Jocelyn Karazsia; Kevin Mack; Pace Wilber; Margaret Miller; Sean Griffin; Tom Moore

Examination of Sedimentation Impacts to Coral Reef along the Port Miami Entrance Channel, December 2015 and April 2016

2023

NOAA's National Marine Fisheries Service (NMFS)

"In December 2015 and April 2016, NOAAs National Marine Fisheries Service (NMFS) assessed potential damage from dredged sediments to coral reefs adjacent to the Port Miami Entrance Channel. This was an unprecedented evaluation based on concerns brought to us by various partner, regulatory, and action agencies and after reviewing satellite images depicting large sediment plumes over areas of coral reef. The work conducted during December 2015 examined the Inner Reef North of the channel, and the work completed during April 2016 included the Inner Reef south of the channel. The purpose of the surveys was to further our understanding of the spatial extent and severity of sediment-related impacts resulting from the dredging. Our surveys were limited to areas mapped as reef or hardbottom before the dredging began and focused on determining bottom cover, measuring sediment depth, and recording coral condition related to sediment stress after dredging ceased. We found bottom cover at sediment assessment locations differed significantly from reference locations. The bottom cover class sediment over hardbottom was the primary driver of the variation along the Inner Reef, representing an average of 42% of bottom cover observations at sediment assessment locations, compared to only 7% at reference locations. The mean sediment depth also differed significantly between Inner Reef sediment assessment locations and reference locations. On the Inner Reef, severe impacts to coral reef habitat from sediments occurred over an estimated 278 acres of reef, and lesser impacts likely extended to an even larger area. We view this acreage estimate as conservative for many reasons, including, but not limited to, exclusion from the acreage calculation of the nearby patch reefs, artificial reefs, Outer Reef, and Nearshore Ridge Complex. NMFS will use this information to help Port Miami, state and federal agencies, and other stakeholders with planning the Port Miami Phase IV dredging. This report helps establish the environmental baseline by enumerating the acres of coral reef affected by the unplanned sedimentation impacts. The report also will guide subsequent surveys needed by the USACE and Port Miami to determine the mitigation needed for Port Miami Phase III and Phase IV."

coral, coral reef, sedimentation, dredging, impact assessment, Port Miami, Florida

NMFS

SERO

FY2023 CRCP Project ID 30049; Project Title: NMFS Contract Positions to Suport Fisheries Local Action Strategies in Florida, Puerto Rico, and the USVI ; Principal Investigator: Joceyln Karazsia