While population declines can drive the loss of genetic diversity under some circumstances, it has been unclear whether this loss is a general consequence of overharvest in highly abundant marine ...fishes. We compiled data from 11 049 loci across 140 species and found that allelic richness was lower in overfished populations within 9 of 12 genera and families. A multiple linear regression showed that allelic richness was on average 12% lower (P < 0.0001) in overharvested populations after accounting for the effects of body size, latitude and other factors. Heterozygosity was on average 2% lower (P = 0.030). Simulations confirmed that these patterns are consistent with a recent bottleneck in abundant species and also showed that our analysis likely underestimates the loss of rare alleles by a factor of two or three. This evidence suggests that overharvest drives the decay of genetic diversity across a wide range of marine fishes. Such reductions of genetic diversity in some of the world's most abundant species may lead to a long‐term impact of fishing on their evolutionary potential, particularly if abundance remains low and diversity continues to decay.
Understanding which species and ecosystems will be most severely affected by warming as climate change advances is important for guiding conservation and management. Both marine and terrestrial fauna ...have been affected by warming
but an explicit comparison of physiological sensitivity between the marine and terrestrial realms has been lacking. Assessing how close populations live to their upper thermal limits has been challenging, in part because extreme temperatures frequently drive demographic responses
and yet fauna can use local thermal refugia to avoid extremes
. Here we show that marine ectotherms experience hourly body temperatures that are closer to their upper thermal limits than do terrestrial ectotherms across all latitudes-but that this is the case only if terrestrial species can access thermal refugia. Although not a direct prediction of population decline, this thermal safety margin provides an index of the physiological stress caused by warming. On land, the smallest thermal safety margins were found for species at mid-latitudes where the hottest hourly body temperatures occurred; by contrast, the marine species with the smallest thermal safety margins were found near the equator. We also found that local extirpations related to warming have been twice as common in the ocean as on land, which is consistent with the smaller thermal safety margins at sea. Our results suggest that different processes will exacerbate thermal vulnerability across these two realms. Higher sensitivities to warming and faster rates of colonization in the marine realm suggest that extirpations will be more frequent and species turnover faster in the ocean. By contrast, terrestrial species appear to be more vulnerable to loss of access to thermal refugia, which would make habitat fragmentation and changes in land use critical drivers of species loss on land.
Marine Taxa Track Local Climate Velocities Pinsky, Malin L.; Worm, Boris; Fogarty, Michael J. ...
Science (American Association for the Advancement of Science),
09/2013, Letnik:
341, Številka:
6151
Journal Article
Recenzirano
Organisms are expected to adapt or move in response to climate change, but observed distribution shifts span a wide range of directions and rates. Explanations often emphasize biological distinctions ...among species, but general mechanisms have been elusive. We tested an alternative hypothesis: that differences in climate velocity—the rate and direction that climate shifts across the landscape—can explain observed species shifts. We compiled a database of coastal surveys around North America from 1968 to 2011, sampling 128 million individuals across 360 marine taxa. Climate velocity explained the magnitude and direction of shifts in latitude and depth much more effectively than did species characteristics. Our results demonstrate that marine species shift at different rates and directions because they closely track the complex mosaic of local climate velocities.
The geographic distributions of marine species are changing rapidly, with leading range edges following climate poleward, deeper, and in other directions and trailing range edges often contracting in ...similar directions. These shifts have their roots in fine-scale interactions between organisms and their environment-including mosaics and gradients of temperature and oxygen-mediated by physiology, behavior, evolution, dispersal, and species interactions. These shifts reassemble food webs and can have dramatic consequences. Compared with species on land, marine species are more sensitive to changing climate but have a greater capacity for colonization. These differences suggest that species cope with climate change at different spatial scales in the two realms and that range shifts across wide spatial scales are a key mechanism at sea. Additional research is needed to understand how processes interact to promote or constrain range shifts, how the dominant responses vary among species, and how the emergent communities of the future ocean will function.
Recent shifts in the geographic distribution of marine species have been linked to shifts in preferred thermal habitats. These shifts in distribution have already posed challenges for living marine ...resource management, and there is a strong need for projections of how species might be impacted by future changes in ocean temperatures during the 21st century. We modeled thermal habitat for 686 marine species in the Atlantic and Pacific oceans using long-term ecological survey data from the North American continental shelves. These habitat models were coupled to output from sixteen general circulation models that were run under high (RCP 8.5) and low (RCP 2.6) future greenhouse gas emission scenarios over the 21st century to produce 32 possible future outcomes for each species. The models generally agreed on the magnitude and direction of future shifts for some species (448 or 429 under RCP 8.5 and RCP 2.6, respectively), but strongly disagreed for other species (116 or 120 respectively). This allowed us to identify species with more or less robust predictions. Future shifts in species distributions were generally poleward and followed the coastline, but also varied among regions and species. Species from the U.S. and Canadian west coast including the Gulf of Alaska had the highest projected magnitude shifts in distribution, and many species shifted more than 1000 km under the high greenhouse gas emissions scenario. Following a strong mitigation scenario consistent with the Paris Agreement would likely produce substantially smaller shifts and less disruption to marine management efforts. Our projections offer an important tool for identifying species, fisheries, and management efforts that are particularly vulnerable to climate change impacts.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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.
Preparing ocean governance for species on the move Pinsky, Malin L; Reygondeau, Gabriel; Caddell, Richard ...
Science (American Association for the Advancement of Science),
06/2018, Letnik:
360, Številka:
6394
Journal Article
Recenzirano
Odprti dostop
Policy must anticipate conflict over geographic shifts
The ocean is a critical source of nutrition for billions of people, with potential to yield further food, profits, and employment in the future ...(
1
). But fisheries face a serious new challenge as climate change drives the ocean to conditions not experienced historically. Local, national, regional, and international fisheries are substantially underprepared for geographic shifts in marine animals driven by climate change over the coming decades. Fish and other animals have already shifted into new territory at a rate averaging 70 km per decade (
2
), and these shifts are expected to continue or accelerate (
3
). We show here that many species will likely shift across national and other political boundaries in the coming decades, creating the potential for conflict over newly shared resources.
Species around the world have suffered collapses, and a key question is why some populations are more vulnerable than others. Traditional conservation biology and evidence from terrestrial species ...suggest that slow-growing populations are most at risk, but interactions between climate variability and harvest dynamics may alter or even reverse this pattern. Here, we test this hypothesis globally. We use boosted regression trees to analyse the influences of harvesting, species traits and climate variability on the risk of collapse (decline below a fixed threshold) across 154 marine fish populations around the world. The most important factor explaining collapses was the magnitude of overfishing, while the duration of overfishing best explained long-term depletion. However, fast growth was the next most important risk factor. Fast-growing populations and those in variable environments were especially sensitive to overfishing, and the risk of collapse was more than tripled for fast-growing when compared with slow-growing species that experienced overfishing. We found little evidence that, in the absence of overfishing, climate variability or fast growth rates alone drove population collapse over the last six decades. Expanding efforts to rapidly adjust harvest pressure to account for climate-driven lows in productivity could help to avoid future collapses, particularly among fast-growing species.
Marine defaunation: Animal loss in the global ocean McCauley, Douglas J.; Pinsky, Malin L.; Palumbi, Stephen R. ...
Science (American Association for the Advancement of Science),
01/2015, Letnik:
347, Številka:
6219
Journal Article
Recenzirano
Odprti dostop
Marine defaunation, or human-caused animal loss in the oceans, emerged forcefully only hundreds of years ago, whereas terrestrial defaunation has been occurring far longer. Though humans have caused ...few global marine extinctions, we have profoundly affected marine wildlife, altering the functioning and provisioning of services in every ocean. Current ocean trends, coupled with terrestrial defaunation lessons, suggest that marine defaunation rates will rapidly intensify as human use of the oceans industrializes. Though protected areas are a powerful tool to harness ocean productivity, especially when designed with future climate in mind, additional management strategies will be required. Overall, habitat degradation is likely to intensify as a major driver of marine wildlife loss. Proactive intervention can avert a marine defaunation disaster of the magnitude observed on land.
By 2100, ocean waters are expected to be substantially warmer and more acidic than they are today, with profound effects on coupled social-ecological fisheries systems. Despite broad recognition of ...impacts from both anthropogenic climate change and natural climate variability, incorporating climate and acidification considerations into management approaches has been difficult. However, clear opportunities exist for fostering "climate-ready" fisheries management, as evidenced by emerging research and implementation experiences that we review here. Approaches now exist for integrating climate change and variability into monitoring, vulnerability assessments, stock assessments, spatial management, annual harvest limits, international agreements, and management of emerging fisheries. While uncertainty, limited understanding, and the increased complexity of these new considerations have delayed more widespread implementation to date, these factors do not change the reality of climate change impacts on living marine resources. We conclude that, despite ongoing research needs, fisheries management can substantially expand capacity to respond to a changing climate.
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