Microplastic is considered a potential threat to marine life as it is ingested by a wide variety of species. Most studies on microplastic ingestion are short-term investigations and little is currently known about how this potential threat has developed over the last decades where global plastic production has increased exponentially. Here we present the first long-term study on microplastic in the marine environment, covering three decades from 1987 to 2015, based on a unique sample set originally collected and conserved for food web studies. We investigated the microplastic concentration in plankton samples and in digestive tracts of two economically and ecologically important planktivorous forage fish species, Atlantic herring (Clupea harengus) and European sprat (Sprattus sprattus), in the Baltic Sea, an ecosystem which is under high anthropogenic pressure and has undergone considerable changes over the past decades. Surprisingly, neither the concentration of microplastic in the plankton samples nor in the digestive tracts changed significantly over the investigated time period. Average microplastic concentration in the plankton samples was 0.21 ± 0.15 particles m− 3. Of 814 fish examined, 20% contained plastic particles, of which 95% were characterized as microplastic (< 5 mm) and of these 93% were fibres. There were no significant differences in the plastic content between species, locations, or time of day the fish were caught. However, fish size and microplastic in the digestive tracts were positively correlated, and the fish contained more plastic during summer than during spring, which may be explained by increased food uptake with size and seasonal differences in feeding activity. This study highlights that even though microplastic has been present in the Baltic environment and the digestive tracts of fishes for decades, the levels have not changed in this period. This underscores the need for greater understanding of how plastic is cycled through marine ecosystems. The stability of plastic concentration and contamination over time observed here indicates that the type and level of microplastic pollution may be more closely correlated to specific human activities in a region than to global plastic production and utilization as such.
A major objective of marine protected area (MPA) network design is to ensure the persistence of species with diverse life histories and functional traits. Considering how species differ in their propensity to move within and between MPAs is therefore a key consideration for multi-species MPA network design. Here, we propose a conceptual framework to incorporate ecological processes that affect movement at multiple life stages into the MPA network design process. We illustrate how our framework can be implemented using a set of hypothetical species that represent regional trait diversity in coastal British Columbia, Canada. We focused on two ecological processes: (1) dispersal during the larval phase and (2) daily home range movement during the adult phase. To identify functional connectivity patterns, we used a biophysical model to simulate larval dispersal, and then prioritized highly-connected patches using a reserve selection algorithm. To ensure that individual reserves were commensurate with home ranges, we also imposed reserve size constraints. Candidate areas for protection were identified based on multi-species connectivity patterns and home range size constraints. Collectively, this conceptual framework offers a flexible approach to multi-species, cross-life stage conservation planning, which can be further adapted to address complex life histories. As marine conservation efforts around the globe aim to design ecologically connected networks of protected areas, the integration of movement and connectivity data throughout ontogeny will be a key component of effective multi-species MPA network design.
There is a growing realization among conservationists that human behavior is the main driver of all key threats to biodiversity and the environment. This realization has led to an escalation of the efforts to influence human behavior toward the adoption of more sustainable alternatives, more recently through the use of social marketing theory and tools. However, these initiatives have traditionally suffered from a lack of robust impact evaluation, which limits not only accountability but also a practitioner’s ability to learn and improve over time. We evaluated three social marketing campaigns conducted in the Philippines, which aimed at increasing the sustainability of local fisheries. To achieve this, we used the results not only from questionnaire surveys but also from biological and enforcement data. We found that although there is some evidence of impact around human behavior and perceptions of conservation results, those changes did not translate into biological outcomes during the 2-year time frame considered in this evaluation. We discuss many of the barriers to causal inference that still remain, particularly if causal links between outcomes and specific interventions are to be drawn, but also showcase how this current methodology can help us go further than the more basic approaches to impact evaluation commonly used. Lastly, we highlight a number of lessons learned from this experience in seeking a practical, ethical, and effective approach to impact evaluation.
The generally positive relationship between the number of sites a species occupies and its average abundance within those sites provides an important link between population processes occurring at different spatial scales. Although such abundance–occupancy relationships (AORs) have been documented across a very wide range of taxa and in many different environments, little is known of such patterns in Earth's largest ecosystem, the deep sea. Wood falls – derived from natural or anthropogenic inputs of wood into the oceans – constitute an important deep-sea habitat, habouring their own unique communities ultimately entirely dependent on the wood for chemical energy. In this study we take advantage of the unique features of an experimental wood fall deployment to examine AORs for the first time in deep-sea invertebrates. The study design combines advantages of both experimental (tractability, control of key environmental parameters) and observational (natural colonisation by taxonomically diverse communities) studies. We show that the interspecific AOR is strongly positive across the 48 species occurring over 32 wood fall communities. The precise form of the AOR is mediated by both species-level life history (body size) and by the colonisation stage at which communities were harvested, but not by environmental energy (wood fall size). Temporal dynamics within species are also generally consistent with positive intraspecific AORs. This support for positive AORs in the deep sea is an important extension of a macroecological generality into a new environment offering considerable potential for further testing and developing mechanistic macroecological theories.
The speed and scale of human impacts on marine species, such as climate change and exploitation for international markets, coupled with a poor regulatory regime and lack of enforcement, make it especially difficult to protect marine species beyond areas of national jurisdiction. Yet as the number of multilateral treaties continues to grow, the declining state of the world's oceans suggest that these treaties are largely failing to fulfill their missions and achieve meaningful protection. Here, an analysis of all multilateral treaties governing activities related to oceans is provided. A range of issues is examined including efficacy, geographic and taxonomic distribution, and other factors that facilitate or inhibit conservation. Since 1882, 103 countries have signed 265 multilateral treaties related to the management of marine resources. The majority of treaties (51%) deal with fisheries, 30% deal with pollution, 4% marine mammals and 15% deal with other topics. In terms of factors that may predict efficacy, 65% of marine treaties have secretariats, 50% have scientific mandates, and 13% have enforcement mechanisms; only 9% have all three. Given the context of the United Nations General Assembly's new commitment to manage human activity and its impact on common resources on the high seas, it is important to understand the strengths and weaknesses – individually and cumulatively - of existing binding marine agreements.
In the early 1990s, the Northwest Atlantic Ocean underwent a fisheries-driven ecosystem shift. Today, the iconic cod (Gadus morhua) remains at low levels, while Atlantic halibut (Hippoglossus hippoglossus) has been increasing since the mid-2000s, concomitant with increasing interest from the fishing industry. Currently, our knowledge about halibut ecology is limited, and the lack of recovery in other collapsed groundfish populations has highlighted the danger of overfishing local concentrations. Here, we apply a Bayesian hierarchical spatiotemporal approach to model the spatial structure of juvenile Atlantic halibut over 36 years and three fisheries management regimes using three model parameters to characterize the resulting spatiotemporal abundance structure: persistence (similarity of spatial structure over time), connectivity (coherence of temporal pattern over space), and spatial variance (variation across the seascape). Two areas of high juvenile abundance persisted through three decades whereas two in the northeast are now diminished, despite the increased abundance and landings throughout the management units. The persistent areas overlap with full and seasonal area closures, which may act as refuges from fishing. Connectivity was estimated to be 250 km, an order of magnitude less than the distance assumed by the definition of the Canadian management units (~2,000 km). The underlying question of whether there are distinct populations within the southern stock unit cannot be answered with this model, but the smaller ~250 km scale of coherent temporal patterns suggests more complex population structure than previously thought, which should be taken into consideration by fishery management.
The drivers behind microplastic (up to 5 mm in diameter) consumption by animals are uncertain and impacts on foundational species are poorly understood. We investigated consumption of weathered, unfouled, biofouled, pre-production and microbe-free National Institute of Standards plastic by a scleractinian coral that relies on chemosensory cues for feeding. Experiment one found that corals ingested many plastic types while mostly ignoring organic-free sand, suggesting that plastic contains phagostimulents. Experiment two found that corals ingested more plastic that wasn't covered in a microbial biofilm than plastics that were biofilmed. Additionally, corals retained ~ 8% of ingested plastic for 24 h or more and retained particles appeared stuck in corals, with consequences for energetics, pollutant toxicity and trophic transfer. The potential for chemoreception to drive plastic consumption in marine taxa has implications for conservation.
Over the last decade, extreme weather and fire events have cost the federal government over $350 billion, according to the Office of Management and Budget. These costs will likely rise as the climate changes, according to the U.S. Global Change Research Program. In February 2013, GAO included Limiting the Federal Government’s Fiscal Exposure by Better Managing Climate Change Risks on its High-Risk List.
GAO was asked to review the potential economic effects of climate change and risks to the federal government. This report examines (1) methods used to estimate the potential economic effects of climate change in the United States, (2) what is known about these effects, and (3) the extent to which information about these effects could inform efforts to manage climate risks across the federal government. GAO reviewed 2 national-scale studies available and 28 other studies; interviewed 26 experts knowledgeable about the strengths and limitations of the studies; compared federal efforts to manage climate risks with leading practices for risk management and economic analysis; and obtained expert views.
Small-scale fisheries are undeniably important for livelihoods, food security and income around the globe. However, they face major challenges, including global market and demographic shifts, policy changes and climate variations that may threaten the wellbeing, health and safety of fishing communities. Over the years, various forms of spatial management have been implemented in small-scale fisheries as a potential solution to problems afflicting these systems. The benefits of such approaches can be numerous for both ecosystems and coastal communities. In addition to the persistent challenges influencing small-scale fisheries practices, the emerging effects of climate change pose serious risks to coastal ecosystems and fishing communities, especially in low-lying islands. Despite a growing recognition of both the benefits of spatial management and the adverse effects of climate change on small-scale fisheries, integration of these concepts in a consistent and comprehensive way has not yet occurred. Spatial management has the potential to foster small-scale fisheries adaptation to climate change, however, in the face of such a global and transboundary phenomenon, management strategies will need to be carefully designed and implemented. First, key considerations for climate-informed spatial management in small-scale fisheries were identified. Second, these key considerations were illustrated in two selected case studies in Pacific Island countries and territories (i.e. Fiji and Papua New Guinea). Finally, the challenges associated with spatial management in a changing climate are discussed and ways forward for advancing this type of management as a climate adaptation approach for small-scale fisheries in the Pacific and beyond are proposed.
Effective ecological indicators (EI) should reflect changes to ecosystem status in a timely manner to guide fishery management; however, the robustness of EIs in the face of sampling uncertainty is not well understood and sampling errors may result in delayed or even unhelpful actions for management. In this study, we use a size-spectrum model to evaluate the effectiveness of EIs in detecting fishery-induced ecosystem changes given various levels of sampling uncertainty. We demonstrate that there is a time-lag exists between changes in fishing pressure and EIs response. The selectivity of survey gears can strongly determine the level of EI responses within certain size ranges. EIs may lost statistical power once sampling errors exceed a certain level, implying that several decades of monitoring data may be needed to be sure of detecting even a large change. Multivariate methods can strengthen the statistical powers of EIs, but only when the level of sampling noises is low. This study suggests the need for considering the impact of sampling uncertainty on the use of ecological indicators in fisheries management.