Joana R. Xavier

• PhD
• Researcher at CIIMAR - Interdisciplinary Centre of Marine and Environmental Research

Seamounts are among the most common physiographic systems in the global deep ocean, defining habitat for a hugely diverse biome. Great Meteor Seamount is located in the subtropical Northeast Atlantic and is considered one of the largest seamounts worldwide. Despite its remoteness, it remains one of the few seamounts globally with a long research hi...

Sponges are key ecosystem engineers that shape, structure and enhance the biodiversity of marine benthic communities globally. Sponge aggregations and reefs are recognized as vulnerable marine ecosystems (or VMEs) due to their susceptibility to damage from bottom-contact fishing gears. Ensuring their long-term sustainability, preservation, and ecos...

The mesophotic zone represents one of our planet’s largest and least explored biomes. An increasing number of studies evidence the importance of macrofouling species in marine ecosystems, but information on these communities and the factors influencing their structures at mesophotic depths remain poor. This lack of understanding limits our ability...

Interest in the deep Arctic Ocean is rapidly increasing from governments, policy makers, industry, researchers, and conservation groups, accentuated by the growing accessibility of this remote region by surface vessel traffic. In this review, our goal is to provide an updated taxonomic inventory of benthic taxa known to occur in the deep Arctic Oce...

Seamounts are thought to function as hotspots of megafauna diversity due to their topology and environmental characteristics. However, assessments of megafauna communities inhabiting seamounts, including diversity and density, are scarce. In this study, we provide megafauna diversity and density estimates for a recently discovered, not yet characte...

Life in the deep ocean (200 meters or more below the surface) plays a central role in the marine carbon cycle by fixing, transferring, storing, and sequestering carbon from surface waters, forming the largest carbon reservoir on the planet. These processes have allowed the ocean to absorb 90% of excess heat and 25% of CO2 released into the atmosphe...

Management of deep-sea fisheries in areas beyond national jurisdiction by Regional Fisheries Management Organizations/Arrangements (RFMO/As) requires identification of areas with Vulnerable Marine Ecosystems (VMEs). Currently, fisheries data, including trawl and longline bycatch data, are used by many RFMO/As to inform the identification of VMEs. H...

Trait-based approaches that complement taxonomy-based studies have increased in popularity among the scientific community over the last decades. The collection of biological and ecological characteristics of species (i.e., traits) provides insight into species and ecosystem vulnerability to environmental and anthropogenic changes, as well as ecosys...

The deep-sea is vast, remote, and largely underexplored. However, methodological advances in environmental DNA (eDNA) surveys could aid in the exploration efforts, such as using sponges as natural eDNA filters for studying fish biodiversity. In this study, we analyzed the eDNA from 116 sponge tissue samples and compared these to 18 water eDNA sampl...

Little is known about dispersal in deep-sea ecosystems, especially for sponges, which are abundant ecosystem engineers. Understanding patterns of gene flow in deep-sea sponges is essential, especially in areas where rising pressure from anthropogenic activities makes difficult to combine management and conservation. Here, we combined population gen...

Industrial deep-sea mining will release plumes containing metals that may disperse over long distances; however, there is no general understanding of metal effects on marine ecosystems. Thus, we conducted a systematic review in search of models of metal effects on aquatic biota with the future perspective to support Environmental Risk Assessment (E...

Sponge-dominated habitats known as sponge grounds, aggregations, gardens and reefs are widely distributed in the world’s oceans. They are particularly prevalent in the upper bathyal zone along continental shelves and slopes (within EEZs), but are also found on oceanic ridges and seamounts in areas beyond national jurisdiction (ABNJs). These habita...

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Our understanding of the benthic communities on arctic seamounts and descriptions of such communities in habitat classification systems are limited. In recent years, Schulz Bank (73°52′N 7°30′E), a seamount on the Arctic Mid-Ocean Ridge (AMOR), has become well studied but the work has primarily focused on an arctic sponge ground at the summit. This...

In the deep ocean symbioses between microbes and invertebrates are emerging as key drivers of ecosystem health and services. We present a large-scale analysis of microbial diversity in deep-sea sponges (Porifera) from scales of sponge individuals to ocean basins, covering 52 locations, 1077 host individuals translating into 169 sponge species (incl...

The main aim of WKVMEBM 2022 was to develop and document an operational evidence-based procedure for the production of recurrent ICES advice on VMEs.

The Ægir Ridge System (ARS) is an ancient extinct spreading axis in the Nordic seas extending from the upper slope east of Iceland (∼550 m depth), as part of its Exclusive Economic Zone (EEZ), to a depth of ∼3,800 m in the Norwegian basin. Geomorphologically a rift valley, the ARS has a canyon-like structure that may promote increased diversity and...

Little is known about dispersal in deep-sea sponges, yet understanding patterns of gene flow and connectivity is essential for their effective management. Given rising pressure from harmful anthropogenic activities, schemes that manage resource extraction whilst conserving species diversity are increasingly necessary. Here, we used ddRADseq derived...

METEOR Cruise M150 BIODIAZ provided material from sublittoral down to deep-sea stations to incorporate innovative aspects into the study of seamount and island productivity and their potential role for the establishment of benthic assemblages comprising all size classes (George et al. 2021). The aim was to get a baseline on the diversity, faunal co...

The joint ICES/NAFO Working Group on Deep-water Ecology (WGDEC) collates new information on the distribution of Vulnerable Marine Ecosystems (VMEs) for use in annual ICES advisory processes and the development of new methods/techniques to further our understanding of deep-sea ecosystems, and further suggests novel management tools to ensure human a...

Sponges are amongst the most diffi cult benthic taxa to properly identify, which has led to a prevalence of cryptic species in several sponge genera, especially in those with simple skeletons. This is particularly true for sponges living in remote or hardly accessible environments, such as the deep-sea, as the inaccessibility of their habitat and th...

Vulnerable marine ecosystems (VMEs) are particularly susceptible to bottom-fishing activity as they are easily disturbed and slow to recover. A data-driven approach was developed to provide management options for the protection of VMEs under the European Union “deep-sea access regulations.” A total of two options within two scenarios were developed...

Deep-sea North Atlantic sponge grounds are crucial components of the marine fauna providing a key role in ecosystem functioning. To properly develop effective conservation and management plans, it is crucial to understand the genetic diversity, molecular connectivity patterns and turnover at the population level of the species involved. Here we pre...

Lithistid sponges are globally distributed in temperate and sub-tropical areas, constituting an important component of deep-sea benthic communities where they form structurally complex and vulnerable marine ecosystems (VMEs). In this study, we assess the diversity and investigate the spatial and bathymetric distribution of the lithistid sponges of...

Demosponges are a well-known source of a plethora of bioactive compounds. In particular, they are able to form a skeleton by direct deposition of silica in a process catalyzed by silicatein. Herein, we isolated biosilicas from five different Atlantic deep-sea sponges Geodia atlantica (GA), Geodia barretti (GB), Stelletta normani (SN), Axinella infu...

The available data on trace elements (TE) of deep-sea organisms is scarce and nonexistent for rare earth elements (REE). Hence, this study characterizes REE and TE in five porifera genera (Jaspis, Geodia, Hamacantha, Leiodermatium, Poliopogon) collected in deep-sea areas (between 481 and 2656 m) of the North Atlantic. Aluminium was the most common...

Sponges occur ubiquitously in the marine realm and in some deep-sea areas they dominate the benthic communities forming complex biogenic habitats – sponge grounds, aggregations, gardens and reefs. However, deep-sea sponges and sponge-grounds are still poorly investigated with regards to biotechnological potential in support of a Blue growth strateg...

Under regulation (EU) 2016/2336, the EU fleet will be banned from bottom fishing in all waters between 400 and 800m in depth, apart from within the existing fishing footprint. Within the fishing footprint, EU vessels will be prohibited from bottom fishing in any closed areas that might be introduced to protect VMEs. To meet these regulatory require...

The United Nations Decade of Ocean Science for Sustainable Development presents an exceptional opportunity to effect positive change in ocean use. We outline what is required of the deep-sea research community to achieve these ambitious objectives.

The ocean plays a crucial role in the functioning of the Earth System and in the provision of vital goods and services. The United Nations (UN) declared 2021–2030 as the UN Decade of Ocean Science for Sustainable Development. The Roadmap for the Ocean Decade aims to achieve six critical societal outcomes (SOs) by 2030, through the pursuit of four o...

The workshop aimed to identify coherent, collaborative, and scientifically robust solutions to addressing taxonomic knowledge gaps in various stages from collection, preservation and archiving of biological samples and taxonomic data to identification and description of species. Specifically, the workshop focused on: (i) identifying specific needs...

Deep-sea sponge-dominated communities are complex habitats considered hotspots of biodiversity and ecosystem functioning. They are classified as Vulnerable Marine Ecosystem and are listed as threatened or declining as a result of anthropogenic activities. Yet, studies into the distribution, community structure and composition of these habitats are...

Background Lithistid demosponges, also known as rock sponges, are a polyphyletic group of sponges which are widely distributed. In the Northeast Atlantic (NEA), 17 species are known and the current knowledge on their distribution is mainly restricted to the Macaronesian islands. In the Mediterranean Sea, 14 species are recorded and generally found...

Sponges are commonly known as general nutrient providers for the marine ecosystem, recycling organic matter into various forms of bioavailable nutrients such as ammonium and nitrate. In this study we challenge this view. We show that nutrient removal through microbial denitrification is a common feature in six cold-water sponge species from boreal...

Video and image data are regularly used in the field of benthic ecology to document biodiversity. However, their use is subject to a number of challenges, principally the identification of taxa within the images without associated physical specimens. The challenge of applying traditional taxonomic keys to the identification of fauna from images has...

Background Knowledge about the distribution of the genetic variation of marine species is fundamental to address species conservation and management strategies, especially in scenarios with mass mortalities. In the Mediterranean Sea, Petrosia ficiformis is one of the species most affected by temperature-related diseases. Our study aimed to assess i...

This identification guide has been developed to support the monitoring of bycatch of vulnerable species in Mediterranean fisheries. The work has been produced within the context of the project “Understanding Mediterranean multi-taxa ‘bycatch’ of vulnerable species and testing mitigation– a collaborative approach” funded by MAVA Foundation through a...

A recent phylogenetic study revealed a close relationship between chiactine-bearing (family Achramorphidae, order Leucosolenida) and pugiole-bearing (order Baerida) calcaronean sponges as well as new putative taxa within Achramorphidae. In this study, we present a revision of chiactine-bearing sponges based on morphological re-examination of type m...

The joint ICES/NAFO Working Group on Deep-water Ecology (WGDEC) collates new information on the distribution of Vulnerable Marine Ecosystems (VMEs) for use in annual ICES advisory processes and the development of new methods/techniques to further our understanding of deep-sea ecosystems, and further suggests novel management tools to ensure human a...

Ferromanganese crusts occurring on seamounts are a potential resource for rare earth elements that are critical for low-carbon technologies. Seamounts, however, host vulnerable marine ecosystems (VMEs), which means that spatial management is needed to address potential conflicts between mineral extraction and the conservation of deep-sea biodiversi...

Sponges are commonly known as general nutrient providers for the marine ecosystem, recycling organic matter into various forms of bio-available nutrients such as ammonium and nitrate. In this study we challenge this view. We show that nutrient removal through microbial denitrification is a common feature in six cold-water sponge species from boreal...

Emerald Basin on the Scotian Shelf off Nova Scotia, Canada, is home to a globally unique population of the glass sponge Vazella pourtalesi. Through the analysis of both in situ photo graphs and trawl catch data from annual multispecies bottom-trawl surveys, we examined community composition, species density, and abundance of epibenthos and fish ass...

Deep-sea sponge-dominated communities are complex habitats considered hotspots of biodiversity and ecosystem functioning. They are classified as Vulnerable Marine Ecosystem and are listed as threatened or declining as a result of anthropogenic activities. Yet, studies into the distribution, community structure and composition of these habitats are...

The silicon isotopic composition (δ30Si) of deep sea sponges' skeletal element – spicules – reflects the silicic acid (DSi) concentration of their surrounding water and can be used as natural archives of bottom water nutrients. In order to reconstruct the past silica cycle robustly, it is essential to better constrain the mechanisms of biosilicific...

Deep Reef Benthos of Bermuda builds on the video and imagery data collected during Nekton’s Mission – the XL Catlin Deep Ocean Survey - and provides a photographic guide for the visual identification of many of the corals, marine plants and other common invertebrates that inhabit Bermuda’s outer deep reefs. This guide is designed to aid marine bio...

Emerald Basin on the Scotian Shelf off Nova Scotia, Canada, is home to a globally unique aggregation of the glass sponge Vazella pourtalesi, first documented in the region in 1889. In 2009, Fisheries and Oceans Canada (DFO) implemented two Sponge Conservation Areas to protect these sponge grounds from bottom fishing activities. Together, the two co...

Presence and absence response data of V. pourtalesi collected between 1997 and 2017. Data source are DFO's multispecies trawl survey, DFO optical surveys, and commercial catch data from the Fisheries Observer Program (FOP). Note that records from the FOP program do not have a unique trip identifier. (XLSX)

Predicted presence probability of V. pourtalesi from a random forest model built on V. pourtalesi presence-absence data, and areas of model extrapolation (i.e., those areas where the environmental data are outside the bounds of those used to train the model) indicated by the grey polygon. Also shown are the presence-absence data used to train the m...

Correlation matrix based on Spearman’s rank correlation coefficient (ρ) between all 63 environmental predictor variables considered for random forest modelling. Circle size indicates the magnitude of the correlation (large circles = highly correlation; small circles indicate lower correlation), and colour indicates direction (blue = positive; red =...

Sponge-dominated communities are increasingly recognized as key functional ecosystems of the deep-sea. In the past decades various of such ecosystems have been discovered in the North Atlantic, most of which dominated by species of Geodia, Stryphnus, Stelletta, Thenea and Phakellia and/or Hexactinellida. Here we report a multispecific aggregation d...

Caminella Lendenfeld, 1894 is a poorly known Geodiidae genus with unclear phylogenetic relationships. In order to find new lines of evidence that could shed light on the evolutionary history of Caminella, we decided to revise type material and museum material, as well as examine new material from underwater caves and deep-sea ecosystems. In doing s...

The silicon isotope composition of deep-sea sponges skeletal element – spicules – reflects the silicic acid (DSi) concentration of their surrounding water, and can be used as natural archives of bottom water nutrients. In order to reconstruct the past silica cycle robustly, it is essential to better constrain the mechanisms of biosilicification, wh...

Calcaronean sponges are acknowledged to be taxonomically difficult, and generally, molecular data does not support the current morphology-based classification. In addition, molecular markers that have been successfully employed in other sponge taxa (e.g., COI mtDNA) have proven challenging to amplify due to the characteristics of calcarean mitochon...

Current knowledge of sponge microbiome functioning derives mostly from comparative analyses with bacterioplankton communities. We employed a metagenomics-centered approach to unveil the distinct features of the Spongia officinalis endosymbiotic consortium in the context of its two primary environmental vicinities. Microbial metagenomic DNA samples...

This poster includes a selection of important deep-sea sponge taxa known to occur in the Mediterranean Sea. Each taxon is described using on-deck, laboratory or underwater photos, and information on their morphology, characteristics, texture, important identification characters, colour, size and depth of occurrence are also provided. A section on s...

Among marine organisms, sponges are the richest sources of pharmacologically-active compounds. Stemming from a previous lead discovery program that gathered a comprehensive library of organic extracts of marine sponges from the off-shore region of Portugal, crude extracts of Erylus cf. deficiens collected in the Gorringe Bank (Atlantic Ocean) were...

The family Cladorhizidae (Porifera) comprises a particularly interesting group of sponges that has developed a carnivorous feeding strategy unique within the phylum. Cladorhizids are typically considered deep-sea sponges, are frequently found at oceanic ridges and seamount systems, and new species are continuously discovered as new areas are explor...

Sponges are a key component of the deep-sea benthos, where they form structurally complex habitats and provide numerous ecosystem goods and services. However, there is still an enormous knowledge gap regarding the diversity, distribution and systematics of this group. This special volume presents the results of the 1st International Workshop on Tax...

Due to anthropogenic disturbances, the common sponge Petrosia ficiformis has suffered from severe disease outbreaks coincidental with episodic raises in seawater temperature. Here, we report on the optimization of 10 microsatellites that can be used to estimate population connectivity and structure. This information will be critical for further con...

The subfamilies Acastinae and Bryozobiinae and the genus Membranobalanus are three groups of barnacles (Cirripedia: Archaeobalanidae) with species known to be obligate symbionts of Porifera. Few studies have attempted to identify both sponge and barnacle taxa in these relationships. Even less is known regarding the species-level specificity of the...