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.
The Phoenix Islands Protected Area, in the central Pacific waters of the Republic of Kiribati, is a model for large marine protected area (MPA) development and maintenance, but baseline records of the protected biodiversity in its largest environment, the deep sea (>200 m), have not yet been determined. In general, the equatorial central Pacific lacks biogeographic perspective on deep-sea benthic communities compared to more well-studied regions of the North and South Pacific Ocean. In 2017, explorations by the NOAA ship Okeanos Explorer and R/V Falkor were among the first to document the diversity and distribution of deep-water benthic megafauna on numerous seamounts, islands, shallow coral reef banks, and atolls in the region. Here, we present baseline deep-sea coral species distribution and community assembly patterns within the Scleractinia, Octocorallia, Antipatharia, and Zoantharia with respect to different seafloor features and abiotic environmental variables across bathyal depths (200–2500 m). Remotely operated vehicle (ROV) transects were performed on 17 features throughout the Phoenix Islands and Tokelau Ridge Seamounts resulting in the observation of 12,828 deep-water corals and 167 identifiable morphospecies. Anthozoan assemblages were largely octocoral-dominated consisting of 78% of all observations with seamounts having a greater number of observed morphospecies compared to other feature types. Overlying water masses were observed to have significant effects on community assembly across bathyal depths. Revised species inventories further suggest that the protected area it is an area of biogeographic overlap for Pacific deep-water corals, containing species observed across bathyal provinces in the North Pacific, Southwest Pacific, and Western Pacific. These results underscore significant geographic and environmental complexity associated with deep-sea coral communities that remain in under-characterized in the equatorial central Pacific, but also highlight the additional efforts that need to be brought forth to effectively establish baseline ecological metrics in data deficient bathyal provinces.
The integrated study of ocean health and human health is an emerging area of increasing global importance. Growing evidences demonstrate that the health of the ocean and the health of humans have always been and will continue to be, inextricably linked. Our actions toward the oceans will significantly influence the future of the whole planet and, in turn, our own health. The current review of these issues arose from a summer school in San Sebastian (Spain), from 5th to 7th June, 2019. An interdisciplinary group of researchers discussed key risks (e.g., microbial pollution, pharmaceuticals, harmful algal blooms, plastic pollution) and benefits (e.g., bathing waters, recreation, tourism) of the seas and global ocean for humanity; and debated the future priorities and potential actions for a joint Oceans and Human Health research and governance programme in Europe. The aim of this review is to contribute to the emerging scientific agenda on ocean health and human health, as well as coordinate efforts with stakeholders, policy makers and the general public. This agenda operates within the larger context of the upcoming United Nations Decade of Ocean Science for Sustainable Development: 2021–2030, which strives to achieve the Sustainable Development Goals (SDG), including healthy (human) lives and well-being (SDG3) and conserving and sustainably using the oceans (SDG14), among others. In addition to summarizing some of the key risks and benefits, therefore, we describe the governance of oceans and health interactions (especially in Europe), and we finish by proposing a list of elements for potential future research priorities on oceans and human health.
On 1 March 2019, the United Nations (UN) General Assembly (New York) declared 2021–2030 the “UN Decade on Ecosystem Restoration.” This call to action has the purpose of recognizing the need to massively accelerate global restoration of degraded ecosystems, to fight the climate heating crisis, enhance food security, provide clean water and protect biodiversity on the planet. The scale of restoration will be key; for example, the Bonn Challenge has the goal to restore 350 million km2 (almost the size of India) of degraded terrestrial ecosystems by 2030. However, international support for restoration of “blue” coastal ecosystems, which provide an impressive array of benefits to people, has lagged. Only the Global Mangrove Alliance (https://mangrovealliance.org/) comes close to the Bonn Challenge, with the aim of increasing the global area of mangroves by 20% by 2030. However, mangrove scientists have reservations about this target, voicing concerns that it is unrealistic and may prompt inappropriate practices in attempting to reach this target (Lee et al., 2019). The decade of ecosystem restoration declaration also coincides with the UN Decade of Ocean Science for Sustainable Development, which aims to reverse deterioration in ocean health. If executed in a holistic and coordinated manner, signatory nations could stand to deliver on both these UN calls to action.
Growth of the blue bioeconomy has potential for contributing positively toward economic growth, societal needs and multiple United Nations Sustainable Development Goals. However, organizations currently experience many challenges which limit success in this field. The aim of this paper is to identify trends in challenges linked to target end markets, stages in the value chain and organization types, to suggest potential solutions and link these to potential novel business models. A survey was completed by 58 organizations representing countries across four continents, and interviews were conducted with seven selected European start-ups/SMEs, to gather information regarding existing bottlenecks and to validate their business model. Results indicate that organizations targeting the pharmaceutical and nutraceutical sector experience a majority of challenges related to supply and technology, whereas organizations targeting the industrial biotechnology or agricultural industry experience more issues linked to market. Both bottom-up and top-down approaches could be applied in order to implement suggested actions. Analysis of the business model canvas used by start-ups/SMEs revealed potential for improvement. In particular, it was noted that review of the ‘revenue stream’ segment within the business model, specifically regarding alternatives to governmental funding, could be helpful for the long-term survival of these types of organizations.
The mitigation hierarchy has been proposed as an overarching framework for managing fisheries and reducing marine megafauna bycatch, but requires empirical application to show its practical utility. Focusing on a small-scale fishing community in Peru as a case study system, we test how the mitigation hierarchy can support efforts to reduce captures of sea turtles in gillnets and link these actions to broader goals for biodiversity. We evaluate three management scenarios by drawing on ecological risk assessment (ERA) and qualitative management strategy evaluation to assess trade-offs between biological, economic, and social considerations. The turtle species of management focus include leatherback turtle Dermochelys coriacea, green turtle Chelonia mydas, and olive ridley turtle Lepidochelys olivacea. Adopting a mixed-methods iterative approach to data collection, we undertook a literature review to collate secondary data on the fishery and the species of turtles captured. We then collected primary data to fill the knowledge gaps identified, including establishing the spatial extent of the fishery and calculating turtle capture rates for the fishery. We identified and evaluated the potential risk that the fishery poses to each turtle species within Pacific East regional management units using a qualitative ERA. Finally, we evaluated potential management strategies to reduce turtle captures, incorporating stakeholder preference from questionnaire-based surveys and considering preliminary estimates of trends across a range of performance indicators. We illustrate how the proposed framework can integrate existing knowledge on an issue of marine megafauna captures, and incorporate established decision-making processes to help identify data gaps. This supports a holistic assessment of management strategies toward biodiversity goals standardized across fisheries and scales.
The Mediterranean Sea is classified as a “data-poor” region in fisheries due to its low number of assessed stocks given its biodiversity and number of exploited species. In this study, the CMSY method was applied to assess the status and exploitation levels of 54 commercial fish and invertebrate stocks belonging to 34 species fished by Turkish fleets in the Eastern Mediterranean (Levantine) and Black Seas, by using catch data and resilience indices. Most of these marine taxa currently lack formal stock assessments. The CMSY method uses a surplus production model (SPM), based on official catch statistics and an abundance index derived from scientific surveys. The SPM estimates maximum sustainable yield (MSY), fishing mortality (F), biomass (B), fishing mortality to achieve sustainable catches (Fmsy), and the biomass to support sustainable catches (Bmsy). Our results show the estimated biomass values for 94% of the stocks were lower than the required amount to support sustainable fisheries (Bmsy). Of the 54 stocks, 85% of them can be deemed as overfished; two stocks were not subject to overfishing (Sardina pilchardus and Trachurus mediterraneus in the Marmara Sea) while only one stock (Sprattus sprattus in the Black Sea) is healthy and capable of producing MSY. Annual values of the stock status indicators, F/Fmsy and B/Bmsy, had opposing trends in all regions, suggesting higher stock biomasses could only be achieved if fishing mortality is drastically reduced. Recovery times and levels were then explored under four varying F/Fmsy scenarios. Under the best-case scenario (i.e., F = 0.5Fmsy), over 60% of the stocks could be rebuilt by 2032. By contrast, if normal fishing practices continue as usual, all stocks will soon be depleted [if not already] (F = 0.95Fmsy), whose recover may be impossible at later dates. The results of this study are supported by previous regional assessments confirming the overexploitation of Turkish fisheries is driving the near-total collapse of these marine wild fisheries. Hence, the need to urgently rebuild Turkey’s marine fisheries ought to be prioritized to ensure their future viability.
Jellyfish are important components of marine food webs and form problematic blooms that negatively impact human enterprise. Jellyfish of the genus Aurelia (Class Scyphozoa) are common bloom-formers in the Gulf of Mexico (GoM). Aurelia have a multi-modal life cycle where the perennial polyp produces seasonal medusae. Abiotic tolerance ranges and limits strongly influence the distribution of marine species but are unknown for most jellyfish species. Tolerance limits for survival are crucial to understanding present polyp distribution and how distribution may change in climate change scenarios. We sampled and barcoded two Aurelia species from the GoM, namely Aurelia sp. 9 and a possible new species found offshore (Aureliasp. new). Planulae obtained from one medusa of Aurelia sp. new, and five medusae of Aurelia sp. 9 were used to establish laboratory cultures. Polyps of Aurelia coerulea, a species native to Japan but introduced in North America, Australia, and Europe, were obtained from a local aquarium, barcoded, and used to establish laboratory cultures. Using controlled laboratory experiments, we determined the temperature and salinity limits for polyp survival of the two GoM species and A. coerulea. We find that A. sp. 9 and A. coerulea were tolerant of a broad range of temperatures and salinities, but differed in tolerance limits, suggesting potential differences in habitat and resistance to climate change. A. sp. 9 was most tolerant of high temperatures and low salinities, such as those found in the estuaries of the GoM. Summer high temperatures in the coastal GoM exceed the upper thermal tolerance limit of A. sp. new and A. coerulea, suggesting that A. sp. new is an offshore species and that the coastal GoM waters may not be a suitable environment for A. coerulea. Based on the upper thermal limits identified in this study, the 4°C ocean temperature increase projected for the GoM by the next century may negatively impact Aurelia sp. 9 and Aurelia sp. new populations and is expected to deter A. coerulea from invading the GoM. This is the first account of Aurelia sp. new and the first report of temperature and salinity ranges and tolerance limits for Aurelia species.
Spatial claims concerning the rapidly growing European offshore wind sector give rise to various ideas for the multi-use application of wind farms. Seaweed is considered a promising feedstock for food and feed that could be produced at offshore wind farms. Concerns about risks resulting in liability claims and insurance premiums are often seen as show-stoppers to multi-use at offshore wind farms. In this study, key environmental risks of seaweed cultivation at offshore wind farms, identified through literature review, are characterized based on stakeholder consultation. The current approach to risk governance is evaluated to assess how it can handle the uncertain, complex, and/or ambiguous risks of multi-use. It is concluded that current risk governance for multi-use is poorly equipped to deal with the systemic nature of risks. Risk governance should be a joint effort of governments and private regulators. It can improve if it is based on an adaptive framework for risk assessment that can deal with complex, systemic risks. Furthermore, it should be flexible and inclusive, i.e., open to new incoming information and stakeholder input, and taking into account and communicate about the different stakes and values of the various parties involved. The importance of communication and inclusion must be recognized, which promotes participation of concerned stakeholders.
Vessel traffic management systems can be employed for environmental management where vessel activity may be of concern. One such location is in San Francisco Bay where a variety of vessel types transit a highly developed urban estuary. We analyzed vessel presence and speed across space and time using vessel data from the Marine Monitor, a vessel tracking system that integrates data from the Automatic Identification System and a marine-radar sensor linked to a high-definition camera. In doing so, we provide data that can inform collision risk to cetaceans who show an increased presence in the Bay and evaluation of the value in incorporating data from multiple sources when observing vessel traffic. We found that ferries traveled the greatest distance of any vessel type. Ferries and other commercial vessels (e.g., cargo and tanker ships and tug boats) traveled consistently in distinct paths while recreational traffic (e.g., motorized recreational craft and sailing vessels) was more dispersed. Large shipping vessels often traveled at speeds greater than 10 kn when transiting the study area, and ferries traveled at speeds greater than 30 kn. We found that distance traveled and speed varied by season for tugs, motorized recreational and sailing vessels. Distance traveled varied across day and night for cargo ships, tugs, and ferries while speed varied between day and night only for ferries. Between weekdays and weekends, distance traveled varied for cargo ships, ferries, and sailing vessels, while speed varied for ferries, motorized recreational craft, and sailing vessels. Radar-detected vessel traffic accounted for 33.9% of the total track distance observed, highlighting the need to include data from multiple vessel tracking systems to fully assess and manage vessel traffic in a densely populated urban estuary.
The Firth of Clyde, on the west coast of Scotland, was once one of the most productive fishing grounds in Europe. However, successive decades of poor management and overfishing led to a dramatic loss of biodiversity and the collapse of finfish fisheries. In response, concerned local residents on the Isle of Arran, which lies in the middle of the Clyde, formed the Community of Arran Seabed Trust (COAST) in 1995. After 13 years of campaigning, a small (2.67 km2) area in Lamlash Bay became Scotland’s first no-take zone (NTZ) in 2008, and only the second in the UK. Since protection, biodiversity has increased substantially, along with the size, age and density of commercially important species such as the king scallop, Pecten maximus, and the European lobster, Homarus gammarus. Arguably more important, however, is the influence the Lamlash Bay NTZ and COAST have had on UK marine protection in general. Most notably, detailed research has created a case study that clearly demonstrates the benefits of protection in an area where little such evidence is available. This case has been used repeatedly to support efforts for increased protection of UK waters to help rebuild marine ecosystems and enhance their resilience in an uncertain future. In Scotland specifically, lobbying by COAST led to the designation of a much larger marine protected area (MPA, >250 km2) around the south of Arran, one of 30 new MPAs in the country. Evidence from Lamlash Bay has supported development of strong protection for these MPAs, seeing off lobbyist efforts to weaken management. Arran’s conservation success has been recognized internationally and is inspiring greater involvement of local communities around the UK, and further afield, to take the destiny of their coastal waters into their own hands. Successful marine conservation begins at home.
Reducing the impact on vulnerable species through changes in fishing practices, such as the spatial or temporal avoidance of certain areas, is key to increase the ecological sustainability of fisheries. However, it is often hampered by the availability of sufficiently detailed data and robust indicators. Existing trawl surveys are a cost-effective data source to assess the vulnerability of fishing areas based on the quantities of vulnerable species caught. We developed a biological traits-based approach to the vulnerability of demersal assemblages using commercial trawl catch data. An expert-based approach identified a set of biological traits that are expected to condition the species’ response to trawling impact and are combined to produce the vulnerability index ranked into four levels (low, moderate, high, and very high vulnerability). The approach was tested in four southern European fishing grounds showing evidence of over-exploitation, through catches being dominated by species of relatively low vulnerability to fishing impacts. The general distribution of species’ biomass amongst vulnerability groups was highly homogenous across case studies, despite local differences in fishing fleet structure, target species and fishing depths. Within all areas the species with moderate vulnerability dominated and, in most instances, species of “very high” vulnerability were not recorded. Nevertheless, differences emerged when comparing the proportions of highly vulnerable species in the catches. Variability in vulnerability level of the catch was also observed at small spatial scales, which was principally explained by differences in habitat type and depth and, secondarily, by fishing effort. In fine mud in the shallower areas there was a higher presence of low vulnerable fauna. Furthermore, vulnerable organisms decreased in their presence in sandier substrates on the continental shelf. The spatial heterogeneity in assemblage vulnerability composition encourages the potential for adoption of this index in the spatial management of fishing grounds aiming at ensuring a sustainable exploitation by mitigating trawl impacts on the most vulnerable components of the demersal assemblages.
In order to understand the multiple values of landscape, this paper suggests an evaluative methodology that takes into account a quantitative approach, public opinion, and an economic estimation. This study analyzes the coastal scenery of 40 Italian beaches using a fuzzy logic and a Contingent Valuation (CV). Each site was classified into five categories: Class I beaches were littorals with high natural settings; Class II sites were natural and semiurban beaches having low influences by anthropic structures; Classes III, IV, and V had lower evaluations due to poor physical and human condition. A questionnaire survey analyzed beach users’ preferences, judgment, and Willingness to Pay (WTP). Results suggest that landscape judgment is directly correlated to scenery assessment; therefore, beaches of Class I and II were judged beautiful while beaches of Class IV and V had poor judgments. Similarly, the importance given to the landscape was highest in Class I and II than in the others. WTP for the conservation of the selected beaches was about €16 per season. Our findings suggest that people are disposed to pay more for a beach with the top-grade of scenery (Class I and II) and low grade of urbanization. Moreover, WTP would rise for females and for nonresident users with an academic degree, which appreciated the coastal landscape.
Biodiversity loss and climate change simultaneously threaten marine ecosystems, yet their interactions remain largely unknown. Ocean acidification severely affects a wide variety of marine organisms and recent studies have predicted major impacts at the pH conditions expected for 2100. However, despite the renowned interdependence between biodiversity and ecosystem functioning, the hypothesis that the species’ response to ocean acidification could differ based on the biodiversity of the natural multispecies assemblages in which they live remains untested. Here, using experimentally controlled conditions, we investigated the impact of acidification on key habitat-forming organisms (including corals, sponges and macroalgae) and associated microbes in hard-bottom assemblages characterised by different biodiversity levels. Our results indicate that, at higher biodiversity, the impact of acidification on otherwise highly vulnerable key organisms can be reduced by 50 to >90%, depending on the species. Here we show that such a positive effect of a higher biodiversity can be associated with higher availability of food resources and healthy microbe-host associations, overall increasing host resistance to acidification, while contrasting harmful outbreaks of opportunistic microbes. Given the climate change scenarios predicted for the future, we conclude that biodiversity conservation of hard-bottom ecosystems is fundamental also for mitigating the impacts of ocean acidification.
In response to the 2015 and 2017 decisions of the World Heritage Committee, the Australian government submitted to the World Heritage Centre in December 2019 the State Party Report on the state of conservation of the Great Barrier Reef (GBR) World Heritage Area (WHA). The 2017 decision of the World Heritage Committee (WHC) focussed on two areas in particular, namely:
4. .... accelerate efforts to ensure meeting the intermediate and long-term targets of the [Reef 2050 Long-Term Sustainability] plan ... in particular regarding water quality;
6. .... demonstrating the effective and sustained protection of the property’s Outstanding Universal Value and effective performance in meeting the targets established under the 2050 LTSP [Reef 2050 Long-Term Sustainability Plan], linked to the findings of the 2014 and 2019 Great Barrier Reef Outlook Reports.
This review also focusses on these two areas, as well as the implications of Australia’s current climate change polices and the existing funding arrangements for management of the GBR.
Relative to previous GBR State Party Reports (2013, 2014, 2015) the 2019 Report provides more detail on funding arrangements and progress to achieving management targets. Overall, it is a more informative document. However, it still overstates the efficacy of existing management arrangements and understates the critical importance of effectively and immediately addressing the causes of climate change. We are concerned particularly by the present Australian government’s inadequate national climate change and energy policies and programs, and the implications these have for the future of the Great Barrier Reef.
The ingestion of microplastics has been recorded in hundreds of species. The ingestion rate and degree of impact is species-specific and depends on food preferences, foraging behaviour, and plastic pollution of the area. Currently there is a large knowledge gap regarding ingestion of marine litter by invertebrates in brackish water bodies. Therefore, experiments were conducted to investigate microplastics uptake and potential accumulation in the digestive system of the Harris mud crab Rhithropanopeus harrisii. Effects of microplastics on the growth of crabs were also tested. The results show that R. harrisii consume microplastics together with food, only plastic fragments too large for the digestion system were removed by crabs. The effect and duration of passage of plastic are not consistent and depend on the size and type of plastic. Microplastic fragments (<0.25 mm) ingested by crab were continuously egested while knotted fibres may accumulate in the stomach. The crabs fed with plastic supplements lost weight or had lower weight increase compared to control group after two-month treatment. However, the differences between treatments were not statistically significant. For the first time, occurrence of plastic in the digestive system of crabs collected from the natural habitats of Pärnu Bay (NE Baltic Sea, Estonia) was studied. Among all the crabs examined, 5% of specimens were found with fibres in their stomach assimilated prior to their capture from nature.
Historical coral skeleton (CS) δ18O and δ15N records were produced from samples recovered from sedimentary deposits, held in natural history museum collections, and cored into modern coral heads. These records were used to assess the influence of global warming and regional eutrophication, respectively, on the decline of coastal coral communities following the development of the Pearl River Delta (PRD) megacity, China. We find that, until 2007, ocean warming was not a major threat to coral communities in the Pearl River estuary; instead, nitrogen (N) inputs dominated impacts. The high but stable CS‐δ15N values (9‰–12‰ vs. air) observed from the mid‐Holocene until 1980 indicate that soil and stream denitrification reduced and modulated the hydrologic inputs of N, blunting the rise in coastal N sources during the early phase of the Pearl River estuary urbanization. However, an unprecedented CS‐δ15N peak was observed from 1987 to 1993 (>13‰ vs. air), concomitant to an increase of NH4+ concentration, consistent with the rapid Pearl River estuary urbanization as the main cause for this eutrophication event. We suggest that widespread discharge of domestic sewage entered directly into the estuary, preventing removal by natural denitrification hotspots. We argue that this event caused the dramatic decline of the Pearl River estuary coral communities reported from 1980 to 2000. Subsequently, the coral record shows that the implementation of improved wastewater management policies succeeded in bringing down both CS‐δ15N and NH4+ concentrations in the early 2000s. This study points to the potential importance of eutrophication over ocean warming in coral decline along urbanized coastlines and in particular in the vicinity of megacities.
WWF and CoNISMa outline an adaptive methodology for evaluating key economic benefits, potentially applicable in different Mediterranean Marine Protected Areas (MPAs). The study was piloted in 6 MPAs: 3 MPAs with an official mission and long-term management plans – Egadi Islands MPA (Italy), Telašćica Nature Park (Croatia), Torre Guaceto MPA (Italy) – and 3 not-yet officially gazetted MPA without an operational management plan – Gouraya National Park, Taza National Park in Algeria and Tabarka Marine and Coastal Protected Area in Tunisia.
Seabed litter of the Flemish Pass area (NW Atlantic Ocean) was analysed and described using data from the EU-Spain groundfish survey (2006-2017 period). This study presents baseline information on seabed litter in this area. The Flemish Pass is located in areas beyond national jurisdiction within the Northwest Atlantic Fisheries Organization Regulatory Area Division 3L. A total of 1169 valid bottom trawl hauls were analysed (104-1478 m depth). Litter was found in 8.3% of the hauls, with mean densities of 1.4±0.2 items km–2 and 10.6±5.2 kg km–2. An increasing pattern with depth was found, the highest densities of seabed litter being identified in the deepest areas located in the Flemish Pass channel and down the northeastern flank of the Grand Bank. Fishing was found to be the main source of marine litter, and 61.9% of the hauls with litter presence showed litter included in the fisheries-related litter category. Whereas in most cases the litter was composed of small fragments of rope, in other cases it was composed of entire fishing gears such as traps. Plastics, metal and other anthropogenic litter were the next most abundant categories, accounting for 18.6%, 16.5% and 12.4% of the total, respectively.
Marine ecosystems are directly threatened by multiple and interactive human stressors at global and local scales. Hence, it is vital to study biodiversity and ecological patterns through a multi-disciplinary approach, from understanding global diversity patterns to evaluating the ecological responses of species to different impacts in order to protect marine ecosystems. Until this moment most of related ecological studies have focused on charismatic and popular groups, such as gorgonians, corals, macroalgae or seagrasses. In this thesis, we focused on bryozoans, an abundant group of sessile marine invertebrates distributed worldwide, but generally understudied. Moreover, large bryozoans are considered habitat-forming species that can create bioconstructions enhancing the associated biodiversity and providing different ecological benefits. Bearing this in mind, the main aim of this thesis was to provide different approaches to understand discovery and macroecological patterns at global scales, and the response of species to different stressors at local scales, combining the use of open databases, the in situ monitoring of natural populations, experiments in aquaria and the development of restoration techniques. Furthermore, the present thesis aims to contribute to provide a general framework to identify and protect vulnerable populations in the context of increasing human threats.
In the first chapter, the discovery patterns of fossil and extant bryozoans revealed the highest number of fossil species described, highlighting that the current biodiversity represents only a small proportion of Earth’s past biodiversity. Beyond these differences, both groups showed an increase in the taxonomic effort during the past century, reflecting the increase in the interest in the exploration of the marine environment, and the improvement of technological developments. Despite this progress, future projections of discovery patterns of both groups showed a large proportion of species remaining to be discovered by the end of this century, which corroborate the need to increase the effort to name and quantify marine biodiversity before hundreds of species become extinct due to human impacts.
In chapter 2, a comparative approach between marine sessile and bryozoan biodiversity patterns reported that the most of sessile groups presented higher diversity in the Southern ocean, displaying a non-unimodal latitudinal pattern with a dip in the number of species at the equator, contrary to the most traditionally accepted pattern in diversity studies. Moreover, this region will represent the less affected by global warming at the final of this century, suggesting that the high species richness recorded in this region may be explained by it has suffered lower temperature stress over evolutionary time. Related to biases in sampling effort, our analyses showed that the most sampled region for both marine sessile species and bryozoans was North Temperate Atlantic. To identify and quantify environmental drivers for both groups, we tested the effect of using the popular method of rarefaction to correct sampling effort biases vs the incorporation of a frequency index of sampling effort as co-variate in quantitative models. Despite we obtained the same best predictors for both approches (depth, nitrate, and SST), the models using the correction of sampling biases through frequency index showed better fitting, encouraging to incorporate this methodology in future studies.
Focusing on the Mediterranean Sea, in Chapter 3 we studied the responses of bryozoans to different stressors. First, we showed that two abundant and common bryozoans, Pentapora fascialis and Myriapora truncata, displayed different tolerances to warming. Through the combination of in situ monitoring and experiments in aquaria, we revealed that mass mortality event recorded of Pentapora fascialis populations during summer 2015 may be explained by its lower thermal tolerance ranks. Moreover, in Chapter 4 we take the advantage of the in situ monitoring of Pentapora fascialis natural populations increasing the spatial and temporal effort, revealing that the bryozoan Pentapora fascialis is characterized by fast population dynamics, with high recruitment and growth rates, and a high capacity of recovery. Accordingly, we observed an increase in the density of its populations in the Marine Reserve of Medes Island since the 1990s. However, we evidenced that in this Marine Protected Area, diving can impact on the density, recruitment, survival, and the size of the colonies, registering lower values in frequented localities. Our results highlight that although Marine Protected Areas have been recognized as effective management and conservation tools to protect coastal ecosystems, the over frequentation of divers compromises the future viability of populations, highlighting the need to explore other management strategies.
In this context, for the first time in Chapter 5, different restoration techniques for bryozoans were developed and tested, focusing on the recruitment enhancement through the installation of recruitment surfaces and the transplantation of adult colonies of Pentapora fascialis. Plastic grids represented the best substrate in terms of facilitating the recruitment of our model species. The most successful technique to transplant adult colonies was to fix the colonies to the substrate with a nylon thread attached to the colony ex situ. The successful results and the affordable and economic cost of tested techniques aim to encourage the managers of Marine Protected Areas to apply similar methodologies to restore and conserve bryozoan temperate bioconstructions and the ecological services that they provide.
The results presented in this thesis show the importance to combine different approaches to understand the global and local ecological patterns of understudied but abundant groups, such as bryozoans. Our findings enlarge the current ecological knowledge of bryozoans at different scales, and highlight that more effort is needed to protect vulnerable populations. Accordingly, adaptive management formal plans and restoration actions are required to promote the conservation of marine communities in the context of increasing local and global stressors.