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

Shallow water use project objectives 1.Assess tidal creek fish community characteristics in Lynnhaven Bay 2.Compare fish communities in dredged and undredged tidal creek systems 3. Inventory shoreline condition in Lynnhaven Bay -- including land use, structures and bank conditions

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

Fish Survey Locations: August-October 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

Push Nets Beach Seines Experimental Gill nets Water Quality measures Multiple facets of the fish communities were targeted with different gear types For example: nearshore juvenile species—beach seine

0.05 km km 2 Dredged Feb 2006

0.6 km km 2 Dredged Mar 2000

0.6 km km 2 Dredged Jul 2000

Site Characteristics on Average: August-October 2006

Extreme variability in basic water quality measures: e.g. Salinity, Temperature, Dissolved Oxygen, Turbidity Ernesto

Fish Survey Results 5972 fish and 31 species collected 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 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 2.3—50 cm) Blackcheek tonguefish Bluefish Permit Sheepshead minnow Crevalle jack Hogchoker Ladyfish Sharptail goby Spotted seatrout Tripletail Weakfish

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).

CreekD/U Size (km 2) Abu No. Spp = 99% NorthU NorthD HebdenU HebdenD BuchananU BuchananD General Community Characteristics among Creeks

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

Fish Community Characteristics among Creeks Variety of ways to describe communities: 1)Abundance 2)Biomass 3)Size 4)Diversity 5)Fish community index

No Significant difference among sites surveyed (grouped by month) for Abundance or Biomass

SIZE—NO difference among creeks or across months!! Beach Seine Gill Net All Data

Diversity Among Creeks: NO significant difference!! One-way ANOVA

Metrics were combined into an aggregate index--Fish Community index (FCI)- - used to assess relative measures of fish community structure and function. Fish Community Metrics Species Richness/Diversity Measures Species Richness Proportion of benthic-associated species Number of dominant species (90% of total abundance) Number of resident species Fish Abundance Ln Abundance Trophic Composition Trophic Index Nursery Function Number of estuarine spawning species Number of estuarine nursery species Fish Community Index (FCI)

Fish Community Index comparison among creeks NO difference!

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.

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. Shoreline Continuous Inventory: Lynnhaven Bay

Dix Creek Example survey map of Shoreline structures in Lynnhaven Bay Preliminary Results: Total Survey Miles: Coded Miles: Marsh Islands Miles: ~ Line structures for the coded shl: miles So far we estimate ~30% of coded shoreline is hardened TMI (from 1970s): acres

Webpage for Shoreline Inventory Data, Maps and Reports haven/lynnhaven_disclaimer.html