Pascagoula, MS Pascagoula River estuary, SE Mississippi The pascagoula is a river dominated estuary on the SE coast of Mississippi possessing both heavily altered shoreline and large stretches of natural marsh, making it an ideal location for this particular study Pascagoula River estuary, SE Mississippi Possesses both heavily developed shoreline & long stretches of natural marsh Gradient of development makes this an ideal study location

Methods: Impact zone/Shore type Impact zone: presence/ extent of shoreline alteration in a defined area Shoreline graphically generated, types delineated Restricted, hardened, leveed, beach Unrestricted, marsh edge > 2m wide Habitat patchiness quantified In this study, I use the term Impact zone to describe the presence and extent of shoreline alteration within a given area. Impact zones were chosen to encompass 3 areas of equal size along the eastern distrib of the lower Pascagoula along the gradient of disturbance. Using QuickBird satellite imagery I generated shape files of the shoreline in each Impact zone and gave it the distinction of ‘restricted’ or unrestricted. Total shorelength was calculated for each Impact zone, as well as the ratio of restricted to unrestricted shore type. With this information I was able to calculate habitat patchiness, or the amount of disconnect between like habitat patches.

Drop sampling Habitat characteristics Assemblage analysis Sediment TOC Water quality Assemblage analysis Benthic Infauna Epifauna/nekton Sample sites were randomly chosen within each sample, such that samples were taken at two restricted and two unrestricted shore sites within each Impact zone, yielding 12 samples total. Drop sampling was performed using the methods described in Zimmerman et al. 1984. At each drop sample, 3 cores were taken from within the sampler for sediment grain size analysis, total organic carbon content, and benthic infauna diversity/density. Habitat characteristics including salinity, temp, do, ph, chlor, turb, live/dead stem count and water depth were also take from within the drop sampler prior to water removal. The contents of the sampler were removed using a 5.5 hp honda pump, water was drawn out of the sampler and passed through a .5mm mesh net. Once water had been removed, fine-mesh dip nets were used to remove any remaining animals, until 5 consecutive empty sweeps.

Results: Impact zone/Shore type Impact zones 3.34 km2 Grid size 1.17 km2 Twelve sample sites IZ1 – severe alteration, mouth of river IZ2 – moderate alteration, mid-point IZ3 – near pristine conditions, 5 km upstream Three Impact zones, 3.34 km2. Grids used to randomly choose sampling sites. Sample sites in yellow (n=12). Impact zone 1, at the river’s mouth is the most severely altered of the Impact zones. Impact zone 2 is an intermediate in both spatial relationship and degree of alteration. Impact zone three is the most natural Impact zone with a minimum of impact. It’s 5km up stream from the river mouth. Partyka & Peterson 2009

PCA 3-D plots of pc2v3 with epifauna/nekton richness (left) and infauna richness (right) as a third axis. Red circles used to illustrate the close grouping of all restricted samples mid-way on the PC2 axis and on the negative end of PC3. Note richness for both epifauna/nekton and infauna is consistenly higher in unrestricted samples

Conclusions Connectivity between marsh habitat and complexity of shore line greatest in IZ 3 (near pristine) Dominance of polychaetes and nematodes in IZ 1 (high impact) may reflect high disturbance or presence of other stressors Vegetated habitats had consistently greater richness & density of both infauna & epifauna/nekton Much more to be learned and understood regarding the relationships between shoreline alteration & species assemblages In this study, connectivity greatest between marsh habitat in IZ3. Interspersion of restricted and unrestricted may explain the increased used of the less desirable restricted habitat in IZ2. Dominance of polychaetes and nematodes in Impact zone 1 may be indicator of disturbance or other stressors. Though the presence of vegetation wasn’t enough to guarantee high diversity and high density, these values were always higher, if only marginally, in the presence of vegetation.