Friday, November 19, 2010
It has been a long time since our last entry, and the ocean has been quite busy.
Coastal ocean transitions can often be indicated by temperature trends. To the right is a graph of surface water temperatures at the Newport Pier for this year. The red line is the 2010 data and the black line represent the 5-year average from 2006 to present. The temperature plot is extremely interesting. This past winterthe temperatures were above average through April likely because of the El Nino influence. The winter months saw unseasonably warm waters (about 16C/61F) and a below average occurrence offewer phytoplankton blooms than we expected. The blooms are typically associated with a decrease in temperature that is regularly related to upwelling bringing of cool, and nutrient -rich waters to the surface.
The system transitioned from the warm El Nino conditions throughout last winter and spring to a summer dominated by cold temperatures about 3-5C below average. In fact, most of July, August, and September (about 14.5C/58F) temperatures were cooler than the winter temperature seen from January until April. This year is starkly different than the 5 year average trend which shows that July through September are the warmest months. The unusually cool temperature observations correlated with atypical summer phytoplankton biology. Phytoplankton blooms that are generally expected to occur in spring instead occurred during the cool periods of summer. These blooms included blooms of Pseudo-nitzschia, a harmful toxin-producing algal bloom species.
Currently in mid-November the number of Pseudo-nitzschia is again on the rise. It usually is a rare species making up less that 1% of the phytoplankton in the local community, but now Pseudo-nitzschia is abundant enough to be considered a common species making up 10-24% of the community. The recent increase in Pseudo-nitzschia corresponds to a decrease in temperature in early November. The decreased temperature suggests that nutrient rich waters, which could support Pseudo-nitzschia growth that we are seeing along our coast, are closer to the surface.
The temperature plot was compiled by Stacy Kim, a USC undergrad who volunteers in our lab.
Tuesday, April 6, 2010
Previous blog entries have hinted at our interest in understanding toxic or harmful algal blooms. The global rate of harmful algal blooms (HABs) has been increasing for decades with longer bloom duration, increased toxicity, and greater geographic coverage. HABs are simply defined as significant increases in phytoplankton biomass with harmful consequences. HABs cause harm by producing toxins or because the accumulated biomass negatively impacts food-web dynamics and ecosystem structure, such as decreasing the oxygen content in the water when they die. The negative impacts of HABs make understanding the physical, chemical, and biological variables influencing the growth of the phytoplankton community a scientific priority. And that’s what we are trying to do here in the lab. This posting has a special focus on one of the local Los Angeles HAB superstars, Pseudo-nitzschia, a diatom that contributes to HABs in the Southern California Bight.
HAB Background – Toxic Blooms and Pseudonitzschia australis
Pseudonitzschia australis, a local diatom, is one of the HAB species here in Southern California. Diatoms are unicellular phytoplankton that have a cell wall made of silica, the same substance that makes up window glass. Diatoms are phytoplankton that often bloom under cool water and nutrient rich conditions. There are an estimated 100,000 species of diatoms that come in a variety of shapes. Interestingly, since the Victorian Age art has even been created from arranging diatoms into intricate patterns (see image above). Pseudo-nitzschia's long narrow shape places it in the pennate diatom group (see image above left).
Domoic acid produced by the diatoms Pseudo-nitzschia causes domoic acid poisoning (DAP) also known as amnesic shellfish poisoning (ASP). DAP poisoning negatively impacts a wide range of wildlife including mussels, crabs, marine mammals, cormorants, and pelicans. Blooms of Pseudo-nitzschia can be expansive with a 1991 bloom establishing from
Pseudo-nitzschia is a typical member of the phytoplankton community off the Southern California coast. However, the numbers are typically so low that Pseudo-nitzschia does not present any harmful threats to the ecosystem or human health. When conditions are right Pseudo-nitzschia can bloom and dominate the phytoplankton community. Once these blooms occur domoic acid can often be measured in the water. Our lab is working to better understand the ocean physical dynamics and conditions that lead to blooms, especially the toxic blooms, of Pseudo-nitzschia in our urban ocean. We collaborate closely with the Caron Lab at USC who are working to understand details about the biology and genetics of Pseudo-nitzschia. More about our collaborative group and our approaches to observing the ocean can be found at http://cinaps.usc.edu.
Tuesday, March 23, 2010
This vehicle doesn’t move quickly, only about 0.3 meters/second or about 0.6 knots. So if the speed of the ocean currents are very strong the glider can’t make the path that it’s supposed to fly. Up to now, we haven’t had a problem with this. But, ……. last week our glider started heading south toward San Diego at a speed of 1-2 knots, and we could not do anything to make it turn back. It was pointing north and heading south. The currents stayed high for the entire week. We had to chase the glider down to Carlsbad – we think it was hoping to have spring break in Mexico with all the other USC students. We were able to retrieve the glider before she crossed the border into Mexico, and will put it back out when the currents have subsided a bit.
Saturday, March 20, 2010
We could discuss the more technical aspects of wind stress and wind stress curl and their effects on the upper ocean, or various processes that contribute to divergences in the ocean that result in upwelling of deeper water. But a simplistic explanation is that when the winds blow from the north along the west coast in the northern hemisphere they accelerate the nearsurface currents toward the south and because of the rotation of the earth these equatorward currents tend to veer offshore. As they veer offshore, water needs to come from somewhere to replenish the water that is moving away from the coast. The source of that water is generally from underneath the layer of water that moves offshore, and this water comes to the surface near the coast. Because deeper water is moving upward to the surface near the coast, we refer to the process as upwelling – vertical upward transport of the water (see the schematic below). The deeper water contains nutrients (nitrogen, phosphorus, and silicate) that support the growth of the microscopic plants (phytoplankton) in the ocean when they are exposed to sunlight. As a result when significant upwelling occurs along the coast, we often see a response in the growth of phytoplankton, just like we discussed when there is significant runoff from rain. While rain runoff is conducive the growth of a group phytoplankton called dinoflagellates, upwelling tends to support more conducive to a group of rapidly growing phytoplankton called diatoms.
In general, upwelling is a very positive process in the ocean. The cooler water is important for maintaining the livable climate of coastal California, and other regions of the world. The nutrients support a biologically productive coastal ocean ecosystem that provides California’s abundant sea life. It is also part of the process where the subsurface ocean ventilates to the surface and atmosphere.
We are in the process of seeing rapid phytoplankton growth along the Southern California Coast right now. However, one of the diatom species that is becoming abundant, Pseudonitzschia australis, can produce the neurotoxin domoic acid that can cause significant damage to the hippocampus region of the brain in mammals (including humans) and birds. Marine mammals and birds feed on the fish that consume these phytoplankton and as a result, we often see the effects when these animals show up on the beach. So far we haven’t seen a lot of the toxicity, but we are watching carefully to see if it develops. If you want to follow this, you can go the Harmful Algal Bloom web page maintained by the Southern California Coastal Ocean Observing System (http://www.sccoos.org/data/habs/index.php
Tuesday, March 9, 2010
It rained again this weekend. We are waiting for a good satellite image of the impacts of the event and should have one from today. So far this season 14.66 inches has been recorded at the National Weather Service’s (NWS) LA Downtown site.
One of the recent storms created a clear biological response in the ocean following the storm. As we mentioned in the previous posting on El Nino, runoff brings a lot of nutrients for plants (nitrogen, phosphorus, etc) into the ocean. Just as on land these plant nutrients promote plant growth, but the ocean plants are microscopic phytoplankton. Although microscopic, they are so abundant that they change the color of the water from blue to more greenish. The ocean color sensors on satellites detect these changes and enable us to measure the concentration of chlorophyll from the plants in the ocean. This enables us to measure the response of the upper visible ocean to the nutrient inputs from the rain runoff.
Between February 5 and 8 nearly 3.3 inches of rain was recorded at the downtown NWS site. That’s quite a bit of rain in a relatively short time. As a result there was a significant volume of runoff that went into the ocean. About 1 week after the rain event a significant phytoplankton response was observed from satellite with high concentrations in both Santa Monica Bay and San Pedro Bay south of LA/LB harbor, extending nearly halfway to Catalina Island (~10-12 miles). The two satellite images show the chlorophyll concentration a couple of days prior to the storm (top image) and the concentration about one week after the storm (bottom image). The large increase of chlorophyll between the two images shows the effects of the added nutrients from the runoff on the coastal concentrations of phytoplankton.
One of our research interests is not only that there are “blooms” of phytoplankton, but what species bloom, and under what conditions do they bloom. Some phytoplankton can produce toxins that are harmful to marine life, birds, and to humans if we consume shellfish or other fish that have eaten the toxic phytoplankton. To determine what species of phytoplankton are present we monitor the species of phytoplankton at various piers around southern California. Whether the runoff from land promotes the formation of toxic blooms is one question that we are addressing in our studies of these “harmful” blooms in southern California.
We’ll write more about that in the next installment.
Rainfall information: National Weather Service - http://www.weather.gov/climate/index.php?wfo=lox
Satelliete Images: SCCOOS
1Hammond and Hazelwood, 1972.
Sunday, January 24, 2010
Every few years an El Niño appears with significant consequences to Southern California. El Niño brings heavy rains that can snarl traffic, cause significant mud slides, flooding, etc., as we have seen this last week. The ocean effects are not as immediately noticable, but are nevertheless significant.
This last week we had a major set of storms pass through Southern California. At the USC campus near downtown LA the total rainfall this week was about 4.5 inches. Up in the mountains there was as much as 12 inches in some spots. That’s almost a third of our annual average rainfall (~14 inches/year in LA) – more in one week than we received in the entirety of July 2006 to June 2007 when the total rainfall was ~4 inches.
So what happens to all of this water? If we could collect it all it would help significantly in alleviating our water shortage. As the city developed and began to pave over a lot of the land that had previously absorbed the rainfall, it began to have significant flooding problems due to the non-absorbed water pouring down creeks, streams, and streets. In response, in the 1930s the Army Corps of Engineers began the development of a stormwater drainage system to efficiently drain the excess water from the land to the ocean. As a result, although flooding does occur in some areas, it is not the problem that it would be without this storm drain system. But soon after the rains begin, the stormwater swollen streams start flowing into the ocean. On the west side of LA this occurs primarily through Ballona Creek that drains the west side of the LA into Santa Monica Bay. The Los Angeles, San Gabriel and Santa Ana Rivers drain regions that extend from the San Fernando Valley on the west to San Bernardino and Riverside on the east and these accumulated flows discharge into San Pedro Bay between Los Angeles/Long Beach Harbor and Huntington Beach.
After the clouds cleared we were able to see the ocean with an ocean color sensor on NASA’s Aqua satellite (source: http://www.sccoos.org/data/modis/modis_regions.php?r=3). The image above shows the remote sensing reflectance in the yellow-green part of the color spectrum. The colors indicate the concentration of particles in the water with blue being very low and red being very high. High concentrations of particles, indicated by the red colors, are a good indicator of where the stormwater plumes are located in the ocean. In the image you can see both Santa Monica Bay and San Pedro Bay south of LA/LB Harbor. This image shows that the storm water plumes extend from the mainland nearly to Catalina, stormwater from San Pedro Bay is flowing around Palos Verdes into Santa Monica Bay, and significant runoff was coming from the west side of Catalina Island near Cat Harbor. Of course, other smaller streams along the coast contribute to this runoff plume.
What are the effects of this runoff on the ocean?
Stormwater carries with it a lot of material from the land and drains. As we mentioned in the first blog, the stormwater contains a range of things that result from human activities and natural processes on land.
- Materials that fall on the roadways from our vehicles as the result of routine wear from tires, brakes, etc., and the leaking oil and other motor fluids from poorly maintained vehicles.
- Microbial contamination from agricultural animals, domestic pets, wild
animals, and occasionally human contamination
- Plant nutrients from fertilizers on agricultural land, golf courses, home
gardens, public gardens, etc.
- Other debris such as from the recent forest fires in the San Gabriel mountains
- Unspecified sources some of which we refer to as “midnight disposal, inc.”.
The consequences of these inputs are many:
Stormwater is often toxic to marine organisms very near where it enters the ocean. This toxicity is often due to metals such as zinc that is a component of automobile brake linings. As the stormwater dilutes into the ocean, this toxicity decreases. The microbial contamination, regardless of its origin, is often above the standards from the California Ocean Plan and causes public health agencies to close beaches for in-the-water activities for up to 3 days following a storm. The plant nutrients are the same nutrients that enable photosynthetic algae to grow in the ocean and we expect that after several days we will see blooms of phytoplankton in the stormwater plumes.
NOAA NWS: http://www.cnrfc.noaa.gov/rainfall_data.php
Monday, January 4, 2010
A couple of weeks ago I took my car into the auto repair shop to be serviced. Aside from the routine servicing, it needed new brake rotors and pads, and new tires – all things that wear out serving their functional purpose. When I was paying the bill, the owner Mike and I were discussing these details, and I asked if he knew what happened to all of the pieces of rotors, pads, and tires that wear away onto the streets and freeways. He indicated that he hadn’t really thought about it. A lot of the material that wears off of our cars forms the dust along roadways – some is blown away, and when it rains a good portion of it is washed into the storm drains that lead to streams and rivers that eventually (but not too eventually around LA) discharge into the ocean. Some of the metals in the brake materials and organic material from our tires can be toxic to the marine organisms that encounter ocean water containing runoff from the urban landscape.
That got me thinking about writing this blog. The ocean lives and breathes on a daily basis just like every other organism and ecosystem on earth. It is affected by weather, climate, daily oscillations of tides caused by the sun and moon, and in Southern California by the large population of more than 21 million people living near the coast between Santa Barbara and San Diego. This is one of the largest and most intensive population centers in North America where water is consumed and discharged, fuels are burned, and carbon dioxide and other gases are produced to support we humans. We work, play, eat, sleep, poop, make haste and wastes all within a very narrow area along the coast. We benefit from the ocean and we in turn affect the ocean on a daily basis.
We have been studying the “urban ocean” for about 25 years with the support of many agencies from various levels of government, which we will discuss in future posts. However, the USC Sea Grant Program has facilitated many of our efforts and deserves significant credit for supporting this research before it was popular with the larger national agencies. Our laboratory at the University of Southern California is also part of an ocean observing system for southern California (SCCOOS). As a result we are observing the ocean on a daily basis using satellite sensors, radars that measure surface currents, buoys that monitor the minute-by-minute changes in the ocean at specific sites, underwater robotic vehicles that map out the changes that occur under the surface, and with all that we still grab samples with buckets. A lot of this data shows up in technical documents and scientific papers that may bore many of you. So our intent this blog is to translate these observations into a diary of the life of the “urban” ocean in our backyard, providing you with a perspective on how we are interacting with our local environment
The staff and students in my lab all love to spend time and play in and on the ocean. Our desire is to convey to you our excitement and wonder of how the ocean functions, and in the process also express some concerns, ideas and realities of how we affect and are affected by the dynamic ocean.