»Aquatic Macroinvertebrate Monitoring
Parks: All MIDN parks
Vital signs:
Aquatic macroinvertebrates
Justification:
Aquatic macroinvertebrates are a vital component of all healthy stream ecosystems. They are instrumental in nutrient and carbon dynamics and are themselves an important link in stream food webs (Webster 1983). Moreover, unlike fish and periphyton (i.e., benthic algae), aquatic macroinvertebrate assemblages are both productive and diverse in virtually all undisturbed streams with permanent flow (Lenat, Smock and Penrose 1980). This is an important consideration in MIDN because many of the smaller tributary streams of component parks (particularly SHEN) have gradients and natural barriers that impede the movement of fish, as well as canopies that restrict light and consequently limit algal productivity. As a result, fish and periphyton assemblages are often represented by very few species even in undisturbed streams.
Other advantages of using benthic macroinvertebrate assemblages to monitor streams include: 1) they are good indicators of local conditions because most benthic species are either sessile or have limited migration patterns through their aquatic phases; 2) they exhibit wide variation in tolerance among species and life stages to environmental stresses; 3) many species have long life cycles relative to other groups which allows inference regarding temporal trends; and 4) sampling aquatic macroinvertebrate assemblages is relatively easy and inexpensive, and has minimal effects on resident biota (Barbour et al. 1999 and Selected References therein; Rosenberg and Resh 1992). In addition, because aquatic macroinvertebrates have been by far the most commonly used group for biological monitoring of aquatic habitats in North America, a large suite of aquatic macroinvertebrate summary metrics have been evaluated with respect to natural variation and responses to numerous sources of degradation (Rosenberg and Resh 1992).
Monitoring objectives:
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Document the status of and trends in the structure and composition of aquatic macroinvertebrates.
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Determine trends in macroinvertebrate communities in relation to changes in water quality and quantity.
Protocol status: In development