Ooids from Turkey and Egypt in the Eastern Mediterranean and a love-story of Antony and Cleopatra

Summary Cleopatra’s beach is one of the most famous in Turkey for its distinctive white sand, composed largely of ooids. Legend has it that the Roman leader, Mark Antony, had this sand shipped from Alexandria in Egypt to create a beach for his lower Cleopatra, on Sedir Island in G?kova Bay, SE Aegean Sea. This study examines the reality of this leagend from a comparison of the oolitic sand from Cleopatra’s beach in Turkey with oolitic sand from the coast west of Alexandria in Egypt, the home city of Cleopatra, and only place in the Mediterranea where Holocene ooids occur in abundance. The ooids on Cleopatra’s beach gave a pale browncreamy colour and dull surface texture. Most grains are spherical, with nuclei of terrigenous grains, peloids and bioclasts. The Cleopatra ooids have all the features typical of high-energy, shallow-marine ‘classic” ooids, but they occur in a very low energy bay and shown evidence of being out place there (microborings, discolouration, dull surface). In terms of size, shape, cortex fabric and mineralogy, the Cleopatra ooids show great similarities to those from the northern coast of Egypt, west of Alexandria. The Alexandria ooids examined have a white-cream colour with a high polish, although there are fewer silicate nuclei compared to the Cleopatra ooids. On the basis of textures and microfabrics, the hydrographic conditions at G?kova bay, the relatively small quantity of oolitic sand in this tiny pocket beach and the absence of this type of sand any-where else in Turkey, it is concluded that the oolitic sand was brought to Cleopatra’s beach from somewhere else, and that the northern Egyptian coast was the most likely source. This lends credence to the Antony and Cleopatra story. Calculations suggest that some 15 Roman corn barges would have been required to transport the quantity of sand now present on the beach in Turkey.     

Optimization of slow-release fertilizer dosage for bioremediation of oil-contaminated beach sediment in a tropical environment

The optimization of fertilizer concentrations for stimulating bioremediation in contaminated marine substrates is desirable for minimizing both cost and environmental risks associated with eutrophication. In this study, the effect of various dosages of the slow-release fertilizer, Osmocote, in stimulating an indigenous microbial biomass in oil-contaminated beach sediments was investigated. The Osmocote used comprises water-soluble N–P–K at concentrations of 18, 4.8, and 8.3% w/w respectively, and dosages tested were in the range of 0–4.0% dry weight equivalent of sediment. The beach sediments were taken from a tropical foreshore environment and spiked with an Arabian light crude oil (ALCO) to achieve a petroleum hydrocarbon content of 4.4% w/w. The experiment was conducted in open microcosms irrigated with seawater over a 42-day period. It was found that all Osmocote-dosed sediments had a sustained nutrient release for at least 42 days. An addition of 0 8% Osmocote to the sediments was sufficient to maximize metabolic activity of the biomass, and the biodegradation of straight-chain alkanes (C₁₀–C₃₃). An Osmocote dosage of 1.5% resulted in optimal biodegradation of more recalcitrant branched-chain alkanes (i.e. pristane, and phytane).     

Organic-rich bimineralic ooids record biological processes in Shark Bay,Western Australia

Marine ooids have formed in microbially colonized environments for billions of years, but the microbial contributions to mineral formation in ooids continue to be debated. Here we provide evidence of these contributions in ooids from Carbla Beach, Shark Bay, Western Australia. Dark 100–240 μm diameter ooids from Carbla Beach contain two different carbonate minerals. These ooids have 50–100 μm-diameter dark nuclei that contain aragonite, amorphous iron sulfide, detrital aluminosilicate grains and organic matter, and 10–20 μm-thick layers of high-Mg calcite that separate nuclei from aragonitic outer cortices. Raman spectroscopy indicates organic enrichments in the nuclei and high-Mg calcite layers. Synchrotron-based microfocused X-ray fluorescence mapping reveals high-Mg calcite layers and the presence of iron sulfides and detrital grains in the peloidal nuclei. Iron sulfide grains within the nuclei indicate past sulfate reduction in the presence of iron. The preservation of organic signals in and around high-Mg calcite layers and the absence of iron sulfide suggest that organics stabilized high-Mg calcite under less sulfidic conditions. Aragonitic cortices that surround the nuclei and Mg-calcite layers do not preserve microporosity, iron sulfide minerals nor organic enrichments, indicating growth under more oxidizing conditions. These morphological, compositional, and mineralogical signals of microbial processes in dark ooids from Shark Bay, Western Australia, record the formation of ooid nuclei and the accretion of magnesium-rich cortical layers in benthic, reducing, microbially colonized areas.     

Nest temperatures in a loggerhead nesting beach in Turkey is more determined by sea surface than air temperature

While climate change is now fully recognised as a reality, its impact on biodiversity is still not completely understood. To predict its impact, proxies coherent with the studied ecosystem or species are thus required. Marine turtles are threatened worldwide (though some populations are recovering) as they are particularly sensitive to temperature throughout their entire life cycle. This is especially true at the embryo stage when temperature affects both growth rates and sex determination. Nest temperature is thus of prime importance to understand the persistence of populations in the context of climate change. We analysed the nest temperature of 21 loggerheads (Caretta caretta) originating from Dalyan Beach in Turkey using day-lagged generalised mixed models with autocorrelation. Surprisingly, the selected model for nest temperature includes an effect for sea surface temperature 4-times higher than for air temperature. We also detected a very significant effect of metabolic heating during development compatible with what is already known about marine turtle nests. Our new methodology allows the prediction of marine turtle nest temperatures with good precision based on a combination of air temperature measured at beach level and sea surface temperature in front of the beach. These data are available in public databases for most of the beaches worldwide.     

Numerical classification of the coastal vegetation of Attu Island,Aleutian Islands,Alaska

Abstract. This phytosociological study of the beaches, dunes, and associated lower mountain slopes of Attu Island is the first effort to identify the major coastal vegetation types of the Aleutian Islands using numerical methods. It is the first attempt to use the relevé method in southern coastal Alaska and provides a basis for future comparison with other areas. 76 relevés represent the range of structural and compositional variation in the matrix of vegetation and landform zonation at 16 locations. Data are analyzed by multivariate methods using the MULVA-4 computer package and ordered with Wildi's numerical procedure to produce results similar to traditional phytosociological tabular classification. Nine major community types are distinguished in four physiognomic groups: 1. Dwarf-shrub mire: Vaccinium uliginosum-Empetrum nigrum; 2. Meadow: Athyrium filix-femina-Streptopus amplexifolius, Artemisia tilesii-Veratrum album, Elymus mollis-Montia (Claytonia) sibirica, Ligusticum scoticum-Elymus mollis; 3. Beach meadow: Elymus mollis-Senecio pseudo-arnica, Lathyrus maritimus-Elymus mollis; and 4. Beach: Mertensia maritima and Arenaria (Honckenya) peploides. These community types are described and interpreted in response to a complex, topographic gradient. Phytogeographic comparison of Attu Island with neighboring areas suggests close relationship to the beach and beach-meadow types of eastern Kamchatka and to the mesic meadows of the Alaskan Semidi Islands; there is a slightly lower relationship to the mesic meadows of nearby Buldir Island.     

Endogenous activity rhythm in Talitrus saltator,Britorchestia brito (Crustacea,Amphipoda) and Tylos europaeus (Crustacea,Isopoda) from Barkoukech Beach (Tabarka,Tunisia)

The locomotor activity rhythm of three supralittoral crustacean species, Tylos europaeus (terrestrial isopod) and Britorchestia brito and Talitrus saltator (amphipod, Talitridea), was investigated in Barkoukech Beach. The rhythm was monitored in individual animals in spring under continuous darkness and constant temperature. Results revealed that whatever the species, actograms and mean activity curves showed that specimens of T. europaeus and T. saltator concentrated their activity during the subjective night; whereas, B. brito concentrated its activity during the subjective day. The three species exhibited a circadian locomotor rhythm with mean circadian period, respectively, equal to 24h41′ ± 0h44′, 24h46′ ± 0h55′ and 25h21′ ± 1h16′. The most stable locomotor rhythm was found in T. saltator (0.444 ± 0.246). Furthermore, individuals of T. europaeus were significantly more active (10h47′ ± 2h52′) than the two amphipods. Differences in the activity patterns of the three species will be discussed as an adaptative strategy to respond to interspecific competitive interactions.     

Taphofacies analysis of recent shelly cheniers (beach ridges), northeastern baja california,Mexico

Summary This report presents the results of taphofacies analyses of shelly cheniers (mollusk-dominated lag-concentrations) from the tidal flats of northeastern Baja California, Mexico. The three generations of moderm (formed during last 70 years), submodem (younger than 1,500 BP), and subfossil (5,000–2,000 BP) cheniers can be distinguished by their position relative to the shoreline, their topography, and the radiocarbon-age of their shells. The generations differ in the duration and complexity of their taphonomic history. Sixty-one samples from nine localities were collected to test the utility of the taphofacies approach for studying chenier-type shell deposits. The three chenier generations, although all dominated by the bivalve molluskMulinia coloradoensis, differ significantly in their taxonomic composition due to taphonomic and/or biologic factors. The taphofacies analysis included 4,334 specimens ofM. coloradoensis described by nine taphonomic variables. Univariate analysis of those variables indicated that the shells that accumulated in the cheniers are little-affected by biological processes (bioerosion, encrustation), and moderately affected by physical processes (fragmetation, cracking, peeling, edge preservation). Only the luster features of shells (external luster, internal luster, and internal features) vary substantially and consistently with chenier age —a result of subaerial weathering. Multivariate taphofacies analysis discriminates the three generations of cheniers even when the poorly preservable luster variables are excluded from the analysis. This suggests that taphofacies discrimination is possible for fossil cheniers. The shells collected from the chenier surface have substantially poorer preservation than shells from the subsurface, indicating that taphonomic degradation in the chenier plain environment is a surface phenomenon. Chenier plain shelly assemblages are taphonomically distinct from assemblages formed in other marine environments: they have a very low frequency of macroscopically recognizable bioerosion and encrustation. The existence of preservable taphonomic differences between the cheniers that differ in their age (i.e., duration of preburial history), suggests that fossil lag concentrations may be useful in detecting incompleteness gradients along stratigraphic boundaries. A ‘taphonomic clock’—a correlation between a ‘time-sincedeath’ and shell preservation—was found only for luster features, taphonomic attributes that are unlikely to be preserved in the fossil record.     

Microclimate modelling of beach sand temperatures reveals high spatial and temporal variation at sea turtle rookeries

The continual development of ecological models and availability of high-resolution gridded climate surfaces have stimulated studies that link climate variables to functional traits of organisms. A primary constraint of these studies is the ability to reliably predict the microclimate that an organism experiences using macroscale climate inputs. This is particularly important in regions where access to empirical information is limited. Here, we contrast correlative models based on both ambient and sea surface temperatures to mechanistic modelling approaches to predict beach sand temperatures at depths relevant to sea turtle nesting. We show that mechanistic models are congruent with correlative models at predicting sand temperatures. We used these predictions to explore thermal variation across 46 mainland and island beaches that span the geographical range of sea turtle nesting in Western Australia. Using high resolution gridded climate surfaces and site-specific soil reflectance, we predict almost 9 °C variation in average annual temperatures between beaches, and nearly 10 °C variation in average temperatures during turtle nesting seasons. Validation of models demonstrated that predictions were typically within 2 °C of observations and, although most sites had high correlations (r² > 0.7), predictive capacity varied between sites. An advantage of the mechanistic model demonstrated here is that it can be used to explore the impacts of climate change on sea turtle nesting beach temperatures as, unlike correlative models, it can be forced with novel combinations of environmental variables.