Shallow-water Invertebrates Research Articles

Historical data on shallow-water invertebrates in Palu Bay, Indonesia to address the “Shifting Baselines” syndrome

As global change accelerates in the Anthropocene, the “shifting baselines” paradigm is also exacerbated. In this context, it is important to make historical data available in order to assist in evaluating and mitigating the changes occurring. Even though data from the first two decades of the 21st Century do not represent a pristine or true baseline condition, it is important to collate and curate data from this period. Unfortunately, many data are unpublished or stored in temporary repositories for a short time horizon (e.g. 3-10 years) or in printed format only, greatly limiting detection and access. We present data from four studies on shallow water invertebrates in Palu Bay collected over the period from 2008 to 2010. The taxonomic groups covered are Molluscs (Gastropods), Echinoderms and Cnidaria (corals), with some data on other taxa. These data will be of especial interest as a reference in evaluating the condition and recovery of the coastal ecosystems of Palu Bay after the 2018 tsunami.

Molecular Response to High Hydrostatic Pressure: Time-Series Transcriptomic Analysis of Shallow-Water Sea Cucumber Apostichopus japonicus.

Hydrostatic pressure is a key environmental factor constraining the benthic migration of shallow-water invertebrates. Although many studies have examined the physiological effects of high hydrostatic pressure on shallow-water invertebrates, the molecular response to high pressure is not fully understood. This question has received increasing attention because ocean warming is forcing the bathymetric migrations of shallow-water invertebrates. Here, we applied time-series transcriptomic analysis to high-pressure incubated and atmospheric pressure-recovered shallow-water sea cucumber (Apostichopus japonicus) to address this question. A total of 44 samples from 15 experimental groups were sequenced. Our results showed that most genes responded to pressure stress at the beginning when pressure was changed, but significant differences of gene expression appeared after 4 to 6 h. Transcription was the most sensitive biological process responding to high-pressure exposure, which was enriched among up-regulated genes after 2 h, followed by ubiquitination (4 h), endocytosis (6 h), stress response (6 h), methylation regulation (24 h), and transmembrane transportation (24 h). After high-pressure incubation, all these biological processes remained up-regulated within 4–6 h at atmospheric pressure. Overall, our results revealed the dynamic transcriptional response of A. japonicus to high-pressure exposure. Additionally, few quantitative or functional responses related to A. japonicus on transcriptional level were introduced by hydrostatic pressure changes after 1 h, and main biological responses were introduced after 4 h, suggesting that, when hydrostatic pressure is the mainly changed environmental factor, it will be better to fix sea cucumber samples for transcriptomic analysis within 1 h, but 4 h will be also acceptable.

Regional patterns in shallow water invertebrate assemblages on offshore oil and gas platforms along the Pacific continental shelf

We explored biogeographical and local patterns in the composition of shallow water (≤18 m depth) invertebrate assemblages inhabiting California offshore oil and gas platforms using multivariate analysis of diver- conducted photographic data collected from 23 platforms in 2013–2014. We evaluated the potential importance of sea surface temperature (SST) and other physical and biological factors in driving observed patterns in these assemblages. Prior to this analysis, platforms were grouped into four regions based on local differences in annual mean SST. The composition of invertebrate assemblages varied significantly among the four regions, reflecting differences in the relative abundances of certain anemone, bryozoan, sponge, and bivalve taxa. However, invertebrate assemblages varied idiosyncratically among platforms within a region. Variation in platform assemblages was associated with SST across regions; however, assemblages of platforms in the southeast Santa Barbara Channel were distinct due to the high cover of a non-native bryozoan, Watersipora subatra (Ortmann, 1890). The existence of geographical patterns in the composition of platform invertebrate assemblages and the colonization of one platform by a native bryozoan with southern affinities during elevated SST of 2014–2015 suggest that these assemblages may be useful over broad spatial scales as barometers of short- and longer-term changes in ocean climate. However, over smaller spatial scales, the idiosyncratic differences in invertebrate assemblages among platforms within regions indicates that these assemblages would have to be considered on a platform-by-platform basis under various decommissioning scenarios.

Population substructure and signals of divergent adaptive selection despite admixture in the sponge Dendrilla antarctica from shallow waters surrounding the Antarctic Peninsula.

Antarctic shallow-water invertebrates are exceptional candidates to study population genetics and evolution, because of their peculiar evolutionary history and adaptation to extreme habitats that expand and retreat with the ice sheets. Among them, sponges are one of the major components, yet population connectivity of none of their many Antarctic species has been studied. To investigate gene flow, local adaptation and resilience to near-future changes caused by global warming, we sequenced 62 individuals of the sponge Dendrilla antarctica along the Western Antarctic Peninsula (WAP) and the South Shetlands (spanning ~900km). We obtained information from 577 double digest restriction site-associated DNA sequencing (ddRADseq)-derived single nucleotide polymorphism (SNP), using RADseq techniques for the first time with shallow-water sponges. In contrast to other studies in sponges, our 389 neutral SNPs data set showed high levels of gene flow, with a subtle substructure driven by the circulation system of the studied area. However, the 140 outlier SNPs under positive selection showed signals of population differentiation, separating the central-southern WAP from the Bransfield Strait area, indicating a divergent selection process in the study area despite panmixia. Fourteen of these outliers were annotated, being mostly involved in immune and stress responses. We suggest that the main selective pressure on D.antarctica might be the difference in the planktonic communities present in the central-southern WAP compared to the Bransfield Strait area, ultimately depending on sea-ice control of phytoplankton blooms. Our study unveils an unexpectedly long-distance larval dispersal exceptional in Porifera, broadening the use of genome-wide markers within nonmodel Antarctic organisms.

Patterns and drivers of species diversity in the Indo‐Pacific red seaweed Portieria

AbstractAimBiogeographical processes underlying Indo‐Pacific biodiversity patterns have been relatively well studied in marine shallow water invertebrates and fishes, but have been explored much less extensively in seaweeds, despite these organisms often displaying markedly different patterns. Using the marine red alga Portieria as a model, we aim to gain understanding of the evolutionary processes generating seaweed biogeographical patterns. Our results will be evaluated and compared with known patterns and processes in animals.LocationIndo‐Pacific marine region.MethodsSpecies diversity estimates were inferred using DNA‐based species delimitation methods. Historical biogeographical patterns were inferred based on a six‐gene time‐calibrated phylogeny, distribution data of 802 specimens, and probabilistic modelling of geographical range evolution. The importance of geographical isolation for speciation was further evaluated by population genetic analyses at the intraspecific level.ResultsWe delimited 92 candidate species, most with restricted distributions, suggesting low dispersal capacity. Highest species diversity was found in the Indo‐Malay Archipelago (IMA). Our phylogeny indicates that Portieria originated during the late Cretaceous in the area that is now the Central Indo‐Pacific. The biogeographical history of Portieria includes repeated dispersal events to peripheral regions, followed by long‐term persistence and diversification of lineages within those regions, and limited dispersal back to the IMA.Main conclusionsOur results suggest that the long geological history of the IMA played an important role in shaping Portieria diversity. High species richness in the IMA resulted from a combination of speciation at small spatial scales, possibly as a result of increased regional habitat diversity from the Eocene onwards, and species accumulation via dispersal and/or island integration through tectonic movement. Our results are consistent with the biodiversity feedback model, in which biodiversity hotspots act as both “centres of origin” and “centres of accumulation,” and corroborate previous findings for invertebrates and fish that there is no single unifying model explaining the biological diversity within the IMA.

Neogene Proto-Caribbean porcupinefishes (Diodontidae).

Fossil Diodontidae in Tropical America consist mostly of isolated and fused beak-like jawbones, and tooth plate batteries. These durophagous fishes are powerful shell-crushing predators on shallow water invertebrate faunas from Neogene tropical carbonate bottom, rocky reefs and surrounding flats. We use an ontogenetic series of high-resolution micro CT of fossil and extant species to recognize external and internal morphologic characters of jaws and tooth plate batteries. We compare similar sizes of jaws and/or tooth-plates from both extant and extinct species. Here, we describe three new fossil species including †Chilomycterus exspectatus n. sp. and †Chilomycterus tyleri n. sp. from the late Miocene Gatun Formation in Panama, and †Diodon serratus n. sp. from the middle Miocene Socorro Formation in Venezuela. Fossil Diodontidae review included specimens from the Neogene Basins of the Proto-Caribbean (Brazil: Pirabas Formation; Colombia: Jimol Formation, Panama: Gatun and Tuira formations; Venezuela: Socorro and Cantaure formations). Diodon is present in both the Atlantic and Pacific oceans, whereas the distribution of Chilomycterus is highly asymmetrical with only one species in the Pacific. It seems that Diodon was as abundant in the Caribbean/Western Atlantic during the Miocene as it is there today. We analyze the paleogeographic distribution of the porcupinefishes group in Tropical America, after the complete exhumation of the Panamanian isthmus during the Pliocene.

Chemical and biological screening of deep-water sponges from Antarctic regions

The majority of marine natural products (MNPs) originate from tropical and temperate shallow water invertebrates, such as sponges [1]. Recent studies indicate the presence of great genetic diversity in deep-waters that may be linked to unprecedented chemistry due to evolution/adaptation to extremely harsh environmental conditions. However, only less than 2% of MNPs derive from the deep-sea organisms [2]. Antarctic ecosystems are rich in biodiversity [3] and exposed to unique environmental characteristics resulting in communities structured both by biotic interactions (e.g. predation, competition) and abiotic factors (e.g. seasonality, ice-scouring) [4], suggesting a high chemical diversity. In this work, we investigated 39 deep-water sponges collected from the Antarctic Weddell Sea and adjacent areas (depths -100 – 600 m). The freeze-dried sponge samples were extracted with water, followed by MeOH and CH2Cl2 separately. The combined organic extracts were tested for activity against cancer cells [HepG2 (liver) and HT29 (bowel) cancer cell lines], bacteria [ESKAPE panel: Enterococcus faecalis, Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli) and fungi (yeasts Candida albicans, Cryptococcus neoformans). Several Latrunculia sponge extracts displayed high anticancer activity against both cell lines (IC50 values 0.50 – 3.16 µg/ml). The organic extract of the glass sponge Rossella cf. antarctica showed moderate antibiotic activity towards MRSA and E. faecalis with IC50 values of 96 and 213 µg/ml, respectively. All extracts have undergone chemical profiling/dereplication studies by HPLC-DAD-MS and 1H NMR spectroscopy. The results of chemical and biological screening will assist in selection and activity-guided isolation of Antarctic deep-water sponge metabolites.

Characterising multi-level effects of acute pressure exposure on a shallow-water invertebrate: insights into the kinetics and hierarchy of the stress response.

Hydrostatic pressure is an important, ubiquitous, environmental variable of particular relevance in the marine environment. However, it is widely overlooked despite recent evidence that some marine ectotherms may be demonstrating climate-driven bathymetric range shifts. Wide-ranging effects of increased hydrostatic pressure have been observed from the molecular through to the behavioural level. Still, no study has simultaneously examined these multiple levels of organisation in a single experiment in order to understand the kinetics, hierarchy and interconnected nature of such responses during an acute exposure, and over a subsequent recovery period. Here, we quantify the transcription of a set of previously characterised genes during and after acute pressure exposure in adults of the shrimp Palaemonetes varians. Further, we perform respiratory rate and behavioural analysis over the same period. Increases in expression of genes associated with stress and metabolism were observed during and after high-pressure exposure. Respiratory rate increased during exposure and into the recovery period. Finally, differential behaviour was observed under elevated hydrostatic pressure in comparison to ambient pressure. Characterising generalised responses to acute elevated pressure is a vital precursor to longer-term, acclimation-based pressure studies. Results provide a novel insight into what we term the overall stress response (OSR) to elevated pressure; a concept that we suggest to be applicable to other environmental stressors. We highlight the importance of considering more than a single component of the stress response in physiological studies, particularly in an era where environmental multi-stressor studies are proliferating.

Light‐driven tipping points in polar ecosystems

Some ecosystems can undergo abrupt transformation in response to relatively small environmental change. Identifying imminent 'tipping points' is crucial for biodiversity conservation, particularly in the face of climate change. Here, we describe a tipping point mechanism likely to induce widespread regime shifts in polar ecosystems. Seasonal snow and ice-cover periodically block sunlight reaching polar ecosystems, but the effect of this on annual light depends critically on the timing of cover within the annual solar cycle. At high latitudes, sunlight is strongly seasonal, and ice-free days around the summer solstice receive orders of magnitude more light than those in winter. Early melt that brings the date of ice-loss closer to midsummer will cause an exponential increase in the amount of sunlight reaching some ecosystems per year. This is likely to drive ecological tipping points in which primary producers (plants and algae) flourish and out-compete dark-adapted communities. We demonstrate this principle on Antarctic shallow seabed ecosystems, which our data suggest are sensitive to small changes in the timing of sea-ice loss. Algae respond to light thresholds that are easily exceeded by a slight reduction in sea-ice duration. Earlier sea-ice loss is likely to cause extensive regime shifts in which endemic shallow-water invertebrate communities are replaced by algae, reducing coastal biodiversity and fundamentally changing ecosystem functioning. Modeling shows that recent changes in ice and snow cover have already transformed annual light budgets in large areas of the Arctic and Antarctic, and both aquatic and terrestrial ecosystems are likely to experience further significant change in light. The interaction between ice-loss and solar irradiance renders polar ecosystems acutely vulnerable to abrupt ecosystem change, as light-driven tipping points are readily breached by relatively slight shifts in the timing of snow and ice-loss.

Defense in shallow-water invertebrates at oceanic islands vs. the mainland coast

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 15:159-166 (2012) - DOI: https://doi.org/10.3354/ab00411 Defense in shallow-water invertebrates at oceanic islands vs. the mainland coast João Filipe da Cruz1,*, Gonçalo Calado1,2 1Faculdade de Ciências Biomédicas, Universidade Lusófona de Humanidades e Tecnologias, Campo Grande, 1749-024 Lisboa, Portugal 2IMAR, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal *Email: joaofilipecruz@gmail.com ABSTRACT: Islands are often considered natural laboratories and thus excellent models for testing theories on adaptive radiation. To date, most studies have focused on terrestrial ecosystems. In a comparative study between island populations and their mainland counterparts, Vermeij (2004, Frontiers of biogeography, p 239−254), using published data, argued that shallow-water marine shelled molluscs are better defended against predation along continents than on oceanic islands, possibly due to a lower predation pressure on islands. Here we evaluate this hypothesis, using shallow-water marine gastropods from the Azores and the Portuguese mainland as models (the island species Columbella adansoni and the mainland species C. rustica, and populations of Stramonita haemastoma from both study areas). Pleistocene S. haemastoma fossils from the Azores were also analyzed. Specimens were measured for defense-related shell characteristics and compared (island vs. mainland populations) using principal component analysis and Mann-Whitney tests. The results revealed that Azorean C. adansoni possess significantly thicker and wider shells with a narrower aperture than mainland C. rustica, which present a lighter shell and a higher spire. Comparisons of island and mainland S. haemastoma indicate that the Azorean population is lighter, with a wider aperture, thicker lip, and lower spire. The comparison of Azorean S. haemastoma fossils and extant specimens showed significantly narrower apertures and thicker lips in Pleistocene shells. Despite some evidence supporting the arguments used by Vermeij, our analysis failed to conclusively support this hypothesis as a whole. KEY WORDS: Evolution on islands · Predatory impact · Island biogeography · Columbella adansoni · Columbella rustica · Stramonita haemastoma Full text in pdf format PreviousNextCite this article as: da Cruz JF, Calado G (2012) Defense in shallow-water invertebrates at oceanic islands vs. the mainland coast. Aquat Biol 15:159-166. https://doi.org/10.3354/ab00411 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 15, No. 2. Online publication date: May 15, 2012 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2012 Inter-Research.

First detection of thiotrophic symbiont phylotypes in the pelagic marine environment

Marine oligochaete and nematode thiotrophic symbionts (MONTS) form a phylogenetic cluster within the Gammaproteobacteria. For the symbionts that live on the nematode surface, environmental transmission is likely. However, until now, no free-living relatives have been found. In this study, we detected MONTS cluster members in offshore surface seawater of both the Caribbean and the Mediterranean Sea by PCR amplification of their 16S rRNA genes. This is the first evidence of members of this cluster in the pelagic environment. These may either be free-living forms of the symbionts or closely related, nonsymbiotic strains. In either case, their existence sheds light on the evolution of beneficial symbioses between shallow water invertebrates and sulfur-oxidizing bacteria.

Habitat conversion and species loss alters the composition of carbon sources to benthic communities

Generalist fishes provide an effective measure of the composition of basal carbon source pools fueling benthic communities, by integrating inputs across major consumer groups. In Doubtful Sound, New Zealand, shallow water invertebrate communities differ from those in other areas in Fiordland due to low salinity caused by freshwater output of a hydroelectric power station. To inves- tigate whether the composition of basal carbon sources supporting this benthic community differed from that in unaltered sites, we sampled a generalist wrasse, Notolabrus celidotus, from altered and unaltered habitats throughout Fiordland, and quantified its δ 13 C, δ 15 N, δ 34 S and the abundance of its fatty acids. N. celidotus from the altered sites in Doubtful Sound had significantly lower δ 13 C, δ 15 N and δ 34 S than those collected from similar habitats throughout the Fiordland region, indicating a higher proportion of chemosynthetically fixed organic matter for Doubtful Sound N. celidotus and the invertebrate community upon which they feed. Relatively high abundances of cis-vaccenic acid (18:1ω7c) in fish from Doubtful Sound and δ 13 C values that were ~-33‰ for 18:1 isomers confirmed the incorporation of chemosynthetic bacteria, and indicated that the original source of carbon was forest litter. Despite these differences in carbon supply to N. celidotus, analysis of otolith sections revealed no differences in growth rates among sites. The results of this study demonstrate that a shift in invertebrate composition can be indicated by higher order consumers. In Doubtful Sound, decreased abundance of filter-feeding bivalves has reduced the flux of marine derived carbon through the benthic community to higher trophic levels relative to more pristine sites in Fiordland.

Behavioural and respiratory response of the shallow-water hermit crab Pagurus cuanensis to hydrostatic pressure and temperature

The evolutionary history of the Anomura has long been controversially discussed. One aspect that has received little attention is the dissimilarity in physiological tolerances of the related families Paguridae and Lithodidae to environmental conditions, and how this may have determined the divergence and radiation of the families into different distribution ranges, in particular with regard to the limited penetration of the deep sea by the Paguridae. This study investigates the physiological tolerances of the temperate shallow-water hermit crab, Pagurus cuanensis, to various temperature (5, 10, 15, 20 °C) and pressure regimes (1 to 100 atm) by measuring the standard metabolic rate (SMR) and behavioural changes. SMR was primarily affected by temperature, with a notably low rate at 5 °C throughout all pressures. Behaviour was affected by pressure, with an increase in pressure from 50 to 100 atmospheres (atm) resulting in reduced activity. It is suggested that this species can tolerate hydrostatic pressures greater than those found in its natural bathymetric range. It is discussed that a lack of physiological cold tolerance and ecological factors, such as the need to find gastropod shells for protection, are the principal restrictions maintaining P. cuanensis to a maximum depth of approximately 250 m. We hypothesize that temperate shallow-water invertebrates could indeed be able to penetrate greater depths as continental shelf waters warm up in the course of global climate change.

Sea Slug Inks Its Way to Safety

SOCIETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY MEETING > SOCIETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY MEETING, 4–8 JANUARY, ORLANDO, FLORIDA Like squid and octopi, the shallow-water invertebrates known as sea hares eject ink when startled. Quick-moving squid and octopi use their inky clouds as a smokescreen, distracting potential predators while they attempt to escape. Now Charles Derby, a neuroethologist at Georgia State University in Atlanta, is discovering that the slow-moving sea hare's ink contains a host of protective compounds, some tailored to deter or confuse specific enemies. ![Figure][1] Magic potion. The ink released by sea hares is full of chemicals that drive predators away—and sometimes into a feeding frenzy. CREDIT: GENEVIEVE ANDERSON By testing the chemical makeup of inks secreted by two sea hare species facing different predators, Derby and his colleagues have found a complex defense system of deterrents, alarm calls, and feeding stimulants within the milky purplish and pink fluid. “The ink mixture allows the sea slug to persist in the presence of multiple predators through a simultaneous array of surprising mechanisms,” says Erik Sotka, a marine ecologist at the College of Charleston, South Carolina, Grice Marine Laboratory. Although researchers have long studied chemical defenses in the sea hare's skin and digestive glands, they have not looked in depth at the ink, says Derby. Sea hare “ink” actually consists of two substances, each secreted by a different organ into the mantle cavity, where they intermingle before being ejected. The ink is colorful and thin, whereas the other substance, opaline, is viscous. Each contains its own repertoire of compounds, and Derby finds that when ink and opaline meet, innocuous enzymes and amino acids react to form noxious substances. “This animal uses ‘common’ biological chemicals in novel ways,” notes Esther Leise, a marine biologist at the University of North Carolina, Greensboro. At the meeting, Derby described how sea hares ward off giant sea anemones. An anemone's tentacles may snare a sea hare, but the predator immediately spits out the potential meal and vigorously retracts its tentacles once the hare ejects its inky weapon, Derby reported. His postdoc Cynthia Kicklighter has found that opaline alone has no repulsive effect: If anything, it stimulates feeding behavior by the anemone. But the ink contains all sorts of anemone-repulsing chemicals, says Derby. In contrast, when Derby, Kicklighter, and their colleagues tested opaline and ink separately against spiny lobsters, another sea hare predator, the opposite proved true: Opaline was more protective than the ink, they reported last year. The lobster work also suggests that feeding stimulation is actually a defensive strategy. The sea hare's ink-opaline mixture contains substances, such as the amino acid taurine, that set off a feeding frenzy in a lobster—it grabs at the ground and ink cloud as if to ingest it, enabling the sea hare to slink away. As an added bonus, the ink mixture spreads the word among sea hares when danger approaches. Kicklighter and her colleagues have recently presented either ink or opaline to juvenile sea hares. The animals drew in their heads and moved away from either substance. The sea hares did the same when exposed to ink from an octopus and a squid, suggesting a common warning system for all these species. The researchers have identified three of the sea hare's warning compounds, two of which also exist in the squid and octopus inks. Paul Moore, a sensory ecologist at Bowling Green State University in Ohio, calls the sea hare's arsenal “a case of deceptive chemical signaling strategy not seen before [in animals].” Such research “will open up a new avenue of thought for aquatic chemical ecology,” he predicts. [1]: pending:yes

Molecular phylogeny, evolutionary rates, and divergence timing of the symbiotic dinoflagellate genus Symbiodinium

Symbiotic dinoflagellates belonging to the genus Symbiodinium are found in association with a wide variety of shallow-water invertebrates and protists dwelling in tropical and subtropical coral-reef ecosystems. Molecular phylogeny of Symbiodinium, initially inferred using nuclear ribosomal genes, was recently confirmed by studies of chloroplastic and mitochondrial genes, but with limited taxon sampling and low resolution. Here, we present the first complete view of Symbiodinium phylogeny based on concatenated partial sequences of chloroplast 23S-rDNA (cp23S) and nuclear 28S-rDNA (nr28S) genes, including all known Symbiodinium lineages. Our data produced a well resolved phylogenetic tree and provide a strong statistical support for the eight distinctive clades (A–H) that form the major taxa of Symbiodinium. The relative-rate tests did not show particularly high differences between lineages and both analysed markers. However, maximum likelihood ratio tests rejected a global molecular clock. Therefore, we applied a relaxed molecular clock method to infer the divergence times of all extant lineages of Symbiodinium, calibrating its phylogenetic tree with the fossil record of soritid foraminifera. Our analysis suggests that Symbiodinium originated in early Eocene, and that the majority of extant lineages diversified since mid-Miocene, about 15 million years ago.

Seasonal temperature fluctuations in the high northern latitudes during the Cretaceous Period: isotopic evidence from Albian and Coniacian shallow-water invertebrates of the Talovka River Basin, Koryak Upland, Russian Far East

Palaeotemperatures during the Albian–Coniacian in the northernmost Pacific have been determined on the basis of oxygen isotopic analysis of well-preserved brachiopod and molluscan shells from the Koryak Upland, Far East Russia. Those obtained from the calcitic brachiopod shells from the Albian range from 12.5 to 22.7 °C. The lower temperature level corresponds to winter seasons and the higher reflects summer temperatures. Probable winter isotopic palaeotemperatures, fluctuating from 10.9 to about 14.1 °C, were obtained from Coniacian bivalve shells. Presumed spring and autumn isotopic palaeotemperatures for the Coniacian, fluctuating from 14.1 to 17.7 °C, were obtained from rhynchonellid brachiopods and bivalves, all with calcitic shells, and ammonoids with aragonitic shells. Presumed summer isotopic palaeotemperatures varied between 18.5 °C to 22.4 °C. The new and previously published data suggest a short-term presence of polar ice during the Cretaceous (early Maastrichtian) only in the Southern Hemisphere on the Antarctic continent. Evidence pertaining to the Northern Hemisphere seems to suggest only occasional short-lived subfreezing conditions. These most probably occurred during polar winters in the early Valanginian, late Coniacian–early Santonian and early Maastrichtian. Temperatures in northern high latitudes during the course of even these winter seasons were probably not low enough for the formation of permanent sea ice. This may be a result of the lack of a continental massif in the North Pole area and a significant ameliorating effect of oceanic heat-transport poleward through the straits of Turgai and the Western Interior of North America.

Two Genetically Distinct Populations of Bobtail Squid, Euprymna scolopes, Exist on the Island of O'ahu

Population structure of the endemic Hawaiian bobtail squid, Euprymna scolopes, was examined using both morphological and genetic data. Although allozyme polymorphism was negligible, measurements of eggs, juveniles, and adults, as well as genetic data sequences of mitochondrial cytochrome oxidase I, demonstrated highly significant population structuring between two populations found on the northeastern and southern coasts of the island of O'ahu. These data suggest that extremely low levels of gene flow occur among these populations. Population subdivision of marine shallow-water invertebrates in Hawai'i is not expected based on earlier surveys, but may reflect a more general pattern for organisms, both marine and terrestrial, that exhibit limited dispersal. The subdivision also provides insight into the pathway through which coevolution between E. scolopes and its internal symbiont, Vibrio fischeri, may proceed.

An exclusive contract: specificity in the Vibrio fischeri-Euprymna scolopes partnership.

In the threatening world of dog eat dog, or rather, fish eat fish, marine animals have adopted many strategies for protection against predators ([25][1]). The Hawaiian squid Euprymna scolopes is no exception. When startled, this small, shallow-water invertebrate rapidly swims away while releasing a

Odobenocetops peruvianus: una remarcable convergencia de adaptación alimentaria entre morsa y delfín

Odobenocetops peruvianus : a remarkable convergence of feeding adaptation between walrus and dolphin Abstract Odobenocetops peruvianus (early Pliocene, Southern Peru) is a bizarre cetacean that is convergent in its skull, general aspect and presumably feeding habits with the modern walrus, Odobenus rosmarus. Cranial specializations that are unique among cetaceans, include the loss of elongated cetacean rostrum, the development of large premaxillary alveolar processes housing tusks, an inferred strong upper lip, the forward migration of the nares and dorsal binocular vision. The structure of face and basicranium indicates that it is a delphinoid cetacean probably related to the Monodontidae (beluga and narwhal). Like the walrus, O. peruvianus probably used its tongue and upper lip jointly in extracting, the soft parts of bivalves and other shallow water invertebrates by suction.

Reproduction in marine invertebrates in “stable” environments: the deep sea model

Summary Studies over the last 15 years have revealed that deep-sea benthic megainvertebrates show a variety of reproductive patterns that are adapted to the deep-sea, an environment in which the fauna occurs at low densities and resources are sparse. In the NE Atlantic the majority of species reproduce year round whilst a limited number of species reproduce on a seasonal basis believed to be entrained by the deposition of surface derived organic material on the deep-sea bed. A third pattern of rapid growth and early reproduction is found in a limited number of species that utilize unpredictable and ephemeral resources in the deep sea. Examination of the fertilization and behavioural biology of species from the bathyal depths suggest some species enhance fertilization success by forming pairs during their breeding season. However, the same concentration of sperm, as seen in shallow water invertebrates, is required for successful fertilization. At least one deep-sea species of echinoid requires high pressur...