Egg Clutches Research Articles

The smallest known complete dinosaur fossil eggs from the Upper Cretaceous of South China

ABSTRACT The Upper Cretaceous Ganzhou Basin of Jiangxi Province, South China is among one of the richest egg fossil sites in the world and yields abundant exquisite egg clutches and embryonic eggs, especially in oviraptorosaurs. Hadrosaurian, troodontid, and potential dromaeosaurid egg fossils were also reported, though they were rare. All these reported eggs vary in morphology but have relatively large sizes. Here, we report a partial egg clutch with six complete small eggs from the Upper Cretaceous Tangbian Formation of Ganzhou City, Southeast China. The microstructure of the eggshell indicates that it can be assigned to Ovaloolithidae. Hence, we established a new ootaxon, Minioolithus ganzhouensis oogen. et oosp. nov. based on a unique combination of characters, including a small egg size, irregular egg arrangement, worm-like and nodular ornamentation, and a gradual boundary between two structural layers. The egg morphology and eggshell microstructure support it to be the smallest known non-avian theropod egg up to date. This discovery increases the diversity of dinosaur eggs in the Late Cretaceous and is significant for our understanding of the evolution of theropods in the Late Cretaceous.

Parental care of underwater egg clutches in Andean water frogs (Anura: Telmatobiidae)

The most generalized reproductive mode in anurans is the deposition of egg clutches in water that develop into exotrophic aquatic tadpoles. Yet, despite this extended distribution, cases of parental care on submerged egg clutches are poorly documented. Because of its high diversity, its aquatic habits, and reports on males of two species standing next to the clutch, the Andean genus Telmatobius Wiegmann, 1834 offers an excellent model to examine the evolution of such behavior and the factors influencing it. Here, we combine field and laboratory studies to describe the breeding biology and parental care behavior on Telmatobius culeus (Garman, 1876), Telmatobius hintoni Parker, 1940, Telmatobius intermedius Vellard, 1951, Telmatobius jelskii (Peters, 1873), and Telmatobius oxycephalus Vellard, 1946. Our findings indicate that these five species have prolonged breeding season, and use concealed underwater shelters between rocks or macrophytes for mating and egg deposition. We showed that clutches of 35–560 eggs are deposited in these shelters. Males were observed next to the egg clutch and defending it aggressively against intruders, including conspecifics. Females were, on average, larger than males supporting the hypothesis that competition among males does not drive sexual size dimorphism in the genus. Our findings provide meaningful data to use in conservation programs, given that most species of Telmatobius are considered endangered and fill a significant information gap in understanding parental care’s origin in Nobleobatrachia.

Fate and effects of an environmentally relevant mixture of microplastics in simple freshwater microcosms

Most studies assessing the effects of microplastics (MPs) on freshwater ecosystems use reference materials of a certain size, shape, and polymer type. However, in the environment, aquatic organisms are exposed to a mixture of different polymers with different sizes and shapes, resulting in different bioaccessible fractions and effects. This study assesses the fate and effects of an environmentally relevant mixture of high-density polyethylene (HDPE) fragments, polypropylene (PP) fragments, and polyester (PES) fibres in indoor freshwater microcosms over 28 days. The MP mixture contained common polymers found in freshwater ecosystems, had a size range between 50 and 3887 µm, and was artificially aged using a mercury lamp. The invertebrate species included in the microcosms, Lymnea stagnalis (snail) and Lumbriculus variegatus (worm), were exposed to four MP concentrations: 0.01, 0.05, 0.1 and 1 % of sediment dry weight. MPs fate was assessed by performing a balance of the MPs in the surface water, water column, and sediment after a stabilization period and at the end of the experiment. Sedimentation rates per day were calculated (2.13 % for PES, 1.46 % for HDPE, 1.87 % for PP). The maximum size of MPs taken up by the two species was determined and compared to the added mixture and their mouth size. The size range taken up by L. variegatus was smaller than L. stagnalis and significantly different from the size range in the added mixture. The No Observed Effect Concentrations (NOECs) for the reproduction factor of L. variegatus and the number of egg clutches produced by L. stagnalis were 0.01 % and 0.1 % sediment dry weight, respectively. The EC10 and EC50 for the same endpoint for L. stagnalis were 0.25 % and 0.52 %, respectively. This study shows that current MP exposure levels in freshwater sediments can result in sub-lethal effects on aquatic organisms, highlighting the importance of testing MP mixtures.

Long-term effects of an early-life exposure of fathead minnows to sediments containing bitumen. Part II: Behaviour, reproduction, and gonad histopathology

The oil sands area of northern Alberta has river sediments that contain natural bitumen. Eggs and fish in these rivers may be exposed to bitumen-related chemicals early in life. This paper assesses a short embryo-larval fish exposure to oil sands sediment and follows the fish behaviour as they mature in clean water and examines their breeding success as adults (5 months afterwards). The three different oil sands river sediments tested were: a sediment collected outside of the bitumen deposit (tested at 3 g/L, Reference sediment from upstream Steepbank River site), and two sediments collected within the deposit (each tested at low (1 g/L) and high (3 g/L) concentrations). The sediments within the bitumen deposit were from the Ells and Steepbank (Stp) Rivers, and both contained significant total PAHs (>170 ng/g wet weight sediment) and alkylated PAHs (>4480 ng/g). Fish were exposed to these sediments for 21 days (as eggs and larval fish), and then transferred permanently to clean water to mature and breed. There was a significant decrease in the number of egg clutches produced by fish exposed early in life to Stp downstream high sediment (compared to Reference sediment). There was also a decrease in overall cumulative egg production, with fish from Stp downstream high sediment producing just over 1000 eggs in total while fish exposed to Ref sediment produced nearly 6900 eggs. The fish with reduced egg production were also less social than expected as they matured, and they had a lower % of early vitellogenic eggs in their ovaries. Overall, the exposure shows that a single, brief exposure during early life stages to natural bitumen can affect fish in adulthood. Naturally occurring bitumen-derived PAHs can reduce fish reproductive output by complex mechanisms, measurable as lower ovary maturity and changes in social behaviour.

High thermal tolerance of egg clutches and potential adaptive capacity in green turtles

Climate warming threatens sea turtles, among other effects, because high temperatures increase embryo mortality. However, not all species and populations are expected to respond the same way because they could have different thermal tolerances and capacities to adapt. We tested the effect of incubation temperature on egg mortality in a population of green turtles (Chelonia mydas) previously suggested to be less affected by extreme climatic events than others. We (1) assessed the relationship between temperature and hatching success, (2) defined an optimal range of temperatures that maximized hatching success and (3) assessed the variability in the response to temperature among clutches laid by different mothers, which could allow adaptation. Hatching success was consistently high in green turtle clutches with a skew toward high values, with 50 % of clutches having a success above 94 %. Yet, it was mildly affected by temperature, declining at both low and high temperatures. The optimal range of mean incubation temperatures was between ~30.5 °C and 32.5 °C. Current mean temperatures (31.3 °C) fall within the middle of the optimal range, indicating a potential resilience to further rises in mean nest temperature. Hatching success was best described by nest temperature and the interaction between female identity and temperature. This last predictor indicated a variability in thermal tolerance among clutches laid by different mothers and therefore, a capacity to adapt. The studied population of green turtles seems to be less vulnerable than others to climate warming. Understanding how different populations could respond to increasing temperatures could help complete the picture on the potential effects of climate change on sea turtles.

Land-based foraging by polar bears reveals sexual conflict outside mating season

According to sexual selection theory, the sexes are faced with opposing evolutionary goals. Male fitness benefits from access to females, whereas female fitness is constrained by food resources and safety for themselves and their offspring. Particularly in large solitary carnivores, such as polar bears (Ursus maritimus), these divergent goals can potentially lead to conflict between the sexes. Outside the mating season, when polar bears are on the move across vast distances, the consequences of such conflict can become apparent when individuals arrive at the same food source. To investigate interrelationships between the sexes, we observed successive polar bears visiting a bird breeding colony to feed on clutches of eggs. We found that males succeeded females more frequently and more closely than expected by chance. Moreover, when males were closer to conspecifics, they walked faster, spent less time in the colony and ingested less food. In contrast, female foraging performance was not associated with proximity to other bears. Irrespective of proximity, females generally spent short periods in the colony and ingested fewer clutches than males. Our results suggest that in polar bears, there is a trade-off between the benefits of food intake and the opportunities (in males) and risks (in females) posed by encountering conspecifics.

Effects of maternal androgens and their metabolite etiocholanolone on prenatal development in birds.

Offspring phenotypes can be affected by maternal testosterone and androstenedione (A4), which are considered a tool of mothers to adjust offspring to a fluctuating environment. Yet testosterone and A4 are very rapidly metabolized by developing avian embryos, suggesting that either the maternal testosterone and A4 have potent organizational effects on the embryos extremely early before being metabolized or it is the metabolites that evoke phenotypic variation in the offspring. One of the metabolites, etiocholanolone, increases substantially during early embryonic development and is a likely candidate for mediating maternal effects as it can promote erythropoiesis. To investigate and compare the effects of testosterone and A4 with the possible effects of etiocholanolone during prenatal embryonic development, we increased their levels in black-headed gull eggs (Larus ridibundus), and used sham-injected eggs as controls. This species usually has 3-egg clutches in which maternal androgen levels increase with the egg-laying sequence. We analysed embryonic heart rate, peri-hatching biometric traits, the ratio of white to red blood cells (W/R ratio) and bursa development. We found that testosterone and A4 treatment increased embryonic heart rate irrespective of egg-laying sequence and decreased bill length and W/R ratio, whereas etiocholanolone did not mimic these effects. Instead, etiocholanolone treatment decreased tarsus length and brain mass. Our finding that etiocholanolone does not mimic the effects induced by testosterone and A4 suggests that the embryonic metabolism of maternal testosterone and A4 can potentially diversify the function of these maternal androgens.

Inclusion of Linseed (Linum usitatissimum) Meal on the Performance of Vanaraja Birds

The present study was carried out with the objective of studying the reproductive performance, blood constituents and economics of rearing Vanaraja birds as influenced by the dietary inclusion of linseed meal. The study was conducted at the poultry unit of the department. A total of 120 female Vanaraja chicks were reared for a period of nine months and were randomly divided into four treatment groups (T1, T2, T3, and T4) of 30 birds, each having five replications per treatment following a randomized block design. They were subjected to four dietary levels of linseed meal, containing 0%, 4%, 8%, and 12%, respectively. The birds were reared under a deep litter system up to 8 weeks of age and thereafter in cages following standard management practices. Initial body weight was recorded at 1 day old, and thereafter it was recorded fortnightly. Feed intake and egg production were recorded daily. The control group had higher egg production, clutch size, and egg weight. Higher yolk weight, albumen weight, and yolk cholesterol were recorded in T3, while group T4 had the maximum HU. The lowest cholesterol and triglycerides were recorded in T4, while the highest HDL and lowest LDL were observed in the control group. The cost of production was highest in T4 and lowest in T2, while higher net profit per bird and net profit per gain were recorded in T3 as compared to the control group.

The female red jungle fowl (Gallus gallus gallus) reproductive investment stimulated by male attractiveness

Abstract. Lelono A, Riedstra B, Groothuis T. 2024. The female red jungle fowl (Gallus gallus gallus) reproductive investment stimulated by male attractiveness. Biodiversitas 25: 2931-2936. To maximize their capacity for reproduction, mothers are expected to modify their investment in offspring based on the quality of their mates. A recent study showed that females in female-care only species do so by investing more in egg mass when mated with attractive males rather than in other reproductive traits. In our study, we investigated how red jungle fowl (Gallus gallus gallus) mothers invest in clutch production based on the size of the male's comb, a trait signaling attractiveness. We randomly paired 14 females with 14 males of either large or small combs and monitored their egg laying, clutch completion, and brood rearing. Following the initial clutch, we exchanged male partners and permitted females to establish up second generation. We found that females who were partnered with males who had bigger combs laid down their eggs earlier after pairing compared to those paired with males with smaller combs. However, there were no variations in egg mass or clutch size that we could find. Furthermore, the size of the male's comb influenced the growth and body condition of female chicks, with those sired by males with larger combs being heavier and in better condition at twenty-four weeks old. These data support the premise of the positive Differential Allocation (DA) hypothesis, where maternal investment varies with mate quality, rather than the negative DA, where females more investment in offspring from lower quality mates.

Aspects of the demography of two Podarcis muralis populations in anthropogenic modified habitats in western France, based on a non-invasive sampling method

Urbanisation impacts on both abiotic and biotic characteristics of the environment and is likely to bring new selective pressures on animal species living within these areas. The common European wall lizard Podarcis muralis adapts well to urbanisation and indeed may be described as the archetypical urban lizard. In this paper we investigated some aspects of the demography of two populations of P. muralis from western France, one living in a hedgerow system situated in an agricultural area on the edge of a village and a second in an urban garden. The active year in both populations was from February–March until October–December, the latter in the urban garden where temperatures were higher. Numbers decreased from around June then increased again during September but this varied annually and between populations. Diversity and equality indexes for both populations were high, especially in females, indicating a range of individuals and their frequency of presence. Both populations were therefore stable despite only limited numbers of lizards being present for more than one year. Male lizards with high presence were more frequently seen in the company of females than males that were seen less frequently. Hatchling lizards were seen from June after the spring mating period with a second period of hatchlings appearing during autumn. This supports the notion that females annually deposit two clutches of eggs in the area. Keywords: lizards, Podarcis muralis, demography, western France, non-invasive sampling

Effects of temperature and resource level on interspecific interactions in two species of Odonata larvae.

Identifying how temperature and food resources affect interactions between species is important for understanding how climate change will shape community structure in the future. Here, we tested how temperature and resource density affect survival and growth in the larval stage of two coexisting odonates: the damselfly Lestes sponsa and the dragonfly Sympetrum vulgatum. We performed a laboratory experiment at two temperatures (21 and 24°C) with two resource densities. We estimated the timing of egg hatching of individual egg clutches and thereafter the larval growth rate-, survival- and size-mediated priority effects under interspecific conditions. Eggs of both species hatched slightly faster at 24°C, and S. vulgatum eggs started hatching approximately 1 day earlier than L. sponsa eggs. However, this earlier hatching did not result in a size-mediated priority effect, that is, a higher predation on the later hatching L. sponsa. Nevertheless, L. sponsa larvae were significantly larger than S. vulgatum at hatching. Growth rate and survival were significantly higher: (1) at 24°C compared with 21°C, (2) at high compared with low-resource density and (3) in L. sponsa compared with S. vulgatum. Several significant interaction effects between resource density and temperature and between temperature and species were found. At high temperature, L. sponsa had a higher growth rate than S. vulgatum, but no difference in growth rate between species was found at low temperature. Additionally, a high-resource density resulted in a higher growth rate in both species, but only under high temperature. There was a negative relationship between growth rate and survival in both species, suggesting that the higher growth rate of larvae was to some degree driven by intraguild predation and/or cannibalism. Our results imply that resource levels interact with temperature to affect interactions between the species.

Xinyang flavivirus, from Haemaphysalis flava ticks in Henan Province, China, defines a basal, likely tick-only Orthoflavivirus clade.

Tick-borne orthoflaviviruses (TBFs) are classified into three conventional groups based on genetics and ecology: mammalian, seabird and probable-TBF group. Recently, a fourth basal group has been identified in Rhipicephalus ticks from Africa: Mpulungu flavivirus (MPFV) in Zambia and Ngoye virus (NGOV) in Senegal. Despite attempts, isolating these viruses in vertebrate and invertebrate cell lines or intracerebral injection of newborn mice with virus-containing homogenates has remained unsuccessful. In this study, we report the discovery of Xinyang flavivirus (XiFV) in Haemaphysalis flava ticks from Xìnyáng, Henan Province, China. Phylogenetic analysis shows that XiFV was most closely related to MPFV and NGOV, marking the first identification of this tick orthoflavivirus group in Asia. We developed a reverse transcriptase quantitative PCR assay to screen wild-collected ticks and egg clutches, with absolute infection rates of 20.75 % in adult females and 15.19 % in egg clutches, suggesting that XiFV could be potentially spread through transovarial transmission. To examine potential host range, dinucleotide composition analyses revealed that XiFV, MPFV and NGOV share a closer composition to classical insect-specific orthoflaviviruses than to vertebrate-infecting TBFs, suggesting that XiFV could be a tick-only orthoflavivirus. Additionally, both XiFV and MPFV lack a furin cleavage site in the prM protein, unlike other TBFs, suggesting these viruses might exist towards a biased immature particle state. To examine this, chimeric Binjari virus with XIFV-prME (bXiFV) was generated, purified and analysed by SDS-PAGE and negative-stain transmission electron microscopy, suggesting prototypical orthoflavivirus size (~50 nm) and bias towards uncleaved prM. In silico structural analyses of the 3'-untranslated regions show that XiFV forms up to five pseudo-knot-containing stem-loops and a prototypical orthoflavivirus dumbbell element, suggesting the potential for multiple exoribonuclease-resistant RNA structures.

Long-term monitoring of dwarf eggs in clutches of Yellow-legged Gulls (Larus michahellis) breeding in a western Mediterranean colony

The present study provides data on clutches with dwarf eggs from a large sampling in a colony of Yellow-legged Gulls (Larus michahellis) over 31 years. Their occurrence was very low, with a global percentage of 0.26%. Significant variations were not detected among periods of 10 or 11 years. In all the cases, only one dwarf egg was found per clutch. Mean volume of dwarf eggs was 34% of that of non-dwarf eggs. Their content was mostly albumen and a very reduced quantity of yolk, and they were infertile. Several results of the study (the laying order of the dwarf eggs, their mean clutch size and the mean size of the non-dwarf eggs from clutches with dwarf eggs) support the hypotheses that runt eggs occur from a temporary disturbance to the reproductive tract.

Wild black soldier flies, Hermetia illucens (Diptera: Stratiomyidae): Seasonal availability and life history traits in two common organic streams in Bangladesh

The black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomyidae) is a “crown jewel” in waste management because it rapidly bioconverts organic streams into nutrient-rich biomass. Bangladesh's inefficient waste management has caused serious environmental issues due to the massive amounts of organic waste, mainly livestock manures and municipal organic waste, generated daily. We need reliable BSF to maximize our organic resources. To establish a long-term, stable BSF colony, we closely examined the seasonal abundance and life cycle features of BSF raised on municipal garbage and poultry manure in a regional natural environment in the lab. This investigation lasted two years (2019–2020). Season and raising substrates affected wild BSF egg clutches and life cycles. Organic waste dumps captured the most egg clutches in rainy seasons and the fewest in cooler months. Municipal rubbish dumps consistently produced wilder BSF egg clutches than poultry manure dumpsites. The BSF larvae grew slower in winter and faster in the rainy season, independent of substrate. Winter was optimal for adult BSF longevity in all organic streams. Winter cultivated wild BSF on two organic streams exhibited fewer egg clutches per female, shorter and lighter prepupae, and lower adult ecolosion rates than wetter months. While BSF given municipal organic wastes had the highest adult ecolosion rates, BSF fed poultry manure had more variation in prepupae length and weight, adult lifespan, and egg clutches. Larval development was faster with poultry manure BSF than with municipal organic waste. The protein and ash content of prepupae rearing on poultry manure exceeded those of prepupae on urban organic waste, although fat content was equivalent. These findings indicate that both types of organic streams may be suitable substrates for BSF larvae for trash treatment.

Population ecology of the intertidal xanthid crab Leptodius exaratus (H. Milne Edwards, 1834) (Decapoda: Brachyura: Xanthidae) on rocky shores in Kuwait, Arabian (Persian) Gulf

Abstract Leptodius exaratus (H. Milne Edwards, 1834) is an exploited species that has been used as bait for recreational fishing in Kuwait. The biological and ecological aspects of the species required to manage this practice are limited. We investigated the life history and population ecology of L. exaratus in the northwestern Arabian (Persian) Gulf. The spawning season of the crab in Kuwait starts in the late spring and continues through the summer and ends in September. Fecundity is highly correlated to female body size and ranges 2,533–11,991 eggs clutch–1, with a mean number of 7,055 eggs clutch–1. Juveniles are generally recruited between July and September, with lower minor recruitment levels occurring in October and November. Growth is highly seasonal, being slow during the cold season (October-February) and high during the warmer season (March and September), with a higher growth rate in males than in females. The seasonality of growth and reproduction of L. exaratus in the region is strongly related to ambient air and water temperatures. Sexual dimorphism is highly significant between males and females with males, reaching reproductive maturity at 17.43 ± 0.53 mm carapace width (CW) and females at 9.58 ± 1.21 mm CW. The overall sex ratio for the species is 0.8:1 (males:females). Furthermore, the life span of 3–4 yr and an overall mortality slightly higher in males than in females. The results of our study could be used to determine fishery management strategies such as minimum catch sizes and closures periods. The results on life history and dynamics of the complex life cycle of L. exaratus contribute to conservation and sustainable exploitation of the species in Kuwait.

Variation in reproductive traits associated with different host plants in the subsocial bug Elasmucha putoni (Hemiptera: Acanthosomatidae)

ABSTRACTHost plants are an important selective factor for the evolution of reproductive traits in herbivorous insects. Among different host plants, offspring will be exposed to different environmental conditions, and parents are expected to allocate reproductive resources adaptively to their offspring according to such environmental heterogeneity. Elasmucha putoni Scott (Hemiptera: Acanthosomatidae) is a bivoltine shield bug showing maternal care. We examined the variation in reproductive traits, that is, egg size, clutch size and the trade‐off between them, between two generations of a population and two populations of the same (later) generation, which differ in their host plants. Controlling for female body size, a significant difference was detected in egg size, but not in clutch size between the earlier generation on Morus australis and the later one on Euptelea polyandra or Rosa multiflora. Moreover, there was no difference in the two traits between the populations (one using E. polyandra and another using R. multiflora) of the same generation. A significant trade‐off between egg size and clutch size was detected in the earlier generation on M. australis but not in the later generation on E. polyandra or R. multiflora. This is the first study indicating variable reproductive allocation according to different host plants in herbivorous insects with maternal care.

Future sea-level rise impacts to Olive Ridley (Lepidochelys olivacea) and Green Sea Turtle (Chelonia mydas) nesting habitat on the Osa Peninsula, Costa Rica

Global sea turtle populations are in decline and so a global network of sea turtle nesting conservation programs have been established worldwide with the goal to protect vulnerable nesting mothers, and their clutches of eggs. Yet researchers have recently estimated that sea turtle nesting habitat is likely to suffer as a result of climate change and associated sea level rise. This study examines nest monitoring data from Costa Rica's Osa Peninsula with the aim to identify clutches located in suitable nesting habitat most susceptible to sea level rise and subsequent inundation. We analyze the impacts of six different sea level rise scenarios (from 0.25 m to 2 m) and discuss nesting inclinations and distributions of threatened Olive Ridley (Lepidochelys olivacea) and Green (Chelonia mydas) sea turtles on two beaches of the peninsula—known locally as Piro and Pejeperro. Sea-level rise scenarios on Piro beach indicated that 28.81% of the entire sample were likely to be inundated under a 0.25 m scenario, and 16.52% on Pejeperro beach. Under a more extreme, 2 m scenario, results indicated that 41.74% of nest sites on Piro and 24.55% on Pejeperro would be impacted. Results suggest that Olive Ridley turtles may be more susceptible to sea-level rise, based on their preferred nesting zones, commonly nesting closer to the tide line, as opposed to Green turtles that prefer to nest further from the tide line in vegetation zones where sea-level rise is likely to have less impact. Ultimately, the methodologies used in this study can support sea turtle conservation programs in assessing the potential effects of sea level rise and understanding nesting distributions on their nesting beaches, while also providing important insight in forecasting nest management and implementing monitoring techniques that may reduce the negative impacts associated with climate change and subsequent sea-level rise.

Frogs and flows: Using life‐history traits and a systematic review to establish water‐dependent functional groups for stream frogs in New South Wales, Australia

AbstractHydrological alteration has contributed to the global decline of stream frogs. Flows support stream frog reproduction, juvenile development, food resources, and maintain habitats for all life stages. At present, there is a lack of information regarding the specific water requirements necessary for the conservation of stream frogs. To address this gap, we developed a traits‐based approach that serves as a valuable tool for grouping and prioritising water‐dependent stream frog species to inform future research priorities and environmental flow design. In this study, we focussed on 53 Australian frog species and analysed eight species traits to develop water‐dependent functional groups for stream frogs. We classified frogs based on their level of water dependency using an agglomerative hierarchical clustering analysis and a systematic review of water requirements and water management threats. The distinguishing traits that determined functional groups were: tadpole body type, egg clutch type, stream breeding habitat type, and documented association with flowing water and water permanence. Our study identified two distinct water‐dependent groups: facultative stream spawners, capable of reproducing in both stream and non‐stream habitats, and obligate stream spawners, restricted solely to stream habitats. Importantly, we highlight that the obligate stream spawners are the most sensitive group to within‐channel flow alteration and should be prioritised for water management decisions in lotic environments. This study represents the first comprehensive overview of the importance of hydrology for stream frogs and identifies the critical need for additional research and validation to enhance our understanding of stream frog responses to flows regimes.

Fate and effects of microplastic particles in a periphyton-grazer system

In the aquatic environment, microplastic particles (MP) can accumulate in microbial communities that cover submerged substrata, i.e. in periphyton. Despite periphyton being the essential food source for grazers in the benthic zones, MP transfer from periphyton to benthic biota and its ecotoxicological consequences are unknown. Therefore, in this study, we investigated the effects of 1) MP on embryonal development of freshwater gastropod Physa acuta embryos, 2) MP on adult Physa acuta individuals through dietary exposure and 3) on the MP surface properties. Embryonal development tests were carried out with spherical polyethylene MP in the size of 1–4 μm (MP). Over a period of 28 days, embryonal development and hatching rate were calculated. In the feeding experiments, periphyton was grown in the presence and absence of MP and was then offered to the adult Physa acuta for 42–152 h. The snails readily ingested and subsequently egested MP, together with the periphyton as shown by MP quantification in periphyton, snail soft body tissue and feces. No selective feeding behavior upon MP exposure was detected. The ingestion of MP had no effect on mortality, feeding and defecation rate. Yet, the reproductive output of snails, measured as the number of egg clutches and numbers of eggs per clutch, decreased after the ingestion of MPs, while the hatching success of snail embryos those parents were exposed remained unaffected. In contrast, hatching rate of snail embryos was significantly reduced upon direct MP exposure. MP optical properties were changed upon the incorporation into the periphyton and the passage through the digestive tract. Our results indicate that MP incorporated in periphyton are bioavailable to aquatic grazers, facilitating the introduction of MP into the food chain and having direct adverse effects on the grazers’ reproductive fitness.

Pre‐loved home: Egg clutches of the striped marsh frog, Limnodynastes peronii, detected in water‐filled burrows created by the hunter hairy crayfish, Cherax setosus

AbstractMany animals create their own microhabitats that are not naturally present in the environment, such as nests and burrows, which are extended phenotypes that perform tasks related to survival and reproduction. Animals may be able to avoid the costs of implementing their own extended phenotypes by exploiting those already created by other species, including structures that are not actively in use or abandoned. Herein, we report on the striped marsh frog, Limnodynastes peronii, from Australia utilizing crayfish burrows for depositing their egg clutches. Field observations revealed large numbers of recently hatched L. peronii tadpoles in two flooded burrows likely created by the hunter hairy crayfish, Cherax setosus, near an ephemeral wetland pond on Kooragang Island, Australia that had partially dried. Our observations indicate that L. peronii may opportunistically exploit crayfish burrows which, when flooded, become suitable aquatic sites for breeding. These small waterbodies may provide fitness benefits to offspring, reducing exposure to aquatic predators found in naturally occurring aquatic systems but at the expense of increasing competition and cannibalism among confined siblings. These burrows may provide suitable microhabitat refuge during droughts, and breeding habitat for amphibians when other typical breeding habitats may not exist due to wetland drying. This is an example of an amphibian using an extended phenotype of a crustacean for the purposes of reproduction, revealing a unique interaction between these species that has not been reported.