Amir Mohsen
متخصص بخش هواشناسی
Dramatic shifts from floods to drought and back to floods may be a sign of what's to come due in part to global warming
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Amir Mohsen
متخصص بخش هواشناسی
Warmer Seas May Impact Antarctic Clams’ Reproduction
By Kieran Cooke, Climate News Network
LONDON — Antarctic clams (Laternula elliptica) play a vital role in the ocean ecosystem, drawing down carbon into sea-bed sediments and circulating ocean nutrients.
Now a new study has found that the reproductive capacity of this long-lived and abundant species — existing in the cold, oxygen-rich waters of the Antarctic — could be seriously affected by rising ocean temperatures.
The study, by scientists at the British Antarctic Survey (BAS) and from the University of Kiel and the Alfred Wegener Institute in Germany and published in the journal Global Change Biology, found that young clams examined — averaging 3 years old — tended to try to move and bury themselves deeper when they sensed warmer ocean temperatures or reduced oxygen levels.
An Antarctic clam (Laternula elliptica).
Credit: National Museum of Natural History
But more mature clams — of around 18 years old — stayed put. This, say scientists, is important as it is the older clams, not the younger ones, which reproduce. If they don’t adapt, their existence could be threatened.
“The polar regions are the Earth’s early warning system and Antarctica is a great natural laboratory to study future global change”, says Dr. Melody Clark of the BAS, the lead author of the study.
“These small and rather uncharismatic animals can tell us a lot about age and survival in a changing world — they are one of the ‘engines of the ocean’.
“We know that they are extremely sensitive to their environment. Our study suggests that the numbers of clams that will survive a changing climate will reduce.”
Antarctic clams, which can live up to 36 years, have evolved in stable temperatures over the centuries. But scientists say sea surface temperatures around the Antarctic Peninsula have risen by 1°C (1.8°F) over the last 50 years.
[h=4]Age Reduces Mobility As with humans, the muscle mass of clams decreases with age, making them more sedentary. The study, which follows on from earlier research, confirmed that it is these older, reproductively active clams which will suffer most from rising water temperatures.
The study involved divers collecting both young and older clams from the the seabed off King George Island and adjacent to a BAS research station on the Antarctic Peninsula.
The clams were then placed in aquarium tanks simulating different environmental conditions, with reactions to variations in oxygen and nitrogen levels monitored. Older clams showed little sign of movement in warmer waters with less oxygen while younger clams tended to be more active.
“We are trying to correlate long term predictions for clam populations”, Dr. Clark told the Climate News Network. “What is interesting with clams is that their shells show their age more or less exactly and we are therefore able to monitor their behavior at different stages of the life cycle, in differing conditions.”
Doris Abele of the Alfred Wegener Institute says the study shows the physiological flexibility of young clams diminishes as they get older.
“However, the species has evolved in such a way that the fittest animals, that can tolerate life in an extreme environment, survive to reproduce into old age. Climatic change, affecting primarily the older clams, may interfere with this evolutionary strategy, with unpredictable consequences for ecosystems all around Antarctica.”
Kieran Cooke is joint editor of Climate News Network. Climate News Network is a journalism news service led by four veteran British environmental reporters and broadcasters. It delivers news and commentary about climate change for free to media outlets worldwide.
- Published: April 28th, 2013
By Kieran Cooke, Climate News Network
LONDON — Antarctic clams (Laternula elliptica) play a vital role in the ocean ecosystem, drawing down carbon into sea-bed sediments and circulating ocean nutrients.
Now a new study has found that the reproductive capacity of this long-lived and abundant species — existing in the cold, oxygen-rich waters of the Antarctic — could be seriously affected by rising ocean temperatures.
The study, by scientists at the British Antarctic Survey (BAS) and from the University of Kiel and the Alfred Wegener Institute in Germany and published in the journal Global Change Biology, found that young clams examined — averaging 3 years old — tended to try to move and bury themselves deeper when they sensed warmer ocean temperatures or reduced oxygen levels.
Credit: National Museum of Natural History
But more mature clams — of around 18 years old — stayed put. This, say scientists, is important as it is the older clams, not the younger ones, which reproduce. If they don’t adapt, their existence could be threatened.
“The polar regions are the Earth’s early warning system and Antarctica is a great natural laboratory to study future global change”, says Dr. Melody Clark of the BAS, the lead author of the study.
“These small and rather uncharismatic animals can tell us a lot about age and survival in a changing world — they are one of the ‘engines of the ocean’.
“We know that they are extremely sensitive to their environment. Our study suggests that the numbers of clams that will survive a changing climate will reduce.”
Antarctic clams, which can live up to 36 years, have evolved in stable temperatures over the centuries. But scientists say sea surface temperatures around the Antarctic Peninsula have risen by 1°C (1.8°F) over the last 50 years.
[h=4]Age Reduces Mobility As with humans, the muscle mass of clams decreases with age, making them more sedentary. The study, which follows on from earlier research, confirmed that it is these older, reproductively active clams which will suffer most from rising water temperatures.
The study involved divers collecting both young and older clams from the the seabed off King George Island and adjacent to a BAS research station on the Antarctic Peninsula.
The clams were then placed in aquarium tanks simulating different environmental conditions, with reactions to variations in oxygen and nitrogen levels monitored. Older clams showed little sign of movement in warmer waters with less oxygen while younger clams tended to be more active.
“We are trying to correlate long term predictions for clam populations”, Dr. Clark told the Climate News Network. “What is interesting with clams is that their shells show their age more or less exactly and we are therefore able to monitor their behavior at different stages of the life cycle, in differing conditions.”
Doris Abele of the Alfred Wegener Institute says the study shows the physiological flexibility of young clams diminishes as they get older.
“However, the species has evolved in such a way that the fittest animals, that can tolerate life in an extreme environment, survive to reproduce into old age. Climatic change, affecting primarily the older clams, may interfere with this evolutionary strategy, with unpredictable consequences for ecosystems all around Antarctica.”
Kieran Cooke is joint editor of Climate News Network. Climate News Network is a journalism news service led by four veteran British environmental reporters and broadcasters. It delivers news and commentary about climate change for free to media outlets worldwide.
اون سال آژیر کشیده بودن مردم فکر کردن موشک باران هست همه رفته بودن زیر زمین ها و پناهگاه ها .
یکی از اشنایان من هم اون سال اونجا بود شانس اورده بود فاصله با پناه گاه زیاد بود . نرفته بود پناهگاه .
دقیقا کار مونسون هستش
جنوب کشور یمن هم همچین جنگل هایی هستش...
اینم عمان هستش: همین مناطق سرسبز عمان بعضی مواقع دما تا بالای 45 درجه هم میره. خیلی گرمه...
مشکل اینجاست که همیشه خشکی و گرما برای ماست و بارش برای دیگران هست . امسال خاورمیانه کلا پر بارش بود به غیر از ایران .
متاسفانه به نظر می رسه همینطوره
در نظر خیلی از چشم سبزای مو بور ایران خیلی گرمتر و خشکتر از وضعیت واقعیه
مثلا خیلی از اونا بارش برف رو برای شهرهای ایران متصور نیستن و اقلیم ایران رو چیزی شبیه عراق یا مصر تصور میکنن
navid-mashhad
کاربر ويژه
یمن هم جنگل هایی داره به همین جهت و به دلیل بارش بیشتر نسبت به حجاز دارای تمدن بسیار دیرینه ای هست
در گذشته به یمن عربستان سعید ( خوشبخت ) گفته می شده!!! البته الان برعکسه!!!
منم دوست داشتم اونجا بودی!دوست داشتم الان بالای این ماشین می بودم!
Amir Mohsen
متخصص بخش هواشناسی
درود آبتین عزیز
این تعبیر بالا رو از این جهت نوشتم چون داره در نواحی جنوبی ایران برای دومین بار از ابتدای سال جدید رخ میده!!
این تعبیر بالا رو از این جهت نوشتم چون داره در نواحی جنوبی ایران برای دومین بار از ابتدای سال جدید رخ میده!!
92 ناهنجار
Banned
سلام دوستان.........
با این تفاسیر بنده از این که نام کاربری خود را 92 ناهنجار انتخاب کردم اصلا پشیمان نیستم و کم کم داره تحقق پیدا میکنه این شعار بنده....:خنده1:
با این تفاسیر بنده از این که نام کاربری خود را 92 ناهنجار انتخاب کردم اصلا پشیمان نیستم و کم کم داره تحقق پیدا میکنه این شعار بنده....:خنده1:
آخرین ویرایش:
Amir Mohsen
متخصص بخش هواشناسی
[h=2]Wild Weather Wreaks Havoc in Middle East
[h=6]By Eric Leister, Meteorologist [h=5]April 29, 2013; 8:25 AM
Share |
Weather headlines across the world are detailed in the above AccuWeather.com video.
A recent stretch of unsettled weather across the Middle East is expected to continue through at least the middle of the week.
The wild weather ranged from strong thunderstorms in Afghanistan to flooding in southern parts of the Arabian Peninsula to hail storms across northern Saudi Arabia.
The unsettled weather began almost a week ago when a thunderstorm brought heavy rain, wind and damaging hail to southern Afghanistan. The storm hit a military base damaging about 50 helicopters, according to a service member at Kandahar Airfield.
The bad weather was not limited to southern Afghanistan, as parts of the north experienced flash flooding that resulted in at least 20 deaths and destroyed thousands of homes.
Flash flooding was a major issue from Yemen into southern Saudi Arabia and Oman since last week, as several rounds of heavy rainfall targeted the region.
Flash flooding across Oman forced the Royal Oman Police (ROP) into action as helicopter rescues were increased in frequency over the weekend. More than 50 people were rescued by the aircraft.
Reports from the ROP indicate that at least 12 people have died in the rounds of flash flooding in the past week.
In Yemen, heavy rainfall led to flash flooding in the capital city of Sana'a which in turn led to travel problems.
Another round of stormy weather erupted across northern Saudi Arabia over the weekend as storms blanketed the ground with hailstones around the city of Ha'il. Rainfall amounts totaled more than an inch on Saturday, surpassing the monthly average for all of April in a single day.
[h=6]By Eric Leister, Meteorologist [h=5]April 29, 2013; 8:25 AM
Share |
Weather headlines across the world are detailed in the above AccuWeather.com video.
A recent stretch of unsettled weather across the Middle East is expected to continue through at least the middle of the week.
The wild weather ranged from strong thunderstorms in Afghanistan to flooding in southern parts of the Arabian Peninsula to hail storms across northern Saudi Arabia.
The unsettled weather began almost a week ago when a thunderstorm brought heavy rain, wind and damaging hail to southern Afghanistan. The storm hit a military base damaging about 50 helicopters, according to a service member at Kandahar Airfield.
The bad weather was not limited to southern Afghanistan, as parts of the north experienced flash flooding that resulted in at least 20 deaths and destroyed thousands of homes.
Flash flooding was a major issue from Yemen into southern Saudi Arabia and Oman since last week, as several rounds of heavy rainfall targeted the region.
Flash flooding across Oman forced the Royal Oman Police (ROP) into action as helicopter rescues were increased in frequency over the weekend. More than 50 people were rescued by the aircraft.
Reports from the ROP indicate that at least 12 people have died in the rounds of flash flooding in the past week.
In Yemen, heavy rainfall led to flash flooding in the capital city of Sana'a which in turn led to travel problems.
Another round of stormy weather erupted across northern Saudi Arabia over the weekend as storms blanketed the ground with hailstones around the city of Ha'il. Rainfall amounts totaled more than an inch on Saturday, surpassing the monthly average for all of April in a single day.
92 ناهنجار
Banned
و علیکم السلام برادر سیبری....
آقا چرا به عربی صحبت می کنید.....
بله مشاهده می کنم که چه اتفاقی داره در عربستان میفته...
اجازه دهید تا برم چند تا عکس و تصویر دیگه براتون بزارم....
نعم سیدی عندی تصاویر الامطار D:
Amir Mohsen
متخصص بخش هواشناسی
ظاهرا باید واسه علاقه دوستان به زبان عربی در یک انجمن persian ( پارسی) چاره ای جدی بیاندیشم!!!!!!!!
انا مشتاق بتصاویرکم کما اشتیاق طفل لحلب امها!
- وضعیت