Urban environments often contain mosquito species that are responsible for transmitting medically important pathogens to humans. Large disturbance events, like hurricanes, can devastate large urban areas, especially in the tropics, however little data exist for how these storms affect vector populations. During September 2017 Hurricanes Irma (category 5) and Maria (category 4) passed in proximity to the island of Puerto Rico, U.S.A., causing significant damage to the built environment and significantly altering the abiotic environment including the removal of the plant canopy. We measured adult Aedes aegypti populations, the main vector of several pathogens, and larval containers across eight neighborhoods in San Juan, the capitol, that varied in socioeconomic status (SES) across eight sampling periods over 17 months following the storms. We also analyzed the nutrient content (%N, %C, C:N) and stable isotopes (δ15N, δ13C) from adults and isotopes from containers to assess how the nutrient environments changed post hurricanes. Mosquito population sizes were invariant throughout sampling, although more females were collected in lower SES neighborhoods that were more enriched in δ15N compared to higher SES locations. We did find that the storms altered the stoichiometric content of adults, with lower C:N values right after compared to a year later; larval containers showed an increase in δ15N through time. The lack of any interactive effects of the storms on specific neighborhoods suggests that Irma and Maria affected all locations equally, however, the storms altered the nutrient content of both adults and larval containers, a result with implications for pathogen transmission.
The federal Superfund site at New Bedford Harbor (Massachusetts, USA) is an example of an environment where pollution levels rose quickly and dramatically. Industrial waste containing polychlorinated biphenyls, heavy metals, and other organic pollutants was dumped into the harbor in the mid-20th century. The mummichog (Fundulus heteroclitus) is a widely distributed fish typically susceptible to polychlorinated biphenyl toxicity. However, the population in New Bedford Harbor is one of several that have evolved the ability to tolerate this category of toxicants. Constituents of the aryl hydrocarbon receptor system are linked to this adaptive pollution tolerance. Our population genetic analysis of 444 mummichogs from Massachusetts and Rhode Island estuaries using 55 SNP loci suggests that F. heteroclitus near New Bedford Harbor have large populations and restricted but meaningful levels of gene exchange among adjacent habitats. When comparing polluted to cleaner sites, we find strong evidence of genetic differentiation at a small geographic scale. Populations at the two most polluted sites form a genetically distinct cluster. Much of this differentiation is driven by allele frequency differences at loci associated with the aryl hydrocarbon receptor system. While allele frequencies at loci associated with pollution tolerance vary between clean and polluted habitats, putatively adaptive alleles are present at low frequency elsewhere in our study area.
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