Benthic macroinvertebrates

1
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)

2

• 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

3

• 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 free-swimming)
• Collectively called __________________.
• Fundamental ____ in food web between organic
  matter resources (leaf litter, algae, detritus)
  and ________.

4
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

5
Dragonfly, damselfly
6
Stonefly nymphs
7
Stonefly predator
8
Mayfly Larvae
9
Adult mayfly
10
Adult caddis fly
11
Caddis larvae, adult
12
Caddis larvae and cases
13
Caddis larvae and cases
14
Shredders
15
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.

16
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.

17
Life history diversity and adaptability

• Streams are very dynamic
• __________
• spatially
• ____________
• trophically, etc.

18

• 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.

19

• 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).

20

• 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.

21
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
  ________)