Marine Substrate Research Articles

IDENTIFICATION IN PORE WATERS OF RECYCLED SEDIMENT ORGANIC MATTER USING THE DUAL ISOTOPIC COMPOSITION OF CARBON (δ13C AND Δ14C): NEW DATA FROM THE CONTINENTAL SHELF INFLUENCED BY THE RHÔNE RIVER

ABSTRACTEstuaries and deltas are crucial zones to better understand the interactions between continents and oceans, and to characterize the mineralization and burial of different sources of organic matter (OM) and their effect on the carbon cycle. In the present study, we focus on the continental shelf of the northwest Mediterranean Sea near the Rhône river delta. Sediment cores were collected and pore waters were sampled at different depths at one station (Station E) located on this shelf. For each layer, measurements of dissolved inorganic carbon concentration (DIC) and its isotopic composition (δ13C and Δ14C) were conducted and a mixing model was applied to target the original signature of the mineralized OM. The calculated δ13C signature of the mineralized organic matter is in accordance with previous results with a δ13COM of marine origin that is not significantly impacted by the terrestrial particulate inputs from the river. The evolution with depth of Δ14C shows two different trends indicating two different Δ14C signatures for the mineralised OM. In the first 15 cm, the mineralized OM is modern with a Δ14COM = 100 ± 17‰ and corresponds to the OM produced during the nuclear period of the last 50 years. Deeper in the sediment, the result is very different with a depleted value Δ14COM = –172 ± 60‰ which corresponds to the pre-nuclear period. In these two cases, the marine substrate was under the influence of the local marine reservoir effect with more extreme Δ14C results. These differences can be largely explained by the influence of the river plume on the local marine DIC during these two periods.

Magnetic proxies of continental shelf sediments and their implication for the benthic zone and shrimp fishing activities

The San Jorge Gulf is an ecosystem of great economic importance in the southern hemisphere. It is a breeding and spawning area for various fish and crustacean species. In particular, the Pleoticus muelleri shrimp in different stages of its life cycle and the benthic system are linked. Therefore, in recent decades, it has been of interest for this shrimp resource to carry out interdisciplinary studies focused on the properties of the marine substrate. The concentration of single domain + multidomain magnetite, paramagnetic minerals, and organic matter of seabed sediments vary widely within a study area of about 60400 km2. Values of specific magnetic susceptibility (χ), anhysteretic ratio (χARM/χ), total organic carbon (TOC), and total nitrogen (TN) range between 18.3–323.1 × 10−8m3kg−1, 1.5–13.2, 0.14–1.58%, and 0.02–0.19%, respectively. The spatial correlations between TOC and TN with χ (ρK = −0.72 and −0.59, respectively) and χARM/χ (ρK = 0.90 and 0.71) for these seabed sediments provide good magnetic proxies, which can be determined readily and with low cost. The spatial distribution of geochemical variables and magnetic proxies shows well-delimited areas concerning coastal, inner gulf, eastern, and northeastern zones, which could benefit the management of shrimp resource.

Climatic and tectonic drivers shaped the tropical distribution of coral reefs

Today, warm-water coral reefs are limited to tropical-to-subtropical latitudes. These diverse ecosystems extended further poleward in the geological past, but the mechanisms driving these past distributions remain uncertain. Here, we test the role of climate and palaeogeography in shaping the distribution of coral reefs over geological timescales. To do so, we combine habitat suitability modelling, Earth System modelling and the ~247-million-year geological record of scleractinian coral reefs. A broader latitudinal distribution of climatically suitable habitat persisted throughout much of the Mesozoic–early Paleogene due to an expanded tropical belt and more equable distribution of shallow marine substrate. The earliest Cretaceous might be an exception, with reduced shallow marine substrate during a ‘cold-snap’ interval. Climatically suitable habitat area became increasingly skewed towards the tropics from the late Paleogene, likely steepening the latitudinal biodiversity gradient of reef-associated taxa. This was driven by global cooling and increases in tropical shallow marine substrate resulting from the tectonic evolution of the Indo-Australian Archipelago. Although our results suggest global warming might permit long-term poleward range expansions, coral reef ecosystems are unlikely to keep pace with the rapid rate of anthropogenic climate change.

Comprehensive marine substrate classification applied to Canada's Pacific shelf.

Maps of bottom type are essential to the management of marine resources and biodiversity because of their foundational role in characterizing species' habitats. They are also urgently needed as countries work to define marine protected areas. Current approaches are time consuming, focus largely on grain size, and tend to overlook shallow waters. Our random forest classification of almost 200,000 observations of bottom type is a timely alternative, providing maps of coastal substrate at a combination of resolution and extents not previously achieved. We correlated the observations with depth, depth-derivatives, and estimates of energy to predict marine substrate at 100 m resolution for Canada's Pacific shelf, a study area of over 135,000 km2. We built five regional models with the same data at 20 m resolution. In addition to standard tests of model fit, we used three independent data sets to test model predictions. We also tested for regional, depth, and resolution effects. We guided our analysis by asking: 1) does weighting for prevalence improve model predictions? 2) does model resolution influence model performance? And 3) is model performance influenced by depth? All our models fit the build data well with true skill statistic (TSS) scores ranging from 0.56 to 0.64. Weighting models with class prevalence improved fit and the correspondence with known spatial features. Class-based metrics showed differences across both resolutions and spatial regions, indicating non-stationarity across these spatial categories. Predictive power was lower (TSS from 0.10 to 0.36) based on independent data evaluation. Model performance was also a function of depth and resolution, illustrating the challenge of accurately representing heterogeneity. Our work shows the value of regional analyses to assessing model stationarity and how independent data evaluation and the use of error metrics can improve understanding of model performance and sampling bias.

Linking Habitat and Associated Abiotic Conditions to Predict Fish Hotspots Distribution Areas within La Paz Bay: Evaluating Marine Conservation Areas

Hotspots are priority marine or terrestrial areas with high biodiversity where delineation is essential for conservation, but equally important is their linkage to the environmental policies of the overall region. In this study, fish diversity presences were linked to abiotic conditions and different habitat types to reveal multi-species and hotspots models predicted by ecological niche modelling methods within the Bay of La Paz, Mexico (south of Gulf of California). The abiotically suitable areas for 217 fish species were identified based on historical (1975–2020) presence data sets and a set of environmental layers related to distances from mangroves and rocky shores habitats, marine substrate, and bottom geomorphology conditions. Hotspot model distribution was delineated from a multi-species model identifying areas with ≥60 species per hectare and was compared to the marine conservation areas such Balandra Protected Natural Area (BPNA), illustrating how these models can be applied to improve the local regulatory framework. The results indicate that (1) there is a need for the BPNA to be enlarged to capture more of the delineated hotspot areas, and thus an update to the management plan will be required, (2) new conservation areas either adjacent or outside of the established BPNA should be established, or (3) Ramsar sites or other priority areas should be subject to legal recognition and a management plan decreed so that these vital habitats and fish diversity can be better protected.

Hybrid event beds generated by erosional bulking of modern hyperpycnal flows on the Choshui River delta front, Taiwan Strait

AbstractHyperpycnal flows are important agents for transporting detrital sediments from rivers to oceans. Previous studies often assumed that the deposits of flood‐controlled delta fronts would be dominated by graded sand with common hummocky cross‐stratification. This study documents, for the first time, hybrid event beds and plumite deposits inside the succession of a modern delta front. This delta in the Taiwan Strait is fed by the Choshui River, which is considered a highly efficient sediment transport system with individual floods with extremely high suspended sediment concentrations. The deltaic event beds recorded in the core were interpreted as hyperpycnal flow‐generated hybrid event beds and turbidites triggered by hypopycnal flows. Accelerator Mass Spectrometry 14C dating, grain‐size analysis and measurements of stable isotopic composition of organic matter were conducted to delineate the depositional process of the recognized beds. The internal subdivisions of the hybrid event beds were differentiated mainly based on sedimentary textures, including cohesive mud content, sand content and sorting. The disorganized portion (division H3) appears internally chaotic and contains large rafted substrate clasts but also displays an upward increase in dispersed cohesive mud from 35% (division H3a) to 50% (division H3b). In contrast, massive H1 divisions are characterized by much lower cohesive mud of ca 8%. The vertical arrangement between depositional facies allows the discrimination of three hybrid event bed types. The stable carbon isotopic composition of the organic matter reveals that the cohesive mud in each division of the hybrid event beds was sourced from marine substrate, rather than supplied by the original hyperpycnal flows. Therefore, the hybrid event beds are generated by energetic hyperpycnal flows, which can delaminate the muddy sea‐floor and incorporate large quantities of substrate fragments. The bulking of erosional hyperpycnal turbulent flow forces flow transformation and generates a more cohesive flow with a turbulent, dense head and trailing bipartite debris flow. The occurrence of hybrid event beds in modern shallow delta front settings is also an important novelty, implying a high density of hyperpycnal flows at the mouth of sediment‐laden rivers as well as the crucial impact of substrate entrainment on the development of hybrid event beds.

Cryptic fish associated with different substrates in two coastal reef communities of Colima, Mexico

It has been established that cryptic fish (CF) contribute to keeping the equilibrium of marine environments, and are also potential indicators of the environment. In the present study, ecological evaluations of CF-associated with reef communities exposed to high or low anthropogenic pressure off the coast of Colima, Mexico (La Boquita-LB, and Carrizales Bay-CA, respectively) were carried out. During 2014 a total of 16 surveys were carried out during winter-spring (WS), and eight surveys were carried out in summer-fall (SF). Three CF surveys were carried out in each reef community, covering a 180 m 2 area; several ecological indices were calculated, and the benthic habitat was characterized. A total of 3,056 CF belonging to 23 species, 22 genera, and 15 families were recorded. The species Axoclinus lucillae , Acanthemblemaria macrospilus , Coralliozetus boehlkei , E kemblemaria myersi , and Hippocampus ingens represented new records for CA and LB. The physiographic and topographic characteristics of the marine substrate were factors that significantly influenced the occurrence of CF, especially those with reduced mobility. There was higher CF richness and diversity during the SF. The species A. macrospilus , C. boehlkei , and E. myersi , associated with rocky environments with high sponge and macroalgae cover, were identified as potential bioindicators of degradation of the benthic habitat. The species Cirrhitichtys oxycechalus , A. macrospilus , Coryphopterus urospilus , and Elacatinus punticulatus were associated with coralline, crystalline, and relatively unperturbed environments.

Towards a 'Sea-Level Sensitive' dynamic model: impact of island ontogeny and glacio-eustasy on global patterns of marine island biogeography.

A synthetic model is presented to enlarge the evolutionary framework of the General Dynamic Model (GDM) and the Glacial Sensitive Model (GSM) of oceanic island biogeography from the terrestrial to the marine realm. The proposed 'Sea-Level Sensitive' dynamic model (SLS) of marine island biogeography integrates historical and ecological biogeography with patterns of glacio-eustasy, merging concepts from areas as diverse as taxonomy, biogeography, marine biology, volcanology, sedimentology, stratigraphy, palaeontology, geochronology and geomorphology. Fundamental to the SLS model is the dynamic variation of the littoral area of volcanic oceanic islands (defined as the area between the intertidal and the 50-m isobath) in response to sea-level oscillations driven by glacial-interglacial cycles. The following questions are considered by means of this revision: (i) what was the impact of (global) glacio-eustatic sea-level oscillations, particularly those of the Pleistocene glacial-interglacial episodes, on the littoral marine fauna and flora of volcanic oceanic islands? (ii) What are the main factors that explain the present littoral marine biodiversity on volcanic oceanic islands? (iii) How can differences in historical and ecological biogeography be reconciled, from a marine point of view? These questions are addressed by compiling the bathymetry of 11 Atlantic archipelagos/islands to obtain quantitative data regarding changes in the littoral area based on Pleistocene sea-level oscillations, from 150 thousand years ago (ka) to the present. Within the framework of a model sensitive to changing sea levels, we discuss the principal factors affecting the geographical range of marine species; the relationships between modes of larval development, dispersal strategies and geographical range; the relationships between times of speciation, modes of larval development, ecological zonation and geographical range; the influence of sea-surface temperatures and latitude on littoral marine species diversity; the effect of eustatic sea-level changes and their impact on the littoral marine biota; island marine species-area relationships; and finally, the physical effects of island ontogeny and its associated submarine topography and marine substrate on littoral biota. Based on the SLS dynamic model, we offer a number of predictions for tropical, subtropical and temperate volcanic oceanic islands on how rates of immigration, colonization, in-situ speciation, local disappearance, and extinction interact and affect the marine biodiversity around islands during glacials and interglacials, thus allowing future testing of the theory.

Marine substrate response from the analysis of seismic attributes in CHIRP sub-bottom profiles

Abstract This paper presents an evaluation of the response of seismic reflection attributes in different types of marine substrate (rock, shallow gas, sediments) using seafloor samples for ground-truth statistical comparisons. The data analyzed include seismic reflection profiles collected using two CHIRP subbottom profilers (Edgetech Model 3100 SB-216S), with frequency ranging between 2 and 16 kHz, and a number (38) of sediment samples collected from the seafloor. The statistical method used to discriminate between different substratum responses was the non-parametric Kruskal-Wallis analysis, carried out in two steps: 1) comparison of Seismic Attributes between different marine substrates (unconsolidated sediments, rock and shallow gas); 2) comparison of Seismic Attributes between different sediment classes in seafloors characterized by unconsolidated sediments (subdivided according to sorting). These analyses suggest that amplitude-related attributes were effective in discriminating between sediment and gassy/rocky substratum, but did not differentiate between rocks and shallow gas. On the other hand, the Instantaneous Frequency attribute was effective in differentiating sediments, rocks and shallow gas, with sediment showing higher frequency range, rock an intermediate range, and shallow gas the lowest response. Regarding grain-size classes and sorting, statistical analysis discriminated between two distinct groups of samples, the SVFS (silt and very fine sand) and the SFMC (fine, medium and coarse sand) groups. Using a Spearman coefficient, it was found that the Instantaneous Amplitude was more efficient in distinguishing between the two groups. None of the attributes was able to distinguish between the closest grain size classes such as those of silt and very fine sand.

About the Cover

Next article FreeAbout the CoverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreCoverSerpulid fan worms are sessile polychaetes that live in excreted tubes in the marine substrate. From their heads they project specialized feeding tentacles, called radioles, into the water column. They protect these exposed radioles with unusual photosensors, or eyes, located on the tentacles themselves. These eyes function as shadow-detecting alarms that identify looming threats and trigger a rapid withdrawal of the radioles into the worm’s fortified tube. Pictured on the cover is the most elaborate example of radiolar eyes: those found on the tentacles of the Christmas tree worm Spirobranchus corniculatus (Grube, 1862) from the Great Barrier Reef in Australia. These oddly-shaped compound eyes (orange-colored region) are composed of over 1000 individual optical elements, called ocelli.On pages 39–57 of this issue, Michael Bok, Megan Porter, Harry ten Hove, Richard Smith, and Dan-Eric Nilsson examine the broad diversity of radiolar eyes throughout the serpulid family, from single, scattered ocelli to the sophisticated compound eyes of S. corniculatus. They report on the phototransduction cascade transcripts expressed in the eyes of S. corniculatus, including opsins that belong to a poorly understood clade typically found in the brains of some invertebrate phyla. Furthermore, they describe and compare the fine structure of the ciliary photoreceptors found in the radiolar eyes of five species of serpulids. The authors consider the functional and evolutionary implications of these unique photoreceptors among the serpulid family and within the broader context of animal eye evolution.Credits: Photo, © Michael Bok, Lund University, Sweden. Cover design: Jeannie Harrell, University of Chicago Press. Next article DetailsFiguresReferencesCited by The Biological Bulletin Volume 233, Number 1August 2017New Insights from Genetic Data Sets on the Function and Evolution of Visual Systems Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/696189 © 2017 by The University of Chicago. All rights reserved.PDF download Crossref reports no articles citing this article.

Methane at the NW of Weddell Sea, Antarctica

The presence of gaseous hydrocarbons (from methane to n-pentane) in the seabed sediments and the bubbling of methane may suggest the presence of gas accumulations in the substrate of the NW Weddell Sea, Antarctica. The release of methane from the frozen ocean substrate adjacent to Seymour Island would be linked to climate instability during Late Cenozoic, when vast areas of the Antarctic continental shelf were flooded during the marine transgression that occurred c. 18,000 years ago, after the Last Glacial Maximum (LGM). As the ice melted, the sea again occupied the regions which it had abandoned. As the transgression was relatively rapid, the sub-air relief was not destroyed but was submerged and the ground had frozen (permafrost) along with it. Thus, the heat flow from the sea to the marine substrate, now flooded, would have destabilized frozen gas accumulations, which were originally formed into terrestrial permafrost during the LGM, similarly to what would have happened in the Arctic.

Morphology and chemical composition relation of Rapana thomasiana shell sampled from the Romanian Coast of the Black Sea

Rapana thomasiana is a predatory gastropod and a successful invader, which is found in abundance in the Black Sea. The aim of this study is to determine whether there is a relationship between morphology and chemical composition of rapana shell and therefore if the maturation of R. thomasiana shells, quantified by morphological parameters, has influence on their mineralization level, assessed by chemical composition analysis. For this purpose, integer individuals of R. thomasiana were collected from Limanu, Midia Cape and Vadu-Corbu beaches and morphological parameters of shells, such as length (L), mass (m), thickness (th) were investigated using specific mathematical statistic methods. Characteristic features of rapana whelk were found according to the corresponding marine substrate. Age classification was done using Bhattacharya method which has divided R. thomasiana population within three to four age-groups. In order to determine if there are significant differences between age classes in terms of chemical composition, for each determined age-group a chemical analysis was conducted. In this respect, the mineral content and total organic carbon (TOC) determined, showed in general, statistically significant differences (p<0.025 and p>0.975) among Ca, Mg and organic C values for almost all age-classes. The statistical trend suggests a slight growth of the organic matter and a drop of mineral composition with age.

Demerara Rise, offshore Suriname: Magma-rich segment of the Central Atlantic Ocean, and conjugate to the Bahamas hot spot

The Demerara Rise is a prominent bathymetric feature that has been considered as a broad expression of shallow continental basement and used in conjunction with the Guinea Plateau as a pinning point for circum-Atlantic plate reconstructions. Previously, shallow-penetration, poorly imaged seismic data over the Demerara Rise were modeled with the lower sequences interpreted as continental crust at relatively shallow depths. However, new long-offset, deeply penetrating seismic data provide evidence that basement nearly or entirely comprises excessively thick volcanic strata (approximately 21 km). Seismic character and geometry, 2D gravity modeling, and volcanic margin analogs were used to identify unfaulted, convex-upward seaward dipping reflector (SDR) packages. These steeply dipping (approximately 20°) igneous successions are westwardly divergent, and occur as offlapping reflector sets in trains as long as 250 km. This rift-related volcanism now recognized at the Demerara Rise was probably conjugate to syn-rift volcanism in South Florida/Great Bahama Bank, and from this we have predicted a volcanic element for the Guinea Plateau. This volcanism could be linked to a Bahamas hot spot at the initial opening of the Central Atlantic. Six SDR packages have been interpreted below the Late Jurassic-Early Cretaceous carbonate section of the rise, indicating that the early volcanism produced a marine substrate upon which the subsequent carbonate bank section developed. We have inferred that this Early Cretaceous volcanic/carbonate margin continued into the Guinea Plateau of West Africa. The pre-Aptian section was inverted and peneplained with a strong angular unconformity prior to the Early Cretaceous opening of the Equatorial Atlantic seaway. The newly identified Central Atlantic volcanic margin of the Demerara Rise holds implications of a volcanic origin for its conjugate margins. We have confirmed a voluminous magma-rich opening of the southeastern Central Atlantic.

Sediment dynamics and heavy metal pollution history of the Cruhlig Lake (Danube Delta, Romania)

This is the first study reporting recent sedimentation rates data (e.g. the past 120–150 years) for the Cruhlig Lake situated in the Danube Delta. The aim of this study is to analyse the recent sedimentation rates using the 210Pb dating method and identifying the heavy metal pollutants and their variability in time. Five sediment cores were taken with a gravity corer and – after drying the sliced samples–physical parameters, organic material and inorganic carbon content were determined. The total 210Pb content was measured via 210Po by alpha spectrometry, while supported 210Pb was measured by 226Ra (trough short life 222Rn daughters) with HPGe detectors. Heavy metals were determined by ICP-MS; from the 64 measured elements, only exceeding values of Al, As, Cd, Co, Cs, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Ni, Pb and Zn are discussed. After applying the CRS model, ages and sedimentation rates were calculated. The average sedimentation rate of the Cruhlig Lake is 0.21 ± 0.02 g/cm2y, Minimum values (0.05 ± 0.003 g/cm2y) are registered along the eastern shoreline of the lake before 1913, while maximum values are recorded due to the flooding in 2006 in the western side (1.34 ± 0.12 g/cm2y). Recent sedimentation rates divide the lake into three areas: the secluded eastern near shore part (0.63 ± 0.07 g/cm2y), the centre of the lake (0.92 ± 0.05 g/cm2y) and the dynamic western area, where most sediment transport takes place (1.13 ± 0.01 g/cm2y). The sedimentation pattern proves this lake to be very sensitive to fluvial discharge fluctuations. The building of the Iron Gate dams (1972 and 1985) had a negative impact on the sedimentation decreasing it with 58.74%, while after 1989 these values grew 2.25 times. The lake received a quantity of sediment rich in heavy metals in 1992 ± 3 y, which settled mostly on the eastern part. Values for Cd, Co, Cr, Hg, Pb and Zn are up to five times higher in 1980 ± 5 y in the eastern part of the lake, while Cd, Co, Cr and Ni are twice as high as the values measured for the marine substrate. Values of As show increasing of up to 150% in 2006 ± 2 y throughout the whole surface of the lake.

Biodiversity of benthic macroinvertebrates on hard substrates in the Currais Marine Protected Area, in southern Brazil

Abstract This study describes the biodiversity of benthic invertebrates on hard substrates in the Currais Marine Protected Area (Currais MPA), in the state of Paraná. The benthic community was sampled during 2012 to 2015, in winter and summer, at two islands and four groups of artificial reefs (ARs). Samples were collected along shallow (2-4 m) and deep (6-8 m) transects at the islands and ~18 m transects at the ARs. We also searched the literature to review all published records of benthic invertebrates on hard substrates in the Currais MPA. We recorded 176 taxa in the phyla Annelida (class Polychaeta), Arthropoda (class Maxillopoda, order Sessilia), Bryozoa, Cnidaria, Chordata (class Ascidiacea), Echinodermata, Mollusca and Porifera, in 13 classes, 40 orders and 75 families. With these 102 new records, our list comprises 58% of all recorded species. Of these, 58 taxa were first records for the state of Paraná. This remarkable number of new records highlights that biodiversity studies are lacking in Paraná. Fifteen non-indigenous species and one endangered species, the sea star Coscinasterias tenuispina (Lamarck, 1816), are included. This is an important transitional area to monitor expansion or constriction of the latitudinal distributions of species, in the context of climate change, that may influence the geographical distribution of species (both native and invasive). This study is the first inventory of marine hard substrate habitats of the Currais MPA with a surprisingly diverse community.

Substrate adaptations of sessile benthic metazoans during the Cambrian radiation

AbstractMany marine benthic metazoans must stabilize themselves upon the seafloor for survival, and as a result their morphologies are controlled in part by local substrate conditions. The Agronomic Revolution (AR), spurred by increasing vertical bioturbation during the Ediacaran–Cambrian transition, permanently altered the nature of shallow marine substrate conditions and led to a major shift in adaptive strategies among benthic metazoans. These ecological and evolutionary changes, known as the Cambrian Substrate Revolution (CSR), are generally understood from observations of benthic metazoan fossils across the Ediacaran/Cambrian boundary, but the timing and geographic extent of this transition are less well known. This analysis attempts to constrain the temporal and spatial pattern of the AR and CSR by performing a global-scale paleoecological analysis of the adaptive strategies of benthic fauna living during the Cambrian. This analysis focused on Burgess Shale-type (BST) faunas because of their exceptional preservation, and was conducted through direct observation of fossil specimens, analysis of data compiled from the Paleobiology Database, and literature review. From these analyses, faunal groups are assigned a metric, the Substrate Adaptability Index (SAI), that relates the overall affinity the fauna demonstrates toward either Proterozoic-style (SAI=0) or Phanerozoic-style (SAI=1) substrate conditions. The results of this analysis demonstrate that most early and middle Cambrian faunas were mixtures of Phanerozoic- and Proterozoic-style adaptive strategists, suggesting that Proterozoic-style substrates were still influential in controlling adaptive strategies in marine environments until at least that time. This is further supported by ichnofabric analysis of many of these localities, where overall bioturbation levels are exceedingly low, indicating a lack of mixed-layer development and the prevalence of firm Proterozoic-style substrates well into the Cambrian.

Coastal plain forests in southern and southeastern Brazil: ecological drivers, floristic patterns and conservation status

Coastal Plain Forests (also called Restinga Forests), defined as forest formations that occur in the coastal plain on a recent marine substrate (Quaternary), are primarily distributed in southern and southeastern Brazil. The Coastal Plain Forests represent one of the faces of the Atlantic Forest biome and are one of the most susceptible to degradation, given the high human pressure in coastal plains. In this work, we reviewed nearly 200 studies addressing the flora and vegetation of Restinga Forests over 70 years, aiming to find knowledge gaps and discuss future directions for these ecosystems. We focused on describing the main ecological drivers of the forest, the flora’s origin, the forest phenological and reproductive patterns, and on discussing the challenges for the conservation of the Restinga Forests. We found that a relatively large body of knowledge on Restinga Forests was accumulated over the last decades. Studies on flora are relatively well distributed in the region, but some gaps are found in some stretches of coastline (in southern littoral) and for specific forest strata (understory and epiphytic, in southeastern littoral). A total of 1588 species were listed for Restinga Forests, including trees (754), epiphytes (253), lianas (165), herbs (185), shrubs (68), and others (163). Regarding the flora of the Restinga Forests, 40 % of the species are restricted to the Atlantic Forest region, while 60 % of the species are distributed in other Brazilian ecoregions. These ecosystems are characterized by lower tree diversity when compared to other Atlantic physiognomies; however, studies addressing the processes determining diversity patterns in different scales are still rare. The soil constraints (sandiness, high acidity, low nutrient content, and flooding) strongly limit tree growth but are apparently compensated by a rapid nutrient cycling in the ecosystem and varied morphological and physiological plant adaptations. These forests can be considered seasonal (in reproductive and vegetative phenophases) and apparently depend on animal interactions (seed dispersal). We also found that these systems are highly fragmented and that little attention has been given to ensure the maintenance of its diversity and processes. We suggest that initiatives to ensure integrated and long-term research policies directed toward biodiversity conservation are necessary for these ecosystems.

Colored ceramic foams with tailored pore size and surface functionalization used as spawning plates for fish breeding

The growing demand for reliable porous substrate materials for aquaculture of marine ornamental fishes (i.e. substrate spawners) requires a controllable processing in combination with a straightforward functionalization to adjust both, the material properties and the surface physico-chemical characteristics. In this study, highly porous ceramic foams made of alumina obtained by direct foaming are presented, which are conditioned for controlled aeration of egg clutches laid by clownfishes serving as model organisms for marine substrate spawners. Increasing stirring velocities during preparation of high alkane phase emulsified suspensions (HAPES) lead to decreased µm-scaled foam pore sizes, while similar high open porosities of around 80% are achieved. Wet-chemical silanization using hexadecyltrimethoxysilane (HDTMS) followed by subsequent oxygen plasma treatment of the foam surface is applied to generate bifunctionalized foams with hydrophobic matrix and hydrophilic surface properties. Under marine aquarium conditions, external aeration through the hydrophobic matrix of the foam is applied marginally below bubble point pressures resulting in a significant increase of the dissolved oxygen concentration of the surrounding water close to the foam surface without formation of undesired air bubbles. In accordance with increased foam pore sizes oxygen saturation rates of 0.26, 0.49 and 0.85%/min are obtained ensuring high oxygen concentrations at the spawning plate within a few hours. Assemblies of five bifunctionalized spawning plates to a ceramic housing are accepted by clownfish pairs, laying their eggs directly on the aerated ceramic substrate. The presented spawning plates are highly promising for sustainable aquaculture of marine ornamental fishes aiming to improve the survival rate of early life stages.

LOWER CAMBRIAN ANEMONE BURROWS FROM THE UPPER MEMBER OF THE WOOD CANYON FORMATION, DEATH VALLEY REGION, UNITED STATES: PALEOECOLOGICAL AND PALEOENVIRONMENTAL SIGNIFICANCE

Large (up to 7 cm in diameter) and deep-penetrating (up to 30 cm) vertical burrows are described from the lower Cambrian Wood Canyon Formation of the Death Valley region, United States, and their paleoenvironmental and paleoecological implications are addressed. Trace fossils occur as dense populations that precede the earliest occurrences of Skolithos pipe rock in the region. These trace fossils are assigned to the ichnogenera Bergaueria, Conichnus, and Dolopichnus, and each represents the burrowing behavior of an anemone-like organism. These ichnotaxa occur within oolitic and sandy dolostones of a flood-tidal delta and lagoonal environment, respectively, and burrow fill is dominated by echinoderm ossicles. Ichnofabric indices of 4–5 and a tidally influenced position place these ichnotaxa within the same nearshore locus of bioturbation as Skolithos pipe rock; however, unlike Skolithos pipe rock, the tracemaker of these trace fossils can be identified. This study reveals that anemone-like animals were responsible for extensive modification of the marine substrate and this style of deep-penetrating bioturbation appears first in nearshore environments. This is in accord with the observation that many evolutionary novelties originate in nearshore environments, and specifically that deep-penetrating bioturbation originated nearshore before expanding offshore. This study also provides insight into the paleoecology of earliest Cambrian noncalcified cnidarians and their behavior and paleoenvironmental distribution during the Cambrian radiation.

Radiometric dates of uplifted marine fauna in Greece: Implications for the interpretation of recent earthquake and tectonic histories using lithophagid dates

In AD 365 a great ( M w > 8) earthquake lifted up western Crete, exposing a shoreline encrusted by marine organisms, and up to 10 m of marine substrate beneath it. Radiocarbon ages determined for corals and bryozoans exposed between the paleo-shoreline and present sea level are consistent, within measurement error, with each other and with the date of the earthquake. But radiocarbon ages determined for the boring bivalve Lithophaga lithophaga found on the same substrate are at least 350 years, and up to 2000 years, older than the date of the earthquake that lifted them above sea level. These observations reveal two important effects that limit the use of radiocarbon lithophagid ages in tectonic and paleoseismological studies. The first is that the exceptional preservation potential of lithophagids allows them to remain intact and in situ long after natural death, while the substrate continues to be colonised until eventual uplift. The second, which we confirm with radiocarbon analysis of museum specimens of known age, is the incorporation of old ( 14C-free) carbon into lithophagid shells from the limestone host rock into which the lithophagids bored. The two effects are both significant in Crete and central Greece, and can cause the radiocarbon lithophagid ages to be up to 2000 years older than the uplift event which exposed them. Understanding these effects is important because lithophagids are far more abundantly preserved, and used to date uplift, than most other marine organisms. This study shows that they can rarely be used to distinguish uplift events, or date them to better than 1000 years, or even to distinguish whether observed uplift occurred in a single or in multiple events. After taking account of these uncertainties, the ages of the lithophagids are, however, consistent with the hypothesis that the highest prominent marine notches and exposed lithophagid holes within a few metres of sea level in Greece formed when sea level became relatively stable ~ 6000 years ago, following rapid rise after the last glacial maximum.