Relationships Between Habitat Preferences, Feeding, Life Cycles of Aquatic Insects & Stream Health Relationships Between Habitat Preferences, Feeding, Life Cycles of Aquatic Insects & Stream Health

Dr. Robert Bohanan University of Wisconsin - Madison Center for Biology Education [email protected]

Homage to Santa Rosalia or Why are there so many different kinds of animals? G. E. Hutchinson, 1959 “… Vast numbers of Corixidae were living in the water. At first I was rather disappointed because every specimen of the two species present was a female, and so lacking in most critical diagnostic features, while both sexes of the second slightly smaller species were present in about equal number. … The larger C. punctata was clearly at the end of its breeding season, the smaller C. affinis was probably just beginning to breed. This is the sort of observation than any naturalist can and does make all the time. It was not until I asked myself why the larger species should breed first, and then the more general question as to why there should be 2 and not 20 or 200 species of the genus in the pond, that ideas suitable to present to you began to emerge. These ideas prompted the very general question as to why there are such an enormous number of animal species.”

Aquatic Insects Inhabit Virtually Every Possible Freshwater Habitat • What are some of the factors that might explain why insects have been so successful in freshwater?

– Evolutionary history – Morphology – Physiology – Behavior – Development

What living and non-living factors could influence the successful development of an organism from an egg to a sexually reproducing adult in a stream?

How might habitat selection affect the life history of an aquatic insect?

• Substrate for attachment and or shelter • Food availability (quality and quantity) • Range of current • Water temperature and Oxygen • Presence and relative abundance of other organisms • Others?

Stream Order

1 2

Organic Energy Sources

Coarse Particulate Organic Matter 3 4 5 6 7 8 9 10 11 12 Periphyton Fine Particulate Organic Matter Phytoplankton Zooplankton Dissolved Organic Matter

Channel Width Ecological Communities Shredders

Grazers Predators Collectors Microbes

Collectors

Shredders Predators Grazers Microbes

Collectors

Predators Microbes

Table 2. Substrate Type Sand Gravel Pebbles & Cobble Leaves Detritus Abundance (#/m 2 ) 920 1300 2130 3480 5680 Graphic presentation of Table 2.

# of Species 61 82 76 92 66

x o x o x o x o x o

Sand Gravel Pebbles & Cobble Leaves Detritus

Where’s the Mayfly?

Most Aquatic Insects Include a Sexually Mature Winged Adult

Mayfly Instars

Determining Instars

Adaptations?

Strong Swimmers

Burrowing and Clinging

Staying Out of the Current

Common Mayfly Habitat Preferences • Baetidae • Heptageniidae • Caenidae • Slow - Fast Current, Pools-Riffles, Variety of Substrate • Slow-Fast Current, Often in Cobble, Logs, Submersed Vegetation, Leaf Packs • Slower Current, Sediments

• Ephemeridae • Ephemerellidae • Leptohyphidae • Potamanthidae • Isonychidae Rare Mayfly Habitat Preferences • Slower Current, Sand and Silt • Smaller, Cooler Streams, Leaf Packs • Slower Current, Variety of Substrates • Slower Current, Larger Streams, Gravel, Cobble • Faster Current, Variety of Substrate

• Baetidae • Heptageniidae • Caenidae • Ephemeridae • Ephemerellidae • Leptohyphidae • Potamanthidae • Isonychidae

Mayfly Life History

• Often Bivoltine • Mostly Univoltine • Likely Univoltine • Univoltine, some Semivoltine • Univoltine • Univoltine, some Bivoltine/Multi • Univoltine • Bivoltine, some Univoltine

Trichoptera

Living Free

Filter Feeding Using Nets

How do caddisflies share what may be limited resources?

• Habitat selection • Substrate preferences • Resource partitioning – Shredders – Filterers – Collectors – Predators

Portable Cases

Cases that mimic

Using Available Materials

Square Cases

Using Minerals and Organic Materials

Common Caddisfly Habitat Preferences • Hydropsychidae • Limnephilidae • Hydroptilidae • Helicopsychidae • Moderate-Fast Current, Cobble, Gravel, Submersed Vegetation • Slow-Fast Current, Submersed Vegetation, Cobble, Gravel, Sand, Detritus • Variety, Submersed Vegetation • Variety, Sand

Rare Caddisfly Habitat Preferences • Uenoidae • Brachycentridae • Glossosomatidae • Psychomyiidae • Philopotamidae • Phryganeidae • Smaller Streams, Cobble • Often Smaller, Cooler Streams, Submersed Vegetation, Cobble, Gravel • Smaller, Cooler Streams, Cobble • Smaller, Cooler Streams, Cobble, Logs • Small-Large, Cool-Warm, Cobble, Logs • Variety, Slower Current, Submersed Vegetation

• Hydropsychidae • Limnephilidae • Hydroptilidae • Helicopsychidae • Uenoidae • Brachycentridae • Glossosomatidae • Psychomyiidae • Philopotamidae • Phryganeidae Caddisfly Life History • Univoltine, some Bivoltine-Semi • Univoltine • Univoltine, some Bivoltine • Univoltine, some Bivoltine • Likely Univoltine • Semivoltine, some Univoltine • Univoltine • Likely Univoltine • Univoltine • Univoltine

Territoriality and Foraging • Caddisfly larvae include case building species • Larvae scrape algae from the surface of rocks in streams and rivers • What is the relationship of territory size and larval growth?

Why Build Cases?

• Tube-shaped cases appear in Diptera (above) and in Trichoptera (below)

Case building in some insect larvae reduces encounter rates and mortality • Some case building species had reduced encounter frequency than did some non case building species • Lower encounter frequency also resulted in lower mortality of case builders compared to non-case builders

Evolutionarily, why do some species build cases and others not?

• Cases may not be adaptive, may be a byproduct • Cases may be adaptive, but for some species the costs may exceed the benefits • What are some potential costs?

Evolutionary Costs of Case Construction

• Building additional cases increases larval mortality • Building additional cases prolongs larval development • Building additional cases as larvae reduces the number of eggs in adult females