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

The mean (± S.E.) total number of infauna is shown for the three reef types in Figure 2.  These values were compared across the three collection periods: pre-restore, one-month post-restoration, and six months post-restoration.  Infaunal abundance increased on restored oyster reefs following restoration; from pre-restore to one-month post-restoration, restored reefs show an average increase in infauna of 231 organisms (Figure 2).  A two-way ANOVA with interaction (Reef Type x Time) tested the significance of these results.  The interaction between reef type and time was found to be significant [F (8, 96) = 9.83, p < 0.0001], demonstrating that both reef type and collection time impacted abundance.  Before restoration, dead reefs had an average of 520 fewer organisms than live reefs and restored reefs had an average of 450 less organisms than live reefs.  Furthermore, before restoration dead and restored reefs had an average difference in abundance of only 70 organisms, indicating that before restoration, restored and dead reefs had similar infaunal abundance, while live reefs had a much higher abundance.

Figure 2 shows additional, preliminary patterns suggesting that infaunal abundance on restored reefs does increase following restoration and therefore suggests that restored reefs become more similar to live reefs over time.  By one month after restoration, restored reefs increased in infaunal abundance by about 230 organisms, which was a 90% increase in infauna.  One-month restored reefs had an average of 290 fewer organisms than live reefs at the one-month collection time.  By six months post-restoration, restored reefs had only an average of 31 less organisms than live reefs.  The difference in abundance between dead and restored reefs became greater over time.  At one month after restoration, restored reefs had an average of 228 more organisms than dead reefs, and by six months restored reefs had an average of 358 more organisms than dead reefs.  Restored reefs were most similar to live reefs at six months after restoration, but this result may be associated with a seasonal temporal decline in infaunal abundances across all reef types at this colder January collection time.  The results of these comparisons support the hypothesis that following restoration, infaunal abundance on restored reefs increased and started to become more similar to infaunal abundance on live reefs.

Polychaetes were the most abundant type of infaunal organism found on all reefs (Figure 3).  Polychaetes consisted of many species within this taxon.  Some of the common polychaetes identified to the family level included Nereididae, Opheliidae, Hesionidae, Syllidae, and Spionidae (Table 1).  These infaunal polychaetes were typically less than two centimeters in length.  Polychaetes in the family Eunicidae were much larger at five to eight centimeters in length.  Eunicidae was not very abundant on oyster reefs, with typically only three to five of this taxa found in a sample.  However, these polychaetes were larger than the other infaunal organisms and thus worth noting.  Eunicidae were found on live oysters reefs and on some restored reefs following restoration.

There was an average increase in amphipod abundance by about 100 organisms on restored reefs one month after restoration and slight increases in isopod, bivalve, and decapod abundances (Figure 4).  Gammaridae and Ampithoidae were common infaunal amphipod families identified on oyster reefs (Table 1).  A few Corophiidae and Caprellidae amphipods were also identified.  The most common isopod species found were Harrieta faxoni (family: Sphaeromatidae) and Amakusanthura magnifica (family: Anthuridae).   There were a few different species of bivalves, but bivalves mainly consisted of species in the Tellinidae family.  The main gastropod species found were mostly likely of the Vitrinellidae family.  Only two species of decapods were found and identified – the porcelain crab Petrolisthes armatus (family: Porcellanidae) and the Atlantic mud crab Panopeus herbstii (family: Panopeidae).  Both crabs were most common on live reefs and restored reefs following restoration.  

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