Tracking the History and Ecological Changes of Rising Double-Crested Cormorant Populations Using Pond Sediments from Islands in Eastern Lake Ontario

<div><p>In the Laurentian Great Lakes region, the double-crested cormorant (<i>Phalacrocorax auritus</i>) has seen a thousand-fold population increase in recent decades. These large colonies of birds now often conflict with socioeconomic interests, particularly due to perceived competition with fisheries and the destruction of terrestrial vegetation in nesting habitats. Here we use dated sediment cores from ponds on islands in eastern Lake Ontario that receive waste inputs from dense colonies of cormorants and ring-billed gulls (<i>Larus delawarensis</i>) to chronicle the population rise of these species and assess their long-term ecological impacts. Modern water chemistry sampling from these sites reveals drastically elevated nutrient and major ion concentrations compared to reference ponds not influenced by waterbirds. Geochemical tracers in dated sediment cores, particularly δ¹⁵N and chlorophyll-<i>a</i> concentrations, track waterbird influences over time. Fossil diatom assemblages were dominated by species tolerant of hyper-eutrophic and polluted systems, which is in marked contrast to assemblages in reference sites. In addition to establishing long-term ecological impacts, this multi-proxy paleoecological approach can be used to determine whether islands of concern have been long-term nesting sites or were only recently colonized by cormorant or ring-billed gull populations across the Great Lakes, facilitating informed management decisions about controversial culling programs.</p></div

Extended study site descriptions and methods; dating profiles from Sterols and stanols as novel tracers of waterbird population dynamics in freshwater ponds

Sterol and stanol methods, sediment core dating, total Pb profiles, and personal correspondenc

Sterol and stanol % abundances from Sterols and stanols as novel tracers of waterbird population dynamics in freshwater ponds

Data used in figures 2 and

Subfossil diatom assemblages and geochemical tracers from sediment cores.

<p>Data are shown for the high-impact ponds on (A) East Brother Island (EB) and (B) Pigeon Island (PGN), as well as from the reference sites on (C) False Duck Island (FD1) and (D) Main Duck Island (MD2). The cyst to diatom ratio (C:D), sedimentary δ¹⁵N (‰) and spectrally-inferred sedimentary chlorophyll-<i>a</i> (chl-<i>a</i>) concentrations (mg/g) are given to the right of each stratigraphy. All profiles are presented on the same scales, except the C:D ratio for PGN. Grey boxes at the bottom of each core indicate sediment intervals in which diatom remains were too sparse to be enumerated.</p

Cormorant impact and morphological characteristics of study ponds.

<p>Pond abbreviations are as follows: East Brother (EB), Pigeon (PGN), False Duck Pond 1 (FD1), and Main Duck Pond 2 (MD2). The arrival of cormorants to East Brother and False Duck is based on data from D.V.C. Weseloh (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134167#pone.0134167.s002" target="_blank">S1 Table</a>) and based on data from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134167#pone.0134167.ref017" target="_blank">17</a>] for PGN. Numbers for nests, as well as pond diameter and depth, are estimates made in the field at the time of sampling. Details of water chemistry sampling methods and dates are provided in the materials and methods section.</p><p>Cormorant impact and morphological characteristics of study ponds.</p

A map of eastern Lake Ontario near Kingston, ON.

<p>Study ponds (with name and impact level) are on East Brother Island (EB, high-impact), Pigeon Island (PGN, high-impact), False Duck Island (FD1, low-impact), and Main Duck Island (MD2, no-impact).</p

Water chemistry for impacted and reference sites.

<p>(A) Specific conductivity (μS/cm) in high-impact ponds in black and hashed (ponds EB and PGN, respectively), the low-impact pond (FD1) in grey, and the no-impact pond (MD2) in white. Major cations and anions are listed in the inset by decreasing concentration. (B) Major nutrients in three study ponds, including total unfiltered nitrogen (TN) concentrations (mg/L) and total unfiltered phosphorus (TP) concentrations (μg/L).</p

A comparison of the effect of CdCl2 and MgCl2 processing on the transport properties of n-CdS/p-CdTe solar cells and a simple approach to determine their back contact barrier height

<p>Data are presented as means ± SD. Sample sizes are indicated for each species (muscle, organ tissues). Monthly fish consumption limits (U.S. Environmental Protection Agency) are indicated for MeHg. The consumption limits are 12 meals/month (59–78 ppb), 8 meals/month (78–120 ppb) and 4 meals/month (120–230 ppb).</p

Participant characteristics (N = 71) of Kasabonika and Wapekeka First Nations based on wild food consumption frequency.

<p>WF1 (n = 28; ≤1 meal per month), WF2 (n = 22; <1 meal per week), and WF3 (n = 21; ≥1 meal per week). Data are presented as means (±SD) where appropriate.</p

Map showing Wapekeka and Kasabonika First Nations in northern Ontario, Canada (inset).

<p>Map showing Wapekeka and Kasabonika First Nations in northern Ontario, Canada (inset).</p