Micronekton

Oplophoridae

Abraliopsis sp

Lanternfish - Hygophum hygomii

Hatchetfish - Argyropelecus aculeatus

Micronekton distribtion during the day and night

Micronekton are a diverse group of marine organisms that inhabit the pelagic zone of oceans and seas. Unlike plankton, which are unable to swim against ocean currents, micronekton possess the ability to swim and thus have some control over their movements in the water column. This category includes a wide range of small to medium-sized aquatic animals such as small fish, squid, crustaceans, and jellyfish. Typically, micronekton are defined as organisms with an adult body size ranging from 2 to 20 centimeters. They play a crucial role in the marine food web, serving as a bridge between the smaller plankton and the larger nekton or apex predators.

Characteristics

Micronekton are characterized by their size and their nektonic behavior, which allows them to swim actively in the water column. This ability distinguishes them from planktonic organisms, which are primarily at the mercy of ocean currents for their horizontal movement. Micronekton are capable of vertical migration, often moving up and down the water column in a daily cycle known as diel vertical migration. This behavior is thought to be a response to predation pressure and changes in light intensity, allowing micronekton to feed in the nutrient-rich surface waters at night and retreat to the safety of deeper waters during the day.

Ecological Importance

Micronekton play a vital role in oceanic ecosystems. They are an essential link in the marine food chain, feeding on smaller plankton and, in turn, being preyed upon by larger marine animals such as fish, marine mammals, and sea birds. This makes them critical to the transfer of energy from the lower levels of the food web to the higher trophic levels. Additionally, through their daily vertical migrations, micronekton contribute to the biological pump, a process by which carbon is transported from the surface waters to the deep ocean, playing a role in the global carbon cycle and potentially affecting climate change.

Types of Micronekton

The micronekton community is highly diverse, encompassing a variety of taxa, including:

- Crustaceans: Such as krill, small shrimp, and copepods that have reached a larger size. - Fish: Small species and juveniles of larger species that can actively swim in the pelagic zone. - Cephalopods: Including small squid and octopuses that are capable of swimming. - Gelatinous zooplankton: Such as jellyfish and salps, which can also swim but are often more buoyant than other micronekton.

Research and Conservation

Studying micronekton is essential for understanding marine ecosystems and the health of the oceans. They are indicators of ocean health and biodiversity. However, researching these organisms poses challenges due to their small size and the vastness of their habitat. Conservation efforts are crucial to protect micronekton from threats such as overfishing, habitat destruction, and climate change, which can disrupt their populations and, by extension, the broader marine food web.