Pesticide impacts through aquatic food webs Jensen, Olaf P.
Science (American Association for the Advancement of Science),
11/2019, Volume:
366, Issue:
6465
Journal Article
Peer reviewed
Effects of neonicotinoid insecticides ricochet all the way to fisheries yields
Testing chemicals for toxicity is straightforward, but detecting their effects at the population, community, or ...ecosystem level is exceedingly difficult. As one moves to higher levels of ecological organization, the number of confounding factors and compensatory mechanisms increases (
1
). Standardized, laboratory studies of pesticides, required by regulatory agencies, typically focus on the short-term effects of acute exposure to individual model organisms with the results scaled up mathematically to estimate long-term and indirect effects. However, long-term and ecosystem-scale ecological studies frequently show surprises and emergent phenomena that couldn't be predicted by extrapolating from results at smaller temporal, spatial, and organizational scales (
2
). To understand the long-term ecosystem impacts of contaminants, one must study entire ecosystems for a long time. On page 620 of this issue, Yamamuro
et al.
(
3
) have done just this, demonstrating that neonicotinoid pesticides can affect entire food webs. Much of what we know about indirect food web impacts of contaminants comes from studies of oil spills. However, even oil spills that release millions of barrels of crude oil can have weak or undetectable effects at the population or community level. The Deepwater Horizon spill—the largest in United States history—is a good example. Extensive studies of nearshore fish populations following the spill have found little evidence of declines (
1
,
4
), despite known toxicity and exposure (
5
). Pesticides present a challenge similar to that of oil spills, but a different kind of exposure: a continued “press” disturbance as they are repeatedly added to the environment rather than the discrete “pulse” disturbance of a major oil spill.
Climate change is altering habitats for marine fishes and invertebrates, but the net effect of these changes on potential food production is unknown. We used temperature-dependent population models ...to measure the influence of warming on the productivity of 235 populations of 124 species in 38 ecoregions. Some populations responded significantly positively (
= 9 populations) and others responded significantly negatively (
= 19 populations) to warming, with the direction and magnitude of the response explained by ecoregion, taxonomy, life history, and exploitation history. Hindcasts indicate that the maximum sustainable yield of the evaluated populations decreased by 4.1% from 1930 to 2010, with five ecoregions experiencing losses of 15 to 35%. Outcomes of fisheries management-including long-term food provisioning-will be improved by accounting for changing productivity in a warmer ocean.
The changing story of seafood Jensen, Olaf P
Science (American Association for the Advancement of Science),
05/2022, Volume:
376, Issue:
6593
Journal Article
Peer reviewed
New technology, new markets, and better policy are improving fisheries and aquaculture
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•We quantified pelagic microplastic pollution in Lake Hovsgol, Mongolia.•Lake Hovsgol is more polluted with microplastics than Lakes Huron and Superior.•Microplastics came from ...consumer goods; no microbeads/few pellets were observed.•Microplastics were sourced from population centers and distributed by the winds.•Without waste management, even small populations can heavily pollute large lakes.
Despite the large and growing literature on microplastics in the ocean, little information exists on microplastics in freshwater systems. This study is the first to evaluate the abundance, distribution, and composition of pelagic microplastic pollution in a large, remote, mountain lake. We quantified pelagic microplastics and shoreline anthropogenic debris in Lake Hovsgol, Mongolia. With an average microplastic density of 20,264 particles km−2, Lake Hovsgol is more heavily polluted with microplastics than the more developed Lakes Huron and Superior in the Laurentian Great Lakes. Fragments and films were the most abundant microplastic types; no plastic microbeads and few pellets were observed. Household plastics dominated the shoreline debris and were comprised largely of plastic bottles, fishing gear, and bags. Microplastic density decreased with distance from the southwestern shore, the most populated and accessible section of the park, and was distributed by the prevailing winds. These results demonstrate that without proper waste management, low-density populations can heavily pollute freshwater systems with consumer plastics.
Marine fish stocks are an important part of the world food system and are particularly important for many of the poorest people of the world. Most existing analyses suggest overfishing is increasing, ...and there is widespread concern that fish stocks are decreasing throughout most of the world. We assembled trends in abundance and harvest rate of stocks that are scientifically assessed, constituting half of the reported global marine fish catch. For these stocks, on average, abundance is increasing and is at proposed target levels. Compared with regions that are intensively managed, regions with less-developed fisheries management have, on average, 3-fold greater harvest rates and half the abundance as assessed stocks. Available evidence suggests that the regions without assessments of abundance have little fisheries management, and stocks are in poor shape. Increased application of area-appropriate fisheries science recommendations and management tools are still needed for sustaining fisheries in places where they are lacking.
Ecosystem-based approaches, including integrated ecosystem assessments, are a popular methodology being used to holistically address management issues in social–ecological systems worldwide. In this ...study we utilized fuzzy logic cognitive mapping to develop conceptual models of a complex estuarine system among four stakeholder groups. The average number of categories in an individual map was not significantly different among groups, and there were no significant differences between the groups in the average complexity or density indices of the individual maps. When ordered by their complexity scores, eight categories contributed to the top four rankings of the stakeholder groups, with six of the categories shared by at least half of the groups. While non-metric multidimensional scaling (nMDS) analysis displayed a high degree of overlap between the individual models across groups, there was also diversity within each stakeholder group. These findings suggest that while all of the stakeholders interviewed perceive the subject ecosystem as a complex series of social and ecological interconnections, there are a core set of components that are present in most of the groups' models that are crucial in managing the system towards some desired outcome. However, the variability in the connections between these core components and the rest of the categories influences the exact nature of these outcomes. Understanding the reasons behind these differences will be critical to developing a shared conceptual model that will be acceptable to all stakeholder groups and can serve as the basis for an integrated ecosystem assessment.
•We created conceptual models of an estuarine system for four stakeholder groups.•Estuaries are perceived as a complex series of social and ecological interconnections.•There are a core set of key components present across the groups' models.•Understanding differences in connections between models is critical for management.•FCM based models can serve as the basis for integrated ecosystem assessments.
Commercial fisheries globally experienced numerous and significant perturbations during the early months of the COVID-19 pandemic, affecting the livelihoods of millions of fishers worldwide. In the ...Northeast United States, fishers grappled with low prices and disruptions to export and domestic markets, leaving many tied to the dock, while others found ways to adapt to the changing circumstances brought about by the pandemic. This paper investigates the short-term impacts of the early months of the COVID-19 pandemic (March-June 2020) on commercial fishers in the Northeast U.S. to understand the effects of the pandemic on participation in the fishery and fishers' economic outcomes, using data collected from an online survey of 258 Northeast U.S. commercial fishers. This research also assesses characteristics of those fishers who continued fishing and their adaptive strategies to the changing circumstances. Analysis of survey responses found the majority of fishers continued fishing during the early months of the pandemic, while a significant number had stopped fishing. Nearly all reported a loss of income, largely driven by disruptions of export markets, the loss of restaurant sales, and a resulting decline in seafood prices. Landings data demonstrate that while fishing pressure in 2020 was reduced for some species, it remained on track with previous years for others. Fishers reported engaging in a number of adaptation strategies, including direct sales of seafood, switching species, and supplementing their income with government payments or other sources of income. Many fishers who had stopped fishing indicated plans to return, suggesting refraining from fishing as a short-term adaptation strategy, rather than a plan to permanently stop fishing. Despite economic losses, fishers in the Northeast U.S. demonstrated resilience in the face of the pandemic by continuing to fish and implementing other adaptation strategies rather than switching to other livelihoods.
Marine protected areas (MPAs) are increasingly being used globally to conserve marine resources. However, whether many MPAs are being effectively and equitably managed, and how MPA management ...influences substantive outcomes remain unknown. We developed a global database of management and fish population data (433 and 218 MPAs, respectively) to assess: MPA management processes; the effects of MPAs on fish populations; and relationships between management processes and ecological effects. Here we report that many MPAs failed to meet thresholds for effective and equitable management processes, with widespread shortfalls in staff and financial resources. Although 71% of MPAs positively influenced fish populations, these conservation impacts were highly variable. Staff and budget capacity were the strongest predictors of conservation impact: MPAs with adequate staff capacity had ecological effects 2.9 times greater than MPAs with inadequate capacity. Thus, continued global expansion of MPAs without adequate investment in human and financial capacity is likely to lead to sub-optimal conservation outcomes.
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