Good Bioindicator Research Articles

In vitro studies on the metal sensing capability of annelide hemoglobin

Many studies in the literature suggest that earthworms play an important role in the use and management of soils and are considered good bioindicators of environmental contamination by presenting changes in their behavior and even death when inserted in contaminated environments. In the current study we investigated the in vitro behavior of Amynthas gracilis hemoglobin (HbAg) against copper (Cu) and cadmium (Cd) in concentrations ranging from 0 to 100 µmol L-1, at pH values 5.0 and 7.0 by optical absorption, fluorescence emission, light scattering and circular dichroism techniques. Our results sugest that the HbAg undergoes oxidation in its heme group at both pH values. As from 30 µmol L-1 of copper in pH 7.0 HbAg is oxidized, dissociates and loses part of its secondary structure. In pH 5.0, it undergoes greater oxidation, also near 30 µmol L-1 but without secondary structures loss or dissociation. Regarding the metal cadmium, no significant changes were observed. The results indicate that HbAg has a potential for studies on copper biosensing.

Multiresidue Methods Analysis to Detect Contamination of Selected Metals in Honey and Pesticides in Honey and Pollen.

Honey, a natural food with a rich history, is produced by honeybees and other species of bees from nectar, other plant fluids, and honeydew of sap-sucking insects. During foraging, these bees may be exposed to plant protection products (PPPs), metals, and metalloids, potentially leading to residues in honey and hive products that could have a negative impact on human safety. Recognizing the lack of an appropriate methodology for pesticide contamination of honey and other hive products, this research aims to support the need for studies on residues in pollen and bee products for human consumption to establish safe maximum residue levels (MRLs) for consumers. A UHPLC-MS/MS residues method and a modified QuEChERS extraction were applied to simultaneously determine 237 pesticide residues in honey and pollen. The study in North Sardinia analyzed honey and pollen samples from six areas for pesticide residues and verified 27 heavy metals and metalloid residues using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The data obtained showed residues at levels close to the LOQ of the method, cycloate in a few samples of pollen, and dichlorvos, zoxamide, cycloate, and chlorantraniliprole in honey samples. All samples showed the absence of heavy metal contamination. Overall, no risk to human health was identified. The results of this study confirm that honey and pollen may be a good bioindicator of environmental contamination of a wide area surrounding honeybee hives.

Evaluation of enzymatic and non-enzymatic biomarkers of sublethal cadmium toxicity in the freshwater mussel (Unio tigridis).

Mussels are filter-feeding animals with a sedentary lifestyle and thus, they were accepted as good bioindicator animals to investigate environmental pollution. In this study, freshwater mussels (Unio tigridis) were exposed to cadmium (0, 30, 90, 270 µg Cd/L) for up to 21 days. Then, the responses of several biomarkers belonging to the antioxidant, osmoregulation and nervous systems, as well as the energy reserves of mussels were investigated. The animals were fed on laboratory-cultured algae (Chlorella vulgaris) during the experiments. Data showed that the exposure conditions did not cause mussel mortality within 21 days, though the levels of all biomarkers altered significantly (p < 0.05) compared to controls. Cadmium exposures significantly altered the activities of antioxidant enzymes in the digestive glands. Similarly, malondialdehyde (MDA) levels in the digestive glands significantly increased after cadmium exposures. Likewise, acetylcholinesterase (AChE) activity and Ca-ATPase activity in the muscle significantly decreased. There were decreases in Na-ATPase and increases in Mg-ATPase activities in the gill. The total energy reserves of mussels significantly decreased, especially at the higher cadmium concentrations. This study showed that environmentally relevant cadmium concentrations could alter the levels of biomarkers belonging to different metabolic systems, emphasizing their possible usage in evaluating metal contamination.

Standard Descriptors and Selected Biomarkers in Assessment of Posidonia oceanica (L.) Delile Environmental Response

Endemic Mediterranean seagrass Posidonia oceanica is highly endangered today as it lives in a narrow infralittoral zone intensely exposed to human impact. P. oceanica beds are especially endangered in the Adriatic Sea as the central and northern Adriatic could be considered as a naturally suboptimal area for P. oceanica growth. In this research, we used some standard descriptors of Posidonia meadows at different locations and depths and determined the biochemical parameters (phenolic compounds, photosynthetic pigments, and enzyme activities) in its leaves in order to find possible correlations among the measured parameters and environmental conditions. Photosynthetic pigments were shown to be sensitive biomarkers in the assessment of P. oceanica response to different light conditions, but more research is needed to elucidate the impact of other environmental factors. Overall, the results of this research show that the studied parameters are good bioindicators of a meadow’s environmental state, but it is necessary to analyze a number of diverse indicators together to properly characterize the state of a particular P. oceanica meadow. This approach would be very useful in the determination of P. oceanica conservation status, which is the first step towards improving monitoring protocols and implementing appropriate conservation measures.

Detection of milk's sheep quality indicators by studying the contamination of milk with some heavy metals in some areas of Hadramout Coast – Yemen

An experimental study was conducted with the aim of using sheep milk as bioindicators of environmental pollution for cadmium, lead and arsenic in some areas of Hadhramout coast in the period from November 2021 to March 2022, 45 samples of milk were collected from five areas of the Hadhramaut coast (Fowah, Al-Ghaleelah Thelah, Shaheer and Al-Khareebah). Cadmium and lead concentrations were measured by (FAAS), while arsenic concentrations were measured by (AAS- MHS 15). The results of study showed that the mean concentrations of cadmium, lead and arsenic in milk samples are 0.0087 ppm, 0.055 ppm and 0.105 ppm; respectively. Concentration of cadmium were higher than the permissible limit according to Europe Union and Codex Alimentarius milk 0.01 ppm in urban areas (Fowah, Al- Ghaleelah, and Shaheer). Lead concentration was found higher than the maximum permissible limit for Europe Union and Codex Alimentarius of lead in milk 0.02 ppm in areas (Fowah, Al- Ghaleelah, and Shaheer). Arsenic concentration was found higher than the maximum permissible limit for Europe Union and of arsenic in milk 0.1 ppm in Thelah area, While Al-Khareebah area was in maximum permissible limit Europe Union. The statistical results showed that there were significant differences between the average concentrations of cadmium, lead and arsenic at a significant level (p&lt;0.05) in milk samples in the different study areas. This study confirmed that sheep milk are good bioindicators for detecting environmental pollution with heavy metals. The study concluded that the main reason for the high concentrations of cadmium and lead in urban areas are human industrial activities, all process of combustion and industrial and agricultural wastes. The study recommends periodic monitoring and examination of heavy metals in the environment using bioindicators and identifying the main sources of their spread in the environment.

Species Composition and Diversity of Zooplankton in Chackferi Stream, Tarai Region, Uttarakhand, India

Present study deals with the analysis of species composition and diversity of zooplankton in Chackferi stream. For this investigation samples were collected by monthly intervals for a period of September 2020 to August 2022. A total of 28 species of zooplankton, belonging to 25 genera across 5 groups were identified such as Protozoa (6 species of 6 genera), Rotifera (10 species of 9 genera), Copepoda (7 species of 5 genera), Cladocera (3 species of 3 genera) and Ostracoda (2 species of 2 genera). Rotifera was the dominant group, comprising (36%) of the zooplankton community in Chackferi stream, followed by Copepoda (25%), Protozoa (21%), Cladocera (11%) and Ostracoda (7%). It was noticed that seasonal composition of zooplankton was highest during summer, moderate in winter and autumn and least in monsoon season. Zooplankton are also considered as a good bio-indicator to assess the pollution status of a stream. Presence of indicator species like Brachionus calyciflorus, Brachionus falcatus and Mesocyclops leuckarti reveals that the stream gets organically polluted and rapidly moving toward a eutrophic condition. Therefore, frequent monitoring and proper treatment should be applied for conservation of the stream and its ecosystem.

Which Fish Predators Can Tell Us the Most about Changes in the Ecosystem of the Pomeranian Bay in the Southwest Baltic Proper?

The results of our preliminary studies indicated that the diets of predatory fishes can be bioindicators of faunistic changes in ecosystems and indirectly of changes taking place in aquatic environments in the Pomeranian Bay. We examined the diet composition of top predators Gadus morhua, Sander lucioperca, Perca fluviatilis, and the mesopredator Neogobius melanostomus. The diet composition of the perch, pikeperch, and round goby in the Pomeranian Bay was analyzed for the first time. Our findings indicated that perch, an euryphagous species, is the best potential bioindicator because it is present in the area studied most of the year and has a low to moderate feeding index (FI). Baltic cod, also an euryphagous species, could be a good bioindicator in the areas where it is abundant and occurs frequently, but not in the Pomeranian Bay, where it is caught mainly in the fall. Round goby, which is present in the area studied and had a low FI, is a stenophagous species that preys mainly on benthic species, while pikeperch had a very high FI and the least number of prey species in its diet. The results of trophic interaction analysis among the predators analyzed and their non-native/invasive prey are also provided.

Availability of Using Honeybees and Hive Products as Bioindicators of Ambient Pesticide Exposure in Taiwan.

Honeybees and hive products could be used as bioindicators of pesticide exposure in surrounding areas, but the associations have rarely been examined. We collected samples of bees, hive products and environmental dust from 12 apiaries during the blooming season in eastern Taiwan and assessed the relationships between pesticides in apiarian samples and the environment. Samples were analyzed for 14 pesticides using gas or liquid chromatography coupled with mass spectrometry. Sick bees, dead bees, bee pollen, beeswax and environmental dust in the outer rings (>150 m) surrounding the apiaries were contaminated with high levels of pesticides (mean concentration: >270 ng/g in total). In terms of concentrations of all pesticides, insecticides, herbicides and fungicides, most apiarian sample matrices were significantly correlated with environmental dust within a range of 2.5 km (ρ > 0.6, p < 0.05), suggesting their potential as bioindicators. Of those apiarian matrices with high contamination contents, dead bees or beeswax may be a good bioindicator for all pesticides but not for herbicides, because of the insignificant correlation with environmental dust (ρ < 0.5). For all types of pesticides, we recommend sick bees and bee pollen as choices for bioindicators, because of their high contamination levels for detection and complete representativeness of the environment.

Deciphering the importance of morphological aspects in drought tolerance in eucalyptus progenies

Water limitation is one of the factors that most impact plant growth and productivity, especially for Eucalyptus. For commercial eucalyptus plantations to develop properly, it is essential to select clones with drought-tolerant characteristics, especially in areas with low rainfall and well-defined dry periods. Accordingly, climate change, mainly related to increases in mean annual temperature, can lead to a more severe water deficit and ultimately harm plant development. Thus, the identification of indicators related to climatic variables enables the selection of clones with drought tolerance characteristics. Here, we used 27 families of eucalyptus progenies from crosses of plants with previously selected characteristics associated with drought tolerance, which were planted in a region characterized by high water deficiency. Sample harvesting was performed at 6, 18, and 30 months after planting, at the end of natural drought cycles. Meteorological data coupled with physiological analyses allow the early selection of Eucalyptus clones that are better able to tolerate recurrent drought events. Specific leaf area (SLA), leaf area (LA), length (L), width (W), and leaf water potential (ΨL) were analyzed. The parameters SLA, LA, and ΨL proved to be good bioindicators of Eucalyptus drought tolerance. Specific clones and progenies (e.g., GG2673, VM1, GG1923, GG1980, GG3389XGG4302, GG918XVS62, AEC2034xLR831, I3000XVM1, VM4XCAM, and VM1xVM4) were characterized by physiological adjustments and showed higher average annual volumetric increment (IMAvol) values and were assumed as genetic materials with potential drought tolerance.

Evaluation of Catalase Activity, Gill Histology and Genotoxic Effects of Cadmium in Tilapia (Oreochromis Niloticus) Fingerlings

This research was designed to assess the toxicity of cadmium (Cd), and its effects on catalase (CAT) activity, histology of gills and geno-toxicity of Oreochromis niloticus. The acute toxicity of Cd (96-h) for fish was computed as 56.021 mg/L (LC50) and 80.7336 mg/L (LC100) using Probit method. The inferences showed that catalase level was significantly (P&lt;0.05) lower in Cd treated O. niloticus as compared to control that was metal-stress free. It followed the order as: intestine&lt;gills&lt;muscles&lt;brain. Results of gills histology showed that Cd-exposure caused prominent damage to both primary and secondary lamella. The histological alterations included fusion and curling of secondary lamella, hyperplasia in secondary lamella, epithelial lifting, and aneurysm observed in gills. Geno-toxic results showed that a significant (p&lt;0.05) increase in micronuclei, de-shape and notched nuclei in erythrocytes of Cd-exposed O. niloticus was found as compared to control. The inferences of this study confirmed the genotoxic properties of Cd. This study will be helpful in understanding the histological and geno-toxic changes in fish body kept under Cd stress. This study will also help in the development of a specific approach to minimize the negative and genotoxic impacts of cadmium. Furthermore, tilapia can be used as a good bio-indicator for detecting toxic impacts associated with water pollution.

Influence of acute heat shock on antioxidant defense of tropical fish, Psalidodon bifasciatus

Psalidodon bifasciatus is a fish species sensitive to physical and chemical changes in water. It serves as a good bioindicator of temperature variations and is utilized in environmental monitoring studies in Brazilian rivers. The objective of this study was to evaluate antioxidant defense biomarkers in the heart, brain, and muscle of P. bifasciatus exposed to a 10 °C thermal increase. P. bifasciatus were collected and divided into a control group (21 °C) and groups subjected to thermal shock (31 °C) for periods of 2, 6, 12, 24, and 48h. Two-way ANOVA indicated that a 10 °C temperature increase caused oxidative stress in P. bifasciatus. This was evidenced by altered levels of lipid peroxidation (LPO), carbonylated proteins (PCO), and glutathione peroxidase (GPx) in the heart, catalase (CAT) and LPO in the brain, and LPO in the muscle. Principal component analysis (PCA) and integrated biomarker response (IBR) analysis indicated that, compared to the heart and muscle, the brain exhibited a greater activation of the antioxidant response. Sensitivity analysis indicated that the muscle was the most sensitive organ, followed by the brain and heart. Our results indicate that the stress response is tissue-specific through the activation of distinct mechanisms. These responses may be associated with the tissue's function as well as its energy demand. As expected, P. bifasciatus showed changes in response to thermal stress, with the brain showing the greatest alteration in antioxidant defenses and the muscle being the most sensitive tissue.

Higher early than late-season residue load of pesticides in honey bee bread in Slovakia

Bees are often exposed to pesticide residues during their foraging trips in agricultural landscapes. The analysis of in-hive stored pollen reflects the spectrum of visited plants and can be almost used to link the exposure to pesticides.In the current study, bee bread samples were collected in May and July from 17 sites located in southern Slovakia. Samples were analysed using a multi-residue pesticide analysis method for a broad spectrum of active substances and microscopic for pollen identification.Our results revealed a bee bread contamination with 19 different active substances, with fungicides being predominant. Sixteen of them are authorized in the EU, but chlorpyrifos, chlorpyrifos-methyl, and chloridazon are not. The highest concentrations for pendimethalin (1400 µg/kg), fluazifop-butyl (640 µg/kg), fenpropidin (520 µg/kg), fluopyram (130 µg/kg), and difenoconazole (95 µg/kg) were detected. The total residue load in bee bread sampled in the early season (May) was significantly higher than in the late season (July). The mean residue load of insecticides analysed in July comprised 46% of May’s load, which is alarming due to the importance of bee bread in the diet for winter-rearing bees. Moreover, results from both sampling periods showed that fungicides were positively associated with plant families Apiaceae and Papaveraceae and herbicides with Aceraceae, Salicaceae, and Brassica-type/Brassicaceae.Hence, bee bread can be considered a suitable matrix and a good bio-indicator reflecting honey bee exposure to pesticides over the season.

Ecotoxicological consequences of urbanization: A multi-biomarker approach to assessing sewage treatment plant effects on free-living birds

Birds are good bioindicators of disturbance in the environment. They are present in different habitats and trophic levels. In addition, rapid urbanization has led birds to use cities as shelter and for seeking food resources. Sewage treatment plants (STPs) are suitable locations for free-living birds within cities. However, few studies address the impacts of emerging pollutants from sewage treatment plants on wild birds. In this sense, the aim of this study was to analyze the genotoxic, mutagenic, and immunological impacts from metal and pollutant exposure on free-living birds collected at a STP. For comparison, birds were collected in a preserved environment, the Silvania National Forest (FLONA). To achieve this, we used non-destructive biomarkers sensitive to environmental changes. Birds were collected in both environments using mist nets. After collection, birds were weighed, measured, species-identified, and released. Blood was collected for comet assay, micronucleus test, and leukocyte profile, while feathers were collected for metal concentration analysis. Water physicochemical parameters were measured at both sites, and water samples were collected for metal analysis. Our results demonstrated that birds collected at the STP exhibit a higher frequency of genotoxic damage and erythrocyte abnormalities, and increased immune response compared to FLONA birds. Traces of potentially toxic metals, such as Hg and As, were found in the birds feathers from both environments, raising concerns about metal contamination in both environments. Trophic guilds appear to respond similarly to exposure. The parameters and metals found in the water reflect environmental characteristics and may be influencing pollutant availability. Finally, despite the advancement of our findings, studies linking these damages to detrimental effects on behavior and reproduction are encouraged.

The Mesoamerican giant toad (&lt;em&gt;Rhinella horribilis&lt;/em&gt;) as bioindicator of vegetation degradation in a tropical forest

Identifying species that can serve as bioindicators of environmental quality is essential for monitoring the anthropogenic impact. Common and widespread species can be ideal bioindicators due to their abundance and easy monitoring, but a confirmation of their differential responses as a function of habitat perturbation is needed. Because amphibians are known as good bioindicators of environmental perturbation, we conducted this work to identify whether a common, generalist amphibian species, the Mesoamerican giant toad (Rhinella horribilis), could serve as a bioindicator of environmental degradation in a tropical forest. We sampled toads in two areas of tropical forest that differed in anthropogenic degradation (primary vs. secondary forest), establishing in each of these areas two sections of the same surface area but differing in substrate (grass vs. sand). We analyzed toad abundance, sex ratio, body length and condition, and the amount and distribution across the body of ectoparasites (ticks). We analyzed 59 toads that were infested with 503 ticks. Based on a multi-model inference approach, the results suggested that toads were more abundant and had lower body condition in the secondary than in the primary forest. In the secondary forest, females were proportionally less abundant than males. The tick loads responded to an interaction of the body area with either the forest type or the substrate, with increased occurrence of ticks in toads from secondary forests and from grass sections. The differences found between the primary and secondary forests in sex ratio, toad abundance, body condition, and tick load across body regions are consistent with previous studies in other less common species of amphibians and thus posit R. horribilis as a good bioindicator of anthropic disturbance in this tropical forest.

Caesium-137 in the muscles of game animals in 2015-2022 - levels and time trend.

Radioactive caesium-137 occurring in the environment may be taken up by plants and animals and pose a trophic threat to humans. Game animals living in forest ecosystems are very good bioindicators of the level of environmental contamination by ionising radiation. The main species measurably exposed to caesium-137 are the wild boar (Sus scrofa), the roe deer (Capreolus capreolus), and the red deer (Cervus elaphus). The study determined the levels of Cs-137 in muscle samples of these game animals in 2015-2022. Using gamma radiation spectrometry, 858 samples of game animal muscle tissue were examined: 508 wild boar, 145 roe deer and 205 red deer samples. Concentrations of Cs-137 varied widely (from minimum detectable activity (MDA) values to over 4,000 Bq/kg). In 63.4% of cases, the obtained concentrations exceeded the MDA. The permissible limit (600 Bq/kg for food) was exceeded in nine wild boar muscle samples, whereas it was not even exceeded once in roe or red deer muscle. The average concentration in wild boar was three times higher than in roe and red deer and amounted to 42.84 Bq/kg. The highest concentration of Cs-137 in wild boar muscle was 4,195 ± 372.0 Bq/kg, in roe deer muscle it was 111.5 ± 12.50 Bq/kg, and in red deer muscle was 86.70 ± 3.470 Bq/kg. The seven years' data indicate that wild boar absorb the most caesium-137 among game animals. The concentrations of Cs-137 in the muscle of game animals in the years 2015-2022 were at a nearly constant level, a very slow diminution being noticeable over time in roe and red deer muscle.

Salvage Logging and Secondary Succession Promote Spider Diversity in Post-disturbance Stands in Western Germany

Abstract Climate change and biodiversity loss strongly affect ecosystems. In recent years, forests have suffered substantially from climate-induced disturbances resulting in bark beetle outbreaks in coniferous forests. In forest plantations, such disturbances often cause large-scale diebacks, which are frequently salvage-logged. However, the consequences of natural disturbances and subsequent management for forest biodiversity and ecosystem services within plantations are largely unclear. Because they comprise good bioindicators for forest alterations, we here investigated epigeal spider diversity and community composition of three post-disturbance management approaches in former spruce plantations in western Germany. Taxonomic diversity of spiders was significantly enhanced on salvage-logged and secondary succession compared with standing deadwood sites. Nevertheless, the latter provided a refuge for forest specialists, moisture and shade-loving as well as smaller species, whereas the other two management categories were mostly inhabited by larger spiders associated with open habitats. Because all three post-disturbance management approaches harbored highly distinct spider communities and divergent functional guilds, we propose the application of a variety of management approaches for bark beetle-affected spruce plantations. The resulting habitat heterogeneity will likely enhance the biodiversity of spiders and other taxonomic groups. Study Implications: Bark beetle outbreaks became severe disturbances in spruce plantations. The management of affected stands usually aims at mitigating economic losses, but within the current biodiversity crisis, it is increasingly important to consider ecological consequences. This study shows that salvage logging or secondary succession can increase spider taxonomic diversity, although forest species preferred standing deadwood sites. All management categories harbored highly distinct spider assemblages characterized by different ecological and functional guilds. Our results indicated that spider communities were influenced by canopy openness, microclimate, and competition rather than post-disturbance management. Therefore, management practices should include diverse approaches to foster many different spider assemblages.

Under pressure: Assessing the ecological boundaries of the epipelagic goose barnacle Lepas anatifera using ocean gliders and laboratory experiments

Epipelagic barnacles have been considered good bioindicators since they are abundant and broadly distributed but with apparent tolerance restrictions to temperature and salinity, and also bioaccumulate pollutants. However, Lepas anatifera was found attached to the oceanic gliders, thriving through drastic and unreported environmental fluctuations. This study aimed to assess the resistance and oxidative stress responses of L. anatifera collected from gliders and attached to floating litter to temperature, salinity, and pressure. Barnacles withstood all tested pressure, temperature, and salinity ranges, except the extreme salt concentration. The activities of antioxidant enzymes – catalase and superoxide dismutase – were significantly increased under high temperature, high pressure, and low salinity. Malondialdehyde levels significantly increased only under high pressure. In conclusion, L. anatifera can be considered resistant organisms to extreme environmental changes. However, the instauration of oxidative stress under certain circumstances makes them vulnerable to predicted future trends in marine environments.

Integrated biomarker responses in wild populations of the intertidal sea anemone Bunodosoma zamponii living under different anthropogenic pressures.

Bunodosoma zamponii is the most abundant anemone in Mar del Plata (Buenos Aires, Argentina). Given that the presence of persistent organic pollutants (organochlorine pesticides and PCBs) and the organophosphate pesticide chlorpyrifos has recently been reported in this species, two wild populations living under different anthropogenic pressures were studied and compared regarding basic aspects of their ecology and physiological response to oxidative stress. A population from an impacted site (Las Delicias, LD) and another from a reference site (Punta Cantera, PC) were monitored seasonally (spring, summer, autumn, and winter), for one year. Anemones from PC were larger and more abundant than those from LD for most sampling periods. During winter, glutathione-S-transferase and catalase activities were higher in LD. Moreover, protein content and antioxidant defenses were higher in anemones from PC during winter as well. Taking into account their ecology (size and abundance) and biomarker responses, the population from PC was comparatively healthier. Furthermore, such differences are in agreement with recent studies indicating a higher concentration of pollutants in anemones from LD (specially during the winter sampling). In this sense, considering that B. zamponii can bioaccumulate the aforementioned pollutants, its resilience to their presence, and the fact that biomarker response differed between sites, this species can be regarded as a proper sentinel species of environmental pollution. Overall, this anemone seems to be a good bioindicator to be considered in future biomonitoring and ecotoxicological studies.

Thermal sensitivity of Rhinella arenarum tadpole at low concentrations of dimethoate pesticides

One of the main causes of contamination of aquatic environments, which affects biotic communities, is the use of pesticides in agricultural regions. Amphibians are considered good bio-indicators of aquatic pollution, because they are one of the most susceptible groups to pollution. Several studies suggest that both pollution and climate change produce synergistic effects in amphibians which amplify the toxicity afecting survival, and malformations with an increase in temperature. We studied the sensitivity of sublethal concentrations of dimethoate in Rhinella arenarum tadpoles on two fitness related thermal traits including locomotor swimming performance and thermal tolerance limits (CTmax = critical thermal maximum and CTmin = critical thermal minimum). The locomotor performance of R. arenarum tadpoles decreased with increasing sublethal dimethoate concentrations up to ∼60 % at intermediates dimethoate concentration. The tadpoles showed a tendency to decrease their tolerance to high temperatures (CTmax) with increasing dimethoate concentration around ∼0.5 °C, however no significant differences were found among treatments. Similarly, tadpoles showed decreases in their cold resistance (CTmin) with dimethoate concentrations, around 1 °C the high concentrations of dimethoate. The increase of atypical climatic events, such as heat waves may put R. arenarum tadpoles at greater risk when exposed to dimethoate. Our results show that the sublethal concentrations of the dimethoate pesticide may affect the fitness and survival of the larvae of R. arenarum in natural, and seminatural enviroments.

Intracolony variability in winter feeding and migration strategies of Atlantic puffins and black-legged kittiwakes

Polar ecosystems are subjected to many stressors, including climate change, that impact their overall functioning. Seabirds are good bioindicators of these systems as they readily respond to changes in environmental conditions. To quantify how environmental changes affect their life history, data on seabird diet, spatial distribution and body condition are needed to reveal the underlying mechanisms. We explored possible drivers of the winter distribution of single-colony populations of Atlantic puffins Fratercula arctica and black-legged kittiwakes Rissa tridactyla, two of the most numerous seabird species in the North Atlantic. Based on carbon and nitrogen stable isotopic data from feathers moulted during winter migration, we identified three groups of Atlantic puffins and two groups of black-legged kittiwakes occupying different isotopic niches. We then used geolocator tracking data for the same birds to determine if these groups reflected parallel differences in the location of moulting grounds rather than differences in their diet. We found that the isotopic niches of the three Atlantic puffin groups likely resulted from their use of different habitats during winter moult. In contrast, the isotopic niches of the two black-legged kittiwake groups were more likely a result of differences in their diet, as both groups were distributed in the same area. These findings suggest that different winter feeding and/or migration strategies may play a role in shaping the body condition of individuals for their following breeding season. We discuss the role of environmental conditions encountered by seabirds during winter migration to further elucidate such intracolony divergence in strategies. As polar ecosystems experience rapid changes in environmental conditions, the approach presented here may provide valuable information for the development of effective conservation measures (taking both intra- and intercolony variability into account), and to better predict future impacts of climate change.