Seasonality and lunar periodicity in the reproduction of Pocilloporid corals

Reproductive seasonality and lunar periodicity of planula release were investigated for the three brooding coralsPocillopora damicornis, Seriatopora hystrix, andStylophora pistillata at Heron Island in the southern Great Barrier Reef. Branch fragments collected from undisturbed colonies in the field were used to determine when planulae were present for all three species, and direct observations of planula release were made on colonies ofPocillopora kept in aquaria. All three species displayed marked seasonal variation in reproductive output, with nearly all reproductive activity occurring over the summer months.Pocillopora exhibited distinct lunar periodicity in planulation, with planula release occurring around three quarter moon, and no planulae being present in samples collected between new and full moons.Seriatopora also displayed lunar periodicity of planula release, although it was not as distinct as forPocillopora, whileStylophora did not show any lunar periodicity.     

Ecological and Biochemical Evaluation of the Environment of Modern Foraminifers of the White Sea

Current ecological conditions in the regions of Bol'shoi Keretskii raid and Glubokaya Salma (Kandalaksha Bay, White Sea) were evaluated on the basis of structural and dynamic indices of the upper sediments in the context of specific composition of the benthic foraminiferal community. The distribution of the main species of living foraminifers was determined for the shallow and deep-sea groups. The relationship between populations of the most abundant species of living benthic foraminifers and hydrolytic enzyme activities providing for destruction of bottom organic matter at biochemical rates has been revealed.     

Rubyspira, new genus and two new species of bone-eating deep-sea snails with ancient habits

Rubyspira, a new genus of deep-sea snails (Gastropoda: Abyssochrysoidea) with two living species, derives its nutrition from decomposing whalebones. Molecular phylogenetic and morphological evidence places the new genus in an exclusively deep-sea assemblage that includes several close relatives previously known as fossils associated with Cretaceous cold seeps, plesiosaur bones, and Eocene whalebones. The ability to exploit a variety of marine reducing environments may have contributed to the evolutionary longevity of this gastropod lineage.     

Muscle enzyme activities in a deep-sea squaloid shark, Centroscyllium fabricii, compared with its shallow-living relative, Squalus acanthias

The activities of several enzymes of energy metabolism were measured in the heart, red muscle, and white muscle of a deep and a shallow living squaloid shark, Centroscyllium fabricii and Squalus acanthias, respectively. The phylogenetic closeness of these species, combined with their active predatory nature, similar body form, and size makes them well matched for comparison. This is the first time such a comparison has been made involving a deep-sea elasmobranch. Enzyme activities were similar in the heart, but generally lower in the red muscle of C. fabricii. Paralleling the trend seen in deep-sea teleosts, the white muscle of C. fabricii had substantially lower activities of key glycolytic enzymes, pyruvate kinase and lactate dehydrogenase, relative to S. acanthias or other shallow living elasmobranchs. Unexpectedly, between the squaloid sharks examined, creatine phosphokinase activity was higher in all tissues of the deep living C. fabricii. Low white muscle glycolytic enzyme activities in the deep-sea species coupled with high creatine phosphokinase activity suggests that the capacity for short burst swimming is likely limited once creatine phosphate supplies have been exhausted.     

The Effects of Hydrostatic Pressure on Living Aquatic Organisms IV. Recovery and Pressure Experimentation on Deep-sea Animals

Capture of living deep-sea animals is reviewed. The conditions for the successful recovery of living animals from the deep-sea are elaborated with examples. Control of pressure, temperature, or both, appears to be a prerequisite for the capture of living deep-sea animals. Deep-sea animals (archibenthal) show a loss of the R₁ response in comparison with their shallow-water counterparts. Genuine deep-sea animals have now been recovered in a living state suitable for experimentation from the High Arctic.     

Deep-sea research ground for the study of living matter properties in extreme conditions

The Black Sea hollow bottom is a promising research ground in the field of deep-sea radiochemoecology and exobiology. It has turned out to be at the intersection of the earth and cosmic scientific interests such as deep-sea marine radiochemoecology from the perspective of the study of extreme biogeocenological properties of the Earth biosphere and exobiology from the standpoint of the study of life phenomena (living matter) outside the Earth biosphere, i.e. on other planets and during hypothetical transfer of spores in the outer space. The potential of this ground is substantiated with the data published by the author and co-workers on accumulation of 90Sr, 137Cs and Pu isotopes with silts of bathyal pelo-contour, on the quality of deep-sea hydrogen sulphide waters (after their contact with air) for vital functions of planktonic and benthic aerobes, as well as the species composition of marine, freshwater and terrestrial plants grown from the spores collected from the bottom sediments of the Black Sea bathyal. Discussion was based on V.I. Vernadsky's ideas about the living matter and biosphere, which allowed conclusions about the biospheric and outer space role of the described phenomena.     

Biodiversity of the deep-sea continental margin bordering the Gulf of Maine (NW Atlantic): relationships among sub-regions and to shelf systems

Background

In contrast to the well-studied continental shelf region of the Gulf of Maine, fundamental questions regarding the diversity, distribution, and abundance of species living in deep-sea habitats along the adjacent continental margin remain unanswered. Lack of such knowledge precludes a greater understanding of the Gulf of Maine ecosystem and limits development of alternatives for conservation and management.

Methodology/Principal Findings

We use data from the published literature, unpublished studies, museum records and online sources, to: (1) assess the current state of knowledge of species diversity in the deep-sea habitats adjacent to the Gulf of Maine (39–43°N, 63–71°W, 150–3000 m depth); (2) compare patterns of taxonomic diversity and distribution of megafaunal and macrofaunal species among six distinct sub-regions and to the continental shelf; and (3) estimate the amount of unknown diversity in the region. Known diversity for the deep-sea region is 1,671 species; most are narrowly distributed and known to occur within only one sub-region. The number of species varies by sub-region and is directly related to sampling effort occurring within each. Fishes, corals, decapod crustaceans, molluscs, and echinoderms are relatively well known, while most other taxonomic groups are poorly known. Taxonomic diversity decreases with increasing distance from the continental shelf and with changes in benthic topography. Low similarity in faunal composition suggests the deep-sea region harbours faunal communities distinct from those of the continental shelf. Non-parametric estimators of species richness suggest a minimum of 50% of the deep-sea species inventory remains to be discovered.

Conclusions/Significance

The current state of knowledge of biodiversity in this deep-sea region is rudimentary. Our ability to answer questions is hampered by a lack of sufficient data for many taxonomic groups, which is constrained by sampling biases, life-history characteristics of target species, and the lack of trained taxonomists.     

Climate influence on deep sea populations

Dynamics of biological processes on the deep-sea floor are traditionally thought to be controlled by vertical sinking of particles from the euphotic zone at a seasonal scale. However, little is known about the influence of lateral particle transport from continental margins to deep-sea ecosystems. To address this question, we report here how the formation of dense shelf waters and their subsequent downslope cascade, a climate induced phenomenon, affects the population of the deep-sea shrimp Aristeus antennatus. We found evidence that strong currents associated with intense cascading events correlates with the disappearance of this species from its fishing grounds, producing a temporary fishery collapse. Despite this initial negative effect, landings increase between 3 and 5 years after these major events, preceded by an increase of juveniles. The transport of particulate organic matter associated with cascading appears to enhance the recruitment of this deep-sea living resource, apparently mitigating the general trend of overexploitation. Because cascade of dense water from continental shelves is a global phenomenon, we anticipate that its influence on deep-sea ecosystems and fisheries worldwide should be larger than previously thought.     

Pressure and life: some biological strategies

All biological processes of life on Earth experience varying degrees of pressure. Aquatic organisms living in the deep-sea, as well as chondrocytic cells of articular cartilage are exposed to hydrostatic pressures that rise up to several hundred times that of atmospheric pressure. In the case of marine larvae that disperse through the oceanic water column, pressure changes might be responsible for stress conditions during development, limiting colonisation capabilities. In a number of biological systems, life strategies may be significantly influenced by pressure. In this review, we will focus on the consequences of pressure changes on various biological processes, and more specifically on animals living in the deep-sea. Revisiting general principles of pressure effects on biological systems, we present recent data illustrating the diversity of effects pressure may have at different levels in biological systems, with particular attention to effects on gene expression. After a review of the main pressure equipments available today for studying species living naturally at high pressure, we summarise what is known concerning pressure impact during animal development.     

Evolutionary history of anglerfishes (Teleostei: Lophiiformes): a mitogenomic perspective

Background  

The teleost order Lophiiformes, commonly known as the anglerfishes, contains a diverse array of marine fishes, ranging from benthic shallow-water dwellers to highly modified deep-sea midwater species. They comprise 321 living species placed in 68 genera, 18 families and 5 suborders, but approximately half of the species diversity is occupied by deep-sea ceratioids distributed among 11 families. The evolutionary origins of such remarkable habitat and species diversity, however, remain elusive because of the lack of fresh material for a majority of the deep-sea ceratioids and incompleteness of the fossil record across all of the Lophiiformes. To obtain a comprehensive picture of the phylogeny and evolutionary history of the anglerfishes, we assembled whole mitochondrial genome (mitogenome) sequences from 39 lophiiforms (33 newly determined during this study) representing all five suborders and 17 of the 18 families. Sequences of 77 higher teleosts including the 39 lophiiform sequences were unambiguously aligned and subjected to phylogenetic analysis and divergence time estimation.     

Reproductive cycles in tropical intertidal gastropods are timed around tidal amplitude cycles

Reproduction in iteroparous marine organisms is often timed with abiotic cycles and may follow lunar, tidal amplitude, or daily cycles. Among intertidal marine invertebrates, decapods are well known to time larval release to coincide with large amplitude nighttime tides, which minimizes the risk of predation. Such bimonthly cycles have been reported for few other intertidal invertebrates. We documented the reproduction of 6 gastropod species from Panama to determine whether they demonstrate reproductive cycles, whether these cycles follow a 2‐week cycle, and whether cycles are timed so that larval release occurs during large amplitude tides. Two of the species (Crepidula cf. marginalis and Nerita scabricosta) showed nonuniform reproduction, but without clear peaks in timing relative to tidal or lunar cycles. The other 4 species show clear peaks in reproduction occurring every 2 weeks. In 3 of these species (Cerithideopsis carlifornica var. valida, Littoraria variegata, and Natica chemnitzi), hatching occurred within 4 days of the maximum amplitude tides. Siphonaria palmata exhibit strong cycles, but reproduction occurred during the neap tides. Strong differences in the intensity of reproduction of Cerithideopsis carlifornica, and in particular, Littoraria variegata, between the larger and smaller spring tides of a lunar month indicate that these species time reproduction with the tidal amplitude cycle rather than the lunar cycle. For those species that reproduce during both the wet and dry seasons, we found that reproductive timing did not differ between seasons despite strong differences in temperature and precipitation. Overall, we found that most (4/6) species have strong reproductive cycles synchronized with the tidal amplitude cycle and that seasonal differences in abiotic factors do not alter these cycles.     

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 pressure for successful embryogenesis suggesting a depth-related segregation of deep-sea fauna. The origin of megafaunal populations of deep-sea invertebrates in the N. Atlantic is discussed in the light of these new data in relation to varying reproductive patterns and the environmental changes that have occurred during the last deglaciation.     

The red and the black: bioluminescence and the color of animals in the deep sea

The colors of deep-sea species are generally assumed to be cryptic,but it is not known how cryptic they are and under what conditions.This study measured the color of approximately 70 deep-sea species,both pelagic and benthic, and compared the results with twosets of predictions: 1) optimal crypsis under ambient light,2) optimal crypsis when viewed by bioluminescent "searchlights."The reflectances of the pelagic species at the blue-green wavelengthsimportant for deep-sea vision were far lower than the predictedreflectances for crypsis under ambient light and closer to thezero reflectance prediction for crypsis under searchlights.This suggests that bioluminescence is more important than ambientlight for the visual detection of pelagic species at mesopelagicdepths. The reflectances of the benthic species were highlyvariable and a relatively poor match to the substrates on whichthey were found. However, estimates of the contrast sensitivityof deep-sea visual systems suggest that even approximate matchesmay be sufficient for crypsis in visually complex benthic habitats.Body coloration was generally uniform, but many crabs had strikingpatterns that may serve to disrupt the outlines of their bodies.     

Comparative study on dihydrofolate reductases from <Emphasis Type="Italic">Shewanella</Emphasis> species living in deep-sea and ambient atmospheric-pressure environments

To examine whether dihydrofolate reductase (DHFR) from deep-sea bacteria has undergone molecular evolution to adapt to high-pressure environments, we cloned eight DHFRs from Shewanella species living in deep-sea and ambient atmospheric-pressure environments, and subsequently purified six proteins to compare their structures, stabilities, and functions. The DHFRs showed 74–90% identity in primary structure to DHFR from S. violacea, but only 55% identity to DHFR from Escherichia coli (ecDHFR). Far-ultraviolet circular dichroism and fluorescence spectra suggested that the secondary and tertiary structures of these DHFRs were similar. In addition, no significant differences were found in structural stability as monitored by urea-induced unfolding and the kinetic parameters, K _m and k _cat; although the DHFRs from Shewanella species were less stable and more active (2- to 4-fold increases in k _cat/K _m) than ecDHFR. Interestingly, the pressure effects on enzyme activity revealed that DHFRs from ambient-atmospheric species are not necessarily incompatible with high pressure, and DHFRs from deep-sea species are not necessarily tolerant of high pressure. These results suggest that the DHFR molecule itself has not evolved to adapt to high-pressure environments, but rather, those Shewanella species with enzymes capable of retaining functional activity under high pressure migrated into the deep-sea.     

Anaerobic Metazoans: No longer an oxymoron

The sediments of a deep-sea hypersaline and sulfidic Mediterranean basin have yielded an unexpected discovery, the first multicellular animals living entirely without oxygen. Reported by Danovaro et al. in BMC Biology, these three new species of Loricifera add a new and remarkable dimension to anoxic ecosystems previously thought to support only unicellular life.     

Molecular and functional adaptations in deep-sea hemoglobins

The past 20 years have witnessed the publication of numerous studies on hemoglobins (Hbs) from deep-sea animals. Most of the animals studied were collected at deep-sea hydrothermal vents and cold seeps, both being environments where the physical-chemical conditions may be severely challenging for metazoans. These environments may be characterized by deep, chronic hypoxia and high concentrations of toxic compounds such as sulfide and heavy metals. Many species from these environments express Hbs, even though they belong to taxa that otherwise were characterised by the absence of respiratory pigments. Hbs from vent and seep invertebrates commonly exhibit high affinities for oxygen when compared to related species from normoxic, shallow-water environments, and marked pH-dependence. These high affinities permit uptake of oxygen from hypoxic waters and the strong Bohr effects favor its release in the metabolizing acidic organs.     

The island rule and the evolution of body size in the deep sea

Aim  Our goal is to test the generality of the island rule – a graded trend from gigantism in small-bodied species to dwarfism in large-bodied species – in the deep sea, a non-insular but potentially analogous system.
Location  Shallow-water and deep-sea benthic habitats in the western Atlantic Ocean from the North to South Poles.
Methods  We conducted regression analyses of body size of deep-sea gastropods species relative to their shallow-water congeners using measurements from the Malacolog ver. 3.3.3 database.
Results  Our results indicate that, consistent with the island rule, gastropod genera with small-bodied, shallow-water species have significantly larger deep-sea representatives, while the opposite is true for genera that are large-bodied in shallow water. Bathymetric body size clines within the deep sea are also consistent with predictions based on the island rule.
Main conclusions  Like islands, the deep sea is characterized by low absolute food availability, leading us to hypothesize that the island rule is a result of selection on body size in a resource-constrained environment. The body size of deep-sea species tends to converge on an optimal size for their particular ecological strategy and habitat.     

珠江口及邻近海域大型底栖动物多样性随盐度、水深的变化趋势

利用2006年7-8月(夏季)、2007年4-5月(春季)和2007年10-12月(秋季)珠江丰水期、平水期和枯水期3个航次在南中国海北部珠江口附近海域4条由河口、近岸到深水区调查断面的数据, 研究大型底栖动物多样性由河口-近岸-深水的变化趋势及与环境因子的关系。春季、夏季和秋季分别获得大型底栖动物273、256和148种, 各季节均以环节动物种类最多, 节肢动物次之。大型底栖动物种类数、丰度、生物量和Shannon-Wiener多样性指数均由河口向近岸海域升高, 再由近岸向外海深水区降低。Pielou均匀度深水区最高, 其次为近岸。河口和深水区大型底栖动物k-优势度曲线位于近岸浅水域曲线之上, 表明生物多样性由河口向近岸升高, 而由近岸向深水则降低。大型底栖动物与环境因子Pearson相关性分析表明, 春、秋季大型底栖动物种类数、丰度和生物量与水深呈显著的负相关, 秋季种类多样性指数和均匀度也与水深呈显著的负相关性, 而夏季仅生物量与水深呈显著的负相关; 春、秋季大型底栖动物种类数、生物量、丰度、多样性指数和种类均匀度与盐度的相关性不显著, 但是夏季大型底栖动物种类数、丰度、多样性指数和种类均匀度与盐度呈显著正相关。单位面积(0.2 m²)内, 珠江口及邻近海域大型底栖动物在近岸浅水区较深水区和河口生物多样性高, 且生物量丰富。     

Enzyme sequence and its relationship to hyperbaric stability of artificial and natural fish lactate dehydrogenases

The cDNAs of lactate dehydrogenase b (LDH-b) from both deep-sea and shallow living fish species, Corphaenoides armatus and Gadus morhua respectively, have been isolated, sequenced and their encoded products overproduced as recombinant enzymes in E. coli. The proteins were characterised in terms of their kinetic and physical properties and their ability to withstand high pressures. Although the two proteins are very similar in terms of their primary structure, only 21 differences at the amino acid level exist between them, the enzyme from the deep-sea species has a significantly increased tolerance to pressure and a higher thermostability. It was possible to investigate whether the changes in the N-terminal or C-terminal regions played a greater role in barophilic adaptation by the construction of two chimeric enzymes by use of a common restriction site within the cDNAs. One of these hybrids was found to have even greater pressure stability than the recombinant enzyme from the deep-living fish species. It was possible to conclude that the major adaptive changes to pressure tolerance must be located in the N-terminal region of the protein. The types of changes that are found and their spatial location within the protein structure are discussed. An analysis of the kinetic parameters of the enzymes suggests that there is clearly a trade off between K(m) and k(cat) values, which likely reflects the necessity of the deep-sea enzyme to operate at low temperatures.     

The fossil viperfish Chauliodus testa sp. nov. (Stomiiformes: Stomiidae) from the Neogene of western Sakhalin,Russia

The first fossil viperfish from Russia is recorded. It comes from the Neogene of Sakhalin Island and is assigned to a new species, Chauliodus testa (Pisces: Stomiidae). The new species is most similar to living Ch. macouni and differs from it in the completely ossifying cervical centra, the fewer cervical vertebrae, and the short predorsal distance. The finding of deep-sea viperfishes in the Miocene of western Sakhalin is evidence of independent development of the ichthyofauna in the Neogene of the Tartar Strait and Sea of Japan.