## 6 Applications to Governance and Ecosystem-Based Management of the Cases Studied [Discussion]  
### Lakes and Inland Water Systems--A Much-Needed Variable for Ecosystem-Based Management  
ECVs play a critical role in ocean governance by providing the necessary data to understand and predict the changes in the ocean's climate, identify the impacts of climate change in the ocean domain and its resources, and inform decision making on how to adapt and manage these changes. Essential Climate Variables related to the aquatic ecosystems biological carbon pump have reached high levels of maturity [55]; however, we see that the same is not true for the corresponding variables of the lakes. Additionally, other variables such as the lake level and water temperature, are reaching high levels of maturity. As an example, not only it is possible to map lakes worldwide [17] but also water occurrence is now available in high resolution [59] and available online ([[https://global-surface-water.appspot.com/map](https://global-surface-water.appspot.com/map)]([https://global-surface-water.appspot.com/map](https://global-surface-water.appspot.com/map)), accessed on 17 May 2024) to create temporal profiles of water occurrence, change and seasonality worldwide. This tool provides worldwide maps that are essential for local and worldwide governance.  
Other ECVs related to lakes are still at a relatively low level of maturity. For example, measurements of ice cover, evaporation, or solar radiation have not been widely used or have not been consistently measured over a long period of time. Additionally, some ECVs such as water quality, have a moderate level of maturity, and there is a good understanding of the methods and techniques used to measure them, but data availability and consistency may be limited.  
In general, the level of maturity for ECVs related to lakes is increasing as more research is conducted and new technologies are developed to monitor and measure these variables. However, there is still a need for more consistent and comprehensive monitoring, as well as for the development of new methods and techniques to improve the measurement and understanding of these variables.  
Very High-Resolution satellite data could be highly beneficial for both the monitoring of very small lakes and small MPAs. Applications are many, for example Harmful Algal Blooms from cyanobacteria have been possible in a relatively small area of Lake Erie, even constructing a 20-year timeseries based on data from the SeaWiFS sensor [41]. This study showed that blooms from cyanobacteria became longer and longer lasting in recent years and accelerating after 2010 (it includes data until 2018). In another study, lakes across the US with frequent cyanobacterial algal blooms have been quantified based on satellite monitoring [60]. Another example is the Science and Policy Integration for Coastal Systems Assessment (SPICOSA) project [61] aimed at integrating data from ocean colour in coastal zones with the participation of different stakeholders. In the case of very small lakes, due to their value in different local communities, similar projects would be highly beneficial.  
Although these are important examples, they do not apply to very small lakes and effective analysis of algae phenology is only possible when a long timeseries is freely available. Having long term analyses is paramount to better understand changing patterns in algal phenology due to climate variability [15] or specific algal events. For example, in Botswana, a landscape-wide cyanobacteria bloom might have been the root cause of one of the most severe elephant population die-off [40]. The authors clearly state how current resolutions limit the satellites that can be used in these studies.  
In summary, while some Essential Climate Variables related to lakes have a relatively high level of maturity, many of them are still at a relatively low level of maturity, and more research and development is needed to improve their measurement and understanding.