STRAITS POND MIDGES: Biology, Ecology, and Problem Populations

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STRAITS POND MIDGESBiology, Ecology, and
Problem Populations
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Straits Pond inhabitants

• Anadromous/Catadromous/ Amphidromous fish
• Migratory shorebirds and waterfowl
• Invasive plants and animals
• Ailanthus altissima
• Phragmites australis
• Swans

Three-Spined Stickleback
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Invasive plants
Tree of Heaven Ailanthus altissima
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Invasive species
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Straits Pond invertebrates

• Aquatic beetles
• Dragon/Damselflies
• Familiar Bluet
• Big Bluet ?
• Seaside Dragonlet
• Needhams Skimmer ?
• Periwinkle Littorina sp.
• Green Crab C. meanus

Uvarus sp.
COLEOPTERA DYTISCIDAE
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Skimmer Dragonfly Larva ODONATA LIBELLULIDAE
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Straits Pond invertebrates

• Flies (Diptera)
• No-see-ums (Ceratopogonidae)
• Greenheads (Tabanidae)
• Craneflies (Tipulidae)
• Midges (Chironomidae)

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MIDGES

• Abundant and ubiquitous
• Inhabit all aquatic habitats
• Adults do not bite
• Significant food source for many other species
• Pollution-tolerant

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Midge Taxonomy

• Insect order Diptera, or True Flies
• Family Chironomidae
• 20,000 species
• gt350 sub-families
• gt2,000 spp in N.A.

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Aquatic dipteran larvae
Merritt Cummins, 1996 Aquatic Insects of N.
America
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GENUS Chironomus

• Multivoltine - produce 1 to 4 generations each
  year
• Larvae are detritivores
• Larvae burrow, build U-shaped tubes
• Protection
• Respiration
• Body fluids contain high-affinity hemoglobin

C. decorus C. riparius C. plumosus C.
dorsalis gt20 spp. in N.A.
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Chironomus life cycle

• Eggs hatch within 3 days
• Larvae live 5 - 50 days
• Temperature
• Food availability
• Depth preferences
• Overwinter in bottom sediments in mid-larval
  stages

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Chironomus larval ecology

• Associated with soft upper sediment layers
• Densities correlated with organic content
• Consume bacterial and fungal components
• Lower densities found in gravel (ponds)
• Relatively drought and freeze tolerant
• Do not migrate during dry/cold spells

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Pupal stage
www.first-nature.com

• Brief - 2 to 5 days
• Remain in larval tube
• Float to surface before emergence

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Pupal stage
Merritt Cummins, 1996 Aquatic Insects of N.
America
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Adult stage
www.first-nature.com

• Adults live a few days to weeks
• Feed on nectar, or do not feed
• Females produce one batch of eggs

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Adult stage
Merritt Cummins, 1996 Aquatic Insects of N.
America
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Super Floss Chironomid
Courtesy of Washington Fly Fishing
Gallery www.washingtonflyfishing.com
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Factors contributing toproblem populations

• Stagnation
• Warmer temperatures
• Lower Dissolved Oxygen concentration
• Nutrient loading
• Septic systems and fertilizers N, P, K
• Decayed algae and plants C

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Problems Suggestions

• Annoying swarms gather in backyards
• Adult midges are attracted to lights
• Food is abundant
• Larvae thrive in harsh environments

• Beware of bug-zappers
• Attract more insects
• Kill beneficial spp.
• Use yellow bulbs
• Reduce nutrient sources
• Lawns/Septic systems
• Decaying plant material
• Circulate/aerate water

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Alternative control methods

• Manual removal of detritus
• Bacterial breakdown of organic sediments

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Alternative control methods

• Wind or solar powered water aeration
• Introduce predators
• Dragonfly larvae?
• Bream

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Estimated percentages of aquatic invertebrate taxa
Figure 1. Freshwater streams
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Estimated percentages of aquatic invertebrate taxa
Figure 2. Tidal ponds
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Midge Predators

• Fish
• Feed on aquatic stages
• Most effective predators
• Waterfowl
• Feed on aquatic stages

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Midge Predators

• Dragons and Damsels
• Consume all stages
• Charismatic
• Diving Beetles
• Voracious consumers of aquatic stages
• Tolerant, prolific
• Microorganisms
• Fungi, Bti

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Seaside Dragonlet
Erythrodiplax berenice
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Needhams Skimmer
Libellula needhami
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Midge Predators

• Swallows and Swifts
• Forage on mating swarms
• Bats
• Feed in open areas

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Looking ahead

• Monitor beneficial organisms
• Vertebrates
• Invertebrates
• Promote scientific research
• Local schools
• UMass Boston (Biology, ECOS)?
• Adapt