Impacts of gastropods on epiphytic microalgae on the brown macroalga Himantothallus grandifolius

2019 ◽  
Vol 31 (2) ◽  
pp. 89-97 ◽  
Author(s):  
Charles D. Amsler ◽  
Margaret O. Amsler ◽  
Michelle D. Curtis ◽  
James B. McClintock ◽  
Bill J. Baker
Keyword(s):  
Relative Abundance ◽  
Field Observations ◽  
Western Antarctic Peninsula ◽  
Sea Star ◽  
Gastropod Species ◽  
Mutualistic Relationship ◽  
Hard Bottom Communities ◽  
Scale Experiment ◽  
Very High ◽  
Brown Macroalga

AbstractChemically defended benthic macroalgae that dominate shallow, hard bottom communities along the western Antarctic Peninsula support very high densities of mesograzers, particularly amphipods but also small gastropods. Previous studies have demonstrated that the macroalgae and amphipods form a mutualistic relationship. The chemically defended macroalgae provide the amphipods with a refuge from predation while the macroalgae benefit from the amphipods greatly reducing surface fouling by smaller algae. One of the three most important macroalgae in terms of overstory cover, Himantothallus grandifolius, forms huge blades that can carpet the benthos. Field observations suggest that gastropods may be higher in relative abundance in proportion to amphipods on H. grandifolius than on other overstory macroalgae. The present study documents the finding that natural abundances of gastropods on H. grandifolius maintained in mesocosms reduce fouling by microscopic algae, primarily diatoms. However, amphipods are probably also important in keeping the macroalga clean of diatoms in nature. In a smaller scale experiment, three gastropod species were differentially effective at reducing diatom coverage on H. grandifolius. The hypothesis that gastropods benefit from associating with H. grandifolius in potentially gaining a refuge from sea-star predation was also tested but not supported by the experimental results.

The neck flattening defensive behaviour in snakes: First record of hooding in the South American colubrid genus Philodryas

2015 ◽  
Vol 65 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Manuel Jara ◽  
Daniel Pincheira-Donoso
Keyword(s):  
Animal Species ◽  
First Record ◽  
Physical Contact ◽  
South American ◽  
Field Observations ◽  
Defensive Behaviour ◽  
Fitness Costs ◽  
Lateral Expansion ◽  
The South ◽  
Very High

Animal species have evolved a remarkable diversity of defensive phenotypic strategies aimed to deceive predators and other forms of danger. By relying on deception, these adaptations increase the chances of avoiding physical contact that may otherwise have very high fitness costs. One such deceptive behaviour is the popularly-known neck flattening, or “hooding”, observed in some snakes. Hooding consists in the lateral expansion and dorso-ventral flattening of the neck, which creates the impression of a bigger opponent during confrontations. This trait is highly characteristic of cobras (Elapidae family). However, neck flattening is not exclusive to elapids, and has in fact been observed in a few other snake lineages, including some species of the families Lamprophiidae and Colubridae. Here, we present the first report of hooding behaviour in the South American colubrid genus Philodryas, based on field observations conducted on the Chilean species P. chamissonis (the long-tailed snake). Our report adds to the few cases in which this deceptive behaviour has been observed in snakes outside the cobra family.

scholarly journals Quantitative assessment of actin transcript number in eggs, embryos, and tube feet of the sea star Pisaster ochraceus.

1985 ◽  
Vol 5 (11) ◽  
pp. 3001-3008 ◽  
Author(s):  
I Kovesdi ◽  
M J Smith
Keyword(s):  
Relative Abundance ◽  
Untranslated Region ◽  
Quantitative Assessment ◽  
Developmental Stages ◽  
Sea Star ◽  
Dot Blot ◽  
Pisaster Ochraceus ◽  
Hybridization Kinetic ◽  
Muscle Gene ◽  
Tube Feet

Actin coding sequence cDNA probes were used to quantitate the number of transcripts in RNA from eggs, embryos, and tube feet of the sea star Pisaster ochraceus. Transcript concentrations were measured in both total RNA and in poly(A)+ RNA by titration and hybridization kinetic methods. Surprisingly, the actin transcript number in sea star eggs is two orders of magnitude greater than in sea urchin eggs. There are at least 2.9 X 10(5) actin transcripts per sea star egg, 1.2 X 10(5) per 48-h gastrula and 1.9 X 10(5) per 72-h gastrula. The number of actin transcripts per unit mass of extracted tube foot RNA is lower than in developmental stages. The relative abundance and size of actin transcripts was determined by Northern and dot blot analyses using probes containing actin coding DNA or 3'-untranslated-region sequences. The actin transcript in eggs and embryos is 2,300 nucleotides (nt) long and originates from the Cy (cytoplasmic) gene class. In tube feet, the most abundant actin transcript is 2,200 nt long and originates from the M (muscle) gene class. Tube feet also contain, at lower abundance, 2,300-nt transcripts of the Cy gene type expressed in eggs and embryos.

scholarly journals Ketidakadilan Budaya Patriarkhi terhadap Perempuan di Nias

2019 ◽  
Vol 11 (1) ◽  
pp. 10
Author(s):  
Yurulina Gulo
Keyword(s):  
Social Construction ◽  
Analytical Approach ◽  
Qualitative Approach ◽  
Field Observations ◽  
Inductive Approach ◽  
Patriarchal Culture ◽  
The Social ◽  
Long Time ◽  
Very High ◽  
New View

The writing of this journal aims to give a new view of how a woman who in Ono Niha mythology has very high respect, but in reality the woman in Nias is the object of injustice in the culture of Patriarchy that has been formed for a long time in Nias. In this journal, using a descriptive-analytical approach with a qualitative approach. The qualitative approach emphasizes the accuracy of data, it will use an inductive approach, which means that data will be collected, approached, and abstracted through interviews, literature and field observations. Thus the authors obtain data that in Nias, women experienced oppression in a real patriarchal culture because of the social construction that made it number two and regarded as weak and low based on the nature of the natural label. The oppression experienced by women in society socially, politically and religiously. The basis of the injustice in society in various fields is rooted in the culture of patriarchy where men assume that women belong to their property, servants and complementaries.

scholarly journals Laboratory data on atomic spectra for extreme ultra-violet solar spectroscopy

1965 ◽  
Vol 23 ◽  
pp. 25-26 ◽  
Author(s):  
B. Edlén
Keyword(s):  
Relative Abundance ◽  
A Priori ◽  
Laboratory Data ◽  
Solar Spectrum ◽  
Ultra Violet ◽  
Laboratory Work ◽  
Atomic Systems ◽  
The Third ◽  
Order Of Magnitude ◽  
Very High

Expected relative prominence of elements and ionization stages is estimated from existing recordings of the solar XUV spectrum. The following 3 groups of elements, apart from H and He, need be considered : (C, N, O), (Ne, Mg, Si, Fe), (Na, Al, S, Ar, Ca, Ni), the relative abundance descending by approximately an order of magnitude from one group to the next, and all other elements being at least another order of magnitude less abundant. Lines of low and medium stages of ionization are expected only from most abundant elements. The observed presence in the solar spectrum of lines from the neon-like Fe XVII suggests that very high stages of ionization must not be a priori excluded.These considerations indicate that a discussion of laboratory data may be confined to atomic systems containing from 1 to 18 electrons. Observed data on these 18 isoelectronic sequences, and the possibilities of their extrapolation, are reviewed. It is concluded that required data for the first 10 sequences are well in hand, but considerable laboratory work remains to be done on the third-period sequences.A comprehensive paper is being prepared for later publication.

scholarly journals Heat transfer in volcano–ice interactions on Earth

2007 ◽  
Vol 45 ◽  
pp. 83-86 ◽  
Author(s):  
L. Wilson ◽  
J.W. Head
Keyword(s):  
Heat Transfer ◽  
Lava Flows ◽  
Linear Functions ◽  
Field Observations ◽  
Water Release ◽  
Glacial Ice ◽  
Water Ice ◽  
Ice Melt ◽  
Temperature Contrast ◽  
Very High

AbstractThe very high temperature contrast between magma/ lava and water ice commonly leads to the assumption that significant melting will take place immediately upon magma/ lava ice contact, yet observations of active flows show little evidence of voluminous melting upon contact. We use analytical thermal models to reassess the efficiency with which heat can be transferred from magma to ice in three situations: lava flows erupted on top of glacial ice, sill intrusions beneath glacial ice evolving into subglacial lava flows and dyke intrusions into the interiors of glaciers. We find that the maximum ratios of thickness of ice that can be melted to the thickness of magmatic heat source are likely to be ∽2–5 for subaerial lava flows encroaching onto glaciers, ∽6–7 for subglacial lava flows and ∽10 for dykes intruded into glacial ice. Rates of ice melt production are not linear functions of time and flow thickness, however, and this may account for the observations of minimal immediate water release from beneath advancing lava flows. Field observations during future eruptions should be directed at measuring the temperature of released water.

scholarly journals CORAL REEFS OF GORGONA ISLAND, COLOMBIA, WITH SPECIAL REFERENCE TO CORALLIVORES AND THEIR INFLUENCE ON COMMUNITY STRUCTURE AND REEF DEVELOPMENT

2016 ◽  
Vol 12 ◽  
Author(s):  
Peter W. Glynn ◽  
Henry Von Prahl ◽  
Felipe Guhl
Keyword(s):  
Community Structure ◽  
Coral Reefs ◽  
Relative Abundance ◽  
Eastern Pacific ◽  
Hermit Crabs ◽  
Leeward Side ◽  
Live Coral ◽  
Sea Star ◽  
Minimum Thickness ◽  
Coral Communities

This study offers an overview of the distribution and structure of coral reefs and coral communities at Gorgona Island, off the Pacific coast of Colombia. Biotic interactions, mainly the effects of corallivores, are examined and compared with coral communities elsewhere in the eastern Pacific in order to provide a basis for understanding regional differences in community structure. Located at the south end of the Panamá Bight and ca. 30 km offshore, Gorgona is largely removed from the influence of upwelling and freshwater dilution. The key corallivore Acanthaster, which is widely distributed in the tropical eastern Pacific, is absent from Gorgona, probably a result of unfavorable physical conditions (low temperatures and low salinites) for larval development in the Panamá Bight area. True fringing coral reefs are present at Gorgona and are best developed on the eastern or leeward side, but they also occur in one area on the western and exposed side of the island. The La Azufrada reef, the largest of the fringing reefs, was about 1 km long and 150 m wide, had a minimum thickness of 8 m and supported live corals to a depth of 15 m. Pocilloporid corals predominated on the reef crest and upper to mid forereef slope, and massive and small species increased in relative abundance in the deep forereef and sand plain zones. A corallivorous pufferfish and ovulid gastropod were abundant, but other known corallivores (e. g., Acanthaster, hermit crabs and Eucidaris) were either absent, uncommon or not feeding on live coral. Damage inflicted on live massive colonies by a damselfish, in order to "farm" algae, could play an important role in altering the relative abundances of corals in shallow reef zones. A comparison of coral reefs at Gorgona and Panamá, in areas with and without Acanthaster, show that nonpocilloporid corals, which are preferred prey items, have a higher relative abundance on reefs where the predatory sea star is absent.

scholarly journals Flash Flood Susceptibility Evaluation in Human-Affected Areas Using Geomorphological Methods—The Case of 9 August 2020, Euboea, Greece. A GIS-Based Approach

GeoHazards ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 366-382
Author(s):  
Anna Karkani ◽  
Niki Evelpidou ◽  
Maria Tzouxanioti ◽  
Alexandros Petropoulos ◽  
Nicoletta Santangelo ◽  
...  
Keyword(s):  
Debris Flows ◽  
Flash Flood ◽  
Flash Floods ◽  
Alluvial Fans ◽  
Field Observations ◽  
The Road ◽  
Flood Susceptibility ◽  
High Hazard ◽  
Flooding Events ◽  
Very High

Flash floods occur almost exclusively in small basins, and they are common in small Mediterranean catchments. They pose one of the most common natural disasters, as well as one of the most devastating. Such was the case of the recent flood in Euboea island, in Greece, in August 2020. A field survey was accomplished after the 2020 flash floods in order to record the main impacts of the event and identify the geomorphological and man-made causes. The flash flood susceptibility in the urbanized alluvial fans was further assessed using a Geographic Information System (GIS)-based approach. Our findings suggest that a large portion of the alluvial fans of Politika, Poros and Mantania streams are mainly characterized by high and very high hazard. In fact, ~27% of the alluvial fans of Politika and Poros streams are characterized with very high susceptibility, and ~54% of Psachna area. GIS results have been confirmed by field observations after the 2020 flash flood, with significant damages noted, such as debris flows and infrastructure damages, in buildings, bridges and the road networks. In addition, even though the adopted approach may be more time-consuming in comparison to purely computational methods, it has the potential of being more accurate as it combines field observations and the effect of past flooding events.

scholarly journals New instruments for geological photo-interpretation and mapping

1976 ◽  
Vol 80 ◽  
pp. 144-148
Author(s):  
K.S Dueholm
Keyword(s):  
Aerial Photography ◽  
Aerial Photographs ◽  
Topographic Maps ◽  
Topographic Mapping ◽  
Field Observations ◽  
Topographic Map ◽  
Photo Interpretation ◽  
New Instruments ◽  
Very High ◽  
Better Than

Aerial photography is now an integrated part of topographic mapping. Half a century ago photogrammetric methods revolutionised the production of topographic maps, mainly because all contour drawing and measuring of detaiIs were transferred from the field to the laboratory. Based on very few field observations, a detailed and very accurate topographic map can be drawn from aerial photographs by photogrammetric methods. Thus, for an area that would require many weeks of fieldwork to produce a satisfactory topographic map, the same result can be achieved in the photogrammetric laboratory in a single day. In addition, accuracy can be very high. For instance, for a map at the scaie 1:50000 an accuracy on the ground better than 0.5 m can be reached by photogrammetric methods.

Quantitative assessment of actin transcript number in eggs, embryos, and tube feet of the sea star Pisaster ochraceus

1985 ◽  
Vol 5 (11) ◽  
pp. 3001-3008
Author(s):  
I Kovesdi ◽  
M J Smith
Keyword(s):  
Relative Abundance ◽  
Untranslated Region ◽  
Quantitative Assessment ◽  
Developmental Stages ◽  
Sea Star ◽  
Dot Blot ◽  
Pisaster Ochraceus ◽  
Hybridization Kinetic ◽  
Muscle Gene ◽  
Tube Feet

Actin coding sequence cDNA probes were used to quantitate the number of transcripts in RNA from eggs, embryos, and tube feet of the sea star Pisaster ochraceus. Transcript concentrations were measured in both total RNA and in poly(A)+ RNA by titration and hybridization kinetic methods. Surprisingly, the actin transcript number in sea star eggs is two orders of magnitude greater than in sea urchin eggs. There are at least 2.9 X 10(5) actin transcripts per sea star egg, 1.2 X 10(5) per 48-h gastrula and 1.9 X 10(5) per 72-h gastrula. The number of actin transcripts per unit mass of extracted tube foot RNA is lower than in developmental stages. The relative abundance and size of actin transcripts was determined by Northern and dot blot analyses using probes containing actin coding DNA or 3'-untranslated-region sequences. The actin transcript in eggs and embryos is 2,300 nucleotides (nt) long and originates from the Cy (cytoplasmic) gene class. In tube feet, the most abundant actin transcript is 2,200 nt long and originates from the M (muscle) gene class. Tube feet also contain, at lower abundance, 2,300-nt transcripts of the Cy gene type expressed in eggs and embryos.

Behaviour and Feeding of the Nassariid GastropodCyclope Neritea, Abundant at Hydrothermal Brine Seeps off Milos (Aegean Sea)

1997 ◽  
Vol 77 (3) ◽  
pp. 753-771 ◽  
Author(s):  
A.J. Southward ◽  
E.C. Southward ◽  
P.R. Dando ◽  
J.A. Hughes ◽  
M.C. Kennicutt ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Interstitial Water ◽  
Aegean Sea ◽  
Fine Sand ◽  
Behaviour Pattern ◽  
Extreme Conditions ◽  
Field Observations ◽  
Elevated Salinity ◽  
Bacterial Mats ◽  
Very High

Field observations and laboratory experiments were made onCyclope neritea, a small (~10 mm diameter) burrowing stenoglossan gastropod with a flattened shell found in very high densities (>200 m2) in Paleohori Bay on the south coast of Milos (Aegean Sea).Cyclope neriteaforms a high proportion of the biomass at seeps in this bay, where the medium to fine sand overlies hot, sulphidic brines. About half the animals were found on the surface in the daytime, an exception to the normal habit of this species which usually emerges from the sediment only at night. TheC. neriteawere aggregated on the thinner bacterial mats over the seeps. In the laboratory,C. neritearemained active for 3 h at sulphide concentrations up to 1 mM, the highest concentration in the interstitial water in the upper 25 mm of sediment at the seeps. Although the species can tolerate elevated salinity and temperature, it shows little adaptation for sulphide detoxification by oxidative pathways. It may survive at the seeps by its behaviour pattern, especially the use of the extensible siphon to access oxic water above the sediment boundary layer, and perhaps by exclusion of sulphide from the tissues.Cyclope neriteaingests large quantities of sand together with adhering bacteria and diatoms, but also scavenges on other animals killed by the extreme conditions of the seeps.

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