Health of herring gulls (Larus argentatus) in relation to breeding location in the early 1990s. II. Cellular and histopathological measures

Monitoring and assessment of population, reproductive, and health effects in colonial waterbirds breeding at contaminated Great Lakes sites in Michigan

Immunological, reproductive, and population endpoints were assessed in fish-eating birds during 2010-2019 in the Saginaw River and Bay and River Raisin Areas of Concern (AOCs) and Grand Traverse Bay, which are ecosystems historically contaminated with polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans. Reference sites were in the lower St. Marys River (herring gulls and Caspian terns), eastern Lake Superior (terns), and eastern Lake Huron (black-crowned night herons). Relative risk ratios for embryonic nonviability (from both infertility and mortality) in gull embryos were 2-3-fold higher than the reference site in both AOCs and Grand Traverse Bay. Twelve of 13 deformed embryos and chicks (e.g., crossed bills and gastroschisis) were observed at the contaminated sites. Productivity of 4-week-old tern chicks in Saginaw Bay was 35% lower than that at reference sites. In the River Raisin AOC, productivity of 4-week gull chicks was poor in 7 of 10 years. Numbers of breeding herring gulls decreased significantly in the River Raisin AOC, and breeding Caspian terns, a state-threatened species, declined in the Saginaw River and Bay AOC. The mean T cell-dependent phytohemagglutinin skin response was suppressed 50%-56% in gull chicks in both AOCs and Grand Traverse Bay, and 49% in terns and 33% in herons in Saginaw Bay. Antibody responses in gull chicks in the River Raisin AOC and Grand Traverse Bay were 1.6-2-fold lower than reference. Time trend analyses showed no significant improvements in reproductive and immune endpoints in either AOC or Grand Traverse Bay over the study period. Embryonic death increased with time in gulls in the lower Saginaw Bay, and antibody responses decreased in terns in the outer Saginaw Bay.

A decade of data and hundreds of analytes: Legacy and emerging chemicals in North American herring gull plasma

Between 2010 and 2021, 199 herring gull serum samples were collected from Lake Michigan, Lake Huron, and Lake Erie, including two Areas of Concern: Saginaw Bay and the River Raisin. They were analyzed for 21 polybrominated diphenyl ether congeners, 10 non-PBDE flame retardants, 85 polychlorinated biphenyls, 17 legacy organochlorine pesticides, and 36 per- and polyfluoroalkyl substances. Σ36PFAS, Σ85PCB, Σ21PBDE, and Σ17Pesticide concentrations comprised 41-74%, 17-50%, 3-4%, and 5-9% of the total concentration, respectively. Median concentrations of the chemical groups ranged from 81.5 to 129 ng/g ww for PFAS, 26.3-158 ng/g ww for PCBs, 4.26-8.89 ng/g ww for PBDEs, and 8.08-23.0 ng/g ww for pesticides. The regional concentrations of all four classes of compounds are significantly decreasing when sites are combined with halving times of 11.3 ± 4.8, 8.2 ± 4.3, 5.9 ± 3.1, and 8.3 ± 4.2 years for the Penta-BDE mixture, ΣDDTs, Σ85PCBs and Σ36PFAS, respectively. These results suggest that, while PFAS has emerged as the dominant group of chemicals in the plasma, legacy pollutants continue to represent a threat to herring gulls and wildlife in the Great Lakes basin. PCBs were the largest contributors to the chemical load in plasma of birds whose colonies are located near the River Raisin, and continue to pose a threat to herring gulls within the two Areas of Concern.

Diseases of the Avian Urinary System

Diseases of the renal system can be caused by infectious and noninfectious processes. Creating a relevant differential diagnosis for kidney disease in the live or dead bird requires a structured approach where the list of differentials is narrowed based on the signalment of the bird; its history, including its diet and management; physical findings; and other diagnostic findings. This article aims to provide the reader not only a list of the diseases that occur in birds but also the guidelines on when a disease should be considered in a differential.

Contamination of organohalogen chemicals and hepatic steatosis in common kingfisher (Alcedo atthis) breeding at a nature reserve near e-waste recycling sites in South China

Severe pollution of organohalogen compounds (OHCs) including PBDEs, PCBs and DDTs is demonstrated in e-waste recycling sites and metropolis in South China, but relatively little is known of their impacts on wildlife that inhabits nature reserves in this region, especially those located at the neighborhood areas of e-waste recycling sites. In the present study, PBDEs, PCBs and DDTs as well as liver histological changes were examined in common kingfisher breeding at a nature reserve (Shimentai National Nature Reserve, SNNR) near a notorious e-waste recycling site in South China. Mean ∑PBDEs (84.9 ng/g lipid weight), ∑PCBs (397 ng/g) and ∑TEQs (total toxic equivalent of coplanar PCBs, 2.68 ng/g) concentrations in kingfishers from SNNR were approximately 2-, 5-, and 4-fold higher than those detected in a reference population, respectively; suggesting contamination of the e-waste-derived OHCs in SNNR. Mean ∑DDTs concentration (2150 ng/g) in kingfishers from SNNR was also higher (~2-fold) than that from the reference samples. While ∑DDTs dominated the composition of the OHCs at both sampling sites, ∑PCBs was also important in kingfishers from SNNR, averaging 15% of ∑OHCs. Histological examination of the liver showed steatosis occurred in 60% of the kingfishers from SNNR. Birds with hepatic steatosis had significantly (p = 0.03) higher ∑TEQs than those without steatosis. Similar trends were also found for ∑PCBs and ∑DDTs, although it is not statistically significant. It therefore seems likely that the hepatic steatosis were associated with the relatively high body-burden of OHCs, although the possibility of other factors resulting in hepatic steatosis cannot be ruled out.

Post mortem findings and their relation to AA amyloidosis in free-ranging Herring gulls (Larus argentatus)

Since the late 1990s, high mortality and declining populations have been reported among sea birds including Herring gulls (Larus argentatus) from the Baltic Sea area in Northern Europe. Repeated BoNT type C/D botulism outbreaks have occurred, but it remains unclear whether this is the sole and primary cause of mortality. Thiamine deficiency has also been suggested as a causal or contributing factor. With this study, we aimed to investigate gross and microscopic pathology in Herring gulls from affected breeding sites in Sweden in search of contributing diseases. Herring gulls from Iceland served as controls. Necropsies and histopathology were performed on 75 birds, of which 12 showed signs of disease at the time of necropsy. Parasites of various classes and tissues were commonly observed independent of host age, e.g. oesophageal capillariosis and nematode infection in the proventriculus and gizzard with severe inflammation, air sac larid pentastomes and bursal trematodiasis in pre-fledglings. Gross and microscopic findings are described. Notably, amyloidosis was diagnosed in 93 and 33% of the adult birds from Sweden and Iceland, respectively (p<0.001), with more pronounced deposits in Swedish birds (p<0.001). Gastrointestinal deposits were observed in the walls of arteries or arterioles, and occasionally in villi near the mucosal surface. Amyloid was identified within the intestinal lumen in one severely affected gull suggesting the possibility of oral seeding and the existence of a primed state as previously described in some mammals and chickens. This could speculatively explain the high occurrence and previously reported rapid onset of amyloidosis upon inflammation or captivity in Herring gulls. Amyloid-induced malabsorbtion is also a possibility. The Herring gull SAA/AA protein sequence was shown to be highly conserved but differed at the N-terminus from other avian species.

Immunological and reproductive health assessment in herring gulls and black-crowned night herons in the Hudson-Raritan Estuary

Previous studies have shown inexplicable declines in breeding waterbirds within western New York/New Jersey Harbor between 1996 and 2002 and elevated polychlorinated dibenzo-p-dioxins and polychlorinated biphenyls (PCBs) in double-crested cormorant (Phalacrocorax auritus) eggs. The present study assessed associations between immune function, prefledgling survival, and selected organochlorine compounds and metals in herring gulls (Larus argentatus) and black-crowned night herons (Nycticorax nycticorax) in lower New York Harbor during 2003. In pipping gull embryos, lymphoid cells were counted in the thymus and bursa of Fabricius (sites of T and B lymphocyte maturation, respectively). The phytohemagglutinin (PHA) skin response assessed T cell function in gull and heron chicks. Lymphocyte proliferation was measured in vitro in adult and prefledgling gulls. Reference data came from the Great Lakes and Bay of Fundy. Survival of prefledgling gulls was poor, with only 0.68 and 0.5 chicks per nest surviving to three and four weeks after hatch, respectively. Developing lymphoid cells were reduced 51% in the thymus and 42% in the bursa of gull embryos from New York Harbor. In vitro lymphocyte assays demonstrated reduced spontaneous proliferation, reduced T cell mitogen-induced proliferation, and increased B cell mitogen-induced proliferation in gull chicks from New York Harbor. The PHA skin response was suppressed 70 to 80% in gull and heron chicks. Strong negative correlations (r = -0.95 to -0.98) between the PHA response and dioxins and PCBs in gull livers was strong evidence suggesting that these chemicals contribute significantly to immunosuppression in New York Harbor waterbirds.

Mercury levels and health parameters in the threatened Olrog's Gull (Larus atlanticus) from Argentina

Mercury (Hg) exposure was investigated through feathers of Olrog's Gull and related to health parameters in adults (hematocrit, total plasma proteins, morphometric measures, sex) and chicks (hematocrit, total plasma proteins, immunoglobulins G and M) from a colony located in estuary of Bahía Blanca, Argentina. Mercury concentrations were 5.50 ± 2.59 μg g⁻¹ (n = 44) in live adults, 1.85 ± 0.45 μg g⁻¹ (n = 45) in live chicks and 1.81 ± 0.41 μg g⁻¹ (n = 41) in dead chicks. Large differences were observed between live adults and live or dead chicks and small differences between live and dead chicks. In the adults, the sex of the birds was the variable that best explained Hg concentrations. Male birds had higher concentrations than females; this suggests that the clutch provides a sink for mercury during egg laying. Hg concentrations in both adults and live chicks were associated with higher hematocrits. This could be associated with upregulated erythropoiesis to compensate for increased rate of destruction of prematurely senescent, Hg-contaminated erythrocytes. Based on our results, on the levels of Hg pollution in the past in the study area, and on the dietary specialization of Olrog's Gull, we must be vigilant about potential negative effects of Hg pollution on this population and recommend continued monitoring on this threatened species.

Seabirds as indicators of aquatic ecosystem conditions: a case for gathering multiple proxies of seabird health

The use of seabirds as sentinels of the condition of aquatic ecosystems has been well-established. Large environmental perturbations to aquatic food webs (e.g., chemical contamination, overfishing, particulate pollution) have all been detected or monitored by tracking seabirds at colonies. However, seabirds may elicit more subtle, sublethal responses that can also be used to track ecosystem health, or the health of seabird populations. In this article, we advocate for field researchers to plan a priori to collect a broader suite of samples when handling seabirds, and to reach out for collaboration with specialists (e.g., parasitologists, wildlife veterinarians). Collectively, such efforts will greatly improve our ability to establish baseline physiological and chemical levels for seabirds, against which we can detect future changes in aquatic ecosystems.

An overview of dioxin-like compounds, PCB, and pesticide exposures associated with sexual differentiation of neuroendocrine systems, fluctuating asymmetry, and behavioral effects in birds

Dioxin, polychlorinated biphenyls (PCBs), and pesticides impact neural systems in birds due to interference with sexual differentiation. Early endocrine disrupting chemical (EDC) effects may delay maturation and have long-term effects on lifetime reproduction, especially in precocial birds that complete sexual differentiation prior to hatch. Semi-altricial and altricial species appear more resilient to EDC effects and show a gradient in sensitivity, especially in the neuroplastic song system. Embryonic steroid exposure occurs via maternally deposited steroids followed by embryo produced hormones; EDCs potentially affect these developing systems. As such, EDCs can impact lifelong fitness by acting on neural systems that regulate reproduction, metabolism, and behavior.

Health of herring gulls (Larus argentatus) in relation to breeding location in the early 1990s. III. Effects on the bone tissue

Health effects associated with the Great Lakes environment were assessed in adult herring gulls (Larus argentatus) in the early 1990s, including the size and quality of their bones. Femurs were excised from 140 individuals from 10 colonies distributed throughout the Great Lakes and 2 reference colonies in Lake Winnipeg (freshwater) and the Bay of Fundy (marine). Femurs of gulls from the Great Lakes differed from the freshwater or marine reference for 9 of 12 variables of size, composition, and strength assessed using peripheral quantitative computed tomography (pQCT) and biomechanical testing. Femurs of Great Lakes gulls were significantly smaller in length (-2.9%), periosteal circumference (-2.4%), and cross-sectional area (-5.4%) than freshwater reference birds. Femurs of the Great Lakes gulls had a lower significant cortical bone mineral content (-8.1%) and density (-2%) than the marine reference. A significant increase in the amount the bone could bend before it broke (+34%) and the energy required to break it (+44%) and a significant decrease (-16.3%) in stiffness during three-point biomechanical bending test were also detected in Great Lakes versus the freshwater gulls. These differences are indicative of impaired mineralization. When divided into high and low 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalent (TCDD-TEQ) colonies, the amount the bone could bend before it broke and the energy required to break it were significantly higher in the high TEQ colonies, but not high polychlorinated biphenyl (PCB) colonies. Breeding location and dietary choices of Great Lakes herring gulls in the early 1990s resulted in modulations of physiological processes that affected the size, mineralization, and biomechanical properties of bone.