has been allocated to support additional data collection to determine the effectiveness of spatial management measures in the Hauraki Gulf. [ABSTRACT FROM AUTHOR]

Long‐term monitoring programs are fundamental to detect changes in ecosystem health and understand ecological processes. In the current context of increasing anthropogenic threats on marine ecosystems, understanding the dynamics and response of communities becomes essential. We used data collected over 14 years in the REBENT benthic coastal invertebrates monitoring program, at a regional scale in the North‐East Atlantic, covering a total of 26 sites and 979 taxa. Four distinct habitats were studied: two biogenic habitats associated with foundation species in the intertidal and subtidal zones and two bare sedimentary habitats in the same respective tidal zones. We used community trajectory analysis (CTA), a statistical approach that allows for quantitative measures and comparisons of temporal trajectories of ecosystems. We compared observed community trajectories to trajectories simulated under a non‐directional null model in order to better understand the dynamics of the communities, their potential drivers, and the role of the studied habitats in these dynamics. Despite strong differences in the community compositions between sites and habitats, the communities followed non‐directional dynamics during the 14 years monitored, which suggested stability at the regional scale. However, the shape, size, and direction of the trajectories of benthic communities were more similar within than among habitats, also suggesting the influence of the nature of the habitat on community dynamics. Results showed a higher variability in community composition the first years of the monitoring in the intertidal bare habitat and confirmed the role of biogenic habitats in maintaining temporal stability. They also highlighted the need to apprehend the role of transient and rare species and the scale of observation in temporal beta diversity analyses. Finally, our study confirmed the usefulness of CTA to link observed trajectory patterns to fundamental ecological processes. [ABSTRACT FROM AUTHOR]

The Sea Change—Tai Timu Tai Pari Hauraki Gulf Marine Spatial Plan is New Zealand's first marine spatial plan and represents a collaborative response from mana whenua, local stakeholders, and regional and national governmental agencies to the threats and stressors responsible for the declining natural state of the Hauraki Gulf ecosystems. From a biodiversity perspective, the main objectives of the plan are the recovery of depleted fishing stocks and the restoration of degraded marine habitats through a network of marine protected areas (MPAs), including highly protected areas that allow for customary practices. While some information on biodiversity, resource activities, and management layers was used to develop the MPA network proposals, they were developed without benefit of systematic conservation planning tools. Here, systematic conservation planning software was used to assess the conservation benefits of different no‐take MPA network proposals, using available biodiversity and habitat datasets. The analysis indicates that while the proposed MPAs provide protection for some biodiversity features that were identified by the stakeholders, the inclusion of newly available biodiversity datasets under a systematic conservation planning approach could improve conservation outcomes. [ABSTRACT FROM AUTHOR]

Addressing growing threats of overexploitation to the world’s oceans is especially challenging in the High Seas, where limited data and international jurisdiction make it difficult to determine where and when conservation measures are necessary. Of particular concern are vulnerable marine ecosystems (VMEs)—special habitats on the seafloor that are highly sensitive to disturbance and slow to recover. To ensure the long-term conservation and sustainable use of marine resources, regional fisheries management organizations are committed to identifying the locations of VMEs and responding to prevent significant adverse impacts (SAIs). For over 50 years, Cobb Seamount—a shallow underwater volcanic mountain in the Northeast Pacific Ocean—has been commercially fished by multiple nations using various types of gear. Here we have assimilated data from fisheries records and a recent visual survey on the seamount. Our findings show a variety of habitat-forming emergent biological structures widely distributed on Cobb Seamount and generally depth-stratified into high-density assemblages (≥1 m–2). Our spatial analyses show that fishing has also been widely distributed, overlapping the habitat of the biological structures. We found fewer cold-water corals, sponges, and other biological structures in areas with higher recent fishing effort and documented evidence of fishing impacts, such as extensive mats of coral rubble and a high abundance of derelict fishing gear entangled with dead or damaged organisms. Based on the average density of “lost” gear (2,785 ± 1,003 km–2), we can confidently estimate that hundreds of thousands of items of derelict fishing gear are currently entangled with the seafloor of Cobb Seamount and that these pose an ongoing threat to biological structures, the biogenic habitats they create, and the species they support. Such impacts can persist for decades or centuries to come. This study contributes and discusses new information on the condition and distribution of biological structures, VME indicator taxa, physically complex biogenic ecosystems, and human impacts on Cobb Seamount. These data will be necessary to identify the location(s) of potential VMEs and SAIs on this heavily fished seamount in the High Seas.

Lithophyllum species in the Mediterranean Sea function as algal bioconstructors, contributing to the formation of biogenic habitats such as coralligenous concretions. In such habitats, thalli of Lithophyllum, consisting of crusts or lamellae with entire or lobed margins, have been variously referred to as either one species, L. stictiforme, or two species, L. stictiforme and L. cabiochiae, in the recent literature. We investigated species diversity and phylogenetic relationships in these algae by sequencing three markers (psbA and rbcL genes, cox2,3 spacer), in conjunction with methods for algorithmic delimitation of species (ABGD and GMYC). Mediterranean subtidal Lithophyllum belong to a well‐supported lineage, hereby called the L. stictiforme complex, which also includes two species described from the Atlantic, L. lobatum and L. searlesii. Our results indicate that the L. stictiforme complex consists of at least 13 species. Among the Mediterranean species, some are widely distributed and span most of the western and central Mediterranean, whereas others appear to be restricted to specific localities. These patterns are interpreted as possibly resulting from allopatric speciation events that took place during the Messinian Salinity Crisis and subsequent glacial periods. A partial rbcL sequence from the lectotype of L. stictiforme unambiguously indicates that this name applies to the most common subtidal Lithophyllum in the central Mediterranean. We agree with recent treatments that considered L. cabiochiae and L. stictiforme conspecific. The diversity of Lithophyllum in Mediterranean coralligenous habitats has been substantially underestimated, and future work on these and other Mediterranean corallines should use identifications based on DNA sequences. [ABSTRACT FROM AUTHOR]

Rhodolith beds represent a key habitat worldwide, from tropical to polar ecosystems. Despite this habitat is considered a hotspot of biodiversity, providing a suite of ecosystem goods and services, still scarce quantitative information is available thus far about rhodolith beds occurrence and ecological role, especially in the Mediterranean Sea. This study reports the composition and patterns of distribution of rhodolith assemblages found in four study areas along ca. 860 km of coast in the Central Mediterranean Sea. These rhodolith beds were studied for the first time and significant differences at all spatial scales have been highlighted, documenting the high variability of this habitat. Rhodolith species composition, morphology and distribution have been discussed considering the potential role of environmental factors in driving these patterns. The need for improving their protection is discussed to complement present conservation and management initiatives, particularly in the frame of the EU Marine Strategy Framework Directive.

Rhodolith beds (RBs) are bioconstructions characterized by coralline algae, which provide habitat for several associated species. Mediterranean RBs are usually located in the mesophotic zone (below 40 m), and thus are frequently remote and unexplored. Recently, the importance and vulnerability of these habitats have been recognized by the European Community and more attention has been drawn to their investigation and conservation. This study reports the results of an extensive monitoring program, carried out within the Marine Strategy Framework Directive (2008/56/EC), in six sites off the Campania coast (Italy, Mediterranean Sea). New insights were given into the distribution, cover, vitality (i.e., live/dead rhodolith ratio), structural complexity, and coralline algae composition of RBs. Remotely operated vehicles (ROV) investigations allowed the description of several RBs, and the discovery of a RB with rhodolith cover >65% offshore the Capri Island. Only two sites (Secchitiello and Punta Campanella) showed a very low mean cover of live rhodoliths (Lithothamnion dominated all sites, and Phymatolithon calcareum and Lithothamnion corallioides, protected by the Habitats Directive (92/43/EEC), were detected in all RBs.

Abstract: Latitudinal and elevational temperature gradients (LTG and ETG) play central roles in biogeographical theory, underpinning predictions of large‐scale patterns in organismal thermal stress, species' ranges and distributional responses to climate change. Yet an enormous fraction of Earth's taxa live exclusively in habitats where foundation species modify temperatures. We examine little‐explored implications of this widespread trend using a classic model system for understanding heat stresses – rocky intertidal shores. Through integrated field measurements and laboratory trials, we demonstrate that thermal buffering by centimetre‐thick mussel and seaweed beds eliminates differences in stress‐inducing high temperatures and associated mortality risk that would otherwise arise over 14° of latitude and ~ 1 m of shore elevation. These results reveal the extent to which physical effects of habitat‐formers can overwhelm broad‐scale thermal trends, suggesting a need to re‐evaluate climate change predictions for many species. Notably, inhabitant populations may exhibit deceptive resilience to warming until refuge‐forming taxa become imperiled. [ABSTRACT FROM AUTHOR]

Metacommunity theory highlights the potential of β-diversity as a useful link to empirical research, especially in diverse systems where species exhibit a range of stage-dependent dispersal characteristics. To investigate the importance of different components and scales of β-diversity in community assembly, we conducted a large-scale disturbance experiment and compared relative recovery across multiple sites and among plots within sites on the rocky shore. Six sites were spread along 80 km of coastline and, at each site, five plots were established, matching disturbed and undisturbed quadrats. Recovery was not complete at any of the sites after 1 year for either epibenthos (mostly composed of macroalgae and, locally, mussels) or infauna. Significant differences in recovery among sites were observed for epibenthos but not for infauna, suggesting that different community assembly processes were operating. This was supported by epibenthos in the recovering plots having higher species turnover than in undisturbed sediment, and recovery well predicted by local diversity, while infaunal recovery was strongly influenced by the epibenthic community's habitat complexity. However, infaunal community recovery did not simply track formation of habitat by recovering epibenthos, but appeared to be overlain by within-site and among-site aspects of infaunal β-diversity. These results suggest that documenting changes in the large plants and animals alone will be a poor surrogate for rocky shore community assembly processes. No role for ecological connectivity (negative effect of among-site β-diversity) in driving recovery was observed, suggesting a low risk of effects from multiple disturbances propagating along the coast, but a limited resilience at the site scale to large-scale disturbances such as landslides or oil spills.

Seascapes contain a mosaic of ecosystem types, including ‘small natural features’ that support a diverse fauna and flora, and provide ecosystem services disproportionate to their size. These include tropical coral reefs, seagrass meadows, rhodolith beds, kelp and mangrove forests as well as deep-sea coral reefs, sponge gardens and hydrothermal vents. The contributions of coral reefs, mangrove forests and seagrass meadows are well recognised as important components of tropical marine seascapes. In temperate regions, hotspots of primary productivity such as kelp forests, and vegetation-based ecosystems found at coastal margins play significant roles in nutrient and sediment trapping and coastal protection. Biogenic features in coastal regions can also play important roles, including shellfish reefs, sponge gardens and macroalgal mats that provide physical structure within soft sediment ecosystems. Similar biogenic features are found in the deep sea, which often occur associated with seamounts, canyon features, cold seeps and hydrothermal vents. Many marine small natural features are globally threatened as they are found at the interface with human-influenced landscapes (coastal ecosystems) or are the focus of resource exploitation (e.g., trawling for fish associated with seamounts and canyons). Challenges in management are, however, consistent across depths, and highlight the restricted spatial extent of such features, and the limited information typically available on their distributions, and the ecosystem services they provide. Numerous strategies can be utilized to sustainably manage, protect, create and restore these marine small natural features and their associated biodiversity. [ABSTRACT FROM AUTHOR]

Macroalgal communities of coastal ecosystems play a key role in maintaining overall coastal biodiversity. In this study, habitat preference (macroalgal host preference) and temporal changes (season) of epifaunal communities associated to five macroalgal species such as Padina, Sargassum, Ulva, Acanthophora and Gracilaria were observed at seasonal intervals (summer and winter) for 2 years from May 2012 to March 2014 on the Jeddah coastal waters of the Red Sea. Major epifaunal groups observed included polychaetes, amphipods, isopods, gastropods, mussels and crabs. Polychaetes were represented by 10 species followed by amphipods with five species. The abundance of gastropods, polychaetes and mussels showed significant variation between the macroalgae irrespective of morphology. Generally, the abundance of these taxa were high on Padina and low on Sargassum. Significant seasonal changes were observed on the abundance of polychaetes, amphipods and isopods. The abundance of some epifaunal groups showed a significant relationship with environmental parameters such as surface water temperature, salinity, pH and dissolved oxygen content. [ABSTRACT FROM PUBLISHER]

Deep-sea ecosystems have attracted considerable commercial interest in recent years because of their potential to sustain a diverse range of mankind's industrial needs. If these systems are to be preserved or exploited in a sustainable manner, mapping habitats and species distributions is critical. As biodiversity at cold-seeps or other deep-sea ecosystems is driven by habitat heterogeneity, imagery is the obvious choice for characterizing these systems and has indeed proven extremely valuable towards mapping biogenic habitats formed by dense aggregations of large sized species, such as coral reefs, tubeworm bushes or bivalve beds. However, the acquisition of detailed images with resolution sufficient for reliable identification is extremely time consuming, labor intensive and highly susceptible to logistical issues. We developed a novel method for quickly mapping cold seep fauna and habitats over large areas, at the scale of squares of kilometers. Our method uses multibeam echosounder bathymetry and acoustic backscatter data, both segmented and reclassified based on topographical features and then combined to obtain a raster containing unique values incorporating both backscatter and bathymetry data. Two datasets, obtained from 30 m and 8 m above the seafloor were used and the results from the two datasets were compared. The method was applied to a cold seep community located in a pockmark in the deep Congo channel and we were able to ground truth the accuracy of our method against images of the area. The two datasets, obtained from different altitudes gave varying results: the 8 m altitude dataset reliably predicted tubeworms and carbonate rock, while the 30 m altitude dataset predicted tubeworms and vesicomyid clams. The 30 m dataset was more accurate than the 8 m altitude dataset in predicting distributions of tubeworms. Overall, all the predictions were quite accurate, with at least 90% of predictions being within 5 m of real distributions. [ABSTRACT FROM AUTHOR]

The boreal bivalveModiolus modiolusis common subtidally where it aggregates to form extensive, long-lived, biogenic habitats with a diverse associated flora and, especially, fauna. Despite this ecological importance,M. modiolushas not been described in terms of its functional morphology and overall biology.Modiolus modiolusis a typical epibenthic, suspension-feeding mytilid, albeit with anatomical modifications adapting it to a partially buried, gregarious lifestyle in a stable environment experiencing medium–high energy levels. The juvenile shell is covered partly in byssal setae secreted by the byssal gland and foot complex and becomes covered in sand grains held in place by a mucoid cement secreted by the dorsal mantle. The camouflaged shell at this vulnerable time probably serves as an anti-predator device. Individuals grow to maximum shell lengths of ∼60–213 mm, depending on depth and locality. With age (≥ 20–45 years), shells often become deformed, particularly posteriorly and around the byssal gape, thereby increasing reproductive capacity (gonadal volume) without increasing somatic growth. Information on the biology, reproductive strategy and life history traits ofM. modiolusare reviewed. These field- and laboratory-derived data provide us with essential information to aid future research into the protection and conservation of this ecologically important biogenic habitat. This is because, today, dredging and fishery activities using bottom-towed gear have seriously damaged severalM. modiolushabitats with deleterious impacts on ecosystem functioning. Post-impact recovery times are slow and dependent on both local and mega-population distributions. [ABSTRACT FROM AUTHOR]

In the face of declining ocean health and marine biodiversity, marine management arrangements may need to change in many jurisdictions. This can occur in a planned process of legislative and institutional reform undertaken by central government, or by an incremental and ad hoc 'unplanned' process through court decisions or local actions. In either case, targeted characterisations of the contemporary regulatory seascape are necessary to accurately diagnose what system elements may need major change to address ecological degradation. In this study, we examine the regulatory and institutional interplay between central government, sub-national regional authorities, and Indigenous Māori in the protection and management of marine biogenic habitats in New Zealand. Based on an analysis of government documents, institutional responses to a set of questions, and recent case law, we found generic institutional failings to implement core legislation, at both sub-national 'regional' and national scales. In particular, less than half of the regional authorities had given effect to a mandatory national instrument that set environmental bottom-lines, and central government failure to identify and protect significant fisheries habitats. Concurrently, we identified an upsurge in requests for temporary fishing closures through rāhui (traditional customary prohibitions), and the potential for tools enabled in customary marine tenure legislation to play a significant future role in managing marine ecosystem health. Our study highlights that the regulatory seascape is devolving towards a greater polycentricity of management with an increased involvement of Māori at sub-national and local levels, which may hold lessons for Indigenous peoples in other jurisdictions. These 'unplanned reforms' are likely to be a key driver of improvements in the management and governance of biodiverse marine biogenic habitats at national and sub-national level, both prior to, and as a consequence of, the New Zealand Government's planned ocean reform programme. [ABSTRACT FROM AUTHOR]

Pennatulacean octocorals (sea pens), one of the primary conservation targets of the Laurentian Channel Marine Protected Area (MPA) in eastern Canada, occur at high densities in some deep-sea sedimentary habitats. Considered important habitat-forming organisms for many megafaunal organisms, the effect of sea pens on nearby sedimentary macrofaunal communities remains unexplored. During two cruises in September 2017 and July 2018, we sampled 9 stations within the MPA (336-445 m depth), including sea pen fields and bare sedimentary habitats, targeting individual sea pens in a subset of the cores to assess small-scale effects. We evaluated macrofaunal density, taxonomic diversity, vertical distribution, community composition, and biological trait expression, and investigated variation between sea pen fields and other (bare) sedimentary habitats, as well as between cores with and without sea pen specimens. Using multivariate analyses, we identified abiotic and biotic drivers of macrofaunal community composition and biological trait expression. Enhancement of macrofaunal density and taxonomic diversity and higher percentages of organisms in the upper sediment layers characterized sea pen fields in autumn, with more variable results in summer. Community composition and biological trait expression consistently differed in sea pen fields compared to bare sedimentary habitats, with Pennatula sea pen density as one of the primary drivers of variation especially for community composition, along with other environmental drivers (depth, grain size, and organic matter quantity and quality). We also detected small-scale enhancement of macrofaunal diversity in cores containing sea pens at stations characterized by predominantly bare sediments. Our results indicate that macrofaunal communities within sea pen fields differ from those in bare sediments and we propose sea pens play a role in influencing those patterns by increasing food availability, stability, and small-scale heterogeneity in sedimentary habitats, acknowledging that other environmental factors might also play a role in determining the observed patterns. Characteristics of macrofaunal communities within sea pen fields also suggested potentially higher sensitivity to disturbance, which amplifies the need for protection of sea pen fields in deep-sea sedimentary environments. [ABSTRACT FROM AUTHOR]

Rhodolith beds represent a key habitat worldwide, from tropical to polar ecosystems. Despite this habitat is considered a hotspot of biodiversity, providing a suite of ecosystem goods and services, still scarce quantitative information is available thus far about rhodolith beds occurrence and ecological role, especially in the Mediterranean Sea. This study reports the composition and patterns of distribution of rhodolith assemblages found in four study areas along ca. 860 km of coast in the Central Mediterranean Sea. These rhodolith beds were studied for the first time and significant differences at all spatial scales have been highlighted, documenting the high variability of this habitat. Rhodolith species composition, morphology and distribution have been discussed considering the potential role of environmental factors in driving these patterns. The need for improving their protection is discussed to complement present conservation and management initiatives, particularly in the frame of the EU Marine Strategy Framework Directive. [ABSTRACT FROM AUTHOR]

Rhodolith beds (RBs) are bioconstructions characterized by coralline algae, which provide habitat for several associated species. Mediterranean RBs are usually located in the mesophotic zone (below 40 m), and thus are frequently remote and unexplored. Recently, the importance and vulnerability of these habitats have been recognized by the European Community and more attention has been drawn to their investigation and conservation. This study reports the results of an extensive monitoring program, carried out within the Marine Strategy Framework Directive (2008/56/EC), in six sites off the Campania coast (Italy, Mediterranean Sea). New insights were given into the distribution, cover, vitality (i.e., live/dead rhodolith ratio), structural complexity, and coralline algae composition of RBs. Remotely operated vehicles (ROV) investigations allowed the description of several RBs, and the discovery of a RB with rhodolith cover >65% offshore the Capri Island. Only two sites (Secchitiello and Punta Campanella) showed a very low mean cover of live rhodoliths (<10%); hence, not being classifiable as RBs. The collected rhodoliths were mostly small pralines (~2 cm), spheroidal to ellipsoidal, with growth-forms ranging from encrusting/warty to fruticose/lumpy. Coralline algae identification revealed a high diversity within each bed, with a total of 13 identified taxa. The genus Lithothamnion dominated all sites, and Phymatolithon calcareum and Lithothamnion corallioides, protected by the Habitats Directive (92/43/EEC), were detected in all RBs. [ABSTRACT FROM AUTHOR]