Humans have elevated global extinction rates and thus lowered global scale species richness. However, there is no a priori reason to expect that losses of global species richness should always, or ...even often, trickle down to losses of species richness at regional and local scales, even though this relationship is often assumed. Here, we show that scale can modulate our estimates of species richness change through time in the face of anthropogenic pressures, but not in a unidirectional way. Instead, the magnitude of species richness change through time can increase, decrease, reverse, or be unimodal across spatial scales. Using several case studies, we show different forms of scale‐dependent richness change through time in the face of anthropogenic pressures. For example, Central American corals show a homogenization pattern, where small scale richness is largely unchanged through time, while larger scale richness change is highly negative. Alternatively, birds in North America showed a differentiation effect, where species richness was again largely unchanged through time at small scales, but was more positive at larger scales. Finally, we collated data from a heterogeneous set of studies of different taxa measured through time from sites ranging from small plots to entire continents, and found highly variable patterns that nevertheless imply complex scale‐dependence in several taxa. In summary, understanding how biodiversity is changing in the Anthropocene requires an explicit recognition of the influence of spatial scale, and we conclude with some recommendations for how to better incorporate scale into our estimates of change.
The intensity and frequency of climate-driven disturbances are increasing in coastal marine ecosystems. Understanding the factors that enhance or inhibit ecosystem resilience to climatic disturbance ...is essential. We surveyed 97 experts in six major coastal biogenic ecosystem types to identify “bright spots” of resilience in the face of climate change. We also evaluated literature that was recommended by the experts that addresses the responses of habitat-forming species to climatic disturbance. Resilience was commonly reported in the expert surveys (80% of experts). Resilience was observed in all ecosystem types and at multiple locations worldwide. The experts and literature cited remaining biogenic habitat, recruitment/connectivity, physical setting, and management of local-scale stressors as most important for resilience. These findings suggest that coastal ecosystems may still hold great potential to persist in the face of climate change and that local- to regional-scale management can help buffer global climatic impacts.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Climate change and other anthropogenic drivers of biodiversity change are unequally distributed across the world. Overlap in the distributions of different drivers have important implications for ...biodiversity change attribution and the potential for interactive effects. However, the spatial relationships among different drivers and whether they differ between the terrestrial and marine realm has yet to be examined.
We compiled global gridded datasets on climate change, land‐use, resource exploitation, pollution, alien species potential and human population density. We used multivariate statistics to examine the spatial relationships among the drivers and to characterize the typical combinations of drivers experienced by different regions of the world.
We found stronger positive correlations among drivers in the terrestrial than in the marine realm, leading to areas with high intensities of multiple drivers on land. Climate change tended to be negatively correlated with other drivers in the terrestrial realm (e.g. in the tundra and boreal forest with high climate change but low human use and pollution), whereas the opposite was true in the marine realm (e.g. in the Indo‐Pacific with high climate change and high fishing).
We show that different regions of the world can be defined by Anthropogenic Threat Complexes (ATCs), distinguished by different sets of drivers with varying intensities. We identify 11 ATCs that can be used to test hypotheses about patterns of biodiversity and ecosystem change, especially about the joint effects of multiple drivers.
Our global analysis highlights the broad conservation priorities needed to mitigate the impacts of anthropogenic change, with different priorities emerging on land and in the ocean, and in different parts of the world.
Abstrakt
Der Klimawandel und andere anthropogene Faktoren, die die biologische Vielfalt verändern, betreffen nicht alle Teile der Erde in gleicher Weise. Während unsere Kenntnisse zu jedem einzelnen Gefährdungsfaktor ständig wachsen, ist unser Verständnis zu den räumlichen Beziehungen zwischen den verschiedenen Faktoren und ihr Zusammenwirken noch sehr mangelhaft. Das betrifft z.B. auch die Unterschiede zwischen terrestrischen und marinen Lebensräumen, die sehr unterschiedlichen Bedrohungen ausgesetzt sein können, selbst wenn sie eng benachbart sind.
In der vorliegenden Studie haben wir globale Datensätze über Klimawandel, Landnutzung, Ressourcenausbeutung, Umweltverschmutzung, biologische Invasionen und Bevölkerungsdichte zusammengestellt. Mit Hilfe multivariater Statistiken haben wir die räumlichen Beziehungen zwischen diesen Ursachen des globalen Biodiversitätswandels und deren Kombinationen untersucht, um deren Einfluss auf verschiedene Regionen der Welt zu charakterisieren.
Insbesondere in den terrestrischen Regionen wirken die genannten Gefährdungsfaktoren häufig in der gleichen Richtung, vor allem solche, die zum Teil besonders hohe Belastungen darstellen. Regionen mit stärker ausgeprägtem Klimawandel sind tendenziell solche Gebiete, in denen die Gefährdung durch andere Faktoren eher geringer ist, wie z.B. in der Tundra und im borealen Nadelwald, die stark vom Klimawandel, aber weniger von hoher Nutzungsintensität und Verschmutzung betroffen sind. Dagegen treten in den Meeresregionen gegenteilige Muster auf, wo z.B. im Indopazifik ein sehr ausgeprägter Klimawandel einer hoher Ressourcenausbeutung durch Fischerei zusammenfällt.
Die Regionen der Welt lassen sich in Klassen unterschiedlicher Interaktionen und Intensitäten dieser anthropogenen Gefährungsfaktoren unterteilen. Diese insgesamt 11 verschiedene Faktorenklassen können nun dazu verwendet werden, Auswirkungen auf Biodiversität zu untersuchen und die Gefährdungs‐Hotspots zu identifizieren. Diese Hotspots sind diejenigen großräumigen Meeres‐ und Festlandsregionen, in denen prioritär Naturschutzmaßnahmen angewendet werden müssen, um den Auswirkungen des anthropogenen Biodiversitätswandels entgegenzutreten.
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
The extent to which different grazers are functionally redundant has strong implications for the maintenance of community structure and function. Grazing by red urchins (Strongylocentrotus ...franciscanus) on temperate rocky reefs can initiate a switch from invertebrate or macroalgal dominance to an algal crust state, but can also cause increases in the density of molluscan mesograzers. In this study, we tested the hypothesis that red urchins and lined chitons (Tonicella spp.) are redundant in the maintenance of available space, defined as encrusting algae and bare rock. In a factorial field experiment replicated at three sites, we reduced the densities of urchins and chitons on subtidal rock walls for nine months. The effects of grazers were interpreted in the context of natural temporal variation by monitoring the benthic community one year before, during, and after grazer removal. The removal of each grazer in isolation had no effect on the epilithic community, but the removal of both grazers caused an increase in sessile invertebrates. The increase was due primarily to clonal ascidians, which displayed a large (∼75%) relative increase in response to the removal of both grazers. However, the observed non-additive responses to grazer removal were temporary and smaller than seasonal fluctuations. Our data demonstrate that urchins and chitons can be redundant in the maintenance of available space, and highlight the value of drawing conclusions from experimental manipulations within an extended temporal context.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Anthropogenic environmental change has increased coral reef disturbance regimes in recent decades, altering the structure and function of many coral reefs globally. In this study, we used coral ...community survey data collected from 1996 to 2015 to evaluate reef‐scale coral calcification capacity (CCC) dynamics with respect to recorded pulse disturbances for 121 reef sites in the Main Hawaiian Islands and Mo'orea (French Polynesia) in the Pacific and the Florida Keys Reef Tract and St. John (U.S. Virgin Islands) in the western Atlantic. CCC remained relatively high in the Main Hawaiian Islands in the absence of recorded widespread disturbances; declined and subsequently recovered in Mo'orea following a crown‐of‐thorns sea star outbreak, coral bleaching, and major cyclone; decreased and remained low following coral bleaching in the Florida Keys Reef Tract; and decreased following coral bleaching and disease in St. John. Individual coral taxa have variable calcification rates and susceptibility to disturbances because of their differing life‐history strategies. As a result, temporal changes in CCC in this study were driven by shifts in both overall coral cover and coral community composition. Analysis of our results considering coral life‐history strategies showed that weedy corals generally increased their contributions to CCC over time while the contribution of competitive corals decreased. Shifts in contributions by stress‐tolerant and generalist corals to CCC were more variable across regions. The increasing frequency and intensity of disturbances under 21st century global change therefore has the potential to drive lower and more variable CCC because of the increasing dominance of weedy and some stress‐tolerant corals.
Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity ...within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. Main types of variables included: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. Spatial location and grain: BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2). Time period and grain: BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. Major taxa and level of measurement: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates. Software format:.csv and.SQL.
On Caribbean reefs, a striking trend of the last 25 years has been the decline in cover of the framework-building coral Montastraea annularis, a species that has dominated reefs throughout the region ...for millennia. Clearly, such losses are important ecologically, but to evaluate their significance fully, they need to be placed in the context of the proximal causes and balanced against the potential for gains in cover through growth and recruitment. In this study, a population of M. annularis in St. John, U.S. Virgin Islands, was censused annually from 1988 to 2003 to quantify coral cover and construct a size-based demographic model. The model was developed to explore the mechanisms of change in coral cover and to ascertain likely trajectories for future population growth. Over the study period, the cover of M. annularis declined from 41% in 1988, to 12% by 1999 (a 72% decline) but remained unchanged statistically for the last five years of the study. Between 1988 and 2003, colony abundances declined by 57% (from 47 colonies/m2 to 20 colonies/m2), and the losses were driven mostly by the death and fission of medium to large colonies (i.e., 151 cm2). By 2003, the population had proportionally more small colonies (70% were 50 cm2) and fewer large colonies (3% were >250 cm2) than in 1988 (60% and 6%, respectively), and the changes in population structure had accelerated 14% in terms of the rate of change in population size and the time necessary to attain equilibrium of colony size structure. Importantly, this analysis revealed an ongoing and imminent population decline coincident with the recent period of apparently stable coral cover. Fifty-year projections indicate the strong likelihood of extirpation of M. annularis at this particular site in St. John (in contrast to a continuation of constant low cover) and suggest that the 1988 population structure cannot be restored by recruitment. It is unlikely that the population decline will reverse until there is an amelioration of the conditions that kill individual colonies.
Historical comparisons of body size often lack pertinent details, including information on the sampling protocol and relevant ecological covariates that influence body size. Moreover, historical ...estimates of body size that rely on museum specimens may be biased towards larger size classes because of collector preferences, and thus size thresholds have been used to focus attention on maximum body size. We tested the consequences of sampling design, ecological covariates, and size thresholds on inferences of body-size change using field-contextualized historical records, rather than museum specimens. In 2014–2015, we revisited historical (1947–1963) size-frequency distributions of three gastropods (Tegula funebralis, Lottia digitalis/L. austrodigitalis, Littorina keenae) in the context of population density and tidal height. In general, gastropods declined in size. However, our inferences regarding body-size decline were tempered when the variation between sampling units was taken into consideration, resulting in greater uncertainty around the estimate of proportional change in body size. Gastropod size was correlated with population density and tidal height, and these relationships varied over time. Finally, the magnitude and direction of body-size change varied with the amount of data available for analysis, demonstrating that the use of size thresholds can lead to incomplete conclusions.
The modern biodiversity crisis reflects global extinctions and local introductions. Human activities have dramatically altered rates and scales of processes that regulate biodiversity at local scales ...1–7. Reconciling the threat of global biodiversity loss 2, 4, 6–9 with recent evidence of stability at fine spatial scales 10,11 is a major challenge and requires a nuanced approach to biodiversity change that integrates ecological understanding. With a new dataset of 471 diversity time series spanning from 1962 to 2015 from marine coastal ecosystems, we tested (1) whether biodiversity changed at local scales in recent decades, and (2) whether we can ignore ecological context (e.g., proximate human impacts, trophic level, spatial scale) and still make informative inferences regarding local change. We detected a predominant signal of increasing species richness in coastal systems since 1962 in our dataset, though net species loss was associated with localized effects of anthropogenic impacts. Our geographically extensive dataset is unlikely to be a random sample of marine coastal habitats; impacted sites (3% of our time series) were underrepresented relative to their global presence. These local-scale patterns do not contradict the prospect of accelerating global extinctions 2,4,6–9 but are consistent with local species loss in areas with direct human impacts and increases in diversity due to invasions and range expansions in lower impact areas. Attempts to detect and understand local biodiversity trends are incomplete without information on local human activities and ecological context.
•Recent temporal change in marine biodiversity was context dependent•Local net gain of species was the prevailing signal in our dataset•Biodiversity change depended on human impacts, community structure, and spatial scale•Long-term monitoring sites are unlikely to be a random sample of the global ocean
Elahi et al. use a global synthesis of marine time series to demonstrate that local biodiversity change in recent decades depended on human impacts, community structure, and spatial scale. A synthetic understanding of local biodiversity trends is incomplete without information on local ecological conditions.
The benefits of protected areas depend on compliance, and achieving protection remains a challenge in intensely used areas where conservation and socioeconomic goals are in real or apparent conflict. ...One recent innovation - satellite tracking of commercial fishing vessels - has been introduced to help with ocean protection initiatives and build trust between fishers and managers. We paired vessel traffic data before and during a temporary closure in the Adriatic Sea with data on fish nursery habitat to examine changes in fishing effort and their potential consequences. Trawlers generally complied with the closure but maintained overall effort by trawling more intensely outside of the no-trawl zone, especially near its borders and closer to shore. We detected stronger than expected fishing effort in a sub-region within the protected area, suggesting that this location should be closely monitored for compliance. Notably, fishing effort was relocated to nursery grounds for some exploited species, illustrating the importance of understanding species' life histories and habitat distribution in the design of protected areas.
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