Affect Hatching Success Research Articles

Persistent interactive effects of developmental salinity and temperature in Atlantic killifish (Fundulus heteroclitus)

Climate change alters multiple abiotic environmental factors in aquatic environments but relatively little is known about their interacting impacts, particularly in developing organisms where these exposures have the potential to cause long-lasting effects. To explore these issues, we exposed developing killifish embryos (Fundulus heteroclitus) to 26 °C or 20 °C and 20 ppt or 3 ppt salinity in a fully-factorial design. After hatching, fish were transferred to common conditions of 20 °C and 20 ppt to assess the potential for persistent developmental plasticity. Warm temperature increased hatching success and decreased hatch time, whereas low salinity negatively affected hatching success, but this was only significant in fish developed at 20 °C. Temperature, salinity, or their interaction affected mRNA levels of genes typically associated with thermal and hypoxia tolerance (hif1a, hsp90b, hsp90a, hsc70, and hsp70.2) across multiple developmental timepoints. These differences were persistent into the juvenile stage, where the fish that developed at 26 °C had higher expression of hif1a, hsp90b, hsp90a, and hsp70.2 than fish developed at 20 °C, and this was particularly evident for the group developed at both high temperature and salinity. There were also long-lasting effects of developmental treatments on body size after four months of rearing under common conditions. Fish developed at low salinity or temperature were larger than fish developed at high temperature or salinity, but there was no interaction between the two factors. These data highlight the complex nature of the developmental effects of interacting stressors which has important implications for predicting the resilience of fishes in the context of climate change.

Deformities and their potential control in larviculture of the European eel Anguilla anguilla

With the current assisted reproduction protocols, yolk-sac larvae of the European eel can be regularly produced. However, high mortality and deformity rates may exist during the first week after hatching with few larvae reaching the exogenous feeding stage. Recently, we suggested that larval survival could be impaired by pathogen pressure. Therefore, in this study, we tested the effects of antibiotics (rifampicin and ampicillin 50 mg L−1) and egg surface disinfection treatment (povidone iodine 25 ppm) on hatching success, larval survival and the occurrence of deformities in wild and feminized eels. Differences in egg quality aspects existed between offspring of wild and feminized eels. Eggs produced by the wild females were more buoyant than the ones released by the feminized eels. Larvae of the wild females hatched at higher rates and survived longer than the ones produced by the feminized eels. Disinfection treatment negatively affected hatching success and larval survival but the application of antibiotics improved larval survival. While larvae survived until 5 days post-hatch (dph) in the untreated controls, larvae continued to survive up to 21 dph when treated with antibiotics. Despite the beneficial effects of antibiotics on larval survival, a wide diversity of deformities could be observed during early development of eels that have not been reported before. The deformity determination key for young eel larvae that is presented in this paper fills a gap in the knowledge about larval deformities during early ontogeny. The larvae showed pericardial oedemas, microcephaly, an enlarged-yolk sac, necrosis and notochord deformities. The treatment with antibiotics decreased the deformity rates although they remained high (75–85%). The causes behind each deformity need to be clarified in order to prevent them in future trials.

Effect of moisture, temperature, and maternal influence on the hatching, phenotype, and performance of hawksbill turtles Eretmochelys imbricata

Hawksbill turtles are considered Critically Endangered. An understanding of how nest microenvironment (moisture and temperature) and maternal characteristics can influence embryonic development, hatching success, phenotype, and hatchling performance is needed to ensure effective conservation management. We undertook controlled egg incubations at different temperatures and relative humidities. Additionally, we sampled temperatures at natural nests with data loggers, and relative humidity of the sand at nest depth, to determine the conditions that eggs experienced naturally. We varied relative sand humidity (RSH) percentages (30, 50, 75, and 100%) at a constant incubation temperature of 29.5°C. We also assessed constant temperature incubations at 25, 29.5, and 34°C with 75% RSH. Incubation at 29.5°C resulted in successful hatching (73.3%), whereas temperatures of 25 and 34°C prevented hatching. However, hatching in natural nests occurred even between 34 and 36°C, provided that eggs were exposed to these temperatures <20% of the entire period of incubation, and only towards the end of incubation. Controlled incubation at 30% RSH prevented hatching. RSH linearly affected hatching success, phenotype, and performance of hatchlings: eggs incubated at 100% RSH had the greatest hatching success and produced the heaviest, largest, and fastest hatchlings. RSH correlated positively with sand depth on the beach, so that ≥75% RSH is ensured at the average depth of natural nests (~39.2 cm), resulting in successful hatching (74.3 ± 34.7%). The controlled incubation showed that temperature and hydric conditions had the most significant impact on hatching success, hatchling phenotype (size and weight), and hatchling performance. Maternal characteristics, however, were slightly less important. These results suggest that the impact of moisture should be taken into consideration in hawksbill turtle conservation projects. The thermal and hydric environments experienced by developing embryos should also be considered when evaluating how climate change affects marine turtles.

Breeding and migration performance metrics highlight challenges for White-naped Cranes

Globally, habitat loss has been deemed a major threat to wetland bird populations. However, the underlying mechanism of population declines and variations in the birds’ vulnerability throughout their annual cycle is challenging to determine, yet critical for development of targeted conservation strategies. Over seven years, landscape water availability explained occupancy of breeding territories best when breeding performance, migratory performance, and annual survival of the White-naped Crane (Grus vipio) population in eastern Mongolia were studied. Also, the hatching success of eggs was positively correlated with water availability in addition to plant productivity. High ambient temperatures and large numbers of herder families (and hence more livestock) negatively affected hatching success. High water availability at Luan, a major stopover site increased migration speed during the cranes’ northbound migration to their breeding grounds. In contrast, when water conditions were favorable, the birds stayed longer at the stopover site during southbound migration. Increased human density reduced the use of the stopover site during northbound migration. Finally, cranes arrived early at the breeding grounds when ambient temperature was high in northeast Mongolia. Combining these findings with historical trends in key environmental factors on their breeding grounds explains the general decline observed in this population of cranes in recent decades. Extrapolating our findings with future climate predictions, the outlook seems poor unless urgent action is taken. Knowledge of the mechanisms underlying White-naped Crane population decline in eastern Mongolia identified in this paper should improve the effectiveness of these actions.

Developmental asynchrony might not reduce fitness in early life in painted turtles.

Synchronous hatching and emergence of turtles from nests may be adaptive in predator avoidance during dispersal. However, little is known about the phenotypic consequences of such synchrony or the generality of predator avoidance in driving the evolution of this trait. Colbert et al. (2010) found that less advanced embryos hatched early in the presence of more advanced sibs, sustaining a persistent reduction in neuromuscular function. In this study, we experimentally assessed the influence of such accelerated embryonic development on hatching success, winter survival, and survival during terrestrial dispersal from the nest. Although we predicted that shortened incubation periods would reduce survival, early-hatching individuals suffered no detectable fitness costs at any stage considered in this study. Incubation temperature did not affect hatching success, and offspring sex did not affect survival across treatment groups. Incubation regime influenced offspring body size and was negatively correlated with dispersal time, however, there was no effect on survival during winter or terrestrial dispersal. Lack of a detectable fitness cost in these key early-life stages associated with hatching synchrony is consistent with a single, predator avoidance origin for this trait and retention in C. picta and other derived turtles via phylogenetic inertia.

A novel function of egg burial: burying material prevents eggs rolling out of wind-swayed nests

Egg burial behaviour, that is, when parents bury the eggs with a layer of nest material during the egg-laying stage, has been described in various egg-laying animals. Several functions of egg burial have been described in animals with different life histories and breeding traits, but rarely reveal distinctive functions between sister species. In the polygamous Eurasian penduline tit, Remiz pendulinus , sexual conflict over care has been proposed to drive egg burial since, during egg laying, females hide eggs from males to prevent them abandoning the nest. Females then have the option to desert the clutch themselves and leave parenting to the male. However, in a congeneric species, the Chinese penduline tit, Remiz consobrinus , males have been seen with females in the nest at night, which indicates males know of the eggs’ existence. In this study, we investigated egg burial function in Chinese penduline tits and experimentally tested four hypothesized functions of egg-burying behaviour. (1) We found that egg burial is unlikely to play a role in sexual conflict resolution, as both males and females appeared to bury eggs during egg laying and both freely entered and roosted in the nests with eggs exposed at night. (2) Egg burial does not prevent nest parasitism, as no egg rejection or clutch abandonment was observed in clutches with model parasitic eggs. (3) Our results do not support the temperature regulation hypothesis since the temperature difference between buried and experimentally unburied eggs did not affect hatching success. (4) Notably, our results support the novel egg protection against wind hypothesis since the burying layer efficiently prevented the eggs from rolling out of wind-swayed nests. The difference our study found between the two Remiz species highlights that one behaviour, egg burial, can serve different evolutionary functions between closely related species. • We experimentally tested four functions of egg burial in wild Remiz consobrinus . • Egg burial did not function against brood parasitism or in resolving sexual conflict. • Burying layer regulates egg temperature, but this did not improve hatching success. • Burying material efficiently stops eggs from being blown out of wind-swayed nest. • One behaviour can fulfil different functions even in closely related species.

Incubating green turtle (Chelonia mydas) eggs at constant temperatures: Hatching success, hatchling morphology and post-hatch growth

Past studies applying constant-temperature incubation of eggs have involved all species of sea turtles, but rarely can we find a single one incubating eggs at three or more temperatures. Here, we incubated green turtle (Chelonia mydas) eggs from Ganquan Island, South China Sea, at five constant temperatures (26, 28, 30, 32 and 34°C) to determine hatching success, incubation length and hatchling phenotype at each test temperature and temperatures optimal for embryonic development. Temperature affected hatching success, incubation length and all seven examined hatchlings traits, and clutch origin affected three (head length, fore-flipper length and hind-flipper length) of the seven. Hatching success was lowest at 34°C and none of hatchlings hatched at this temperature was normal and survived over one week. The rate of embryonic development and the rate of post-hatch growth both were lowest at 26°C. Given that low survival and growth rates can translate into reduced individual fitness, we conclude that both 26°C and 34°C are unsuitable for incubation of C. mydas eggs. Post-hatch growth was fastest in hatchlings incubated at 30°C, and eggs of C. mydas incubated at temperatures around 30°C are more likely to produce mixed sexes. Accordingly, we conclude that temperatures within the range from 28°C to 32°C are generally optimal for embryonic development of C. mydas.

Landfast ice: a major driver of reproductive success in a polar seabird.

In a fast-changing world, polar ecosystems are threatened by climate variability. Understanding the roles of fine-scale processes, and linear and nonlinear effects of climate factors on the demography of polar species is crucial for anticipating the future state of these fragile ecosystems. While the effects of sea ice on polar marine top predators are increasingly being studied, little is known about the impacts of landfast ice (LFI) on this species community. Based on a unique 39-year time series of satellite imagery and in situ meteorological conditions and on the world's longest dataset of emperor penguin (Aptenodytes forsteri) breeding parameters, we studied the effects of fine-scale variability of LFI and weather conditions on this species' reproductive success. We found that longer distances to the LFI edge (i.e. foraging areas) negatively affected the overall breeding success but also the fledging success. Climate window analyses suggested that chick mortality was particularly sensitive to LFI variability between August and November. Snowfall in May also affected hatching success. Given the sensitivity of LFI to storms and changes in wind direction, important future repercussions on the breeding habitat of emperor penguins are to be expected in the context of climate change.

Adult capture on the nest does not affect hatching success of masked lapwing (

Abstract Context Capture, measurement, genetic sampling, ringing and flagging of shorebirds on their nests are standard techniques that underpin the study and conservation of these species. However, these techniques may reduce hatching success by compromising parental care or nest crypsis, thereby negatively influencing results, study populations and bird welfare. Only a few studies that examine the effect of capture of shorebirds on subsequent egg hatching success are currently available. Aims To compare the hatching success of masked lapwing (Vanellus miles) nests, at which adult capture and associated techniques (ringing, flagging and bleeding) have occurred, with nests at which these did not occur, on the fox-free Phillip Island, Victoria, Australia. Methods Hatching success of masked lapwings was monitored and compared between nests at which adult capture did, and did not, occur. Clutches were aged and age was included in our models to adjust for exposure of clutches to risks such as predators. Key results There was no difference in egg hatching success between nests at which capture occurred and those at which it did not occur: 138 chicks hatched from 178 eggs attended by adults that were captured (77.5% hatched); and 279 chicks hatched from 442 eggs attended by adults that were not captured (63.1%). Conclusion Trapping incubating lapwings using our existing protocols does not compromise egg hatching success, at least where there are no foxes present. Implications Studies of ground-nesting shorebird hatching success in relation to capture can usefully assess for adverse effects of the methods employed. We suggest that further examination of capture of lapwings at the nest be conducted in environments where foxes are present.

Assessing nest attentiveness of Common Terns via video cameras and temperature loggers

BackgroundWhile nest attentiveness plays a critical role in the reproductive success of avian species, nest attentiveness data with high temporal resolution is not available for many species. However, improvements in both video monitoring and temperature logging devices present an opportunity to increase our understanding of this aspect of avian behavior.MethodsTo investigate nest attentiveness behaviors and evaluate these technologies, we monitored 13 nests across two Common Tern (Sterna hirundo) breeding colonies with a paired video camera - temperature logger approach, while monitoring 63 additional nests with temperature loggers alone. Observations occurred from May to August of 2017 on Poplar (Chesapeake Bay, Maryland, USA) and Skimmer Islands (Isle of Wight Bay, Maryland, USA). We examined data respective to four times of day: Morning (civil dawn‒11:59), Peak (12:00‒16:00), Cooling (16:01‒civil dusk), and Night (civil dusk‒civil dawn).ResultsWhile successful nests had mostly short duration off-bouts and maintained consistent nest attentiveness throughout the day, failed nests had dramatic reductions in nest attentiveness during the Cooling and Night periods (p < 0.05) with one colony experiencing repeated nocturnal abandonment due to predation pressure from a Great Horned Owl (Bubo virginianus). Incubation appeared to ameliorate ambient temperatures during Night, as nests were significantly warmer during Night when birds were on versus off the nest (p < 0.05). Meanwhile, off-bouts during the Peak period occurred during higher ambient temperatures, perhaps due to adults leaving the nest during the hottest periods to perform belly soaking. Unfortunately, temperature logger data alone had limited ability to predict nest attentiveness status during shorter bouts, with results highly dependent on time of day and bout duration. While our methods did not affect hatching success (p > 0.05), video-monitored nests did have significantly lower clutch sizes (p < 0.05).ConclusionsThe paired use of iButtons and video cameras enabled a detailed description of the incubation behavior of COTE. However, while promising for future research, the logistical and potential biological complications involved in the use of these methods suggest that careful planning is needed before these devices are utilized to ensure data is collected in a safe and successful manner.

Predation risk affects egg mortality and carry over effects in the larval stages in damselflies

Abstract The non‐consumptive predator effect may incur physiological costs that affect growth and development and ultimately survival. While studies have shown that the effect can affect development and growth in organisms with complex life cycles, we have limited knowledge on the effect in the egg and early larval stage. Here, we used a laboratory experiment to examine how the presence of chemical cues, a non‐consumptive predator effect, from an aquatic predator, perch, affected hatching success of larvae in three species of damselfly, Ischnura elegans, Coenagrion pulchellum, and Enallagma cyathigerum. In addition, we examined how exposure to predation risk in the early larval stages affected growth in the late larval stages of I. elegans. We found that the presence of chemical predator cues (1) increased egg mortality in all three species, (2) caused earlier hatching of eggs in one species, no change in a second species and a delay in egg hatching in a third species. We also found that predator cues have the potential to cause a carryover effect from early larval stages to late larval stages in terms of larval growth rate. The addition of non‐consumptive predator cues in the form of fish water caused higher algal growth than in the control experimental containers, and we suggest that this algal growth has the potential to confound predator stress cues. Our results show that the non‐consumptive predator effects affect survival and growth, and hence they have the potential to affect predator–prey dynamics in natural systems. Future studies on such effects in aquatic systems should consider confounding stressors, such as algae, fungi, oxygen, and nutrients levels, that might come with the addition of predation cues in water and thus add additional stress.

Does the vicinity of the Black-Headed Gull colony (Chroicocephalus ridibundus) increase the breeding success of the Common Tern (Sterna hirundo) on the islands of the middle Vistula?

We conducted our study in the Common Tern colony (STH) located on an island in the middle Vistula River course, at the height of the city of Dęblin (km 393–394 of the waterway), in 2017. Our goal was to investigate some aspects of the biology and reproductive ecology of this species. Due to the fact that STH breeds both in single-species as well as in two- or multi-species colonies, in associations with Little Terns (Sternula albifrons), Black-Headed Gulls (Chroicocephalus ridibundus) (LAR) and/or Mew Gulls (Larus canus), we wanted to investigate whether the neighborhood of other species (in this case LAR) affected hatching success and chick survival in STH. Our results clearly show that the presence of breeding terns in the neighborhood of the LAR colony was not accidental and/or caused by the lack of space on the island and/or the possibility of nesting elsewhere. The height of nesting site, type of nesting habitat, clutch size, mean egg volume and mean egg mass of these STH pairs did not differ significantly from those that formed a single species colony, on the same island but several hundred meters away. However, STH nests in the neighborhood of the LAR colony were established much earlier and both the hatching success and chick survival of STH during the early-chick stage were twice as high. Thus, we can conclude that the LAR colony could provide an effective protection against predation of crows, magpies and gulls, dangers which accounted for the vast majority of STH nest failures in the year of our study.

Going back to the roots: finding a strategy for the management of nesting loggerhead sea turtles in New Caledonia

Incubation temperature plays a vital role in sea turtle life history because it influences embryonic growth, sex determination and hatchling attributes such as body size, residual yolk size, self-righting ability, crawling speed and swimming speed. For these reasons there is concern that predicted increases in air temperature, as a result of global warming, will increase nest temperatures and result in decreased hatching success, decrease or cease male hatchling production, and decreased hatchling quality. In a previous study examining incubation temperature at a loggerhead turtle (Caretta caretta) rookery located at La Roche Percée, New Caledonia, high nest temperatures and root invasion by beach morning glory (Ipomoea pes-caprae) were found to adversely affect hatching success and locomotor performance. In the current study, we relocated loggerhead turtle nests into shaded hatcheries. Shading nests decreased sand and nest temperatures and was predicted to increase male hatchling production slightly, but nest emergence success was decreased due to invasion of cottonwood (Hibiscus tiliaceus) roots into some nests. Using shaded structures is a viable and affordable management option to counteract the high sand temperatures found on some sea turtle nesting beaches, but these shade structures need to be located some distance from trees and other plants to ensure that root penetration into nests does not adversely affect nest emergence success.

Agri-environmental measures and the breeding ecology of a declining farmland bird

Agricultural intensification is a key cause of the population declines shown by many farmland bird species across Europe. Changes in land management through agri-environment schemes (AES) are frequently cited as the best tool to reverse these trends, to date however they have received mixed support. This study tested whether AES options in England that provide winter seed food or insect-rich foraging during the breeding season, were associated with improved breeding performance in tree sparrow, Passer montanus, and/or the formation of larger breeding colonies. Breeding attempts (n=428) representing 210 pairs of tree sparrow comprising 22 colonies were compared in Wiltshire, England in 2013 and 2014. The area of margin AES, an insect-rich habitat, was positively correlated with fledgling success per breeding attempt and per breeding pair. Colony size increased with increasing wild bird seed mix AES area, a winter seed food resource, but this option negatively affected hatching success and the number of fledglings produced per breeding attempt. The observed association between colony size and this habitat was expected given that wild bird seed mixtures provide important seed food resources for granivorous birds during winter. The negative correlation with fledgling success, on the other hand, requires further investigation to determine whether this relationship relates to a lack of invertebrate and seed food during the breeding period. These results highlight the importance of providing a suite of AES habitats that are appropriately located to deliver both overwintering and breeding requirements of target, declining farmland birds.

Triclosan exposure results in alterations of thyroid hormone status and retarded early development and metamorphosis in Cyprinodon variegatus

Thyroid hormones are critically involved in somatic growth, development and metamorphosis of vertebrates. The structural similarity between thyroid hormones and triclosan, an antimicrobial compound widely employed in consumer personal care products, suggests triclosan can have adverse effects on the thyroid system. The sheepshead minnow, Cyprinodon variegatus, is now used in ecotoxicological studies that have recently begun to focus on potential disruption of the thyroid axis by endocrine disrupting compounds. Here, we investigate the in vivo effects of exposure to triclosan (20, 50, and 100μgL−1) on the thyroid system and the embryonic and larval development of C. variegatus. Triclosan exposure did not affect hatching success, but delayed hatching time by 6–13h compared to control embryos. Triclosan exposure affected the ontogenetic variations of whole body thyroid hormone concentrations during the larval phase. The T3 peak around 12–15 dph, described to be indicative for the metamorphosis climax in C. variegatus, was absent in triclosan-exposed larvae. Triclosan exposure did not produce any deformity or allometric repatterning, but a delayed development of 18–32h was observed. We conclude that the triclosan-induced disruption of the thyroid system delays in vivo the start of metamorphosis in our experimental model. We observed a global developmental delay of 24–45h, equivalent to 4–7% prolongation of the developmental time in C. variegatus. The costs of delayed metamorphosis can lead to reduction of juvenile fitness and could be a determining factor in the outcome of competitive interactions.

Life Stage Sensitivity of a Freshwater Snail to Herbicides Used in Invasive Aquatic Weed Control

Invasive aquatic plants like hydrilla (Hydrilla verticillata) threaten native species in many ways, ultimately degrading overall habitat quality and quantity. Aquatic herbicides are often chosen as a control and management strategy, but few peer-reviewed studies address their effects on non-target organisms, especially native freshwater mussels and snails. The aim of this study was to assess the life stage sensitivity of a rare snail, Somatogyrus virginicus (Lithoglyphidae), to two aquatic herbicides (dipotassium salt of endothall and fluridone). We collected adult snails, cultured their eggs on a vinyl card substrate, exposed adults and eggs in 96-h static-renewal experiments, and monitored eggs through hatching. Because fluridone is typically applied for ≥ 60 d, an additional treatment was exposed in staticrenewal through hatching (30 d total) to improve environmental relevance. Eggs present on the shells of adult snails were also monitored. Endpoints were adult survival and egg hatching success. Fluridone did not affect adult snail survival at concentrations up to 1500 µg/L, and in the test with eggs on vinyl cards, fluridone did not significantly delay (p = 0.12) or influence overall hatching success (p = 0.22), including in the 30-d exposure (Dunnett's p = 0.09). However, fluridone significantly delayed hatching of eggs on adult shells (p < 0.01) and reduced their overall hatching success (p < 0.01). The 96-h median effect concentration (EC50) for fluridone on hatching success of eggs on adults was 1334 µg/L (95% CI, 1215 – 1466 µg/L). For endothall, the adult 96-h median lethal concentration (LC50) was 223 mg/L (157 – 318 mg/L). Endothall negatively affected hatching success in both egg tests by delaying hatching (p < 0.01 in both tests) and by reducing overall hatching success (p = 0.04 for eggs on cards, and p < 0.01 for eggs on adults). The endothall 96-h EC50s for egg hatching success were 54.1 mg/L (95% CI, 35.6 – 82.2 mg/L; eggs on adults) and 83.4 mg/L (95% CI, 60.4 – 115.2 mg/L; eggs on cards). Neither herbicide had toxic effects to either life stage at concentrations typically prescribed for control of hydrilla (5 – 15 µg/L fluridone and 1 – 5 mg/L endothall). However, applying the minimum amount of herbicide needed for effective weed control is recommended for ensuring safety of non-target organisms.

Multi-Level Effects of Low Dose Rate Ionizing Radiation on Southern Toad, Anaxyrus [Bufo] terrestris.

Despite their potential vulnerability to contaminants from exposure at multiple life stages, amphibians are one of the least studied groups of vertebrates in ecotoxicology, and research on radiation effects in amphibians is scarce. We used multiple endpoints to assess the radiosensitivity of the southern toad (Anaxyrus [Bufo] terrestris) during its pre-terrestrial stages of development –embryonic, larval, and metamorphic. Toads were exposed, from several hours after oviposition through metamorphosis (up to 77 days later), to four low dose rates of 137Cs at 0.13, 2.4, 21, and 222 mGy d-1, resulting in total doses up to 15.8 Gy. Radiation treatments did not affect hatching success of embryos, larval survival, or the length of the larval period. The individual family variation in hatching success of embryos was larger than the radiation response. In contrast, newly metamorphosed individuals from the higher dose-rate treatments had higher mass and mass/length body indices, a measure which may relate to higher post-metamorphic survival. The increased mass and index at higher dose rates may indicate that the chronic, low dose rate radiation exposures triggered secondary responses. Additionally, the increases in growth were linked to a decrease in DNA damage (as measured by the Comet Assay) in red blood cells at a dose rate of 21 mGy d-1 and a total dose of 1.1 Gy. In conclusion, the complex effects of low dose rates of ionizing radiation may trigger growth and cellular repair mechanisms in amphibian larvae.

In vitro microarray analysis identifies genes in acute-phase response pathways that are down-regulated in the liver of chicken embryos exposed in ovo to PFUdA

Perfluoroundecanoic acid (PFUdA) is one of the most highly detected perfluoroalkyl compounds in wild bird tissues and eggs. Although PFUdA does not affect hatching success, many PFCs are known to impair post-hatch development and survival. Here we use microarrays to survey the transcriptional response of cultured chicken embryonic hepatocytes (CEH) to PFUdA for potential targets of PFUdA action that could lead to developmental deficiencies in exposed birds. At 1μM and 10μM PFUdA significantly altered the expression of 346 and 676 transcripts, respectively (fold-change>1.5, p<0.05, false discovery rate-corrected). Using functional, pathway and interactome analysis we identified several potentially important targets of PFUdA exposure, including the suppression of the acute-phase response (APR). We then measured the expression of five APR genes, fibrinogen alpha (fga), fibrinogen gamma (fgg), thrombin (f2), plasminogen (plg), and protein C (proC), in the liver of chicken embryos exposed in ovo to PFUdA. The expression of fga, f2, and proC were down-regulated in embryo livers (100 or 1000ng/g, p<0.1) as predicted from microarray analysis, whereas fibrinogen gamma (fgg) was up-regulated and plg was not significantly affected. Our results demonstrate the utility of CEH coupled with transcriptome analysis as an in vitro screening tool for identifying novel effects of toxicant exposure. Additionally, we identified APR suppression as a potentially important and environmentally relevant target of PFUdA. These findings suggest in ovo exposure of birds to PFUdA may lead to post-hatch developmental deficiencies, such as impaired inflammatory response.

Microbial community structure in sand on two olive ridley arribada nesting beaches, Playa La Flor, Nicaragua and Playa Nancite, Costa Rica

Microbial relative abundance, diversity and richness were assessed based on 16S rRNA gene-based TRF community analysis via terminal restriction fragment (TRF) analysis on two olive ridley turtle arribada nesting beaches in Central America, Playa La Flor in Nicaragua and Playa Nancite in Costa Rica. Arribada beaches have very high densities of egg clutches in small areas, and the sand contains numerous broken eggs due to turtles inadvertently disturbing previously laid clutches. The high organic content (broken eggs) in the sand causes microbial build up in clutches, which in return may affect hatching success. Phylotype relative abundance (fragment abundance) differed with nest density and distance from the water at both Playa Nancite and Playa La Flor. Higher relative abundance of certain bacterial species in high nest density areas may have contributed to lower hatching success. Bacterial diversity and richness increased with nest density and were higher in the zones closer to vegetation suggesting that bacterial diversity and richness may be important factors affecting hatching success of olive ridley eggs on these nesting beaches. To better conserve olive ridley sea turtles and manage egg harvest on arribada nesting beaches further studies should focus on identifying bacterial species that are pathogenic to turtle eggs and their effects on hatching success.

Embryonic Death Is Linked to Maternal Identity in the Leatherback Turtle (Dermochelys coriacea)

Leatherback turtles have an average global hatching success rate of ∼50%, lower than other marine turtle species. Embryonic death has been linked to environmental factors such as precipitation and temperature, although, there is still a lot of variability that remains to be explained. We examined how nesting season, the time of nesting each season, the relative position of each clutch laid by each female each season, maternal identity and associated factors such as reproductive experience of the female (new nester versus remigrant) and period of egg retention between clutches (interclutch interval) affected hatching success and stage of embryonic death in failed eggs of leatherback turtles nesting at Playa Grande, Costa Rica. Data were collected during five nesting seasons from 2004/05 to 2008/09. Mean hatching success was 50.4%. Nesting season significantly influenced hatching success in addition to early and late stage embryonic death. Neither clutch position nor nesting time during the season had a significant affect on hatching success or the stage of embryonic death. Some leatherback females consistently produced nests with higher hatching success rates than others. Remigrant females arrived earlier to nest, produced more clutches and had higher rates of hatching success than new nesters. Reproductive experience did not affect stage of death or the duration of the interclutch interval. The length of interclutch interval had a significant affect on the proportion of eggs that failed in each clutch and the developmental stage they died at. Intrinsic factors such as maternal identity are playing a role in affecting embryonic death in the leatherback turtle.