Bioavailable Nutrients (N and P) and Precipitation Patterns Drive Cyanobacterial Blooms in Missisquoi Bay, Lake Champlain

Anthropogenic activities release large amounts of nitrogen (N) and phosphorus (P) nutrients into the environment. Sources of nutrients include surface and sub-surface runoffs from agricultural practices with the application of chemical fertilizers and manure as well as combined sewer overflows (CSOs). Nutrient runoffs contribute to the eutrophication of aquatic ecosystems and enhance the growth of cyanobacteria. Precipitation is an important driving force behind the runoff of nutrients from agricultural fields into surrounding water bodies. To understand the dynamics between nutrient input, precipitation and cyanobacterial growth in Missisquoi Bay, Lake Champlain (Quebec), one location in Pike River (a major tributary into the bay) and four locations in Missisquoi Bay were monitored from April to November in 2017 and 2018. Biweekly water samples were analyzed using chemical methods and high-throughput sequencing of 16S rRNA gene amplicons. High concentrations of N and P were typically measured in April and May. Three major spikes in nutrient concentrations were observed in early and mid-summer as well as early fall, all of which were associated with intense cumulative precipitation events of 40 to 100 mm within 7 days prior to sampling. Despite the high concentrations of nutrients in the spring and early summer, the cyanobacterial blooms appeared in mid to late summer as the water temperature increased. Dolichospermum sp. was the major bloom-forming cyanobacterium during both summers. A second intense bloom event of Microcystis was also observed in the fall (October and November) for both years. Variation in the cyanobacteria population was strongly associated with inorganic and readily available fractions of N and P such as nitrites and nitrates (NOx), ammonia (NH3) and dissolved organic phosphorus (DOP). During blooms, total Kjeldahl nitrogen (TKN) and total particulate phosphorus (TPP) fractions had a substantial influence on total nitrogen (TN) and total phosphorus (TP) concentrations, respectively. The abundance of bacteria involved in the metabolism of nitrogen compared to that of phosphorus revealed the importance of nitrogen on overall microbial dynamics as well as CB formation in the bay. Our findings emphasize the combined influence of precipitation events, temperature and several bioavailable fractions of nitrogen and phosphorus on cyanobacterial bloom episodes.

Rapid genetic adaptation to recently colonized environments is driven by genes underlying life history traits

Background Uncovering the mechanisms underlying rapid genetic adaptation can provide insight into adaptive evolution and shed light on conservation, invasive species control, and natural resource management. However, it can be difficult to experimentally explore rapid adaptation due to the challenges associated with propagating and maintaining species in captive environments for long periods of time. By contrast, many introduced species have experienced strong selection when colonizing environments that differ substantially from their native range and thus provide a “natural experiment” for studying rapid genetic adaptation. One such example occurred when sea lamprey (Petromyzon marinus), native to the northern Atlantic, naturally migrated into Lake Champlain and expanded their range into the Great Lakes via man-made shipping canals. Results Utilizing 368,886 genome-wide single nucleotide polymorphisms (SNPs), we calculated genome-wide levels of genetic diversity (i.e., heterozygosity and π) for sea lamprey collected from native (Connecticut River), native but recently colonized (Lake Champlain), and invasive (Lake Michigan) populations, assessed genetic differentiation between all populations, and identified candidate genes that responded to selection imposed by the novel environments. We observed a 14 and 24% reduction in genetic diversity in Lake Michigan and Lake Champlain populations, respectively, compared to individuals from the Connecticut River, suggesting that sea lamprey populations underwent a genetic bottleneck during colonization. Additionally, we identified 121 and 43 outlier genes in comparisons between Lake Michigan and Connecticut River and between Lake Champlain and Connecticut River, respectively. Six outlier genes that contained synonymous SNPs in their coding regions and two genes that contained nonsynonymous SNPs may underlie the rapid evolution of growth (i.e., GHR), reproduction (i.e., PGR, TTC25, STARD10), and bioenergetics (i.e., OXCT1, PYGL, DIN4, SLC25A15). Conclusions By identifying the genomic basis of rapid adaptation to novel environments, we demonstrate that populations of invasive species can be a useful study system for understanding adaptive evolution. Furthermore, the reduction in genome-wide levels of genetic diversity associated with colonization coupled with the identification of outlier genes underlying key life history traits known to have changed in invasive sea lamprey populations (e.g., growth, reproduction) illustrate the utility in applying genomic approaches for the successful management of introduced species.

The Fall of Fort Ticonderoga

This chapter discusses Burgoyne’s successful seizure of Fort Ticonderoga, the vital American position that guarded southern Lake Champlain and Lake George approach to the Hudson River and, ultimately, Albany. The significant leadership failures by the American commanders, especially Major General Arthur St. Clair and Major General Philip Schuyler, is examined in some depth. A combination of American failures—in preparation, execution, and the retreat—and the competent British conduct of operations, including the establishing of artillery on Mount Defiance, something the Americans believed was impossible, is discussed. Improperly sited fortifications, failure to secure key terrain, and an incompetently planned and executed retreat, ensured American failure to hold the fortification.

Defeat, Retreat, Disgrace

This chapter discusses the military operations that took place in the immediate aftermath of the British capture of Fort Ticonderoga and its surrounding fortifications. The Battle of Hubbardton, during which the American rear guard, led by Ebenezer Francis and Seth Warner, stopped the British pursuit by Simon Fraser and Friedrich Riedesel and enabled the escape of St. Clair’s Ticonderoga garrison is discussed. In addition, the successful British water pursuit on the southern arm of Lake Champlain of the Americans who escaped Ticonderoga to Skenesborough on vessels, is examined as another failure of leadership. Finally, the British pursuit of American survivors and the action at Fort Anne is discussed.

The First Invasion

This chapter describes the first British invasion of New York via the historic Lake Champlain, Lake George, and Hudson River route in the autumn of 1776. It starts with General Sir Guy Carleton’s successful defense of Canada and repulse of the American attempt to seize Quebec. The increasingly fraught relationship between Carleton and Lord George Germain is also addressed as is the naval arms race between the Americans and the British. This race delayed Carleton’s offensive south on Lake Champlain more than the celebrated Battle of Valcour Island, and he was forced to abandon the offensive after he reached Crown Point, much to the dismay of his second-in-command, Lieutenant General John Burgoyne. This failed first invasion planted the seeds for a new plan created in part by Burgoyne.

“May Day, 2020”

“May Day, 2020” is a poem by Eli Clare, who is white, disabled, and genderqueer and lives near Lake Champlain in occupied Abenaki territory (currently known as Vermont) where he writes and proudly claims a penchant for rabble-rousing.

Achieving Sea Lamprey Control in Lake Champlain

The control of parasitic sea lamprey in Lake Champlain has been a necessary component of its fishery restoration and recovery goals for 30 years. While adopting the approach of the larger and established sea lamprey control program of the Laurentian Great Lakes, local differences emerged that shifted management focus and effort as the program evolved. Increased investment in lamprey assessment and monitoring revealed under-estimations of population density and distribution in the basin, where insufficient control efforts went unnoticed. As control efforts improved in response to a better understanding of the population, the effects of lamprey on the fishery lessened. A long-term evaluation of fishery responses when lamprey control was started, interrupted, delayed, and enhanced provided evidence of a recurring relationship between the level of control effort applied and the measured suppression of the parasitic sea lamprey population. Changes in levels of control efforts over time showed repeatedly that measurable suppression of the parasitic population required effective control of 80% of the known larval population. Understanding the importance of assessment and monitoring and the relationship between control effort and population suppression has led to recognition that a comprehensive, not incremental, approach is needed to achieve effective control of sea lamprey in Lake Champlain.

Evaluation of the FLake Model in ERA5 for Lake Champlain

Global model reanalyses of temperature and radiation are used for many purposes because of their spatial and temporal homogeneity. However, they use sub-models for lakes that are smaller than the model grid. This paper compares the simplified small-lake model, known as FLake, used in the European Centre global reanalysis known as ERA5, with observations made in and near Lake Champlain in northern Vermont. Lake Champlain is a challenging test for the ERA5 FLake model. The lake, which extends over several grid cells, is the lowest region at 30 m above sea level within complex mountain topography. The smoothing of the adjacent mountain topography means that the ERA5 grid cells containing the lake have higher mean elevations then 30 m, and this contributes to a small cool bias in FLake mid-summer temperatures. The seasonal cycle of FLake temperatures has a sharper peak than the observed lake temperatures. In winter, lake temperatures are close to 3°C, while the 30 m deep FLake mixed layer (ML) is near freezing. In May and June, FLake maintains a deep ML, while lake profiles are generally strongly stratified with peak temperatures near the surface several degrees above the model ML. One possible contributing reason is that inflowing river temperatures that are not considered by FLake are as much as 5°C above the lake surface temperature from April to June. The lake does develop a ML structure as it cools from the temperature peak in August, but the FLake ML cools faster and grows deeper in fall. We conclude that the vertical mixing in the FLake ML is stronger than the vertical mixing in Lake Champlain.