Dataset Information

Modelling Eurasian beaver foraging habitat and dam suitability, for predicting the location and number of dams throughout catchments in Great Britain.

ABSTRACT: Eurasian beaver (Castor fiber) populations are expanding across Europe. Depending on location, beaver dams bring multiple benefits and/or require management. Using nationally available data, we developed: a Beaver Forage Index (BFI), identifying beaver foraging habitat, and a Beaver Dam Capacity (BDC) model, classifying suitability of river reaches for dam construction, to estimate location and number of dams at catchment scales. Models were executed across three catchments, in Great Britain (GB), containing beaver. An area of 6747 km² was analysed for BFI and 16,739 km of stream for BDC. Field surveys identified 258 km of channel containing beaver activity and 89 dams, providing data to test predictions. Models were evaluated using a categorical binomial Bayesian framework to calculate probability of foraging and dam construction. BFI and BDC models successfully categorised the use of reaches for foraging and damming, with higher scoring reaches being preferred. Highest scoring categories were ca. 31 and 79 times more likely to be used than the lowest for foraging and damming respectively. Zero-inflated negative binomial regression showed that modelled dam capacity was significantly related (p?=?0.01) to observed damming and was used to predict numbers of dams that may occur. Estimated densities of dams, averaged across each catchment, ranged from 0.4 to 1.6 dams/km, though local densities may be up to 30 dams/km. These models provide fundamental information describing the distribution of beaver foraging habitat, where dams may be constructed and how many may occur. This supports the development of policy and management concerning the reintroduction and recolonisation of beaver.

SUBMITTER: Graham HA

PROVIDER: S-EPMC7319418 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Modelling Eurasian beaver foraging habitat and dam suitability, for predicting the location and number of dams throughout catchments in Great Britain.

Graham Hugh A HA Puttock Alan A Macfarlane William W WW Wheaton Joseph M JM Gilbert Jordan T JT Campbell-Palmer Róisín R Elliott Mark M Gaywood Martin J MJ Anderson Karen K Brazier Richard E RE

European journal of wildlife research 20200507 3

Eurasian beaver (<i>Castor fiber</i>) populations are expanding across Europe. Depending on location, beaver dams bring multiple benefits and/or require management. Using nationally available data, we developed: a Beaver Forage Index (BFI), identifying beaver foraging habitat, and a Beaver Dam Capacity (BDC) model, classifying suitability of river reaches for dam construction, to estimate location and number of dams at catchment scales. Models were executed across three catchments, in Great Brit ...[more]

PMID: 32647501

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Project description:Beavers can profoundly alter riparian environments, most conspicuously by creating dams and wetlands. Eurasian beaver (Castor fiber) populations are increasing and it has been suggested they could play a role in the provision of multiple ecosystem services, including natural flood management. Research at different scales, in contrasting ecosystems is required to establish to what extent beavers can impact on flood regimes. Therefore, this study determines whether flow regimes and flow responses to storm events were altered following the building of beaver dams and whether a flow attenuation effect could be significantly attributed to beaver activity. Four sites were monitored where beavers have been reintroduced in England. Continuous monitoring of hydrology, before and after beaver impacts, was undertaken on streams where beavers built sequences of dams. Stream orders ranged from 2nd to 4th, in both agricultural and forest-dominated catchments. Analysis of >1000 storm events, across four sites showed an overall trend of reduced total stormflow, increased peak rainfall to peak flow lag times and reduced peak flows, all suggesting flow attenuation, following beaver impacts. Additionally, reduced high flow to low flow ratios indicated that flow regimes were overall becoming less "flashy" following beaver reintroduction. Statistical analysis, showed the effect of beaver to be statistically significant in reducing peak flows with estimated overall reductions in peak flows from -0.359 to -0.065 m3 s-1 across sites. Analysis showed spatial and temporal variability in the hydrological response to beaver between sites, depending on the level of impact and seasonality. Critically, the effect of beavers in reducing peak flows persists for the largest storms monitored, showing that even in wet conditions, beaver dams can attenuate average flood flows by up to ca. 60%. This research indicates that beavers could play a role in delivering natural flood management.

Project description:ObjectivesMiddle age has been identified as a critical time period for health later in life. Identifying factors associated with worse brain function in middle-aged adults may help identify ways to preserve brain function with aging. Our objective was to evaluate factors associated with a novel measure of brain aging in middle-aged and older adults.DesignLongitudinal cohort study.SettingBeaver Dam Offspring Study (BOSS) baseline (2005-2008), 5-year (2010-2013), and 10-year examinations (2015-2017).ParticipantsA total of 2285 adults, 22 to 84 years of age, with complete sensorineural and neurocognitive data at the 5-year examination.MeasurementsPrincipal component analysis (PCA) was performed combining 5-year sensorineural (hearing, vision, olfaction) and cognitive (Trail Making Test A and B, Digit Symbol Substitution Test, Verbal Fluency Test, Auditory Verbal Learning Test) test data. Participants with a standardized PCA score less than -1 were classified as having brain aging. Incident brain aging was defined as a PCA score less than -1 at 10 years among participants who had a PCA score of -1 or higher at 5 years. Logistic regression and Poisson models were used to estimate associations between baseline factors and prevalent or incident brain aging, respectively.ResultsOlder age, being male, current smoking, larger waist circumference, not consuming alcohol, cardiovascular disease, and interleukin-6 were associated with greater odds of prevalent brain aging, whereas more education and exercise were associated with decreased odds. In addition to age and sex, less than a college education, higher levels of soluble intercellular adhesion molecule-1, diabetes, depressive symptoms, and history of head injury were associated with an increased 5-year risk of incident brain aging.ConclusionIn the current study, vascular and inflammatory factors were associated with a new brain aging marker in middle-aged and older adults. Many of these factors are modifiable, highlighting the importance of addressing health and lifestyle factors in midlife to potentially preserve function for better brain health later in life. J Am Geriatr Soc 67:1610-1616, 2019.

Project description:ObjectiveTo describe how retinal venular diameter changes over time for an individual and to examine differences in these changes among people with different risk profiles.DesignPopulation-based cohort study.ParticipantsA total of 4600 persons aged 43 to 86 years from the Beaver Dam Eye Study (BDES) who participated in at least 1 examination and had venular diameter measured in the right eye.MethodsData from 4 examinations during a 15-year period were analyzed. Retinal venular diameter was measured from photographs at each examination by computer-assisted methods and summarized as the central retinal venular equivalent (CRVE). Associations of risk factors with concurrent CRVE measurements and changes in CRVE over time were determined using multivariate analyses.Main outcome measuresCentral retinal venular equivalent.ResultsThe CRVE tended to narrow with age. Mean CRVE was approximately 5 ?m smaller (225 vs. 230 ?m) for the average 70-year-old compared with the average 50-year-old, and was approximately 13 ?m smaller (217 vs. 230 ?m) for the average 85-year-old compared with the average 50-year-old. Male sex (beta estimate [?] = 5.24; 95% confidence interval [CI], 3.58-6.90), history of current cigarette smoking (? = 9.38; 95% CI, 8.26-10.49), and higher white blood cell (WBC) count (per 1000/?L: ? = 0.95; 95% CI, 0.74-1.16) were independently associated with larger concurrent CRVE, whereas higher mean arterial blood pressure (per 5 mmHg: ? = -0.36; 95% CI, -0.50 to -0.23) and higher serum high-density lipoprotein (HDL) cholesterol (per 10 mg/dl: ? = 0.89; 95% CI, -1.15 to -0.63) were independently associated with smaller concurrent CRVE. History of cardiovascular disease (CVD) (? = -0.16; 95% CI, -0.26 to -0.06) and presence of chronic kidney disease (CKD) (? = -0.20; 95% CI, -0.34 to -0.05) were associated with a greater decrease in CRVE over time.ConclusionsThese data show that retinal venular diameter tends to narrow with age; concurrent venular diameter is independently associated with sex, blood pressure, serum HDL cholesterol, WBC count, and history of current cigarette smoking; and change in CRVE is independently associated with a history of CVD and presence of CKD. The different independent effects of these interrelated factors on CRVE highlight the complex relationship between CRVE and systemic diseases and conditions and the difficulty in determining specific causes of change in CRVE over time.Financial disclosure(s)The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Project description:Beaver have expanded in their native habitats throughout the northern hemisphere in recent decades following reductions in trapping and reintroduction efforts. Beaver have the potential to strongly influence salmon populations in the side channels of large alluvial rivers by building dams that create pond complexes. Pond habitat may improve salmon productivity or the presence of dams may reduce productivity if dams limit habitat connectivity and inhibit fish passage. Our intent in this paper is to contrast the habitat use and production of juvenile salmon on expansive floodplains of two geomorphically similar salmon rivers: the Kol River in Kamchatka, Russia (no beavers) and the Kwethluk River in Alaska (abundant beavers), and thereby provide a case study on how beavers may influence salmonids in large floodplain rivers. We examined important rearing habitats in each floodplain, including springbrooks, beaver ponds, beaver-influenced springbrooks, and shallow shorelines of the river channel. Juvenile coho salmon dominated fish assemblages in all habitats in both rivers but other species were present. Salmon density was similar in all habitat types in the Kol, but in the Kwethluk coho and Chinook densities were 3-12× lower in mid- and late-successional beaver ponds than in springbrook and main channel habitats. In the Kol, coho condition (length: weight ratios) was similar among habitats, but Chinook condition was highest in orthofluvial springbrooks. In the Kwethluk, Chinook condition was similar among habitats, but coho condition was lowest in main channel versus other habitats (0.89 vs. 0.99-1.10). Densities of juvenile salmon were extremely low in beaver ponds located behind numerous dams in the orthofluvial zone of the Kwethluk River floodplain, whereas juvenile salmon were abundant in habitats throughout the entire floodplain in the Kol River. If beavers were not present on the Kwethluk, floodplain habitats would be fully interconnected and theoretically could produce 2× the biomass (between June-August, 1,174 vs. 667 kg) and rear 3× the number of salmon (370,000 vs. 140,000) compared to the existing condition with dams present. The highly productive Kol river produces an order of magnitude more salmon biomass and rears 40× the individuals compared to the Kwethluk. If beavers were introduced to the Kol River, we estimate that off-channel habitats would produce half as much biomass (2,705 vs. 5,404 kg) and 3× fewer individuals (1,482,346 vs. 4,856,956) owing to conversion of inter-connected, productive springbrooks into inaccessible pond complexes. We concluded that beaver dams may limit the total amount of floodplain habitat available for salmon rearing in the Kwethluk river and that the introduction of beavers to the Kol river could be detrimental to salmon populations. The introduction of beavers to other large alluvial rivers like those found in Kamchatka could have negative consequences for salmon production.

Dataset Information

Modelling Eurasian beaver foraging habitat and dam suitability, for predicting the location and number of dams throughout catchments in Great Britain.

Publications

Modelling Eurasian beaver foraging habitat and dam suitability, for predicting the location and number of dams throughout catchments in Great Britain.

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