SIMoN
  Sanctuary Integrated Monitoring Network
Monitoring Project

Monterey Bay Aquarium Incoming Seawater Monitoring

Principal Investigator(s)

  • Roger Phillips
    Monterey Bay Aquarium
  • Eric Kingsley
    Monterey Bay Aquarium
Start Date: June 13, 1995

The Monterey Bay Aquarium’s (MBA) seawater intake is located about 1,000ft offshore at a depth of ~50ft. Seawater flows by gravity into the Pump House sump, water from which is pumped to all exhibits at the aquarium.

As part of MBA's ongoing water quality program incoming seawater is monitored with both spot measurements and continuously on a 5min interval using in situ sensor technology. Both seasonal events, such as upwelling, and periodic events, such as El Niño are visible in the data record.

Summary to Date

The water quality of incoming seawater is frequently used as a basis of comparison for other exhibits or systems. Both seasonal trends, such as upwelling, and periodic events, such as El Niño are present in the data.

Monitoring Trends

  • Continuous measurements show that during certain seasons, a direct relationship exists between water temperature and dissolved oxygen levels in seawater pumped into our facility – as temperature declines, oxygen saturation also declines. Since cold water can hold more dissolved gas, the observed relationship is not what one would expect based on water temperature. Due to the location of our intake structure in relation to the thermocline, seawater temperature and oxygen content can vary widely on a 24-hour basis. This variability is often associated with upwelling events. An illustration of this relationship can be found in the MBA Continuous Data Daily Averaged Temperature and Dissolved Oxygen vs. Time (April - July 2003) Plot file that is included with this project.
  • Spot measurements of nutrients often show seasonal effects of upwelling. Higher levels of nutrients observed in seawater are generally associated with waters coming from below the thermocline. Or in the case of our incoming seawater are associated with periods of upwelling. An illustration of these seasonal effects can be found in the MBA Spot Check Monthly Averaged Data vs. Time Plots files that are included with this project (Monthly averaged plots of data for total ammonia, nitrite, nitrate, phosphate, dissolved oxygen, and pH are included with this project).
  • An extended warm water period, or El Niño, occurred along the West Coast of North America during 1997 and 1998. Continuous measurements showed above average seawater temperatures beginning in July 1997 and persisting through March 1998. Daily mean seawater temperatures of 17oC or slightly higher were recorded once or twice per month in October and November 1997. Seawater temperatures were often above “normal” through mid-October 1998. See the MBA Continuous Data Daily Averaged Temperature vs. Time files included with this project to view this trend (Plots for the time periods 1995-1998, 1999-2002, 2003-2006, 2007- Current are included with this project).
  • Spot measurements for nitrate and, to a lesser extent, total ammonia concentrations were influenced by an El Niño event that began in July 1997 and extended through September 1998. While not drastically different, lower total ammonia levels were measured during 1998 than in 1997 and 1999. Nitrate concentrations declined in July 1997 and were quite low through October 1998, reflecting El Niño conditions. These conditions can be found in the MBA Spot Check Monthly Averaged Data vs. Time Plots files that are included with this project (Monthly averaged plots of data for total ammonia, nitrite, nitrate, phosphate, dissolved oxygen, and pH are included with this project).

Discussion

While the incoming water to the aquarium is drawn for a depth of ~50ft continuous measurements and spot checks are sampled from either inside the pump house or from piping just inside the building. Consequently occasional sampling artifacts can be found in the data.

Study Parameters

  • Temperature
  • Nitrates
  • Nitrites
  • Phosphate
  • Total ammonia (NH4 + NH3)
  • pH
  • Dissolved oxygen

Study Methods

Dissolved oxygen in spot samples are determined using either a portable polargraphic oxygen probe manufactured by Oxyguard or a portable luminescent dissolved oxygen sensor manufactured by Hach. Oxyguard Gamma, Oxyguard MKIII, or HQ20 Hach Portable LDO Dissolved Oxygen/pH Meters are used for spot measurements. Dissolved oxygen is measured continuously in the incoming seawater line using an Oxyguard Stationary polargraphic oxygen probe.

Nitrate has been analyzed by two different methods, only one of which is currently being used. The current method is a spectrophotometric technique adapted from Johnson, K. S. and L. J. Coletti. 2002 [In situ ultraviolet spectrophotometry for high resolution and long-term monitoring of nitrate, bromide, and bisulfide in the ocean. Deep-Sea Research I 49: 1291-1305]. Nitrate has also been historically determined with a single wavelength ultraviolet spectroscopic absorption procedure adapted from Clesceri, L. S., A. E. Greenburg, and A. D. Eaton. 1998. [Standard Methods For the Examination of Water and Wastewater, 20th Edition. American Public Health Association, Washington, D. C.].

Temperature is measured continuously in the Pump House sump using a Weed Instruments 100ohm, platinum RTD probe.

Temperature and pH in spot samples are measured using either a Corning Model 313 or Model 315 pH/Temp Meter equipped with a "3-in-1" electrode or Hach Model HQ20 Portable LDO Dissolved Oxygen/pH Meter equipped with a Platinum Series pH Electrode.

Total ammonia, nitrite, and phosphate in spot samples are determined spectrophotometrically using methods adapated from Grasshoff, K. 1976. [Methods of Seawater Analysis. Verlag Chemie, New York. 317 p].

Documents

  • MBA Spot Check Monthly Averaged Total Ammonia Data vs. Time Plots
    Multiple plots of the total ammonia (NH4+ + NH3) spot check data vs. time, for the period 1995 – present as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages contains a 10- year period of the data, with the monthly mean ± standard error of the spot checks being presented. Total ammonia (NH4+ + NH3) was analyzed using the method outlined with this project. Both short-term seasonal changes and longer- term events, such as El Niño, are present in the data.
  • MBA Spot Check Monthly Averaged Nitrite Data vs. Time Plots
    Multiple plots of the nitrite spot check data vs. time, for the period 1995 – present as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages contains a 10-year period of the data, with the monthly mean ± standard error of the spot checks being presented. Nitrite was analyzed using the method outlined with this project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.
  • MBA Spot Check Monthly Averaged Nitrate Data vs. Time Plots
    Multiple plots of the nitrate spot check data vs. time, for the period 1995 – present as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages contains a 10-year period of the data, with the monthly mean ± standard error of the spot checks being presented. In the plots that follow those points designated 'MLML Nitrate' were analyzed using the method adapted from Johnson and Coletti 2002 as outlined in this project. Those points designated 'UV Nitrate' were analyzed using the method adapted from Clesceri et. al 1989 as outlined in this project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.
  • MBA Spot Check Monthly Averaged Phosphate Data vs. Time Plots
    Multiple plots of the phosphate spot check data vs. time, for the period 1995 – present as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages contains a 10-year period of the data, with the monthly mean ± standard error of the spot checks being presented. The phosphate was analyzed using the method outlined with this project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.
  • MBA Spot Check Monthly Averaged Dissolved Oxygen Data vs. Time Plots
    Multiple plots of the dissolved oxygen spot check data vs. time, for the period 1995 – present as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages contains a 10- year period of the data, with the monthly mean ± standard error of the spot checks being presented. The dissolved oxygen was analyzed using the methods outlined with this project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.
  • MBA Spot Check Monthly Averaged Temperature Data vs. Time Plots
    Multiple plots of the temperature spot check data vs. time, for the period 1995 – present as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages contains a 10-year period of the data, with the monthly mean ± standard error of the spot checks being presented. The temperature was analyzed using the method outlined with this project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.
  • MBA Spot Check Monthly Averaged pH Data vs. Time Plots
    Multiple plots of the pH spot check data vs. time, for the period 1995 – present as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages contains a 10-year period of the data, with the monthly mean ± standard error of the spot checks being presented. The pH was analyzed using the method outlined with this project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.
  • MBA Continuous Data Daily Averaged Temp vs Time (1995-1998)
    Multiple plots of the daily averaged temperature data vs. time, for the period 1995 – 1998 as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages shows a 2-year period of the data, with the temperature expressed in oC measured using the method outlined with the project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.
  • MBA Continuous Data Daily Averaged Temp vs Time (1999-2002)
    Multiple plots of the daily averaged temperature data vs. time, for the period 1999 – 2002 as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages shows a 2-year period of the data, with the temperature expressed in oC using the method outlined with this project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.
  • MBA Continuous Data Daily Averaged Temp vs Time (2003-2006)
    Multiple plots of the daily averaged temperature data vs. time, for the period 2003 – 2006 as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages shows a 2-year period of the data, with the temperature expressed in oC using the method outlined with this project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.
  • MBA Continuous Data Daily Averaged Temp vs Time (2007-current)
    Multiple plots of the daily averaged temperature data vs. time, for the period 2007 – 2010 as measured in the incoming water to the Monterey Bay Aquarium drawn from a ~50ft depth. Each of the following pages shows a 2-year period of the data, with the temperature expressed in oC using the method outlined with this project. Both short-term seasonal changes and longer-term events, such as El Niño, are present in the data.