Nearshore Attached Algae
Attached Algae
Periphyton biomass index (PBI)
1) Reduce the loading of dissolved inorganic nitrogen, dissolved phosphorus, iron, and other algal nutrients from all sources to meet the 1967-71 mean values for phytoplankton primary productivity and periphyton biomass in the littoral zone. 2)Support actions to reduce the extent and distribution of excessive periphyton (attached) algae in the nearshore (littoral zone) of Lake Tahoe
Indicators measured include: 1) total yearly suspended sediment load (expressed in million metric tonnes/year); and 2) total annual stream flow (expressed in million cubic meters of water). The load for each day at each stream was estimated from multiple regression of measured values.
This Indicator is reported in the following LT Info areas:
Nearshore Attached Algae.JPG
Summary statistics (# observations, mean, median, std. dev.) for periphyton biomass (Chlorophyll a mg / m2) and p-value for trend analysis for change in biomass. Trend analysis combine all routine sites to assess Lake-wide periphyton trends. Where analysis of trend indicated a significant trend, the direction of the trend is indicated. Observations where Lake Elevation >= 6225 ft or where the sampling depth has been submerged for less than 1000 days (< 1000 day) are thought to reflect trend in stalked diatoms and/or filamentous green algae. Observations where lake Lake Elevation <6225 ft or where the depth has been submerged for more than 1000 days (< 1000 day) are thought to be influenced by blue-green algae. Table adapted from (Hackley et al., 2016a).

No Subcategories for this Indicator.

Program Periphyton


UC Davis has monitored periphyton in Lake Tahoe since 2000. Monitoring also occurred between 1982 and 1985 and 1989 to 1993. The primary periphyton monitoring work are regular sampling work referred to “routine” sampling at nine sites annually (the number of locations has varied historically from six to ten). At each location algal biomass (as chlorophyll a) is sampled five times annually from natural rock surfaces at a depth of 0.5 meters below the water level at the time of sampling. A second type of sampling, referred to a “synoptic” monitoring occurs once a year at 40 additional sites. The timing of synoptic monitoring varies annually and is intended to capture biomass at its peak in the spring. The synoptic monitoring includes collection of chlorophyll a at a sub-set of the sites, as well as a rapid assessment method that quantifies a periphyton biomass index (PBI).


Associated Programs data not provided.