The Plumes & Blooms Project

The University of California at Santa Barbara conducts a great deal of scientific research in our local waters. Among the universities many projects is an ongoing research program known as the Plumes and Blooms project (PnB project). Organized jointly with the Channel Islands National Marine Sanctuary (CINMS) and the university's Institute for Computational and Earth Systems Science (ICESS) the PnB project provides data on the Santa Barbara Channel's ever changing environment. The project represents an ongoing effort to create a body of data relating to the physical and biological processes that have shaped the channel's marine environment and provide clues as to what changes may occur in the future.

The main emphasis of the PnB project is to understand the cyclical nature and environmental implications of sediment plumes and algal blooms in the Santa Barbara Channel.

What are Sediment Plumes?

Sediment plumes are caused by sediment rich rainwater runoff entering the ocean. The runoff creates a visible pattern of nutrient rich, brown sediment that forms a kind of cloud in the water spreading out from the coastline. From December to March, plumes commonly form at river and stream mouths, near sloughs, and along coasts where a large amount of rain runoff flows directly into the ocean.

What are Algal Blooms?

Sediment plumes are very rich in nutrients meaning that they have a lot of the things that plants need to survive. Nitrogen and phosphorous are two examples of nutrients. On land plants absorb these nutrients from the soil they grow in. In the ocean, microscopic plant like organisms float freely in the water column and absorb the same nutrients directly from the seawater they live in. Scientists classify these tiny plant-like creatures as phytoplankton, but most people call them microalgae.

Phytoplanton are very important to marine ecosystems because they provide the primary energy source for the entire marine food web.

Just like plants and flowers on land, algae grow and shrink with the seasons. During the winter months algae populations are low. Phytoplankton have difficulty surviving in the wintertime because of the low nutrient inputs.

As spring comes the conditions are perfect for a rebound in the phytoplankton population. Increased nutrient concentrations due to coastal upwelling lead to increased abundance of phytoplankton is called the spring bloom and it continues well into the summer. As winter approaches once again Phytoplankton populations dwindle and the seasonal cycle is completed. This seasonal phenomonon is known as the "plumes and blooms" cycle.

The properties of Sea-water and their importance

Many aspects of seawater are studied. Among these aspects are density, temperature, salinity, chlorophyll concentration, particulate level. These water properties can be measured in a number of ways. The method that is used depends on the property being measured. Temperature for instance is the most commonly measured property of seawater, and some may argue the most important. Sea surface temperature was key in discovering and tracking the 1998 El Niño storm phenomenon. Measurements of chlorophyll concentrations can tell scientist if there is an Algal Bloom occurring, and measurement of particulate levels, along with salinity can be helpful in identifying hard to see sediment plumes.

Here are a few brief descriptions of important water properties that are measured by the Plumes and Blooms project

Temperature

The temperature of a water column can give scientists a number of clues about what kinds of organisms might be living in the water column, where the water came from, or how the properties of the water are changing. Temperature is almost always measured by using a device known as a CTD. The CTD measures the temperature of the water column using an electronic temperature sensor. Differences in temperature at various depths can indicate the level of mixing and amount of stratification in a water column.

Salinity

Salinity is another important property of seawater. As with temperature, salinity can give scientists a number of clues about where the water came from. It is not only an indication of how salty the water is but also how many solid particles are in a given amount of water. Salinity is expressed as grams of solids in 1000 grams of seawater. The average ocean salinity is 35. This means that there are, on average, 35 grams of solid matter in every 1000 grams of seawater. Salinity is also measured by the CTD device. The CTD runs a current of electricity through the water and measures the voltage of this current. For water of the same temperature, the higher the salinity the more electrically conductive the water column is. So if the CTD measures a high voltage current the water has a high salinity, and if the voltage is low it has a lower salinity.

Sediment in the ocean

The amount of sediment suspended in a particular body of water, sometimes called the sediment load, is a property that can be measured in a number of different ways. One particularly sensitive measure for the sediment load is Silica concentration in the water column. Scientists measure two types of silica in Plumes and Blooms project, Lithogenic Silica and Biogenic Silica. Lithogenic Silica comes from the land, also called the lithosphere, and Biogenic Silica comes from the shells of marine animals. In the Plumes and Blooms data sets these two attributes are abbreviated as Lsi and Bsi.

Chlorophyll concentrations

Phytophankton pigment biomass can be quantified using the Chlorophyll core. Chlorophyll measurements are done in a number of different ways. One way is to quantify the color of the ocean with a radiometer and relate the color ratio (blue to green light)to the Chlorophyll concentration. The more green light the higher the Chlorophyll concentration. Another method is to collect water samples from specific sites that are of interest to the scientists. Once they have the water samples they want, then they are taken to the laboratory and run through a filtering machine. There are a number of different kinds of filtering processes. Most all of them filter the water through a small disc shaped piece of paper with microscopic holes. When the filtering is complete everything that was in that sample of water is now in the filter paper. This paper is then run through another machine called a fluorometer. The fluorometer shines light through the filtered sample. The amount of light absorbed by the sample can tell the scientist how much chlorophyll is in the sample.