Decades Of Monitoring Research Articles

Flux density variability of 286 radio pulsars from a decade of monitoring

ABSTRACT The Parkes telescope has been monitoring 286 radio pulsars approximately monthly since 2007 at an observing frequency of 1.4 GHz. The wide dispersion measure (DM) range of the pulsar sample and the uniformity of the observing procedure make the data set extremely valuable for studies of flux density variability and the interstellar medium (ISM). Here, we present flux density measurements and modulation indices of these pulsars over this period. We derive the structure function from the light curves and discuss the contributions to it from measurement noise, intrinsic variability, and interstellar scintillation. Despite a large scatter, we show that the modulation index is inversely correlated with DM, and can be generally described by a power law with an index of ∼−0.7 covering DMs from ∼10 to 1000 cm−3 pc. We present refractive time-scales and/or lower limits for a group of 42 pulsars. These often have values significantly different from theoretical expectations, indicating the complex nature of the ISM along individual lines of sight. In particular, local structures and non-Kolmogorov density fluctuations are likely playing important roles in the observed flux density variation of many of these pulsars.

A 50‐year record of nitrate concentrations in the Slapton Ley Catchment, Devon, United Kingdom

AbstractSlapton Ley, a coastal lake, is the largest natural body of fresh water in south‐west England. There was concern in the 1960s that the lake was becoming increasingly eutrophic. To quantify inputs of water, sediment and nutrients into the lake, Slapton Ley Field Centre initiated a programme of weekly water quality sampling in September 1970. Of all the chemical properties which have been measured over the decades, the nitrate record has been the subject of more research than any other. The weekly monitoring has been supplemented by research projects aimed at understanding aspects of processes and patterns of nitrate delivery to the stream network. Three aspects of the nitrate record are reviewed: short‐term process dynamics; the annual cycle of influent streams and the lake itself; and long‐term trends. In the first two decades of monitoring, there was increasing concern about a trend of rising nitrate concentrations, an issue in most lowland rivers in the United Kingdom at the time. In the 1990s, nitrate concentrations levelled off and then have fallen steadily in recent years. In relation to eutrophication, there are clear signs of improvement in the influent streams, but concerns remain about water quality in the lake itself.

The chemical composition of the accretion disc and donor star in ultra-compact X-ray binaries: A comprehensive X-ray analysis

ABSTRACT We have analysed the X-ray spectra of all known Ultra-Compact X-ray Binaries (UCXBs), with the purpose of constraining the chemical composition of their accretion disc and donor star. Our investigation was focused on the presence (or absence) of the Fe Kα emission line, which was used as the probe of chemical composition of the disc, based on previously established theoretical predictions for the reflection of X-ray radiation off the surface of C/O-rich or He-rich accretion discs in UCXBs. We have contrasted the results of our spectral analysis to the history of type I X-ray bursts from these systems, which can also indicate donor star composition. We found that UCXBs with prominent and persistent iron Kα emission also featured repeat bursting activity. On the other hand, the UCXBs for which no iron line was detected, appear to have few or no type I X-ray bursts detected over more than a decade of monitoring. Based on Monte Carlo simulations, demonstrating a strong correlation between the Fe Kα line strength and the abundance of C and O in the accretion disc material and given the expected correlation between the H/He abundance and the recurrence rate of type I X-ray bursts, we propose that there is a considerable likelihood that UCXBs with persistent iron emission have He-rich donors, while those that do not, likely have C/O or O/Ne/Mg-rich donors. Our result strongly advocate for the development of more sophisticated simulations of X-ray reflection from hydrogen-poor accretion discs.

Apparent breeding success drives long‐term population dynamics of a migratory swan

The ability of a species to adapt to environmental change is ultimately reflected in its vital rates – i.e. survival and reproductive success of individuals. Together, vital rates determine trends in numbers, commonly monitored using counts of species abundance. Rapid changes in abundance can give rise to concern, leading to calls for research into the biological mechanisms underlying variations in demography. For the northwest European population of Bewick's swanCygnus columbianus bewickii, there have been major changes in the population trends recorded during nearly five decades of monitoring (1970–2016). The total number of birds increased to a maximum of ca 30 000 in 1995 and subsequently decreased to about 18 000 individuals in 2010. Such large fluctuation in population numbers is rare in long‐lived species and understanding the drivers of this population change is crucial for species management and conservation. Using the integrated population model (IPM) framework, we analysed three demographic datasets in combination: population counts, capture–mark–resightings (CMR) and the proportion of juveniles in winter over a period of ~50 years. We found higher apparent breeding success in the years when the population had a positive growth rate compared to years with a negative growth rate. Moreover, no consistent trend in adult and yearling survival, and an increasing trend in juvenile survival was found. A transient life‐table response experiment showed that apparent breeding success and adult survival contributed most to the variation in population trend. We explored possible explanatory variables for the different demographic rates and found a significant association between juvenile survival both with the water level in lakes during autumn migration, which affects food accessibility for the swans, and with summer temperatures. Such associations are important for understanding the dynamics of species with fluctuating population sizes, and thus for informing management and conservation decisions.

Die–offs, reproductive failure, and changing at–sea abundance of murres in the Bering and Chukchi Seas in 2018

Common and thick–billed murres are among the most numerous and widespread seabirds in the northern hemisphere though they appear to be especially susceptible to mass die–off events. During the spring and summer of 2018, the Bering Sea experienced warmer than average sea temperatures following a winter of unprecedented, near complete lack of sea ice. To determine if breeding murres were negatively affected by these warm sea temperatures, surveys at most of the major murre breeding colonies in the eastern Bering and eastern Chukchi seas were conducted during the 2018 breeding season. Nearly all colonies surveyed experienced near-complete reproductive failure. Concurrently, above average levels of murre mortality were observed, primarily at St. Lawrence Island and in the Bering Strait region. The timing of this mortality is somewhat unusual and concerning as it occurred during the breeding season. Based on surveys at sea, overall murre abundance offshore was generally lower in 2018 compared to recent years (2012–2017), particularly in the northern Bering Sea, yet mean density for thick–billed murres increased in the Chukchi Sea. Reproductive failure is rare at monitored murre colonies within the study area and the widespread reproductive failures observed in 2018 were unprecedented over four decades of monitoring, but consistent with the reproductive failure of murres documented in the Gulf of Alaska and southeastern Bering Sea following a large murre die–off in 2015–2016. The combination of large–scale reproductive failure, evidence of elevated levels of mortality, and low abundance of birds offshore suggest that murres experienced severe distress in the Bering and Chukchi sea region during the summer of 2018.

Outsized nutrient contributions from small tributaries to a Great Lake

Excessive nitrogen (N) and phosphorus (P) loading is one of the greatest threats to aquatic ecosystems in the Anthropocene, causing eutrophication of rivers, lakes, and marine coastlines worldwide. For lakes across the United States, eutrophication is driven largely by nonpoint nutrient sources from tributaries that drain surrounding watersheds. Decades of monitoring and regulatory efforts have paid little attention to small tributaries of large water bodies, despite their ubiquity and potential local importance. We used a snapshot of nutrient inputs from nearly all tributaries of Lake Michigan-the world's fifth largest freshwater lake by volume-to determine how land cover and dams alter nutrient inputs across watershed sizes. Loads, concentrations, stoichiometry (N:P), and bioavailability (percentage dissolved inorganic nutrients) varied by orders of magnitude among tributaries, creating a mosaic of coastal nutrient inputs. The 6 largest of 235 tributaries accounted for ∼70% of the daily N and P delivered to Lake Michigan. However, small tributaries exhibited nutrient loads that were high for their size and biased toward dissolved inorganic forms. Higher bioavailability of nutrients from small watersheds suggests greater potential to fuel algal blooms in coastal areas, especially given the likelihood that their plumes become trapped and then overlap in the nearshore zone. Our findings reveal an underappreciated role that small streams may play in driving coastal eutrophication in large water bodies. Although they represent only a modest proportion of lake-wide loads, expanding nutrient management efforts to address smaller watersheds could reduce the ecological impacts of nutrient loading on valuable nearshore ecosystems.

Effects of Post-Fire Vegetation Recovery on Soil Erosion in Vulnerable Montane Regions in a Monsoon Climate: A Decade of Monitoring

In areas with frequent fires and erosive soils under monsoon climate, we aimed to determine the long-term dynamics of soil loss during vegetation recovery and to examine elapsed time for soil stabilization. Runoff plots were installed in Pinus densiflora forests affected by stand-replacing fires on the East Coast of South Korea, which occurred in spring 2000. Runoff plots measured runoff and sediment yields for 11 years (2003–2013) during which time, vegetation cover of low-, intermediate-, and high-vegetation cover plots increased from 21 to 44%, 49% to 69%, and 87% to 95%, respectively. Vegetation was effective in preventing runoff and sediment yield. Nevertheless, to stabilize to below baseline load, it took 7 years at low and intermediate cover plots and only 3 years at high cover plots. For 7 years, 7.06 (5.2-fold) and 4.29 (3.1-fold) kg m−2 of soil were lost at the low and intermediate cover plots, respectively, compared to the high cover plots (1.37 kg m−2). Sediment loss fluctuated more than runoff following extreme rainfall events. We suggest that for the slow recovery area ( 70% cover).

Monte Carlo estimation of the probability of causal contacts between communicating civilizations

AbstractIn this work we address the problem of estimating the probabilities of causal contacts between civilizations in the Galaxy. We make no assumptions regarding the origin and evolution of intelligent life. We simply assume a network of causally connected nodes. These nodes refer somehow to intelligent agents with the capacity of receiving and emitting electromagnetic signals. Here we present a three-parametric statistical Monte Carlo model of the network in a simplified sketch of the Galaxy. Our goal, using Monte Carlo simulations, is to explore the parameter space and analyse the probabilities of causal contacts. We find that the odds to make a contact over decades of monitoring are low for most models, except for those of a galaxy densely populated with long-standing civilizations. We also find that the probability of causal contacts increases with the lifetime of civilizations more significantly than with the number of active civilizations. We show that the maximum probability of making a contact occurs when a civilization discovers the required communication technology.

An ecosystem-wide reproductive failure with more snow in the Arctic.

2018: Arctic researchers have just witnessed another extreme summer—but in a new sense of the word. Although public interest has long been focused on general warming trends and trends towards a lower sea ice cover in the Arctic Ocean, this summer saw the realization of another predicted trend: that of increasing precipitation during the winter months and of increased year-to-year variability. In a well-studied ecosystem in Northeast Greenland, this resulted in the most complete reproductive failure encountered in the terrestrial ecosystem during more than two decades of monitoring: only a few animals and plants were able to reproduce because of abundant and late melting snow. These observations, we suggest, should open our eyes to potentially drastic consequences of predicted changes in both the mean and the variability of arctic climate.

Temporal changes in fish diversity in lotic and lentic environments along a reservoir cascade

Abstract Long‐term modifications in hydrological conditions due to river damming result in varied effects on fish diversity, which can be stronger in a reservoir cascade. Therefore, we assessed changes in fish diversity over a 28‐year period, in a series of reservoirs along the Araguari River Basin, a Neotropical drainage in Brazil, in both lentic environments (reservoirs) and the lotic stretches between them. We used linear mixed models to assess long‐term changes in fish diversity. Diversity was measured as α diversity (fish species richness) and β diversity (Jaccard's and Raup–Crick's dissimilarity index). Beta diversity was then partitioned into turnover (species replacement) and nestedness (species loss). To understand fish species replacement along the cascade, we modelled turnover with four covariates: age, richness of native and non‐native fish species, and longitudinal position of sampling site along the cascade. The reduction of total richness and the increase in non‐native richness were related to reservoir age. These effects were similar in both lotic and lentic environments, with no significant difference between them. We also observed a decrease in native fish richness over time, with a slight tendency for lentic environments to lose more species than lotic environments. Dissimilarity in fish assemblage increased over time and β Raup–Crick results corroborated those derived from β Jaccard, yielding similar significant temporal trends. Changes in fish species composition occurred predominantly due to turnover, compared to nestedness. We observed a greater species loss in reservoirs, suggesting that the transformation from a lotic environment into a lentic had greater impact on fish assemblages than the flow regulation of the lotic stretches downstream of the dams. Our results suggest that species replacement can be explained mainly by the increase of non‐native fish richness, followed by the longitudinal position along the cascade in an upstream–downstream direction, and reservoir age. This study reveals that, even after 2 decades of monitoring, we still observe important changes in fish assemblages, demonstrating the importance of long‐term monitoring to assess biodiversity. Our findings reinforce the importance of long‐term fish monitoring schemes for the investigation of the effects of non‐native fish species on native fish assemblages.

Nitrate on a Slow Decline: Watershed Water Quality Response during Two Decades of Tallgrass Prairie Ecosystem Reconstruction in Iowa

The Neal Smith National Wildlife Refuge was established as a tallgrass prairie ecosystem reconstruction in the Walnut Creek watershed (5238 ha), Jasper County, Iowa, with >1200 ha of prairie plantings initiated between 1993 and 2006. This study updates the documented decreases in watershed NO-N losses that accompanied this change in land cover to a 20-yr record. Annual flow-weighted NO-N concentrations declined by 0.15 mg NO-N L yr, which was not significantly different from the rate of 0.07 mg NO-N L yr reported after the first decade of monitoring. There was also evidence ( < 0.1) that prairie reconstruction led to a declining trend in annual watershed water yield, which would have contributed to the trend of decreasing NO-N loads. However, variability in climate, including 2 yr with significant flooding events followed by a major drought during the second decade of monitoring, challenged any notion that a watershed water quality record will stabilize even >10 yr after a substantial change in land cover, in this naturally drained watershed underlain by fine grained glacial deposits that exhibit multidecadal groundwater transport times. Efforts to document progress toward water quality goals will need to consider dominant flow paths and associated travel times, uncertainty in the effectiveness of management changes, and a changeable climate.

Eruptions in sync: Improved constraints on Kīlauea Volcano's hydraulic connection

Kīlauea Volcano is an archetype for the complex interactions that can occur between a volcano's summit and flanks. Decades of monitoring at Kīlauea have demonstrated that magma rises beneath the summit and flows laterally at shallow depths to erupt along the rift zones. Kīlauea's recent eruptions at Halema‘uma‘u and Pu‘u ‘Ō‘ō mark the first time in the historic record that long-term (>1 year) eruptions have been concurrent at the summit and a rift zone, offering a new opportunity to improve our understanding of the relationship between these two segments of the magmatic system. While magma supply rate beneath the summit has been shown in previous studies to be a primary control on magmatic system pressure and eruptive activity, the role of the eruptive vent has been less clear. Our study shows that a dynamic equilibrium is maintained between Kīlauea's summit and East Rift Zone (ERZ) eruptive vent—and lava lake level fluctuations are closely coupled at the two eruption sites—providing new constraints on the hydraulic connection and ERZ conduit. We show that localized changes at the ERZ eruption site during 2010–2011 regulated summit behavior in an uprift direction over distances of ∼20 km. Changes in the elevation and efficiency of the ERZ vent affect pressure in Kīlauea's magmatic system and impact summit behavior. Thus, the hydraulic connection between the summit and rift zone is a “two-way street” that transmits both downrift- and uprift-directed changes. Our results support recent work at other volcanoes that shows a complex interplay between a volcano's summit reservoir and flank conduit during flank eruptions, and suggest that explosive summit activity may in some cases be triggered by changes far away on a volcano's rift. These concepts were reinforced by the historic eruptive activity on Kīlauea that occurred during May–August 2018, when the manuscript was being revised.

Two decades of monitoring in marine debris ingestion in loggerhead sea turtle, Caretta caretta, from the western Mediterranean

Anthropogenic marine debris is one of the major worldwide threats to marine ecosystems. The EU Marine Strategy Framework Directive (MSFD) has established a protocol for data collection on marine debris from the gut contents of the loggerhead sea turtle (Caretta caretta), and for determining assessment values of plastics for Good Environmental Status (GES). GES values are calculated as percent turtles having more than average plastic weight per turtle. In the present study, we quantify marine debris ingestion in 155 loggerhead sea turtles collected in the period 1995–2016 in waters of western Mediterranean (North-east Spain). The study aims (1) to update and standardize debris ingestion data available from this area, (2) to analyse this issue over two decades using Zero-altered (hurdle) models and (3) to provide new data to compare the only GES value available (off Italian waters). The composition of marine debris (occurrence and amounts of different categories) was similar to that found in other studies for the western Mediterranean and their amounts seem not to be an important threat to turtle survival in the region. Model results suggest that, in the study area, (a) period of stranding or capture, (b) turtle size and (c) latitude are significant predictors of anthropogenic debris ingestion (occurrence and amount) in turtles. The GES value for late juvenile turtles (CCL>40 cm) has decreased in the last ten years in the study area, and this is very similar to that obtained in Italian waters. We also provide a GES value for early juvenile turtles (CCL≤40 cm) for the first time. Recommendations arising from this study include ensuring use of (1) the standardized protocol proposed by the MSFD for assessing marine debris ingestion by loggerhead sea turtles and (2) the ecology of the turtles (neritic vs oceanic), rather than their size, to obtain GES values.

Air monitoring of new and legacy POPs in the Group of Latin America and Caribbean (GRULAC) region

A special initiative in the Global Atmospheric Passive Sampling (GAPS) Network was implemented to provide information on new and emerging persistent organic pollutants (POPs) in the Group of Latin America and Caribbean (GRULAC) region. Regional-scale atmospheric concentrations of the new and emerging POPs hexachlorobutadiene (HCBD), pentachloroanisole (PCA) and dicofol indicators (breakdown products) are reported for the first time. HCBD was detected in similar concentrations at all location types (<20–120 pg/m3). PCA had elevated concentrations at the urban site Concepción (Chile) of 49–222 pg/m3, with concentrations ranging <1–8.5 pg/m3 at the other sites in this study. Dicofol indicators were detected at the agricultural site of Sonora (Mexico) at concentrations ranging 30–117 pg/m3. Legacy POPs, including a range of organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs), were also monitored to compare regional atmospheric concentrations over a decade of monitoring under the GAPS Network. γ-hexachlorocyclohexane (HCH) and the endosulfans significantly decreased (p < 0.05) from 2005 to 2015, suggesting regional levels are decreasing. However, there were no significant changes for the other legacy POPs monitored, likely a reflection of the persistency and slow decline of environmental levels of these POPs. For the more volatile OCs, atmospheric concentrations derived from polyurethane foam (PUF) (acting as an equilibrium sampler) and sorbent impregnated PUF (SIP) (acting as a linear phase sampler), were compared. The complimentary methods show a good agreement of within a factor of 2–3, and areas for future studies to improve this agreement are further discussed.

Survival and growth of tuataraSphenodon punctatusfollowing translocation from the Cook Strait to warmer locations in their historic range

AbstractPost-translocation monitoring is fundamental for assessing translocation success and identifying potential threats. We measured outcomes for four cohorts of tuataraSphenodon punctatustranslocated to warmer climates outside of their ecological region, to understand effects of climate warming. Translocation sites were on average 2–4 °C warmer than the source site. We used three short-term measures of success: survival, growth and reproduction. Data on recaptures, morphometric measurements, and reproduction were gathered over 2.5 years following release. Although decades of monitoring will be required to determine long-term translocation success in this species, we provide an interim measure of population progress and translocation site suitability. We found favourable recapture numbers, growth of founders and evidence of reproduction at most sites, with greater increases in body mass observed at warmer, less densely populated sites. Variable growth in the adult population at one translocation site suggested that higher population density, intraspecific competition, and lower water availability could be responsible for substantial weight loss in multiple individuals, and we make management recommendations to reduce population density. Overall, we found that sites with warmer climates and lower population densities were potentially beneficial to translocated tuatara, probably because of enhanced temperature-dependent and density-dependent growth rates. We conclude that tuatara could benefit from translocations to warmer sites in the short term, but further monitoring of this long-lived species is required to determine longer-term population viability following translocation. Future vulnerability to rising air temperatures, associated water availability, and community and ecosystem changes beyond the scope of this study must be considered.

Managing forest habitat for conservation-reliant species in a changing climate: The case of the endangered Kirtland’s Warbler

Conservation and recovery of species of concern necessitates evaluating forest habitat conditions under changing climate conditions, especially in the early stages of the delisting process. Managers must weigh implications of near-term habitat management activities within the context of changing environmental conditions and a species’ biological traits that may influence their vulnerability to changing conditions. Here we applied established population-habitat relationships based on decades of monitoring and research-management collaborations for the Kirtland’s Warbler (Setophaga kirtlandii) to project potential impacts of changing environmental conditions to breeding habitat distribution, quantity, and quality in the near future. Kirtland’s warblers are habitat-specialists that nest exclusively within dense jack pine (Pinus banksiana) forests between ca. 5–20 years of age. Using Random Forests to predict changes in distribution and growth rate of jack pine under future scenarios, results indicate the projected distribution of jack pine will contract considerably (ca. 75%) throughout the Lake States region, U.S.A. in response to projected environmental conditions in 2099 under RCP 4.5 and 8.5 climate scenarios regardless of climate model. Reduced suitability for jack pine regeneration across the Lake States may constrain management options, especially for creating high stem-density plantations nesting habitat. However, conditions remain suitable for jack pine regeneration within their historical and current core breeding range in northern Lower Michigan and several satellite breeding areas. Projected changes in jack pine growth rates varied within the core breeding area, but altered growth rates did not greatly alter the duration that habitat remained suitable for nesting by the Kirtland’s Warblers. These findings contribute to Kirtland’s Warbler conservation by informing habitat spatial planning of plantation management to provide a constant supply of nesting habitat based on the spatial variability of potential loss or gain of lands environmentally suitable for regenerating jack pine in the long-term.

Organochlorine contaminants in the Vistula Lagoon sedimentation zone as possible source of lagoon recontamination.

The presented results include decade of monitoring of the Vistula Lagoon waters and have been supplemented by the determination of chlorinated compounds, as well as on concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the sedimentation zone. Monitoring of river waters entering the Polish part of the lagoon and the lagoon waters confirmed the presence of plant protection chemical; the largest contributors has lindane (34%) and DDTtotal (21%); the same as for sediments were dominate lindane (19%) and DDTtotal (14%) within pp-DDT isomer dominate (13%). In the lagoon water, PCDD/Fs were determined within a range of 1.5-5.6ngdm-3, leading to average toxicity of 0.18 ± 0.13ng TEQ·dm-3. In sediments, their concentrations fell within a range of 22.7-405.7ngkg-1 dw and the average toxicity of the lagoon sediments was set at 5.00 ± 1.98ng TEQ·kg-1 dw. Both in water and sediments, the greatest share among PCDD/Fs has octa-chlorodibenzodioxin. Due to the hydromorphological conditions of the lagoon, the waters are mixed to the bottom causing the surface layer of sediment to become remobilized-this is suggested as the key factor when it comes to water recontamination and increased access of POPs to marine organisms.

Efficacy of an established marine protected area at sustaining a queen conch Lobatus gigas population during three decades of monitoring

Efficacy of an established marine protected area at sustaining a queen conch Lobatus gigas population during three decades of monitoring

Prevalence and levels of deoxynivalenol and zearalenone in commercial barley and wheat grain produced in Southern Brazil: an eight-year (2008 to 2015) summary

Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is one of the most important diseases of barley and wheat in Brazil. The disease causes yield losses and contaminates grain with mycotoxins produced by the fungus, mainly deoxynivalenol (DON) and zearalenone (ZEA). The objective of this study was to summarize the results of 16,487 analyses of DON and ZEA in barley and wheat commercial grain produced in Brazil from 2008 to 2015 using liquid chromatography tandem-mass spectrometry. For barley, DON and ZEA were detected in 67% and 41% of the samples, respectively, but 19% and 18% were above the maximum tolerated limits (MTL = 1250 μg/kg for DON and 100 μg/kg for ZEA). For wheat, DON and ZEA were detected in 73 and 38% with 30% and 9% of the samples above the MTL (1250 μg/kg for DON and 200 μg/kg for ZEA). The overall mean concentration of DON was 737 μg/kg in barley and 660 μg/kg in wheat. The mean yearly DON levels varied less in barley (446 μg/kg to 1114 μg/kg) compared to wheat (346 μg/kg to 1274 μg/kg). For the latter, a high peak of DON was found in 2014 when 58% of the samples were above the MTL and the toxin levels averaged 1274 μg/kg across all samples. The mean yearly concentration of ZEA was 138 and 111 μg/kg for barley and wheat, respectively, with the highest prevalence and concentration reported in 2008 and 2009, for both crops. To our knowledge, this is the most comprehensive summary of DON and ZEA contamination in barley and wheat in Brazil for almost a decade of monitoring. Continuous assessment and close inspection of highly contaminated batches are essential to ensure food safety and mitigate the risk that these mycotoxins can cause to human and animal health.

Twenty-six Years After the Exxon Valdez Oil Spill: Volunteers Continue Monitor Long-term Variability of Intertidal Biology in Western Prince William Sound

Marine populations - including fisheries, plankton, seabirds, kelp beds and biota of exposed rocky shorelines - undergo dramatic long term and inter-annual variability due in part to climate variability. Less is known about long-term variability of inter-tidal marine populations on protected rocky shorelines impacted by oil spills. Following over a decade (1989 to 2000) of detailed monitoring of rocky intertidal marine life at previously oiled and unoiled sites in Prince William Sound, the senior author continued photo-monitoring at up to nine sites, with substantial and grateful assistance of other scientists and local citizens. These observations, between 2001 and 2016, added 15 years to the previous 11 years of detailed intertidal monitoring conducted by NOAA HazMat. Further, a landslide in 2000 produced a 300 m long bare rock intertidal surface, not unlike oiled rocky sites areas that were subjected to high-pressure hot-water washing in 1989. This provided an additional unique opportunity to document colonization of fresh substrate on a bare-rock shoreline for more than 12 years. Recovery of conspicuous rocky inter-tidal biota on nearly barren surfaces occurred rapidly and returned to within the range of natural variability in 3 to 4 years. The additional decades of monitoring helped confirm the nature of natural variability and further that there have been 4 - o 10-year fluctuations in the abundance (percent cover) of dominant seaweeds and mussels in Western Prince William Sound. Four periods of heavy rockweed cover were separated by many years of little or no cover both at previously-oiled and unoiled sites indicating this variability had little to do with the spill and subsequent clean up. This variability challenged a common definition of recovery (return to conditions prior to the spill), and added further support to the results of our first decade of detailed monitoring that recovery may be defined as “a return to within the natural range of variability”. This poster acknowledges the assistance of volunteers who went out of their way to visit and photograph the sites, describes the approach and methods used during the most recent 15 years provides graphics highlighting the long-term and inter-annual variability and, hopefully, stimulates others to use annual photography to document and visualize linter-annual biological variability and long-term changes in shoreline biology.