Life Stages Of Marine Invertebrates Research Articles

Acute heat priming promotes short-term climate resilience of early life stages in a model sea anemone

Across diverse taxa, sublethal exposure to abiotic stressors early in life can lead to benefits such as increased stress tolerance upon repeat exposure. This phenomenon, known as hormetic priming, is largely unexplored in early life stages of marine invertebrates, which are increasingly threatened by anthropogenic climate change. To investigate this phenomenon, larvae of the sea anemone and model marine invertebrate Nematostella vectensis were exposed to control (18 °C) or elevated (24 °C, 30 °C, 35 °C, or 39 °C) temperatures for 1 h at 3 days post-fertilization (DPF), followed by return to control temperatures (18 °C). The animals were then assessed for growth, development, metabolic rates, and heat tolerance at 4, 7, and 11 DPF. Priming at intermediately elevated temperatures (24 °C, 30 °C, or 35 °C) augmented growth and development compared to controls or priming at 39 °C. Indeed, priming at 39 °C hampered developmental progression, with around 40% of larvae still in the planula stage at 11 DPF, in contrast to 0% for all other groups. Total protein content, a proxy for biomass, and respiration rates were not significantly affected by priming, suggesting metabolic resilience. Heat tolerance was quantified with acute heat stress exposures, and was significantly higher for animals primed at intermediate temperatures (24 °C, 30 °C, or 35 °C) compared to controls or those primed at 39 °C at all time points. To investigate a possible molecular mechanism for the observed changes in heat tolerance, the expression of heat shock protein 70 (HSP70) was quantified at 11 DPF. Expression of HSP70 significantly increased with increasing priming temperature, with the presence of a doublet band for larvae primed at 39 °C, suggesting persistent negative effects of priming on protein homeostasis. Interestingly, primed larvae in a second cohort cultured to 6 weeks post-fertilization continued to display hormetic growth responses, whereas benefits for heat tolerance were lost; in contrast, negative effects of short-term exposure to extreme heat stress (39 °C) persisted. These results demonstrate that some dose-dependent effects of priming waned over time while others persisted, resulting in heterogeneity in organismal performance across ontogeny following priming. Overall, these findings suggest that heat priming may augment the climate resilience of marine invertebrate early life stages via the modulation of key developmental and physiological phenotypes, while also affirming the need to limit further anthropogenic ocean warming.

Diffusive Boundary Layers and Ocean Acidification: Implications for Sea Urchin Settlement and Growth

Chemical changes in the diffusive boundary layer (DBL) generated by photosynthesising macroalgae are expected to play an important role in modulating the effects of ocean acidification (OA) but little is known about the effects on early life stages of marine invertebrates. Larvae that settle to macroalgal surfaces and remain within the DBL will experience pH conditions markedly different from the bulk seawater. We investigated the interactive effects of seawater pH and DBL thickness on settlement and early post-settlement growth of the sea urchin Pseudechinus huttoni, testing whether coralline-algal DBLs act as an environmental buffer to OA. DBL thickness and pH(T) levels above the crustose coralline algal surfaces varied with light availability (with photosynthesis increasing pH to as high as pH 9.0 and respiration reducing pH to as low as pH 7.4 under light and dark conditions respectively), independent of bulk seawater pH (7.5, 7.7 and 8.1). Settlement success of P. huttoni increased over time for all treatments, irrespective of estimated pH in the DBL. Juvenile test growth was similar in all DBL manipulations, showing resilience to variable and low seawater pH. Spine development, however, displayed greater variance with spine growth being negatively affected by reduced seawater pH in the DBL only in the dark treatments. Scanning electron microscopy revealed no observable differences in structural integrity or morphology of the sea urchin spines among pH treatments. Our results suggest that early juvenile stages of Pseudechinus huttoni are well adapted to variable pH regimes in the DBL of macroalgae across a range of bulk seawater pH treatments.

The effect of temperature on physiology, toxicity and toxin content of the benthic dinoflagellate Coolia malayensis from a seasonal tropical region

Coolia malayensis is one of the commonly found benthic dinoflagellates in Hong Kong which can produce biotoxins and threaten the early life stages of marine invertebrates. Seawater temperature has been recognized as one of the primary environmental factors that affect the formation of harmful algal blooms. The present study evaluated the responses of C. malayensis, including growth, toxicity and toxin content (putative analogues of okadaic acid and azaspiracids), after exposure to a range of seven different temperatures (i.e., 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, and 28°C). The highest algal density and specific growth rate were recorded at 24°C. Significantly higher Fv/Fm (maximum quantum yield of PSII) and total phaeo-pigment values were observed in the exponential growth phase at 28°C. The toxicity of the algal extract, which was assessed by the lethality rate of Artemia larvae, increased with temperature. The highest toxin content was detected at the second highest temperature treatment, i.e., 26°C. Overall, temperature had significant effects on the physiological activities and toxicity of C. malayensis. This study has raised attention to the potentially increasing risks posed by toxic benthic dinoflagellates during heat waves in coastal waters.

Effects of temperature on early development of the New Zealand geoduckPanopea zelandica(Quoy & Gaimard, 1835)

Ambient seawater temperature is an important factor during the early life stages of marine invertebrates. Temperature is often manipulated in hatcheries to shorten the incubation period before the larval rearing phase. In this study, the effect of temperature on the early development of the geoduck Panopea zelandica was investigated over a 48-hr period to identify the optimum temperature for fertilization and development in a controlled environment. Eggs and sperm collected from broodstock were exposed to ten temperatures ranging between 11.8 and 23.7°C, and fertilization and subsequent development were monitored over 48 hr. Highest percentages of fertilization were achieved at 23.7°C, which was the highest temperature tested in this study. However, the development of P. zelandica embryos was greatly hindered at temperatures >18.5°C due to a range of abnormalities arising from uneven cell division and cellular blebbing. All larvae died at the highest temperature of 23.7°C within 48 hr of exposure. The combined fertilization success and embryo development data indicate that 18.5°C is the optimal temperature for incubating P. zelandica embryos under hatchery conditions.

The weakest link: sensitivity to climate extremes across life stages of marine invertebrates

Predicting the effects of climate change on Earth's biota becomes even more challenging when acknowledging that most species have life cycles consisting of multiple stages, each of which may respond differently to extreme environmental conditions. There is currently no clear consensus regarding which stages are most susceptible to increasing environmental stress, or ‘climate extremes’. We used a meta‐analytic approach to quantify variation in responses to environmental stress across multiple life stages of marine invertebrates. We identified 287 experiments in 29 papers which examined the lethal thresholds of multiple life stages (embryo, larva, juvenile and adult) of both holoplanktonic and meroplanktonic marine invertebrates subjected to the same experimental conditions of warming, acidification and hypoxia stress. Most studies considered short acute exposure to stressors. We calculated effect sizes (log response ratio) for each life stage (unpaired analysis) and the difference in effect sizes between stages of each species (paired analysis) included in each experiment. In the unpaired analysis, all significant responses were negative, indicating that warming, acidification and hypoxia tended to increase mortality. Furthermore, embryos, larvae and juveniles were more negatively affected by warming than adults. The paired analysis revealed that, when subjected to the same experimental conditions, younger life stages were more negatively affected by warming than older life stages, specifically among pairings of adults versus juveniles and larvae versus embryos. Although responses to warming are well documented, few studies of the effects of acidification and hypoxia met the criteria for inclusion in our analyses. Our results suggest that while most life stages will be negatively affected by climate change, younger stages of marine invertebrates are more sensitive to extreme heating events.

Adverse effects of the SSRI antidepressant sertraline on early life stages of marine invertebrates

Widespread contamination of coastal environments by emerging compounds includes low concentrations of pharmaceuticals. These pollutants are not currently incorporated in monitoring programs despite their effects on non-target organisms are very little documented. Among the selective serotonin reuptake inhibitor (SSRI) antidepressants, sertraline (SRT) is one of the most prescribed globally. In this work, earlier life stages of Amphibalanus amphitrite, Brachionus plicatilis and Mytilus galloprovincialis were exposed to environmental concentrations of SRT in order to study both sub-lethal and lethal responses in 24/48 h-tests. Low concentrations of SRT altered significantly swimming behavior in A. amphitrite and B. plicatilis giving 48 h-EC50 (μg/L) of 113.88 and 282.23, respectively whereas higher values were observed for mortality and immobilization. EC50 embryotoxicity with M. galloprovincialis was 206.80 μg/L. This work add new data about SRT ecotoxicity on marine invertebrates and confirms the applicability of behavioral endpoints to evaluate the environmental impact of antidepressants in marine organisms.

The effect of mesoscale oceanographic features on the distribution of mussel larvae along the south coast of South Africa

The coupling of benthic and pelagic life stages of marine invertebrates is central to understanding their population dynamics and is influenced by hydrodynamic processes at multiple spatial scales. Here we provide a regional scale study that identifies mesoscale oceanographic features linked to the distribution of mussel larvae. We surveyed the distribution of mussel larvae along 12 shelf to slope transects within an alongshore distance of about 700km along the Agulhas Bank off South Africa. Oceanographic and larval abundance data were collected simultaneously to determine how larval distribution is related to physical factors. Larval abundances were most closely correlated with temperature, salinity, beam attenuation (which indicates particle concentrations), and zonal (east–west) water velocity. In most regions, the highest larval concentrations were observed within an average distance of 3.7km from the coastline. Three mesoscale oceanographic mechanisms were identified that could explain larval distribution on separate parts of the coast. These were: a solitary meander whose leading end advects the Agulhas Current onto the continental shelf as an Agulhas Current Meander and whose lagging end advects the Agulhas Current offshore as a Natal Pulse, and the accumulation of larvae in a region with known internal wave activity. The Agulhas Current Meander swept large numbers of recently “spawned” larvae up to 30km offshore, acting as a corridor for larval loss, or a population sink. Onshore retention seems, however, to be generally characteristic of this region, when the Agulhas Current is not on the continental shelf. This study highlights how mesoscale features are associated with larval density, transport, and coupling between the pelagic and benthic systems of the Agulhas Bank.

Temperature limits to early development of the New Zealand sea urchin Evechinus chloroticus (Valenciennes, 1846)

Seawater temperature is an important environmental factor for the early life stages of marine invertebrates. In this study we evaluated and described the effects of temperature during early development of E. chloroticus, identifying the optimum temperature range and upper thermal limit for successful development. The temperature range evaluated was between 15–24°C which included the normal seawater temperatures during the spawning season in northern New Zealand, as well as the highest temperature projected by the IPCC for this region due to global warming (1–3°C by the year 2100). Gametes from several females and males were used in the experiment. Fertilization was carried out at different temperatures and development was monitored at different time points after fertilization in each temperature. The development rate of E. chloroticus increased with an increase in seawater temperature. However, at temperatures higher than 21.5°C the amount of abnormal development reached ∼30%. The optimum temperature for early development was between 15–21°C, whereas the upper thermal limit was ∼24°C. Therefore, early development of E. chloroticus is negatively affected by an increase in seawater temperature of ∼3–4°C above current seawater temperature levels in northern New Zealand. The thermal sensitivity of early life stages of E. chloroticus could affect survival rates during early development of this species in a global warming scenario, which could impair recruitment in populations which are exposed to higher temperatures, leading to possible distributional shifts of this species.

About the Cover.

Next article FreeAbout the CoverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreCover“Biology of Marine Invertebrate Larvae,” the “virtual symposium” in this issue, offers a glimpse of the broad extent of current research on early life stages of marine invertebrates. The images on the cover are a small sample of some of the early developmental stages and larvae that are considered in research, review, and position papers presented in this issue. All stages are about 1 millimeter, or less, in size. Clockwise from top: the large and yolky egg of the sea star Nepanthia troughtoni; a zoea larva of a crab in the family Cancridae; a feeding, late-stage pluteus larva of the sea urchin Tripneustes gratilla; a nonfeeding brachiolaria larva of a sea star collected with a plankton net; a feeding veliger larva of a gastropod in the Thaidae, a family of carnivorous snails; and a nonfeeding, coronate larva of a colonial “moss animal” in the bryozoan genus Bugula. The central image is a confocal z-projection of a phallacidin-labeled planktonic planuliform larva of the nemertean worm Paranemertes peregrina.Larvae occur between the embryonic and juvenile stages of most marine invertebrates. They are small (on the order of 1 mm), slow moving, and usually found suspended in the water where they are dispersed by currents. As individuals they exhibit behavior: they swim, (often) feed, respond to many environmental stimuli, and eventually settle and metamorphose to become juveniles. Larvae are studied for many reasons, including their unusual anatomy and behavior (compared to that of adults), their dynamic development as they change from embryos to juveniles, their dispersal which links populations genetically, and their recruitment as they contribute new individuals to local populations and influence population dynamics. Larval forms and variations among them have also been foci in considerations of animal evolution and animal ecology, and more recently, of how developmental mechanisms and evolutionary forces interact to create the diversity of organisms found among invertebrate phyla. Photo credits: Confocal image of the planuliform larva of Paranemertes peregrina, Svetlana Maslakova (University of Oregon). All other cover images, Richard Emlet (University of Oregon). Cover design: Beth Liles (Marine Biological Laboratory). Next article DetailsFiguresReferencesCited by The Biological Bulletin Volume 216, Number 3June 2009 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/BBLv216n3cover Views: 43 © 2009 by Marine Biological Laboratory. All rights reserved.PDF download Crossref reports no articles citing this article.

Chemical defense of early life stages of benthic marine invertebrates.

Accurate knowledge of factors affecting the survival of early life stages of marine invertebrates is critically important for understanding their population dynamics and the evolution of their diverse reproductive and life-history characteristics. Chemical defense is an important determinant of survival for adult stages of many sessile benthic invertebrates, yet relatively little consideration has been given to chemical defenses at the early life stages. This review examines the taxonomic breadth of early life-stage chemical defense in relation to various life-history and reproductive characteristics, as well as possible constraints on the expression of chemical defense at certain life stages. Data on the localization of defensive secondary metabolites in larvae and the fitness-related consequences of consuming even a small amount of toxic secondary metabolites underpin proposals regarding the potential for Müllerian and Batesian mimicry to occur among marine larvae. The involvement of microbial symbionts in the chemical defense of early life stages illustrates its complexity for some species. As our knowledge of chemical defenses in early life stages grows, we will be able to more rigorously examine connections among phylogeny, chemical defenses, and the evolution of reproductive and life-history characteristics among marine invertebrates.