In the face of growing human impacts on ecosystems, scientists and managers recognize the need to better understand thresholds and non-linear dynamics in ecological systems to help set management targets. However, our understanding of the factors that drive threshold dynamics, and when and how rapidly thresholds will be crossed is currently limited in many systems. In spite of these limitations, there are approaches available to practitioners today—including ecosystem monitoring, statistical methods to identify thresholds and indicators, and threshold-based adaptive management—that can be used to help avoid reaching ecological thresholds or restore systems that have crossed them. We briefly review the current state of knowledge and then use real-world examples to demonstrate how resource managers can use available approaches to avoid crossing ecological thresholds. We also highlight new tools and indicators being developed that have the potential to enhance our ability to detect change, predict when a system is approaching an ecological threshold, or restore systems that have already crossed a tipping point.
Canada’s constitution grants indigenous people priority access to marine resources, yet indigenous, commercial and recreational fishers target the same species. Avoiding conflict between different users, therefore, requires evidence-based policies that manage fisheries for conservation while respecting indigenous rights. From 2006 to 2015, Canada’s Conservative government demoted the role of science in resource management, stifling research by federal agencies like Fisheries and Oceans Canada. To address ensuing data gaps, during 2014–2015 the Heiltsuk, Kitasoo/Xai’Xais, Nuxalk, and Wuikinuxv First Nations conducted coordinated research on Dungeness crab (Cancer magister), a culturally-significant resource. These indigenous groups are experiencing declining catch rates of Dungeness crab and postulate that commercial and recreational fisheries are primary causes of local declines. Accordingly, they applied indigenous laws and declared spatial fishery closures for commercial and recreational fishers at 10 sites (closed) while allowing exploitation by all users to continue at 10 other sites (open). Sampling occurred repeatedly over time and analyses compared temporal trends in population characteristics between closed and open sites. Results were consistent with the hypothesis that fisheries decrease the abundance and size of exploited species, but spatial protection can reverse these effects. The body size and catch-per-unit effort of legal-sized males increased over time at closed sites but declined at open sites. Importantly, fishery status did not affect temporal changes in the relative abundance of unfished classes of crab–sublegal males and females–which is logically consistent with the hypothesis. Our study demonstrates that indigenous governance can create spatial closures for conservation and research when Canada’s government fails to do so. Long-term solutions, however, require collaboration in research and management between federal and indigenous governments. Towards that end, Canada’s newly elected Liberal government has begun to restore federal science and to address indigenous rights, thereby enhancing the possibility of such collaboration.
Recent international initiatives have promoted a number of different approaches to identify marine Important Bird and biodiversity Areas (IBAs), which are important areas for foraging, migrating or over-wintering seabirds. The ‘Foraging Radius Approach’ is one of these and uses known foraging range and habitat preferences to predict the size and location of foraging areas around breeding colonies. Here we assess the performance of the Foraging Radius Approach using GPS tracking data from six seabird species with a variety of foraging modes. For each species we compared the population home-range areas of our six study species with the home-range areas defined using the Foraging Radius Approach. We also assessed whether basic information on depth preferences from tracking data could improve these home-range area estimates. Foraging Radius Approach home-range areas based on maximum foraging radii encompassed the entire population home-range of five out of six of our study species but overestimated the size of the population home-range area in every case. The mean maximum foraging radius overestimated the population home-range areas by a factor of 4–14 for five of the six species whilst the mean foraging radius overestimated the population home-range area for half of the species and underestimated for the rest. In the absence of other data, the Foraging Radius Approach appears to provide a reasonable basis for preliminary marine IBA identification. We suggest that using the mean value of all previously reported maximum foraging radii, informed by basic depth preferences provides the most appropriate prediction, balancing the needs of seabirds with efficient use of marine space.
One key approach for studying emerging technologies in the field of sustainability transitions is that of technological innovation systems (TIS). While most TIS studies aim at deriving policy recommendations – typically by identifying system barriers – the actual role of these proposed policies in the TIS is rarely looked at. In addition, often single policy instruments instead of more encompassing policy mixes are considered. We address these shortcomings by applying a more comprehensive policy mix concept within the TIS approach. In doing so we analyze interdependencies between the policy mix and the TIS by shedding light on the role of the policy mix for TIS functioning and performance as well as how TIS developments influence the evolution of the policy mix. We explore these interdependencies for the case of offshore wind in Germany, using data from event history analysis and expert interviews. We find highly dynamic interdependencies with reoccurring patterns of systemic problems and adjustments of the policy mix, which are fuelled by high policy mix credibility and supportive actors. Our study constitutes a first step incorporating the policy mix concept into the TIS approach, thereby enabling a better understanding of real dynamics occurring in TIS.
Assigning uncertainty to ocean-color satellite products is a requirement to allow informed use of these data. Here, uncertainty estimates are derived using the comparison on a 12th-degree grid of coincident daily records of the remote-sensing reflectance RRSobtained with the same processing chain from three satellite missions, MERIS, MODIS and SeaWiFS. The approach is spatially resolved and produces σ, the part of the RRSuncertainty budget associated with random effects. The global average of σ decreases with wavelength from approximately 0.7–0.9 10− 3 sr− 1 at 412 nm to 0.05–0.1 10− 3 sr− 1at the red band, with uncertainties on σ evaluated as 20–30% between 412 and 555 nm, and 30–40% at 670 nm. The distribution of σ shows a restricted spatial variability and small variations with season, which makes the multi-annual global distribution of σ an estimate applicable to all retrievals of the considered missions. The comparison of σ with other uncertainty estimates derived from field data or with the support of algorithms provides a consistent picture. When translated in relative terms, and assuming a relatively low bias, the distribution of σ suggests that the objective of a 5% uncertainty is fulfilled between 412 and 490 nm for oligotrophic waters (chlorophyll-a concentration below 0.1 mg m− 3). This study also provides comparison statistics. Spectrally, the mean absolute relative difference between RRS from different missions shows a characteristic U-shape with both ends at blue and red wavelengths inversely related to the amplitude of RRS. On average and for the considered data sets, SeaWiFS RRS tend to be slightly higher than MODIS RRS, which in turn appear higher than MERIS RRS. Biases between mission-specific RRS may exhibit a seasonal dependence, particularly in the subtropical belt.
The paper analyses the possibility of using the concept of marine ecosystem services to fuel public debate on the evolutionary resilience of land-sea interface regions. It is based on the experience of the interdisciplinary ARCH project-Architecture and roadmap to manage multiple pressures on lagoons (financed by the Seventh Framework Programme of the EU) that researched the development of selected European regions located around estuaries, fjords, and lagoons. The ARCH project aimed at elaborating interdisciplinary management plans for ten land-sea interface regions in the EU. Marine ecosystem services were used in this process and proved their usefulness as a spanning object bringing together different types of interests, expertise, and knowledge in a holistic way. The paper presents different ways of handling marine ecosystem services as a trigger for public debate on resilience in land-sea interface regions. It analyses the strong and weak points of the concept of ecosystem services to this end and suggests some key preconditions for the more conscious, effective use of the concept in daily decision-making processes in land-sea complex social-ecological systems.
Developing networks of no-take marine reserves is often hindered by uncertainty in the extent to which local marine populations are connected to one another through larval dispersal and recruitment (connectivity). While patterns of connectivity can be predicted by larval dispersal models and validated by empirical methods, biogeographic approaches have rarely been used to investigate connectivity at spatial scales relevant to reserve networks (10's–100's of km). Here, species assemblage patterns in coral reef fish were used together with an individual-based model of dispersal of reef fish larvae to infer patterns of connectivity in a ∼300 km wide region in the Philippines that included the Bohol Sea and adjacent bodies of water. A dominant current flows through the study region, which may facilitate connectivity among >100 no-take reserves. Connectivity was first investigated by analysing data on the presence/absence of 216 species of reef fish and habitat variables across 61 sites. Hierarchical clustering of sites reflecting species assemblage patterns distinguished a major group of sites in the Bohol Sea (Bray–Curtis similarity >70%) from sites situated in adjacent bodies of water (bays, channels between islands and a local sea). The grouping of sites could be partly explained by a combination of degree of embayment, % cover of sand and % cover of rubble (Spearman rank correlation, ρw = 0.42). The individual-based model simulated dispersal of reef fish larvae monthly for three consecutive years in the region. The results of simulations, using a range of pelagic larval durations (15–45 days), were consistent with the species assemblage patterns. Sites in the model that showed strongest potential connectivity corresponded to the majority of sites that comprised the Bohol Sea group suggested by hierarchical clustering. Most sites in the model that exhibited weak connectivity were groups of sites which had fish assemblages that were least similar to those in the Bohol Sea group. Concurrent findings from the two approaches suggest a strong influence of local oceanography and geography on broad spatial patterns of connectivity. The predictions can be used as an initial basis to organise existing reserves to form ecologically meaningful networks. This study showed that species assemblage patterns could be a viable supplementary indicator of connectivity if used together with predictions from a larval dispersal model and if the potential effect of habitat on the structuring of species assemblages is taken into consideration.
In association to the shipping industry there is a broad infrastructure that is connected with multiple activities, e.g., transportation, building and recycling. This infrastructure services the industry, for example ports, and its connected transport network, fairways and canals. The infrastructure activities also entail various environmental issues, such as land use, air emissions, noise, erosion and increased water turbidity. From an environmental perspective, ships have different impacts during the various phases of their lifetimes. Building ships is a highly energy demanding process, and various environmental issues are connected to ship yards. Moreover, when ships are scrapped, the workers typically work under very crude conditions, and often no environmental concern is exercised. To facilitate the effective use of ocean near-shore areas and avoid conflicts among stakeholders, marine spatial planning (MSP) can be applied. Marine spatial planning is a process that views a system and its potential usages from both spatial and temporal perspectives and can facilitate the implementation of ecosystem-based management plans, avoiding conflicts and creating opportunities between various actors in the area. This concept is now being introduced in many countries. Shipwrecks represent a hidden problem that must be addressed. Several thousand shipwrecks litter the ocean floor, containing massive amounts of oil and other toxic chemicals.
Habitat suitability (HS) of target species is assessed in the coastal region of Seno de Corcubión, including Os Miñarzos Marine Protected Area (MPA) in west Galicia, NW of Spain. Current MPA was outlined using local environmental knowledge (LEK). Our objective is to test whether maximization of HS of 12 species would select the same MPA as fishers' LEK. A detailed capture database and 13 layers summarizing ecogeographic variables (derived from bathymetry, satellite data and sea bottom classification map) have been used and several Ecological Niche Factor Analysis (ENFA) Species Distribution Models (SDM) have been tested to find the best HS prediction (according to a nonparametric index due to Boyce). Our SDM results show that the LEK defined MPA (comprising 20% of the total area) is over 70% more suitable than the rest of the region for all species but one (European seabass, only 40%). We conclude that stakeholders LEK methodology correctly identifies local species habitats, and that SDM, and in particular ENFA models, can be used to validate and keep track of the MPA boundaries.
Surface drifters and virtual particles are used to investigate transport between seven coastal regions in the central and southern Adriatic Sea to estimate the degree to which these regions function as a network. Alongshore coastal currents and cyclonic gyres are the primary circulation features that connected regions in the Adriatic Sea. The historical drifter observations span 25 years and, thus, provide estimates of transport between regions realized by the mean surface circulation. The virtual particle trajectories and a dedicated drifter experiment show that southeasterly Sirocco winds can drive eastward cross-Adriatic transport from the Italian coast near the Gargano Promontory to the Dalmatian Islands in Croatia. Southeasterly winds disrupt alongshore transport on the west coast. Northwesterly Mistral winds enhanced east-to-west transport and resulted in stronger southeastward coastal currents in the western Adriatic current (WAC) and export to the northern Ionian Sea. The central Italian regions showed strong connections from north to south, likely realized by alongshore transport in the WAC. Alongshore, downstream transport was weaker on the east coast, likely due to the more complex topography introduced by the Dalmatian Islands of Croatia. Cross-Adriatic connection percentages were higher for east-to-west transport. Cross-Adriatic transport, in general, occurred via the cyclonic sub-gyres, with westward (eastward) transport observed in the northern (southern) arms of the central and southern gyres.