The effect of flow speed and food size on the capture efficiency and feeding behaviour of the cold-water coral Lophelia pertusa

The capture efficiency and feeding behaviour of the cold-water coral (CWC) Lophelia pertusa (Linnaeus, 1758) were investigated considering: (1) different food types, (2) different food sizes and (3) different current speeds and temperatures. This study used two different multifactorial experimental approaches: (1) Corals were subjected to three different flow speeds (2, 5 and 10 cm s− 1) in 5 l volume tanks, and three different food types (alive zooplankton, alive algae, and dry particulate organic carbon) were offered to the corals under each current regime, analysing the capture rates of the corals under these different flow velocities. (2) In a flume, the feeding behaviour of the coral polyps was studied under different current speed regimes (1, 7, 15 and 27 cm s− 1) and a temperature change over a range of 8–12 °C. The obtained results confirm that low flow speeds (below 7 cm s− 1) appear optimal for a successful prey capture, and temperature did not have an effect on polyp expansion behaviour for L. pertusa. In conclusion, flow speeds clearly impact food capture efficiency in L. pertusa, with zooplankton predominantly captured prey at low flow velocities (2 cm s− 1) and phytoplankton captured at higher flow velocities of 5 cm s− 1. This split in capture efficiency may allow corals to exploit different food sources under different tidal and flow conditionsVersión del editor2,263

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

Evidence for pre-folding vein development in the Oligo-Miocene Asmari Formation in the Central Zagros Fold Belt, Iran

International audienceIn order to understand the interplay between vein development and folding in the carbonates of the Oligo-Miocene Asmari Formation (one of the main hydrocarbon reservoir rocks) in Iran, several anticlines have been investigated in the central part of the Zagros folded belt. Combining observations of relative chronology between veins based on calcite-filling phases and crosscutting/abutting relationships, as well as aerial/satellite image interpretation on several anticlines allowed proposing a tectonic model highlighting the widespread development of veins and other extensional micro/meso-structures in the Central Zagros folded belt. Our data suggest that most of the veins affecting the Asmari formation predated the main Miocene-Pliocene folding episode. An early regional vein set striking N50° marked the onset of collisional stress build-up in the region. Then, N150° and N20° trending vein sets were initiated in response to local extension caused by large-scale flexure/drape folds above N-S and N140° basement faults reactivated under the regional NE compression. At the onset and during Miocene-Pliocene folding of the sedimentary cover, the early formed veins were reactivated (reopened and/or sheared) while duplexes, low angle reverse faults and thrusts formed. Beyond regional implications, this study puts emphasis on the need of carefully considering regional/local vein development predating folding as well as influence of underlying basement faults in models of folded-fractured reservoirs in fold-thrust belts

Understanding crust formation during baking

Abstract A mathematical model of crust formation in bread baking is outlined, and used to explore the effect of the model parameters on crust thickness and density. Experimentation suggested that the interactions between model parameters were relatively weak, so it was possible to present the model results in terms of the percentage change in crust thickness from a 10% shift in each parameter. The results showed that crust thickness was particularly sensitive to the temperature at which bubbles collapsed and the doughÕs vapour pressure, but relatively insensitive to pre-oven dough conditions and dry crust properties. The overall mass in the crust showed similar dependencies, but with the addition that the thermal conductivity of the inner dough became significant

Using GIS Mapping of the Extent of Nearshore Rocky Reefs to Estimate the Abundance and Reproductive Output of Important Fishery Species

Kelp Bass (Paralabrax clathratus) and California Sheephead (Semicossyphus pulcher) are economically and ecologically valuable rocky reef fishes in southern California, making them likely indicator species for evaluating resource management actions. Multiple spatial datasets, aerial and satellite photography, underwater observations and expert judgment were used to produce a comprehensive map of nearshore natural rocky reef habitat for the Santa Monica Bay region (California, USA). It was then used to examine the relative contribution of individual reefs to a regional estimate of abundance and reproductive potential of the focal species. For the reefs surveyed for fishes (i.e. 18 out of the 22 in the region, comprising 82 % the natural rocky reef habitat,30 m depth, with a total area of 1850 ha), total abundance and annual egg productio

California Sheephead size structure at Little Dume and Rocky Point.

<p>California Sheephead (<i>Semicossyphus pulcher</i>) size structure (proportion of individuals per 5 cm size class) of females (white) and males (black) for Little Dume reef and Rocky Point reef. The legal minimum size limit (30 cm) for recreational fisheries is indicated by a black line.</p

Relationship between length and annual egg production for California Sheephead and Kelp Bass.

<p>Relationship between total length and annual egg production for individual California Sheephead (<i>Semicossyphus pulcher</i>) (solid line) and Kelp Bass (<i>Paralabrax clathratus</i>) (dashed line) calculated using sources in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030290#pone-0030290-t002" target="_blank">Table 2</a>.</p

Extent of nearshore rocky reefs in Santa Monica Bay, California.

<p>Extent of nearshore rocky reefs in Santa Monica Bay, California for (A) western Malibu, (B) eastern Malibu and (C) Palos Verdes Peninsula. The 30 m depth contour appears as a dotted line. Note that while some artificial reefs (for example sewer outfalls at Whites Point) and natural rock reef habitat extending below 30m are included here, they were not included in the area estimates (total extent of rocky reef habitat <30 m depth) in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030290#pone-0030290-t001" target="_blank">Table 1</a>.</p