Deep-Sea Foodwebs: It’s Complicated
Due to its vast size and depth, the deep-pelagic ocean (200 meters and below) helps maintain the health of the planet by playing a role in carbon sequestration, nutrient cycling and waste absorption, and even supports the production of economically valuable fisheries.
As natural resource extraction and other human stressors expand into deeper depths, our limited understanding of deep-pelagic ecosystems makes implementing effective management strategies difficult.
Current management plans, which take an ecosystem level approach, require a detailed understanding of the structure of food webs. Understanding the architecture of a food web can provide valuable insight into the flow of energy through an ecosystem and allows us to understand the extent to which different species interact through predator-prey relationships. In addition to understanding predator-prey relationships, knowledge of how food web structure changes across space (both horizontally and vertically) is critical.
In the ocean, how animals are spread vertically within the water column is an important variable to consider when describing food web structure. While animals have been found throughout all vertical zones of the ocean, almost all deep-pelagic life is connected through a reliance on primary production at the surface as a source of carbon. Many animals in the deep pelagic access the productive surface waters by ascending each night to feed under the protective cover of darkness, before descending back to deeper depths as the sun rises. This diel vertical migration represents a conduit of energy, connecting communities of organisms inhabiting each of the ocean’s vertical zones. It also adds a layer of complexity to the food web structure of the deep ocean.
While difficult and time consuming to unravel, detailed information regarding food web structure is vital for the construction of effective mathematical models. These models can be used to predict how changing environmental conditions, fisheries, and natural resource extraction will affect deep-pelagic ecosystems.
Continue reading article in the Deep Sea issue [January/February 2019] of ECO magazine by following this link.
Words by Travis Richards, Texas A&M University