The toxicity of diquat, endothall, and fluridone to the early life stages of fish

ABSTRACT While most aquatic herbicides have undergone some toxicity testing for effects on non-target aquatic organisms, little of this testing has been conducted on early life stages of gamefish found in lakes undergoing treatment. Commercial formulations of diquat, endothall, and fluridone were selected for acute toxicity testing using very early life stages of walleye (Stizostedion vitreum), largemouth bass (Micropterus salmoides), and smallmouth bass (Micropterus dolomieu). In addition, the rates of diquat photodegradation and uptake by sediment were determined. These results were used to predict diquat concentrations in lakes of various depths. The results of the toxicity tests were compared to the predicted concentrations. Diquat, with 96-h LC50s of 0.74-4.9 mg/L, was more toxic to these early life stages than endothall or fluridone, with 96-h LC50s of 16-130 mg/L and 1.8-13 mg/L respectively. The LC50s for endothall and fluridone were at least one order of magnitude greater than the labeled application concentrations. As the LC50s for diquat were very close to the predicted concentration, the safety margin for the use of diquat appears to be very small

Reproductive Failure of Landlocked Atlantic Salmon from New York's Finger Lakes: Investigations into the Etiology and Epidemiology of the “Cayuga Syndrome”

We describe a disease syndrome that afflicts larval, landlocked Atlantic salmon Salmo salar from Cayuga Lake, one of central New York's Finger Lakes. Mortality associated with the “Cayuga syndrome” is 98–100%. Death usually occurs between 650 and 850 centigrade degree-days after fertilization, approximately 2–4 weeks before yolk resorption is complete. Although there is minor temporal variation in the onset of the Cayuga syndrome in progeny from individual females, all sac fry eventually succumb. Incubation of embryos and sac fry under constant, ambient, or reduced temperature regimens slightly alters the degree-day timing of syndrome onset, but does not improve survival. Based on mortality rate, manifestation of the Cayuga syndrome has not changed in the past 10 years, even though incubation waters of varying chemistry and temperature have been used. Mortality of the negative control stocks used for these studies never exceeded 10% from hatching to first feeding. Findings from reciprocal crossbreeding experiments indicate the problem is associated with ova only. A noninfectious etiology is indicated by the lack of consistently identifiable fish pathogens from syndrome-afflicted sac fry and by the failure to transmit the condition horizontally. Suspect contaminants were eliminated as potential causative factors. Epidemiological studies on the viability of other Finger Lakes stocks indicate that Atlantic salmon from Keuka and Seneca lakes are also afflicted (100% mortality). yet those from Skaneateles Lake are not. The cause of this syndrome appears to be nutritional.This is the publisher’s final pdf. The published article is copyrighted by the American Fisheries Society and can be found at: http://www.tandfonline.com/toc/uahh20/current#.Ug5ocnfAF8E

Garrick_etal_2018b_Simulated_Data.zip

Simulated DNA sequence haplotype data sets associated with Garrick et al. Extending phylogeography to account for lineage fusion. J. Biogeography

Data from: Extending phylogeography to account for lineage fusion

Secondary contact between long isolated populations has several possible outcomes. These include the strengthening of preexisting reproductive isolating mechanisms via reinforcement, the emergence of a hybrid lineage that is distinct from its extant parental lineages and which occupies a spatially restricted zone between them, or complete merging of two populations such that parental lineages are no longer extant ("lineage fusion" herein). The latter scenario has rarely been explicitly considered in single-species and comparative phylogeographic studies, yet it has the potential to impact inferences about population history and levels of congruence. In this paper, we explore the idea that insights into past lineage fusion may now be possible, owing to the advent of next-generation sequencing. Using simulated DNA sequence haplotype datasets (i.e., loci with alleles comprised of a set of linked nucleotide polymorphisms), we examined basic requirements (number of loci and individuals sampled) for identifying cases when a present-day panmictic population is the product of lineage fusion, using an exemplar statistical framework—approximate Bayesian computation. We found that with approximately 100 phased haplotype loci (400 bp) and modest sample sizes of individuals (10 per population), lineage fusion can be detected under rather challenging scenarios. This included some scenarios where reticulation was fully contained within a Last Glacial Maximum timeframe, provided that mixing was symmetrical, ancestral gene pools were moderately to deeply diverged, and the lag time between the fusion event and gene pool sampling was relatively short. However, the more realistic case of asymmetrical mixing is not prohibitive if additional genetic data (e.g., 400 loci) are available. Notwithstanding some simplifying assumptions of our simulations and the knowledge gaps that remain about the circumstances under which lineage fusion is potentially detectable, we suggest that the recent release from data limitation allows phylogeographers to expand the scope of inferences about long-term population history

Deflating Trees: Improving Bayesian Branch-Length Estimates using Informed Priors

© 2015 © The Author(s) 2015. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For Permissions, please email: [email protected]. Prior distributions can have a strong effect on the results of Bayesian analyses. However, no general consensus exists for how priors should be set in all circumstances. Branch-length priors are of particular interest for phylogenetics, because they affect many parameters and biologically relevant inferences have been shown to be sensitive to the chosen prior distribution. Here, we explore the use of outside information to set informed branch-length priors and compare inferences from these informed analyses to those using default settings. For both the commonly used exponential and the newly proposed compound Dirichlet prior distributions, the incorporation of relevant outside information improves inferences for data sets that have produced problematic branch- and tree-length estimates under default settings. We suggest that informed priors are worthy of further exploration for phylogenetics