Nekton

Definition

Nekton refers to the group of aquatic animals that are capable of swimming freely and actively moving throughout the water column. This term typically encompasses organisms like fish, squid, and marine mammals that can navigate against currents, making them essential players in the food web and ecosystem dynamics within freshwater and marine environments.

5 Must Know Facts For Your Next Test

1. Nekton are generally larger than plankton and have developed adaptations that allow them to swim efficiently in the water column, such as streamlined bodies and powerful muscles.
2. The presence of nekton plays a critical role in nutrient cycling within aquatic ecosystems, as they often feed on smaller organisms and are preyed upon by larger predators.
3. Nekton can be found in both freshwater and marine environments, including lakes, rivers, oceans, and coastal areas, contributing to biodiversity in these habitats.
4. Some nektonic species, like salmon, exhibit migratory behaviors, traveling great distances between breeding and feeding grounds, which impacts both local ecosystems and human fisheries.
5. In lake zonation, nekton tend to inhabit the open water (pelagic zone) where they can take advantage of various prey species while avoiding bottom-dwelling predators.

Review Questions

• How do nekton differ from plankton in terms of mobility and ecological role within aquatic ecosystems?
  • Nekton differ from plankton primarily in their ability to swim actively against currents, allowing them to occupy different ecological niches. While plankton are primarily passive drifters that serve as the foundation of the food web through photosynthesis and primary consumption, nekton are predators or competitors that impact population dynamics within their ecosystems. Their mobility enables them to traverse vast areas in search of food, thus influencing energy transfer within aquatic communities.
• Discuss how changes in environmental conditions might affect nekton populations in relation to lake zonation.
  • Changes in environmental conditions, such as temperature fluctuations or alterations in nutrient availability, can significantly impact nekton populations. For instance, a rising water temperature may lead to shifts in species distribution as nekton seek cooler waters or alter their feeding patterns. These changes can also affect zonation dynamics; for example, if certain prey species decline due to environmental stressors, nekton may migrate to other zones where food is more abundant. Understanding these relationships is crucial for effective management of aquatic resources.
• Evaluate the implications of human activities on nekton populations and their roles within lake ecosystems.
  • Human activities such as pollution, overfishing, and habitat destruction pose significant threats to nekton populations and their ecological roles. Pollution can lead to habitat degradation and reduced oxygen levels, impacting growth and reproduction rates. Overfishing alters predator-prey dynamics by removing key species from the ecosystem. Additionally, habitat destruction can limit the availability of spawning grounds for migratory nekton. These changes can disrupt energy flow within the food web and ultimately affect overall lake health and biodiversity.

Related terms

plankton: Plankton are microscopic organisms that drift or float in water, unable to swim against currents. They form the base of the aquatic food web and include both phytoplankton (plant-like) and zooplankton (animal-like).

benthic zone:

The benthic zone is the lowest ecological zone in a body of water, consisting of the sediment surface and sub-surface layers. It is inhabited by organisms called benthos, which live on or near the bottom.

thermocline:

The thermocline is a layer in a body of water where temperature changes rapidly with depth, separating warmer surface waters from colder deep waters. This layer can influence the distribution of nekton and other aquatic life.