Planktonic Larval Stage Research Articles

Находки молоди двустворчатого моллюска Crassostrea gigas (Thunberg, 1793) в озере Донузлав и в Артиллерийской бухте (Крым, Чёрное море)

Найдены и сфотографированы молодые экземпляры двустворчатого моллюска Crassostrea gigas (Thunberg, 1793), осевшие на искусственные и естественные субстраты в озере Донузлав и в Артиллерийской бухте. В этих акваториях до настоящего времени личинки C. gigas в планктоне не обнаружены.

Genetic diversity and demographic history of the endemic Southeastern Pacific sea urchin Arbacia spatuligera (Valenciennes 1846)

The pattern of the genetic structuring of marine species result from the relationship between homogenizing and structuring factors, together with historical and contemporary processes. Dispersal potential has been described as a homogenizing factor, corroborated by the connectivity paradigm, which states that high dispersers show low or no genetic differentiation. In contrast, biogeographic breaks and oceanic currents have an important role in limiting or enhancing connectivity, being structuring factors. We studied this relationship in Arbacia spatuligera, a subtidal echinoid with a planktonic larval stage, which is distributed along the Southeastern Pacific (SEP). The SEP is divided into two biogeographic provinces with an Intermediate Area between both them, which is delimited by two biogeographic breaks (~30° S and 40°-42° S). Moreover, much of the SEP coast, from ~42° S to 6° S, it is influenced by a complex system of marine currents known as the Humboldt Current System (HCS). Using molecular tools (mtDNA COI) we assessed the genetic diversity and structure of A. spatuligera and inferred its demographic history. Analyses showed that along ca. 3.200 km A. spatuligera has no genetic structure signals, has an unexpected low genetic diversity and a signal of recent demographic expansion dated ~33000 - 47000 years ago, probably related to the Marine Isotope Stage 3 (MIS3) climatic events. Our results support the hypothesis that dispersal potential is a determining factor of the phylogeographic patterns in the SEP, probably influenced by HCS. We propose that A. spatuligera is a high disperser.

Rapid larval growth is costly for post-metamorphic thermal performance in a Great Barrier Reef fish

Most marine fish species disperse during a planktonic larval stage where individuals exhibit variation in pelagic duration, growth rate and settlement size. Extreme predation risk is predicted to select for rapid growth rates and decreased pelagic duration as a strategy for increasing survival to settlement. How larval traits affect post-metamorphic performance, however, has been a contentious topic over the past 50 yrs. Some studies suggest that larval traits have carry-over effects to later life stages, where larval traits can be positively or negatively correlated with post-metamorphic performance. For example, individuals with rapid larval growth rates may settle at larger sizes and have faster post-metamorphic locomotion than slow-growing individuals. Alternatively, trade-offs between life stages might exist, where rapid larval growth rate may be negatively correlated with post-metamorphic locomotion, potentially due to energetic resource allocation trade-offs. In addition, other studies suggest that larval traits are decoupled from later life stages to allow for a transition in morphology and habitat. We tested how Bathygobius cocosensis hatch size, larval growth rates, settlement size and pelagic duration correlated with post-metamorphic thermal performance of burst swimming speed, routine metabolic rate and critical thermal maximum. We found that larval growth rate was negatively correlated with juvenile routine metabolic rate and burst swimming speed across a range of test temperatures. That is, fast-growing larvae had slower burst swimming speeds and lower routine metabolic rates across temperature as juveniles compared to slower-growing larvae. We also found that hatch size and pelagic larval duration were not correlated with post-metamorphic performance. Thus, we provide evidence both for larval traits having carry-over effects on later life stages and also for larval traits being decoupled with thermal performance post-metamorphosis. This is the first study to show that rapid larval growth rate is costly for post-metamorphic thermal performance.

Impact of fire and the recovery of molluscs in south‐east Australian salt marsh

SummaryFire has long been recognised as a natural force in structuring Northern Hemisphere salt marshes, yet little is known about the impact of fire on molluscs and native vegetation dynamics of Southern Hemisphere coastal salt marshes. Following a fire at Ash Island, Hunter River New South Wales, Australia in the summer 2012, we assessed patterns of recovery through time of gastropod populations and resident salt marsh vegetation including biomass for three keystone native plant species, Native Rush (Juncus kraussii Hochst.), a chenopod (Sarcocornia quinqueflora Bunge ex Ungen‐Sternberg A.J. Scott), Salt Couch (Sporobolus virginicus, L. Kunth) and the invasive Spiny Rush (Juncus acutus). In temperate east‐coast Australian salt marshes, Spiny Rush is displacing native salt marsh vegetation. After twelve months, the biomass of Native Rush recovered to similar pre‐burn levels. While fire affected the abundance, richness and composition of the gastropod assemblage differences were also largely driven by spatial variability. Gastropod assemblages associated with two of the higher elevation native species (Native Rush and Salt Couch) were impacted the most by fire. Greater abundance (between 1 and 5 orders of magnitude difference in abundance) and richness of gastropods were found in unburnt compared with burnt Native Rush and Salt Couch vegetation, while more gastropods were found in Spiny Rush in one site. Species prevalent in burnt vegetation included larger species of gastropods Ophicardelus ornatus (Ferussac, 1821) and Phallomedusa solida (Martens, 1878) with an unexpected spike in number of the smaller gastropod Tatea huonensis (Tenison‐Woods, 1876) in the spiny rush at one site only. In salt marsh habitats, many gastropods have planktonic larval dispersal stages which are dependent on the tidal height for transport and the structural complexity provided by vegetation at settlement. Since fire appears to negatively affect salt marsh gastropod populations within structurally complex Native Rush and Salt Couch, due consideration of the importance of these refuges for gastropods is recommended when fire or other disturbances occur in ecologically endangered salt marsh in the Southern Hemisphere. Managers need to consider spatial heterogeneity of molluscs and their recovery in the event of fire in Southern Hemisphere salt marshes.

Sensitivity of the Marine Calanoid Copepod Pseudodiaptomus pelagicus to Copper, Phenanthrene, and Ammonia.

There are limited acute toxicity test methods for native North American marine species that are considered zooplankton for their entire life cycle. Examples of standardized marine zooplankton methods include mussel, bivalve, and echinoderm development tests that use a relatively short-lived planktonic larval stage, chronic life-cycle toxicity tests using epibenthic copepods, and a 24-h Acartia tonsa copepod test method. The objectives of the present study were to: 1) develop and evaluate a novel, 48-h acute toxicity test method using the marine North American copepod Pseudodiaptomus pelagicus that is planktonic for its entire life cycle, and 2) determine the sensitivity of P. pelagicus relative to commonly tested marine toxicity test species. The average (±1 standard deviation) median lethal concentrations (LC50s) for copper (Cu), phenanthrene, and un-ionized ammonia were 32 ± 15 µg/L, 161 ± 51 µg/L, and 1.08 ± 0.30 mg NH3 /L, respectively. These results placed P. pelagicus on the more sensitive end of Cu and phenanthrene species sensitivity distributions. The copepod was less sensitive to un-ionized ammonia than commonly tested marine species. This finding suggests that the acute P. pelagicus test method will allow a focus on assessing the impacts of persistent contaminants of concern with less confounding impact from naturally occurring ammonia released to the water from sources such as suspended sediments. Environ Toxicol Chem 2019;38:1221-1230. Published 2019 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Deep segregation in the open ocean: Macaronesiaas an evolutionary hotspot for low dispersal marine invertebrates.

Diversification and speciation of terrestrial organisms are anticipated in oceanic islands such as Macaronesia, a group of Atlantic islands that have remained unconnected to continental landmasses. Hitherto, the diversification of marine organisms in oceanic islands, especially those with low vagility, has received little direct empirical analysis using molecular markers. Here, we focus on such a case study, through applying a multilocus molecular approach to investigate the diversity and evolution of a group that lacks a planktonic larval stage, the isopod genus Dynamene, in Macaronesia and Northeast Atlantic. Sequences of two mitochondrial (cytochrome c oxidase subunit I and 16SrRNA) and two nuclear (18SrRNA and 28SrRNA) loci were obtained from specimens of Dynamene edwardsi (Lucas, 1849), Dynamene magnitorata Holdich, 1968 and Dynamene bidentata (Adams, 1800) collected along the Northeast Atlantic and Macaronesia. Although no major phylogeographic structure was detected in D.bidentata and D.magnitorata, from five to nine deeply divergent lineages were evident within D.edwardsi. The divergent lineages displayed genetic distances comparable to those found among established species of peracarids. D.edwardsi exhibits a long, rich and complex phylogeographic history in Macaronesia, where the geodynamics of the islands possibly associated with founder effects and subsequent lack of gene flow among populations confounds patterns based on geographic proximity of targeted populations. Our findings collectively suggest a much larger role of oceanic islands in the diversification of marine invertebrates than previously anticipated. The work provides insights into the origins and dynamics of ongoing geographic segregation and associated deep divergence among sister evolutionary lineages in Macaronesia.

Active buoyancy adjustment increases dispersal potential in benthic marine animals.

While the study of dispersal and connectivity in the ocean typically centres on pelagic species and planktonic larval stages of benthic species, the present work explores an overlooked locomotor means in post‐settlement benthic stages that redefines their dispersal potential.Members of the echinoderm class Holothuroidea colonize a diversity of marine environments world‐wide, where they play key ecological and economical roles, making their conservation a priority. Holothuroids are commonly called sea cucumbers or sea slugs to reflect their slow movements and are assumed to disperse chiefly through pelagic larvae.The present study documents and explores their unexpected ability to actively modify their buoyancy, leading them to tumble or float at speeds orders of magnitudes faster than through benthic crawling. Two focal species representing different taxonomic orders, geographic distributions and reproductive strategies were studied over several years.Active buoyancy adjustment (ABA) was achieved through a rapid increase in water‐to‐flesh ratio by up to 740%, leading to bloating, and simultaneously detachment from the substrate. It occurred as early as 6 months post settlement in juveniles and was recorded in wild adult populations. In experimental trials, ABA was triggered by high conspecific density, decreasing salinity and increasing water turbidity. Based on field video footage, ABA‐assisted movements generated speeds of up to 90 km/day.These findings imply that displacement during planktonic larval stages may not supersede the locomotor capacity of benthic stages, challenging the notion of sedentarity. Combining the present results and anecdotal reports, ABA emerges as a generalized means of dispersal among benthic animals, with critical implications for world‐wide management and conservation of commercially and ecologically significant species.

Acquisition of obligate mutualist symbionts during the larval stage is not beneficial for a coral host.

Theory suggests that the direct transmission of beneficial endosymbionts (mutualists) from parents to offspring (vertical transmission) in animal hosts is advantageous and evolutionarily stable, yet many host species instead acquire their symbionts from the environment (horizontal acquisition). An outstanding question in marine biology is why some scleractinian corals do not provision their eggs and larvae with the endosymbiotic dinoflagellates that are necessary for a juvenile's ultimate survival. We tested whether the acquisition of photosynthetic endosymbionts (family Symbiodiniaceae) during the planktonic larval stage was advantageous, as is widely assumed, in the ecologically important and threatened Caribbean reef-building coral Orbicella faveolata. Following larval acquisition, similar changes occurred in host energetic lipid use and gene expression regardless of whether their symbionts were photosynthesizing, suggesting the symbionts did not provide the energetic benefit characteristic of the mutualism in adults. Larvae that acquired photosymbionts isolated from conspecific adults on their natal reef exhibited a reduction in swimming, which may interfere with their ability to find suitable settlement substrate, and also a decrease in survival. Larvae exposed to two cultured algal species did not exhibit differences in survival, but decreased their swimming activity in response to one species. We conclude that acquiring photosymbionts during the larval stage confers no advantages and can in fact be disadvantageous to this coral host. The timing of symbiont acquisition appears to be a critical component of a host's life history strategy and overall reproductive fitness, and this timing itself appears to be under selective pressure.

Metabarcoding on planktonic larval stages: an efficient approach for detecting and investigating life cycle dynamics of benthic aliens

Metabarcoding on planktonic larval stages: an efficient approach for detecting and investigating life cycle dynamics of benthic aliens

Creature from the Ria de Aveiro Lagoon. Did I just catch an alien species?

Event Abstract Back to Event Creature from the Ria de Aveiro Lagoon. Did I just catch an alien species? Francisco R. Maia1* 1 Portuguese Institute of Ocean and Atmosphere (IPMA), Portugal The present communication reports the occurrence of the alien soft-shell clam Mya arenaria (Linnaeus, 1758) in the Ria de Aveiro lagoon (NW Portugal). A total of 47 living specimens were collected in spring 2013 (April) and winter 2019 (January) in an intertidal mudflat located at the upstream end of Mira channel (400 32’ 23 N; 80 45’ 56 W). In this area, the soft-shell clam was able to maintain a well-established population in close coexistence with another endobenthic bivalve species, the native clam Scrobicularia plana. The soft-shell clam Mya arenaria is native to the Atlantic coasts of North America and its probably the first marine invasive species recorded in European waters. Presumably, it was introduced in the North Sea by the Vikings in the 13th century (Peterson et al., 1992), from which it spread throughout its current distribution. At present, it is commonly found along the coasts of the North and the Baltic Seas, northern Adriatic Sea, the Black Sea, on all British and Irish coasts, France, Spain, Portugal and in the Mediterranean Sea. The ability to survive in a wide range of habitats; the capacity to tolerate a broad set of environmental conditions at all life stages; the high fecundity levels; and the long-lived planktonic larval stage, have been proposed to explain the long-distance dispersal of this species and its success as an invader. To our knowledge, there isn’t any scientific evidence reporting negative effects of Mya arenaria on Ria de Aveiro ecosystems. Nevertheless, some authors refer that this species has the capacity to change the surrounding environment through its burrowing, feeding and excretory activities, and it is capable to outcompete native bivalve species for space and food, reducing diversity, distribution and abundance of those species. For this reason, more research is needed to better evaluate and fully understand the long-term impacts of Mya arenaria on the native bivalve assemblages of Ria de Aveiro lagoon. References Petersen K.S., Rasmussen, K.L., Heinemeier, J., and Rud, N. (1992). Clams before Columbus? Nature, 359:679 Keywords: Mya arenaria, soft-shell clam, alien species, Invasions, Ria de Aveiro lagoon, Portugal Conference: XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019. Presentation Type: Poster Presentation Topic: Global Change, Invasive Species and Conservation Citation: Maia FR (2019). Creature from the Ria de Aveiro Lagoon. Did I just catch an alien species?. Front. Mar. Sci. Conference Abstract: XX Iberian Symposium on Marine Biology Studies (SIEBM XX) . doi: 10.3389/conf.fmars.2019.08.00039 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 06 Apr 2019; Published Online: 27 Sep 2019. * Correspondence: Dr. Francisco R Maia, Portuguese Institute of Ocean and Atmosphere (IPMA), Lisbon, Portugal, maia.francisco@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Francisco R Maia Google Francisco R Maia Google Scholar Francisco R Maia PubMed Francisco R Maia Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Lethal and sublethal impacts of a micropredator on post-settlement Caribbean reef fishes.

The transition from a planktonic larval stage to a benthic or demersal juvenile stage, "recruitment", is a crucial event in the life history of coral reef fishes, and has a strong influence on population size. Predation by piscivorous fishes is thought to be the main determinant of recruitment success, and has received the most attention. However, recent studies suggest that recently settled reef fishes are also an important target of micropredation from blood-feeding ectoparasites which may have significant lethal and sublethal effects. In this study, we quantified the relationship between levels of infestation by gnathiid isopods and mortality rates among juveniles of three species of reef fishes as a function of body mass both within and among species. We found that a single gnathiid isopod larva could kill fish of all three species shortly after settlement, up to 0.116g [18mm fork length (FL)] in French grunt (Haemulon flavolineatum), 0.027g (15mm FL) in masked goby (Coryphopterus personatus) and 0.01g (9mm FL) in beaugregory damselfish (Stegastes leucostictus). For juvenile S. leucostictus, we also compared the ability of fish to defend a territory when infested with a sublethal number of gnathiids versus uninfected individuals. Uninfected fish were significantly more likely to win-pairwise contests versus infected fish. These findings suggest that gnathiids can significantly impact juvenile coral reef fish survival, and affect population dynamics well past the settlement stage.

A Griesbachian (Early Triassic) Mollusc Fauna from the Sidazhai Section, Southwest China, with Paleoecological Insights on the Proliferation of Genus Claraia (Bivalvia)

After the end-Permian mass extinction, genus Claraia (Bivalvia) was the most abundant and most noticeable fossil during the survival and recovery stage. However, the reasons for the proliferation of Claraia are still debated. This paper describes a new Griesbachian (Early Triassic) mollusc fauna from deep-water settings in South China in the aftermath of end-Permian mass extinction. This fauna yielded five bivalve species in two genera (Claraia griesbachi, C. wangi, C. stachei, C. radialis, and Promyalina putiatinensis) and two ammonoid species (Ophiceras sp. and Ussuridiscus sp.) and could be assigned to the Claraia wangi-C. griesbachi assemblage zone, indicating a Middle-Late Griesbachian Age. The bivalves were dominated by Claraia griesbachi and were featured by articulated Claraia fossils. As Claraia was epibyssate, it was an excellent autochthonous fauna. While the shallow and deep marine water became dysoxic to anoxic globally, as indicated by recent studies of the early Early Triassic, we suggest the genus Claraia could tolerate dysoxic and/or anoxic conditions and its proliferation could be attributed to its physiological features which were adapted to the stressed environment. The wide distribution of Claraia was probably related to its planktonic larval stage. Where the larva of Claraia could have been transported by ocean flow and increased its potential for long-distance dispersal. In addition, Claraia was a significant disaster and opportunistic taxon during the Early Triassic based on observations in South China.

Pelagic larval dispersal habits influence the population genetic structure of clam Gomphina aequilatera in China.

Pelagic larval dispersal habits influence the population genetic structure of marine mollusk organisms via gene flow. The genetic information of the clam Gomphina aequilatera (short larval stage, 10 days) which is ecologically and economically important in the China coast is unknown. To determine the influence of planktonic larval duration on the genetic structure of G. aequilatera. Mitochondrial markers, cytochrome oxidase subunit i (COI) and 12S ribosomal RNA (12S rRNA), were used to investigate the population structure of wild G. aequilatera specimens from four China Sea coastal locations (Zhoushan, Nanji Island, Zhangpu and Beihai). Partial COI (685bp) and 12S rRNA (350bp) sequences were determined. High level and significant FST values were obtained among the different localities, based on either COI (FST = 0.100-0.444, P < 0.05) or 12S rRNA (FST = 0.193-0.742, P < 0.05), indicating a high degree of genetic differentiation among the populations. The pairwise Nm between Beihai and Zhoushan for COI was 0.626 and the other four pairwise Nm values were > 1, indicating extensive gene flow among them. The 12S rRNA showed the same pattern. AMOVA test results for COI and 12S rRNA indicated major genetic variation within the populations: 77.96% within and 22.04% among the populations for COI, 55.73% within and 44.27% among the populations for 12S rRNA. A median-joining network suggested obvious genetic differentiation between the Zhoushan and Beihai populations. This study revealed the extant population genetic structure of G. aequilatera and showed a strong population structure in a species with a short planktonic larval stage.

Genetic diversity and population connectivity of the sea urchin Tripneustes gratilla along the South African coast

The collector sea urchin Tripneustes gratilla has been identified as a species with potential for aquaculture production in South Africa. The species’ roe is considered a culinary delicacy in Asia and Europe. However, T. gratilla remains genetically uncharacterised in South Africa. Therefore, the purpose of this study was to provide baseline genetic information consisting of estimates of genetic diversity and population stratification, which may aid in future sustainable use of this urchin resource. A total of 22 species-specific microsatellite markers were used for the genetic characterisation of T. gratilla samples from along the South African coast, at Haga Haga, Coffee Bay, Hibberdene, Ballito Bay and Sodwana Bay. A moderate level of genetic diversity was observed, with an average number of alleles of 7.89 and an average effective number of alleles of 6.57, as well as an average observed heterozygosity of 0.55. Population differentiation tests suggest that the geographically representative samples form part of a single, large interbreeding population, with a global Fst estimate of 0.02 (p > 0.05). This finding is likely explained by high levels of gene flow between these locations caused by extensive larval dispersal during the planktonic larval stage. The panmixia observed within these natural populations of T. gratilla indicate that they could be managed as a single genetic stock.

The little shrimp that could: phylogeography of the circumtropical Stenopus hispidus (Crustacea: Decapoda), reveals divergent Atlantic and Pacific lineages.

The banded coral shrimp, Stenopus hispidus (Crustacea: Decapoda: Stenopodidea) is a popular marine ornamental species with a circumtropical distribution. The planktonic larval stage lasts ∼120–253 days, indicating considerable dispersal potential, but few studies have investigated genetic connectivity on a global scale in marine invertebrates. To resolve patterns of divergence and phylogeography of S. hispidus, we surveyed 525 bp of mitochondrial cytochrome c oxidase subunit I (COI) from 198 individuals sampled at 10 locations across ∼27,000 km of the species range. Phylogenetic analyses reveal that S. hispidus has a Western Atlantic lineage and a widely distributed Indo-Pacific lineage, separated by sequence divergence of 2.1%. Genetic diversity is much higher in the Western Atlantic (h = 0.929; π = 0.004) relative to the Indo-Pacific (h = 0.105; π < 0.001), and coalescent analyses indicate that the Indo-Pacific population expanded more recently (95% HPD (highest posterior density) = 60,000–400,000 yr) than the Western Atlantic population (95% HPD = 300,000–760,000 yr). Divergence of the Western Atlantic and Pacific lineages is estimated at 710,000–1.8 million years ago, which does not readily align with commonly implicated colonization events between the ocean basins. The estimated age of populations contradicts the prevailing dispersal route for tropical marine biodiversity (Indo-Pacific to Atlantic) with the oldest and most diverse population in the Atlantic, and a recent population expansion with a single common haplotype shared throughout the vast Indian and Pacific oceans. In contrast to the circumtropical fishes, this diminutive reef shrimp challenges our understanding of conventional dispersal capabilities of marine species.

Planktonic bivalve larvae identification and quantification in Gomso Bay, South Korea, using next-generation sequencing analysis and microscopic observations

Planktonic larval stages of bivalves are notoriously difficult to identify due to their similar morphology. To evaluate changed patterns in the presented planktonic bivalve larvae within Gomso Bay (Yellow Sea, South Korea), three sites were sampled twice a month from June to October 2015 and were analysed using next-generation sequencing (NGS) and light microscopy. Bivalve larvae revealed different patterns, and at least five bivalve taxa were only detected by the NGS. According to the NGS results, most bivalve larvae were Crassostrea gigas (37%), followed by Ruditapes philippinarum (26%), and Solen strictus (23%); Mactra chinensis and M. veneriformis accounted for <1% of the bivalve larvae. C. gigas and S. strictus were most abundant in late June, but rare in the other investigated periods, while R. philippinarum was more abundant in June and late September. Microscopic observations showed a similar trend to the NGS in terms of bivalve larvae presence, although they were difficult to identify the exact species. Thus, morphological and molecular approaches should be combined in future studies to provide accurate sequences of correctly identified specimens to develop NGS libraries.

Association between the planktonic larval and benthic stages of Manila clam Ruditapes philippinarum in eastern Hokkaido, Japan

The association between planktonic larval and benthic stages of Manila clam Ruditapes philippinarum and factors determining successful recruitment were studied in Akkeshi-ko estuary and Akkeshi Bay, Hokkaido, northern Japan. The field study showed that planktonic larvae were localized mainly in the bay after dispersal from the estuary and recruitment to the estuarine fishing grounds was not always successful. A numerical analysis suggested that estuarine circulation transported tracers, used to simulate planktonic larva, from the estuary to the bay but the number of returning tracers varied depending on the river discharge and wind direction. The planktonic larvae were affected by unsuitable conditions for survival in the estuary, such as high turbidity. We conclude that most larvae develop within the bay, where conditions are more saline and less turbid, and that although return to the estuary is essential for recruitment, it is not necessarily related to the abundance of larvae.

Duplicated FoxA genes in the leech Helobdella: Insights into the evolution of direct development in clitellate annelids

As an adaptation to the land, the clitellate annelid had reorganized its embryogenesis to develop "directly" without the ancestral planktonic larval stage. To study the evolution of gut development in the directly developing clitellates, we characterized the expression pattern of the conserved gut gene, FoxA, in the embryonic development of the leech. The leech has three FoxA paralogs. Hau-FoxA1 is first expressed in a subset of endoderm cells and then in the foregut and the midgut. Hau-FoxA2 is expressed in the stomodeum, which is secondarily derived from the anterior ectoderm in the clitellates rather than the tissue around the blastopore, the ancestral site of mouth formation in Phylum Annelida. Hau-FoxA3 is expressed during the morphogenesis of segmental ganglia from the ectodermal teloblast lineages, a clitellate-specific trait. Hau-FoxA1 and Hau-FoxA2 are also expressed during the morphogenesis of the leech-specific front sucker. The expression patterns suggested that Hau-FoxA1 carries out most of the conserved function in the endoderm and gut development, while the other two duplicates appear to have evolved unique novel functions in the directly developing clitellate embryos. Therefore, neofunctionalization and co-option of FoxA might have made a significant contribution to the evolution of direct development in Clitellata. Developmental Dynamics 247:763-778, 2018. © 2018 Wiley Periodicals, Inc.

Early development and growth of a selective line of Argopecten irradians concentricus

PDF HTML阅读 XML下载 导出引用 引用提醒 墨西哥湾扇贝选育系早期发育与生长 DOI: 作者: 作者单位: 广西大学 动物科学技术学院, 广西 南宁 530004 作者简介: 封杰(1991-),男,硕士研究生,主要从事海洋贝类遗传育种与繁育研究.E-mail:dzfjdyx@163.com 通讯作者: 中图分类号: S968 基金项目: 广西科学研究与技术开发计划项目（桂科攻14121006-2-5）. Early development and growth of a selective line of Argopecten irradians concentricus Author: Affiliation: College of Animal Science and Technology, Guangxi University, Nanning 530004, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在水温28~29℃、盐度24~25条件下，研究墨西哥湾扇贝（）选育系的早期发育及幼虫和稚贝的生长。受精卵经50 min发育至卵裂，经22~24 h发育至D形幼虫，经11 d发育至眼点幼虫并出现足，进入附着变态阶段。选育系的胚胎发育时间和浮游幼虫前期壳长、壳高与对照系比较差异不显著（<0.05）。选育系的附着变态率和存活率与对照系比较均差异显著（<0.05），且优势明显。本研究表明，墨西哥湾扇贝浮游幼虫发育前期缓慢，幼虫后期、稚贝期生长迅速；壳长和壳高的生长速度不同步，幼虫前期壳长生长快于壳高，后期壳高生长快于壳长，并于第28~30天时壳高超过壳长。墨西哥湾扇贝选育系在幼虫和稚贝阶段生长速度明显快于对照系，具有明显的生长优势及生长潜力。 Abstract:Development of embryos, larvae, and juveniles of were observed using an optical microscope, with a digital camera at water temperatures of 28℃ to 29℃ and salinity of 24 to 25. Zygotes began the first cleavage at 50 min post-fertilization, developed to D-shaped larvae between 22 and 24 h, and the larvae developed eye points and feet at day 11 and entered the attachment metamorphosis stage. There was no significant difference in the time of embryo development between the selective and control lines (>0.05). The shell length and shell height were not significantly different at the embryonic and early larval stages between the selective and control lines (>0.05), but there was a significant difference in shell length and shell height at the post-larval and attachment metamorphosis stages between the selective and control lines (<0.05). The metamorphosis and survival rates of the selective line were significantly different from those of the control line (<0.05), and the selective line has obvious advantages. The results show that the growth of the early planktonic larval stage of was slow but at the post-larval and juvenile stages, it was rapid. The growth of shell length and shell height of was not synchronized. The growth speed of shell length exceeded that of shell height at the earlier larval stage, and at the later larval stage, the growth speed of shell height exceeded that of shell length; at 28 to 30 days, shell height exceeded shell length. At the larval and juvenile stages, the growth of the selective line significantly exceeded that of the control line. The selective line has obvious growth advantages and growth potential. 参考文献 相似文献 引证文献

Spatial variation in life history characteristics of waved whelk (Buccinum undatum L.) on the U.S. Mid-Atlantic continental shelf

Abstract Recent expansion of the unmanaged waved whelk (Buccinum undatum) fishery within the United States Mid-Atlantic continental shelf region has prompted investigation into local life history parameters. Limited adult dispersal and lack of a planktonic larval stage has the potential to create spatially distinct populations with respect to size of sexual maturity and size frequency. During the summer of 2015, a comprehensive survey was undertaken to evaluate population structure, sex ratio, relative abundance, and size of sexual maturity for whelk in the Mid-Atlantic. Samples (n = 228) were collected from Georges Bank through the DelMarVa region using a modified scallop dredge at depths ranging from 27.4 to 112 m, with most whelk caught between 40–75 m, and peak abundances at 51–60 m. All whelk collected (n = 3877) were sexed, weighed, measured, and assessed for maturity. Sex ratios were skewed in favor of females in the south and balanced through the rest of the regions. Size of maturity ranged from approximately 56–73 mm and varied among regions and sex. Estimates of size of sexual maturity for B. undatum from other regions of the world were compiled, demonstrating that the size of maturity for this species is highly variable, and current minimum landing size regulations tend to fall below the estimated size of sexual maturity, potentially increasing the risk of recruitment overfishing. Overall, spatial variation in whelk phenotype suggests local adaptation in this species, indicating that regional management would be most appropriate.