Transcript Benthic macroinvertebrates

Benthic macroinvertebrates
They are ___________
 even in the most _________ or
 environmentally extreme lotic
environments contain some
________________ organisms.
 In general: macroinvertebrates refers to
fauna retained by a ___________________.
Exception: many early life stages pass
through this mesh size (mesh 125-250 um)
Macroinvertebrate communities in many
lotic environments consists of several
_________ species, from numerous phyla:
 __________: insects, mites, crayfish
 Molluscs: snails, limpets, mussels, clams
 ___________: segmented worms
 Nematodes: roundworms
 _______________: flatworms
Most stream macroinvertebrate species are
associated with surfaces of the _________
bottom
 bedrock, _________ and finer sediments
 or other stable surfaces (fallen _______,
snags, roots, and submerged or emergent
aquatic vegetation. (Usually not freeswimming)
Collectively called __________________.
 Fundamental ____ in food web between
organic matter resources (leaf litter, algae,
detritus) and ________.
Aquatic insects
Extremely diverse both taxonomically and
_______________.
 Usually the most abundant large organisms
collected in stream benthic samples.
Thirteen __________ in N. America
 five are strictly aquatic
 _________: dragonflys and damselflies
 Plecoptera: stoneflies
 ______________: mayflies
 Trichoptera: caddisflies
 ____________: hellgrammites
Dragonfly, damselfly
Stonefly nymphs
Stonefly predator
Mayfly Larvae
Adult mayfly
Adult caddis fly
Caddis larvae, adult
Caddis larvae and cases
Caddis larvae and cases
Shredders
Problems of living in a stream
How to obtain ____________?
 or how to remain in a _______ position?
 Some lotic species have developed
structures to obtain oxygen from the
atmosphere
 (analogous to ______________)
 Others use temporary storage of an air
bubble (analogous to SCUBA diving)
A few species use __________________
(analogous to vertebrate hemoglobin)
 Many have developed _________ gills for
obtaining oxygen dissolved in water.
Morphological adaptations for existence in
running water




____________ projections along trailing
edges of legs and body to form hydrofoils
that _______ the organism onto the
substratum.
_______________ of body shape to offer
reduced resistance while swimming.
____________ to provide attachment to
smooth surfaces.
Leg and anal ______ to provide
attachment to a variety of surfaces.
Life history diversity and adaptability

Streams are very dynamic
 __________
 spatially
 ____________
 trophically, etc.
Adaptability:
1. Some species are adapted to ___________
streams
 by having ____________ stages that
hatch as they are hydrated when flow
resumes.
2. Closely related species that occupy a
similar trophic function (or level)
 may temporally separate growth and
_________________ within the same
stream reach.
3. ___________ timing of larval __________
(limits _____________ competition by
regulating development of young)
 or ____________ release by adults for mate
attraction (synchronizes reproductive
behavior with the appearance of young at the
time of optimal food availability).
4. Considerable variation in the ______________
cycles to take advantage of resources when
plentiful.
 Some species are
 multivoltine
 ____________
 univoltine
 or may require 2 or 3 years to complete life
cycle (semivoltine)
 Life history of a particular species may vary
over its’ ____________________.
 univoltine in a portion of its’ range
 semivoltine in ________ portion of range.
Feeding techniques
__________: scraping microbes on solid
surfaces.
__________ of CPOM
Collecting or ___________ of drifting FPOM.
Predation
Most benthic invertebrates gain little
nutritive value from __________ until it
has undergone considerable microbial
modification (digest ________)