Arabian Sea & Climate Change

Fish Kills

2008-10-06T16:00:00.002-04:00

What does "Fish kills" mean? What are the mechanisms behind Fish kills and what are the impacts? How does this relate to the climate change research in the Arabian sea?

"Fish kills" is a term used to describe an event in which a large amount of marine life dies off over a period of time due to natural or unnatural causes. This event is usually restricted to coastal and estuarine ecosystems and can be caused by any combination changes in biological, chemical or physical processes(1).

[Image source: Google earth, fish kill events gathered from various articles from over the past decade or so]

Phytoplankton growth is a pivotal part of any marine ecosystem because algae form the base of the food chain. Algal blooms depend mainly on sunlight and the availability of nutrients like phosphorus (p) and nitrogen (n). Naturally, phytoplankton blooms occur as a result of upwelling events. Upwelling is a process by which cold nutrient rich water is brought to the surface from the deep as a result of wind moving across the ocean. With more nutrients available in the photic zone (the area in which there is sufficient sunlight present that is needed for photosynthesis) phytoplankton growth accelerates. One cause of fish kill events is when high nutrient levels cause massive phytoplankton blooms which result in the depletion of the dissolved oxygen in the water (eutrophication). When phytoplankton use up all the excess nutrients, they die and fall from the photic zone. As the dead phytoplankton sinks, it is broken down by bacteria which consume oxygen. Lack of oxygen strains marine biota by slowing metabolism, reproduction and movement speed; all of these affects make fish vulnerable to predators and fisherman. Cheryl Lyn Dybas (2005) states that under fully oxygenated conditions, all life functions normally. Under low oxygen or hypoxic conditions fish begin to experience difficulty breathing when the oxygen concentration is about 5ppm. When the oxygen concentration reaches about 3ppm, sharks leave the area and when the oxygen concentration reaches 2ppm fish leave the area. Below 1.5ppm all life that do not or cannot leave the area, die (2)(3). Areas devoid of marine life are referred to as dead zones. The image on the left illustrates how dead zones are formed. [Image source: How dead zones are formed (EPA 2007)]

In addition to upwelling, excess nutrients inputs come from:

Agricultural runoff,
Atmospheric deposition
Erosion
Runoff from developed land (i.e. lawn fertilizer, sewage etc)

Bacterial from sewage runoff and contaminated fish feed at aquaculture centers have been found to cause fish kill events.

Scientists have found that because the Arabian Sea has naturally high productivity (conversion of solar energy, carbon dioxide and water into forms available for use in the food web), that it has one of the thickest zones of oxygen depleted water (below 100m depth). The Arabian Sea area is heavily influenced by its monsoon seasons which cause upwelling events which make up a large portion of the nutrient influx for the area. Other nutrient sources are dust storms from the Arabian peninsula, and environmental pollution (agricultural, ballast release, chemical residue from the war zones etc...)

(In my research on fish kills I have come up with a question. Knowing that the Arabian Sea is naturally lower in oxygen concentration, what is the natural average concentration of dissolved oxygen in the Arabian sea?)

For example, environmental pollution has had a huge impact on the Shatt-Al-Arab river estuary which empties into the Kuwait Bay. For more information visit: http://www.unep.org/geo/geo3/english/480.htm

Climate change is an interconnected event based on long term change of regional weather which is thought to be caused by an increase in atmospheric carbon. It is thought that climate change is causing global warming. In the Arabian Sea, it has been recently suggested that climate change is also causing intensified monsoon winds and in turn, intensified upwellings. With intensified upwellings, there have been larger algal blooms as a result (4). This is a possible hypothesis for why there has been such of an increase in fish kill events over the past few decades.

Knowing that there is an increase in upwelling and productivity in the Arabian Sea, there is also an increase in upwelling of anoxic water which has been known to cause fish kills. In late August of 2000, a fish kill event occurred off the northern coast of Oman in the Persian gulf. Although the media attributed the deaths to a release of ballast water from a US tanker, Dr. John M. Morrison, a professor of Oceanography at North Carolina State University, found that the event was due to upwelling. Satellite imaging captured the upwelling event which can be seen to the right. In the top image, the sea surface temperatures are normal as evidence by the pink/orange colors, however the bottom image was taken 10 days later there is significantly more blue/purple coloring which means that cold water was upwelled.

Dead zone-fish kill events are usually preceded by large catches of fish and then discoloration of surface water because of the algal bloom. This notion originally led Dr. Morrison to believe the upwelling was nutrient rich. However after testing, it was determined that pockets of oxygen depleted water was upwelled due to an unusual and strong easterly wind. Fisherman experienced a bountiful catch because all fish in the area were compacted in the small pockets of oxygen rich waters and therefore easier to catch. For more information about fish kills off the coast of Oman, visit these websites: http://earthobservatory.nasa.gov/Study/oman/, http://news.bbc.co.uk/2/hi/world/monitoring/media_reports/908134.stm.

The mechanics of a pathogen fish kill are much more simple. A pathogen is introduced into the water and fish become effected. However due to climate change we are dealing with an intensified scale of infection. With even slight increases in temperature and pH of the water it becomes more difficult for marine life to function normally. It effects body temperature, metabolism and reproduction. This makes marine biota more susceptible to pathogens of any kind.

From July to December 2007, in Maldives there were many fish kill events. Researchers suggest that these events were caused by a number of reasons including exposure of the O. nigers to harmful algal blooms and the prescence of Streptococcus sp. which is a species of bactera known to be associated with fish kills. This bacteria was found in the spleen of the dead fish. There was also a similar report in the 1980s from off the coast of Sri lanka in a case where O. nigers were killed (1). However according the the author of "A compilation of reported fish kills in Maldives," the study was not conclusive and that more testing and funding is needed.

Biodiversity is defined as the natural variation of species in a given ecosystem. Increased biodiversity results in a healthier population. Dead zones can be restored with the addition of oxygenated water (either from wind driven mixing or upwelling), however the stocks will have trouble recovering due to missing links in the ecosystem like the bottom dwelling life. Disease based fish kill events also affect the biodiversity of the area in that species of fish experiencing mass die-offs. However it must also mean that fisherman are out catching different stock that they might not normally, yes?

Socially, cultures with fishery based economies must be largely affected by fish kill events. The occurance of a fish kill event must lead to a lack of food for fisherman's family, a lack of product to export for income and on top of that increased prices due to demand. What I want to know is how these events affect specific locations like a large coastal country like Oman and Kuwait whose economies are not based solely on fisheries verses an island nation like the Republic of Maldives where fishing is key?

1. Naeem, S. and S.A. Sattar, A compilation of reported fish kills in Maldives. 2007, Marine Research Centre Ministry of Fisheries, Agricultrue and Marine Resources. In the Oman and the Arabian sea
2. Dybas, C. L. (2005). "Dead Zones Spreading in World Oceans." BioScience 55(7): 552-557.

3. Armbrecht, C. (2007). "Dead zones"
4. Goes, J., et al. Eurasian Warming, Snow melt and phytoplankton blooms in the Arabian Sea. 2007 [cited 2008 25 March 2008]; Available from: www.bigelow.org/climatechange/.

Melting Glaciers- Himalayas

2008-07-08T15:30:00.001-04:00

What do glaciers melting in the Himalayas have to do with the Indian Ocean? How could something happening on land be connected to the sea? There is in fact a relationship:

Warming temperatures over Eurasia have caused the snow caps over the Himalayas to shrink. This decrease in snow cover has led to a change in the land-ocean thermal gradient which favors stronger summer monsoon winds in the Indian Ocean. The strengthening of these winds has enhanced upwelling (the process where nutrient rich water from the deep is brought to the surface) in ocean. Consequently, the amount of phytoplankton off of the coasts of Somalia and Oman has greatly increased. (see Prasad & Bigelow related websites and Goes, et al (2005) Science 308, 545-7. DOI 10.1126/science.1106610 for more information)

Current research finds the seasonal spring melting of snow cover over much of Eurasia is faster and more intense than before (personal communication). The Himalayan glaciers are the second largest body of ice in the world, covering 17% (3 million hectares) of the mountain area. Unfortunately, the Himalayan glaciers are retreating faster than any other glaciers (IPCC (2007) Climate Change 2007: Impacts, Adaptation and Vulnerability). The image below shows the approximate recession of the Gangotri glacier- one of the largest glaciers in the Himalayans. From 1780 to 2001 this glacier retreated almost 2 km.

(image from: NASA Earth Observatory- Jesse Allen)

Scientists monitor glaciers and ice caps because they "are key indicators and unique demonstration objects of global climate change" (WGMS. 2007. Glacier Mass Balance Bulletin No 9.). One way of monitoring is to measure the net mass balance of a glacier. The mass balance is the difference between the accumulation and ablation (melting and evaporation) of a glacier. The World Glacier Monitoring Service has been collecting information on two Himalayan glaciers. According to the mass balance data (below) the Chhota Shigri and Hamtah glaciers have an overall mass balance loss for the last three years measured.

Chhota Shigri -1227 mm; +144 mm; -1413 mm

Hamtah -1857 mm; -1856mm; -1391 mm

(Data from 2003/04; 2004/05; and 2005/06* respectively.) *preliminary data

A Call for Data and Cooperation

Compared to other glaciers around the world, there is a lack of information on the impact of global warming on the Himalayan glaciers. Described as a "a blind spot, a big scientific question mark" scientists are working to correct this gap. Over 70 international climate scientists met in April 2008 to begin the task of mapping glacial retreat in the Himalayas. This task will not be easy, either scientifically or politically (see article for more information). This collaboration, along with the current research on the affect of the melting Himalayan glaciers on the productivity of the Arabian Sea, will help us further understand the impact of climate change.

Social Impacts

Millions of people in Pakistan, Nepal, Bhutan, India & Bangladesh rely on the glacial melt waters from the Himalayan glaciers. A decline in glacier mass balance can mean less water available for rivers. It is a worry that the receding glacier trend could lead to the Ganga, Indus, Brahmaputra and other rivers in northern India becoming seasonal rivers (IPCC 2007). If these major rivers are dry during the summer months irrigation, water and food supplies will be affected.

(Himilayan Glaciers map from Zemp. 2007. Glaciers and Ice Caps)

Glacial lakes are formed by melt water, and many in the Himilayas are full. Scientists and politicians are concerned that these 'brimming' lakes may overflow (outburst) and cause devastating floods (see Zemp, 2007. Glaciers and Ice Caps in Global Outlook for Ice and Snow for more information).

Teleconference Minutes (20080627 11:30EST)

2008-07-01T11:00:00.009-04:00

Present: Joaquim Goes, John Fasullo, John Kindle, Fei Chai, Sergio deRada

AGENDA:
1) Participation in the Conference to be held in Oman in March 2009
2) Resolving problems with NOGAPS and NCEP-NCAR wind products and moving forward in the context of our project goals
3) Manuscripts
4) Sept. 2008 Meeting at NRL, Stennis Space Centre

SUMMARY OF DISCUSSIONS:
1) Participation in the Conference held in Oman in March 2009 is encouraged (http://www.squ.edu.om/tropicalcyclones). We will have partial support from the ministries for accommodations, so individual travel expenses will only be for the airfare which was quoted (as of June 27) at around $1200.00. Participants will have to submit an extended abstract (before August 30, 2007) and paper and if there are at least 4, there will be a special session for this topic.

2) Motivated by the initial NOGAPS trend plots made by John Fasullo, discussions about forcing (wind) products were conducted in an effort to focus the research towards achieving the goals set forth in the hypothesis. Given that NOGAPS (available only from 2000) is not reproducing the desired trends in Goes, et al. Paper, which was the foundation of the proposal, the group discussed the usage of other products to force the ocean model. NOGAPS could be used for modeling ocean response to storms and meso-scale features of interest in the area that could lead to procure new funding, but does not seem to suit the purposes of this research.

NCEP: Considerations to run the ocean model from 1995 (2 years spin up) with NCEP atmospheric forcing were discussed. The simulation will only be relaxed to WOA surface salinity and MCSST surface temperature in an effort to attribute the model response mainly to the atmospheric forcing. This will allow us to have a base simulation using the data from which the paper is based.
ERA 40: Reanalysis product from ECMWF is not a viable choice because it ends in 2001 and forcing data are needed through at least 2005.
SeaWINDS: Is a QuickScat-derived product suggested by Fei Chai which covers the period (1997 to 2004) of interest and into the present. John Fasullo will do trend analysis of this product to assess their feasibility. The question that remains is "What to use for heat fluxes if these winds are suitable?"

Once John Fasullo performs initial analysis of trends in the SeaWINDS product, a collective decision will be made for new ocean model simulations, most likely being 2 long-term simulations: One using NCEP forcing, and the second using SeaWINDS (heat fluxes to be determined), both starting around 1995 for a 2 year spin-up and running through 2004 (Paper analysis is from 1997-2004), and possibly extending into the present.

3) Suggested manuscripts will be exchanged by email with members of the project for potential publication and/or presentation in OMAN.

4) There will be a "mini" project meeting at Stennis Space Center, MS on September 9 and 10, 2008. This allows travel days on the 8th and the 11th or 12th and possibly a weekend in New Orleans, but please allow at least both full days (9th and 10th) as there will be plenty to discuss. I would suggest informal presentations on Tuesday as we did in Maine to start the meeting. Some Logistics:

Airports close to Stennis are: New Orleans (MSY) and Gulfport (GPT). They are both about 1hr away, but MSY is a much bigger and better served airport.
Accomodations can be done at the B&B 2 blocks from my house. I get a healthy discount and it's a nice, quite, and convenient place to stay, including being able to ride to Stennis together. I can arrange the reservations once everyone confirms. Here is the place: http://www.woodridgebb.com/.
I plant to host dinner at my house (short walk from the B&B) one of those nights. New Orleans is also a nice place to visit and the food is great. (~45 minute drive from Slidell).
For anyone that is not a U.S. Citizen, we need to do some paperwork to approve their visit to SSC way in advance, so please email me directly as soon as possible so we can start the paperwork.

Please post comments clarifying any of the above, but I think it would be more efficient to "discuss" issues via emails among the group.

Consequences of Cyclone Gonu

2008-06-10T11:19:00.013-04:00

It has been just over a year since the Super Cyclone Storm Gonu (category 5 SSHS). It is the strongest storm to ever hit the Arabian Sea, with top winds of 240 km/h (150 mph). The US experienced the wrath of a category 5 storm in 2005 with Hurricane Katrina, and is still recovering from its damage. This leads me to ask, what have been the impacts of Gonu? What consequences have you seen from this category 5 storm?

[Cyclone Gonu June 4, 2007 09:00 UTC. Image Source: NASA / Aqua Satellite / MODIS]

Social Impacts

Wikipedia reports that Gonu's devastation reached across Oman, the United Arab Emirates, and Iran. Sadly, 72 people died and there was an estimated $4.2 billion (USD) worth of damage- RO1.25-1.5 billion ($4 billion USD) in Oman alone.

[Picture by David Dennison. Image source: BBC]

I have read about the torrential winds, heavy rains and high waves. Images of flooded streets, destroyed cars, the damaged Al Qurm National Park, etc. are haunting. What impacts have you seen? Do you still see a year later?

Climate Impacts

One interesting article I read, stated that Gonu delayed the arrival of South-West Monsoon last year. In the Arabian Sea the SW Monsoon is very influential on phytoplankton through its impact:

on upwelling nutrient-rich deep waters to the coast
on transferring this water to other regions, and
on keeping phytoplankton in the euphotic zone where photosynthesis can occur

[Goes, et. al (2005) Science 308, 545-7. DOI 10.1126/science.1106610]. So, in the ocean what were the consequences from this delay of the monsoon? How was the production of phytoplankton, zooplankton, fish, etc affected? Did delays cascade up the food web?

Welcome!

2008-05-19T14:16:00.008-04:00

Hi!

My name is Carrie and I am studying climate change in the Arabian Sea. I started this blog hoping to begin a global conversation. So much is happening in the area right now, and I think it would be great to share questions, stories, photos, thoughts, research, news, etc.

I work with a group of scientists who are studying climate change in the Arabian Sea, so I will be able to post some of what they are finding out. But, I do not live in the Arabian Sea, so I do not directly see what is going on. I would love you to comment, ask questions, send me links, anything.

Welcome to the Arabian Sea & Climate Change blog! I cannot wait to meet you and read your comments. Let me know who you are, where you are from and what you want to talk about.

-Carrie