Identifying Aquatic Habitat Features

The aquatic environment presents a much more challenging place for insects to live than do non-aquatic, terrestrial habitats.  Special adaptations for breathing, swimming and eating have evolved to make insects suitable to thrive in their water-oriented conditions.  Though not entirely necessary to our ability to catch fish with flies, an understanding of the basic freshwater environments and their interrelationship with insects is important to our overall knowledge and contributing to our angling success.To link to further details revealing why/how a particular feature is relevant to insectology & fly fishing, click the

Lotic habitats . . . these are habitats of flowing water, i.e., rivers, streams, creeks, brooks  (see "Stream order" for diagram)                                                                                                                    

• perennial streams . . . these are lotic habitats where the water flows continually throughout the year
  

• intermittent streams . . . flows here may discontinue during part of the year

Within lotic habitats are definable "lotic zones":

• erosional zone . . . an area of a stream where water flows fast enough to carry sediment
  

• depositional zone . . . an area of a stream in where the current is relatively slow and sediment settles out 

Lentic habitats . . . refers to standing water, e.g., lakes, ponds, pools, swamps   

• oligotrophic lakes . . . have low levels of nutrients and aquatic vegetation and high levels of dissolved oxygen
  
• eutrophic lakes . . . have an abundance of nutrients, aquatic vegetation and low levels of dissolved oxygen

Within lentic habitats are definable "lentic zones":

• littoral zone . . . the shallow shoreline area extending to the limit of rooted vegetation
• limnetic zone . . . the open water area extending to the depth of light penetration
• profundal zone . . . the open, deep water area below the level of light penetration, including the bottom