Biodiversity Research Institute

Population declines of migratory songbird species throughout their range are well documented and have been associated with a complex variety of stressors, including, but not limited to: environmental pollution; habitat loss, conversion, and fragmentation; energy development and generation; and climate change. To better understand these and other potential impacts on songbird populations, biologists from Biodiversity Research Institute (BRI) collect scientific data to address these stressors through studies that target mercury exposure and effects assessments, determine movement and distribution patterns, and integrate findings with conservation and management strategies. Through an emphasis on neotropical migrant species, BRI has conducted research at various locations within the United States, particularly the northeastern U.S., as well as study sites in Central and South America, the Caribbean Islands, and China. With an overarching approach centered on the assessment of environmental stressors on wildlife health, BRI songbird studies are designed to advance scientific knowledge and to contribute valuable data to inform policy, assist in management decisions, and establish conservation initiatives for local, regional, and global songbird populations

Bioaccumulation and Biomagnification of Mercury and Methylmercury in Four Sympatric Coastal Sharks in a Protected Subtropical Lagoon

Mercury bioaccumulation is frequently observed in marine ecosystems, often with stronger effects at higher trophic levels. We compared total mercury (THg) and methylmercury (MeHg) from muscle with length, comparative isotopic niche, and diet (via δ13C and δ15N) among four sympatric coastal sharks in Florida Bay (USA): blacknose, blacktip, bull, and lemon. Mercury in blacknose and blacktip sharks increased significantly with size, whereas bull and lemon sharks had a high variance in mercury relative to size. Both δ13C and δ15N were consistent with general resource use and trophic position relationships across all species. A significant relationship was observed between δ13C and mercury in blacktip sharks, suggesting an ontogenetic shift isotopic niche, possibly a dietary change. Multiple regression showed that δ13C and δ15N were the strongest factors regarding mercury bioaccumulation in individuals across all species. Additional research is recommended to resolve the mechanisms that determine mercury biomagnification in individual shark species

Derivation of screening benchmarks for dietary methylmercury exposure for the common loon ( Gavia immer ): Rationale for use in ecological risk assessment

The current understanding of methylmercury (MeHg) toxicity to avian species has improved considerably in recent years and indicates that exposure to environmentally relevant concentrations of MeHg through the diet can adversely affect various aspects of avian health, reproduction, and survival. Because fish‐eating birds are at particular risk for elevated MeHg exposure, the authors surveyed the available primary and secondary literature to summarize the effects of dietary MeHg on the common loon ( Gavia immer ) and to derive ecologically relevant toxic thresholds for dietary exposure to MeHg in fish prey. After considering the available data, the authors propose three screening benchmarks of 0.1, 0.18, and 0.4 µg g −1 wet weight MeHg in prey fish. The lowest benchmark (0.1 µg g −1 wet wt) is the threshold for adverse behavioral impacts in adult loons and is close to the empirically determined no observed adverse effects level for subclinical effects observed in captive loon chicks. The remaining benchmarks (0.18 and 0.4 µg g −1 wet wt) correspond to MeHg levels in prey fish associated with significant reproductive impairment and reproductive failure in wild adult loons. Overall, these benchmarks incorporate recent findings and reviews of MeHg toxicity in aquatic fish‐eating birds and provide the basis for a national ecological risk assessment for Hg and loons in Canada. Environ. Toxicol. Chem. 2012; 31: 2399–2407. © 2012 SETACPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/93756/1/1971_ftp.pd

Mercury Contamination in Forest and Freshwater Ecosystems in the Northeastern United States

Eastern North America receives elevated atmospheric mercury deposition from a combination of local, regional, and global sources. Anthropogenic emissions originate largely from electric utilities, incinerators, and industrial processes. The mercury species in these emissions have variable atmospheric residence times, which influence their atmospheric transport and deposition patterns. Forested regions with a prevalence of wetlands and of unproductive surface waters promote high concentrations of mercury in freshwater biota and thus are particularly sensitive to mercury deposition. Through fish consumption, humans and wildlife are exposed to methylmercury, which markedly bioaccumulates up the freshwater food chain. Average mercury concentrations in yellow perch fillets exceed the Environmental Protection Agency’s human health criterion across the region, and mercury concentrations are high enough in piscivorous wildlife to cause adverse behavioral, physiological, and reproductive effects. Initiatives are under way to decrease mercury emissions from electric utilities in the United States by roughly 70%

Selection of human-influenced and natural wetlands by Great Egrets at multiple scales in the southeastern USA

ABSTRACT Wetlands constructed or modified by humans (human-influenced wetlands [HIW]) constitute an increasing proportion of wetland habitat in the USA. It is unclear to what extent HIW (e.g., ponds, reservoirs, impoundments, aquaculture sites, and flooded agricultural fields) provide equivalent habitat for wading birds compared with the natural wetlands they are replacing or augmenting. We compared selection of HIW with natural wetlands by Great Egrets (Ardea alba) in 2 regions containing high proportions of wetlands (73% Louisiana [LA], 39% South Carolina [SC]) and similar proportions of HIW (4.3% LA, 4.5% SC). Great Egrets in LA (n ¼ 11) and SC (n ¼ 19) were tracked using satellite transmitters for up to 1 year to assess selection of home ranges and foraging sites. We also compared selection of flooded agricultural fields vs. natural wetlands as foraging sites from aerial surveys of untagged egrets in LA. In SC, tagged birds showed stronger selection for HIW than natural wetlands as foraging sites, driven by use of small manmade ponds (39.9% of foraging observations), but home ranges did not contain a disproportionate area of ponds. In LA, tagged birds showed no overall selection of HIW at either scale, but unmarked egrets showed strong selection for crayfish aquaculture ponds, especially during drawdown. Rice fields provided only a short window of opportunity for foraging Great Egrets and were not selected over nearby natural sites. Despite widespread availability of HIW in the southeastern USA, our results show that natural wetlands continue to provide the majority of foraging habitat for Great Egrets; however, some HIW types (aquaculture and small ponds) may be strongly selected. Keywords: artificial wetland, agricultural wetland, habitat selection, rice, crayfish, ponds, Great Egret, Ardea alba Selección por parte de Ardea alba de humedales con influencia humana y naturales a múltiples escalas en el sudeste de EEUU RESUMEN Los humedales construidos o modificados por los humanos (Humedales con Influencia Humana, HIH) constituyen una proporción creciente del hábitat de humedal en los EEUU. No está claro en qué medida los HIH (e.g., estanques, diques, embalses, sitios de acuicultura y campos de cultivo inundados) brindan un hábitat equivalente para las aves zancudas comparados con los humedales naturales que están reemplazando o aumentando. Comparamos la selección de HIH con humedales naturales por parte de Ardea alba en dos regiones con una alta proporción de humedales (73% Luisiana [LA], 39% Carolina del Sur [CS]) y con una proporción similar de HIH (4.3% LA, 4.5% CS). Seguimos individuos de A. alba en LA (n ¼ 11) y CS (n ¼ 19) mediante el uso de transmisores satelitales hasta por un año para evaluar la selección de los ámbitos de hogar y de los sitios de forrajeo. También comparamos la selección de los campos de cultivo inundados versus los humedales naturales como sitios de forrajeo a partir de muestreos aéreos de individuos no marcados en LA. En CS, las aves marcadas mostraron una selección más fuerte de HIH que de humedales naturales como sitios de forrajeo, impulsada por el uso de pequeños estanques antrópicos (39.9% de las observaciones de forrajeo), pero los ámbitos de hogar no presentaron una superficie desproporcionada de estanques. En LA, las aves marcadas no mostraron una selección global de HIH a cualquier escala, pero los individuos no marcados mostraron una fuerte selección de estanques de acuicultura de cangrejos de río, especialmente durante el descenso en el nivel de agua. Los campos de arroz brindaron solo una corta ventana de oportunidad para los individuos que forrajeaban y no fueron seleccionados por sobre sitios naturales cercanos. A pesar de la amplia disponibilidad de HIH en el sudeste de EEUU, nuestros resultados muestran que los humedales naturales continúan brindando la mayoría de los hábitats de forrajeo para A. alba. Sin embargo, algunos tipos de HIH (acuicultura y pequeños estanques) pueden ser fuertemente seleccionados. Palabras clave: Ardea alba, arroz, cangrejo de río, estanques, humedal agrícola, humedal artificial, selección de hábitat Q 2016 Cooper Ornithological Society

Understanding sources of methylmercury in songbirds with stable mercury isotopes: Challenges and future directions

Mercury (Hg) stable isotope analysis is an emerging technique that has contributed to a better understanding of many aspects of the biogeochemical cycling of Hg in the environment. However, no study has yet evaluated its usefulness in elucidating the sources of methylmercury (MeHg) in songbird species, a common organism for biomonitoring of Hg in forested ecosystems. In the present pilot study, we examined stable mercury isotope ratios in blood of 4 species of songbirds and the invertebrates they are likely foraging on in multiple habitats in a small watershed of mixed forest and wetlands in Acadia National Park in Maine (USA). We found distinct isotopic signatures of MeHg in invertebrates (both massâ dependent fractionation [as δ202Hg] and massâ independent fractionation [as Î 199Hg]) among 3 interconnected aquatic habitats. It appears that the Hg isotopic compositions in bird blood cannot be fully accounted for by the isotopic compositions of MeHg in lower trophic levels in each of the habitats examined. Furthermore, the bird blood isotope results cannot be simply explained by an isotopic offset as a result of metabolic fractionation of δ202Hg (e.g., internal demethylation). Our results suggest that many of the birds sampled obtain MeHg from sources outside the habitat they were captured in. Our findings also indicate that massâ independent fractionation is a more reliable and conservative tracer than massâ dependent fractionation for identifying sources of MeHg in bird blood. The results demonstrate the feasibility of Hg isotope studies of songbirds but suggest that larger numbers of samples and an expanded geographic area of study may be required for conclusive interpretation. Environ Toxicol Chem 2018;37:166â 174. © 2017 SETACPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141144/1/etc3941.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141144/2/etc3941_am.pd

Addressing chemical pollution in biodiversity research

Climate change, biodiversity loss, and chemical pollution are planetary-scale emergencies requiring urgent mitigation actions. As these “triple crises” are deeply interlinked, they need to be tackled in an integrative manner. However, while climate change and biodiversity are often studied together, chemical pollution as a global change factor contributing to worldwide biodiversity loss has received much less attention in biodiversity research so far. Here, we review evidence showing that the multifaceted effects of anthropogenic chemicals in the environment are posing a growing threat to biodiversity and ecosystems. Therefore, failure to account for pollution effects may significantly undermine the success of biodiversity protection efforts. We argue that progress in understanding and counteracting the negative impact of chemical pollution on biodiversity requires collective efforts of scientists from different disciplines, including but not limited to ecology, ecotoxicology, and environmental chemistry. Importantly, recent developments in these fields have now enabled comprehensive studies that could efficiently address the manifold interactions between chemicals and ecosystems. Based on their experience with intricate studies of biodiversity, ecologists are well equipped to embrace the additional challenge of chemical complexity through interdisciplinary collaborations. This offers a unique opportunity to jointly advance a seminal frontier in pollution ecology and facilitate the development of innovative solutions for environmental protection

Effects of Water-Level Management on Nesting Success of Common Loons

Water-level management is widespread and illustrates how contemporary climate can interact directly and indirectly with numerous biological and abiotic factors to influence reproductive success of wildlife species. We studied common loons, an iconic waterbird sensitive to timing and magnitude of waterlevel changes during the breeding season, using a before-after-control-impact design on large lakes in Voyageurs National Park (Minnesota, USA), to assess the effect of anthropogenic changes in hydroregime on their nesting success and productivity. We examined multiple competing a priori hypotheses in an information-theoretic framework, and predicted that magnitude of changes in loon productivity would be greater in the Namakan Reservoir, where water-level management was altered to mimic a more natural hydroregime, than in Rainy Lake, where management remained relatively unchanged. We determined outcomes from 278 nests during 2004–2006 by performing boat-based visits every 3–5 days, and measuring hydrologic, vegetative, and microtopographic covariates. Relative to comparably collected data for 260 total loon pairs during 1983–1986, productivity (chicks hatched/territorial pair) increased 95% in the Namakan Reservoir between the 2 time periods. Nest success declined in both lakes over the 2 study periods but less so in the Namakan Reservoir than in Rainy Lake. Flooding was a primary cause of nest failures (though second nests were less likely to flood). Nest predation appears to have increased considerably between the 2 study periods. Top-ranked models suggested that timing of nest initiation, probability of nest flooding, probability of nest stranding, and probability of nest success were each related to 2–4 factors, including date of initiation, timing of initiation relative to peak water levels, changes in the elevation of the nest edge, maximum waterlevel change between initiation and peak water levels, and maximum water-level change between initiation and nest outcome. The top model for all variables except stranding each garnered \u3e82% of total model weight. Results demonstrate that water-level management can be altered to benefit productivity of common loons. However, nuanced interactions between land-use change, invasive species, human development, recreation, climate change, and recovery of top predators may often complicate both management decisions and interpretation of water-level impacts on wildlife

Meeting Report: Methylmercury in Marine Ecosystems—From Sources to Seafood Consumers

Mercury and other contaminants in coastal and open-ocean ecosystems are an issue of great concern globally and in the United States, where consumption of marine fish and shellfish is a major route of human exposure to methylmercury (MeHg). A recent National Institute of Environmental Health Sciences–Superfund Basic Research Program workshop titled “Fate and Bioavailability of Mercury in Aquatic Ecosystems and Effects on Human Exposure,” convened by the Dartmouth Toxic Metals Research Program on 15–16 November 2006 in Durham, New Hampshire, brought together human health experts, marine scientists, and ecotoxicologists to encourage cross-disciplinary discussion between ecosystem and human health scientists and to articulate research and monitoring priorities to better understand how marine food webs have become contaminated with MeHg. Although human health effects of Hg contamination were a major theme, the workshop also explored effects on marine biota. The workgroup focused on three major topics: a) the biogeochemical cycling of Hg in marine ecosystems, b) the trophic transfer and bioaccumulation of MeHg in marine food webs, and c) human exposure to Hg from marine fish and shellfish consumption. The group concluded that current understanding of Hg in marine ecosystems across a range of habitats, chemical conditions, and ocean basins is severely data limited. An integrated research and monitoring program is needed to link the processes and mechanisms of MeHg production, bioaccumulation, and transfer with MeHg exposure in humans