Saturday, 26 May 2018

Fallacia californica: A new species of freshwater Diatom from California.

Diatoms are single celled algae related to Kelp and Water Moulds. They are encased in silica shells with two valves. During reproduction the cells divide in two, each of which retains one valve of the shell, growing a new opposing valve, which is slightly smaller and fits flush within the older valve. This means that the Diatoms grow smaller with each new generation, until they reach a minimum size, when they undergo a phase of sexual reproduction, giving rise to a new generation of full-sized cells. Members of the Order Naviculaceae are considered to be important environmental indicators, particularly in benthic freshwater habitats, as individual species tend to have very specific environmental requirements. The genus Fallacia are predominantly found in marine and brackish environments, particularly intertidal and estuarine mudflats. However they are also found in freshwater environments, with species known from Central Europe, Uruguay, Lake Baikal in Russia and California - a distribution which suggests that they may be more widespread, but as yet undiscovered in many areas.

In a paper published in the journal Phytotaxa on 23 March 2018, Rosalina Stancheva of the Department of Biological Sciences at the California State University San Marcos, and Kalina Manolyov of the Department of Biological and Environmental Sciences at Georgia College and State University, describe a new species of Fallacia from streams in California.

The new species is named Fallacia californica, in reference to the state where it was found. It was discovered in twenty one coastal streams in central and southern California and in Rock Creek located at the foothills of the Sierra Nevada Mountains. These Diatoms are elliptical, measuring approximately 4–5.6 μm wide and 6–14.5 μm long. They have rows of pores which run approximately parallel close to the centre, and radiate outwards towards the ends.

Fallacia californica from Aliso Creek, California, USA and from Soquel Creek (34), (37). (33), (35) Internal valve view. (34), (36)–(38) External valve view. (33) Areolae with remnants from thin hymens. (34), (37) Eroded valves with degraded conopeum show the canal of lyre shaped sternum. (35) Internal valve showing distinctly depressed lyre-shaped sternum. (36) Finger-like protrusions, each with two to four “pegs”, which fasten the connection of the conopeum and the mantle. (38) Girdle band. SEM images, scale bars 1 μm. Stancheva & Manolyov (2018).

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Bathers warned to be wary of Clinging Jellyfish in New Jersey.

The New Jersey Department of Environmental Protection has issued a warning to bathers in the Shrewsbury River in Monmouth County after researchers from Montclair State University found about 40 Clinging Jellyfish, Gonionemus vertens, during a survey of the river. These Cnidarians, which are the medusa stage of a Hydrozoan rather than a true Jellyfish, are found in Eelgrass and Seaweed beds in coastal and estuarine waters. and can produce a painful sting, mad worse by their tendency to cling to their victims and deliver repeated stings.

 A Clinging Jellyfish, Gonionemus vertens. Annette Govindarajan/Woods Hole Oceanographic Institution.

Clinging Jellyfish are native to the North Pacific, where they inhabit Seagrass beds around the Russian Far East and Sea of Japan, but were introduced to the northwest Atlantic in the 1890s.  They were thought to have disappeared by the 1930s as Eelgrass beds around the east coast of North America, where they had become established, died off. However, as efforts were made to restore these beds in the late twentieth century, the Jellyfish have re-appeared, and become a problem along parts of the coast between Connecticut and Maine. The Jellyfish were first observed sighted in New Jersey in 2016, and appear to be becoming established.

These 'Jellyfish' are the Medusa stage of a Olindid Hydrozoan; animals with a two-stage life history, alternating between a Jellyfish-like, free living, medusa stage, and an Anemone-like, attached polyp stage. In the case of Clinging Jellyfish the polyp is about 5 mm across, and lives on Seagrass blades or Seaweed thali. The medusa stage reaches about 2 cm across, and need to remain in the Seagrass or Algae beds where the medusae live, and have suckers with to attach to themselves, a habit that makes them particularly dangerous to bathers.

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Friday, 25 May 2018

Magnitude 2.5 Earthquake off the coast of Norway.

The British Geological Survey recorded a Magnitude 2.5 Earthquake at a depth of 10 km, about 60 km offshore of the town of Florø in Sogn og Fjordane County, southern Norway, slightly before 7.10 am local time (slightly 6.10 am GMT) on Wednesday 23 May 2018. There are no reports of any damage or injuries associated with this event, though it is likely to have been felt locally.
The approximate location of the 23 May 2018 Norwegian coastal Earthquake. Google Maps.
 Earthquakes are rare in Norway, and the waters between them, and those that do occur tend to be small, which makes the causes hard to determine. The entire of Europe is being pushed eastward by the expansion of the Atlantic Ocean and northward by the impact of Africa from the south, though these are remote from the Kattegat. There are lesser areas of expansion beneath the North Sea and Rhine Valley, both of which will presumably have some effect on southern Scandinavia.

Finally their is glacial rebound; until about 10 000 years ago much of northern Europe was covered by a thick layer of ice. This pushed the rocks of the lithosphere down into the underlying mantle, and now that the ice is gone these rocks are springing back up, albeit very slowly, a process which is not smooth as rocks tend to stick to one-another, and which therefore causes the occasional small Earth tremor.
(Top) Simplified diagram showing principle of glacial rebound. (Bottom) The extent of glaciation in Europe at the last glacial maximum. Wikipedia.
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Thursday, 24 May 2018

Seventeen missing after Cyclone Mekunu sweeps across the Socotra Islands.

Seventeen people are still missing after Cyclone Mekunu swept across the Yemeni Socotra Island group on Wednesday 23-Thursday 24 May 2018. Full details of the missing persons have not been released, but it is understood that four were members of the crew of one of two vessels that sank during the strom, while another three were in a car that was swept away by floodwaters. The storm is expected to make landfall on the southern part of the Arabian Peninsula this weekend, either in eastern Yemen or southern Oman.

Receding floodwaters on Socotra Island (the largest island of the Socotra group) on 24 May 2018. Abdullah Morgan/AP.

Tropical storms are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere.These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

The passage of Cyclone Mekunu till 12.00 GMT on Thursday 24 May 2018 (thick line) with its predicted future path (thin line, circles represent the margin of error on the predictions). Colours indicate the strength of the storm. Tropical Storm Risk.

The low pressure above tropical storms causes water to rise there by ~1 cm for every millibar drop in pressure, leading to a storm surge that can overwhelm low-lying coastal areas, while at the same time the heat leads to high levels of evaporation from the sea - and subsequently high levels of rainfall. This can cause additional flooding on land, as well as landslides, which are are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

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Eleven confirmed fatalities in Nipah Virus outbreak in Kerala State, India.

Eleven people have been confirmed dead and a further fourteen have been confirmed to be infected in an outbreak of Nipah Virus in Kerala State, India, with a further twenty two patients in Kerala and two in neighbouring Karnataka State, The first case was reported in Kozhikode District, Kerala, on Saturday 19 May 2018, since when the disease has spread to Malappuram, Wayanad and Kannur districts in Kerala, and possibly Mangalore in Karnataka State. Not all of the identities of the victims have been released, but four are understood to be members of the same family, while one was a nurse who contracted the Virus while treating the first reported victims at the Perambra Taluk Hospital in Kozhikode.

Nurse Lini Puthussery, 28, a nurse at the Perambra Taluk Hospital in Kozhikode, who died on Monday 21 May 2018 after contracting Nipah Virus from patients she was treating. Deepu Sebin/Twitter.

Nipah Virus is a single-strand RNA Virus in the Family Paramyxoviridae, which also includes the Viruses that cause diseases such as Mumps and Rhinderpest. It is a zoonotic disease (disease with an animal host that sometimes infects Humans), that naturally infects Fruit Bats, but which can infect Humans and domestic animals. Like many zoonotic diseases, Nipah Virus is particularly lethal when infecting Humans, as Humans are not part of their natural life-cycle, with the effect that they are not under evolutionary pressure to keep Human hosts alive in order to perpetuate themselves. Such diseases typically have short duration and a high fatality rate, though epidemics usually burn out quickly.

Nipah Virus infections generally first manifest as a fever, accompanied by headaches, drowsiness and disorientation. This can progress rapidly to encephalitis (inflammation of the brain), which results into patients falling into a coma and dying, often within 48 hours of the initial infection. In some patients the disease also infects the respiratory tract, resulting in breathing problems, and a much higher likelihood of passing on the infection. 

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Asteroid 2018 GJ1 passes the Earth.

Asteroid 2018 GJ1 passed by the Earth at a distance of about 15 693 000 km (40.8 times the average distance between the Earth and the Moon, or 10.5% of the distance between the Earth and the Sun), slightly after 2.50 pm GMT on Thursday 17 May 2018. There was no danger of the asteroid hitting us, though were it to do so it would have presented a significant threat. 2018 GJ1 has an estimated equivalent diameter of 130-410 m (i.e. it is estimated that a spherical object with the same volume would be 130-410 m in diameter), and an object of this size would be predicted to be capable of passing through the Earth's atmosphere relatively intact, impacting the ground directly with an explosion that would be 1850 to 175 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater 2-7 km in diameter and devastation on a global scale, as well as climatic effects that would last decades or even years.

The calculated orbit of 2018 GJ1. Minor Planet Center.

2018 GJ1 was discovered on 8 April 2018 (39 days before its closest approach to the Earth) by the University of Arizona's Catalina Sky Survey, which is located in the Catalina Mountains north of Tucson. The designation 2018 GJ1 implies that it was the 34th asteroid (asteroid J1) discovered in the first half of April 2019 (period 2018 G).

2018 GJ1 has an 885 day orbital period and an eccentric orbit tilted at an angle of 6.80° to the plane of the Solar System, which takes it from 0.81 AU from the Sun (i.e. 81% of he average distance at which the Earth orbits the Sun) to 2.80 AU from the Sun (i.e. 280% of the average distance at which the Earth orbits the Sun, and further from the Sun than the planet Mars). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer). This means that close encounters between the asteroid and Earth are extremely common, with the last having occurred in October 2013 and the next predicted in September 2030. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2018 GJ1 is also classified as a Potentially Hazardous Asteroid.
2018 GJ1 also has frequent close encounters with the planets Venus, which it is thought to have last passed in October 2008, and is next predicted to pass in August 2047, and Mars, which it last came close to in July 1994 and is next predicted to pass in June 2124). Asteroids which make close passes to multiple planets are considered to be in unstable orbits, and are often eventually knocked out of these orbits by these encounters, either being knocked onto a new, more stable orbit, dropped into the Sun, knocked out of the Solar System or occasionally colliding with a planet.
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Determining the diet of Miocene Gomphotheriid Proboscidean using phytoliphs preserved in dental calculus.

The first Proboscideans (Elephants), appeared in the Palaeocene, and like other herbivorous Mammals of this time are presumed to have been browsers (leaf and fruit eaters). Modern Elephants, in contrast, are primarily grazers (grass eaters). Grasses first appeared in the Cretaceous, but extensive grasslands did not become a distinct ecosystem until the Miocene around 23 million years ago. Early Proboscidians had low-crowned teeth, with few lophids (ridges), consistent with a browsing diet, while modern Elephants have high-crowned teeth with numerous lophids, which offers some protection agianst the abbrasive nature of Grasses. The switch to Grasses as a food possibly occured in the Gomphotheres, which appeared in the Middle Miocene and are thought to have been ancestral to True Elephants. The earliest members of the group were trilophadont (had three ridges on their teeth), while later forms, particularly those thought to be ancestral to True Elephants, were tetralophadont (had four ridges), suggestive of a switch towards a more Grass-based diet.

In a paper published in the journal Scientific Reports on 16 May 2018, Yan Wu of the Key Laboratory of Vertebrate Evolution and Human Origins at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and the Center for Excellence in Life and Paleoenvironment, Tao Deng, also of the Key Laboratory of Vertebrate Evolution and Human Origins, and the Center for Excellence in Life and Paleoenvironmentm, and of the Center for Excellence in Tibetan Plateau Earth Sciences, Yaowu Hu and Jiao Ma, also of the Key Laboratory of Vertebrate Evolution and Human Origins, and of the Department of Archaeology and Anthropology at the University of Chinese Academy of Sciences, Xinying Zhou, again of the Key Laboratory of Vertebrate Evolution and Human Origins, and the Center for Excellence in Life and Paleoenvironment, Limi Mao of the Key Laboratory of Economic Stratigraphy and Palaeogeography, at the Nanjing Institute of Geology and Palaeontology, Hanwen Zhang of the School of Earth Sciences at the University of Bristol, and of the Earth Sciences Department at the Natural History Museum, Jie Ye, again of the Key Laboratory of Vertebrate Evolution and Human Origins, and Shi-Qi Wang, once again of the Key Laboratory of Vertebrate Evolution and Human Origins, and the Center for Excellence in Life and Paleoenvironmentm, and of the Center for Excellence in Tibetan Plateau Earth Sciences, examine the diets of two species of Middle Miocene trilophadont Gomphotheriid Proboscideans, by examining phytoliths (silica fragments produced by plants) preserved in dental calculus of six specimens from the Miocene Halamagai Formation in the northern Junggar Basin of Xinjiang Province, China.

The Middle Miocene deposits of the Junggar Basin produce a diverse range of Gomphotheriid specimens, accompanied by floral remains indicative of a largely forested environment. Late Miocene strata from the same area, in contrast, have a much less diverse Gomphotheriid fauna, dominated by a few tetralophadont forms, and a more arid, Grass-dominated environment, suggesting that this area may have played an important role in the switch between browsing and grazing behaviour in early Proboscideans.

Wu et al. examined calculus from four specimens of Gomphotherium connexum and two specimens of Gomphotherium steinheimense. Gomphotherium steinheimense is thought to have been closely related to the early tetralophadont Gomphotheriid Tetralophodon longirostris, while Gomphotherium connexum is a more distant relative.

Geography, geology, and phylogeny in relation to the study material. (A) The location of the study area (black star). The map was generated by GTOPO309 using Globalmapper (v10). (B) Stratigraphic column and polarity with palaeomagnetic age, also denoting the horizon of study material in the strata (in light yellow). (C) The 50% majority consensus tree from 29 maximum parsimonious trees showing the phylogenetic position of the Gomphotherium species and Tetralophodon longirostris, the number at each node representing the support value calculated by majority rules (percentages of supported MPTs in the total MPTs, which are always larger than 50%) and the orange frame indicating the sister-taxon relationship of Gomphotherium steinheimense and Tetralophodon longirostris. (D) Gomphotherium steinheimense, right m3. (E) Gomphotherium connexum, left M3. Wu et al. (2018).

Of the phytoliths obtained from the calculus of Gomphotherium connexum, between 40% and 50% were identified as having originated from Grasses, whereas between 28% and 34% could be identified as having come from broadleaved plants. This would at first seem to imply a diet with a high proportion of Grasses, but Grasses produce a far greater amount of phytoliths than broadleaved plants (hence their more abrasive nature), so this probably indicates a diet with a high proportion of broadleaved plants. In contrast about 85% of the phytolihs from the calculus of Gomphotherium steinheimense could be identified as having come from grasses, indicative of a much more Grass-based diet.

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