Hatching Success Research Articles

The effects of dune plant roots on loggerhead turtle (Caretta caretta) nest success.

Sand dunes are supported by the extensive root systems of dune plants that anchor the dune and protect it from erosion. While all plants that grow on the dunes support their structure, invasive plants can outcompete the native and non-native dune plants for resources such as nutrients, sunlight, and space to grow. During the summer, sea turtles lay nests on beaches and near dunes; however, their eggs and hatchlings are at risk of destruction and entrapment by dune plant root penetration. Dune plant roots can penetrate sea turtle nest cavities, thus decreasing hatch success of the eggs and emergence success of the hatchlings. We aimed to determine how plant roots impact threatened loggerhead sea turtle (Caretta caretta) nests on Casey Key, Sarasota County, Florida, USA and to assess the factors affecting plant root invasion. Specifically, we determined the effect of plant roots on loggerhead sea turtle nest success, the extent of the impact of invasive plants over non-invasive plants on nests, and if the distance from the dune (barrier) affects whether roots will penetrate the nest. From July to August 2022, we excavated 93 nests to determine the extent of root penetration and identify associated plant species. This field campaign was supported by a long-term dataset (1987-2022) on loggerhead sea turtle nesting across the region. We found that root presence decreased hatch success by 21% and emergence success by 18%, compared to nests that lacked roots within the nest chamber. Nests closer to the dune were more likely to have a higher proportion of root damage and lower hatch and emergence success. This study helps advance understanding of how native and non-native plants affect sea turtle reproductive success and helps inform coastal management aimed at conserving threatened loggerhead populations.

Evaluation of the mosquitocidal efficacy of fluralaner, a potential candidate for drug based vector control

Vector control is a key intervention against mosquito borne diseases. However, conventional methods have several limitations and alternate strategies are in urgent need. Vector control with endectocides such as ivermectin is emerging as a novel strategy. The short half-life of ivermectin is a limiting factor for its application as a mass therapy tool for vector control. Isoxazoline compounds like fluralaner, a class of veterinary acaricides with long half-life hold promise as an alternative. However, information about their mosquitocidal effect is limited. We explored the efficacy of fluralaner against laboratory reared vector mosquitoes—Aedes aegypti, Anopheles stephensi, and, Culex quinquefasciatus. 24 h post-blood feeding, fluralaner showed a significant mosquitocidal effect with LC50 values in the range of 24.04–49.82 ng/mL for the three different mosquito species tested. Effects on life history characteristics (fecundity, egg hatch success, etc.) were also observed and significant effects were noted at drug concentrations of 20, 25 and 45 ng/mL for Ae. aegypti, An. stephensi, and, Cx. quinquefasciatus respectively. At higher drug concentration of 250 ng/mL, significant mortality was observed within 1–2 h of post blood feeding. Potent mosquitocidal effect coupled with its long half-life makes fluralaner an excellent candidate for drug based vector control strategies.

First report of the egg fertility of the hawksbill turtle (Eretmochelys imbricata) (Testudines: Cheloniidae) in Melaka, Malaysia

The unhatched eggs of the hawksbill turtle (Eretmochelys imbricata) are often found in the hatchery in Melaka, Malaysia, raising concerns if the eggs remain unfertilized. Examining unhatched eggs during post-emergence nest excavation could lead to eggs being mistakenly identified as unfertilized eggs due to the difficulty in differentiating between unfertilized eggs and early embryonic mortality. It is essential to determine the egg fertility of hawksbill turtles in Melaka before concluding that hatching failure is due to infertility. Egg fertility was determined using the white spot method conducted at the beginning of egg incubation on 50 clutches. Mean egg fertility was 85.9%, but the mean hatching success was significantly lower at 57.6% (mean emergence success was 56.8%). The results showed that egg fertility did not reflect hatching success and infertility was unlikely the cause of hatching failure. The huge number of undeveloped eggs may have been due to early embryonic death that went undetected at the end of incubation.

Factors regulating incubation temperature and thermal stress in hawksbills in St. Croix, USVI

The hawksbill sea turtle is listed as Critically Endangered under the IUCN Red List and has been slow to recover in the Caribbean due to historical exploitation and ongoing anthropogenic threats. In turtles, sex and reproductive success are determined by incubation temperatures, whereby lower temperatures produce male hatchlings and higher temperatures produce female hatchlings. As incubation temperatures increase due to climate change, nests are predicted to produce predominantly female hatchlings, threatening sex ratios, reproductive success, and species persistence. One of the largest remaining nesting hawksbill populations within the USA nests on Buck Island. This study aimed to (1) assess the factors driving incubation temperatures and (2) identify the relationship between hatch success and the proportion of time exposed to increasing incubation temperatures. Nest incubation temperatures, beach sector, habitat type, deposition month, percent soil composition, hatch success, and emergence success data were collected from 2019 to 2021. Differences in incubation temperatures across these factors confirmed that the absence of vegetative cover is increasing incubation temperatures on Buck Island, leading to reduced hatchling survival. Results from this study indicate that declines in hatch success may be driven by long-term exposure to temperatures that were previously considered in the literature to be non-lethal to embryos. These findings emphasize the continued need for conservation interventions to protect the future of hawksbills.

Home ranges and hatching success of threatened Eurasian curlew in north-eastern Europe relates to habitat type: Natural vs. agricultural landscapes

Farmland birds are among the most threatened species in Europe, largely as a result of the intensification of agriculture leading to widespread biodiversity losses. Ground-breeding shorebirds in grassland and arable habitats are particularly exposed to human threats and predation in highly modified landscapes; however, parts of their populations still breed in natural habitats and could provide a reservoir for threatened populations. This study aimed to improve our knowledge of the spatio-temporal use of breeding habitats by Eurasian curlew Numenius arquata arquata in a core area of the population in remote north-eastern Europe. A total of 83 adult birds across Europe were tagged with GPS devices between 2014 and 2022 to analyse their home-range sizes, habitat use and hatching success. Birds were distributed at breeding sites from 52°N to 66°N between Finland and the Ural Mountains. Forty-one percent of individuals nested in bogs, 33% in grassland, and 20% in abandoned farmland. Birds nested predominantly in bogs at northern latitudes and in grassland at southern latitudes, while abandoned farmland was mainly used at intermediate latitudes. The mean home range was largest for birds breeding predominantly in grassland while birds in bogs had the highest hatching success rate. Russia and Finland host the core population of the subspecies N. a. arquata during breeding period, which is essential for preserving the species on a European scale. Their survival may depend on well-preserved bogs and the maintenance of grassland areas, given that large areas of abandoned farmland are destined to become either forest or to be reclaimed for cereal crops or fodder grass in the short and medium terms. Given the large breeding populations in both countries, Russia and Finland have major responsibilities to maintain these essential populations on a biogeographical scale.

Brood protection is essential but not sufficient for population survival of lapwings Vanellus vanellus in central Switzerland

Lapwing are among those ground nesting bird species that suffered strong population declines following agricultural intensification in many parts of Europe. The key problem appears to be a low breeding success which, depending on the situation, may be due to predation of eggs and chicks, starvation of chicks especially during dry conditions, agricultural activities leading to direct killings, and suboptimal breeding habitat. Here, we report on a population of 40–60 lapwing breeding pairs in an intensively cultivated arable landscape in central Switzerland, where protection from farming activities, implementation of special lapwing habitat and nest fencing to exclude terrestrial predators (mainly red fox) started in 2005 and is still ongoing. Chicks were ringed and families subsequently observed every 2–3 days. Hatching success for fenced nests built before May was high. Low hatching success was observed in unfenced nests due to high predation rates and in late nests due to abandonment by the female when the vegetation was growing too tall (e.g. maize). Regularly, chicks disappeared during the night shortly after hatching. Most likely many of them first left the fence and were predated outside. Our observations from a fenced field with wet soils and puddles suggest that lapwing may produce sufficient offspring if predation can be reduced and if large enough areas with suitable habitat are available.

Exploration behavior differs between Darwin’s finch species and predicts territory defense and hatching success

Darwin’s finch species in the Galápagos Islands are famously distinguished by their morphology but less attention has been given to behavioral differences between species. In this study, we compared behavior between four Darwin’s finch species on Floreana Island: small ground finch (Geospiza fuliginosa), medium ground finch (G. fortis), small tree finch (Camarhynchus parvulus), and medium tree finch (C. pauper). After capturing birds using mist-nets, we measured three behavioral traits: (1) boldness during human handling, (2) exploration in a novel environment, and (3) aggressiveness towards their mirror image. First, we found that ground finches were bolder and more exploratory than tree finches, consistent with their distinct ecological niches on Floreana Island and with the theoretical prediction that diet generalists should be less wary of novelty. Second, we tested the ecological validity of these behavioral variables at the individual level by relating them to territory defense behavior and breeding success. We found that males that were more exploratory in the novel environment also reacted more aggressively to a simulated territory intruder and showed lower offspring hatching success during the breeding season. Hence, our findings support previous work showing behavioral differences between Darwin’s finch species and also suggest pathways by which behavioral differences among individuals might influence fitness.Significance statementClosely-related species that overlap in their geographical range may differ in their morphology and/or behavior, allowing them to occupy different ecological niches. In this study, we explored behavioral differences between four Darwin’s finch species on Floreana Island in the Galápagos Archipelago. We found clear interspecies differences in behavior, with the ground finches struggling more often during handling (boldness) and visiting more sectors in a novel environment (exploration) compared to the tree finches. After birds were released, we continued to observe a subset of male finches in the wild. An individual’s exploration behavior significantly predicted both its aggressive response to a territory intruder (simulated using song playback) and offspring hatching success during the breeding season. This suggests that individual differences in exploration behavior can potentially be used as a proxy for territorial behavior in the wild and may also predict fitness outcomes.

Nesting trends and predation risks among yellow-spotted river turtles in Essequibo River Basin

The yellow-spotted river turtle (Podocnemis unifilis), inhabiting Amazon, Orinoco, and Essequibo River basins, is classified as vulnerable due to historical exploitation and current threats. Efforts have been made throughout the Amazon basin to understand the ecology of yellow-spotted river turtles and implement conservation measures, but the Essequibo River basin located in Guyana, remains the least studied part of the geographical range of the species. In this study we present data collected over a three-year period from 2020 to 2023, as part of a community driven conservation program by Yupukari village, in the North Rupununi, Guyana. We describe the nesting behavior of P. unifilis,and assess predation of eggs in the wild. A total number of nests in 9 beaches ranging from 59 (in 2021) to 76 (in 2023) (in averge 6.68 nest/beach, and 14.2 nests per ha) with an average number of 20.45 eggs per nest. Nesting locations were found to be predominantly situated within 1–20 m from the river, in proximity to vegetation, and on fine sand, with temperatures consistently falling within the 27–29 degrees Celsius range. Importantly, this study unravels the critical issue of nest predation, with lizards, human, and the birds emerging as the primary culprits, impacting nests located closer to vegetation to a greater extent. All nests in sites which potentially would be flooded were moved for a hatchery in the community of Yupukari in which the hatching success reached 83%.

Ingestion of paralytic shellfish toxins in a carnivorous gastropod (Chorus giganteus): effects on their elemental composition and reproductive traits

The producer of paralytic shellfish toxin (PST), Alexandrium catenella, is one of the main generators of HABs in the coasts of Chile. Its presence produces ecological and economic damage, directly affecting filter-feeding organisms, and indirectly to other organism through the trophic chain. The objective of this research was to identify the effect of a toxic diet on the energetic and reproductive parameters of the carnivorous snail Chorus giganteus. Two groups of snails were used, one fed with toxic prey (bivalves fed with A. catenella), and the other fed with non-toxic prey. Both treatments were maintained under these conditions for 63 days, then, elemental composition (C, N) and energy content were estimated, and fecundity parameters were analyzed. The results indicate that snails fed with toxic prey had a lower percentage of C and C/N ratio. The energy content was significantly lower in intoxicated snails. Regarding fecundity parameters, a higher number of egg-masses were produced by toxic snails, however, only 62% of these showed embryonic development, with 57% hatching success. A negative relationship was identified between the mean PST concentration, quantified in snails, and the number of egg-masses produced per aquarium. In the aquarium where the snails had highest average PST concentration (1200 ± 820 μg STX.2HCL eq. Kg−1) there was no oviposition, while egg-masses were only produced by snails in aquaria where the average concentration did not exceed 360 ± 160 μg STX.2HCL eq. Kg−1. It is likely that, with low levels of accumulated PST, C. giganteus activates its oviposition process as a response to toxin-induced stress, generating a higher energy expenditure supported by a redirection of its reserves. However, when the intoxication presents higher levels, the reproductive process could be inhibited, similar to what has been identified in other molluscs.

Hatching success and growth of Snakehead (Channa lucius Cuvier, 1831) larvae and fry at different pH levels

Snakehead (Channa lucius Cuvier, 1831) is a species of potential aquaculture interest in the Mekong Delta, Vietnam. However, their optimum environmental conditions have yet to be determined. This study aims to study the hatching success and larval and fry growth of C. lucius at six pH levels (5.5, 6.0, 6.5, 7.0, 7.5, and 8.0). Two consecutive experiments were conducted. Experiment 1 focused on incubating eggs and nursing the yolk sac larvae, and was carried out in aquariums. The monitoring included incubation time (IT), hatching rate (HR), and deformation rate of the newly hatched larvae (DR). Larvae were also collected daily during nursing for growth determination. In Experiment 2, four-day-old fry after hatching from experiment 1 were reared in plastic tanks with live feeds for 30 days. Growth was checked every ten days, while survival rate (SR) and coefficient of variation (CV) were determined at the end of the experiment. pH 5.5–8.0 was favorable for incubation, larvae, and fry, as assessed through good indicators of IT, HR, DR, and larval length and weight growths, as well as length and weight growths, SR, and CV of fry. Furthermore, the lowest DR (0.33%) was at pH 5.5, while except for pH 7.0, the shortest IT (41.1 h) significantly differed from that at higher pH levels (p < 0.05), and the highest larval growth parameters were at pH 5.5–6.0; meanwhile, pH 5.5–6.5 supported a better life for fry, as showed by the significantly higher growth parameters (p < 0.05) and SR and CV improvements in fry after 30 rearing days. Overall, pH 5.5–8.0 was suitable for the early stages of C. lucius, in which pH 5.5–6.0 was better for incubation and larval growth and pH 5.5–6.5 was better for fry development.

Preliminary data on the diet composition and nesting behaviour of the Long‑legged Buzzard (Buteo rufinus) in south‑western Romania

The study of a nest of Long‑legged Buzzard Buteo rufinus was carried out using a trail camera and is one piece of a completely unknown jigsaw puzzle of diet and nesting behaviour in Romania. With a hatching success of 75%, we identified 3 hatched chicks from the 4 eggs. During the 10 days of monitoring, 34 preys brought to the nest were identified, with a peak of activity between 11:00–17:00 and a preference for the European Ground Squirrel Spermophilus citellus (61.76%). This was followed by the Domestic Pigeon Columba livia f. domestica and the Common Wood Pigeon C. palumbus (5.88%), and amphibians were represented by the European Green Toad Bufotes viridis (2.94%). There were 10 unidentified prey species (29.41%). We identified the presence of plastic and textile fibres in the nest and the risk of chick suffocation. We also improved our understanding of interspecific interactions and our observations highlighted the mutualism between the three species in the nest: Spanish Sparrow, House Sparrow and LLB. The removal of solitary trees from the agricultural landscape is a major threat in south‑western Romania, affecting the breeding population of the LLB, which, as in our case, nests on this type of support.

Carbon Nanotubes (CNTS) and Frankincense Nanoparticles as Promising Insecticides to Control Onion Thrips

Thrips tabaci Lindeman (Thysanoptera: Thripidae) is one of the most common and devastating onion pests which is capable of causing substantial harm to onion crops. Synthetic pesticides are mainly used to control onion thrips. T. tabaci requires alternative, low-impact control measures since there are numerous difficulties with utilizing chemical pesticides, including pesticide resistance. This study aimed to evaluate the effectiveness of the nanomaterial compounds on adults and nymphs of the T. tabaci in vivo and study their physiological changes caused by pesticides. The findings demonstrate that using nanomaterials, such as carbon nanotubes (CNTs) and frankincense nanoparticles (FNPs), significantly impacts the number of onion thrips. It also has the potential to lower the risk of pesticide resistance. According to the preliminary results, using carbon nanotubes (CNTs) considerably increased the mortality rate of adults and nymphs of T. tabaci and decreased egg-hatching success. Carbon nanotube (CNTs) and frankincense nanoparticles showed a high death rate in adult and nymphal stages at a concentration of 0.05 percent. Carbon nanotubes (CNTs) demonstrated exceptional mortality rates in adult and nymphal stages, with 90 and 50 percent at 5 mg/mL concentrations. Frankincense nanoparticles (FNPs) treatment demonstrated a high adult mortality rate of around 60 percent compared to the control treatment. Eggs of onion thrips showed different hatching success rates after treatment with CNTs and FNPs. The egg hatch rate did not exceed 40 percent of hatched eggs in the CNTs treatment compared to 90 percent in the control treatment. On the other hand, number of laid eggs per female did not differ significantly, indicating that none of the treatments affected the fecundity of the females. The ability of thrips to develop resistance to CNTs and frankincense compounds requires additional investigation. These natural products could be a suitable alternative to control destructive pests like onion thrips.

Influence of broodstock nutrition on egg quality and fatty acid composition in California Yellowtail

AbstractObjectiveCalifornia Yellowtail (CYT) Seriola dorsalis are continuous spawners and rely entirely on their diet to supply nutrients like fatty acids (FAs) to their eggs to support early development. The objective of this study was to determine whether commercial diets could replace a diet consisting of fresh fishery products (FFP‐D) without compromising egg quality and biochemical composition, specifically FAs.MethodsIn 2017, one broodstock group (one female and two males) was fed a formulated reference feed (REF‐D; Bio‐Oregon). This pilot experiment showed that it was possible for a minimum of one female and two male broodfish to spawn repeatedly in a tank, a finding that led to a replicated diet experiment during 2018 in which 18 CYT broodfish were divided into six replicate tanks, with one female and two males per tank. Three tanks were fed the FFP‐D as a control, and three tanks were fed a commercial diet (COM‐D; Breed‐M, INVE). For each spawning event, egg quality metrics were collected, along with samples for FA analysis.ResultThe 2017 REF‐D treatment produced eggs that met arachidonic acid (ARA) and eicosapentaenoic acid (EPA) requirements and had egg metrics comparable to those obtained from the FFP‐D, with higher viability and average batch fecundity. However, the REF‐D treatment had insufficient docosahexaenoic acid (DHA) and no tank replicates. The 2018 COM‐D treatment produced eggs with large egg and oil diameters and met ARA and EPA requirements but was associated with very poor spawning and hatch success and had insufficient DHA levels. The FFP‐D treatment produced below‐average viability and batch fecundity rates and was unable to meet most essential FA requirements, but it yielded the greatest number of spawning events.ConclusionNone of the experimental treatments, including the control, was able to fully meet the nutritional requirements of CYT broodstock. These results reveal crucial data about current CYT broodstock diets that can facilitate future research for developing nutritionally complete diets, especially in terms of essential FAs.

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.

Hatching Failure and Success of Hawksbill Sea Turtles (Eretmochelys imbricata) in Semi-Natural Nests Karimunjawa.

Hatching success and failure is influences by the interaction between biotic and abiotic factors during the incubation period. Non optimal nest is susceptible to bacterial contaminated eggs during incubation period and hatchling morphology. The purpose of the study is to understand the relationship between environmental conditions of semi natural nest with bacteria contaminant, hatchlings allometry and abnormality. The method used was quantitative descriptive which are nest temperature and humidity measurement, hatchlings allometry measurement, bacteria observation of gram negative with EMB (Eosin Methylene Blue) agar, TPC (Total Plate Count), bacteria characteristic morphology and hatchlings abnormality observation. The result showed that semi natural nest have high temperature (30˚C) and high humidity (70%) caused smaller hatchlings and negative allometry growth, hatchlings abnormality and bacterial contaminant. TPC showed that the number of bacteria unhatched eggs (1,42 x ) more than hatched eggs (1,03 x ). The bacteria colonies were suspected to be from Enterobacteriaceae family according to microscopic and macroscopic morphological characteristic. Macroscopically, the bacteria morphology is dominated by a round shape, concentric surface, flat edges, flat elevation and pink color, meanwhile microscopic form is bacilli. There is significant correlation between environmental conditions of semi natural nest with hatchlings growth, hatchlings abnormality and eggshells bacteria

ASSESSMENT OF A COMMUNITY MANAGEMENT PROGRAM OF RIVER TURTLES (PODOCNEMIDIDAE: Podocnemis) IN ZÁBALO, ECUADORIAN AMAZON

In Zábalo community within the Cuyabeno Fauna Production Reserve, a 26-year local initiative aimed at river turtle management was initiated following a significant decline in Podocnemis unifilis and P. expansa populations. Despite the program's lengthy history, weak monitoring and validation procedures prompted a comprehensive evaluation of management efficacy to strengthen the communitarian program. This assessment encompasses population estimates derived from nesting data (density, abundance, hatching success, hatchling production) for P. unifilis between 1994 and 2019. Some available data were also compiled for P. expansa which has not been the main focus of the communitarian program. Results highlight a positive temporal trend in P. unifilis population estimators, and a consistent high hatching success (81%), underscoring the program's contribution to the conservation of the species. Nonetheless, further research is imperative to assess age-specific population trends and enhance monitoring and management strategies for the relatively rare P. expansa.

Artificial Spawning Techniques for Catfish (Clarias gariepinus) at the Cultivated Fisheries Production Business Service Center, Karawang, Indonesia

One of the primary challenges in the catfish cultivation industry is the uncertainty (mostly due to weather conditions, natural feed availability, pests and diseases), limited availability, and often poor quality of catfish frys. Fry quality is crucial in aquaculture, yet its reliability is hampered by the natural spawning process, which is influenced by seasonal variations. To address this issue, artificial spawning techniques offer a viable solution. This activity aims to comprehend and effectively execute the precise methods of artificial spawning for catfish, ultimately striving for the production of high-quality fingerlings. Data collection involved the acquirement of both primary and secondary data. The artificial spawning process encompasses container and medium preparation, meticulous broodstock selection and breeding, the artificial spawning procedure, larval rearing, and nursery management. Results from the artificial spawning efforts revealed a fecundity of 75,000 individuals, a remarkable 90% fertilization rate, an 89% hatching success, and an impressive 90% survival rate. Notably, catfish fingerlings were found to harbor parasites such as Gyrodactylus sp., Trichodina sp., and Dactylogyrus sp. This occurrence can be attributed to the high population density of fish, which contributes to a decline in water quality, emphasizing the importance of cautious management practices in aquaculture.

Evidence for infection influencing survival of the freshwater copepod Salmincola californiensis, a parasite of Pacific salmon and trout.

We explore apparent infection of Salmincola californiensis arising during investigations involving this lernaeopodid copepod parasitic on Pacific salmon and trout Oncorhynchus spp. We noted occasional unusual coloration of adult female copepods collected from the wild. These females were bright blue and pink in contrast to the cream white coloration characteristic of the copepod. We also observed that similar color patterns developed under laboratory settings when copepod eggs were held for hatching. In paired egg cases, we found consistent hatching failure of blue and pink eggs and patterns in apparent disease development that would be consistent with both vertical and horizontal transmission. Attempts to identify the cause of the apparent infection using genetic methods and transmission electron microscopy were inconclusive. Iridovirus infection was initially suspected, but bacterial infection is also plausible. This apparent reduced hatching success of S. californiensis warrants further exploration as it could reduce local abundances. Given the potential importance of a disease impacting this copepod, a parasite that itself affects endangered and commercially important Pacific salmon and trout, future research would benefit from clarification of the apparent infection through additional sequencing, primer development, visualization, and exploration into specificity and transmission.

Efficacy of artificial nest shading as a climate change adaptation measure for marine turtles at Ascension Island

AbstractSuccessful embryonic development and offspring sex ratios of marine turtles are determined by thermal conditions experienced during incubation, rendering them potentially vulnerable to anthropogenic climate change. With the rate of projected temperature rises likely to outpace the adaptive capacity of long‐lived species such as marine turtles, there is growing interest in management interventions aimed at mitigating the effects of climate change at nesting grounds. In this study, we experimentally tested the impacts of artificial nest shading on the incubation temperature, hatching success, and predicted offspring sex ratio of green turtle (Chelonia mydas) clutches at Ascension Island. Clutches (n = 97) were sampled from 2 nesting beaches with naturally contrasting thermal environments (one hot; one cool) and either left as in situ controls or relocated to shaded or unshaded hatcheries on their beach of origin. Compared to unshaded experimental clutches, shading reduced mean incubation temperatures and sex‐determining temperatures (i.e., middle third of embryonic development) by 0.5–0.9°C and 0.5–1.2°C respectively, with the reduction being greater on the hotter beach. Shading also differentially affected hatchling output across the 2 sites: on the hot beach, shading significantly improved hatching success by ~23% but had minimal effects on offspring sex ratio; whereas on the cooler beach, shading did not impact hatching success but resulted in ~12% more male offspring. Interestingly, mean incubation temperatures of in situ controls did not differ significantly from shaded clutches, and were significantly cooler than unshaded experimental clutches, suggesting relocation may have negated some of the benefits of shading. Our results demonstrated that artificial shading may be a viable approach for partially offsetting climate change impacts on nesting marine turtles; however, scalability will be a major challenge in achieving conservation objectives at high‐density nesting sites like Ascension Island.

Effects of mine tailing exposure on the development of early life stages of the marine copepod Calanus finmarchicus

ABSTRACT The demand for mineral resources is increasing mining activities worldwide. In Norway, marine tailing disposal (MTD) is practiced, introducing mineral particles into fjord ecosystems. We investigated the effects of two concentrations (high and low) of fine tailings from a CaCO3 processing plant on early life stages of the marine copepod Calanus finmarchicus. Results show that the exposure did not significantly impact hatching success or development in non- and early feeding life stages. However, feeding stage nauplii ingested tailings, which caused a significantly slower development in later nauplii stages in high exposure groups, with most individuals being two stages behind the control group. Further, high mortality occurred in late nauplii and early copepodite stages in low exposure groups, which could be caused by insufficient energy accumulation and depleted energy reserves during development. Individuals exposed to high exposure concentrations seemed to survive by arresting development and potentially by reduced activity, thereby conserving energy reserves. In nature, slower development could affect lipid storage buildup and reproduction.