Identifying priority sites for whale shark ship collision management globally

The expansion of the world's merchant fleet poses a great threat to the ocean's biodiversity. Collisions between ships and marine megafauna can have population-level consequences for vulnerable species. The Endangered whale shark (Rhincodon typus), shares a circumglobal distribution with this expanding fleet and tracking of movement pathways has shown that large vessel collisions pose a major threat to the species. However, it is not yet known whether they are also at risk within aggregation sites, where up to 400 individuals can gather to feed on seasonal bursts of planktonic productivity. These "constellation" sites are of significant ecological, socio-economic and cultural value. Here, through expert elicitation, we gathered information from most known constellation sites for this species across the world (>50 constellations and >13,000 individual whale sharks). We defined the spatial boundaries of these sites and their overlap with shipping traffic. Sites were then ranked based on relative levels of potential collision danger posed to whale sharks in the area. Our results showed that researchers and resource managers may underestimate the threat posed by large ship collisions due to a lack of direct evidence, such as injuries or witness accounts, which are available for other, sub-lethal threat categories. We found that constellations in the Arabian Sea and adjacent waters, the Gulf of Mexico, the Gulf of California, and Southeast and East Asia, had the greatest level of vessel collision threat. We also identified 39 sites where peaks in shipping activity coincided with peak seasonal occurrences of whale sharks, sometimes across several months. Simulated potential collision mitigation options estimated a minimal impact to industry, as most whale shark core habitat areas were relatively small. Given the threat posed by vessel collisions, a coordinated, multi-national approach to collision mitigation is needed within priority whale shark habitats to ensure collision protection for the species.

Impact of disturbance on common scoter carrying capacity based on an energetic model

Shallow coastal zones are intensely used by humans but simultaneously are biodiversity hotspots, with a crucial role in the life cycle of many marine species. The competition for food or space between humans and protected wildlife intensifies under pressure of an increased need for marine resources for human consumption. For successful management it is important to establish the key components driving such conflicts of interest. Here we focus on the protected common scoter (Melanitta nigra), a sea duck wintering in coastal habitats that are rich in food, but also among the most disturbed marine systems worldwide. Due to the scoters' shyness disturbance impacts the birds' ability to forage and poses a conflict for balancing bird conservation and economics, including a fishery on its main bivalve prey Spisula subtruncata. In this study, we use an energy budget model to quantify the consequences of depth, currents and disturbance on scoter energetics and carrying capacity. Energetics were described using physical parameters and field data on food availability and disturbance. Results reveal non-linear relationships and a threshold value for when a scoter can no longer maintain its energy balance. This is caused by limited foraging time, rather than food availability. From a conservation perspective, this implies that a precautionary principle should be used, because there will be no warning when an area becomes unsuitable. In addition, the model was applied to study the effects of disturbance from different kinds of shipping in a coastal area of the North Sea, north of The Netherlands. Cargo shipping has the largest impact on the carrying capacity, where there is spatial overlap of prey and an intensively used shipping lane. In other prey distribution situations shrimp vessels may cause most disturbance. Spisula-Ensis fisheries did not limit the potential carrying capacity due to the limited catches and number of fishing trips. Scoter protection should be aimed at flexible spatial management and on only those vessel types above a Spisula bed with a large number of trips, and above all should work from a precautionary principle given the critical thresholds for scoter presence.

Modelling parasite impacts of aquaculture on wild fish: The case of the salmon louse (Lepeophtheirus salmonis) on out-migrating wild Atlantic salmon (Salmo salar) smolt

For effective wild salmon (Salmo salar) conservation in areas where aquaculture of salmon is practiced it is necessary to identify where the key parasite, the salmon louse (Lepeophtheirus salmonis), will have an impact on these wild salmon. A simple modelling structure is implemented in a sample system in Scotland for assessing interaction between wild salmon and salmon lice from salmon farms. The model is demonstrated for case studies of smolt sizes and migration routes through salmon lice concentration fields derived for average farm loads from 2018 to 2020. Lice modelling describes production and distribution of lice, infection rates on hosts and biological development of lice. The modelling framework allows explicit assessment of the relationships between lice production, lice concentration and impact on hosts as they grow and migrate. Lice distribution in the environment is determined using a kernel model, which summarises mixing in a complex hydrodynamic system. Smolt modelling describes their initial size, growth and migration pathways. This is illustrated for a set of parameter values applied to 10 cm, 12.5 cm and 15 cm salmon smolts. We found that salmon lice impact depends on initial size of host, smaller smolts will be more susceptible, while larger smolts are less impacted by a given number of lice encounters and migrate more rapidly. This modelling framework can be adapted to allow evaluation of threshold concentrations of lice in the water that should not be exceeded to avoid impacts on smolt populations.

Space and social distancing in managing and preventing COVID-19 community spread: An overview

The spread of COVID-19 at a large scale and at a rapid pace indicates the lack of social distancing measures at multiple levels. The individuals are not to be blamed, nor should we assume the early measures were ineffective or not implemented. It is all down to the multiplicity of transmission factors that made the situation more complicated than initially anticipated. Therefore, in facing the COVID-19 pandemic, this overview paper discusses the importance of space in social distancing measures. The methods used to investigate this study are literature review and case study. Many scholarly works have already provided us with evidence-based models that suggest the influential role of social distancing measures in preventing COVID-19 community spread. To further elaborate on this important topic, the aim here is to look at the role of space not only at the individual level but at larger scales of communities, cities, regions, etc. The analysis helps better management of cities during the pandemics such as COVID-19. By reflecting on some of the ongoing research on social distancing, the study concludes with the role of space at multiple scales and how it is central to the practice of social distancing. We need to be more reflective and responsive to achieve earlier control and containment of the disease and the outbreak at the macro level.

A stakeholder-engaged approach to evaluating spawning aggregation management as a strategy for conserving bonefish (Albula vulpes) in Cuba

Animals that congregate in large numbers to reproduce in spatially and temporally distinct locations are particularly susceptible to overexploitation. Many fishes form spawning aggregations that are intentionally targeted given ease of capture. Bonefish (Albula spp.) species aggregate to spawn and are culturally and economically important, but generally lack management such as spawning area protections to ensure that fisheries are sustainable. Here, we use Cuba as a case study to inform the development and refinement of management strategies for bonefish. Recommendations for the management of bonefish pre-spawning aggregations were based on international experiences, which have been adapted to the Cuban context from results of surveys and interviews with Cuban fisheries professionals and fishing guides. The achievability and feasibility of recommendations were further reviewed by additional experts in the field of fisheries, management and Cuban policy. The process revealed extensive data-limitations for bonefish fisheries and underscored the importance of including fishing guides, local ecological knowledge and the context of marine protected areas in Cuba for bonefish management. Recommendations include (1) initiating information exchange between Cuban management agencies and third-party institutions related to bonefish management; (2) utilizing local ecological knowledge to gather information, formulate management strategies and enforce regulations; (3) implementing spatial and temporal management measures for bonefish spawning sites; (4) using what is already in place, by protecting spawning sites in the context of existing marine protected areas; (5) collaborating with all stakeholders to manage bonefish spawning sites; and (6) reducing the commercial harvest of the species.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10641-022-01355-0.

Investigating the trade-offs between the supply and demand for ecosystem services for regional spatial management

Understanding the supply and demand characteristics of ecosystem services (ESs) and their trade-offs is the basis for effective ecosystem management and the improvement of human well-being. However, current management practices based on the trade-offs between the supply and demand for ESs remain limited. This study aimed to integrate ES trade-offs into regional spatial management. With Changzhi, China, as the study area, this study evaluated the supply, demand, and trade-offs of food provision, water conservation, soil retention, and carbon sequestration by linking multi-source data and using spatial analysis tools, including the InVEST model, ArcGIS, and GeoDA. Based on the trade-offs and importance of different ecological functions, we constructed an urban spatial management framework and proposed recommendations for optimization in different management zones. The results showed that (1) the supply and demand for multiple ESs exhibited spatial heterogeneity. Except for water conservation, the supply of other ESs met the demand of the city, but there were still obvious deficits in some regions. (2) In terms of the ES supply, there were trade-offs between food production and other ESs, and synergies existed among water conservation, soil retention, and carbon sequestration. In terms of the ES demand, the four ESs exhibited synergistic relationships. In the cluster analysis, ES supply and demand were divided into four ES bundles, respectively. (3) The spatial mismatch of ESs in the sub-watersheds of the study area was obvious. The ESDR coldspots for the four ESs were primarily located in the urban built-up areas in the central and southern regions of the city. The ESDR hotspots of soil retention and carbon sequestration were mainly distributed in the eastern and northwestern regions of Changzhi, which are less urbanized. There were few ESDR hotspots for food production and water conservation. (4) Based on the regional spatial management framework, Changzhi was divided into ten zones, including extremely important, moderately important, important, supply-demand risk management, soil erosion management, and high food production areas. The results and conclusions of this study provide a basis for spatial planning and ecosystem management.

A diagrammatic method for the identification and resolution of urban spatial conflicts

Spatial conflicts are formed in the process of urbanization and become the primary drivers of urban ecological and environmental problems. The defining trait of a spatial conflict is the occupation of ecological or agricultural spaces by construction spaces. This work presents a classification scheme for spatial conflicts in China, including source-area conflicts, corridor conflicts, safety conflicts, and farmland conflicts. Also, it constructs a model for the determination of spatial conflicts and conflict intensity using diagrammatic method. Based on a case study performed using our methods on Shenzhen, we proposed a timeline and policy roadmap for the resolution of spatial conflicts in Shenzhen according to the severity and characteristics of spatial conflicts in the city. The results show that the total spatially conflicted area of Shenzhen is 10.57 km², and the percentage of construction land-use in these areas is 1.37%. The spatial conflicts are mainly source-area or corridor conflicts, and minor conflicts account for approximately 60% of the total conflicted area. Most of the spatial conflicts are either "easy to resolve" or "moderately easy to resolve". Overall, in terms of the severity of spatial conflict, Shenzhen remains at the "stable and under control" level. Considering the primary aim of spatial conflict resolution is to revert built-up lands into urban green spaces, we proposed a timeline for the resolution of spatial conflicts in Shenzhen over the next 15 years, as well as a system of supporting policies. The results of this study shall serve as a guide for the optimization of urban spatial structures and the promotion of sustainable urban development.

Evaluating effects of partial fishing closures on the composition and structure of estuarine fish assemblages

Partial fishing closures are an integral component of contemporary aquatic resource conservation and fisheries management. This study examined whether assemblages of fishes differed between partially closed (PC) estuaries that permit recreational fishing compared to fully fished (FF) estuaries that permit commercial and recreational fisheries. Fish assemblages were quantitatively sampled in a standard and stratified manner using a multimesh gillnet and beam trawl that sampled different ichthyofaunal components in two PC and two FF estuaries across three years, ∼ six to eight years post commercial fishing closure and PC implementation. There was no global support for the hypothesis that assemblages, diversity and numbers of fishes would differ between PC and FF estuaries. Assemblages significantly and consistently differed among individual estuaries regardless of estuary management category. Differences between PC and FF estuaries in terms of numbers of species and individuals were inconsistent across years, with more species (gillnet) and individuals (trawl) occurring in PC estuaries in only one of three years. Only one species (Gerres subfasciatus) was more abundant (gillnet) in the PC category, most likely due to reduced fishery harvests. In contrast, juveniles of three harvested species (G. subfasciatus, Rhabdosargus sarba and Acanthopagrus spp.) occurred in greater numbers (trawl) in FF estuaries, potentially a result of strong recruitment and estuary-specific environmental conditions. This study demonstrated the complexity, and potential scale-dependent ecological and fishery-related constraints, in comparatively examining the effects of different fishery management arrangements on fish assemblages across estuary systems.

The challenge of managing the commercial harvesting of the sea urchin Paracentrotus lividus: advanced approaches are required

Sea urchins act as a keystone herbivore in marine coastal ecosystems, regulating macrophyte density, which offers refuge for multiple species. In the Mediterranean Sea, both the sea urchin Paracentrotus lividus and fish preying on it are highly valuable target species for artisanal fisheries. As a consequence of the interactions between fish, sea urchins and macrophyte, fishing leads to trophic disorders with detrimental consequences for biodiversity and fisheries. In Sardinia (Western Mediterranean Sea), regulations for sea urchin harvesting have been in place since the mid 90s. However, given the important ecological role of P. lividus, the single-species fishery management may fail to take into account important ecosystem interactions. Hence, a deeper understanding of population dynamics, their dependance on environmental constraints and multispecies interactions may help to achieve long-term sustainable use of this resource. This work aims to highlight how sea urchin population structure varies spatially in relation to local environmental constraints and species interactions, with implications for their management. The study area (Sinis Peninsula, West Sardinia, Italy) that includes a Marine Reserve was divided into five sectors. These display combinations of the environmental constraints influencing sea urchin population dynamics, namely type of habitat (calcareous rock, granite, basalt, patchy and continuous meadows of Posidonia oceanica), average bottom current speed and predatory fish abundance. Size-frequency distribution of sea urchins under commercial size (<5 cm diameter size) assessed during the period from 2004 to 2007, before the population collapse in 2010, were compared for sectors and types of habitat. Specific correlations between recruits (0–1 cm diameter size) and bottom current speeds and between middle-sized sea urchins (2–5 cm diameter size) and predatory fish abundance were assessed. Parameters representing habitat spatial configuration (patch density, perimeter-to-area ratio, mean patch size, largest patch index, interspersion/juxtaposition index) were calculated and their influence on sea urchin density assessed. The density of sea urchins under commercial size was significantly higher in calcareous rock and was positively and significantly influenced by the density and average size of the rocky habitat patches. Recruits were significantly abundant in rocky habitats, while they were almost absent in P. oceanica meadows. The density of middle-sized sea urchins was more abundant in calcareous rock than in basalt, granite or P. oceanica. High densities of recruits resulted significantly correlated to low values of average bottom current speed, while a negative trend between the abundance of middle-sized sea urchins and predatory fish was found. Our results point out the need to account for the environmental constraints influencing local sea urchin density in fisheries management.

Integration of biophysical connectivity in the spatial optimization of coastal ecosystem services

Ecological connectivity in coastal oceanic waters is mediated by dispersion of the early life stages of marine organisms and conditions the structure of biological communities and the provision of ecosystem services. Integrated management strategies aimed at ensuring long-term service provision to society do not currently consider the importance of dispersal and larval connectivity. A spatial optimization model is introduced to maximise the potential provision of ecosystem services in coastal areas by accounting for the role of dispersal and larval connectivity. The approach combines a validated coastal circulation model that reproduces realistic patterns of larval transport along the coast, which ultimately conditions the biological connectivity and productivity of an area, with additional spatial layers describing potential ecosystem services. The spatial optimization exercise was tested along the coast of Central Chile, a highly productive area dominated by the Humboldt Current. Results show it is unnecessary to relocate existing management areas, as increasing no-take areas by 10% could maximise ecosystem service provision, while improving the spatial representativeness of protected areas and minimizing social conflicts. The location of protected areas was underrepresented in some sections of the study domain, principally due to the restriction of the model to rocky subtidal habitats. Future model developments should encompass the diversity of coastal ecosystems and human activities to inform integrative spatial management. Nevertheless, the spatial optimization model is innovative not only for its integrated ecosystem perspective, but also because it demonstrates that it is possible to incorporate time-varying biophysical connectivity within the optimization problem, thereby linking the dynamics of exploited populations produced by the spatial management regime.

Landscape context and nutrients modify the effects of coastal urbanisation

Estuaries are focal points for coastal cities worldwide, their habitats frequently transformed into engineered shorelines abutting waters with elevated nutrients in an urbanised landscape. Here we test for relationships between shoreline armouring and nutrients on the diversity and trophic composition of fish assemblages across 22 estuaries in eastern Australia. Urbanisation was associated with fish diversity and abundance, but there were differences in the effects of shoreline armouring and nutrient level on the trophic composition of fish assemblages. Fish diversity and the abundance of most trophic groups, particularly omnivores, zoobenthivores and detritivores, was greatest in highly urban estuaries. We show that estuarine fish assemblages are associated with urbanisation in more nuanced ways than simple habitat transformation would suggest, but this depends on the broader environmental context. Our findings have wider implications for estuarine conservation and restoration, emphasizing that ecological benefits of habitat measures may depend on both landscape attributes and water quality in urban settings.