Soft Bottom

See the map below to explore the extent of soft bottom habitat in North Carolina. If the map is not displaying properly, view it in a standalone browser window.

Soft bottom habitat occurs wherever there is uncovered, unvegetated sediment in freshwater, estuarine and marine systems. Soft bottom is utilized by nearly every native fish species in North Carolina and is a critical habitat to species of fish that dig or bury themselves in substrate. Soft bottom habitats include places such as mud flats, beaches, shoals, holes and sand bars.

Function of Soft Bottom Habitat

Function of Soft Bottom Habitat

Soft bottom areas store, supply, and recycle sand and sediment for other habitats. The sediment found in soft bottom habitats is constantly moving from one area to another and from one habitat to another. Intertidal flats and sand bars buffer wave energy, reducing shoreline erosion. In addition, soft bottom habitat provides an area for marine animals to burrow, forage and spawn. Soft bottom may change into another habitat type if submerged aquatic vegetation grows or if oysters settle there.

How Fish Use Soft Bottom Habitat

How Fish Use Soft Bottom Habitat

Like the water column, soft bottom is used to some extent by almost all coastal fishes in North Carolina. On shallow intertidal flats planktivores, like anchovy and menhaden, feed on benthic microalgae and organisms that are suspended in the water column by wave action. Many Rays, flatfish, drums, sturgeon and crabs forage in soft bottom sediment for invertebrates. Flounder, sharks, drum and sea trout prey on smaller fish, shrimp and crabs in estuarine soft bottom habitat. Ocean soft bottom, particularly in the surf zone serves as an important foraging ground for pompano, red rum, kingfish, spot, croaker, weakfish, Spanish mackerel and striped bass.

Soft bottom represents an important spawning environment for many fish. In estuarine waters flatfish, clams, drum, spotted sea trout, and blue crabs spawn. In oceanic soft bottom habitat summer flounder gather to spawn during the winter in locations where the tides and currents carry their young into protected estuaries. Nearshore ocean water in North Carolina also serve as important pupping grounds for several species of sharks such as Atlantic sharpnose shark, bonnethead shark, and to a lesser extent blacktip shark and scalloped hammerhead shark. Atlantic and shortnose sturgeon rely on freshwater soft bottom habitat to spawn. Shallow water of intertidal flats and surf zone provides refuge from predators for young and juvenile flounder, spot, croaker, shrimp, and many others. Species such as clams and gobies burrow in soft sediment to escape predation.

Highly Associated Species

Highly Associated Species

  • Croaker
  • Spot
  • Flounder
  • Blue crabs
  • Shrimp
  • Clams
  • Sturgeon
  • Kingfish
  • Rays
  • Sharks
Threats to Soft Bottom Habitat

Threats to Soft Bottom Habitat

  • Habitat disturbance from dredging, filling and fishing gear.
  • Degradation and loss of habitat from construction of docks, jetties and bulkheads.
  • Removal of habitat by excavation mining and beach nourishment.
Important Facts about Soft Bottom Habitat

Important Facts about Soft Bottom Habitat

  • Although soft bottom habitat is defined as “unvegetated” and lacks visible structural habitat, the surface sediments support an abundance of microscopic plants called benthic microalage and numerous burrowing animals are hidden below the surface.