Knowledge about ecosystems
An ecosystem is a closed system that can be as small or as large as one can imagine. Even a bucket of water evolves over time into a small ecosystem, and Earth itself is a large ecosystem.
It is important to know about ecosystems because all life originates in these systems. An ecosystem is simultaneously very resilient and very fragile; sometimes, even the smallest changes can cause an ecosystem to collapse. The amount of life in an ecosystem is referred to as biodiversity and is measured by the number of plant and animal species. The quantity of plants and animals is called biomass.
In the ocean, there are many different ecosystems, all of which together constitute the vast ecosystem known as the ocean. A whopping 97% of the world's water is in the ocean. Ecosystems in the ocean begin with abiotic factors reaching a level where life can emerge. When this happens, the first life forms are initiated as the sun's rays hit the ocean surface, stimulating the growth of phytoplankton and plants on the seafloor. Phytoplankton forms the basis of the food chain for many animals, including mussels. It also serves as the foundation for zooplankton, tiny crustaceans, which, in turn, become food for larger animals, creating a complex interconnected web until humans, sitting at the top, are responsible for its balance.
We can harvest from ocean ecosystems, and the better these ecosystems are, the more we can harvest. Therefore, it makes sense to take care of ecosystems, and the best way to do so is by choosing fish caught in the most sustainable manner. Sustainable fisheries have a lesser impact on the ecosystem at the bottom of the sea, which is crucial for the creatures living there.
Seaweed and rocks create structures and hiding places for fish and other animals and can be considered as a forest on the sea floor. Eelgrass belts found along our coasts are nurseries for fish fry and, additionally, have enormous potential for storing CO2.
When using bottom-trawling fishing methods, there is a negative impact on the seafloor ecosystem. In the past, it was compared to plowing a field when trawling. However, just as there aren't many animals living in a plowed field on land other than birds, the same happens in the sea when fishing with bottom-trawling gear. There aren't many different types of animals and plants, resulting in a narrower biodiversity, similar to what occurs on land. This narrower biodiversity can be beneficial for certain animals; in the ocean, it is generally shellfish that take over the seabed when fish are absent.It is important that we take care of our ecosystems, show respect for the ocean, as when we do, more life thrives, and with more life, there are more fish that can be harvested from the ecosystem.
Mussels and seaweed are regenerative foods, meaning they improve the marine environment as they grow. Mussels filter water for plankton, removing plankton and allowing sunlight to penetrate deeper into the water. This benefits the attached macroalgae (seaweed), which requires sunlight for photosynthesis. Thus, mussels and seaweed contribute to nutrient removal from the sea, addressing excess nutrients primarily from agricultural and urban runoff. Mussels and seaweed consume from the bottom of the ecosystem, providing a good reason for us to consume more from the lower levels of the ecosystem. Each time a fish eats a smaller fish, there is an energy loss that the ecosystem must compensate for. Looking at ecosystems in our local waters, tuna is the largest predator besides humans.
This means that 200kg of plant plankton is needed to produce 1kg of tuna when considering the entire ecosystem cost. A notable example of a robust ecosystem is found in Øresund, demonstrating the positive effects of fishing with respect for the sea. Bottom-trawling has not been allowed in Øresund since the 1930s, prohibited due to intense shipping traffic. Today, Øresund stands as one of the best examples of how a seabed should look in Denmark. The seabed hosts an abundance of anemones resembling corals, rich plant and animal life, broad biodiversity, and substantial biomass.
This occurs despite the proximity of two major cities releasing significant nutrient loads. The cod population in Øresund is 100 times more productive than in the Kattegat, contributing 46% of all cod larvae in the Kattegat. A strong ecosystem positively impacting other ecosystems serves as an excellent example!
It is crucial to take care of our ecosystems and respect the sea. When we do so, more life thrives, resulting in more fish that can be harvested from the ecosystem.