Coastal Margin/NearshoreOpen Water Zone
Scudder D. Mackey, Ph.D.
University of Windsor
Structural Habitat
• Created by the dynamic interaction of geological,
hydrological, and biological processes
• Formed by features and conditions that exhibit an
organizational pattern that persists and are
“repeatable” in a system – elements that are
essential to maintain a renewable resource
Peters and Cross (1992)
• The Lake Erie ecosystem co-evolved and has
adapted to these structural habitats
Fundamentals - Aquatic Habitat
• Combination of a range of physical characteristics
and energy conditions that can be delineated
geographically that meet the needs of a specific
species and/or biological community for a specific life
stage.
• Created and maintained by physical processes
acting along hydrogeomorphic pathways that convey
energy, water, and materials to, and through, the
lakes.
Abiotic (Physical) Characteristics
•
(Climate)
Energy
•
“Habitat”
•
Substrate
Water Mass
(Geology)
(Hydrology)
•
Energy – oscillatory and
unidirectional flows, shear
stress, turbulence.
Substrate – bedrock,
composition, texture,
hardness, stability,
porosity, permeability,
roughness.
Water Mass – depth,
temperature, turbidity,
nutrients, contaminants,
and dissolved oxygen.
Habitat – when physical
characteristics meet the
needs of a specific species
or biological community for
a given life stage
Aquatic Environmental Template
•
•
•
Requires a dynamic classification system
Multiple geospatial data layers
3-Dimensional
What are the
characteristics
or variables that
define habitat?
•Physical attributes
•Biological attributes
•Chemical attributes
Water Mass
Energy
Substrate
Coastal Margin/Nearshore Zones
Original Boundaries
• Shoreward limit:
– High water mark, including the shoreline physical attribute
(e.g., beach, breakwall, bluff, etc.)
• Lakeward limit:
– Western basin - nearer of 5 m depth contour or 4 km
– Central & Eastern basins - nearer of 10 m depth contour or 4
km
• Polygon bounds:
– Centered on 2nd order or larger river mouths; extending halfway to distance to next river mouth on either side
“Nearshore” Zones
Revised Boundaries
• Coastal Margin Zone (Littoral Processes)
– Shoreward limit:
• High water mark, including the shoreline physical attribute
(e.g., beach, breakwall, bluff, etc.)
– Lakeward limit:
• 3 m isobath
• Nearshore/Open Water Zone (Open Water Processes)
– Shoreward limit:
• 3 m isobath
– Lakeward limit:
• 15 m isobath
• Littoral Transport (cells)
• Gyres
• Tributary Zones of Influence
Open Lake/Offshore
Nearshore/Open Water
Coastal Margin
Nearshore/Open Water
“Nearshore” Data
Available Information
• United States:
– Existing surveys of OH nearshore to 4 km
distance;
– Shoreline armoring information (ODNR, USACE
Potential Damages Study)
– QHEI information (OEPA)
– Nature Conservancy Nearshore Classification
• Canada:
– Environmental Sensitivity Atlas information
(1:10,000 shoreline & nearshore bottom features)
– CCIW - Environment Canada (Coakley,
Biberhofer, Rukavina, Minns et al.)
Nearshore Sediment Distribution
Western Lake Erie
Nos70k.shp
Bathy
Bathymetry (meters)
Nearsed
Glacial (Till, Glacial Lake Clay)
Island
Mud
Muddy Sand / Sandy Mud
Rock
Sand
Undefined
0
0
5
N
10
10
15
20
20 Miles
30 Kilometers
Lake Erie Sediment Distribution
N
W
E
S
Sand and Gravel
Mud
Sand and Mud
Bedrock
Cohesive Clay (Glacial Till)
0 10 20 30 40 50 60 70 80 90 100
Kilometers
After Haltuch and Berkman (1999)
Coverages courtesy Canada Centre for Inland Waters, Dr. John P. Coakley
Richards and Bonde (1999)
Richards and Bonde (1999)
Information Required
• Important attributes or variables include:
–
–
–
–
Substrate characteristics (distribution, stability)
Kinetic energy (low, medium, high)
Water mass characteristics (flow/circulation patterns)
Biota-specific habitat variables (function, life stage)
• Dominant processes
– Littoral: Coastal Margin Zone
– Open-Lake: Nearshore/Open-water Zone
• Tributary Influences (mixing zones)
Summary
• Redefined boundaries based on:
• Linkages to dominant processes
• Physical data (photic zone, stratification)
• Biological data (fish and benthic communities)
• Data gaps will drive research/data collection efforts
• Nearshore/Open-Water Zone will be a joint
classification effort (nearshore and offshore)
• Habitat heterogeneity greatest at boundary between
Coastal Margin and Nearshore/ Open-Water Zone
• Scale and Resolution Issues
• Physical, Biological, and Chemical attributes
Lake Erie Binational Map Project
Habitat
Habitat
Habitat
Habitat
Habitat
Habitat
Habitat
Habitat
Habitat
Habitat
Habitat
Habitat
Nearshore Coastal Margins
• Nearshore habitats are critical and essential to the
Great Lakes ecosystem.
• Anthropogenic impacts alter substrate characteristics,
water depth, water quality, and energy dynamics of
the nearshore zone.
• Anthropogenic impacts have both a direct and an
indirect impact on the Lake Erie ecosystem.
Nearshore Coastal Margins
• Problem:
– Nearshore biological processes and biological
linkages to nearshore structural habitats are not
well-studied and poorly understood.
• Significance:
– Regulatory decisions affecting the nearshore zone
are made without adequate scientific data.
– What elements of the Lake Erie ecosystem are
nearshore and coastal habitat limited?
Coastal Margin (Nearshore)
• Identify and map bottom substrates
– Sonar : Sidescan and Swath (acoustic backscatter)
– Sampling
• Document changes in substrate distribution
–
–
–
Area (m2)
Centroids (centers of mass)
Change patterns (magnitude and direction, distribution)
• Evaluate environmental characteristics
– Substrate classification (infer composition, grain size)
– Substrate stability