Larval Diversity Research Articles

Morphology of lecithotrophic postlarvae of genus Austropallene (Arthropoda: Chelicerata) with some notes on reproductive strategy

The family Callipallenidae Hilton, 1942 belongs to the superfamily Nymphonoidea Pocock, 1904 together with other family, Nymphonidae. The lecithotrophic postlarvae hatch from the eggs of the callipallenid sea spiders, but the data on this life stage are very scarce and fragmentary. This gives a very limited understanding of larval anatomy, morphology, and diversity. The larvae of Austropallene bucera Pushkin, 1993, Austropallene calmani Gordon, 1944, and Austropallene cristata Bouvier, 1911 have been studied and described for the first time by the methods of light (LM) and scanning electron microscopy (SEM). The main morphometry parameters have been determined in larvae and adult egg-bearing males. The general plan of the postlarvae is presented together with its specific features. The postlarvae of the studied Austropallene species combine the features of lecithotrophic and free-living pycnogonid larvae. The diversity of larvae in the Nymphonoidea superfamily has been analysed considering original and published data, and a morphological series has been developed. The complex of lecithotrophic larvae, like postlarvae of Callipallenidae, should be considered as primary for the entire superfamily. It is also suggested that sea spiders with lecithotrophic larvae tend to follow the K-strategy, but they care for their offspring to varying degrees.

The Diversity of Larvae with Multi-Toothed Stylets from About 100 Million Years Ago Illuminates the Early Diversification of Antlion-like Lacewings

Neuroptera, the group of lacewings, is well known to have been more diverse in the past, offering to study patterns of biodiversity loss over time. This loss of diversity has been quantitatively established by the morphological diversity of lacewing larvae. Here, we explore in more detail the diversity of lacewing larvae with tooth-bearing mouthparts. All these larvae are representatives of Myrmeleontiformia, the group of antlion-like lacewings. Today, larvae of several major ingroups bear teeth on their mouthparts: (1) owllions (formerly Ascalaphidae and Myrmeleontidae; taxonomic status is currently unclear); (2) Nymphidae; (3) Crocinae (mostly in younger larvae); and (4) Nemopterinae (only micro teeth). In addition, there are several now extinct larval types with teeth known from Cretaceous ambers (about 100 million years old). These larvae also possess several plesiomorphic characters, indicating that they were part of the early diversification of Myrmeleontiformia. We report numerous new specimens of these now extinct forms and provide a quantitative morphological comparison of head and mouthpart shapes, demonstrating that some of these Cretaceous larvae possessed morphologies not represented in the extant fauna. The resulting pattern is complex, indicating that at least some extinct morphologies have been later replaced by modern-day antlions due to convergent evolution.

Single-specimen systematics resolves the phylogeny and diversity conundrum of enigmatic crustacean y-larvae

Resolving the evolutionary history of organisms is a major goal in biology. Yet for some taxa the diversity, phylogeny, and even adult stages remain unknown. The enigmatic crustacean “y-larvae” (Facetotecta) are one particularly striking example. Here, we use extensive video-imaging and single-specimen molecular sequencing of >200 y-larval specimens to comprehensively explore for the first time their evolutionary history and diversity. This integrative approach revealed five major clades of Facetotecta, four of which encompass a considerable larval diversity. Whereas morphological analyses recognized 35 y-naupliar “morphospecies”, molecular species-delimitation analyses suggested the existence of between 88 and 127 species. The phenotypic and genetic diversity between the morphospecies suggests that a more elaborate classification than the current one-genus approach is needed. Morphology and molecular data were highly congruent at shallower phylogenetic levels, but no morphological synapomorphies could be unambiguously identified for major clades, which mostly comprise both planktotrophic and lecithotrophic y-nauplii. We argue that lecithotrophy arose several times independently whereas planktotrophic y-nauplii, which are structurally more similar across clades, most likely display the ancestral feeding mode of Facetotecta. We document a remarkably complex and highly diverse phylogenetic backbone for a taxon of larval marine crustaceans, the full life cycle of which remains a mystery.

Gut microbiota is a potential factor in shaping phenotypic variation in larvae and adults of female bumble bees.

Host symbionts are often considered an essential part of the host phenotype, influencing host growth and development. Bumble bee is an ideal model for investigating the relationship between microbiota and phenotypes. Variations in life history across bumble bees may influence the community composition of gut microbiota, which in turn influences phenotypes. In this study, we explored gut microbiota from four development stages (early-instar larvae, 1st instar; mid-instar larvae, 5th instar; late-instar larvae, 9th instar; and adults) of workers and queens in the bumble bee Bombus terrestris using the full-length 16S rRNA sequencing technology. The results showed that morphological indices (weight and head capsule) were significantly different between workers and queens from 5th instar larvae (p < 0.01). The alpha and beta diversities of gut microbiota were similar between workers and queens in two groups: early instar and mid instar larvae. However, the alpha diversity was significantly different in late instar larvae or adults. The relative abundance of three main phyla of bacteria (Cyanobacteria, Proteobacteria, and Firmicutes) and two genera (Snodgrassella and Lactobacillus) were significantly different (p < 0.01) between workers and queens in late instar larvae or adults. Also, we found that age significantly affected the microbial alpha diversity as the Shannon and ASVs indices differed significantly among the four development stages. Our study suggests that the 5th instar larval stage can be used to judge the morphology of workers or queens in bumble bees. The key microbes differing in phenotypes may be involved in regulating phenotypic variations.

Marked Effects of Larval Salt Exposure on the Life History and Gut Microbiota of the Malaria Vector Anopheles merus (Diptera: Culicidae).

Anopheles merus can breed in a range of saltwater concentrations. The consequences of this ability on the life history of adult An. merus are poorly understood. This study examined the effects of exposure to 0, 2.1875, 4.375, 8.75, and 17.5 g/L of sodium chloride on An. merus. The effects on larval development, adult longevity, fertility, and fecundity, as well as deltamethrin tolerance were examined. The effect of larval salt exposure on the expression of defensin-1 in adults was examined by quantitative Real-Time PCR. Finally, the effect of the larval salt concentration on microbial dynamics was assessed by 16S Next Generation Sequencing. High concentrations of saltwater increased larval development time and number of eggs laid, as well as deltamethrin tolerance. Larval exposure to salt also reduced the expression of defensin-1. The exposure also had a significant effect on microbial diversity in larvae and adults. The diversity of larvae decreased once adults emerged. Salt-tolerant bacterial genera predominated in larvae but were absent in adults. High salt concentrations resulted in greater abundance of Plasmodium-protective genera in adults. Although this study was conducted on a laboratory strain of An. merus, these data suggest that osmoregulation has a significant effect on the life history of the species with potential epidemiological consequences.

Identifying drivers of tropical riverine larval fish abundance and diversity

Several hypotheses and conceptual models propose to explain mechanisms mediating riverine fish abundance, but few empirical studies to date have explored their utility in tropical systems. This study assesses key components of previous fish recruitment models by exploring spatiotemporal variation in larval fish assemblages in response to predicted key drivers in a tropical Australian river catchment. Data on larval fish composition and abundance, alongside hydrological, hydraulic, habitat and food variables, were collected monthly to bimonthly over one year at eight sites. Variables which best predicted larval fish abundance and diversity were determined with Boosted Regression Trees. The most commonly important predictors were microfauna abundance, structural habitat complexity and temperature, with high values of each predicting high larval fish abundance and diversity. Maximum larval diversity occurred when discharge was highest because several wet-season spawning taxa occurred alongside aseasonally spawning taxa. These findings support previous generic fish recruitment models, demonstrating the utility of their inclusion in the recent Riverine Recruitment Synthesis Model and the applicability of this model for describing processes important for tropical riverine fish recruitment.

Temporal variation in abundance of bully sleepers (Pisces: Eleotridae) larvae and juveniles in Cisolok Estuary, Palabuhanratu Bay, Indonesia

Larvae and juveniles of bully sleepers are the primary targets for the local community surrounding Cisolok River, and this traditional fishing activity is called nyalawean. The present study aims to uncover fish larval diversity and recruitment of bully sleepers in the Cisolok river estuary. Fish sampling using a lift net was conveyed monthly from December 2020 to February 2021. Fish specimens were identified to the lowest taxon through a morphological approach and DNA Barcoding. Catch per unit effort measured the abundance of fish larvae and juveniles (CPUE, Ind.h−1). Only one species was found during the study period, namely Bunaka gyrinoides. A total of 7,353 larvae and juveniles of B. gyrinoides were captured, consisting of flexion (45 individuals; 4-5.9 mm BL), postflexion (6,887; 6-11 mm BL), and early juvenile (441; 11.1-14.8 mm BL). Postflexion larvae were the most abundant specimens, contributing 88.4-95.5%; 96-81.1%, 94.2-97.8% to the total catches in December, January, and February. Larvae and juveniles were more abundant during daylight (671-1591 Ind.h-1) rather than nighttime (147-567 Ind.h-1). These findings indicate that bully sleepers recruit and migrate upstream into the freshwater area of the Cisolok River during the day and nighttime synchronized with the tidal fluxes.

Phenotypic Variation Through Ontogeny: Thyroid Axis Disruption During Larval Development in the Frog Pleurodema borellii

Studies of the effects of thyroid hormones on larval development in the frog Xenopus spp. have provided baseline information to identify developmental constraints and elucidate genetic and hormonal mechanisms driving development, growth, and life history transitions. However, this knowledge requires data based on other anurans to complete a comprehensive approach to the understanding of larval developmental diversity and phenotypic variation through ontogeny. Mesocosm experiments provide realistic data about environmental conditions and timing; this information is useful to describe anuran larval development and/or analyze endocrine disruption. In this study, mesocosm experiments of the larval development of the frog Pleurodema borellii were conducted to explore the consequences of thyroid axis disruption; the sensitivity of tadpoles to the methimazole (2.66 mg/l) and thyroxine (T4) (1.66 μg/l) was compared. These concentrations were selected based on previous studies in Pleurodema borellii. We test the effects of methimazole and thyroxine on development in early exposure (from beginning of larval development) and late exposure, 18 days after hatching, with doses administered every 48 h. Tadpoles were evaluated 31 days after hatching. Methimazole caused moderate hypertrophy of the thyroid gland, alteration in the growth rates, differentiation without inhibition of development, and an increase of developmental variability. Thyroxine produced slight atrophy of the thyroid gland, accelerated growth rates and differentiation, and minor developmental variability. In tadpoles at stages previous to metamorphose, skull development (differentiation of olfactory capsules, appearance of dermal bones, and cartilage remodeling) seemed to be unaltered by the disruptors. Moreover, similar abnormal morphogenesis converged in specimens under methimazole and thyroxine exposures. Abnormalities occurred in pelvic and pectoral girdles, and vent tube, and could have been originated at the time of differentiation of musculoskeletal tissues of girdles. Our results indicate that premetamorphic stages (Gosner Stages 25–35) are sensitive to minimal thyroid axis disruption, which produces changes in developmental rates; these stages would also be critical for appendicular musculoskeletal morphogenesis to achieve the optimal condition to start metamorphosis.

Spatial and Temporal Patterns of Pelagic Catfish Larvae Drifting in Lowland Rivers of Eastern Ecuador (Pisces: Siluriformes)

This study investigated larval catfish abundance and diversity in various fluvial habitats in the Amazon lowlands of eastern Ecuador. It assessed the relationship between spawning behavior and the hydrological cycle, identified a potential spawning site, and elucidated community assemblages based on larval diversity among river tributaries with differing water chemistry profiles. Sampling sites included the mainstreams of the Napo and Aguarico Rivers and lower reaches of three tributaries. Drift samples were taken before, during, and after strong, rain-induced flooding occurred. Results suggest a strong peak of larval abundances in April, coinciding with the start of the flood period. In the Napo mainstream, samples were dominated by larvae of large migratory pimelodid catfishes, Pseudoplatystoma spp., which were caught between the upriver site in the foothills (254 m a.s.l.) and the downstream Peruvian frontier (175 m a.s.l.). Back-calculations based on water velocity and larval growth rate suggest that most of these larvae originated in the lowlands between those two locations, where the riverbed transitions from rocky to sandy/silty substrate. Thus, it appears that most spawning occurred over sandy substrates rather than the rocky substrates that were dominant above the upriver site. Comparisons of samples taken by day and night at the same sites revealed significantly higher larval abundances at night; thus, larvae must either preferentially drift at night, actively avoid the nets by day, or may do diel vertical migrations (e.g., related to predation pressure or pursuit of prey items). Dominant larval taxa in the whitewater mainstreams differed from those dominating samples from a blackwater mainstream system, and catfish larval assemblages in each of those habitats were distinct from those drifting in small, blackwater tributaries. These results provide key life-history information for catfish species in the Napo River, including for important commercial species, such as Pseudoplatystoma spp. Identification and protection of discrete spawning sites, such as those identified here, are critical to conservation efforts for these species.

Changes in the Morphological Diversity of Larvae of Lance Lacewings, Mantis Lacewings and Their Closer Relatives over 100 Million Years.

Simple SummaryAmong insects, the group Neuroptera (lacewings) appears to be less well known to most people, at least in comparison to beetles, butterflies, or wasps. Nowadays, about 6000 species of lacewings are known, but the fossil record yields a large number of further representatives, hinting to a possibly larger role lacewings played in ecosystems of the past. Especially the larvae of lacewings (most prominent examples are antlions) exhibit a large morphological diversity, with fossils exhibiting many peculiar morphologies not known from the modern fauna. Lacewing larvae are well recognisable as such by their prominent jaws, also called stylets. In this study, we analysed the change of larval diversity in different lacewing groups based on the shape of these stylets together with the heads. Our results point to a complex pattern of diversity changes in Neuroptera from 100 million years ago until today.Neuroptera, the group of lacewings, comprises only about 6000 species in the modern fauna, but is generally assumed to have been more diverse and important in the past. A major factor of the modern-day ecological diversity of the group, and supposedly in the past as well, is represented by the highly specialised larval forms of lacewings. Quantitative analyses of the morphology of larvae revealed a loss of morphological diversity in several lineages. Here we explored the diversity of the larvae of mantis lacewings (Mantispidae), lance lacewings (Osmylidae), beaded lacewings (Berothidae and Rhachiberothidae, the latter potentially an ingroup of Berothidae), and pleasing lacewings (Dilaridae), as well as fossil larvae, preserved in amber, resembling these. We used shape analysis of the head capsule and stylets (pair of conjoined jaws) as a basis due to the high availability of this body region in extant and fossil specimens and the ecological importance of this region. The analysis revealed a rather constant morphological diversity in Berothidae. Mantispidae appears to have lost certain forms of larvae, but has seen a drastic increase of larval diversity after the Cretaceous; this is in contrast to a significant decrease in diversity in adult forms.

A Mysterious World Revealed: Larval-Adult Matching of Deep-Sea Shrimps from the Gulf of Mexico

The identification of deep-sea (&gt;200 m) pelagic larvae is extremely challenging due to the morphological diversity across ontogeny and duration of larval phases. Within Decapoda, developmental stages often differ conspicuously from their adult form, representing a bizarre and mysterious world still left to be discovered. The difficulties with sampling and rearing deep-sea larvae, combined with the lack of taxonomic expertise, argues for the use of molecular methods to aid in identification. Here, we use DNA barcoding combined with morphological methods, to match larval stages with their adult counterpart from the northern Gulf of Mexico and adjacent waters. For DNA barcoding, we targeted the mitochondrial ribosomal large subunit 16S (16S) and the protein coding cytochrome oxidase subunit 1 (COI). These data were combined with previous sequences to generate phylogenetic trees that were used to identify 12 unknown larval and two juvenile species from the infraorder Caridea and the suborder Dendrobranchiata. Once identified, we provide taxonomic descriptions and illustrations alongside the current state of knowledge for all families. For many groups, larval descriptions are missing or non-existent, so this study represents a first step of many to advance deep-sea larval diversity.

Diel and Tidal Variations of Larvae and Juveniles of Metapenaeus dobsoni from Sundarbans Estuarine System, India

Diel and Tidal Variations of Larvae and Juveniles of Metapenaeus dobsoni from Sundarbans Estuarine System, India

Genetic connectivity between Atlantic bluefin tuna larvae spawned in the Gulf of Mexico and in the Mediterranean Sea.

The highly migratory Atlantic bluefin tuna (ABFT) is currently managed as two distinct stocks, in accordance with natal homing behavior and population structuring despite the absence of barriers to gene flow. Larval fish are valuable biological material for tuna molecular ecology. However, they have hardly been used to decipher the ABFT population structure, although providing the genetic signal from successful breeders. For the first time, cooperative field collection of tuna larvae during 2014 in the main spawning area for each stock, the Gulf of Mexico (GOM) and the Mediterranean Sea (MED), enabled us to assess the ABFT genetic structure in a precise temporal and spatial frame exclusively through larvae. Partitioning of genetic diversity at nuclear microsatellite loci and in the mitochondrial control region in larvae spawned contemporarily resulted in low significant fixation indices supporting connectivity between spawners in the main reproduction area for each population. No structuring was detected within the GOM after segregating nuclear diversity in larvae spawned in two hydrographically distinct regions, the eastern GOM (eGOM) and the western GOM (wGOM), with the larvae from eGOM being more similar to those collected in the MED than the larvae from wGOM. We performed clustering of genetically characterized ABFT larvae through Bayesian analysis and by Discriminant Analysis of Principal Components (DAPC) supporting the existence of favorable areas for mixing of ABFT spawners from Western and Eastern stocks, leading to gene flow and apparent connectivity between weakly structured populations. Our findings suggest that the eastern GOM is more prone for the mixing of breeders from the two ABFT populations. Conservation of this valuable resource exploited for centuries calls for intensification of tuna ichthyoplankton research and standardization of genetic tools for monitoring population dynamics.

Composition and diversity of larval fish in the Indian Ocean using morphological and molecular methods

Although vital in fisheries management, no comprehensive studies on ichthyoplankton have been conducted in Sri Lankan waters in the north central Indian Ocean hitherto. Hence, this study is the first detailed account of diversity and species composition of larval fish based on samples collected during the southwest monsoon in 2018. In total, 80 species belonging to 69 families were identified using morphological and molecular methods targeting the COI gene. The larval fish diversity varied significantly between regions: east (North East, Central East, and South East) and west (North West, South West, and South). In their larval stages, mesopelagic families were associated with the offshore waters whereas demersal and pelagic families were related with shelf regions in the South, South East, and Central East. The larvae of pelagic families are likely dispersed by the South Monsoon Current from the west to the east regions, while demersal fish seem to be confined to the same area as conspecific adults. The most abundant larval species observed were Selar crumenophthalmus, Cubiceps pauciradiatus, and Dipterygonotus balteatus. High abundances of several commercially important larval tuna species were found in the South East, Central East, and South regions indicating that these waters could be important nursery grounds. Furthermore, Callionymus simplicicornis was recorded for the first time in the Indian Ocean, and seven additional species were found new to Sri Lankan waters. The results from this study also highlight the importance of using combined morphological and molecular methods and the need for strengthening fish nucleotide databases in poorly studied areas of the Indian Ocean.

Dynamics of the bacterial gut microbiota during controlled human infection with Necator americanus larvae

ABSTRACT Hookworms are soil-transmitted helminths that use immune-evasive strategies to persist in the human duodenum where they are responsible for anemia and protein loss. Given their location and immune regulatory effects, hookworms likely impact the bacterial microbiota. However, microbiota studies struggle to deconvolute the effect of hookworms from confounders such as coinfections and malnutrition. We thus used an experimental human hookworm infection model to explore temporal changes in the gut microbiota before and during hookworm infection. Volunteers were dermally exposed to cumulative dosages of 50, 100 or 150 L3 Necator americanus larvae. Fecal samples were collected for microbiota profiling through 16S rRNA gene amplicon sequencing at weeks zero, four, eight, fourteen and twenty. During the acute infection phase (trial week zero to eight) no changes in bacterial diversity were detected. During the established infection phase (trial week eight to twenty), bacterial richness (Chao1, p = .0174) increased significantly over all volunteers. No relation was found between larval dosage and diversity, stability or relative abundance of individual bacterial taxa. GI symptoms were associated with an unstable microbiota during the first eight weeks and rapid recovery at week twenty. Barnesiella, amongst other taxa, was more abundant in volunteers with more GI symptoms throughout the study. In conclusion, this study showed that clinical GI symptoms following N. americanus infection are associated with temporary microbiota instability and relative abundance of specific bacterial taxa. These results suggest a possible role of hookworm-induced enteritis on microbiota stability.

Histo‐morphology of the thyroid gland during the larval development of Pleurodema borellii (Anura, Leptodactylidae)

AbstractThe thyroid gland is essential in anurans, since thyroid hormones (TH) are the main regulators of larval development. Its absence or inactivity interrupts development and precludes metamorphosis. Histological changes are important diagnostic criteria for evaluating thyroid gland activity. However, there is a large larval diversity where the development of the thyroid gland development has not been studied. Pleurodema borellii is an anuran from northwest of Argentina with typical omnivorous pond tadpoles that can be easily raised in captivity. This study explores the histo‐morphological changes of the thyroid gland architecture during larval development. Histological parameters indicate peak glandular activity in parallel with the intensity of the metamorphic transformations. These parameters regress towards the end of metamorphosis, indicating low TH release. P. borellii's thyroid gland does not appear to have relevant activity in post‐metamorphic juvenile stages. This study is a first step towards understanding endocrine regulation during the development of Pleurodema borellii, and a reference to future studies in this species involving thyroid‐dependent processes.

Entomofaunal survey and larvicidal activity of greener silver nanoparticles: A perspective for novel eco-friendly mosquito control.

The entomofaunal survey and its toxicity of Blumea mollis (Asteraceae) leaf aqueous extract-mediated (Bm-LAE) silver nanoparticles (AgNPs) were assessed against selected human vector mosquitoes (HVMs). A total of 1800 individuals of 29 species belongs to 7 genera were identified. Month-wise and Genus-wise abundance of HVMs larval diversity were calculated and one-way ANOVA statistically analyzed the average physico-chemical characteristics. The relationship between physicochemical characteristics and HVMs larvae in KWS was interpreted. The total larval density and container index were 23530.18 and 1961.85 examined against 10 different containers. Various spectroscopic and microscopic investigation characterized Bm-AgNPs. The Bm- AgNPs tested against HVMs larvae, the predominant LC50/LC90 values of 18.17/39.56, 23.45/42.49 and 21.82/40.43 μg/mL were observed on An. subpictus Cx. vishnui and Ae. vittatus, respectively. The findings of this investigation, improperly maintained drainages, containers and unused things in study sites, are engaged to HVMs development. This will be essential for designing and implementing HVMs control. The larval toxic potentiality of Bm- AgNPs had a prompt, inexpensive and compelling synthesis of multi-disperse action against HVMs.

Carryover effects of brooding conditions on larvae in the slipper limpet Crepidula fornicata

Larval dispersal is a critical step in the life-histories of sessile benthic invertebrates. There is a growing body of research showing plasticity in marine invertebrate larvae, but the causes and ranges of intraspecific variation in larvae are not completely understood. In this study, field-based collections of Crepidula fornicata larvae in 2017 motivated a laboratory experiment on carryover effects in 2019. Experimental conditions that approximated environmental conditions experienced by mothers in the field were used to test whether seasonal environmental variations during brooding could lead to differences in larval size and the time to develop to competency. Mothers were kept in 2 different temperature and feeding treatments during brooding, but larvae were cultured in a common garden. Larvae that were brooded at spring temperatures (~13°C) took longer to develop to competency in the common garden and grew larger before becoming competent than larvae brooded at warmer summer temperatures (~21°C). There was no effect of maternal feeding (fed or not fed) on time to develop to competency or larval size. Thus, C. fornicata larvae released earlier in the year are likely to spend longer periods in the water column. They may disperse farther and grow to larger size before settlement. C. fornicata is a model species for larval biology. The results of this study can be used to inform biophysical modelling efforts and refine predictions of connectivity or species range shifts in a changing climate.

DNA barcoding of echinopluteus larvae uncovers cryptic diversity in neotropical echinoids

AbstractSurveys of larval diversity consistently increase biodiversity estimates when applied to poorly documented groups of marine invertebrates such as phoronids and hemichordates. However, it remains to be seen how helpful this approach is for detecting unsampled species in well‐studied groups. Echinoids represent a large, robust, well‐studied macrofauna, with low diversity and low incidence of cryptic species, making them an ideal test case for the efficacy of larval barcoding to discover diversity in such groups. We developed a reference dataset of DNA barcodes for the shallow‐water adult echinoids from both coasts of Panama and compared them to DNA sequences obtained from larvae collected primarily on the Caribbean coast of Panama. We sequenced mitochondrial cytochrome c oxidase subunit I (COI) for 43 species of adult sea urchins to expand the number and coverage of sequences available in GenBank. Sequences were successfully obtained for COI and 16S ribosomal DNA from 272 larvae and assigned to 17 operational taxonomic units (OTUs): 4 from the Pacific coast of Panama, where larvae were not sampled as intensively, and 13 from the Caribbean coast. Of these 17 OTUs, 13 were identified from comparisons with our adult sequences and belonged to species well documented in these regions. Another larva was identified from comparisons with unpublished sequences in the Barcode of Life Database (BOLD) as belonging to Pseudoboletia, a genus scarcely known in the Caribbean and previously unreported in Panama. Three OTUs remained unidentified. Based on larval morphology, at least two of these OTUs appeared to be spatangoids, which are difficult to collect and whose presence often goes undetected in standard surveys of benthic diversity. Despite its ability to capture unanticipated diversity, larval sampling failed to collect some species that are locally common along the Caribbean coast of Panama, such as Leodia sexiesperforata, Diadema antillarum, and Clypeaster rosaceus.

Foresight Workshop on Advances in Ocean Biological Observations: a sustained system for deep-ocean meroplankton

Recent advances in technology have enabled an unprecedented development of underwater research, extending from near shore to the deepest regions of the globe. However, monitoring of biodiversity is not fully implemented in political agendas and biological observations in the deep ocean have been even more limited in space and time. The Foresight Workshop on Advances in Ocean Biological Observations: a sustained system for deep-ocean meroplankton was convened to to foster advances in the knowledge on deep-ocean invertebrate larval distributions and improve our understanding of fundamental deep-ocean ecological processes such as connectivity and resilience of benthic communities to natural and human-induced disturbance. This Meroplankton Observations Workshop had two specific goals: 1) review the state-of-the-art instrumentation available for meroplankton observations; 2) develop a strategy to implement technological innovations for in-situ meroplankton observation. Presentations and discussions are summarised in this report covering: i) key challenges and priorities for advancing the knowledge of deep-sea larval diversity and distribution: ii) recent developments in technology and future needs for plankton observation, iii) data integration and oceanographic modelling; iv) synergies and added value of a sustained observation system for meroplankton; v) steps for developing a sustained observation system for deep-ocean meroplankton and plans to maximise collaborative opportunities.