Project Update

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Project Update Shallow Water Use Studies
and Shoreline Inventory Donna Marie Bilkovic
and Marcia Berman Center for Coastal Resources
Management Virginia Institute of Marine
Science June 2007
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• Shallow water use project objectives
• Assess tidal creek fish community characteristics
  in Lynnhaven Bay
• Compare fish communities in dredged and
• undredged tidal creek systems
• 3. Inventory shoreline condition in Lynnhaven Bay
  --
• including land use, structures and bank conditions

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• Coastal development stressors on estuarine
  communities include
• Shoreline hardening
• Land use conversion
• Vegetation removal
• Dredging
• Possible stressors caused from dredging with
  particular importance to fish
• Habitat removal
• Loss of prey items (e.g. burial of benthos)
• Increased turbidity
• Alteration of physical habitat (e.g. sediment,
  current patterns, water quality, salinity,
  reduction in flushing)
• What are the recovery rates of fish communities?
• Research on benthic communities indicates
  recovery rates are dependent on several factors
  including salinity, system size, and sediment
  grain size. (faster in fine-grained and lower
  salinity regions)
• Limited research on fish recovery rates in tidal
  creek systems

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Fish Survey Locations August-October 2006 6
Creeks in the Western Branch (3 dredged 3
undredged)
Each Creek sampled with multiple gear types
Monthly
When Dredged North Creek Feb
2006 Hebden Creek Mar 2000 Buchanan Creek
Jul 2000
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Multiple facets of the fish communities were
targeted with different gear types For example
nearshore juvenile speciesbeach seine
Water Quality measures
Experimental Gill nets
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0.05 km2
0.09 km2
Dredged Feb 2006
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Dredged Mar 2000
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Dredged Jul 2000
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Site Characteristics on Average August-October
2006
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Extreme variability in basic water quality
measures e.g. Salinity, Temperature, Dissolved
Oxygen, Turbidity
Ernesto
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• Fish Survey Results
• 5972 fish and
• 31 species collected

The catches in the systems combined were
dominated by Atl silverside, Bay anchovy, Gizzard
shad, Silver perch, and Atl. menhaden Average
sizes 13.9 4.6 cm (range 2.350 cm)

• Other Spp
• Blue Crab
• Mummichog
• Spot
• Red Drum
• Mullet spp
• Atl. Croaker
• White Perch
• Killifish spp
• Spotfin mojarra
• American eel
• Striped bass
• Summer flounder
• Naked goby

Blackcheek tonguefish Bluefish Permit Sheepshead
minnow Crevalle jack Hogchoker Ladyfish Sharptail
goby Spotted seatrout Tripletail Weakfish
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The majority (72) of the blue crabs captured
were juveniles and many were extremely small
indicating that the Lynnhaven is used as a
nursery ground. 26 adults were captured (11
female and 15 male).
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General Community Characteristics among Creeks
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Species overlays 1) Spot more prominent in the
upriver systems Hebden and Buchanan 2) Red drum
in higher abundance in undredged systems vs.
dredged systems
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• Fish Community Characteristics among Creeks
• Variety of ways to describe communities
• Abundance
• Biomass
• Size
• Diversity
• Fish community index

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No Significant difference among sites surveyed
(grouped by month) for Abundance or Biomass
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SIZENO difference among creeks or across months!!
Beach Seine
All Data
Gill Net
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Diversity Among Creeks NO significant
difference!!
One-way ANOVA
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Fish Community Index (FCI)
Metrics were combined into an aggregate
index--Fish Community index (FCI)-- used to
assess relative measures of fish community
structure and function.
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Fish Community Index comparison among creeks
NO difference!
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• Preliminary Conclusions
• All six creeks supported similar fish communities
• Slight differences among fish communities (seen
  in multivariate analyses) may be related to the
  size of the watershed (i.e. North creeks
  differed)
• Extreme variability in physical and chemical
  features in the Lynnhaven are driving influences
  to structuring fish communities
• Diverse communities in Lynnhaven (related to its
  location at the Bay mouth) utilize the Bay as
  feeding/nursery grounds
• The most recently dredged system was similar to
  the adjacent undredged system (North creeks)
  which may indicate a quick recovery rate for fish
  communities post-dredging
• HOWEVER, presence of fish does not mean no impact
  occurs from dredging, information on prey
  communities is necessary, as well as long term
  studies to estimate impacts.

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Shoreline Continuous Inventory Lynnhaven Bay
Three-tiered shoreline assessment approach,
dividing the shorezone into three regions
1) the immediate riparian
zone, evaluated for land use 2) the
bank, evaluated for height, stability, cover and
natural protection and 3) the
shoreline, describing the presence of shoreline
structures for shore protection and recreational
purposes.
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Example survey map of Shoreline structures in
Lynnhaven Bay
Preliminary Results Total Survey Miles  139.42
Coded Miles  107.46 Marsh Islands Miles
17.69 Line structures for the coded shl
 26.12 miles So far we estimate 30 of coded
shoreline is hardened TMI (from 1970s) 1157.1
acres
Dix Creek
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Webpage for Shoreline Inventory Data, Maps and
Reports http//ccrm.vims.edu/shoreline_inventori
es/virginia/lynnhaven/lynnhaven_disclaimer.html