Hot, Warm, Cool, Cold: What Temperature Changes Mean for Farmers.

At first glance the ocean surface can look like an empty and unvarying expanse of blue, but take a look below and there is a dynamic three dimensional environment full of life. The same as on land, life underwater is distributed according to environmental conditions. We find corals in place with lots of sun, clear waters, and warm temperatures and we find schools of anchovies in cooler, nutrient-rich waters where their food, plankton, flourish. A big factor in the distribution of these species is the water temperature itself. Water temperature varies based not only on your location North or South of the equator, but also the prevailing currents, the time of year, and the water depth. As a result there are relatively large changes in the ocean’s water temperature as we move around and as the seasons change, this creates a lot of variation in that expanse of blue that we see from the surface.

We don’t usually talk about weather when we refer to conditions below the surface of the ocean, but just like how the daily weather dictates what we wear when we leave the house, life in the ocean is also controlled by the local environmental conditions. Unlike air, water temperature does not change rapidly due to water’s high heat capacity. It takes a lot of energy to warm up or cool down water due to the unique chemistry of hydrogen dioxide. This makes the “weather” below the ocean look a little different then what we experience on land, but just like air, water heats up when the sun shines on it, and in many locations the ocean temperature near shore can vary 10°C between the winter and summer.

There can be large temperature differences between the Atlantic and Pacific side of Central America during certain seasons, this is mostly due to differences in ocean currents and not the air temperature above the ocean.

Temperature variations are important for all aquaculture. Regardless if you are a fish, shellfish, or seaweed farmer you are growing a cold-blooded species that depends on the ambient water temperature to dictate a number of fundamental metabolic processes. Each species has its own unique optimum temperature for ideal health and growth. A fish can still live a comfortable life having never experienced this optimal temperature but there’s still a narrow band of water temperatures where that species will truly thrive. Unfortunately for ocean farmers that magic spot where the temperature conditions are just right most likely occurs only sporadically or sometimes never. Nonetheless we do everything we can to provide that ideal environment. This typically means finding a good farm location where the water temperature is neither too cold nor too hot for the target species. A location with good water flow and exposure to the ocean will typically have a more stable temperature. Locations inside bays or near river mouths may experience more dramatic temperature changes and should be avoided for some species. Outside of locating the farm in the correct spot there is not much a farmer can do to control the temperature, they are at the whim of mother nature. Heating or cooling the water is cost prohibitive due to the amount of energy that would be continuously required. So why care about the ocean’s temperature if there is nothing we can do to control it?

We may not be able to control the water’s temperature but we can still control other factors. Temperature dictates the daily decision-making of farmers. It determines the best time to stock or harvest fish, it also controls fish appetite and the amount of feed we should provide each day. When temperatures are too high we can reduce stocking densities, provide additional health treatments, or change feeding patterns in order to help improve the welfare of the fish. All of these decisions can help improve fish survival and growth rates, but we cannot make the best choice unless we first know the current and ideally the future water temperature.

Climate change is creating challenges for farmers around the world. Locations that once had predictable minimum and maximum temperatures are now exceeding those minimums and maximums on a regular basis. It is not an option to just pick up and move a farm to a new location. Tracking temperature and actively changing the farm’s operations will be crucial to adapting to climate change. Operations can be modified to mitigate some of these challenges such as early harvests or later stocking. How we adapt to temperature changes will control future worldwide aquaculture production.

Water temperature influences fish, shellfish, and seaweeds stress levels and overall health, it also influences when they mature and their behavior, it is too important to be estimated or ignored. Pulse is a new tool for farmer’s to monitor water temperature among other important water quality parameters in the area around their farm. It provides forecasts as well as historical data so farmers can better visualize and understand trends and patterns in water quality. Soon Pulse will be available as a mobile application, making it easier for farmers to check it regardless of where they are. It is time to monitor the ocean the same way we monitor the weather.

Sign up and try Pulse for free by visiting www.pulse.umitron.com