Early warning system to prohibit fish kill by toxic algae blooms.
(bbe fluorometers aquaculture application example)
The bbe FluoroProbe is a reliable instrument for the determination of the algae composition in the water.
Norway’s salmon industry hit the headlines in May 2019, when large toxic algae blooms of the common algae Chrysochromulina leadbeateri killed around 8 million fishes in ocean fish farm nets. The same species of algae was linked to salmon deaths in Norway in 1991 and again in 2008.
The aquaculture sector in Northern Norway is being hit hard by an algae bloom, according to a 16 May statement from Norway’s Directorate of Fisheries.
The algae bloom affected the waters between Nordland and South of Troms, an area of about 450 kilometers -coastline. Algal blooms are caused by phytoplankton, free-floating micro algae subsisting in -marine and freshwater ecosystems.
Algae are the base of the aquatic food chain. The essential nutrient for filter-feeding zooplankton, bivalve shellfish, larvae of commercially important crustaceans, and finfishes.
Harmful algae blooms (HAB) may kill fish in several ways. For example, a densely concentrated algal bloom can deplete oxygen in the water due to the high respiration rate of the algae, or by toxins released by cyanobacteria during their decay.
In water, the concentrations of algae are strongly depth depending. Especially cyanobacteria (blue-green algae) have often a peak at the thermocline.
The blooming peak, of the fish kill event 2019, was in a depth of 18m
The depth profiling bbe FluoroProbe has been used for measuring the algae classification in a fish farming cage in North of Norway in Ofotfjord.
pic: Fish farming north of Norway
The highly sensitive bbe FluoroProbe determines depth depending on the algae classes by analysis of chlorophyll. Many profiles during the field campaign are taken and green algae, blue-green algae/cyanobacteria, diatoms/dinoflagellates, and cryptophytes could be measured.
All vertical profile shows the high algae peak in depths between 10 to 18 meter. It figured out that taking samples only from the surface of the water cannot be a good indicator for monitoring the algae bloom in the water. The in-situ results from the bbe FluoroProbe reduce the time consumption of laboratory tests.
pic: preparation of a depth profile with the bbe FluoroProbe
The bbe FluoroProbe can quickly and reliably determine the chlorophyll content of different algae classes down to a depth of 100m (optionally 1000 m). The measurement data can be displayed in real-time on a PC or be stored in the probe for subsequent evaluation.
In some applications, the online data of the bbe FluoroProbe was transferred via Bluetooth to the local data centre or in a cloud data system. This powerful tool for aquaculture monitoring allows the operator to predict and react at an early stage of a potentially toxic algae bloom. The loss of millions of dollars could get prevented by the investors.
For permanent installation, a salt-resistant titanium version of the bbe FluoroProbe allows long-term monitoring of the algae composition over the year.