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In order to test the systematic position of archaeocyaths, a group of Cambrian, exclusively marine fossils of unclear biological affinity, currently ascribed mostly to sponges (Porifera), we present an alternative explanation supporting the early idea of siphonous green algal affinity of archaeocyaths. The new arguments are based on a study of the morphology, microstructure, and microtaphonomy of early Cambrian (Tommotian and Atdabanian) archaeocyathan specimens from northeastern Siberia. Light microscopic and scanning electron microscopic (SEM) observations revealed that in many specimens the outer, often microlaminated, skeletal fabric grades continuously into the microfabric similar to that of microbial bush-like and dendritic microfossils such as Angulocellularia and Renalcis. The polyhedral to subglobular units characterizing the skeletal microfabric of the studied archaeocyaths and their microbial outgrowths are most similar to recent and fossil mineralized (calcified) colonies of benthic coccoidal cyanobacteria. This means that what had heretofore been interpreted as skeletons secreted by archaeocyathan organisms represent calcareous crusts precipitated by epibiontic cyanobacteria-like microbes, probably associated with a variety of other bacteria, colonizing surfaces and internal spaces of soft-bodied archaeocyathan organisms. Our study shows that a number of the morphological traits of archaeocyaths conserved by the mineralized microbial cover are similar to those of of modern siphonous green algae, like the marine genus Codium Stackhouse (Bryopsidales). Identifiable in well-preserved archaeocyaths are remains of such traits characteristic for Codium species as utricles, medullary threads, juvenile stages (primordia), and coalescence structures. The taxonomic and palaeoenvironmental implications of the recognition of archaeocyaths as possible consortia of siphonous green seaweeds (Chlorophyta) and cyanobacteria-like microbes are briefly discussed.

The critical size hypothesis states that pelagic larvae (vertebrate or invertebrate) must reach a critical size to begin metamorphosis and settle to their suitable reef habitat; however, there have been few critical tests of its broader validity. If there were a narrower range of ages at settlement relative to size, then the data would conform to a critical age hypothesis. It would also be predicted that size or age would be truncated respectively at the lower limit for each hypothesis. These hypotheses were tested for 2 species of coral reef fish from the Great Barrier Reef. Variation in age at settlement forPomacentrus coelestiswas greater than that of size at settlement for fish collected in waters of different temperatures, and the size distribution was truncated at a size of ~9.3 mm; accordingly, we accepted the critical size at settlement hypothesis for this species. In contrast,Scolopsis bilineatusmet one criterion to reject the critical size hypothesis, based on variation, but truncation in size was found. Variation in age aligned with a critical age at settlement hypothesis. There was a variable relationship between age at settlement and size for both species. Strong evidence is provided that growing fast in the plankton and settling quickly may be advantageous for fish. For both species, settlers with a short planktonic larval duration, and sometimes small size at settlement, had grown faster in the plankton and may have experienced better conditions. Differences in pre-settlement growth are likely to affect the maximum size at which fish can settle and post-settlement survivorship.

Freshwater-dominated estuaries experience large fluctuations in their physical and chemical environments which may influence larval dispersal, settlement, and connectivity of populations with pelagic larval stages. We used settlement patterns and natural tagging along with numerical hydrodynamic model results to assess settlement and connectivity among oysters across the freshwater-dominated Mobile Bay-eastern Mississippi Sound (MB-EMS) system. Specifically, we (1) tested how freshwater inputs and associated environmental attributes influenced settlement patterns during high and low discharge conditions in 2014 and 2016, respectively, and (2) analyzed trace element (TE) ratios incorporated into multiple shell types (larval and settled shell of spat and adult shells) to determine if shells collected in situ incorporate temporally stable site-specific signatures. We also assessed if TE ratios compared between adult (TE natal signature proxy) and larval shells could infer connectivity. Larval settlement was 4× higher during low discharge than during high discharge when oyster larvae only settled in higher salinity regions (EMS). Spat and adult shells incorporated site-specific TE ratios that varied from weeks to months. Connectivity results (May-June 2016 only) suggest that EMS is an important larval source to EMS and lower MB. While we were able to infer probable connectivity patterns using adult and larval shells, more study is needed to assess the utility of adult shells as proxies for natal-location TE signatures. Results provide a baseline for measuring future larval connectivity and adult distribution changes in the MB-EMS system. Biological and geochemical data demonstrate the potential to identify environmental attributes that spatiotemporally mediate settlement and connectivity in dynamic systems.

Deep-sea Cibicidoides pachyderma (forma mundulus) and related Cibicidoides spp. were cultured at in situ pressure for 1–2 d, or 6 weeks to 3 months. During that period, fluorescence analyses following BCECF-AM (2′,7′-bis(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester) or calcein (bis[N,N-bis(carboxymethyl)aminomethyl]-fluorescein) labelling revealed a persisting cytoplasmic sheet or envelope surrounding the Cibicidoides tests. Thus, the Cibicidoides shell can be considered as an internal rather than an external cell structure. A couple of days to a week after being transferred into high-pressure aquaria and adjusted to a pressure of 115 bar, the foraminifera changed from a mobile to a more or less sessile living mode. During this quasi-sessile way of life, a series of comparably thick static ectoplasmic structures developed that were not resorbed or remodelled but, except for occasional further growth, remained unchanged throughout the experiments. Three different types of these permanent structures were observed. (a) Ectoplasmic “roots” were common in adult C. pachyderma, C. lobatulus, and C. wuellerstorfi specimens. In our experiments single ectoplasmic roots grew to a maximum of 700 times the individuals' shell diameter and were presumably used to anchor the specimen in an environment with strong currents. (b) Ectoplasmic “trees” describe rigid ectoplasmic structures directed into the aquarium's water body and were used by the foraminifera to climb up and down these ectoplasmic structures. Ectoplasmic trees have so far only been observed in C. pachyderma and enabled the tree-forming foraminifera to elevate itself above ground. (c) Ectoplasmic “twigs” were used to guide and hold the more delicate pseudopodial network when distributed into prevailing currents and were, in our experiments, also only developed in C. pachyderma specimens. Relocation of a specimen usually required it to tear apart and leave behind the rigid ectoplasmic structures and eventually also the envelope surrounding the test. Apparently, these rigid structures could not be resorbed or reused.

Microstructural and biomolecular preservation is reported in fossils as old as the Triassic. Such preservation suggests unusual taphonomic conditions. We collected fragments of fossil whale bone from silty, tuffaceous, and diatomaceous rocks of the middle-upper Miocene portion of the Pisco Formation. The whale fossils within the region are generally well-preserved and mostly articulated, including some specimens with in situ baleen. Due to the depositional setting associated with the preservation of these fossils, they could be expected to be favorable candidates for the preservation of cellular microstructures and/or original biomolecules. To test this hypothesis, fossil whale bone fragments were subjected to microscopic analysis and EDTA-mediated demineralization to release extractable materials. Microscopy of partially demineralized fossil bones revealed quartz-permineralized osteocyte-like and vessel-like structures. Protein assay (micro-Bicinchoninic Acid Assay) of the supernatants obtained from demineralized fossils yielded 12 to 19.5 μg of protein per gram of bone. MALDI-TOF analysis of the extracted protein demonstrated the presence of approximately 5 kD molecules in one fossil sample, consistent with the presence of highly fragmented polypeptides. An LC-MS/MS analysis of the fragmentation pattern of the tryptic digest of extracted protein was performed. However, attempted protein identification was unsuccessful. Nevertheless, this study first documents the microstructural preservation with some silicification of the fossil whale bones of the Pisco Formation, and then quantifies extractable protein from these bones. It adds to the growing body of reports of microstructural and organic preservation in fossils.

Highlight Light intensity from plastic waste was positively correlated with the abundance of zooxanthellae in corals. The abundance of zooxanthellae between sack plastic and clear plastic treatment tended to be the same. The treatment of packaging plastic was treated with the lowest light intensity. The treatment of black plastic was the treatment that produced the lowest abundance of zooxanthellae. Abstract Coral growth in Indonesia was being disrupted due to the continued threat of environmental change, such as littering to the beach. This study aimed to analyze the effect of the attachment of different colored plastic waste to the rate of zooxanthellae abundance on branching corals in Kelapa Dua Island waters. Branching coral colony samples consisted of the genus Acropora and Porites with a total of 15 fragments of coral colonies at the depth of 80-90 cm were tested with a treatment of the attachment plastic wastes (control, clear plastic, plastic sack, plastic packaging, and black plastic) for four days. The zooxanthellae abundance was calculated using the APHA (American Public Health Association) formula. The results of zooxanthellae abundance on the closure treatment of branching coral samples with black plastic and control had the lowest and highest values by 4.25 x 10 5 cells/cm 2 and 1.38 x 10 6 cells/cm 2 . The results of the linear regression test showed that there was a significant relationship between plastic waste with low light intensity and a decrease of zooxanthellae abundance in coral colonies with the equation Y of 972.78x + 653402, determination index (R2) of 0.68, and correlation index (r) of 0.83. These results indicated that the attachment of plastic waste to branching coral colonies could be a stressor on coral animals in reducing light intensity, which caused a reduction of zooxanthellae abundance as coral endosymbiont.

Worldwide, lobsters are considered important predators of macroalgae-consuming urchin species, but this has not been tested for Australia’s common lobster, the eastern rock lobster (Sagmariasus verreauxi). We predicted that the abundant urchins, the long-spined urchin (Centrostephanus rodgersii) and the short-spined urchin (Heliocidaris erythrogramma), would form substantial components of lobster diets. To test this hypothesis, we examined 115 lobster stomachs from 9 locations and conducted 14 feeding trials, in which lobsters were offered either urchin species. Dissections revealed various stomach items, with detritus (51%), bivalves (34%), gastropods (28%) and algae (26%) occurring more frequently than urchins (19%). Urchin spines were found in 22 lobsters that ranged in size from 91- to 124-mm carapace length, with all individuals containing H. erythrogramma spines and C. rodgersii spines observed only once. During feeding trials, seven urchins were consumed. Four H. erythrogramma were eaten on Day 1, whereas one was not eaten until Day 11. Two C. rodgersii were eaten on Days 2 and 10. Only three of the six lobsters observed to eat urchins ingested spines. Together, these data show that S. verreauxi is a generalist predator that consumes urchins, although, because urchins could be eaten without ingesting spines, future studies are needed to assess the importance of urchins as dietary items for S. verreauxi.

Testate amoebae are a highly diverse and polyphyletic group of heterotrophic, free-living amoeboid protists that consist of a single cell enclosed within a shell, or test. These organisms i...

Flabellina rubrolineata was believed to have a wide distribution range, being reported from the Mediterranean Sea (non-native), the Red Sea, the Indian Ocean and adjacent seas, and the Indo-West Pacific and from Australia to Hawaii. In the present paper, we provide a redescription of Flabellina rubrolineata, based on specimens collected near the type locality of this species in the Red Sea. The morphology of this species was studied using anatomical dissections and scanning electron microscopy. To place this species in the phylogenetic framework and test the identity of other specimens of F. rubrolineata from the Indo-West Pacific we sequenced COI, H3, 16S and 28S gene fragments and obtained phylogenetic trees based on Bayesian and Maximum likelihood inferences. Our morphological and molecular results show a clear separation of F. rubrolineata from the Red Sea from its relatives in the Indo-West Pacific. We suggest that F. rubrolineata is restricted to only the Red Sea, the Arabian Sea and the Mediterranean Sea and to West Indian Ocean, while specimens from other regions belong to a complex of pseudocryptic species.

Organisms have limited resources available to invest in reproduction, causing a trade‐off between the number and size of offspring. One consequence of this trade‐off is the evolution of disparate egg sizes and, by extension, developmental modes. In particular, echinoid echinoderms (sea urchins and sand dollars) have been widely used to experimentally manipulate how changes in egg size affect development. Here, we test the generality of the echinoid results by (a) using laser ablations of blastomeres to experimentally reduce embryo energy in the asteroid echinoderms (sea stars), Pisaster ochraceus and Asterias forbesi and (b) comparing naturally produced, variably sized eggs (1.7‐fold volume difference between large and small eggs) in A. forbesi. In P. ochraceus and A. forbesi, there were no significant differences between juveniles from both experimentally reduced embryos and naturally produced eggs of variable size. However, in both embryo reduction and egg size variation experiments, simultaneous reductions in larval food had a significant and large effect on larval and juvenile development. These results indicate that (a) food levels are more important than embryo energy or egg size in determining larval and juvenile quality in sea stars and (b) the relative importance of embryo energy or egg size to fundamental life history parameters (time to and size at metamorphosis) does not appear to be consistent within echinoderms., In two species of sea stars, exogenous food levels are more important than maternal investment in determining larval and juvenile quality. The relative importance of maternal investment to fundamental life history parameters (time to and size at metamorphosis) does not appear to be consistent within echinoderms.

Specimens displaying unusual ( " abnormal " or aberrant) test morphologies, for example, the presence of twin embryos, or test repair after damage, are reported from Lower Cretaceous Orbitolinidae. Twin embryos (which have not always been recognized as such in the literature) are described from the upper Barremian of Tibet and France (Palorbitolina lenticularis), the upper Albian of Somalia (Orbitolina gr. sefini), and the upper Aptian-early Albian of Texas (e.g., Mesorbitolina texana). Twin embryos have so far only been reported from the Orbitolininae (with complex embryo), and not from the Dictyoconinae (with simple embryo). Repaired partially damaged tests (the damage possibly caused by predation or mechanical fracture) are observed in lower Aptian orbitolinids from Iran. Regeneration after damage (bioadjustment) leads to malformed tests.

It is generally assumed that the soil environment played an important role in the evolution of life on land, as a transition medium between water and air. This idea was already formulated by M.S. Gilharov in 1949 but it has never been tested systematically against modern phylogenetic reconstructions from DNA data. In this paper I review the phylogenies of soil invertebrate lineages that have been published in the last decade, as a guide to test Ghilarov’s hypothesis. I propose to distinguish between major and minor terrestrializations and six different evolutionary scenarios. The various lineages of soil invertebrate (nematodes, tardigrades, crustaceans, apterygotes, insects, myriapods, chelicerates, flatworms, earthworms, potworms and snails) show different pathways of terrestrialization. Some lineages seem to have conquered the land directly from the marine environment, others through intermediate habitats (intertidal, caves and freshwater). The review illustrates that the study of soil invertebrates holds many promises for enriching evolutionary sciences.

Spores of mushroom-forming fungi are thought to be passively dispersed by wind. Studies of the spore morphology and ecological studies suggest, however, that dispersal by animals might also play a role. Since simultaneous and long-term observations of fungus-animal interactions are not feasible, we test the efficiency of time-lapse camera surveys followed by motion detection analysis. We surveyed 21 mushrooms of seven species for three days (daytime). We found mainly insects, with an average activity of 481 visits per fungal species per day. The estimated average animal size was 18 mm2. Due to the small animal size, the image quality did not allow detailed taxon identification. Animal activity on Lactarius vellereus was significantly higher than on all other species. In general, the more light-colored and larger mushrooms and species with ornamented spores showed higher activity. A test for false negatives, however, suggests that background color lightness potentially biases results. Camera surveys could thus contribute to the study of fungus-animal interactions. However, the use of higher-resolution images, 24 h survey and a reduction of the bias caused by background lightness are necessary.

Niche specificity can predispose species to population declines during periods of resource limitation, yet trophic niche specificity is poorly known for many small-bodied freshwater fishes. Applying a two-tiered approach involving stomach content and stable isotope analyses, we examined the diet and trophic niche of the threatened eastern sand darter (Ammocrypta pellucida (Putnam, 1863)) and co-occurring fishes in the Thames River, Ontario, Canada. As with previous studies, stomach content analysis revealed that eastern sand darter consumed a variety of benthic organisms including Chironomidae, Cladocera, Ostracoda, Oligochaeta, and Ephemeroptera; however, proportional contributions of prey groups differed based on stable isotope analysis, highlighting the potential for seasonal variation in prey consumption. Despite evidence of a generalist strategy, stable isotope analysis indicated eastern sand darter exhibited a relatively narrow trophic niche relative to co-occurring fishes. Trophic niche overlap was relatively minor between eastern sand darter and drift-feeding fishes (spotfin shiner (Cyprinella spiloptera (Cope, 1867)), emerald shiner (Notropis atherinoides Rafinesque, 1818), and buffalo sp. (genus Ictiobus Rafinesque, 1820)), but was more evident between eastern sand darter and benthic and benthopelagic fishes (johnny darter (Etheostoma nigrum Rafinesque, 1820) and blackside darter (Percina maculata (Girard, 1859))), indicating that competition with these species may be more likely during periods of prey scarcity.

Diatoms are among the most commonly used bioindicators. Correct taxonomic identifications are critical to their use as bioindicators because closely related diatom species can respond diffe...

Walde, D.H.-G., Weber, B., Erdtmann, B.-D. & Steiner, M. 20 June 2019. Taphonomy of Corumbella werneri from the Ediacaran of Brazil: sinotubulitid tube or conulariid test? Alcheringa 43, 335–350. I...

Mammals adapted to unpredictable and low-energy environments often evolve a “bet-hedging” life history strategy characterized by less costly reproductive outputs over a longer and slower-growing life. In contrast, species adapted to more predictable (i.e., low variation) and higher energy environments may evolve greater fecundity over a shorter and faster-growing life. We tested whether this known interspecific pattern also occurs within a species. We compared life history traits of the ringed seal (Pusa hispida) in the Canadian High Arctic to those closer to the southern limit of the species' circumpolar distribution. We found that northern seals grew slower than southern seals (Brody growth coefficient), achieved a greater asymptotic body weight (82 and 69 kg vs. 74 and 54 kg female and male, respectively), reached sexual maturity later (6.1 years vs. 4.5 years), had lower fecundity (1.8 years vs. 1.3 years interbirth interval), longer average lifespan (5 years vs. 3 years median age), and greater movements (1,269 vs. 681 km). Mating systems also likely differed with northern seals showing morphological evidence of a promiscuous mating system with potential sperm competition as indicated by greater relative testes size. The northern region was also characterized by more unpredictable environmental timing of seasonal events, such as spring sea ice breakup. Life history variation between the intraspecific groups of seals appears to agree with interspecific patterns and provides a better understanding of how species' life history parameters shift in concert with environmental conditions.

The isolated tributary hypothesis (ITH) states that headwater tributaries are insular habitats, and therefore, populations in tributaries will have low genetic connectivity. We compared gen...

The research about species richness pattern and elevational Rapoport's rule (ERR) have been carried out mostly in the temperate regions in the recent years and scarcely in the tropical mountains; meanwhile, it is unclear whether the ERR is consistent among different life‐forms and phytogeographic affinities. Here, we compiled a database of plant species of Mount Kenya, a tropical mountain of East Africa, and divided these species into twelve groups depending on the life‐form and phytogeographic affinity of each species. We inspected the species richness pattern of each group along the elevation gradient and also tested ERR of each group using Stevens' method. Our results showed that species richness of the total species showed a positively skewed (hump‐shaped) pattern along the elevation gradient and different life‐forms and phytogeographic affinities showed similar hump‐shaped patterns as the total species. The average elevation range size of the total species and herbaceous species showed increasing patterns along the elevation gradient, while lycophytes and ferns, and woody species showed an obvious downward trend after peaking in the high elevation regions. We concluded that the widely distributed herbaceous species which also have broad elevation range sizes are more applicable to ERR, while the narrowly distributed woody species with small elevation range sizes occurring in the higher elevations could reverse ERR. Therefore, we concluded that the ERR is not consistent among different organisms in the same region.

The phytotechnology concept that is applied for a bio-desalination reactor become a new desalination technology. The desalination technology can be called as bio-desalination technology to remove ions of Na+ and Cl- in brackish or saline water using mangrove plant. Before the mangrove plants were used in bio-desalination technology, the preliminary phytotoxicity test was conducted. The purpose was to determine the salinity concentration at which the mangrove species of Rhizophora mucronata can survive. The preliminary phytotoxicty test was carried out using a plastic reactor that was designed as a reed bed system. The reactors filled with gravel, sand, and artificial saline water. The variation of the NaCl concentrations were 0 mg/L as control, 10,000; 20,000; 30,000; 40,000, and 50,000 mg/L. The physical observation of the survival condition of Rhizophora mucronata was carried out during the preliminary test for 7 days. The analysis of Scanning Electron Microscopy (SEM) on Rhizophora mucronata was conducted at the end of exposure. The results showed that Rhizophora mucronata could not survive at the concentrations of 40,000 and 50,000 mg/L. Rhizophora mucronata changed the color of the leaves to brown and the stems become softer. Multiple cell damage and the decreasing trend of sodium and chloride amounts occured on roots and stems at the salinity concentration of 50,000 mg/L. In conclusion, the high of salinity concentration (> 30,000 mg/L) can be toxic to Rhizophora mucronata.

Chlorine efficacy as a biocide for ballast water treatment was investigated under cold- and warm-water temperatures across winter and summer seasons. Freshwater phytoplankton samples were collected and acclimated under in situ environmental conditions ranging from 2 to 22 °C. Samples were exposed to seven chlorine treatments (from 0.02 to 5.0 ppm), in addition to a control (0.0 ppm). Free-chlorine concentrations, phytoplankton abundance, and photosynthetic efficiency were measured up to 48 h following treatment. After 4 h of treatment at concentrations less than 0.22 ppm, phytoplankton densities were reduced by more than 50%, without cell resurgence. Similar reduction was recorded immediately after exposure when chlorine concentrations were higher than 3.0 ppm. After 8 h, free chlorine neared 0.0 ppm for initial chlorine concentrations below 1.2 ppm, irrespective of temperature regime. Winter phytoplankton exhibited slightly lower mortality to chlorine exposure regardless of the temperature, although they also exhibited lower photosynthetic efficiency. Despite a general absence of significant effect of temperature on the chlorine decay, our results suggest that higher doses of chlorine or longer exposure times may be required during winter to achieve full treatment effect. Tests at large scales are needed to further confirm these findings.

Shallow-water marine invertebrates living near the upper limits of their thermal tolerances are uniquely susceptible to climate warming. This is particularly the case for species that occur in geographic regions where larval dispersal or adult migration to cooler waters is not an option. This scenario aptly describes populations of the seagrass-associated sea urchin Lytechinus variegatus inhabiting the northern Gulf of Mexico where northward movement is restricted by a coastline. In the present study, we exposed juvenile L. variegatus to chronic ambient (26 °C) and predicted near-future (30 °C) temperature treatments for 90 days. X-ray Diffraction (XRD) was employed to determine the Mg/Ca ratios of the spines, test, and Aristotle's lantern of individuals sub-sampled at 30, 60, and 90 days. We found that while individuals grew at similar rates, Mg/Ca ratios in all skeletal components were overall significantly lower in individuals held at 30 °C than at 26 °C.

A new species of clypeasterid sea biscuit, Clypeaster brigitteae n. sp., is described from material collected in the Philippines at depths between 100 and 200 m. The new taxon increases the number of Clypeaster species recorded from the Philippines to nine, representing nearly a quarter of the world’s diversity of the genus. Other Philippine species include: C. annandalei Koehler, 1922; C. fervens Koehler, 1922; C. humilis (Leske, 1778); C. japonicus Döderlein, 1885; C. latissimus (Lamarck, 1816); C. pateriformis Mortensen, 1948; C. reticulatus (Linnaeus, 1758); and C. virescens Döderlein, 1885. Using type material where available, each of these species is compared and contrasted with C. brigitteae n. sp. in tables consisting of new data derived from general test shape and size, petal structure, food grooves, plate architecture, internal structure, and morphology of spines, pedicellariae, and tube feet.

The echinoid Homolampas fragilis (A. Agassiz,1869) (Echinodermata) is recorded for the first time in the Brazilian coast from the Continental shelf of the State of Ceara. The specimens were classified based on their distinct morphological characters, including the fragile test, primary tubercles non-crenulated and with deep areoles, absent peripetalous fasciole, without aboral tubercles on the interambulacrum 5, three to four genital pores, and posterior prolongation of the labrum, not reaching the second adjacent labral plate narrow and wedge-shaped, extending to second or third ambulacral plate; only just contacting sternal ambulacral plates. This species usually inhabits tropical waters from the Caribbean Sea, Gulf of Mexico, and Florida Strait. Its bathymetry is expanded from 360–3550 to 34–3550 m deep. In the present work, we provide morphological and geographical updates on Homolampas fragilis found in the Brazilian coast.

The detection of light intensity and subsequent phototaxis are essential for the fitness of sea urchins in intertidal and shallow subtidal waters, where light intensity varies in accordance with the depth and other hydrographic conditions. The molecular basis of photoresponse, however, remains largely unknown. We compared the expression of SiOpsin4, SiPax6, and SiOpsin5 among tube feet, coelomocytes, gonads, and gut of the sea urchin Strongylocentrotus intermedius. All three genes showed the significantly highest expression in tube feet. To test whether r‐opsin genes (for example, Opsin4) and Pax6 in tube feet, rather than chaopsin genes (for example, Opsin5), are involved in the molecular responses to light intensity, we investigated the expression of Opsin4, Pax6, and Opsin5 among four light intensities. Both Opsin4 and Pax6 expressions were significantly higher in the sea urchins at 1,500 lx than at 100, 300, and 700 lx, indicating a co‐upregulation of Opsin4 and Pax6 expressions in sea urchins exposed to the high light intensity (for example, 1,500 lx). However, there was no significant difference of SiOpsin5 expression among the four light intensity groups. Consistent with our hypothesis, there was no significant difference in either Opsin4 or Pax6 expression between the two light intensity environments (low light intensity environment: 50–100 lx; high light intensity environment: 330–1400 lx). This indicates that positive phototaxis and negative phototaxis probably regulate the expression of Opsin4 and Pax6 to a similar level when sea urchins are exposed to the high and low light intensities, respectively. The present study provides new insights into the molecular basis of light intensity detection and subsequent phototaxis of eyeless species.

In this study, we performed comprehensive pathology examinations on 83 Tripneustes ventricosus from 11 locations on St. Kitts to build baseline data necessary for disease diagnosis in this species. Gross abnormalities were observed in 23/83 (28%) urchins and included spine loss, visceral hyperpigmentation, test discoloration, and test ulceration. Ciliates were the only protists identified in this study via examination of tissue wet mounts and histology, documented in 50/83 (60%) urchins. Microscopic observations associated with visibly abnormal status included muscle necrosis, test and appendage inflammation, appendage (tube feet, spines, and pedicellariae) degeneration, severe coelomocytosis, and generalized hypermelanosis. Enterocyte intranuclear inclusion bodies, microbial aggregates, nerve pigmentation, enteric pigmentation, integument-associated crustaceans, and encysted metazoan parasites were of uncertain pathological significance. The etiology for any lesion was not microscopically apparent, contrasting literature implicating common marine bacteria in urchin diseases. This study highlights the importance of histopathology in urchin disease investigations and facilitates the recognition of disease in T. ventricosus.

International audience; This paper investigates whether morphological variability of test and Aristotle's lantern can be detected in sea urchins exposed to domestic pollution and whether this variability can be also related to tidal level and hydrodynamic features. The study was conducted on four sites along the French Basque coast. Each site is characterized by its geological layers’ orientation, regardless of its proximity to sewage outlets. Analyses on high-resolution pictures of jaws were performed and three parameters were retained: length, height and demipyramid dry mass. Five shape descriptors were consequently defined regarding the test and the jaws. Individuals with heavy test density associated with highly developed demipyramid regarding test diameter and height were preferentially observed in intertidal areas, remoteness from treatment plants and in south-oriented geological layers. High test hemispherical indice and demipyramid elongation indice were preferentially found far away from treatment plants. Results contribute to improving knowledge on pressure impact assessment and on state of the environment conservation in a defined area. It may also be useful to propose management measures on an appropriate scale for a species that is usually managed on a regional basis.

Synopsis Bioeroding organisms play an important part in shaping structural complexity and carbonate budgets on coral reefs. Species interactions between various bioeroders are an important area of study, as these interactions can affect net rates of bioerosion within a community and mediate how bioeroders respond to environmental change. Here we test the hypothesis that the biomass of endolithic bioeroding microalgae is positively associated with the presence of a macroboring bivalve. We compared the biomass and chlorophyll concentrations of microendolithic biofilms in branches of the coral Isopora palifera (Lamarck, 1816) that were or were not inhabited by a macroboring bivalve. Those branches with a macroborer present hosted ∼80% higher microbial biomass compared to adjacent branches from the same coral with no macroborer. Increased concentrations of chlorophyll b indicated that this was partly due to a greater abundance of green microalgae. This newly described association has important implications for the coral host as both the bivalve and the microalgae have been hypothesized as symbiotic.

Previous phylogenetic analysis based on combined mitochondrial and nuclear gene sequences detected paraphyly of the Typhlogammaridae. To test this hypothesis a portion of large subunit (LSU-rDNA) g...

Overgrazing can deplete macroalgal communities and lead to reduction of habitat complexity and species diversity. To quantify the effects of sea urchin and fish herbivory on the rocky reefs of the North Aegean Sea, a six-month grazer exclusion experiment was conducted at the southeastern part of Lesvos Island at three rocky reef sites at depths between 1.0 and 4.7 m. The aim was to test whether (a) algal growth is hampered by the combined grazing activity of sea urchins and fish, and (b) algal growth is suppressed by the foraging of fish alone. At each site, three replicate cage, cage-control, and control treatments were applied and sampled every two weeks using photoquadrats: (1) fully-closed cages that excluded both sea urchins and large herbivorous fish; (2) open-top cages that excluded sea urchins only; and (3) control surfaces with no restrictions on herbivores. Algal biomass was estimated based on the percentage cover values of the analyzed images. Underwater surveys for the estimation of sea urchin population density (by quadrat sampling) and total fish biomass (by strip transects) were also conducted. The main grazers observed were the sea urchins Arbacia lixula and Paracentrotus lividus, and the herbivorous fish Sarpa salpa. Herbivorous fish dominated fish communities, but the overall fish biomass density was relatively low. The experimental monitoring of algal biomass showed that erect algal growth was significantly higher inside the fully-closed cages in contrast to the respective controls. Overall, algal growth was significantly higher inside both types of cages, when compared to the control surfaces. No significant differences among the two types of cages were found in terms of total algal growth, indicating that urchin grazing was the most important factor causing the hampering of algal growth and altering the structure of the macroalgal community towards a sparse vegetation of low complexity devoid of erect algae, while herbivore fish had a minor effect.

Scleractinian corals are the host group with the greatest number of species associated with hydroids in the genus Zanclea. There are 34 nominal species and 31 genera of scleractinians reported as Zanclea hosts from a few localities across the Red Sea, Indo-Pacific, and Caribbean. However, little is known about how consistent and cosmopolitan scleractinian-Zanclea relationships are. To test their geographical consistency, we surveyed Fijian corals for Zanclea presence using both field-based surveys and analysis of in situ coral photographs. Surveys targeted 16 species and seven genera of reported Zanclea hosts and five other corals commonly found at the sites. We observed Zanclea hydroids associated with 22 species in seven genera of scleractinian corals with 17 (77%) of the species being newly reported hosts. Our findings suggest that a broad diversity of scleractinian corals hosting Zanclea remains to be documented, and although Zanclea-scleractinian associations are likely cosmopolitan in their distribution across localities, associations with specific coral species may not be.

The quantity of biomass in an ecosystem is constrained by energy availability. It is less clear, however, how energy availability constrains taxonomic and functional diversity. Competing models suggest biodiversity is either resource-limited or far from any bound. We test the hypothesis that functional diversity in marine bivalve communities is constrained by energy availability, measured as particulate organic carbon (POC) flux, in the modern oceans. We find that POC flux predicts the relative prevalence of ecological modes in both the Atlantic and Pacific Oceans. Moreover, the associations of ecological modes with POC fluxes are similar between the Atlantic and Pacific despite being based on independent sets of species, indicating a direct causal relationship. We then use the relationship between POC flux and the prevalence of functional groups in the modern to test the hypothesis that the trend of increasing functional diversity in bivalves across the past 500 Myr has occurred in response to increased POC flux. We find no evidence that the earliest-appearing modes of life are preferentially associated with low-POC environments or that the mean POC flux experienced by marine bivalves has increased across geological time. To reconcile the close association between ecological mode and POC flux in the modern oceans with the lack of evidence for increasing POC fluxes across time, we propose that POC flux has not increased substantially over time but, rather, the increase in bivalve functional diversity enabled bivalves to become more abundant, to occupy a broader range of environments, and to capture a greater fraction of the total POC flux. The results here suggest at the geographic scale of oceans and through geologic time bivalve diversity was not bounded by food availability.

The spatial distribution of healthy and diseased sponges in Lake Baikal was investigated. The endemic sponges were studied in May − June 2015 at 11 transects within the depth range of 0 to 40 m. More than 500 sponge specimens were collected, and 29 taxa including 12 species and 17 morphospecies (sp. taxa) were identified. Among the 29 taxa, only B. martinsoni specimens and 14 morphospecies were healthy, whereas specimens of the other 11 species and 3 morphospecies were diseased, making up 35% of the total number of specimens (512). The different body forms of sponge found among the specimens were encrusting (66%), globulous (21%), and branched (13%). Sponges with necrosis signs, discolored specimens or covered with violet film or brown spots, were found in all transects under study (37 stations of 68). The percent cover of the bottom (per m2) by various body forms of sponges was evaluated with a sponge faunal state assessment test. Changes in the diversity and abundance of sponges due to their disease may jeopardize the functioning of the entire ecosystem of Lake Baikal which is a World Heritage Site. This baseline data on patterns of sponges, including their spatial distribution and percent cover, will be utilized to support future management and monitoring of Lake Baikal. Data on the current state of Baikal endemic sponge fauna are essential for understanding the causes and prognosis of disease processes of freshwater sponges.

The Green sea urchin Strongylocentrotus droebachiensis is a cold-water species that in the 70s and 80s was the main culprit in the major grazing of macrophytes in the Norwegian fjords and coastal areas. Recent reports have questioned a decline in the S. droebachiensis in the Oslofjord, similar to what was observed to occur in the Norwegian coastal population of S. droebachiensis after the 1990s. In surveys from 2013 we collected data on urchin density, test diameter, early urchin settlement and Gonad Index and created a framework in order to investigate if the current Inner Oslofjord populations of S. droebachiensis are different from surveys conducted in 1979 and 1992. This study found significant differences in density, diameter and settlement over time. Highest density in 1992 was at 10 and 15 m, while being at 20 m in 2013. Urchin diameter at the station with most urchins was on average 5 cm in 1992 compared to 3 cm in 2013. Settlement differed both between the number of settlers between 1992 and 2013, and season for highest settlement (summer in 1992, and autumn in 2013). The inner Oslofjord sea urchin data indicate a still healthy population, although environmental data (as temperature and salinity) have changed to less favorable conditions for this species.

Carnivorous plants experience the same constraints as most predators, in that they must attract, capture, and consume prey. Natural populations of the yellow pitcher plant Sarracenia flava show most plants are composed of one to two ramets, with relatively few active leaves. An experiment was conducted to determine the effect of number of leaves on insect capture by creating spatially distinct S. flava groups of different sizes. Groups with more leaves attracted more prey, but prey capture per leaf was not correlated with group size. The per-leaf capture rate of different insect types, mostly wasps and bees, was also not correlated with group size. For this predator there was no advantage or disadvantage of foraging in groups.

Disease outbreaks and mass mortality events in terrestrial and marine taxa are increasing as a result of human influence, pollution, and climate change. Sea Star Wasting has become more common on the west coast of the United States, with increasing numbers of asteroids affected since 2013. Rising temperatures have traditionally been linked to mass mortality events, but other factors such as the effect of diet on individual susceptibility to Sea Star Wasting have not been examined. Here, we use laboratory experiments to test the frequencies of SSW sign onset and death of a native sea star when exposed to diets of two invasive ascidians. We show that prey identity affects mortality rates of affected predators. Sea stars that consumed Diplosoma listerianum experienced SSW signs, but 0% mortality, whereas animals that consumed Botrylloides violaceus, or no prey experienced 41% mortality. We expect that invader induced shifts in community species composition will increase the frequency of these mass die offs on both the west and east coasts.

Architecture, like nests, burrows, and other types of fortresses, may have played an important role in the evolution of social life on land. However, few studies have examined architecture in organisms that transitioned from sea to land to test how and why architectural and morphological changes might have jointly impacted social evolution. Here I contrasted the shell architecture and body morphology of two of the phylogenetically most closely-related land versus sea species of hermit crab (the terrestrial hermit crab, Coenobita compressus, and the marine hermit crab, Calcinus obscurus), as well as the original builder of their shells (the gastropod, Nerita scabricosta). In contrast to the shells of gastropods and marine hermit crabs, only the shells of terrestrial hermit crabs were architecturally remodeled, with no columella inside for the occupants to grip upon to resist eviction. The bodies of terrestrial hermit crabs were also significantly more exposed outside the enlarged openings of their remodeled shells, whereas the substantially smaller-bodied marine hermit crabs were safeguarded deep within the recesses of their unremodeled shells. Ultimately, these changes in shell architecture and body morphology likely had consequences for social evolution on land, making conspecifics not only more dependent upon one another for homes, but also potentially easier to evict. Further changes in claw shape on land (with the claws of terrestrial hermit crabs becoming shorter, wider, and thicker) may have evolved to help offset their heightened danger of social eviction, acting as a more effective door against conspecifics.

Leaf adpression fossils vary in their organic content, relief, and quality of preservation. Some of the most enigmatic adpressions, known as leaf molds, retain fine morphological and anatomical details despite being found in coarse sandstones—a widespread phenomenon attributed to the presence of fine-grained minerals on the fossil surface. Previous taphonomic studies have demonstrated the importance of microbial biofilms in promoting mineralization and argued that authigenic iron oxides can serve as the preserving medium. Here, we propose that this role is played more commonly by biologically precipitated aluminosilicate phases (clays). To test this hypothesis, we conducted energy dispersive X-ray spectroscopy (EDS) analysis of thin sections through fossil leaves from five localities differing in age and depositional environment. Point spectra taken directly from the leaf-sediment interface revealed that cation-rich clays separate the leaf fossils from the matrix. Additional EDS analyses of biofilms on a fossil leaf and on modern oak leaves decaying in freshwater also revealed aluminosilicates, for which we infer a biofilm-mediated, authigenic origin. These results are the basis of a novel ‘Biofilm-Clay Template' taphonomic model, whereby microbially mediated clay authigenesis is commonly the first step in leaf adpression preservation.

Ammonia aomoriensis (Asano 1951) was isolated from 78 samples collected from the Yellow Sea and East China Sea during 2010 to 2014. The species exhibits dimorphism (microspheric and megalospheric forms) and different coiling directions (dextral and sinistral). A fragment of SSU rDNA was sequenced for four specimens of A. aomoriensis exhibiting different morphologies (dextral vs. sinistral, microspheric vs. megalospheric). Our results show that A. aomoriensis from our study sites branch within previously obtained sequences of the same species. In order to test whether morphological differences are environmentally controlled we investigated 667 specimens from Qingdao and Jiaozhou Bay among which 290 were right coiled (dextral) and 377 were left coiled (sinistral). Similarly, 525 were microspheric and 142 were megalospheric. A correlation coefficient was computed to evaluate the relationship between foraminiferal morphology (dimorphism and coiling direction) and environmental parameters (temperature and salinity). A significant positive correlation was detected between the ratio of microspheric/megalospheric forms and salinity (r=0.719, p

Despite the evolutionary success and ancient heritage of the molluscan shell, little is known about the molecular details of its formation, evolutionary origins, or the interactions between the material properties of the shell and its organic constituents. In contrast to this dearth of information, a growing collection of molluscan shell-forming proteomes and transcriptomes suggest they are comprised of both deeply conserved, and lineage specific elements. Analyses of these sequence data sets have suggested that mechanisms such as exon shuffling, gene co-option, and gene family expansion facilitated the rapid evolution of shell-forming proteomes and supported the diversification of this phylum specific structure. In order to further investigate and test these ideas we have examined the molecular features and spatial expression patterns of two shell-forming genes (Lustrin and ML1A2) and coupled these observations with materials properties measurements of shells from a group of closely related gastropods (abalone). We find that the prominent “GS” domain of Lustrin, a domain believed to confer elastomeric properties to the shell, varies significantly in length between the species we investigated. Furthermore, the spatial expression patterns of Lustrin and ML1A2 also vary significantly between species, suggesting that both protein architecture, and the regulation of spatial gene expression patterns, are important drivers of molluscan shell evolution. Variation in these molecular features might relate to certain materials properties of the shells of these species. These insights reveal an important and underappreciated source of variation within shell-forming proteomes that must contribute to the diversity of molluscan shell phenotypes.

Increasing CO 2 concentration in the atmosphere during the last decades has led to a significant decrease in ocean pH. Organisms that need carbonate to build their calcareous skeletons could be severely affected . In this study we focused on the effects of ocean acidification on juveniles of the sea urchins Paracentrotus lividus and Diadema africanum . We assessed the effects of decreased pH on two skeletal structures, spines and test, and their impacts on species performance to avoid predation events in the field. Juveniles of both study species were exposed for 100 days to two treatments of pH: a pH of 8.0 (413.2 μatm) and pH of 7.6 (1349 μatm). Our results showed that D. africanum juveniles from the acidic treatment were more predated than those kept in the control treatment. These differences were not observed between treatments in P. lividus . Diadema africanum may be more sensitive to the indirect effects of ocean acidification on predator avoidance than P. lividus . However juveniles reared in a pH of 7.6 showed changes in shape in skeletal structures in both species. Considering these results in future scenarios, P lividus may be considered a “winning species”, and D. africanum a “losing species” in the climate change stake.

Sessile invertebrate prey that detect waterborne predator cues often respond by strengthening their structural defenses. Experimental evidence of the functional significance of such modifications using field-raised organisms is lacking. This study addresses that gap using intertidal mussels and predatory dogwhelks from Atlantic Canada. During the spring and summer of 2016, we ran a field experiment that manipulated dogwhelk presence to test their nonconsumptive effects on mussel traits. Dogwhelk cues elicited thickening at the lip, centre, and base of mussel shells, although simultaneously limiting shell growth in length. As shell mass was unaffected by dogwhelk presence, a trade-off between shell thickening and elongation was revealed. Thickening was strongest at the thinnest parts of the shell. Using the field-raised organisms, a lab experiment found that dogwhelks took, on average, 55 % longer to drill and consume mussels previously exposed to dogwhelk cues than mussels grown without such a cue exposure. Dogwhelks drilled at the thinnest parts of the shell but, nonetheless, the consumed cue-exposed mussels had thicker shells at the borehole than the consumed mussels not exposed to cues, which likely explains the observed difference in handling time. As handling time normally decreases predation success, this study indicates that the plastic structural modifications in mussels triggered by dogwhelk cues in the field hinder predation by these drilling predators.

The habitat-amount hypothesis challenges traditional concepts that explain species richness within habitats, such as the habitat-patch hypothesis, where species number is a function of patch size and patch isolation. It posits that effects of patch size and patch isolation are driven by effects of sample area, and thus that the number of species at a site is basically a function of the total habitat amount surrounding this site. We tested the habitat-amount hypothesis for saproxylic beetles and their habitat of dead wood by using an experiment comprising 190 plots with manipulated patch sizes situated in a forested region with a high variation in habitat amount (i.e., density of dead trees in the surrounding landscape). Although dead wood is a spatio-temporally dynamic habitat, saproxylic insects have life cycles shorter than the time needed for habitat turnover and they closely track their resource. Patch size was manipulated by adding various amounts of downed dead wood to the plots (similar to 800 m(3) in total);dead trees in the surrounding landscape (similar to 240 km(2)) were identified using airborne laser scanning (light detection and ranging). Over 3 yr, 477 saproxylic species (101,416 individuals) were recorded. Considering 20-1,000 m radii around the patches, local landscapes were identified as having a radius of 40-120 m. Both patch size and habitat amount in the local landscapes independently affected species numbers without a significant interaction effect, hence refuting the island effect. Species accumulation curves relative to cumulative patch size were not consistent with either the habitat-patch hypothesis or the habitat-amount hypothesis: several small dead-wood patches held more species than a single large patch with an amount of dead wood equal to the sum of that of the small patches. Our results indicate that conservation of saproxylic beetles in forested regions should primarily focus on increasing the overall amount of dead wood without considering its spatial arrangement. This means dead wood should be added wherever possible including in local landscapes with low or high dead-wood amounts. For species that have disappeared from most forests owing to anthropogenic habitat degradation, this should, however, be complemented by specific conservation measures pursued within their extant distributional ranges.

Early Ordovician (early Floian) reefs of South China include lithistid sponge–Calathium reefs with a three-dimensional skeletal framework. These structures are among the first post-Cambrian skeletal-dominated reef structures and provides an opportunity to test how the novel metazoan builders changed the environments and increased topographic complexity within benthic communities. We document the oldest labechiid stromatoporoid (Cystostroma) in a lithistid sponge–Calathium reef of the Hunghuayuan Formation in southeastern Guizhou, South China. These earliest stromatoporoids may have originated in reefs, and we argue that the complex topography created by the hypercalcified sponge Calathium facilitated the emergence of stromatoporoids. Beyond Cystostroma, keratose sponges, Pulchrilamina (hypercalcified sponge) and bryozoans have also inhabited in the micro-habitats (cavities and hard substrates) provided by Calathium. These findings suggest that ecosystem engineering by Calathium played an important role in the further diversification of reefs during the Ordovician.