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Archive for June 30th, 2009

Seagrass in Crisis

Posted by feww on June 30, 2009

Seagrass is disappearing from the world’s oceans at an accelerating rate

A new study finds that 29 percent of the world’s known seagrass has disappeared since 1879 and the losses were rising exponentially.

Seagrasses—a unique group of flowering plants that have adapted to exist fully submersed in the sea—profoundly influence the physical, chemical, and biological environments in coastal waters, acting as ecological engineers (sensuWright and Jones 2006) and providing numerous important ecological services to the marine environment (Costanza et al. 1997). Seagrasses alter water flow, nutrient cycling, and food web structure (Hemminga and Duarte 2000). They are an important food source for megaherbivores such as green sea turtles, dugongs, and manatees, and provide critical habitat for many animals, including commercially and recreationally important fishery species.—A Global Crisis for Seagrass Ecosystems

Examples of seagrass meadows and associated animals. (a) Seahorse (Hippocampus sp.) in temperate Cymodocea nodosa meadow,Mediterranean Sea. Photograph: Gérard Pergent. (b) School of zebrafish (Girella zebra) over a temperate Posidonia australis meadow, Western Australia. Photograph: Gary A. Kendrick. (c) Manatee (Trichechus manatus) feeding in a tropical Thalassia testudinum meadow, Puerto Rico. Photograph: James Reid. (d) Green sea turtle (Chelonia midas) feeding in a tropical T. testudinum meadow, Yucatán. Photograph: Robert P. van Dam. Source: A Global Crisis for Seagrass Ecosystems

Seagrasses, which are found in coastal waters are vanishing at the rate of about 110 sq km a year since 1980, Reuters reported the study as saying. The report is to be published in the U.S. journal Proceedings of the National Academy of Sciences.

Seagrasses as ecological service providers and biological sentinels Seagrass meadows have important ecological roles in coastal ecosystems and provide high-value ecosystem services compared with other marine and terrestrial habitats (figure below; Costanza et al. 1997). For example, primary production from seagrasses and their associated macro- and microepiphytes rivals or exceeds that of many cultivated terrestrial ecosystems (Duarte and Chiscano 1999). Seagrasses also provide an enormous source of carbon to the detrital pool, some of which is exported to the deep sea, where it provides a critical supply of organic matter in an extremely food-limited environment (Suchanek et al. 1985).Much of the excess organic carbon produced is buried within seagrass sediments, which are hotspots for carbon sequestration in the biosphere (Duarte et al. 2005). The structural components of seagrass leaves, rhizomes, and roots modify currents and waves, trapping and storing both sediments and nutrients, and effectively filter nutrient inputs to the coastal ocean (Hemminga and Duarte 2000).—A Global Crisis for Seagrass Ecosystems

Only about 177,000 sq km of seagrasses are left globally.

The study by Australian and American scientists compares the losses to that of coral reefs, tropical rainforests and mangroves. It says seagrass meadows are “among the most threatened ecosystems on earth,”  blaming the loss on population growth, development, climate change and ecological degradation of the oceans.

“Seagrasses are sentinels of change” and the loss of seagrass was an indicator of a deteriorating global marine ecosystem. “Mounting seagrass loss reveals a major global environmental crisis in coastal ecosystems,” the report said.

seagrass ecosystem services - major loss mechs

Moreover, seagrasses can be considered as biological sentinels, or “coastal canaries.” Changes in seagrass distribution, such as a reduction in the maximum depth limit (Abal and Dennison 1996) or widespread seagrass loss (Cambridge and McComb 1984), signal important losses of ecosystem services that seagrasses provide. Seagrasses are sessile, essentially integrating the relevant water quality attributes, such as chlorophyll and turbidity, that affect the light reaching their leaves. Several features of seagrasses and seagrass meadows result in their particular importance in this regard.The widespread distribution of seagrasses throughout tropical and temperate regions (figure 2) allows better assessment of larger-scale trends than do other comparable coastal habitats, such as mangrove, corals, or salt marsh plants, which are limited to only one of these broad geographic regions. Seagrasses also live in shallow, protected coastal waters, directly in the path of watershed nutrient and sediment inputs, and are therefore highly susceptible to these inputs (figure 4), unlike mangrove forests (which are largely unaffected by water quality) or coral reefs (which occur farther away from the imputs).—A Global Crisis for Seagrass Ecosystems

Some 70 percent of all marine life in the ocean directly depends on seagrass, U.S.-based Seagrass Recovery said.

“Seagrass losses decrease primary production, carbon sequestration and nutrient cycling in the coastal zone. If the current rate of seagrass loss is sustained or continues to accelerate, the ecological losses will also increase, causing even greater ill-afforded economic losses,” said the study.

In addition to the well-documented causes of seagrass declines, other threats to these species are emerging. Over the last 20 years, introductions of nonnative marine species have arisen as a major environmental challenge for the world’s oceans (Carlton 1989). Such introductions are accelerating worldwide (Ruiz et al. 2000), a trend that will continue as the pathways for introductions widen and proliferate and as intervention lags (figure 6b; Naylor et al. 2001, Levine and D’Antonio 2003, Padilla and Williams 2004). At least 28 nonnative species have become established in seagrass beds worldwide, of which 64% have documented or inferred negative effects (figure 6b). The concern about this emerging threat to seagrass beds is that, whereas it is possible to reverse eutrophication or cease dredge-and-fill activities, it is virtually impossible to remove a nonnative species after establishment and spread (Lodge et al. 2006). Lastly, the rapid expansion of fish farming and other aquaculture practices (e.g., shellfish culture) can have serious consequences on local populations of seagrasses through physical disturbance or increased deposition of organic matter and nutrients (Marbà et al. 2006).—A Global Crisis for Seagrass Ecosystems

The preservation of seagrasses and their associated ecosystem services—in particular, biodiversity, primary and secondary production, nursery habitat, and nutrient and sediment sequestration—should be a global priority.We believe that the crisis facing seagrass ecosystems can be averted with a global conservation effort, and this effort will benefit not just seagrasses and their associated organisms but also the entirety of coastal ecosystems. —A Global Crisis for Seagrass Ecosystems

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Shiveluch spewes large plumes of ash

Posted by feww on June 30, 2009

Shiveluch volcano on the Kamchatka Peninsula ejects ash to a height of 7km

Shiveluch volcano on the Kamchatka Peninsula, Russia’s northernmost active volcano,  spewed out ash to a height of some 7,000 meters (23,000 feet), the local geophysics service reported on Monday.

The service had registered about 60 tremors within the area in the previous 24 hours.

“Some of them were followed by powerful ash bursts and avalanches,” a spokesman for the service said.

Shiveluch volcano erupted in December 2006. Local scientists expect the volcano to erupt explosively soon.

“Volcanic activity over the past two-three years has significantly altered the contour of the volcano, with the crater increasing in size by 50% and the slopes becoming far steeper.” RiaNovosti reported.

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Previous Comments by FEWW

FEWW Volcanic Activity Forecast

Posted in Explosive Eruption, Kamchatka peninsula, Kamchatka volcanoes, Koryakski volcano, Russian volcano | Tagged: , , , , | Leave a Comment »

Airbus Crashes in Comoros

Posted by feww on June 30, 2009

Yemenia Airbus A310 with 153 People Crashes in Comoros

Yemenia-Airbus-A310A Yemen Airways (Yemenia) Airbus A310 with 153 people onboard crashed in the Indian Ocean near the archipelago of Comoros earlier today, according to an airline official.

Most of the 142 passengers  (total of 153 people onboard) were Comoran or French. There are no report of  survivors.

Yemenia Airbus A310. Source: Image may be subject to copyright.

The downed Yemenia Airbus A310 passenger jet was flying from Sanaa, Yemen,  to Moroni, in the Comoros, carrying also a 11-strong crew, Reuters reported an official as saying.

The Comoros (Population of 800,000), which consists of four small volcanic islands (Anjouan, Grande Comore, Moheli and Mayotte) in the Mozambique channel, about 300 kilometers northwest of Madagascar, is not believed to have any sea rescue capabilities.

Comoros map

Map of the Comoros Islands. Original map: UN.

“We still do not have information about the reason behind the crash or survivors,” the deputy general manager for Yemenia operations, said.

“The weather conditions were rough; strong wind and high seas. The wind speed recorded on land at the airport was 61 kilometers an hour. There could be other factors.”

“Two French military aircraft have left from the islands of Mayotte and Reunion to search the identified zone, and a French vessel has left Mayotte,”the director general of Moroni International Airport was reported as saying.

“The plane has crashed and we still don’t know exactly where. We think it’s in the area of Mitsamiouli,” Comoros Vice-President Idi Nadhoim told Reuters.

“We think the crash is somewhere along its landing approach,” Mr Kassim a representative from regional air security body ASECNA said. “The weather is really not very favorable. The sea is very rough.”

Reuters sketch showing the flight path of downed Yemenia Airbus. Image may be subject to copyright.

Who owns Yemenia?

Yemenia is 51 percent owned by the Yemeni government and 49 percent by the Saudi Arabian government. Yemenia’s fleet includes four Airbus A310-300s, two Airbus A330-200s and four Boeing 737-800s, according to the airline site.

Airbus Crash Stats

If you really have to fly because your life depends on it [sic,] and if you are flying an Airbus, then fly on odd days of the month because the Airbus is statistically twice more likely to crash on even days!

The Next Airbus Crash?

The probability that the next major air disaster would involve an Air New Zealand Airbus has now increased to 0.78.

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Posted in air new zealand, airline disasters, airline safety, comoros crash, french connection | Tagged: , , , , | 4 Comments »