Live Assemblages Research Articles

Shell strength of Eucallista purpurata (Bivalvia) from life and death assemblages on sandy beaches of the Bonaerense coast, southwest Atlantic Argentina

ABSTRACT Mollusc shells are among the most abundant and well-preserved organisms in sediments worldwide, but their shells are usually subject to fragmentation due to exposure time in the TAZ, which compromises their preservation potential. The shell strength of valves from life and death assemblages from the sandy beaches of Santa Clara (37°50′49″S, 57°30′16″W) and Mar Chiquita (37°44′45″S, 57°25′1.5″W) on the Bonaerense coast, southwest Atlantic Argentina, was analysed to capture the effect of taphonomic processes over time and to determine how intrinsic properties and taphonomic variables influence their shell strength. To achieve this, the mechanical resistance profile of the bivalve Eucallista purpurata was assessed using point load and microindentation tests, and the mineralogical composition and organic matter content of the shell, as well as morphological variables, were measured. We concluded that, as expected, shells from life assemblages were more resistant to compression than those from death assemblages, but surprisingly, right valves were more resistant to compression than left valves in both Mar Chiquita and Santa Clara death assemblages. No differences were observed between broken and unbroken shells.

Assemblages of well-being and belonging in young adults’ life-historical narrations: experiences from education and the labour market

ABSTRACT This article provides an empirical study of assemblages of well-being and belonging in the everyday lives of young adults. Using a discursive-narrative reading, I analyse how a sense of well-being and belonging emerge in the life assemblages of the research participants. The article is based on an ethnographically grounded longitudinal life-history study (2019 – ongoing) with six Finnish young adults. The analysis is based on the notion that all the interviewees seemed to have given up some education or work-related dreams they had in upper secondary school and that some of the assemblages they had previously viewed as suitable or desirable no longer seemed right. What emanated from the data were narrations about the search for a new situation in life in which the participants sensed well-being and belonging. The results of the data reading suggest that the overarching element of the assemblages is that they should enable the participants’ sense of well-being and belonging. This meant neither an individually governed success story nor a materialistically rich life for the participants but instead meant enabling a softer, more ‘my kind of’ everyday life that included important social relations and a suitable tempo and support at work.

The fossil insect assemblage associated with the Toarcian (Lower Jurassic) oceanic anoxic event from Alderton Hill, Gloucestershire, UK.

Extreme global warming and environmental changes associated with the Toarcian (Lower Jurassic) Oceanic Anoxic Event (T-OAE, ~183 Mya) profoundly impacted marine organisms and terrestrial plants. Despite the exceptionally elevated abundances of fossil insects from strata of this age, only assemblages from Germany and Luxembourg have been studied in detail. Here, we focus on the insect assemblage found in strata recording the T-OAE at Alderton Hill, Gloucestershire, UK, where <15% of specimens have previously been described. We located all known fossil insects (n = 370) from Alderton Hill, and used these to create the first comprehensive taxonomic and taphonomic analysis of the entire assemblage. We show that a diverse palaeoentomofaunal assemblage is preserved, comprising 12 orders, 21 families, 23 genera and 21 species. Fossil disarticulation is consistent with insect decay studies. The number of orders is comparable with present-day assemblages from similar latitudes (30°-40°N), including the Azores, and suggests that the palaeoentomofauna reflects a life assemblage. At Alderton, Hemiptera, Coleoptera and Orthoptera are the commonest (56.1%) orders. The high abundance of Hemiptera (22.1%) and Orthoptera (13.4%) indicates well-vegetated islands, while floral changes related to the T-OAE may be responsible for hemipteran diversification. Predatory insects are relatively abundant (~10% of the total assemblage) and we hypothesise that the co-occurrence of fish and insects within the T-OAE represents a jubilee-like event. The marginally higher proportion of sclerotised taxa compared to present-day insect assemblages possibly indicates adaptation to environmental conditions or taphonomic bias. The coeval palaeoentomofauna from Strawberry Bank, Somerset is less diverse (9 orders, 12 families, 6 genera, 3 species) and is taphonomically biased. The Alderton Hill palaeoentomofauna is interpreted to be the best-preserved and most representative insect assemblage from Toarcian strata in the UK. This study provides an essential first step towards understanding the likely influence of the T-OAE on insects.

Putting the dead to work: A new method to assess the autochthony of marine Ostracoda death assemblages

Sedimentary and paleontological records can be powerful means of reconstructing ecological and physical environmental changes, by using a variety of records extending proxies to extend chronologies beyond the reach of instrumental or manual records. Ostracods are often used as paleoenvironmental proxies. Estimating the population age structure could be a useful tool for assessing the influence of some environmental parameters on death assemblages and for determining the autochthoneity or allochthoneity of the species that make up the thanatocoenosis. In the literature, several methods based on population age structure have been proposed to distinguish autochthonous and allochthonous components of life/death ostracod assemblages.The Adult:Juveniles ratio analysis of a rich and well-preserved ostracod assemblage from one site in the circalittoral zone of Pontine Archipelago, in the central-eastern Tyrrhenian Sea, is presented. The new Specific Population Stage Index (SPS) is proposed, built upon the measurements of all growth stages in the assemblage. The population structure using the new SPS Index on three different grain sizes is tested against a list of putative in situ and transported ostracod specimens. The analysis on the small grain size (maximum heigth >63 µm) proved the most effective in describing the putative life ostracod assemblage, whereas in the largest grain size (maximum height >180 µm) the young instars of the smaller species are under-represented. This includes species generally under-represented in the fossil record of the Mediterranean, probably due to sample processing bias and not to the rarity of the species itself. Assessing the autochthoneity of modern/fossil assemblages has great potential for acquiring baseline information on ecosystems before the onset of human activities, making this an extremely powerful approach essential to evaluating anthropogenic impacts. This approach seeks to identify the in situ life assemblages within an ostracod population to ensure that paleoenvironmental interpretations are not biased by transported allochthonous elements.

Foraminiferal assemblages from the Abu Qir coastal area (Alexandria, Egypt): Wave-cut platform versus shallow-bay sediments

Benthic foraminifers living in euphotic coastal and shelf environments commonly occur in association with macrophytes (macroalgae and seagrasses), and many lineages have evolved morphologic adaptations to thrive in such habitats. Species that did not occur in the Mediterranean Sea prior to recent centuries, commonly known as “introduced” or “alien” species, are now widespread, and some are so abundant that they are altering coastal habitats. With accelerating climatic change and warming of Mediterranean surface waters, recognizing how invasive algal and foraminiferal species are affecting sedimentation and microenvironments has become increasingly urgent. This project examined 18 sets of sediment samples collected in the Abu Qir coastal area east of Alexandria for comparison with a previous assessment of live assemblages within the macroalgae. Overall, 68 foraminiferal species were identified, of which sixteen species were categorized as epiphytic. The hyaline epiphytic Elphidium crispum was the most common species found in sediments from the platform, while the porcelaneous free-living Quinqueloculina auberiana dominated sediments from the small bay. Eleven introduced foraminiferal species were recorded, one of which, Amphistegina lobifera, was commonly found, especially in the platform sediment samples. Taxa recorded live (stained) in platform sediments were predominantly (>10% each) Peneroplis, Amphistegina and Elphidium, while bay sediments were dominated by Quinqueloculina, followed in order by Elphidium, Amphistegina and Peneroplis. The assemblage differences from previously reported live assemblages associated with macralgae, compared with live and dead assemblages in sediments, appear to reflect hydrodynamic influence of sediment sorting and resistence of larger taxa to physical degradation.

Driving effects of land use and landscape pattern on different spontaneous plant life forms along urban river corridors in a fast-growing city

River corridors are critical in connecting fragmented greenspace and providing habitats for plants and animals. There is a paucity of information on the detailed influence of land use and landscape patterns on the richness and diversity of distinct life forms of urban spontaneous vegetation. This study aimed to identify the variables that dramatically affect spontaneous plants and then disentangle how to manage such a variety of land types to maximize the biodiversity-supporting function of urban river corridors. The total species richness was remarkably influenced by the amount of commercial, industrial, and waterbody area and the landscape complexity of water, green space, and unused land. In addition, the spontaneous plant assemblages of different life forms significantly differed in their responses to land use and landscape variables. Vines were more sensitive to urban sites, i.e., strongly negatively affected by residential and commercial areas but positively supported by green space and cropland. Multivariate regression trees indicated that the total plant assemblages were clustered most remarkably by the total industrial area, and the classified responding variables differed among distinct life forms. The colonizing habitat of spontaneous plants explained a high proportion of the variance and was also closely related to the surrounding land use and landscape pattern. These scale-specific interaction effects ultimately determined the variation in richness among various spontaneous plant assemblages in urban sites. Based on these results, in future city river planning and design, spontaneous vegetation could be protected and promoted by a nature-based solution according to their adaptability and preference for distinct landscape characteristics and habitat features.

Spatial and Temporal Distributions of Live Salt-Marsh Foraminifera in Southern New Jersey: Implications for Sea-Level Studies

ABSTRACT Geological reconstructions of relative sea-level change have been greatly enhanced by continuous high-resolution records with the use of salt-marsh foraminifera due to their relationship with tidal level in modern environments and subsequent preservation of tests in sediments. A detailed understanding of how live foraminifera assemblages compare to dead or total (live + dead) assemblages and the influence of environmental variables on foraminiferal distributions is essential for their use as a proxy to reconstruct sea level. Here, we evaluated small-scale spatial and temporal (seasonal and interannual) variability of live foraminifera assemblages from four high marsh monitoring stations along a salinity gradient in southern New Jersey over three years. In addition, we measured porewater and sedimentary variables and stable carbon isotopes during each sampling period every three months. In the 184 samples, we identified 11 live agglutinated foraminifera species and four distinct clusters of live foraminifera that correspond to the stations from which they were sampled and to the dead and total assemblages. We found no clear correlation over time between variability in live assemblages and measured environmental variables; however, elevation was the primary controlling factor influencing foraminiferal distributions, with secondary influences from salinity and substrate. The consistency of foraminiferal assemblages on spatial and temporal scales and among live, dead, and total assemblages further reinforces the value of salt-marsh foraminifera as reliable sea-level indicators.

High resolution spatiotemporal patterns of flow at the landscape scale in montane non‐perennial streams

AbstractIntermittent and ephemeral streams in dryland environments support diverse assemblages of aquatic and terrestrial life. Understanding when and where water flows provide insights into the availability of water, its response to external controlling factors, and potential sensitivity to climate change and a host of human activities. Knowledge regarding the timing of drying/wetting cycles can also be useful to map critical habitats for species and ecosystems that rely on these temporary water sources. However, identifying the locations and monitoring the timing of streamflow and channel sediment moisture remains a challenging endeavor. In this paper, we analyzed daily conductivity from 37 sensors distributed along 10 streams across an arid mountain front in Arizona (United States) to assess spatiotemporal patterns in flow permanence, defined as the timing and extent of water in streams. Conductivity sensors provide information on surface flow and sediment moisture, supporting a stream classification based on seasonal flow dynamics. Our results provide insight into flow responses to seasonal rainfall, highlighting stream reaches very reactive to rainfall versus those demonstrating more stable streamflow. The strength of stream responses to precipitation are explored in the context of surficial geology. In summary, conductivity data can be used to map potential stream habitat for water‐dependent species in both space and time, while also providing the basis upon which sensitivity to ongoing climate change can be evaluated.

UPPER CISURALIAN-LOWER GUADALUPIAN BRACHIOPODS FROM THE QARARI UNIT, BATAIN PLAIN, NORTHEAST OMAN: SYSTEMATICS, PALAEOECOLOGY AND CORRELATION

Permian brachiopods from Oman are well-known as valuable tools for correlation and palaeobiogeographical and palaeoclimatic reconstructions. Here, we describe a new brachiopod fauna from the Qarari Unit of the allochthonous Batain Group in northeast Oman. Brachiopods were collected from four localities: Wadi Khawr al Jaramah (WKJ), Jebel Qarari (JQ1), Jebel X (JX3) and Shiya (SH11). The age of the fossiliferous localities is wellconstrained to the late Kungurian-early Roadian by conodonts and fusulines, in agreement with the age suggested by the brachiopod ranges.The brachiopod fauna consists of 339 specimens belonging to 68 species of 8 orders, among which five species are here identified as new. Based on the taphonomic attributes and the analysis of the brachiopod life-styles, the assemblages from the Qarari Unit are interpreted as life assemblages thriving on varied substrates, with limited post-mortem exposure on the sea floor and rapid burial at depths around the storm wave base.Based on the generally high biodiversity indices (Shannon-Wiener and Margalef indices), the Qarari brachiopod fauna can be considered a biodiversity hotspot, only comparable, in term of biodiversity, to the coeval faunas from West Texas and South China. However, palaeobiogeographical affinities of the Qarari brachiopods with these faunas are scanty, as well as the affinities with coeval faunas from the northern Gondwana margin and the Cimmerian and Cathaysian blocks, except for some similarities with the upper Kungurian brachiopods of Myanmar. This may be explained by the fact that the Qarari succession was deposited in the Madagascan arm of Neo-Tethys, and thus rather isolated from the main Gondwanan margin.

Dendritické vrtby v miskách ramenonožců ze středního devonu (eifelu) pražské pánve (Barrandien, Česká republika)

Three ichnospecies of dendritic borings (Clionolithes cf. cervicornis, C. isp. A, and C. isp. B) were observed in abundant brachiopod shells in the Třebotov Formation (lowermost Eifelian, zone Polygnathus partitus) in two Prague localities (Praha-Holyně, “V rokli”, and Praha-Barrandov, street “K Barrandovu”). Borings are generally small-sized, of about 1 mm, but they can reach up to 4 mm. Borings are preserved inside thick translucent walls of brachiopods smooth shells (Trigonatrypa holynensis, Xenomartinia monoseptoides and Clorinda sp.). Borings are very frequent (almost in all examined shells), but never pass through a whole wall thickness of a brachiopod. Two or even more borings, commonly of a different type, are preserved on an individual shell. Both valves of articulated specimen may be bored, while the shell interior is devoid of borings neither shows any response to the boring activity such as uneven internal biomineralization. Majority of tunnels bores inside the shell wall, and the borings are opened by small irregular central pit. As more than a half of examined shells were infected, bioerosion likely had a negative impact on the shell preservation. Our study shows that the brachiopod infestation was selective. Only thick calcitic shells were bored, while thinner shells or exopunctate brachiopods (Holynatrypa, Peridalejina, Prokopia) were not a target of the borers. Similarly, crinoid and other echinoderm ossicles do not show any signs of a boring. A different dendritic boring referred to as Clionolithes radicans was observed on a shell of brachiopod coming from the Acanthopyge Limestone (Choteč Formation, Eifelian) from Zadní Kobyla locality near Koněprusy. The stellate trace is substantially larger (4.3 mm × 2.8 mm) than borings from the Třebotov Limestone, with deep and externally open canals. Borings from the Třebotov Limestone come from so-called “white beds”. These soft beds originated by weathering of a hard limestone, leaving loose generally small bioskeletal remains of echinoderms, gastropods, brachiopods, ostracods, dacryoconarids and other invertebrate groups. Dacryoconarid shells and crinoid ossicles dominate. The life assemblage occupied a deeper weakly hypoxic perireef environment below the fotic zone. The dendritic boring from the Acanthopyge Limestone comes from a completely different environment. Associated diverse and generally large brachiopods, fragmented fenestrate bryozoans and abraded tabulate and rugose corals (including Calceola sandalina) indicate a shallow-water highenergy reef environment. This is the first report of dendritic borings from the Eifelian of the Prague Basin. It confirms not only so far unknown presence of their borers in the area, but also reveals that their activity can be observed in the weakly lithified Devonian limestones in the area.

Between Aisthēsis and Colere: Sensoria, Everyday Improvisation and Ethnographic Reality

The individual experience of everyday city life is essentially an everyday improvisation among other people. It is in urban settings where socially structured formations of daily life meet purely individual situated experience in myriads of spontaneously created and shaped assemblages of everyday life. The visual perception of space, sonic orientation in a given place and olfactory plus tactile experience of the environment are the basic aesthetic performances in cultivating a common urban reality. The author discusses specificities of anthropological knowledge derived from first-hand experience of the life of other people in the field. To cope with the complexity of everyday urban improvisation, the author employs two ancient Greek terms to define the space of human interaction: aisthēsis, i.e., sensory perception, and the complex meaning of the Latin verb colere, from which the term culture is derived. The triangulation of everyday improvisation through the sensorial essence of everyday life complements the employment of two other ancient Greek terms, praxis and poiesis. The basic empirical materials used to discuss everyday improvisation in an urban environment are collected narrations of sensory perception and individual lives from sensobiographic walks in Ljubljana, Turku and Brighton. Historically, in the West, the dominance of the senses has shifted from sound, touch and smell, orienting people in orally designed cultural domains, to sight. Smelling is specific embeddedness in place. Its paradoxical position of sensing outside air deeply inside, integrated in breathing, but not always sensing anything special. At the crossroads of distant and close, inner and outer, olfactory experience is simultaneously existentially idiosyncratic and collectively shaped. The paper’s main point is that there are no clear limits between the experienced past and the present. However, both are aesthetically and culturally inscribed in specific registers of individual, social, cultural and embodied memories. The same stands for an ethnographic practice. Everyday life is a continuum of living, weaved together from many discontinuous contingencies. It consists of incongruent, incomplete and chaotic shifts. Repetitive social activities bring order into this everyday mess: rituals and work. For this reason, repetitive music is inevitable for establishing a common ground of the everyday. If ethnography ever touches reality, it is a continuous improvisation in everyday life, shared, collective, and peculiar individual improvisation.

New Species of Macroalgae from Tamengo Formation, Ediacaran, Brazil

The Tamengo Formation (Corumbá Group) is an important Ediacaran stratigraphic unit in South America due to the presence of metazoan fossils and geochemistry data of carbonate rocks, with excellent geochronological delimitation (between 555–541 Ma) obtained by U–Pb dating on volcanic zircons. The present work shows three new species of macroalgae found as carbonaceous compressions and studied for their morphology and taxonomy. All new taxa are characterized as centric macroalgae; Tamengophyton espinosa sp. nov. is a fan-shaped alga with striated thalli, dichotomous branches, trichomes with perpendicular growth, and a connecting membrane. Ladariella hidria sp. nov. is formed by a set of striated and branched thalli in a cylindrical form with almond-shaped structures in the top. Ladariophyton veinosa sp. nov. is characterized by the main growth thallus and an enlarged longitudinal structure at the center. These new occurrences of macroalgae add to the largest life assemblages in the Neoproterozoic of South America, which contributes to documentation of the evolutionary history of macroalgae and the paleoecological settings of the Late Ediacaran.

Living benthic foraminiferal assemblages of a transect in the Rockall Trough (NE Atlantic)

Foraminifera are unicellular protists and play a major role in the deep-sea ecosystems. This study focusses on the faunal analysis of living benthic foraminiferal assemblages and their vertical distribution along a transect in the Rockall Trough in the NE Atlantic. Therefore, seven multicorer cores from the Rockall Trough (RT-1 – RT-7), NE Atlantic, were collected at water depths between 1008 and 2205 m on the RRS Discovery cruise DY051 in spring 2016.Surface sediment samples of the collected material were analysed up to 10 cm sediment depth for living (Rose Bengal stained) benthic foraminifera to gain insight into the recent distribution of the foraminiferal fauna. The cores were sliced from 0 to 3 cm into 0.5 cm intervals and from 3 to 10 cm in 1 cm slices. Sediments were divided into the fractions >125 μm and 125–63 μm by wet-sieving. The analysis showed that stations differed in live assemblages, diversity, abundances and vertical distribution. Standing stock values of 92–168 ind./10 cm2 for the total, 54–130 ind./10 cm2 for the calcareous and 24–59 ind./10 cm2 for the agglutinated assemblages were obtained.Living deep-sea foraminiferal assemblages differed between the three shallower (RT-1 – RT-3) and the four deeper sites (RT-4 – RT-7), indicating that the different water masses could be a main factor controlling the deep-sea benthic fauna in the Rockall Trough. This area is characterised by two main water masses: the upper more saline Eastern North Atlantic Water (ENAW) and the lower North Atlantic Deep Water (NADW).Basically, Nonionella iridea occurred at all sites, while Cibicidoides species (except C. wuellerstorfi) and Melonis barleeanus were limited to water depths between 1008 and 1610 m (RT-1 – RT-3). Soft-shelled foraminifera increased sharply with water depth. Saccamminid sp. 1 contributed significantly to this increasing proportion of soft-shelled individuals with its maximum at 1857 m water depth (RT-5). Further characteristics of this transect include a mass occurrence of Uvigerina mediterranea, which was only present at 1008 m (site RT-1) or Globobulimina sp. 1 with its highest densities at 1610 m (RT-4), where it accounted for 20% of the total living foraminiferal fauna. The general microhabitat preferences where consistent with those of other studies, although the Rockall Trough is a very dynamic region considering food supply or other physical parameters.

Desiring occupation: Theorising the passion, creativity, and social production of everyday life

ABSTRACT In this paper, we operationalise a postmodern conceptualisation of desire in order to articulate occupation as a passionate, creative, and productive process that is entangled with the social world. Employing the philosophy of Gilles Deleuze and Felix Guattari, we use the concepts of assemblage and desire to theorise how passionate impulses are socially constructed and produce the flows of everyday life. The concept of assemblages refers to the dynamic webs of interconnection that make up our social world. The social and material elements within an assemblage (human, non-human, physical, non-physical) are continually shaping and being shaped by each other, entangled in an ongoing process of social production. In this paper, we theorise occupation as an assemblage, as a dynamic and social process that produces the flows of everyday life. The concept of desire refers to the creative impulse and passion that stirs individuals to create or act within their social world/assemblage. We present desire as a social force, one that is produced by the assemblages of everyday life and also one that produces everyday life. While the assemblages of everyday life have the potential to constrain desire, they also have the potential to creatively liberate the transformative potential of desire – generating liberating occupational flows.

Contributions of temporal and spatial variation to the diversity of soil-dwelling testate amoeba assemblages in a swampy forest

Understanding the spatial and temporal variation in protist communities is essential for comprehensive studies on diversity and biogeography, yet most research focuses on either spatial or temporal processes, ignoring their combined effects. Here we use an additive partitioning approach to estimate the contribution of temporal and spatial components to the total taxonomical (morphospecies) diversity of testate amoebae in a swampy forest (the forest-steppe zone, Russia) during a snow-free season (from April to November). Testate amoebae have been chosen as model organisms for the study because they are a diverse and abundant group of protists that play important roles in soil communities mostly as consumers in decomposer food webs. Our results indicate that seasonality considerably contributed to the variation in the total species richness (γ) of both live and empty shell assemblages of testate amoebae (48 and 38 %, respectively). The beta component of species richness related to the spatial variation among sampling plots explained 22 % of γ-diversity in live assemblages and 28 % in empty shell assemblages. Beta diversity (both as species richness and species composition) decreased towards the end of the snow-free season. Spring assemblages were dominated by hydrophilous species of testate amoebae, whereas xerophilic species were more abundant in autumn. Our results imply that the snowmelt phase could be an important factor setting the heterogeneity of testate amoeba assemblages in the early spring, whereas in the rest of snow-free season the assemblages were considerably controlled by substrate moisture. Overall, temporal sampling is essential for adequate estimates of species diversity of soil-dwelling testate amoebae.

Rapid assessment of coral cover from environmental DNA in Hawai'i

AbstractCoral reefs support the most diverse assemblages of marine life on Earth, yet are declining due to local and global stressors. Rapid and widespread monitoring is essential for tracking ecosystem responses, but assessment of coral communities traditionally relies on time‐consuming visual estimates of coral cover, the percentage of substrate occupied by living corals. The analysis of environmental DNA (eDNA) offers fast and efficient insights into the abundance and distribution of species, yet it remains untested to monitor coral biomass. Here, we demonstrate that visual estimates are highly correlated with the abundance of coral eDNA on reefs in Hawai'i measured with a relatively simple, rapid, but replicated PCR‐based metabarcoding approach. Target sequence length was also tested by amplifying short (~120 base‐pairs) and long (~400 base‐pairs) fragments from the same region of two mitochondrial DNA genes, 16S ribosomal DNA, and cytochrome oxidase‐1 using primers designed to preferentially amplify Hawaiian coral genera. Careful primer selection and target sequence lengths play an important role in determination of coral abundance from eDNA biomass. Given its broad applicability and ease of use, eDNA metabarcoding can provide complementary analytical support for biomonitoring programs and management initiatives tracking changes in coral cover caused by climate change and other disturbances on coral reefs.

South Devon, UK

Where can you teach the fundamental principles of geology in three short field days? In this feature article, I introduce South Devon as a classic area of geology, useful for introducing basic concepts relevant to school and first‐year degree curricula. That this region remains a catalyst for developing young geologists is especially fitting given that it was here that Henry de la Beche embarked on the first mapping project of what would later become the British Geological Survey. In South Devon, a novice geologist can learn about plate tectonics, the unifying theory of our subject, through a visit to two quarries. At Chipley Quarry, near Newton Abbott, sea‐floor spreading is well illustrated by Devonian pillow‐lavas extruded within the back‐arc margins of the Rheic Ocean. At Burrator Quarry, near Yelverton, the aftermath of continental collision is represented by the north‐verging Variscan fold belt, intruded and thermally metamorphosed by the Dartmoor granite. A trip along the coast to Paignton provides an informative lesson about the distinctive stratigraphic imprint that is created by this plate tectonic cycle. Here, tightly folded Devonian slates are unconformably overlain by near‐horizontal Permian breccia‐conglomerates at Waterside Cove. The ‘abyss of time’ at their junction represents the tens of millions of years involved in the uplift and denudation of Rheic Ocean sediments in the course of the Variscan Orogen. The Devonian and Permian successions of South Devon additionally serve as an excellent training ground for interpreting ancient environments with both marine and terrestrial facies spectacularly represented. Fossils abound in these strata, too, including the stromatoporoid life assemblage at Triangle Point, Torquay, where students have the opportunity to do a virtual scuba‐dive over a Devonian reef. Finally, given current discussions about employability in UK universities, there is even room in an excursion to instill the practical importance of geology: for example, a trip to the scenic Burrator Reservoir on Dartmoor reveals what can go wrong for geotechnical engineers when a major dam is sited on a granite weakened by chemical weathering. In summary, South Devon has it all—a brilliant natural laboratory for training and inspiring the next generation of geologists.

Distribution of Modern Salt-marsh Foraminifera from the Eastern Mississippi Sound, U.s.a.

AbstractThis study documented surface distributions of live and dead foraminiferal assemblages in the low-gradient tidal marshes of the barrier island and estuarine complex of the eastern Mississippi Sound (Grand Bay, Pascagoula River, Fowl River, Dauphin Island). A total of 71,833 specimens representing 38 species were identified from a gradient of different elevation zones across the study area. We identified five live assemblages and nine biofacies for the dead assemblages from estuarine, low marsh, middle marsh, high marsh, and upland transition environments. Although dissolution of calcareous tests was observed in the dead assemblages, characteristic species and abundance patterns dependent on elevation in the intertidal zone were similar between living assemblages and dead biofacies. The assemblages from the eastern Mississippi Sound estuaries were dominated by Ammonia tepida, Cribroelphidium poeyanum, C. excavatum, and Paratrochammina simplissima. The low marshes were dominated by Ammotium salsum, Ammobaculites exiguus, and Miliammina fusca. The dominant species in the middle marshes was Arenoparrella mexicana. The most abundant species in the high marshes was Entzia macrescens. The upland–marsh transition zones were dominated by Trochamminita irregularis and Pseudothurammina limnetis. Canonical correspondence analysis was applied to assess the relationship between a priori defined biofacies and measured environmental data (elevation, grain size, organic matter, and salinity) to test the hypothesis that distribution of foraminiferal assemblages is driven by elevation and hence flooding frequency. Salinity was the second most important explanatory variable of dead assemblages. Riverine freshwater from the Pascagoula River markedly influenced the live and dead assemblages in the Pascagoula River marsh, which was represented by low diversity and densities and dominance by Ammoastuta inepta. The relationship between the measured environmental variables and assemblage distributions can be used in future Mississippi Sound paleo-environmental studies.

Anamorphic development and extended parental care in a 520 million-year-old stem-group euarthropod from China

BackgroundExtended parental care is a complex reproductive strategy in which progenitors actively look after their offspring up to – or beyond – the first juvenile stage in order to maximize their fitness. Although the euarthropod fossil record has produced several examples of brood-care, the appearance of extended parental care within this phylum remains poorly constrained given the scarcity of developmental data for Palaeozoic stem-group representatives that would link juvenile and adult forms in an ontogenetic sequence.ResultsHere, we describe the post-embryonic growth of Fuxianhuia protensa from the early Cambrian Chengjiang Lagerstätte in South China. Our data demonstrate anamorphic post-embryonic development for F. protensa, in which new tergites were sequentially added from a posterior growth zone, the number of tergites varies from eight to 30. The growth of F. protensa is typified by the alternation between segment addition, followed by the depletion of the anteriormost abdominal segment into the thoracic region. The transformation of abdominal into thoracic tergite is demarcated by the development of laterally tergopleurae, and biramous walking legs. The new ontogeny data leads to the recognition of the rare Chengjiang euarthropod Pisinnocaris subconigera as a junior synonym of Fuxianhuia. Comparisons between different species of Fuxianhuia and with other genera within Fuxianhuiida suggest that heterochrony played a prominent role in the morphological diversification of fuxianhuiids. Functional analogy with the flexible trunk ontogeny of Cambrian and Silurian olenimorphic trilobites suggests an adaptation to sporadic low oxygen conditions in Chengjiang deposits for F. protensa. Finally, understanding the growth of F. protensa allows for the interpretation of an exceptional life assemblage consisting of a sexually mature adult alongside four ontogenetically coeval juveniles, which constitutes the oldest occurrence of extended parental care by prolonged cohabitation in the panarthropod fossil record.ConclusionsOur findings constitute the most detailed characterization of the post-embryonic development in a soft-bodied upper stem-group euarthropod available to date. The new ontogeny data illuminates the systematics, trunk segmentation and palaeoecology of F. protensa, offers insights on the macroevolutionary processes involved in the diversification of this clade, and contributes towards an improved understanding of complex post-embryonic reproductive ecology in Cambrian euarthropods.

Heterogeneity of environments in a coastal lagoon mouth by the comparison between living and dead benthic foraminiferal assemblages (Ria de Aveiro Portugal)

This study provides a comparison between living (LAs) and dead (DAs) assemblages of benthic foraminifera in 137 sites located at the mouth region of the Aveiro Lagoon (N Portugal). This coastal lagoon, commonly named Ria de Aveiro, is under strong anthropogenic influence due to changes in natural hydrodynamics through engineering structures and by the input of contaminants. The sedimentary environments of the mouth area are characterized by biotic (benthic foraminifera) and sedimentological (grain size, trace metals and total organic carbon concentrations) data. The pollution load index (PLI) identifies areas of increased concentrations of potentially toxic trace metals. An innovative combination of several statistical methods and extremely detailed data analyses allowed to verify that the dead associations (DAs) and the living assemblages (LAs) are absent or reduced in the deep and most hydrodynamically active zones along the navigable waterways of the channels. Breakwaters reducing the bottom currents allow the development of larger and more diversified LAs. The most suitable areas for LAs are located close to the South Jetty and in Mira Channel excluding the navigable channel and the eastern margin. LAs have in general little similarity with the DAs. Confined zones and areas with high organic matter flux and trace metals concentrations, where the sediments are being accumulated, are particularly unfavourable environments for living foraminifera. The obtained results evidenced that marked differences in hydrodynamics determine large dissimilarities between LAs and DAs. In some environments the taphonomic effects caused by the removal and high accumulation of foraminiferal tests can significantly misrepresent the faunal composition in the fossil registry, and lead to misinterpretations about the paleoenvironmental evolution.