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At least 1,531 records · Page 85Linked to original sources

USGS2023

Maximum likelihood estimator and nightly acoustic count values as weight of evidence of bat maternity activity

Since the spread of white-nose syndrome in North America, several bat species have shown precipitous declines in abundance and distribution. With lower netting detection probabilities for the currently threatened but proposed endangered northern long-eared bat ( Myotis septentrionalis ) and endangered Indiana bats ( Myotis sodalis ), determination of presence or absence for regulatory clearance often has shifted to the use of acoustic sur- veys. However, acoustic surveys are unable to differentiate between non-reproductive individuals versus a maternity colony. We used recorded nightly echolocation pass counts of bat species-specific probabilities with maximum likelihood estimator (MLE) scores to determine thresholds by cover type and reproductive period whereby the potential for northern long-eared bat or Indiana bat maternity colonies occurs. Where nightly MLE P- values were <0.05, mean predicted nightly pass counts were significantly higher in areas of known northern long-eared bat and Indiana bat maternity colonies versus sites that were in either species’ distribution but with no maternity activity known. Nightly pass counts (MLE P < 0.05) were higher for sites with observed maternity activity for both bat species across forest, forest-field edge, and riparian areas versus sites where no maternity activity was known. For northern long-eared bats, nightly pass counts were highest in the juvenile volancy period (after 15 July) whereas, for Indiana bats, nightly pass counts were highest in the lactation period (16 June to 15 July). Except for edge conditions for northern long-eared bats, a MLE P < 0.05 combined with nightly pass counts above thresholds developed from surveys at known maternity colony sites for both species may indicate potential presence of a maternity colony locally and provide a tool to more efficiently use targeted mist-netting for further determination.

eastern United States↗

USGS2000

Biomonitoring of Environmental Status and Trends (BEST) Program: Selected methods for monitoring chemical contaminants and their effects in aquatic ecosystems

This document describes the suite of biological methods of the U.S. Geological Survey- Biomonitoring of Environmental Status and Trends program for monitoring chemical contaminants and their effects on fish. The methods, which were selected by panels of experts, are being field-tested in rivers of the Mississippi River, Columbia River, and Rio Grande basins. General health biomarkers include a health assessment index based on gross observation; histopathological examination of selected organs and tissues; condition factor; and the heptosomatic and splenosomatic indices. Immune system indicators are plasma lysozyme activity and measures of splenic macrophage aggregates. Reproductive biomarkers include plasma concentrations of sex steroid hormones (17β-estradiol and 11-ketotestosterone) and vitellogenin, gonadal histopathology (including reproductive stage and, in females, gonadal atresia), and the gonadosomatic index. Indicators of exposure to polycyclic aromatic and polyhalogenated hydrocarbons are the H4IIE rat hepatoma cell bioassay (performed on solvent extracts of composite fish samples) and hepatic ethoxyresorufin- O -deethylase activity. Stable nitrogen isotope ratios are used to assess the trophic position of the fish and their exposure to sewage and other animal wastes. For each indicator we describe endpoint(s) and methods, and discuss the indicator?s value and limitations for contaminant monitoring and assessment.

Information and Technology Report↗

USGS1980

Breeding biology and relation of pollutants to black skimmers and gull-billed terns in South Carolina

The breeding biology and relation of pollutants to black skimmers ( Ryn chops niger ) and gull-billed terns ( Gelochelidon nilotica ) were investigated in South Carolina from 1969 through 1975. With few exceptions, the two species nested together in colonies located on barrier islands. We located 10 colonies, 7 of which were on the Cape Romain National Wildlife Refuge (Cape Romain); references were located that described nesting on seven other islands in South Carolina that no longer support colonies. Gull-billed terns nested from early May through July; the skimmers started later (late May) but also continued later (early September). Both species nested in areas subject to tidal flooding, and the two species persisted in nesting in several colonies despite intense predation by rats and gulls. Estimated reproductive success varied greatly from year to year and colony to colony; success in most colonies seemed low, particularly for the gull-billed tern. Residues of organochlorine pollutants in several eggs seemed of sufficient magnitude to induce adverse effects on reproductivity and eggshell thickness: however, the overall effect of organochlorines appeared negligible. Maximum numbers of nests located in a single year were 790 for the skimmer and 340 for the gull-billed tern: the total breeding population in South Carolina is unknown. Although nesting islands at Cape Romain and Deveaux Bank are sanctuaries for nesting birds, both species will continue to lose nesting habitat as additional sea islands are developed and inhabited by man.

South Carolina↗

USGS2012

Exposure and effects of perfluoroalkyl compounds on tree swallows nesting at Lake Johanna in east central Minnesota, USA

Tree swallow ( Tachycineta bicolor ) samples were collected at a reference lake and a nearby lake (Lake Johanna) in east central Minnesota, USA contaminated with perfluorinated carboxylic and sulfonic acids. Tissues were analyzed for a suite of 13 perfluoroalkyl compounds (PFCs) to quantify exposure and to determine if there was an association between egg concentrations of PFCs and reproductive success of tree swallows. Concentrations of perfluoroocatane sulfonate (PFOS) were elevated in all tree swallow tissues from Lake Johanna compared to tissues collected at the reference lake. Other PFCs, except for two, were elevated in blood plasma at Lake Johanna compared to the reference lake. PFOS was the dominant PFC (>75%) at Lake Johanna, but accounted for <50% of total PFCs at the reference lake. There was a negative association between concentrations of PFOS in eggs and hatching success. Reduced hatching success was associated with PFOS levels as low as 150 ng/g wet weight.

Minnesota↗

USGS1982

Oviposition and the plasma concentrations of LH, progesterone, and corticosterone in bobwhite quail (Colinus virginianus) fed parathion

Bobwhite quail were fed concentrations of parathion (0,50, 100, 200 or 400 p.p.m.) for 10 days. Food intake, body weight change, brain acetylcholinesterase activity, egg production, and ovary weight were reduced in a dose-dependent manner. In a second experiment, birds were fed 0, 25 or 100 p.p.m. parathion or pair-fed control food to equate consumption in the 100 p.p.m. group. Egg production was not affected in birds fed 25 p.p.m. or in the pair-fed group, but the daily time of oviposition was more variable than in the control group. Cessation of egg production, inhibition of follicular development, and reduced plasma LH concentration were observed in birds fed 100 p.p.m. parathion. These findings indicate that exposure to parathion can impair reproduction, possibly by altering gonadotrophin secretion.

Journal of Reproduction and Fertility↗

USGS2011

Sperm quality assessments for endangered razorback suckers Xyrauchen texanus

Flow cytometry (FCM) and computer-assisted sperm motion analysis (CASA) methods were developed and validated for use with endangered razorback suckers Xyrauchen texanus collected ( n =64) during the 2006 spawning season. Sperm motility could be activated within osmolality ranges noted during milt collections (here 167–343 mOsm/kg). We hypothesized that sperm quality of milt collected into isoosmotic (302 mOsm/kg) or hyperosmotic (500 mOsm/kg) Hanks' balanced salt solution would not differ. Pre-freeze viabilities were similar between osmolalities (79%±6 (S.E.M.) and 76%±7); however, post-thaw values were greater in hyperosmotic buffer (27%±3 and 12%±2; P =0.0065), as was mitochondrial membrane potential (33%±4 and 13%±2; P =0.0048). Visual estimates of pre-freeze motility correlated with total ( r =0.7589; range 23–82%) and progressive motility ( r =0.7449) by CASA and were associated with greater viability ( r =0.5985; P <0.0001). Count (FCM) was negatively correlated with post-thaw viability ( r =-0.83; P =0.0116) and mitochondrial function ( r =-0.91; P =0.0016). By FCM-based assessments of DNA integrity, whereby increased fluorochrome binding indicated more fragmentation, higher levels were negatively correlated with count ( r =-0.77; P <0.0001) and pre-freeze viabilities ( r =-0.66; P =0.0004). Fragmentation was higher in isotonic buffer ( P =0.0234). To increase reproductive capacity of natural populations, the strategy and protocols developed can serve as a template for use with other imperiled fish species, biomonitoring, and genome banking.

Reproduction↗

USGS2000

Tree recruitment and survival in rivers: Influence of hydrological process

The findings of a 14-year study of tree reproduction and survival in the Platte River, Nebraska, are presented. The study was initiated in 1985 to determine the causes and remedies of woodland expansion and channel narrowing, which have reduced potential roosting habitat for migratory avifauna such as the whooping crane and sandhill crane. A total of 296 relocatable sites, constituting some 600 plots with Populus and Salix seedlings, was selected and sampled within two reaches near Shelton and Odessa, Nebraska. The fate of some 37 000 tree seedlings was monitored within the plot network. Tree recruitment is controlled largely by stream flow in June. Populus and Salix produce large numbers of seedlings in the river bed in most years, indicating the potential for high rates of woodland expansion. On average, in only 1 year in 7 is stream flow in June high enough to preclude Populus and Salix recruitment. Seedling mortality is dominated by two environmental factors: summer stream flow pulses from thunderstorms, which erode or bury new germinants, and river bed restructuring by moving ice in winter. A third factor, seedling mortality by desiccation during summer droughts, does occur but at a low frequency. Plots of seedlings had extremely low survival rates over the course of the study. Forty-two per cent of the plots lost all seedlings by the first remeasurement (July to September), 36% by the second measurement (May), and 10% by the third remeasurement (July). Thus nearly 90% of the plots had lost all tree seedlings by the end of the first year. These results explain why the Platte River has come into dynamic equilibrium with respect to the balance between active channel and woodland area. Low rates of new woodland expansion are counterbalanced by erosion of established woodland. The demographic approach to studying ecohydrology can be adapted to monitor the effectiveness of prescribed flows as insurance against future narrowing. Flows prescribed at key times to raise seedling mortality rates are recommended to maintain or widen channels, rather than mechanical clearing of established woodland. Copyright ?? 2000 John Wiley & Sons, Ltd.

Hydrological Processes↗

USGS2020

Population ecology and spatial synchrony in abundance within and among populations of valley oak (Quercus lobata) leaf gall wasps

What factors drive population variability through space and time? Here we assess patterns of abundance of seven species of gall wasps in three genera occurring on the leaves of valley oaks ( Quercus lobata ) at 10 sites throughout this species' statewide range in California, from 2000 to 2006. Our primary goals were to understand the factors driving variability in gall abundance and to assess the extent of spatial synchrony in gall wasp communities at both large and small geographic scales. On the large, statewide scale, there was significant site‐to‐site variation in gall abundance, driven in all cases primarily by differences in mean maximum seasonal temperatures, and lesser year‐to‐year variation. In contrast, on the small, local scale, differences were more pronounced from year to year than from tree to tree, and were to some extent correlated with differences in acorn production, suggesting an interaction with the reproductive effort of hosts. Significant spatial synchrony was detected, particularly at the statewide scale, but in no case did synchrony decline significantly with distance, despite sites being up to 741 km apart. Variation in spatial synchrony was correlated with a number of exogenous factors, including seasonal weather conditions, the acorn crop at the statewide scale and soil phosphorus availability at the local scale; however, most variation in spatial synchrony in our analyses remained unexplained.

California↗

USGS2001

Changing abundance of Hexagenia mayfly nymphs in western Lake Erie of the Laurentian Great Lakes: Impediments to assessment of lake recovery?

After an absence of 40 years, mayfly nymphs of the genus Hexagenia were found in sediments of western Lake Erie of the Laurentian Great Lakes in 1993 and, by 1997, were abundant enough to meet a mayfly-density management goal (ca. 350 nymphs m —2 ) based on pollution-abatement programs. We sampled nymphs in western Lake Erie and Lake St. Clair, located upstream of western Lake Erie, to determine the importance of seasonal abundance and life-history characteristics of nymphs (e.g., emergence and recruitment) on density estimates relative to the mayfly-density management goal. Two types of density patterns were observed: (1) densities were relatively high in spring and gradually decreased through late summer (observed in Lake Erie and Lake St. Clair in 1997 and Lake St. Clair in 1999) and (2) densities were relatively high in spring, gradually decreased to mid summer, abruptly decreased in mid summer, and then increased between summer and late fall (Lake Erie and Lake St. Clair in 1998 and Lake Erie in 1999). Length-frequency distributions of nymphs and observations of adults indicate that the primary cause for the two density patterns was attributed to failed (first pattern) and successful (second pattern) reproduction and emergence of nymphs into adults in mid summer. Gradual declines in densities were attributed to mortality of nymphs. Our results indicate that caution should be used when evaluating progress of pollution-abatement programs based on mayfly densities because recruitment success is variable both between and within years. Additionally, the interpretation of progress toward management goals, relative to the restoration of Hexagenia populations in the Great Lakes and possibly other water bodies throughout the world, is influenced by the number of years in which consequtive collections are made.

International Review of Hydrobiology↗

USGS2018

Survival of whirling disease resistant rainbow trout fry in the wild: A comparison of two strains

Introduced pathogens can affect fish populations, and three main factors affect disease occurrence: the environment, host, and pathogen. Manipulating at least one of these factors is necessary for controlling disease. Myxobolus cerebralis , the parasite responsible for salmonid whirling disease, became established in Colorado during the 1990s and caused significant declines in wild Rainbow Trout Oncorhynchus mykiss populations. Attempts to re-establish Rainbow Trout have focused on manipulating salmonid host resistance. A Rainbow Trout strain known as GR × CRR was developed for stocking in Colorado by crossing a whirling-disease-resistant strain known as the German Rainbow Trout (GR) with the Colorado River Rainbow Trout (CRR). The GR × CRR fish exhibit resistance similar to that shown by GR, and survival and reproduction were expected to be similar to those of CRR. One disadvantage of stocking GR × CRR is that outcrossing and backcrossing could decrease resistance, and laboratory studies have indicated that this can occur. A potential disadvantage of stocking pure GR is lower survival due to domestication. To compare fry survival between the strains, a field experiment was conducted in 1.6-km reaches of nine Colorado streams. Each stream was stocked in August 2014 with 5,000 GR × CRR and 5,000 GR individuals. In October 2014, April 2015, and August 2015, apparent survival was assessed. Two laboratory predation experiments were also conducted. The field experiment revealed that short-term apparent survival was influenced by stream, and growth rate was influenced by strain and stream. However, after 12 months, there was no difference in apparent survival or growth rate between the GR and GR × CRR strains. Laboratory experiments showed that survival did not differ between the strains when confronted with Brown Trout Salmo trutta predation. Our results indicate that the GR strain is a viable option for stocking in streams where M. cerebralis is enzootic. Further evaluation is needed to determine whether GR fish will survive to maturity and reproduce.

Journal of Aquatic Animal Health↗

USGS2005

Effects of forest structure and composition on food availability for Varecia variegata at Ranomafana National Park, Madagascar

We present a summary of a long-term field study that examined the effects of forest disturbance on the availability of palatable fruit and its utilization by V. variegata. Forest structure and tree species composition were measured in three adjacent study areas, with different histories of disturbance, in Ranomafana National Park (RNP), Madagascar. V. variegata abundance was monitored by frequent encounters with resident groups and periodic censuses conducted along trails. Finally, the abundance of mature fruit in species used by V. variegata was scored monthly at representative trees at several locations. V. variegata abundance was most consistent in the least anthropogenically disturbed site, while no established lemur groups were observed in the heavily logged site for over a decade post-harvest. Lemur abundance was variable in the selectively logged site. The presence of select food trees, particularly specimens with voluminous crowns capable of producing abundant fruit crops, appears to be key to the establishment and expansion of V variegata groups. Our analysis of year-long fruit utilization revealed a high degree of preference for several species of trees. Two species exhibited mature fruit in a low percentage of stems but were available for a protracted period of time, while two additional species showed high intraspecific fruiting synchrony and were available for a shorter period of time. These contrasting phenologies, rather than the individual tree species, may be most important to V. variegata due to their coincident timing of fruit maturation with key lemur life-history events. Any disturbance-natural or anthropogenic-that disrupts the phenology cycles of food trees has the potential to impact lemur abundance and dispersion. Intense disturbances, such as heavy logging or severe cyclones, have long-lasting impacts on fruit production, while selective logging or moderate cyclonic windthrow cause more transient impacts. V. variegata is adapted to deal with an intrinsically erratic food supply by virtue of its reproductive biology and social behavior.

American Journal of Primatology↗

USGS2021

Fragmentation and streamflow metrics drive prairie chub (Macrhybopsis australis) occurrence in the upper Red River basin

Dam construction threatens global aquatic biodiversity by fragmenting stream networks and altering flow regimes. The negative effects of dams are exacerbated by increased drought periods and associated water withdrawals, especially in semi-arid regions. Stream fishes are particularly threatened owing to their mobile nature and requirement for multiple habitats to complete their life cycles. An understanding of relationships with fragmentation and flow regimes, particularly as coarse-scale (e.g. catchment) constraints on species distributions, is essential for stream fish conservation strategies. Prairie chub ( Macrhybopsis australis ) is a small-bodied minnow (Cyprinidae) with poorly understood ecology endemic to the North American Great Plains. Suspected declines in abundance and extirpations have resulted in conservation interest for prairie chub at state and federal levels. Prairie chub is thought to share its reproductive strategy with pelagic-broadcast spawning minnows (pelagophils). Freshwater pelagic-broadcast spawning fishes have been disproportionately affected by fragmentation and streamflow alteration globally. Relationships of prairie chub occurrence with coarse-scale fragmentation and streamflow metrics were examined in the upper Red River catchment. Occurrence probability was modelled using existing survey data, while accounting for variable detection. The modelled relationships were used to project the distribution of prairie chub in both a wet and dry climatic period. The probability of prairie chub occurrence was essentially zero at sites with higher densities of upstream dams, but increased sharply with increases in flow magnitude, downstream open mainstem, and flood duration. The projected distribution of prairie chub was broader than indicated by naïve occurrence, but similar in both climatic periods. The occurrence relationships are consistent with the hypotheses of pelagic broadcast spawning and represent coarse-scale constraints that are useful for identifying areas of the stream network with higher potential for finer-scale prairie chub conservation and recovery efforts. In addition to informing pelagophil conservation, the relationships are also applicable to pelagic-broadcast spawning fishes in marine environments.

Oklahoma, Texas↗

USGS2019

Climate and disturbance influence self-sustaining stand dynamics of aspen (Populus tremuloides) near its range margin

Species that are primarily seral may form stable (self-sustaining) communities under certain disturbance regimes or environmental conditions, yet such populations may also be particularly vulnerable to ecological change. Aspen (Populus spp.) are generally considered seral throughout the northern hemisphere, including P. tremuloides, the most widely distributed tree species in North America. Recent declines in aspen populations have occurred, especially along drought-sensitive margins of its range and where fire exclusion and herbivory have promoted community transition. However, aspen also forms stable stands, and examination of the mechanisms that influence persistence can offer conservation insights, especially where populations are vulnerable to changing climate or altered disturbance dynamics. We sampled tree age and stand characteristics of isolated aspen forests in the arid Great Basin (USA) to determine if: (1) aspen communities are more fire-dependent and seral or fire-independent and stable; (2) ungulate browsing inhibits aspen stability; and (3) temporal patterns of vegetative reproduction (i.e., ramet establishment or “suckering”) are correlated with climate. Aspen size and age class densities strongly fit negative exponential distributions, whether grouped geographically or by functional type, suggesting landscape-scale persistence. Continuous age distributions and high proportions of recruitment-sized to overstory trees suggest stability at stand-scales, with exceptions including stands with higher browsing pressure. Few stands had evidence of fire, and relationships between dead tree size and variability in live tree size suggest a lack of fire-dependency. Several five-year averaged climate variables and one sea surface temperature index were correlated with aspen ramet establishment densities over time, with strongest relationships occurring ~5 years prior to establishment year, often followed by inverse relationships ~1 year after. Indeed, aspen establishment density for a recent 41-year period was reliably reconstructed using antecedent climate conditions derived from a single drought index. Temporally synchronized aspen ramet establishment across the study region may be due to climate-driven storage of nonstructural carbohydrate reserves in clonal root systems later used for regeneration. Complex regeneration dynamics of these self-sustaining aspen stands, especially sensitivity to climate variability, suggest they may serve as harbingers of ecological change in the arid Great Basin and in other aspen populations near their range margin.

Ecological Applications↗

USGS2019

Considerations for maximizing the adaptive potential of restored coral populations in the western Atlantic

Active coral restoration typically involves two interventions: crossing gametes to facilitate sexual larval propagation; and fragmenting, growing, and outplanting adult colonies to enhance asexual propagation. From an evolutionary perspective, the goal of these efforts is to establish self‐sustaining, sexually reproducing coral populations that have sufficient genetic and phenotypic variation to adapt to changing environments. Here, we provide concrete guidelines to help restoration practitioners meet this goal for most Caribbean species of interest. To enable the persistence of coral populations exposed to severe selection pressure from many stressors, a mixed provenance strategy is suggested: genetically unique colonies (genets) should be sourced both locally as well as from more distant, environmentally distinct sites. Sourcing three to four genets per reef along environmental gradients should be sufficient to capture a majority of intraspecies genetic diversity. It is best for practitioners to propagate genets with one or more phenotypic traits that are predicted to be valuable in the future, such as low partial mortality, high wound healing rate, high skeletal growth rate, bleaching resilience, infectious disease resilience, and high sexual reproductive output. Some effort should also be reserved for underperforming genets because colonies that grow poorly in nurseries sometimes thrive once returned to the reef and may harbor genetic variants with as yet unrecognized value. Outplants should be clustered in groups of four to six genets to enable successful fertilization upon maturation. Current evidence indicates that translocating genets among distant reefs is unlikely to be problematic from a population genetic perspective but will likely provide substantial adaptive benefits. Similarly, inbreeding depression is not a concern given that current practices only raise first‐generation offspring. Thus, proceeding with the proposed management strategies even in the absence of a detailed population genetic analysis of the focal species at sites targeted for restoration is the best course of action. These basic guidelines should help maximize the adaptive potential of reef‐building corals facing a rapidly changing environment.

Ecological Applications↗

USGS2025

Not all spatially structured populations are metapopulations: Re-examining paradigms for a threatened shorebird

For at-risk species, understanding population vital rates is imperative for developing informed conservation strategies and population models. Managers often assume that species that are spatially distributed among patches of suitable habitat meet the criteria of a metapopulation. Metapopulation dynamics are determined not only by within-patch birth and death processes but also by between-patch dispersal movements of individuals that are infrequent but critical to maintaining population viability across space and time. To conserve and manage such species, an understanding of all these vital rates, including connectivity, is required. The degree to which the northern Great Plains piping plover ( Charadrius melodus ) breeding population functions as a metapopulation depends, in part, on the rate of movement among patchily distributed breeding areas. Here, we examined annual adult survival and breeding dispersal probabilities for 2582 individuals at two spatial scales within the northern Great Plains piping plover breeding population between 2014 and 2019. Inconsistent with a metapopulation structure, annual survival varied minimally among breeding regions but did vary across years. We also found that breeding dispersal probabilities were temporally variable, high, and unbalanced at both spatial scales examined, suggesting high connectivity in contrast to metapopulation dynamics. Further, we detected context-dependent effects of reproductive success on dispersal decisions. Individuals were more likely to disperse from the northern Missouri River to the US Alkali Wetlands following nest failure due to inundation or severe storms (including in the year prior to dispersal), whereas dispersal from the US Alkali Wetlands to the northern Missouri River decreased following successful nest attempts. Individuals also decreased dispersal from the US Alkali Wetlands to the northern Missouri River in response to renesting attempts in both the year of interest and the year prior to dispersal. Our results contradict the paradigm that northern Great Plains piping plovers are structured as a metapopulation and instead suggest a patchily distributed, likely panmictic, population. Our findings have implications for the conservation and management of this listed species and are also a general reminder that in the absence of robust knowledge of movement, spatial variation in birth and death processes across patches should not be conflated with a metapopulation structure.

Montana, North Dakota, South Dakota↗

USGS2025

The future of biocontrol in the Anthropocene: A review of climate change impacts on biocontrol agents and their hosts

Biological control, the practice of using one species (biocontrol agent) to control the population of another (a host or prey species, hereafter target), can be a successful method to reduce pest species in agricultural and natural systems worldwide. Successful biocontrol agents often share a deep evolutionary history with their targets that results in high target specificity and synchronized phenology. However, with rapidly changing climatic conditions, users of biocontrol agents have questioned how climate change will affect both well-established and more recent biological control relationships. Using a meta-analysis of data collected from a systematic literature review, we evaluated the evidence for the impact of changing temperatures on the efficacy of biocontrol agents and corresponding responses in their targets. Overall, most studies of climate change impacts on biocontrol agents take place in the laboratory and focus on arthropod agents that are parasitoids. Results from our meta-analysis reveal that changes in temperature are projected to impact biocontrol agents and their targets similarly, with no overall significant changes to biocontrol agent or target performance. However, our results also show that temperature responses vary widely across study systems, as illustrated by case studies showing both positive, neutral, and negative effects of temperature on biocontrol agent efficacy, as well as variation in responses across the three core biological control measures of success: survival, reproduction, and efficacy. Our work highlights important knowledge gaps including how climate change will affect both biocontrol agents and their targets simultaneously. Additionally, we find that most current studies of climate impacts examined temperature relationships, predominantly of agricultural biocontrol agents. Increasing the breadth of studies is crucial for understanding the potential for climate change to affect the success of current and future biological control programs.

Ecological Applications↗

USGS2023

Confirmation of significant sea turtle nesting activity on a remote island chain in the Gulf of Mexico

Globally, six of the seven sea turtle species are threatened or endangered and as such, monitoring reproductive activity for these species is necessary for effective population recovery. Remote beaches provide a challenge to conducting these surveys, which often results in data gaps that can hamper management planning. Throughout the summer of 2022, aerial surveys were conducted over the Chandeleur Islands in the Gulf of Mexico. Turtle crawls were photographed for subsequent review by 10 expert observers. Whenever possible, ground surveys were conducted, and samples of unhatched eggs or dead hatchlings were collected. A summary of historic reports of sea turtle nesting activity at this site was also compiled. On 11 days between May 4, 2022, and July 30, 2022, photographs of 55 potential sea turtle crawls were taken. Observers identified 54 of those as being made by a sea turtle. There was high-to-moderate certainty that 16 of those crawls were nests, that 14 were made by loggerheads, and that two were made by Kemp's ridleys. Observers were least certain of species identification when surveys were conducted during rainy weather. Genetic analyses based on mitochondrial and nuclear DNA were conducted on samples from five nests and those analyses confirmed that three nests were laid by Kemp's ridleys and two were laid by loggerheads. Historic records from the Chandeleur Islands substantiate claims that the Chandeleurs have supported sea turtle nesting activity for decades; however, the consistency of this activity remains unknown. Our aerial surveys, particularly when coupled with imaging, were a useful tool for documenting nesting activity on these remote islands. Future monitoring programs at this site could benefit from a standardized aerial survey program with a seaplane so trends in nesting activity could be determined particularly as the beach undergoes restoration.

Louisiana↗

USGS2024

Where east meets west: Phylogeography of the high Arctic North American brant goose

Genetic variation in Arctic species is often influenced by vicariance during the Pleistocene, as ice sheets fragmented the landscape and displaced populations to low- and high-latitude refugia. The formation of secondary contact or suture zones during periods of ice sheet retraction has important consequences on genetic diversity by facilitating genetic connectivity between formerly isolated populations. Brant geese ( Branta bernicla ) are a maritime migratory waterfowl (Anseriformes) species that almost exclusively uses coastal habitats. Within North America, brant geese are characterized by two phenotypically distinct subspecies that utilize disjunct breeding and wintering areas in the northern Pacific and Atlantic. In the Western High Arctic of Canada, brant geese consist of individuals with an intermediate phenotype that are rarely observed nesting outside this region. We examined the genetic structure of brant geese populations from each subspecies and areas consisting of intermediate phenotypes using mitochondrial DNA (mtDNA) control region sequence data and microsatellite loci. We found a strong east–west partition in both marker types consistent with refugial populations. Within subspecies, structure was also observed at mtDNA while microsatellite data suggested the presence of only two distinct genetic clusters. The Western High Arctic (WHA) appears to be a secondary contact zone for both Atlantic and Pacific lineages as mtDNA and nuclear genotypes were assigned to both subspecies, and admixed individuals were observed in this region. The mtDNA sequence data outside WHA suggests no or very restricted intermixing between Atlantic and Pacific wintering populations which is consistent with published banding and telemetry data. Our study indicates that, although brant geese in the WHA are not a genetically distinct lineage, this region may act as a reservoir of genetic diversity and may be an area of high conservation value given the potential of low reproductive output in this species.

Ecology and Evolution↗