Timing and duration of stopovers affects propensity to breed, incubation periods, and nest success of different wintering cohorts of red knots in the Canadian Arctic during the Years 2009 to 2016

Burger, Joanna; Porter, Ronald R.; Niles, Lawrence J.; Newstead, David J.

doi:10.1016/j.envres.2022.114227

Cited by 3 publications

(2 citation statements)

References 41 publications

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“…Red knots and other shorebirds migrating through Delaware have only 2–3 weeks to eat enough crab eggs to nearly double their weight with fat to fuel their migration north to Arctic breeding grounds [ 31 , 32 , 33 , 34 ]. Extensive, multi-disciplinary studies have shown the clear relationship between abundance of horseshoe crab surface eggs, shorebird time on Delaware Bay, weight gain, and success on the breeding grounds [ 22 , 31 , 35 , 36 , 37 , 38 , 39 ].…”

Section: Introductionmentioning

confidence: 99%

Metal Levels in Delaware Bay Horseshoe Crab Eggs from the Surface Reflect Metals in Egg Clutches Laid beneath the Sand

Burger

2023

Toxics

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Understanding variations in metal levels in biota geographically and under different environmental conditions is essential to determining risk to organisms themselves and to their predators. It is often difficult to determine food chain relationships because predators may eat several different prey types. Horseshoe crab (Limulus polyphemus) eggs form the basis for a complex food web in Delaware Bay, New Jersey, USA. Female horseshoe crabs lay thumb-sized clutches of eggs, several cm below the surface, and often dislodge previously laid eggs that are brought to the surface by wave action, where they are accessible and critical food for migrant shorebirds. This paper compares metal and metalloid (chromium [Cr], cadmium [Cd], lead [Pb], mercury [Hg], arsenic [As] and selenium [Se]) concentrations in horseshoe crab eggs collected on the surface with concentrations in eggs from clutches excavated from below the sand surface, as well as examining metals in eggs from different parts of the Bay. The eggs were all collected in May 2019, corresponding to the presence of the four main species of shorebirds migrating through Delaware Bay. These migrating birds eat almost entirely horseshoe crab eggs during their stopover in Delaware Bay, and there are differences in the levels of metals in blood of different shorebirds. These differences could be due to whether they have access to egg clutches below sand (ruddy turnstones, Arenaria interpres) or only to eggs on the surface (the threatened red knot [Calidris canutus rufa] and other species of shorebirds). Correlations between metals in clutches were also examined. Except for As and Cd, there were no significant differences between the metals in crab egg clutches and eggs on the surface that shorebirds, gulls, and other predators eat. There were significant locational differences in metal levels in horseshoe crab eggs (except for Pb), with most metals being highest in the sites on the lower portion of Delaware Bay. Most metals in crab eggs have declined since studies were conducted in the mid-1990s but were similar to levels in horseshoe crab eggs in 2012. The data continue to provide important monitoring and assessment information for a keystone species in an ecosystem that supports many species, including threatened and declining shorebird species during spring migration.

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Section: Introductionmentioning

confidence: 99%

Metal Levels in Delaware Bay Horseshoe Crab Eggs from the Surface Reflect Metals in Egg Clutches Laid beneath the Sand

Burger

2023

Toxics

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“…While the shorebirds make very long migrations and stop at Delaware Bay to refuel on their way to breed farther north [ 19 , 20 , 21 , 22 , 23 ], laughing gulls nest nearby in salt marshes along New Jersey’s Atlantic coast and migrate south only to the Caribbean or Gulf Coast [ 18 ]. The shorebirds that stop over at Delaware Bay remain for only two to three weeks [ 24 , 25 ], while laughing gulls are present throughout the horseshoe crab spawning season. Horseshoe crab abundance and egg availability are linked to shorebird survival and fitness [ 26 , 27 , 28 , 29 ].…”

Section: Introductionmentioning

confidence: 99%

Bioaccumulation of Some Metals and Metalloids in Laughing Gulls (Leucophaeus atricilla): Increases in Mercury and Decreases in Selenium from 2019 to 2022/2023

Burger,

Feigin,

Fojtik

et al. 2023

Toxics

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The elements in blood normally reflect the levels in prey, indicating a recent exposure. Laughing gulls (Leucophaes atricilla) eat mainly horseshoe crab eggs (Limulus polyphemus) in the spring in Delaware Bay, New Jersey. The levels of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and selenium (Se) in the blood of laughing gulls foraging on crab eggs were examined in Delaware Bay to provide information on a species that is normally a generalist, and to determine if the levels of these elements were similar in 2019 and 2022/2023, were intercorrelated, and were related to those in crab eggs. Hg increased from 2019 (136 ± 31 ng/g) to 2022/2023 (473 ± 75 ng/g), while Cd and Se decreased. There were some significant correlations among elements and a close relationship between the element levels in blood and those in crab eggs collected in the same month (except for As). The levels differed between laughing gulls and three species of shorebirds for As and Cd. The elements in the blood of gulls and shorebirds should be similar because they eat mainly the same eggs in the same places. A significant proportion of laughing gull blood samples had levels of Hg and Se that were above the levels associated with adverse effects, which requires further examination.

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Some metals and metalloids in the blood of three species of shorebirds increase while foraging during two-week migratory stopover in Delaware Bay, New Jersey

Burger,

Feigin,

et al. 2023

Environmental Research

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Timing and duration of stopovers affects propensity to breed, incubation periods, and nest success of different wintering cohorts of red knots in the Canadian Arctic during the Years 2009 to 2016

Cited by 3 publications

References 41 publications

Metal Levels in Delaware Bay Horseshoe Crab Eggs from the Surface Reflect Metals in Egg Clutches Laid beneath the Sand

Metal Levels in Delaware Bay Horseshoe Crab Eggs from the Surface Reflect Metals in Egg Clutches Laid beneath the Sand

Bioaccumulation of Some Metals and Metalloids in Laughing Gulls (Leucophaeus atricilla): Increases in Mercury and Decreases in Selenium from 2019 to 2022/2023

Some metals and metalloids in the blood of three species of shorebirds increase while foraging during two-week migratory stopover in Delaware Bay, New Jersey

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