University of Central Florida Undergraduate Research Journal - Oyster Reef Restoration: Impacts on Infaunal Communities in a Shallow Water Estuary
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Methods

Infaunal organisms were collected from 12 intertidal oyster reefs in Mosquito Lagoon: four dead, four live, and four restored reefs, spanning a distance of about three km (Figure 1).  All 12 sites were part of a large, multi-investigator study of the effects of restoration on infauna, sessile invertebrates, mobile invertebrates, fishes, and wading birds in Mosquito Lagoon.  Infaunal samples were collected one week pre-restoration (June 2017), and one month (July 2017) and six months (January 2018) post-restoration. Three samples were collected per site from the mid-intertidal reef level on each sampling date.  The mid-intertidal reef level was chosen as the sampling area because it is expected that many infaunal predators use this part of the reef throughout the tidal cycle.  A quadrat was used to maintain an area of 15 cm x 15 cm on the surface of the reef.  Sediment was collected to 15 cm deep, obtaining a sediment volume of 15 cm x 15 cm x 15 cm.  The samples were pre-sieved using a bucket with mesh (2 cm diameter) in place of the bottom.  This mesh removed all larger shell material from each sample.  The remaining sediment was then sieved through a 2000-micron sieve and a 500-micron sieve.  All sediment and organisms retained in the 500-micron sieves were kept.  Any larger infaunal organisms found in the 2000-micron sieve were also kept.  The samples were stored in containers with 200 mL of seawater; 50 mL of a formaldehyde (preservative) and a rose bengal (vital stain) mixture was added to the seawater to obtain a seawater to formaldehyde ratio of 4:1. After one week, the samples were sieved a second time through the 500-micron sieve to reduce the amount of sediment retained.  The samples were then transferred to 75% ethanol for long-term storage.

Infaunal organisms, already preserved in ethanol, were sorted from the sediment samples using a dissecting microscope (magnification: 20X).  Organisms were counted to assess infaunal abundance per sample and sorted into one of the six taxonomic categories: polychaete, amphipod, isopod, bivalve, gastropod, or decapod.  Infaunal organisms that did not fit into one of these categories were rare and were not included in the subsequent analyses.  Sorted infaunal organisms were stored in glass scintillation vials with 75% ethanol.

A two-way ANOVA with interaction (Reef Type x Time) was used to compare the reef type and time for the total abundance of infauna. Data did not violate the assumptions of the ANOVA.  This test was run in the statistical program R with a significance level of p = 0.05. 

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