**7. Societal benefits of ocean color approaches to algorithm development for key phytoplankton functional types: Fisheries and habs applications**

A fundamental goal of phytoplankton biogeography is to describe how PFTs are distributed spatially and temporally and how these patterns relate to processes that control primary

Ocean Color Remote Sensing of Phytoplankton Functional Types 117

Ocean Color satellites have had a valuable application for many marine biological processes such as red tides and harmful algal blooms (HABs, reviewed in Stumpf & Tomlinson 2005). HABs are not only harmful to the marine ecosystem but substantive economic losses occur in coastal regions worldwide and the need for remote detection of blooms is critical (Anderson et al. 1997, Schofield et al. 1999, Sellner et al. 2003). HAB events threaten human health, living marine resources, and ecosystem health. Their occurrence has increased in frequency, duration, and severity over the last several decades (Figure 9). Current monitoring efforts of toxic cells and toxin levels in shellfish tissue are relatively slow and lack the synoptic coverage of satellites (Schofield et al. 1999). Nevertheless, HAB monitoring can occur at unprecedented scales with detailed shipboard and drifters to predict arrival, transport time, and possibly toxicity of the bloom (Figure 9, Schofield et al. 1999). Knowledge such as this allows the public to know location, timing of the bloom and close any fisheries that are impacted economically. An excellent example of this type work has been conducted on the mesoscale blooms of *Karenia brevis* in the Gulf of Mexico with ocean color derived chlorophyll a and solar stimulated fluorescence (Stumpf et al. 2003, Hu et al. 2005, Figure 9). Most HAB studies have focused on monitoring with chlorophyll-a as a biomass indicator, however, photo-protective pigments such UV mycosporine-like amino acids and gyroxanthin from other non-toxic organisms (Kahru & Mitchell 1998, Moisan et al. 2011). Several countries all over the world have successfully monitored HABs over broad spatial scales with supplemented satellite imagery and aircraft monitoring in the Gulf of Mexico that allows for tracking of the bloom by satellite and drifters to notify the public.

Fig. 9. Left figure: Harmful algal bloom image in the Gulf of Mexico while using drifters and ocean color satellite imagery that allows for tracking for responses to the public (Lohrenz et al., unpub.). Right figure: Fluorescence Line Height is a better indicator than the satellitebased Chl for chlrophyll-a biomass in CDOM-rich waters. This image is for a *Karenia brevis* bloom (modified from Hu et al. 2005, Courtesy of Dr. Chuanmin Hu). Please note that

Over the past few decades, the dominant phytoplankton biomass product, chlorophyll-a, has been observed over a long time period on global scales. Recent investigations using ecological provinces have indicated additional regional variability and have provided

**8. Future directions of algorithm development using ocean color** 

images from different years.

**b. Monitoring and tracking through the identification of harmful algal blooms** 

production/new production. Several theories have been postulated about what governs biological diversity, which stabilizes community dynamics. Future satellites with increased spectral resolution will allow for algorithms of different proxies for diversity whether the products are pigments, size spectra, or biogeochemical indicators. Such phytoplankton diversity indicators will lead to a better understanding of the response of marine ecosystems to climate and human activities (Platt et al. 2008, 2009). To date, the scientific community has been able to describe phytoplankton community structure based on broad size classes, pigmentation, probability of occurrence, or some other index of presence or absence. We have focused on two successful applications including fisheries management and harmful algal blooms.

### **a. Fisheries applications**

Satellite ocean color application on broad scales allow for PFTs, namely diatoms, to be put into an ecological context regarding El Niño events in the Humboldt ecosystem (Jackson et al. 2011, Figure 8). A locally tuned algorithm for detecting diatom distribution allowed for critical observations in shifts in the size structure of the phytoplankton community, which provide a food source for anchovies. Changes in carbon structure will affect food stress on the fish populations and appears to influence landings in the following year. Mapping the distribution and abundance of phytoplankton using remotely sensed data assists in the creation of targeted and quantitative fishing strategies. Satellites can provide strategies and tools together with modeling and other satellite. Both ocean color and other satellite data, coupled with models, can provide resource managers the information of food web components (other than the chlorophyll-a product), which may be used to direct shipboard sampling on regional scales.

Fig. 8. Climate-induced changes in the spatial distribution of diatoms in the Humboldt system. The figure shows a marked reduction in the presence of diatoms during the 1997 El Niño event compared with the control period (December 2000), which represents typical oceanic conditions for the study region. The color bar represents the fraction of pixels identified as diatoms. Modified from Jackson et al. (2011).

production/new production. Several theories have been postulated about what governs biological diversity, which stabilizes community dynamics. Future satellites with increased spectral resolution will allow for algorithms of different proxies for diversity whether the products are pigments, size spectra, or biogeochemical indicators. Such phytoplankton diversity indicators will lead to a better understanding of the response of marine ecosystems to climate and human activities (Platt et al. 2008, 2009). To date, the scientific community has been able to describe phytoplankton community structure based on broad size classes, pigmentation, probability of occurrence, or some other index of presence or absence. We have focused on two successful applications including fisheries management and harmful

Satellite ocean color application on broad scales allow for PFTs, namely diatoms, to be put into an ecological context regarding El Niño events in the Humboldt ecosystem (Jackson et al. 2011, Figure 8). A locally tuned algorithm for detecting diatom distribution allowed for critical observations in shifts in the size structure of the phytoplankton community, which provide a food source for anchovies. Changes in carbon structure will affect food stress on the fish populations and appears to influence landings in the following year. Mapping the distribution and abundance of phytoplankton using remotely sensed data assists in the creation of targeted and quantitative fishing strategies. Satellites can provide strategies and tools together with modeling and other satellite. Both ocean color and other satellite data, coupled with models, can provide resource managers the information of food web components (other than the chlorophyll-a product), which may be used to direct shipboard

Dec 1997 Dec 2000

Fig. 8. Climate-induced changes in the spatial distribution of diatoms in the Humboldt system. The figure shows a marked reduction in the presence of diatoms during the 1997 El Niño event compared with the control period (December 2000), which represents typical oceanic conditions for the study region. The color bar represents the fraction of pixels

identified as diatoms. Modified from Jackson et al. (2011).

algal blooms.

**a. Fisheries applications** 

sampling on regional scales.

#### **b. Monitoring and tracking through the identification of harmful algal blooms**

Ocean Color satellites have had a valuable application for many marine biological processes such as red tides and harmful algal blooms (HABs, reviewed in Stumpf & Tomlinson 2005). HABs are not only harmful to the marine ecosystem but substantive economic losses occur in coastal regions worldwide and the need for remote detection of blooms is critical (Anderson et al. 1997, Schofield et al. 1999, Sellner et al. 2003). HAB events threaten human health, living marine resources, and ecosystem health. Their occurrence has increased in frequency, duration, and severity over the last several decades (Figure 9). Current monitoring efforts of toxic cells and toxin levels in shellfish tissue are relatively slow and lack the synoptic coverage of satellites (Schofield et al. 1999). Nevertheless, HAB monitoring can occur at unprecedented scales with detailed shipboard and drifters to predict arrival, transport time, and possibly toxicity of the bloom (Figure 9, Schofield et al. 1999). Knowledge such as this allows the public to know location, timing of the bloom and close any fisheries that are impacted economically. An excellent example of this type work has been conducted on the mesoscale blooms of *Karenia brevis* in the Gulf of Mexico with ocean color derived chlorophyll a and solar stimulated fluorescence (Stumpf et al. 2003, Hu et al. 2005, Figure 9). Most HAB studies have focused on monitoring with chlorophyll-a as a biomass indicator, however, photo-protective pigments such UV mycosporine-like amino acids and gyroxanthin from other non-toxic organisms (Kahru & Mitchell 1998, Moisan et al. 2011). Several countries all over the world have successfully monitored HABs over broad spatial scales with supplemented satellite imagery and aircraft monitoring in the Gulf of Mexico that allows for tracking of the bloom by satellite and drifters to notify the public.

Fig. 9. Left figure: Harmful algal bloom image in the Gulf of Mexico while using drifters and ocean color satellite imagery that allows for tracking for responses to the public (Lohrenz et al., unpub.). Right figure: Fluorescence Line Height is a better indicator than the satellitebased Chl for chlrophyll-a biomass in CDOM-rich waters. This image is for a *Karenia brevis* bloom (modified from Hu et al. 2005, Courtesy of Dr. Chuanmin Hu). Please note that images from different years.

### **8. Future directions of algorithm development using ocean color**

Over the past few decades, the dominant phytoplankton biomass product, chlorophyll-a, has been observed over a long time period on global scales. Recent investigations using ecological provinces have indicated additional regional variability and have provided

Ocean Color Remote Sensing of Phytoplankton Functional Types 119

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information based on marine ecology and biogeochemistry in the broader context of climate change (Falkowski et al. 2004). Although validated satellite data is not a substitute for shipbased sampling, *in situ* information about the physical/biological regimes is still required to produce sound ecological products. Hence, the future lies in the combined utilization of *in situ* data, remote sensing, and modeling. The remote sensing of PFTs in the ocean will bring about a greater understanding of how phytoplankton community structure affects climate with biologically-produced greenhouse gases. In contrast, PFTs will contribute to an overall understanding of global marine biodiversity and that knowledge will provide insight on the relationship between ecosystem stability and ocean biogeochemistry.
