Aim
Declining biodiversity across ecosystems and myriad human pressures necessitate high‐level regional assessments for effective management. Evaluation of biodiversity patterns and stressor ...accumulation through beta diversity and cumulative effect analyses are two key methods for management prioritization. This study links these concepts to develop a novel cumulative effect metric based on beta diversity responses.
Location
Fraser River basin, British Columbia, Canada.
Methods
Multi‐Site Generalized Dissimilarity Models were used to evaluate nonlinear relationships between fish species compositional differences (ζn, number of shared species across any number of watersheds compared) and human pressure, environmental, and geospatial differences among all watersheds and within low, mid‐, and high elevation clusters. A cumulative effect metric was calculated as the sum of response values generated by the model for each human pressure variable specific to each watershed, when evaluated for ζ2 (equivalent to pairwise beta diversity). This metric was tested against the local contribution of each watershed to beta diversity to determine whether watersheds with unique communities had low cumulative effects and are, therefore, candidates for conservation and conversely, whether watersheds with non‐distinctive communities had high cumulative effects and warrant restoration. Species contributions to beta diversity were also assessed across the basin.
Results
Zeta diversity across low elevation watersheds indicated stronger filtering by human pressures than mid‐ and high elevation watersheds, which showed more stochastic community assembly. The relative importance and response to human pressures varied based on the diversity component (i.e., total diversity including compositional nestedness vs. turnover) and order of zeta (number of watersheds compared). Cumulative effects were negatively related to community uniqueness, supporting the use of these metrics for developing management priorities.
Main Conclusions
This assessment contributes to biodiversity conservation efforts by identifying important watersheds, species, and human pressures to manage as well as providing a cumulative effect metric directly based on biodiversity responses.
Successful management of imperilled anadromous salmon stocks requires understanding how salmon will respond to a changing climate across their extensive ranges. Though largely unused for anadromous ...salmon to date, environmental niche models (ENMs) can provide a strong foundation for estimating where and how much habitat will likely remain favourable. We applied a comprehensive suite of ENM statistical approaches to five Pacific salmon species, focusing on freshwater spawning and natal rearing habitat as not only critical for population survival, but also highly susceptible to a changing climate. We developed ENMs for spawning ranges across British Columbia (BC), Canada, and western US, and projected future scenarios for BC. Projections indicated net expansion of favourable spawning habitat across species in BC, with the most change occurring by 2060. However, shifts in favourable habitat varied greatly geographically and by species, with notable reductions in coastal and southern interior streams. Our results provide a basis for identifying important changes in spawning and natal rearing habitat conditions to help inform priorities for restoration and protection actions.
We identified emerging scientific, technological, and sociopolitical issues likely to affect how biological invasions are studied and managed over the next two decades. Issues were ranked according ...to their probability of emergence, pervasiveness, potential impact, and novelty. Top-ranked issues include the application of genomic modification tools to control invasions, effects of Arctic globalization on invasion risk in the Northern Hemisphere, commercial use of microbes to facilitate crop production, the emergence of invasive microbial pathogens, and the fate of intercontinental trade agreements. These diverse issues suggest an expanding interdisciplinary role for invasion science in biosecurity and ecosystem management, burgeoning applications of biotechnology in alien species detection and control, and new frontiers in the microbial ecology of invasions.
Expanding transportation networks, technological advances, global environmental change, and geopolitical forces are transforming risks of invasion worldwide.
Genomic modification tools offer novel risks and potential solutions to managing invasions.
Rapid warming and intensified human activities in the Arctic will alter invasion patterns and risks across the Northern Hemisphere.
Anthropogenic stressors promote rapid evolutionary shifts that cause native and alien populations to become invasive.
Microbial ecology is becoming increasingly relevant to understanding and managing invasions.
Derelict fishing gear is a global problem, damaging marine ecosystems via habitat degradation and killing marine life, thereby impacting fisheries. We conducted a global review of reasons for ...commercial gear loss, and used the findings to design a survey focused on coastal British Columbia (BC), Canada. We conducted dockside and on-line surveys of commercial fishers to record their experiences with lost gear across net, line, and trap gear types. The most common reasons for gear loss from the global review were interactions with other fishing vessels and their gear, marine weather, and snagging on submerged features. Survey results of 29 fishers in BC indicated that snagging gear on rough substrate was the most important reason for loss across all gear categories, followed by seafloor type. Other reasons for gear loss varied by net, line, and trap gear type. Understanding reasons for gear loss is important to reduce losses.
•Interactions with other vessels/gear and marine weather lead to global gear loss.•Snagging on rough seafloor was the top gear loss reason in Canada's Pacific.•Fishers in Canada's Pacific made changes to how they fish to prevent gear loss.•Gear maintenance and education can prevent gear loss in Pacific Canada.
Identifying and protecting coastal nursery habitats is imperative as human impacts to these areas accelerate. Nursery habitats support higher juvenile (1) density, (2) growth, or (3) survival ...(hereafter nursery role metrics) than other habitats, resulting in a greater contribution to adult populations. Seagrass habitat is commonly referred to as a nursery, but its contribution to each nursery role metric across geographic regions and in comparison to other nursery habitats (e.g. mangroves, coral reefs, salt marshes) remains unclear. We conducted a global meta-analysis of juvenile fish and macro-invertebrate performance in seagrass relative to other habitats to assess the nursery role metric, geographic region, and taxonomic group for which seagrass is most beneficial. We compiled data from 51 papers, spanning temperate, subtropical, and tropical regions and including unstructured and structured comparative habitats. We found that, overall, seagrass provided better nursery habitat than other habitats, particularly for supporting high juvenile density and growth. Seagrass habitat was generally more beneficial in temperate and subtropical regions than in the tropics, and more important for juvenile invertebrates than for fishes. Seagrass appears to be highly valuable for provision of food, but supplies equivalent or less adequate refuge than other nursery habitats. Management efforts may benefit from prioritizing conservation of seagrass habitats as food sources for juveniles in combination with other structured habitats for refuge in temperate regions; in tropical regions, seagrass may be a less important nursery habitat to target for conservation, though the value of nursery habitats may shift with ongoing climate change.
The global extent of marine protected areas (MPAs) is increasing as nations strive to meet UN conservation targets, yet non-native species (NNS) are a critically overlooked stressor that threatens ...MPA conservation goals. Despite evidence that marine NNS affect protected species and habitats, there is limited understanding of the pervasiveness of this threat and the extent to which resource managers are responding to it. We disseminated a questionnaire targeting MPA practitioners and scientists to determine the overall state of knowledge and perception of NNS in MPAs. We received 151 responses from individuals in 47 countries and territories, including a total of 116 MPAs of which 73 were reported to have NNS present. Although NNS are a prevalent issue in MPAs and are the subject of some monitoring, management, and research, preventative measures are largely absent, so that more focused attention on NNS will be required to achieve conservation goals.
Anthropogenic activities have led to the biotic homogenization of many ecological communities, yet in coastal systems this phenomenon remains understudied. In particular, activities that locally ...affect marine habitat‐forming foundation species may perturb habitat and promote species with generalist, opportunistic traits, in turn affecting spatial patterns of biodiversity. Here, we quantified fish diversity in seagrass communities across 89 sites spanning 6° latitude along the Pacific coast of Canada, to test the hypothesis that anthropogenic disturbances homogenize (i.e., lower beta‐diversity) assemblages within coastal ecosystems. We test for patterns of biotic homogenization at sites within different anthropogenic disturbance categories (low, medium, and high) at two spatial scales (within and across regions) using both abundance‐ and incidence‐based beta‐diversity metrics. Our models provide clear evidence that fish communities in high anthropogenic disturbance seagrass areas are homogenized relative to those in low disturbance areas. These results were consistent across within‐region comparisons using abundance‐ and incidence‐based measures of beta‐diversity, and in across‐region comparisons using incidence‐based measures. Physical and biotic characteristics of seagrass meadows also influenced fish beta‐diversity. Biotic habitat characteristics including seagrass biomass and shoot density were more differentiated among high disturbance sites, potentially indicative of a perturbed environment. Indicator species and trait analyses revealed fishes associated with low disturbance sites had characteristics including stenotopy, lower swimming ability, and egg guarding behavior. Our study is the first to show biotic homogenization of fishes across seagrass meadows within areas of relatively high human impact. These results support the importance of targeting conservation efforts in low anthropogenic disturbance areas across land‐ and seascapes, as well as managing anthropogenic impacts in high activity areas.
We found evidence of biotic homogenization of fish communities in seagrass meadows characterized by high anthropogenic disturbance, both within and across regions spanning the extent of the Pacific coast of Canada. We show that heterogeneity in the biotic characteristics of these more perturbed environments contributes to low beta‐diversity and the dominance of generalist species able to tolerate impacted systems.
Unprecedented rates of introduction and spread of non-native species pose burgeoning challenges to biodiversity, natural resource management, regional economies, and human health. Current biosecurity ...efforts are failing to keep pace with globalization, revealing critical gaps in our understanding and response to invasions. Here, we identify four priority areas to advance invasion science in the face of rapid global environmental change. First, invasion science should strive to develop a more comprehensive framework for predicting how the behavior, abundance, and interspecific interactions of non-native species vary in relation to conditions in receiving environments and how these factors govern the ecological impacts of invasion. A second priority is to understand the potential synergistic effects of multiple co-occurring stressors— particularly involving climate change—on the establishment and impact of non-native species. Climate adaptation and mitigation strategies will need to consider the possible consequences of promoting non-native species, and appropriate management responses to non-native species will need to be developed. The third priority is to address the taxonomic impediment. The ability to detect and evaluate invasion risks is compromised by a growing deficit in taxonomic expertise, which cannot be adequately compensated by new molecular technologies alone. Management of biosecurity risks will become increasingly challenging unless academia, industry, and governments train and employ new personnel in taxonomy and systematics. Fourth, we recommend that internationally cooperative biosecurity strategies consider the bridgehead effects of global dispersal networks, in which organisms tend to invade new regions from locations where they have already established. Cooperation among countries to eradicate or control species established in bridgehead regions should yield greater benefit than independent attempts by individual countries to exclude these species from arriving and establishing.
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