Climatic change and wetland desiccation cause amphibian decline in Yellowstone National Park

Amphibians are a bellwether for environmental degradation, even in natural ecosystems such as Yellowstone National Park in the western United States, where species have been actively protected longer than anywhere else on Earth. We document that recent climatic warming and resultant wetland desiccation are causing severe declines in 4 once-common amphibian species native to Yellowstone. Climate monitoring over 6 decades, remote sensing, and repeated surveys of 49 ponds indicate that decreasing annual precipitation and increasing temperatures during the warmest months of the year have significantly altered the landscape and the local biological communities. Drought is now more common and more severe than at any time in the past century. Compared with 16 years ago, the number of permanently dry ponds in northern Yellowstone has increased 4-fold. Of the ponds that remain, the proportion supporting amphibians has declined significantly, as has the number of species found in each location. Our results indicate that climatic warming already has disrupted one of the best-protected ecosystems on our planet and that current assessments of species' vulnerability do not adequately consider such impacts.     

Climate change and decadal shifts in the phenology of larval fishes in the California Current ecosystem

Climate change has prompted an earlier arrival of spring in numerous ecosystems. It is uncertain whether such changes are occurring in Eastern Boundary Current Upwelling ecosystems, because these regions are subject to natural decadal climate variability, and regional climate models predict seasonal delays in upwelling. To answer this question, the phenology of 43 species of larval fishes was investigated between 1951 and 2008 off southern California. Ordination of the fish community showed earlier phenological progression in more recent years. Thirty-nine percent of seasonal peaks in larval abundance occurred earlier in the year, whereas 18% were delayed. The species whose phenology became earlier were characterized by an offshore, pelagic distribution, whereas species with delayed phenology were more likely to reside in coastal, demersal habitats. Phenological changes were more closely associated with a trend toward earlier warming of surface waters rather than decadal climate cycles, such as the Pacific Decadal Oscillation and North Pacific Gyre Oscillation. Species with long-term advances and delays in phenology reacted similarly to warming at the interannual time scale as demonstrated by responses to the El Niño Southern Oscillation. The trend toward earlier spawning was correlated with changes in sea surface temperature (SST) and mesozooplankton displacement volume, but not coastal upwelling. SST and upwelling were correlated with delays in fish phenology. For species with 20th century advances in phenology, future projections indicate that current trends will continue unabated. The fate of species with delayed phenology is less clear due to differences between Intergovernmental Panel on Climate Change models in projected upwelling trends.Phenology is the study of seasonal biological processes and how they are influenced by climate and weather. Because warmer temperatures are frequently associated with earlier phenological events, changes in phenology are common indicators of the effects of climate change on ecological communities. Meta-analyses have shown that phenological events have advanced at mean rates of 2–5 d/decade relative to a historical baseline (1–5). Among species for which phenological changes were detected, >80% of these shifts occurred in a direction consistent with climate change (1, 2, 5).Despite the inclusion of hundreds of species in meta-analyses examining climate change effects on phenology, gaps in knowledge persist because most long-term studies of phenology have monitored spring events affecting terrestrial species residing in temperate habitats in the northern hemisphere (2, 4). Marine species are particularly underrepresented in these meta-analyses (6), although see recent work by Poloczanska et al. (5). Underrepresentation of marine species is problematic not only due to their ecological importance, but also because research suggests shifts in phenology may occur more rapidly in marine environments than terrestrial ecosystems (7, 8). Compared with other marine organisms, there is a longer history of studying the phenology of teleost fishes, because the seasonal coincidence between phytoplankton blooms and fish spawning can affect recruitment to commercial fisheries (9, 10). Nevertheless, little research has investigated the impact of anthropogenic climate change on fish phenology and, with a few exceptions (11, 12), studies have been limited to a small set of commercially fished species. To address this issue, the present study investigated the influence of local and basin-scale climatic and oceanic factors on the phenology of 43 fish species whose larval abundance has been monitored off southern California since 1951.In the California Current Ecosystem (CCE), wind-driven upwelling is one of the predominant physical processes regulating the seasonal cycle of primary and secondary productivity. The seasonal onset of upwelling, referred to as the “spring transition,” is associated with the commencement of southward, alongshore winds that induce offshore Ekman transport of coastal waters (13). This process coincides with a decrease in coastal sea surface temperature (SST) by 1.5–4 °C, the development of a nearshore, southward oceanic jet, and an increase in chlorophyll a in the coastal zone (14). In the central and northern CCE (>35°N), upwelling intensifies through summer until the wind direction reverses in the fall. In the southern CCE (<35°N), upwelling is observed in all seasons, but its intensity diminishes in fall and winter (15, 16). This pattern leads to a spring maximum in chlorophyll concentration occurring between March and May in the southern CCE (17, 18). The peak in phytoplankton is followed by a summer maximum in mesozooplankton displacement volume between May and July (19). Fishes spawn in the southern CCE year round, although most species exhibit distinct seasonal patterns of larval abundance (20).There is increasing evidence that seasonal cycles of temperature, sea surface height (SSH), and chlorophyll concentration may not be stationary in the CCE (21, 22). Empirical observations and regional climate models suggest that climate change is leading to intensification of upwelling during spring and/or summer months but not other seasons (15, 23, 24). A model simulation that doubled atmospheric CO₂ indicated that upwelling off northern California is likely to increase during July–October, but decrease in April–May, resulting in a 1-mo delay in the spring transition (15). When climate feedbacks due to changes in land cover were accounted for in this model, similar results were obtained for the northern CCE, but model predictions suggested that the southern CCE would experience an increase in early-season upwelling and decreased peak and late-season upwelling (24). This change could cause an advance in the seasonal cycle of southern CCE upwelling, as well as potentially dampen its seasonal amplitude. Empirical observations of ocean temperature and the Bakun upwelling index validate these model results, indicating delays in the onset and peak of upwelling, particularly in the northern CCE (21, 25). In accordance with model predictions of earlier upwelling in the southern CCE, phytoplankton blooms were observed 1–2 mo earlier in the late 1990s in this region compared with previous years (18).In addition to anthropogenic climate change, oceanography in the CCE is affected by climate oscillations with interannual-to-decadal periods, including El Niño-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the North Pacific Gyre Oscillation (NPGO). El Niño is frequently accompanied by delays in seasonal upwelling (25), although lower frequency modes of climate variability, such as the PDO, do not have as pronounced of an effect on upwelling seasonality (19, 25). Due to delayed and reduced upwelling, El Niño is associated with later spring phytoplankton blooms in certain regions (26). Although little research has examined PDO effects on bloom timing in the CCE, this mode of climate variability influences phytoplankton phenology elsewhere in the North Pacific (27). Among zooplankton in the CCE, the 1977 change from a negative to a positive PDO coincided with a 2-mo shift toward earlier maximum displacement volume of zooplankton (19). At the next trophic level, El Niño influences the spawning phenology of northern anchovy (Engraulis mordax) (28). Also, early spawning migrations of chinook salmon (Oncorhynchus tshawytscha) are weakly correlated with warm PDO anomalies (29). The NPGO is a more recently defined climate oscillation based on the second mode of SSH variability in the Northeast Pacific (30). In the southern CCE, the NPGO is more closely correlated to variations in upwelling, salinity, nutrients, and chlorophyll than the PDO. Whether this mode of climate variability has an impact on the phenology of marine organisms is a subject yet to be investigated.The match-mismatch hypothesis provides a mechanism explaining how climate-induced changes in fish and plankton phenology could potentially alter the abundance of fish stocks (9). This hypothesis proposes that fishes spawn during peak seasonal plankton production, which increases the likelihood that their larvae will encounter sufficient prey. However, due to interannual variability in the timing of plankton production and fish spawning, these events do not always coincide. During such mismatches, first-feeding larvae may experience increased vulnerability to starvation or slower growth, which can heighten susceptibility to predation (31). Poor larval survival can result in reduced recruitment and decreased fishery landings in subsequent years. Although many other processes during the early life history of fishes influence recruitment (32), variations in plankton phenology can result in order-of-magnitude changes in the recruitment and survival of commercially important fishes (33, 34). Coastal upwelling in the CCE complicates mismatch dynamics, because upwelling simultaneously provides nutrients for planktonic production while advecting fish larvae away from coastal habitats. Due to these opposing influences on larval survival and growth, many fishes in Eastern Boundary Current Upwelling (EBCU) systems spawn at low-to-moderate rates of upwelling (9, 35).Climate change could increase phenological mismatches through two mechanisms. First, certain seasonal cues, such as day length, will not be affected by global warming, whereas other seasonal processes will exhibit differing rates of change (e.g., surface vs. bottom temperatures) (36, 37). Because predators and prey may use different environmental factors as signals to initiate seasonal behaviors, this discrepancy can lead to a higher frequency of mismatches if these indicators become decoupled (10, 36). Second, individual species inevitably have distinct climate sensitivities that result in differing rates of phenological response to climate change. These differences can lead to situations where even small changes in climate can upset seasonal, interspecific interactions (10).This study examined decadal changes in the phenology of 43 species of fish larvae off California. The objectives were to (i) determine whether phenological changes were correlated with variations in regional climate indices and the seasonality of SST, coastal upwelling, and zooplankton displacement volume; (ii) assess whether life history characteristics of fishes are linked to changes in phenology, and (iii) forecast 21st century changes in fish phenology based on predicted changes in seasonal SST and coastal upwelling.Several hypotheses can be proposed regarding how fish phenology has changed since 1951 when ichthyoplankton surveys began in the southern CCE:

• • H₀: The phenology of larval fishes will remain constant regardless of variations in seasonal oceanographic conditions.
• • H_A1: Fish larvae will uniformly occur earlier during periods with warmer temperature, reflecting earlier spawning. This change could arise due to accelerated oocyte development under warmer temperatures (38–40) or the tendency of spawning to track phytoplankton blooms, which have occurred earlier in the southern CCE in recent years (18).
• • H_A2: Spring-spawning fishes will exhibit earlier larval phenology during periods with warmer temperatures, whereas fall-spawning species will exhibit delayed phenology, reflecting a later onset of cooler, fall conditions.
• • H_A3: Delays in upwelling will lead to later spawning and occurrence of larvae.
• • H_A4: The phenology of larval fishes will display interannual-to-decadal variability synchronous with climate oscillations, such as ENSO, PDO, and/or NPGO.

To examine these hypotheses, data on the abundance of larval fishes from California Cooperative Oceanic Fisheries Investigations (CalCOFI) were used. CalCOFI has surveyed larvae between 1951 and 2008 on a monthly-to-quarterly basis (with some gaps between 1967 and 1983) (20, 41). The region most consistently surveyed by CalCOFI includes the Southern California Bight (SCB), the area offshore of the SCB, and Point Conception (Fig. S1).Open in a separate windowFig. S1.Sites where larval fish abundance was sampled. The rectangular box in the inset map shows the location of the study region relative to the West Coast of North America.Monthly abundance of 43 fish species was calculated by decadally averaging data from quarterly surveys conducted in different months in successive years. This step was undertaken to achieve the minimum of a monthly sampling resolution needed for examining phenological trends. Eight species exhibited two peaks in larval abundance each year (7, 12, 42). Because calculating CT relative to decadal means led to a small sample size for each phenophase (n = 6) and reduced statistical power, this study did not focus on species-level changes in phenology. Instead, each phenophase was treated as a replicate for examining assemblage-wide patterns. Variations in CT were treated as a proxy for spawning time, because CalCOFI mainly collects young, preflexion larvae (43, 44), and the egg stage of many species lasts 2–4 d at temperatures in the southern CCE (45). Depending on the species and temperature, flexion occurs between 3 and 25 d after hatching (45–47).

Table S1.

Ecological characteristics of larval fish species

The efficacy and applicability of a pulmonary rehabilitation programme for patients with COPD in a secondary-care community hospital

Background and objective:   Pulmonary rehabilitation is known to have beneficial effects in COPD patients. This study aimed to assess the applicability and efficacy of a pulmonary rehabilitation programme in a community hospital lacking specialist pulmonary rehabilitation services.
Methods:   This randomized, controlled, prospective study included a total of 78 patients. Questionnaires were used to collect data on sociodemographic characteristics, respiratory function tests, the Modified Medical Research Council dyspnoea scale, 6MWD, the Short Form-36 (SF-36) quality of life scale, the Hospital Anxiety and Depression Scale (HADS) and the St George's Respiratory Questionnaire (SGRQ). The experimental group underwent a pulmonary rehabilitation programme while the control group did not participate. The first, second and third month measurements for all parameters were compared between the two groups.
Results:   No significant differences in pulmonary function tests or dyspnoea scale ( P  > 0.05) were observed between the two groups. Significant differences were observed in the 6MWD measurements at the third month ( P  < 0.05), as well as in the SF-36 quality of life scale, SGRQ and HADS measurements at the second and third months ( P  < 0.01).
Conclusions:   Short-term pulmonary rehabilitation had a positive impact on exercise capacity and quality of life of patients with COPD, irrespective of FEV₁. This study demonstrated the efficacy of a pulmonary rehabilitation programme in a secondary care hospital not staffed by a specialist pulmonary rehabilitation group.     

社区医院综合干预措施对老年可能肌少症患者肌肉质量及身体功能的影响

目的 观察社区医院综合干预措施对老年可能肌少症患者肌肉质量、身体功能及生活质量的干预效果.方法 将2020年5月至7月纳入的64名老年可能肌少症患者按随机数表法随机分为2组,对照组实施并发症管理及健康教育(n=30),研究组实施包括并发症、运动、营养的综合管理(n=34).通过12周的干预,观察干预措施对2组人群小腿围...     

Temporal dynamics of soil nematode community structure under invasive <Emphasis Type="Italic">Ambrosia trifida</Emphasis> and native <Emphasis Type="Italic">Chenopodium serotinum</Emphasis>

Summary Temporal dynamics of soil nematode community structure at the depth of 0 — 30 cm was compared under invasive Ambrosia trifida and native Chenopodium serotinum in an abandoned cropland in Northeast China. The results showed the difference of nematode taxa and dominant genera under A. trifida and C. serotinum during the study period. Acrobeloides and Paratylenchus were found to be dominant genera under both A. trifida and C. serotinum. Helicotylenchus prevailed in soil with C. serotinum, while Macroposthonia was dominant in soil with A. trifida. Nematode taxa was higher under A. trifida than under C. serotinum from June to September. Except in the July, significantly higher numbers of plant-parasites were observed under A. trifida than under C. serotinum during the study period (P < 0.05). Nematode taxa, Simpson index and structure index were found to be sensitive indicators that detected nematode community structural differences under A. trifida and C. serotinum during the study period.