Marine defaunation: Animal loss in the global ocean

Fantastic Flatworms and Where to Find Them: Insights into Intertidal Polyclad Flatworm Distribution in Southeastern Australian Boulder Beaches

There is a rapid and extensive decline of our marine biodiversity due to human impacts. However, our ability to understand the extent of these effects is hindered by our lack of knowledge of the occurrence and ecology of some species groups. One such group of understudied organisms are marine flatworms of the order Polycladida, a conspicuous component of southeastern Australia’s marine ecosystems that has received little attention over the years. Intertidal boulder beaches support a diverse range of polyclad flatworms in other countries, but the role of these environments in maintaining biodiversity is not well understood. In this study, we identified hotspots of flatworm occurrence by assessing the diversity and overall abundance of flatworms at boulder beaches along the southeast Australian coast. Bottle and Glass, Sydney Harbour, was found to be the most diverse site for flatworms. We also identified a higher occurrence of flatworms under large boulders and less exposed beaches and noted an increased presence of flatworms at higher latitudes. Probable influences on these patterns such as the requirement for shelter and protection are discussed. This study contributes to our knowledge of Australia’s coastal biodiversity and can be used to assist in the management and conservation of our marine environments.

Impact assessment of human activities on resources of juvenile horseshoe crabs in Hainan coastal areas, China

The booming coastal zone economy poses increasing anthropogenic threats to marine life and habitats. Using the endangered living fossil horseshoe crab (HSC) as an example, we quantified the intensity of various anthropogenic pressures along the coast of Hainan Island, China, and for the first time assessed their impact on the distribution of juvenile HSCs through a field survey, remote sensing, spatial geographic modeling, and machine learning methods. The results indicate that the Danzhou Bay needs to be protected as a priority based on species and anthropogenic pressure information. Aquaculture and port activities dramatically impact the density of HSCs and therefore be managed priority. Finally, a threshold effect between total, coastal residential, and beach pressure and the density of juvenile HSCs were detected, which indicates the need for a balance between development and conservation as well as the designation of suitable sites for the construction of marine protected areas.

How predictable are mass extinction events?

Many modern extinction drivers are shared with past mass extinction events, such as rapid climate warming, habitat loss, pollution and invasive species. This commonality presents a key question: can the extinction risk of species during past mass extinction events inform our predictions for a modern biodiversity crisis? To investigate if it is possible to establish which species were more likely to go extinct during mass extinctions, we applied a functional trait-based model of extinction risk using a machine learning algorithm to datasets of marine fossils for the end-Permian, end-Triassic and end-Cretaceous mass extinctions. Extinction selectivity was inferred across each individual mass extinction event, before testing whether the selectivity patterns obtained could be used to 'predict' the extinction selectivity exhibited during the other mass extinctions. Our analyses show that, despite some similarities in extinction selectivity patterns between ancient crises, the selectivity of mass extinction events is inconsistent, which leads to a poor predictive performance. This lack of predictability is attributed to evolution in marine ecosystems, particularly during the Mesozoic Marine Revolution, associated with shifts in community structure alongside coincident Earth system changes. Our results suggest that past extinctions are unlikely to be informative for predicting extinction risk during a projected mass extinction.

Reduction in animal abundance and oxygen availability during and after the end-Triassic mass extinction

The end-Triassic biodiversity crisis was one of the most severe mass extinctions in the history of animal life. However, the extent to which the loss of taxonomic diversity was coupled with a reduction in organismal abundance remains to be quantified. Further, the temporal relationship between organismal abundance and local marine redox conditions is lacking in carbonate sections. To address these questions, we measured skeletal grain abundance in shallow-marine limestones by point counting 293 thin sections from four stratigraphic sections across the Triassic/Jurassic boundary in the Lombardy Basin and Apennine Platform of western Tethys. Skeletal abundance decreased abruptly across the Triassic/Jurassic boundary in all stratigraphic sections. The abundance of skeletal organisms remained low throughout the lower-middle Hettangian strata and began to rebound during the late Hettangian and early Sinemurian. A two-way ANOVA indicates that sample age (p < .01, η²  = 0.30) explains more of the variation in skeletal abundance than the depositional environment or paleobathymetry (p < .01, η²  = 0.15). Measured I/Ca ratios, a proxy for local shallow-marine redox conditions, show this same pattern with the lowest I/Ca ratios occurring in the early Hettangian. The close correspondence between oceanic water column oxygen levels and skeletal abundance indicates a connection between redox conditions and benthic organismal abundance across the Triassic/Jurassic boundary. These findings indicate that the end-Triassic mass extinction reduced not only the biodiversity but also the carrying capacity for skeletal organisms in early Hettangian ecosystems, adding to evidence that mass extinction of species generally leads to mass rarity among survivors.

Business for ocean sustainability: Early responses of ocean governance in the private sector

A large sample of 1664 companies-69 directly working in the ocean economy-distributed across 19 industrial sectors was investigated to explore awareness and activation regarding direct and indirect pressures on the ocean, their responses to these pressures, and the disclosure tools used. We examined their accountability and disclosure practices on sustainable development goals (SDGs) using the drivers, pressures, state, welfare, and response accounting framework. Based on their 2019 sustainability reports, just 7% of the companies assessed disclosed on SDG14. However, 51% of these companies can be considered as aware, albeit to varying degrees, of the pressures their industries place on the oceans, 44% deploy mitigating activities, and 26% are aware and actively lead business responses to ocean challenges. Although we have seen just early responses in addressing ocean challenges, companies' awareness and activation must converge to achieve ocean sustainability and move businesses into a truly blue economy.

Seagrass ecosystem multifunctionality under the rise of a flagship marine megaherbivore

Large grazers (megaherbivores) have a profound impact on ecosystem functioning. However, how ecosystem multifunctionality is affected by changes in megaherbivore populations remains poorly understood. Understanding the total impact on ecosystem multifunctionality requires an integrative ecosystem approach, which is especially challenging to obtain in marine systems. We assessed the effects of experimentally simulated grazing intensity scenarios on ecosystem functions and multifunctionality in a tropical Caribbean seagrass ecosystem. As a model, we selected a key marine megaherbivore, the green turtle, whose ecological role is rapidly unfolding in numerous foraging areas where populations are recovering through conservation after centuries of decline, with an increase in recorded overgrazing episodes. To quantify the effects, we employed a novel integrated index of seagrass ecosystem multifunctionality based upon multiple, well-recognized measures of seagrass ecosystem functions that reflect ecosystem services. Experiments revealed that intermediate turtle grazing resulted in the highest rates of nutrient cycling and carbon storage, while sediment stabilization, decomposition rates, epifauna richness, and fish biomass are highest in the absence of turtle grazing. In contrast, intense grazing resulted in disproportionally large effects on ecosystem functions and a collapse of multifunctionality. These results imply that (i) the return of a megaherbivore can exert strong effects on coastal ecosystem functions and multifunctionality, (ii) conservation efforts that are skewed toward megaherbivores, but ignore their key drivers like predators or habitat, will likely result in overgrazing-induced loss of multifunctionality, and (iii) the multifunctionality index shows great potential as a quantitative tool to assess ecosystem performance. Considerable and rapid alterations in megaherbivore abundance (both through extinction and conservation) cause an imbalance in ecosystem functioning and substantially alter or even compromise ecosystem services that help to negate global change effects. An integrative ecosystem approach in environmental management is urgently required to protect and enhance ecosystem multifunctionality.

Low genetic diversity and predation threaten a rediscovered marine sponge

Discovered in 1819 in the tropical waters off Singapore, the magnificent Neptune's cup sponge Cliona patera (Hardwicke, 1820) was harvested for museums and collectors until it was presumed extinct worldwide for over a century since 1907. Recently in 2011, seven living individuals were rediscovered in Singapore with six relocated to a marine protected area in an effort to better monitor and protect the population, as well as to enhance external fertilisation success. To determine genetic diversity within the population, we sequenced the complete mitochondrial genomes and nuclear ribosomal DNA of these six individuals and found extremely limited variability in their genes. The low genetic diversity of this rediscovered population is confirmed by comparisons with close relatives of C. patera and could compromise the population's ability to recover from environmental and anthropogenic pressures associated with the highly urbanised coastlines of Singapore. This lack of resilience is compounded by severe predation which has been shrinking sponge sizes by up to 5.6% every month. Recovery of this highly endangered population may require ex situ approaches and crossbreeding with other populations, which are also rare.

Unifying approaches to Functional Marine Connectivity for improved marine resource management: the European SEA-UNICORN COST Action

Truly sustainable development in a human-altered, fragmented marine environment subject to unprecedented climate change, demands informed planning strategies in order to be successful. Beyond a simple understanding of the distribution of marine species, data describing how variations in spatio-temporal dynamics impact ecosystem functioning and the evolution of species are required. Marine Functional Connectivity (MFC) characterizes the flows of matter, genes and energy produced by organism movements and migrations across the seascape. As such, MFC determines the ecological and evolutionary interdependency of populations, and ultimately the fate of species and ecosystems. Gathering effective MFC knowledge can therefore improve predictions of the impacts of environmental change and help to refine management and conservation strategies for the seas and oceans. Gathering these data are challenging however, as access to, and survey of marine ecosystems still presents significant challenge. Over 50 European institutions currently investigate aspects of MFC using complementary methods across multiple research fields, to understand the ecology and evolution of marine species. The aim of SEA-UNICORN, a COST Action supported by COST (European Cooperation in Science and Technology), is to bring together this research effort, unite the multiple approaches to MFC, and to integrate these under a common conceptual and analytical framework. The consortium brings together a diverse group of scientists to collate existing MFC data, to identify knowledge gaps, to enhance complementarity among disciplines, and to devise common approaches to MFC. SEA-UNICORN will promote co-working between connectivity practitioners and ecosystem modelers to facilitate the incorporation of MFC data into the predictive models used to identify marine conservation priorities. Ultimately, SEA-UNICORN will forge strong forward-working links between scientists, policy-makers and stakeholders to facilitate the integration of MFC knowledge into decision support tools for marine management and environmental policies.

Exploring the demography and conservation needs of hawksbill sea turtles Eretmochelys imbricata in north-west Mexico

The hawksbill sea turtle Eretmochelys imbricata is categorized as Critically Endangered on the IUCN Red List and its population has declined by over 80% in the last century. The Eastern Pacific population is one of the most threatened hawksbill populations globally. Western Mexico is the northern distribution limit for hawksbill sea turtles in the Eastern Pacific and recent research indicates that the Mexican Pacific portion of the population is a separate management unit because of the restricted movements of these turtles. Here we use the most complete database of sighting records in the north-west Pacific of Mexico to identify sites where hawksbill turtles are present. We also develop a conservation index to determine the conservation status of hawksbill turtle sites. Our results demonstrate the importance of this region for juveniles and the relevance of rocky reefs and mangrove estuaries as habitats for hawksbill turtles. We identified 52 sites with records of hawksbill turtles. Most of these sites (71%) are not protected; however, sites with high conservation value included islands and coastal sites along the Baja California peninsula that are established as marine protected areas. Reefs and mangrove estuaries relevant for hawksbill turtles are probably also significant fish nursery areas that are important for local fishing communities, creating opportunities for conservation strategies that combine science, local engagement and policy to benefit both local fishing communities and hawksbill sea turtle conservation.

The direct drivers of recent global anthropogenic biodiversity loss

Effective policies to halt biodiversity loss require knowing which anthropogenic drivers are the most important direct causes. Whereas previous knowledge has been limited in scope and rigor, here we statistically synthesize empirical comparisons of recent driver impacts found through a wide-ranging review. We show that land/sea use change has been the dominant direct driver of recent biodiversity loss worldwide. Direct exploitation of natural resources ranks second and pollution third; climate change and invasive alien species have been significantly less important than the top two drivers. The oceans, where direct exploitation and climate change dominate, have a different driver hierarchy from land and fresh water. It also varies among types of biodiversity indicators. For example, climate change is a more important driver of community composition change than of changes in species populations. Stopping global biodiversity loss requires policies and actions to tackle all the major drivers and their interactions, not some of them in isolation.

Good and bad news for ocean predators

Some tunas and billfishes are recovering, but sharks continue to decline

Seventy years of tunas, billfishes, and sharks as sentinels of global ocean health

Fishing activity is closely monitored to an increasing degree, but its effects on biodiversity have not received such attention. Using iconic and well-studied fish species such as tunas, billfishes, and sharks, we calculate a continuous Red List Index of yearly changes in extinction risk over 70 years to track progress toward global sustainability and biodiversity targets. We show that this well-established biodiversity indicator is highly sensitive and responsive to fishing mortality. After ~58 years of increasing risk of extinction, effective fisheries management has shifted the biodiversity loss curve for tunas and billfishes, whereas the curve continues to worsen for sharks, which are highly undermanaged. While populations of highly valuable commercial species are being rebuilt, the next management challenge is to halt and reverse the harm afflicted by these same fisheries to broad oceanic biodiversity.

Discovering marine biodiversity in the 21st century

We review the current knowledge of the biodiversity of the ocean as well as the levels of decline and threat for species and habitats. The lack of understanding of the distribution of life in the ocean is identified as a significant barrier to restoring its biodiversity and health. We explore why the science of taxonomy has failed to deliver knowledge of what species are present in the ocean, how they are distributed and how they are responding to global and regional to local anthropogenic pressures. This failure prevents nations from meeting their international commitments to conserve marine biodiversity with the results that investment in taxonomy has declined in many countries. We explore a range of new technologies and approaches for discovery of marine species and their detection and monitoring. These include: imaging methods, molecular approaches, active and passive acoustics, the use of interconnected databases and citizen science. Whilst no one method is suitable for discovering or detecting all groups of organisms many are complementary and have been combined to give a more complete picture of biodiversity in marine ecosystems. We conclude that integrated approaches represent the best way forwards for accelerating species discovery, description and biodiversity assessment. Examples of integrated taxonomic approaches are identified from terrestrial ecosystems. Such integrated taxonomic approaches require the adoption of cybertaxonomy approaches and will be boosted by new autonomous sampling platforms and development of machine-speed exchange of digital information between databases.

Temperature impacts on fish physiology and resource abundance lead to faster growth but smaller fish sizes and yields under warming

Resolving the combined effect of climate warming and exploitation in a food web context is key for predicting future biomass production, size-structure and potential yields of marine fishes. Previous studies based on mechanistic size-based food web models have found that bottom-up processes are important drivers of size-structure and fisheries yield in changing climates. However, we know less about the joint effects of 'bottom-up' and physiological effects of temperature; how do temperature effects propagate from individual-level physiology through food webs and alter the size-structure of exploited species in a community? Here, we assess how a species-resolved size-based food web is affected by warming through both these pathways and by exploitation. We parameterize a dynamic size spectrum food web model inspired by the offshore Baltic Sea food web, and investigate how individual growth rates, size-structure, and relative abundances of species and yields are affected by warming. The magnitude of warming is based on projections by the regional coupled model system RCA4-NEMO and the RCP 8.5 emission scenario, and we evaluate different scenarios of temperature dependence on fish physiology and resource productivity. When accounting for temperature-effects on physiology in addition to on basal productivity, projected size-at-age in 2050 increases on average for all fish species, mainly for young fish, compared to scenarios without warming. In contrast, size-at-age decreases when temperature affects resource dynamics only, and the decline is largest for young fish. Faster growth rates due to warming, however, do not always translate to larger yields, as lower resource carrying capacities with increasing temperature tend to result in decline in the abundance of larger fish and hence spawning stock biomass. These results suggest that to understand how global warming affects the size structure of fish communities, both direct metabolic effects and indirect effects of temperature via basal resources must be accounted for.

Phylogeny explains capture mortality of sharks and rays in pelagic longline fisheries: a global meta-analytic synthesis

Apex and mesopredators such as elasmobranchs are important for maintaining ocean health and are the focus of conservation efforts to mitigate exposure to fishing and other anthropogenic hazards. Quantifying fishing mortality components such as at-vessel mortality (AVM) is necessary for effective bycatch management. We assembled a database for 61 elasmobranch species and conducted a global meta-synthesis to estimate pelagic longline AVM rates. Evolutionary history was a significant predictor of AVM, accounting for up to 13% of variance in Bayesian phylogenetic meta-regression models for Lamniformes and Carcharhiniformes clades. Phylogenetically related species may have a high degree of shared traits that explain AVM. Model-estimated posterior mean AVM rates ranged from 5% (95% HDI 0.1%-16%) for pelagic stingrays and 76% (95% HDI 49%-90%) for salmon sharks. Measures that reduce catch, and hence AVM levels, such as input controls, bycatch quotas and gear technology to increase selectivity are appropriate for species with higher AVM rates. In addition to reducing catchability, handling-and-release practices and interventions such as retention bans in shark sanctuaries and bans on shark finning and trade hold promise for species with lower AVM rates. Robust, and where applicable, phylogenetically-adjusted elasmobranch AVM rates are essential for evidence-informed bycatch policy.

Samaki Salama - Promoting healthy child growth and sustainable fisheries in coastal Kenya: A study protocol

Background

One in five young children globally suffer the consequences of stunted growth and development and millions experience deficiencies in zinc, iron, iodine, vitamins A and B12, nutrients found bioavailable in fish foods. Small-scale fisheries have the potential to generate income and augment fish consumption while being environmentally sustainable if appropriately managed. However, those engaged in small-scale fisheries are often marginalized, poor, and malnourished. The Samaki Salama project seeks to better understand and address these challenges through a three-arm, longitudinal matched cluster study which evaluates the impact of an integrated nutrition social marketing and modified fishing trap intervention.

Methods

There will be 400 small-scale fisher households enrolled from Kilifi County, Kenya and residing in communities matched on location (rural), livelihoods, and child nutritional status. The sample will include mothers and other caregivers, children 6-60 months, and fishers in the family. Applying a cluster design, the matched communities will be divided into three groups: (1) control (n = 200); (2) multi-component nutrition social marketing intervention to fishers, mothers, and health workers (n = 100); and (3) multi-component nutrition social marketing intervention plus modified fishing traps and training (n = 100). Primary outcomes include child growth, fish food intakes, and fisheries yield of mature fish. Secondary outcomes are diet diversity, child diarrheal morbidity, and fisheries revenue. A process evaluation will be used to monitor and ensure fidelity of intervention delivery.

Discussion

This study builds on a growing body of literature illustrating the effectiveness of nutrition focused social marketing campaigns to promote active engagement of participants, high compliance to the intervention, and sustained behavior change. The second intervention element of modified fishing traps that allow immature fish to escape enables participants to act on the messaging they receive and promotes sustainable fishing through increased harvest efficiency and reduced catch of immature fish. The integrated approach of the Samaki Salama intervention provides an example of how to leverage multiple disciplines to address key challenges to human and environmental health and illustrates a pathway for scaling study innovations to other small-scale fisheries systems.

Trial registration

https://clinicaltrials.gov (NCT05254444).

Marine mammal conservation in the 21st century: A plea for a paradigm shift towards mindful conservation

Marine mammals are regarded in high esteem by the general public, and are recognized as flagship species for conservation, while at the same time they suffer from anthropogenic impacts on a global scale, and often in extreme ways. It seems there is a huge discrepancy between how we humans think about our fellow creatures in the sea, and how we behave to impact and/or conserve them. Here, I examine why the purely scientific and thus intellectual approach to marine mammal conservation has had limited success over the past decades. While there are some obvious success stories in cetacean conservation, the situation today is, for many species and populations, more dire than it has ever been. The idea of 'we need to know more'-a credo of the scientific community-often is politically misrepresented to postpone necessary conservation decisions. To adapt our path towards more profound and, importantly, more effective marine conservation, as conservationists we need to go deeper and change the narrative of separation, i.e., the concept of humans being set apart from the rest of nature. Instead, there is a need to create a narrative of connectedness, i.e., the consciousness of humans being an integral part of the planetary system. Rather than telling horror stories about the plight of marine mammals, conservationists also need to trigger positive emotions about them in ourselves. More holistic aspects of conservation need to be incorporated in our future efforts, including the fuller integration of traditional knowledge and indigenous wisdom, recognizing ecosystem functions of marine life and protecting the processes they sustain, respecting 'holiness' of nature while focusing on the animals' individuality, personhood and the cultural identity of distinct communities. Effective marine mammal conservation will be possible only on the basis of a profound change of our own values and a fundamental change of the societal system we are living in.

Five actionable pillars to engage the next generation of leaders in the co-design of transformative ocean solutions

Solutions to complex and unprecedented global challenges are urgently needed. Overcoming these challenges requires input and innovative solutions from all experts, including Early Career Ocean Professionals (ECOPs). To achieve diverse inclusion from ECOPs, fundamental changes must occur at all levels—from individuals to organizations. Drawing on insights from across the globe, we propose 5 actionable pillars that support the engagement of ECOPs in co-design processes that address ocean sustainability: sharing knowledge through networks and mentorship, providing cross-boundary training and opportunities, incentivizing and celebrating knowledge co-design, creating inclusive and participatory governance structures, and catalyzing culture change for inclusivity. Foundational to all actions are the cross-cutting principles of justice, equity, diversity, and inclusivity. In addition, the pillars are cross-boundary in nature, including collaboration and innovation across sectors, disciplines, regions, generations, and backgrounds. Together, these recommendations provide an actionable and iterative path toward inclusive engagement and intergenerational exchange that can develop ocean solutions for a sustainable future.

Early Career Ocean Professionals (ECOPs) need to engage in co-design processes that address ocean sustainability. This Consensus View proposes five pillars to provide an actionable and iterative path toward inclusive engagement and intergenerational exchange that can develop ocean solutions for a sustainable future.

Fishing for fish environmental DNA: Ecological applications, methodological considerations, surveying designs, and ways forward

Vast global declines of freshwater and marine fish diversity and population abundance pose serious threats to both ecosystem sustainability and human livelihoods. Environmental DNA (eDNA)-based biomonitoring provides robust, efficient, and cost-effective assessment of species occurrences and population trends in diverse aquatic environments. Thus, it holds great potential for improving conventional surveillance frameworks to facilitate fish conservation and fisheries management. However, the many technical considerations and rapid developments underway in the eDNA arena can overwhelm researchers and practitioners new to the field. Here, we systematically analysed 416 fish eDNA studies to summarize research trends in terms of investigated targets, research aims, and study systems, and reviewed the applications, rationales, methodological considerations, and limitations of eDNA methods with an emphasis on fish and fisheries research. We highlighted how eDNA technology may advance our knowledge of fish behaviour, species distributions, population genetics, community structures, and ecological interactions. We also synthesized the current knowledge of several important methodological concerns, including the qualitative and quantitative power eDNA has to recover fish biodiversity and abundance, and the spatial and temporal representations of eDNA with respect to its sources. To facilitate ecological applications implementing fish eDNA techniques, recent literature was summarized to generate guidelines for effective sampling in lentic, lotic, and marine habitats. Finally, we identified current gaps and limitations, and pointed out newly emerging research avenues for fish eDNA. As methodological optimization and standardization improve, eDNA technology should revolutionize fish monitoring and promote biodiversity conservation and fisheries management that transcends geographic and temporal boundaries.

Landscape genomics of the American lobster (Homarus americanus)

In marine species experiencing intense fishing pressures, knowledge of genetic structure and local adaptation represent a critical information to assist sustainable management. In this study, we performed a landscape genomics analysis in the American lobster to investigate the issues pertaining to the consequences of making use of putative adaptive loci to reliably infer population structure and thus more rigorously delineating biological management units in marine exploited species. Toward this end, we genotyped 14,893 single nucleotide polymorphism (SNPs) in 4190 lobsters sampled across 96 sampling sites distributed along 1000 km in the northwest Atlantic in both Canada and the USA. As typical for most marine species, we observed a weak, albeit highly significant genetic structure. We also found that adaptive genetic variation allows detecting fine-scale population structure not resolved by neutral genetic variation alone. Using the recent genome assembly of the American lobster, we were able to map and annotate several SNPs located in functional genes potentially implicated in adaptive processes such as thermal stress response, salinity tolerance and growth metabolism pathways. Taken together, our study indicates that weak population structure in high gene flow systems can be resolved at various spatial scales, and that putatively adaptive genetic variation can substantially enhance the delineation of biological management units of marine exploited species.

Evaluation of artificial reef habitats as reconstruction or enhancement tools of benthic fish communities in northern Yellow Sea

Artificial reefs have been widely deployed in the northern Yellow Sea. However, the differences in the ecological benefits on different types of artificial reef habitats are still poorly understood. In this study, the temporal and spatial differences on benthic fish communities were evaluated among concrete artificial reef habitat (CAR), rocky artificial reef habitat (RAR), ship artificial reef habitat (SAR) around Xiaoshi Island in northern Yellow Sea. The results indicated that all three types of artificial reef habitats can enhance the diversity variables of benthic fish communities, and fish abundance, species richness and Shannon-Wiener index of CAR were generally better than the other two. CAR and RAR hosted similar community composition of benthic fish, and all types of habitats showed significant differences in community composition between winter-spring and summer-autumn. Environmental factors, especially water temperature, can also affect the community composition by affecting the migration of temperature-preferred species. Overall, the enhancement effects of artificial habitats on fisheries productivity varied with fish species and reef types. This study will help to understand the ecological effects of different types of artificial reefs in northern Yellow Sea, and then could give an insight for scientific construction of artificial reefs in this region.

Social science for conservation in working landscapes and seascapes

Biodiversity is in precipitous decline globally across both terrestrial and marine environments. Therefore, conservation actions are needed everywhere on Earth, including in the biodiversity rich landscapes and seascapes where people live and work that cover much of the planet. Integrative landscape and seascape approaches to conservation fill this niche. Making evidence-informed conservation decisions within these populated and working landscapes and seascapes requires an in-depth and nuanced understanding of the human dimensions through application of the conservation social sciences. Yet, there has been no comprehensive exploration of potential conservation social science contributions to working landscape and seascape initiatives. We use the Smithsonian Working Land and Seascapes initiative – an established program with a network of 14 sites around the world – as a case study to examine what human dimensions topics are key to improving our understanding and how this knowledge can inform conservation in working landscapes and seascapes. This exploratory study identifies 38 topics and linked questions related to how insights from place-based and problem-focused social science might inform the planning, doing, and learning phases of conservation decision-making and adaptive management. Results also show how conservation social science might yield synthetic and theoretical insights that are more broadly applicable. We contend that incorporating insights regarding the human dimensions into integrated conservation initiatives across working landscapes and seascapes will produce more effective, equitable, appropriate and robust conservation actions. Thus, we encourage governments and organizations working on conservation initiatives in working landscapes and seascapes to increase engagement with and funding of conservation social science.

Circling the drain: the extinction crisis and the future of humanity

Humanity has triggered the sixth mass extinction episode since the beginning of the Phanerozoic. The complexity of this extinction crisis is centred on the intersection of two complex adaptive systems: human culture and ecosystem functioning, although the significance of this intersection is not properly appreciated. Human beings are part of biodiversity and elements in a global ecosystem. Civilization, and perhaps even the fate of our species, is utterly dependent on that ecosystem's proper functioning, which society is increasingly degrading. The crisis seems rooted in three factors. First, relatively few people globally are aware of its existence. Second, most people who are, and even many scientists, assume incorrectly that the problem is primarily one of the disappearance of species, when it is the existential threat of myriad population extinctions. Third, while concerned scientists know there are many individual and collective steps that must be taken to slow population extinction rates, some are not willing to advocate the one fundamental, necessary, 'simple' cure, that is, reducing the scale of the human enterprise. We argue that compassionate shrinkage of the human population by further encouraging lower birth rates while reducing both inequity and aggregate wasteful consumption-that is, an end to growthmania-will be required. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'.

Ecological complexity and the biosphere: the next 30 years

Global warming, habitat loss and overexploitation of limited resources are leading to alarming biodiversity declines. Ecosystems are complex adaptive systems that display multiple alternative states and can shift from one to another in abrupt ways. Some of these tipping points have been identified and predicted by mathematical and computational models. Moreover, multiple scales are involved and potential mitigation or intervention scenarios are tied to particular levels of complexity, from cells to human–environment coupled systems. In dealing with a biosphere where humans are part of a complex, endangered ecological network, novel theoretical and engineering approaches need to be considered. At the centre of most research efforts is biodiversity, which is essential to maintain community resilience and ecosystem services. What can be done to mitigate, counterbalance or prevent tipping points? Using a 30-year window, we explore recent approaches to sense, preserve and restore ecosystem resilience as well as a number of proposed interventions (from afforestation to bioengineering) directed to mitigate or reverse ecosystem collapse. The year 2050 is taken as a representative future horizon that combines a time scale where deep ecological changes will occur and proposed solutions might be effective.

This article is part of the theme issue ‘Ecological complexity and the biosphere: the next 30 years’.

Small-scale fisheries catch more threatened elasmobranchs inside partially protected areas than in unprotected areas

Elasmobranchs are heavily impacted by fishing. Catch statistics are grossly underestimated due to missing data from various fishery sectors such as small-scale fisheries. Marine Protected Areas are proposed as a tool to protect elasmobranchs and counter their ongoing depletion. We assess elasmobranchs caught in 1,256 fishing operations with fixed nets carried out in partially protected areas within Marine Protected Areas and unprotected areas beyond Marine Protected Areas borders at 11 locations in 6 Mediterranean countries. Twenty-four elasmobranch species were recorded, more than one-third belonging to the IUCN threatened categories (Vulnerable, Endangered, or Critically Endangered). Catches per unit of effort of threatened and data deficient species were higher (with more immature individuals being caught) in partially protected areas than in unprotected areas. Our study suggests that despite partially protected areas having the potential to deliver ecological benefits for threatened elasmobranchs, poor small-scale fisheries management inside Marine Protected Areas could hinder them from achieving this important conservation objective.

The sixth R: Revitalizing the natural phosphorus pump

Phosphorus (P) is essential for all life on Earth and sustains food production. Yet, the easily accessible deposits of phosphate-rich rock, which underpin the green revolution are becoming rarer. Here we propose a mechanism to help alleviate the problem of "peak phosphorus". In the past, wild animals played a large role in returning P from ocean depths back to the continental interiors. In doing so, they collectively retained and redistributed P within the biosphere, supporting a more fertile planet. However, species extinctions and population reductions have reduced animal-mediated P transport >90% over the past 12,000 years. Recently a 5R strategy was developed to Realign P inputs, Reduce P losses, Recycle P in bio-resources, Recover P in wastes, and Redefine P in food systems. Here, we suggest a sixth R, to Revitalize the Natural Phosphorus Pump (RNPP). Countries are starting to mandate P recycling and we propose a P-trading scheme based on REDD+, where a country could partially achieve its recycling goals by restoring past animal-mediated P pathways. Accrued money from this scheme could be used to restore or conserve wild animal populations, while increasing natural P recycling.

Glimmers of hope in large carnivore recoveries

In the face of an accelerating extinction crisis, scientists must draw insights from successful conservation interventions to uncover promising strategies for reversing broader declines. Here, we synthesize cases of recovery from a list of 362 species of large carnivores, ecologically important species that function as terminal consumers in many ecological contexts. Large carnivores represent critical conservation targets that have experienced historical declines as a result of direct exploitation and habitat loss. We examine taxonomic and geographic variation in current extinction risk and recovery indices, identify conservation actions associated with positive outcomes, and reveal anthropogenic threats linked to ongoing declines. We find that fewer than 10% of global large carnivore populations are increasing, and only 12 species (3.3%) have experienced genuine improvement in extinction risk, mostly limited to recoveries among marine mammals. Recovery is associated with species legislation enacted at national and international levels, and with management of direct exploitation. Conversely, ongoing declines are robustly linked to threats that include habitat modification and human conflict. Applying lessons from cases of large carnivore recovery will be crucial for restoring intact ecosystems and maintaining the services they provide to humans.

Conceptualisation of multiple impacts interacting in the marine environment using marine infrastructure as an example

The human population is increasingly reliant on the marine environment for food, trade, tourism, transport, communication and other vital ecosystem services. These services require extensive marine infrastructure, all of which have direct or indirect ecological impacts on marine environments. The rise in global marine infrastructure has led to light, noise and chemical pollution, as well as facilitation of biological invasions. As a result, marine systems and associated species are under increased pressure from habitat loss and degradation, formation of ecological traps and increased mortality, all of which can lead to reduced resilience and consequently increased invasive species establishment. Whereas the cumulative bearings of collective human impacts on marine populations have previously been demonstrated, the multiple impacts associated with marine infrastructure have not been well explored. Here, building on ecological literature, we explore the impacts that are associated with marine infrastructure, conceptualising the notion of correlative, interactive and cumulative effects of anthropogenic activities on the marine environment. By reviewing the range of mitigation approaches that are currently available, we consider the role that eco-engineering, marine spatial planning and agent-based modelling plays in complementing the design and placement of marine structures to incorporate the existing connectivity pathways, ecological principles and complexity of the environment. Because the effect of human-induced, rapid environmental change is predicted to increase in response to the growth of the human population, this study demonstrates that the development and implementation of legislative framework, innovative technologies and nature-informed solutions are vital, preventative measures to mitigate the multiple impacts associated with marine infrastructure.

Influence of climate change and extreme weather events on an estuarine fish community

Extreme weather events are becoming more frequent as a result of climate change, and the increasing frequency of these events may lead to significant changes in fish assemblages. In this sense, this work aimed to study the effects of climate change and extreme weather events on fish assemblages in the Rio Minho estuary (Portugal). Between 2010 and 2019, continuous weekly sampling with fyke nets was carried out to assess the dynamics of fish assemblages in the estuary. In addition, temperature and precipitation data were obtained from satellite information to assess the relationship between climatic variables and fish composition, structure, and diversity. Fish populations changed significantly over time, becoming less diverse and largely dominated by a few, mostly invasive species (e.g., carp, goldfish, pumpkinseed, and tench), while the abundance of most native species declined over the years (e.g., panjorca, stickleback, and shad). High temperatures and low precipitation negatively affected native species, while the invasive species benefited from increased temperatures and extreme weather events (droughts and floods).

Temperature Controls eDNA Persistence across Physicochemical Conditions in Seawater

Environmental DNA (eDNA) quantification and sequencing are emerging techniques for assessing biodiversity in marine ecosystems. Environmental DNA can be transported by ocean currents and may remain at detectable concentrations far from its source depending on how long it persist. Thus, predicting the persistence time of eDNA is crucial to defining the spatial context of the information derived from it. To investigate the physicochemical controls of eDNA persistence, we performed degradation experiments at temperature, pH, and oxygen conditions relevant to the open ocean and the deep sea. The eDNA degradation process was best explained by a model with two phases with different decay rate constants. During the initial phase, eDNA degraded rapidly, and the rate was independent of physicochemical factors. During the second phase, eDNA degraded slowly, and the rate was strongly controlled by temperature, weakly controlled by pH, and not controlled by dissolved oxygen concentration. We demonstrate that marine eDNA can persist at quantifiable concentrations for over 2 weeks at low temperatures (≤10 °C) but for a week or less at ≥20 °C. The relationship between temperature and eDNA persistence is independent of the source species. We propose a general temperature-dependent model to predict the maximum persistence time of eDNA detectable through single-species eDNA quantification methods.

Updated Trends on the Biodiscovery of New Marine Natural Products from Invertebrates

From 1990–2019, a total of 15,442 New Marine Natural Products from Invertebrates (NMNPIs) were reported. The 2010s saw the most prolific decade of biodiscovery, with 5630 NMNPIs recorded. The phyla that contributed most biomolecules were the Porifera (sponges) (47.2%, 2659 NMNPIs) and the Cnidaria (35.3%, 1989 NMNPIs). The prevalence of these two phyla as the main sources of NMNPIs became more pronounced in the 2010s. The tropical areas of the Pacific Ocean yielded more NMNPIs, most likely due to the remarkable biodiversity of coral reefs. The Indo-Burma biodiversity hotspot (BH) was the most relevant area for the biodiscovery of NMNPIs in the 2010s, accounting for nearly one-third (1819 NMNPIs) of the total and surpassing the top BH from the 1990s and the 2000s (the Sea of Japan and the Caribbean Islands, respectively). The Chinese exclusive economic zone (EEZ) alone contributed nearly one-quarter (24.7%) of all NMNPIs recorded during the 2010s, displacing Japan’s leading role from the 1990s and the 2000s. With the biodiscovery of these biomolecules steadily decreasing since 2012, it is uncertain whether this decline has been caused by lower bioprospecting efforts or the potential exhaustion of chemodiversity from traditional marine invertebrate sources.

Changes in mean body size in an expanding population of a threatened species

With some taxa, a reduction in the mean size of individuals may reflect over-harvesting and/or trophy hunting. However, we show that in sea turtles, a reduction in the mean size of breeding individuals may be part of the good news story of an expanding population. We describe a 70-fold increase in annual nest numbers on the island of Sal (Cape Verde, North Atlantic) between 2008 and 2020 (from 506 to 35 507 nests), making this now one of the largest loggerhead (Caretta caretta) nesting aggregations in the world. We use 20 128 measurements of the size of nesting turtles to show that their mean annual size has decreased by about 2.4 cm, from 83.2 to 80.8 cm. This decrease in the mean size of nesting turtles was not caused by the removal of larger turtles, for example by selective harvesting. Rather we develop a theoretical model to show than this decrease in mean size can be explained by an influx of first-time nesters, combined with a decrease in the size of those first-time nesters over time. A reduction in mean size of nesting turtles has been reported across the Atlantic, Pacific and Indian Oceans, and may be a common feature of population recoveries in sea turtles.

Important marine areas for endangered African penguins before and after the crucial stage of moulting

The population of the Endangered African penguin Spheniscus demersus has decreased by > 65% in the last 20 years. A major driver of this decrease has been the reduced availability of their principal prey, sardine Sardinops sagax and anchovy Engraulis encrasicolus. To date, conservation efforts to improve prey availability have focused on spatial management strategies to reduce resource competition with purse-seine fisheries during the breeding season. However, penguins also undergo an annual catastrophic moult when they are unable to feed for several weeks. Before moulting they must accumulate sufficient energy stores to survive this critical life-history stage. Using GPS tracking data collected between 2012 and 2019, we identify important foraging areas for pre- and post-moult African penguins at three of their major colonies in South Africa: Dassen Island and Stony Point (Western Cape) and Bird Island (Eastern Cape). The foraging ranges of pre- and post-moult adult African penguins (c. 600 km from colony) was far greater than that previously observed for breeding penguins (c. 50 km from colony) and varied considerably between sites, years and pre- and post-moult stages. Despite their more extensive range during the non-breeding season, waters within 20 and 50 km of their breeding colonies were used intensively and represent important foraging areas to pre- and post-moult penguins. Furthermore, penguins in the Western Cape travelled significantly further than those in the Eastern Cape which is likely a reflection of the poor prey availability along the west coast of South Africa. Our findings identify important marine areas for pre- and post-moult African penguins and support for the expansion of fisheries-related spatio-temporal management strategies to help conserve African penguins outside the breeding season.

Unifying climate change biology across realms and taxa

A major challenge in modern biology is to understand extinction risk from climate change across all realms. Recent research has revealed that physiological tolerance, behavioral thermoregulation, and small elevation shifts are dominant coping strategies on land, whereas large-scale latitudinal shifts are more important in the ocean. Freshwater taxa may face the highest global extinction risks. Nevertheless, some species in each realm face similar risks because of shared adaptive, dispersal, or physiological tolerances and abilities. Taking a cross-realm perspective offers unique research opportunities because confounding physical factors in one realm are often disaggregated in another realm. Cross-realm, across taxa, and other forms of climate change biology synthesis are needed to advance our understanding of emergent patterns of risk across all life.

Reef larval recruitment in response to seascape dynamics in the SW Atlantic

Advances in satellite observation have improved our capacity to track changes in the ocean with numerous ecological and conservation applications, which are yet under-explored for coastal ecology. In this study, we assessed the spatio-temporal dynamics in invertebrate larval recruitment and the Seascape Pelagic Habitat Classification, a satellite remote-sensing product developed by the Marine Biodiversity Observation Network (MBON) and delivered by the US National Oceanic and Atmospheric Administration to monitor biodiversity globally. Our ultimate goal was to identify and predict changes in coastal benthic assemblages at tropical reefs in the SW Atlantic based on integrated pelagic conditions, testing the use of MBON Seascape categorization. Our results revealed that the pelagic Seascapes correlated with monthly and seasonal variations in recruitment rates and assemblage composition. Recruitment was strongly influenced by subtropical Seascapes and was reduced by the presence of warm waters with high-nutrient contents and phytoplankton blooms, which are likely to affect reef communities in the long term. Recruitment modeling indicates that Seascapes may be more efficient than sea surface temperature in predicting benthic larval dynamics. Based on historical Seascape patterns, we identified seven events that may have impacted benthic recruitment in this region during the last decades. These findings provide new insights into the application of novel satellite remote-sensing Seascape categorizations in benthic ecology and evidence how reef larval supply in the SW Atlantic could be impacted by recent and future ocean changes.

Predictions of sardine and the Portuguese continental shelf ecosystem dynamics under future fishing, forced-biomass and SST scenarios

We used the Ecopath with Ecosim ecosystem model to assess the future effects of multiple stressors on sardine and the Portuguese continental shelf ecosystem. We assessed individual and combined impacts of changes in sardine fishing pressure, biomass of sardine competitors and predators and sea surface temperature (SST). This study demonstrated that the greatest impact on sardine stock is caused by projected SST rise whose effect is dominant and detrimental to sardine stock regardless of other conditions, including sardine fishing at maximum sustainable yield (FMSY). The largest impact on ecosystem stability, maturity and diversity of flows was observed under the forced-biomass scenarios that simulate changes in biomass of sardine predators and competitors. Moreover, these stressors alongside FMSY are projected to play an important role in the future evolution of the sardine stock. Results presented in this study can assist long-term and strategic management of the Iberian sardine stock.

A stark future for ocean life

Model predicts a mass extinction event in the oceans if climate change is uncurbed.

Avoiding ocean mass extinction from climate warming

Global warming threatens marine biota with losses of unknown severity. Here, we quantify global and local extinction risks in the ocean across a range of climate futures on the basis of the ecophysiological limits of diverse animal species and calibration against the fossil record. With accelerating greenhouse gas emissions, species losses from warming and oxygen depletion alone become comparable to current direct human impacts within a century and culminate in a mass extinction rivaling those in Earth's past. Polar species are at highest risk of extinction, but local biological richness declines more in the tropics. Reversing greenhouse gas emissions trends would diminish extinction risks by more than 70%, preserving marine biodiversity accumulated over the past ~50 million years of evolutionary history.

Transcending capitalism growth strategies for biodiversity conservation

The unlimited economic growth that fuels capitalism's metabolism has profoundly transformed a large portion of Earth. The resulting environmental destruction has led to an unprecedented rate of biodiversity loss. Following large-scale losses of habitats and species, it was recognized that biodiversity is crucial to maintaining functional ecosystems. We sought to continue the debate on the contradictions between economic growth and biodiversity in the conservation science literature and thus invite scholars to engage in reversing the biodiversity crisis through acknowledging the impacts of economic growth. In the 1970s, a global agenda was set to develop different milestones related to sustainable development, including green-blue economic growth, which despite not specifically addressing biodiversity reinforced the idea that economic development based on profit is compatible with the planet's ecology. Only after biodiversity loss captured the attention of environmental sciences researchers in the early 2000s was a global biodiversity agenda implemented. The agenda highlights biodiversity conservation as a major international challenge and recognizes that the main drivers of biodiversity loss derive from economic activities. The post-2000 biodiversity agendas, including the 2030 Agenda for Sustainable Development and the post-2020 Convention on Biological Diversity Global Strategy Framework, do not consider the negative impacts of growth-oriented strategies on biodiversity. As a result, global biodiversity conservation priorities are governed by the economic value of biodiversity and its assumed contribution to people's welfare. A large body of empirical evidence shows that unlimited economic growth is the main driver of biodiversity loss in the Anthropocene; thus, we strongly argue for sustainable degrowth and a fundamental shift in societal values. An equitable downscaling of the physical economy can improve ecological conditions, thus reducing biodiversity loss and consequently enhancing human well-being.

Characterizing the oral and distal gut microbiota of the threatened southern sea otter (Enhydra lutris nereis) to enhance conservation practice

The southern sea otter (Enhydra lutris nereis) is a threatened sub-species in coastal ecosystems. To understand better the role of diet, monitor health, and enhance management of this and other marine mammal species, we characterized the oral (gingival) and distal gut (rectal and fecal) microbiota of 158 wild southern sea otters living off the coast of central California, USA, and 12 captive sea otters, some of which were included in a diet shift experiment. We found that the sea otter fecal microbiota was distinct from that of three other otter species, and that captivity does not significantly alter the community structure of the sea otter gingival or distal gut microbiota. Metagenomic analysis unexpectedly revealed that the majority of sea otter fecal DNA is derived from prey, rather than from indigenous bacteria or host cells as with most other mammals. We speculate that a reduced bacterial biomass in the sea otter gut reflects rapid gut transit time and a particular strategy for foraging and energy harvest. This study establishes a reference for the healthy sea otter microbiota, highlights how a marine lifestyle may shape the mammalian microbiota, and may inform future health assessments and conservation management of sea otter populations.

Checklist of decapod crustaceans from the coast of the São Paulo state (Brazil) supported by integrative molecular and morphological data: V. Dendrobranchiata and Pleocyemata [Achelata, Astacidea, Axiidea, Caridea (Alpheoidea and Processoidea excluded), Gebiidea, Stenopodidea]

This checklist is the fifth and last compilation on the decapod crustaceans reported to São Paulo (Brazil) coastal area, resulting from long-term multidisciplinary projects, which combined morphological analyses and molecular techniques. The current research includes 75 decapod species, herein referred as shrimps/lobsters-like (shrimps, ghost-shrimps, lobsters, and related groups), reported to São Paulo coastal area. These species occur in marine, estuarine, and amphidromous habitats and are classified into 21 families as follow: Aristeidae (2 spp., 2 genera), Atyidae (4 spp., 2 genera), Axianassidae (1 sp., 1 genus), Callianassidae (1 sp., 1 genus), Callichiridae (6 spp., 4 genera), Crangonidae (1 sp., 1 genus), Glyphocrangonidae (1 sp., 1 genus), Luciferidae (2 spp., 2 genera), Nephropidae (4 spp., 2 genera), Palaemonidae (15 spp., 9 genera), Palinuridae (2 spp., 1 genus), Pandalidae (1 sp., 1 genus), Pasiphaeidae (1 sp., 1 genus), Penaeidae (10 spp., 6 genera), Sergestidae (3 spp., 3 genera), Sicyoniidae (4 spp., 1 genus), Scyllaridae (5 spp., 3 genera), Solenoceridae (4 spp., 3 genera), Stenopodidae (2 spp., 1 genus), and Upogebiidae (6 spp., 1 genus). We generated new sequences of cytochrome oxidase subunit I (barcode region) and 16S genes (51 and 54, respectively) of 54 species. Our examination concluded that 75 shrimps/lobsters-like species are reported to the São Paulo coast. We excluded Leander tenuicornis (Palaemonidae), Penaeus setiferus (Penaeidae), Philocheras gorei (Crangonidae), and Rhynchocinetes typus (Rhynchocinetidae) from this list.  

Enhancing multiple scales of seafloor biodiversity with mussel restoration

Restoration projects are underway internationally in response to global declines in shellfish beds. As diverse biological assemblages underpin a variety of ecosystem services, understanding broader changes in biodiversity associated with mussel restoration becomes increasingly valuable to scientists and restoration practitioners. Studies generally show bivalve beds increase species richness and abundance, but results are scale-dependent and conditional on the mobility of specific communities observed. We examined biodiversity at multiple scales to determine how communities with varying levels of mobility are influenced by subtidal mussel restoration. Significant changes in assemblage structure were observed in both mobile fish and epifaunal communities, with enhanced species richness and total abundance of associated individuals. In contrast, we observed site-dependent effects of bivalve restoration on macrofaunal community structure and composition, with sheltered, harbour mussel bed communities numerically dominated by detritivores accustomed to organically enriched, muddy sediments. Sediment organic matter significantly increased within mussel beds, and distance-based linear models showed that sediment organic matter was an important predictor of macrofaunal assemblage structure on mussel beds, highlighting the significance of benthic-pelagic coupling and biodeposition to soft-sediment communities. This study contributes novel methods and ecological insights on the role of species mobility and site selection in structuring restoration outcomes, better informing future mussel restoration efforts aimed at emphasising functionally-driven ecosystem services.