MS Thesis Defense: Maxwell Tice-Lewis

The Department of Marine Sciences and The Institute of Marine Sciences (IMS) is proud to present the M.S. Thesis Defense of Maxwell Tice-Lewis. The main location of this event will be in room 222 at IMS in Morehead City, NC. The defense will be simultaneously streamed live to seminar room G201 on the ground floor of Murray Hall on UNC campus in Chapel Hill, NC. This event will be held on Monday, May 14th at 12:20 PM.

Title: Spatiotemporal patterns in biogenic-reef associated faunal communities over interannual and multidecadal timescales

Abstract: Understanding how biogenic-habitat associated species assemblages vary over space and time is necessary for making effective habitat restoration choices and predicting future ecological outcomes under global climate change. Biogenic habitats such as oyster-reefs, seagrasses, and salt marshes offer important structured habitat for a high diversity of fauna, are characteristic features over coastal estuarine landscapes, and occur over abiotic gradients in aerial exposure and salinity. To better understand how biogenic-habitat associated faunal assemblages vary over gradients in salinity and aerial exposure, we surveyed 11 oyster-reefs in two adjacent temperate estuaries in NC, spanning polyhaline-euryhaline salinity gradients and including intertidal and subtidal sites. We gathered historical salinity records to establish whether known changes in relative sea level and dredging practices over the last six decades may have influenced salinity dynamics in the Newport River estuary (NPRE). We also re-visited (2013-2015) sites sampled by Harry Wells (1955-1956) to determine long-term changes in oyster-reef distribution and their associated fauna. Oyster density was positively correlated with aerial exposure, but intertidal reef diversity was less influenced by salinity than on subtidal reefs. Community structure varied according salinity across aerial exposures, but was more variable on subtidal reefs. Over multi-decadal timescales, salinity means and extrema increased at upper estuary sites, and salinity lows increased at lower estuary sites. Oyster-reef faunal assemblages differed between analogous sites over time and community turnover between sites along the salinity gradient grew more similar over time, indicating a reduction in community turnover correlating with salinity increases. We propose a form of coastal narrowing has taken place in the NPRE, where oyster-reef community diversity is more homogeneous and available abiotic conditions for subtidal oyster-reef survival are shrinking. Continued increases in rSLR may continue this narrowing process through saltwater intrusion, further constricting oyster reef habitat and associated community diversity.