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Although anuran tadpoles are widely distributed and abundant in tropical aquatic habitats, there is a lack of taxonomic keys for the Atlantic Forest. Herein, we developed a dichotomous key for identifying the tadpoles for all species with known larval phase and already recorded in the Atlantic Forest north of the São Francisco River. We analyzed discrete characteristics of 1,042 tadpoles encompassing 63 species of 28 genera from 32 localities. The user-friendly key includes illustration and pictures, and it is a significant step towards improving our knowledge of tadpoles of the Atlantic Forest. Resumo: Embora os girinos de anuros sejam amplamente distribuídos e abundantes em habitats aquáticos tropicais, não há chaves taxonômicas suficientes para as espécies da Mata Atlântica. Aqui, desenvolvemos uma chave dicotômica para identificar os girinos de todas as espécies com fase larval conhecida e já registradas nesse bioma, ao norte do rio São Francisco. Nós analisamos características discretas de 1.042 girinos pertencentes a 63 espécies (28 gêneros) de 32 localidades. Esta chave de identificação inclui ilustrações e imagens, sendo um passo significativo para um melhor conhecimento dos girinos da Mata Atlântica.

The pelagic larval stage is a critical component of the life cycle of most coral reef fishes, but the adaptive significance of this stage remains controversial. One hypothesis is that migrating through the pelagic environment reduces the risk a larval fish has of being parasitised. Most organisms interact with parasites, often with significant, detrimental consequences for the hosts. However, little is known about the parasites that larval fish have upon settlement, and the factors that affect the levels of parasitism. At settlement, coral reef fishes vary greatly in size and age (pelagic larval duration), which may influence the degree of parasitism. We identified and quantified the parasites of pre-settlement larvae from 44 species of coral reef fishes from the Great Barrier Reef and explored their relationship with host size and age at settlement, and phylogeny. Overall, less than 50% of the larval fishes were infected with parasites, and over 99% of these were endoparasites. A Bayesian phylogenetic regression was used to analyse host-parasite (presence and intensity) associations. The analysis showed parasite presence was not significantly related to fish size, and parasite intensity was not significantly related to fish age. A phylogenetic signal was detected for both parasite presence and intensity, indicating that, overall, closely related fish species were likely to have more similar susceptibility to parasites and similar levels of parasitism when compared to more distantly related species. The low prevalence of infection with any parasite type and the striking rarity of ectoparasites is consistent with the ‘parasite avoidance hypothesis’, which proposes that the pelagic phase of coral reef fishes results in reduced levels of parasitism.

The final instar larva of Synergus filicornis (Cameron) (Hymenoptera: Cynipidae: Synergini) is described and illustrated. Morphological structures of a diagnostic value are discussed. The most remarkable character states shown by the mature larva of this species lie in the integument, which unlike the rest of described cynipoid mature larvae, presents tegumental differentiations. Additionally the antennal orbits, unlike those of other described Synergini mature larvae, did not present one seta on each antennal orbit. The immature larvae can be differentiated from the mature larva by the following characters: a) number and location of sensorial tegumental differentiations on the head, b) number of sensilla on the maxillary palpi, and c) morphology of the mandibles. The determination of the mandibles size, in this species, permits the estimation of the larval stages number.

This chapter contains sections titled: Introduction Broodstock management Larval rearing Raising wild‐caught pueruli and juveniles Future developments References

In order to determine the early life history and recruitment mechanisms of tropical eels Anguilla spp. in the Indo-Pacific, the timing of metamorphosis and age at recruitment to freshwater habitats were established from otolith microstructure and microchemistry analyses of juveniles of Anguilla celebesensis, A. marmorata and A. bicolor bicolor. Otolith increment width markedly increased from the age of 124 ± 12.0 d (mean ± SD) in A. celebesensis, 120 ± 13.0 d in A. marmorata (Philippines), 120 ± 15.6 d in A. marmorata (Indonesia) and 139 ± 15.9 d in A. bicolor bicolor. The timing of these increases was coincident with drastic decreases in otolith Sr:Ca ratios in each species, indicating the onset of metamorphosis from leptocephalus to glass eel. The mean duration of metamorphosis was 17 to 18 d in each species. Age at recruitment (mean ± SD) was 157 ± 13.7 d in A. celebesensis, 154 ± 13.5 d in A. marmorata (Philippines), 152 ± 15.2 d in A. marmorata (Indonesia) and 177 ± 16.4 d in A. bicolor bicolor. In all species examined, close linear relationships were found between ages at metamorphosis and recruitment, suggesting that individuals which metamorphosed earlier were recruited to freshwater habitats at a younger age.

Moonlight mediates trophic interactions and shapes the evolution of life-history strategies for nocturnal organisms. Reproductive cycles and important life-history transitions for many marine organisms coincide with moon phases, but few studies consider the effects of moonlight on pelagic larvae at sea. We evaluated effects of moonlight on growth of pelagic larvae of a temperate reef fish using “master chronologies” of larval growth constructed from age-independent daily increment widths recorded in otoliths of 321 individuals. We found that daily growth rates of fish larvae were enhanced by lunar illumination after controlling for the positive influence of temperature and the negative influence of cloud cover. Collectively, these results indicate that moonlight enhances growth rates of larval fish. This pattern is likely the result of moonlight’s combined effects on foraging efficiency and suppression of diel migrations of mesopelagic predators, and has the potential to drive evolution of marine life histories.

We examined the planktonic ingress of fiddler crab megalopae into the Newport River Estuary, NC, using hog’s hair collectors to determine whether there were differences in patterns of ingress among the 3 Uca species in this estuary. In 2 consecutive summers, we documented peaks in settlement of fiddler crab megalopae onto passive larval collectors at the quarter moons (neap tides), corresponding with longer durations of flood tides during darkness. However, molecular identifications revealed that over 80% of the megalopae settling on collectors were U. pugnax, even though there are millions of U. pugilator on sandflats within 1 km of the collection site and U. minax are common in the estuary. Plankton net samples taken on the same nights as collector settlement confirmed that megalopae of all 3 Uca species are common in the plankton. The proportions of species in the plankton and settling on collectors were significantly different. These differences may reflect species-specific differences in thigmotactic behavior, or may indicate differences in times of transport within a tide, since collectors reflect settlement at the end of rising tide while plankton nets sample the abundance at the time of maximum flood tide current. Thus, hog’s hair collectors may not be an unbiased sampling method for fiddler crab megalopae.

Several recent high intensity ENSO events have caused strong negative impacts on the adult phases of foundational species in coral reef ecosystems, but comparatively little is known about how climatic variables related to recent ENSOs are impacting the supply of larvae to benthic populations. In marine fishes and invertebrates, reproductive adults and planktonic larvae are generally more sensitive to environmental variability than older, non-reproductive adults. Further, the transport of larvae in ocean currents may also be strongly ENSO dependent. The interactions between the dynamics of larval survivorship and larval transport could lead to population bottlenecks as stronger ENSO events become more common. We tested the predictions of this hypothesis around the Main Hawaiian Islands (MHI) by constructing a correlation matrix of physical and biological time series variables that spanned 11 years (2007–2017) and multiple ENSO events. Our correlation matrix included four types of variables: i. published ENSO indices, ii. satellite-derived sea surface temperature (SST) and chlorophyll variables, iii. abundance and diversity of larval fishes sampled during the late winter spawning season off Oahu, and iv. abundance and diversity of coral reef fish recruits sampled on the western shore of the Big Island of Hawaii. We found that the abundance and diversity of larval fishes was negatively correlated with the Multivariate El Niño Index (MEI), and that larval variables were positively correlated with measures of fall recruitment (September & November), but not correlated with spring-summer recruitment (May & July). In the MHI, SST variables were not correlated with the MEI, but two successive El Niño events of 2014–15 and 2015–2016 were characterized by SST maxima approaching 30°C. Two large pulses of benthic recruitment occurred in the 2009 and 2014 recruitment seasons, with > 8000 recruits observed by divers over the summer and fall months. Both events were characterized by either neutral or negative MEI indices measured during the preceding winter months. These patterns suggest that La Niña and the neutral phases of the ENSO cycle are generally favorable for adult reproduction and larval development in the spring and summer, while El Niño phases may limit recruitment in the late summer and fall. We hypothesize that episodic recruitment during non-El Niño phases is related to favorable survivorship and transport dynamics that are associated with the formation of pairs of anticyclonic and cyclonic eddies on the leeward sides (western shores) of the Main Hawaiian Islands.

The final body size of any given individual underlies both genetic and environmental constraints. Both mammals and insects use target of rapamycin (TOR) and insulin signaling pathways to coordinate growth with nutrition. In holometabolous insects, the growth period is terminated through a cascade of peptide and steroid hormones that end larval feeding behavior and trigger metamorphosis, a nonfeeding stage during which the larval body plan is remodeled to produce an adult. This irreversible decision, termed the critical weight (CW) checkpoint, ensures that larvae have acquired sufficient nutrients to complete and survive development to adulthood. How insects assess body size via the CW checkpoint is still poorly understood on the molecular level. We show here that the Drosophila transcription factor Snail plays a key role in this process. Before and during the CW checkpoint, snail is highly expressed in the larval prothoracic gland (PG), an endocrine tissue undergoing endoreplication and primarily dedicated to the production of the steroid hormone ecdysone. We observed two Snail peaks in the PG, one before and one after the molt from the second to the third instar. Remarkably, these Snail peaks coincide with two peaks of PG cells entering S phase and a slowing of DNA synthesis between the peaks. Interestingly, the second Snail peak occurs at the exit of the CW checkpoint. Snail levels then decline continuously, and endoreplication becomes nonsynchronized in the PG after the CW checkpoint. This suggests that the synchronization of PG cells into S phase via Snail represents the mechanistic link used to terminate the CW checkpoint. Indeed, PG-specific loss of snail function prior to the CW checkpoint causes larval arrest due to a cessation of endoreplication in PG cells, whereas impairing snail after the CW checkpoint no longer affected endoreplication and further development. During the CW window, starvation or loss of TOR signaling disrupted the formation of Snail peaks and endocycle synchronization, whereas later starvation had no effect on snail expression. Taken together, our data demonstrate that insects use the TOR pathway to assess nutrient status during larval development to regulate Snail in ecdysone-producing cells as an effector protein to coordinate endoreplication and CW attainment.

Predation during the downstream dispersal of larval stages represents a major recruitment bottleneck for fish populations. The co-occurrence of other organisms in river drift may reduce predation, but our knowledge of the factors influencing the composition and abundance of drift communities during post-hatch dispersal of larval fish remain limited. A multi-year (2011–2018) study was conducted to investigate abiotic factors influencing drift communities during larval lake sturgeon (Acipenser fulvescens) dispersal in the Upper Black River (Cheboygan, MI, USA). Cumulative water temperature was a strong predictor of drift for larval lake sturgeon, suckers (Catostomidae) and macroinvertebrates, with reduced macroinvertebrate drift during lunar phases with higher lunar illumination. Nights with a new moon had on average, three times the drifting macroinvertebrate biomass as nights during a full moon, with Heptageniidae and Isonychiidae displaying higher abundances during lower light conditions. Favorable conditions for other taxa to reduce larval lake sturgeon predation through predator swamping were common, though variability in timing (overlap between drifting taxa), biomass, and abundances likely alters the strength of such effects among years. A better understanding of the conditions influencing drifting communities during larval fish dispersal may assist in predicting larval mortality and year-class strength for managed fish populations.