Title

Calypso LNG Deepwater Port Project, Florida: Marine Benthic Video Survey

Document Type

Article

Publication Date

6-12-2006

Abstract

  • The benthic video survey carried out for the Calypso Liquefied Natural Gas Deep Water Port Project (LNG DWP) examined ~52 nm of linear transects of the seafloor off Fort Lauderdale, FL, in and to the north of the geohazards survey area using the US Navy’s Television Observed Nautical Grappling System (TONGS) remotely operated vehicle (ROV) conducted from 15 to 18 April 2006.
  • Analyses of videographic and still photographic data revealed six habitat types: 1) Sediment (obsolete rippled and flat bioturbated), 2) Large-scale sediment features – large depressions and sand waves. 3) Tilefish burrows – one great northern tilefish (Lopholatilus chamaeleonticeps), and a few burrows of probable blueline tilefish (Caulolatilus microps). 4) Pennatulids – chiefly widely scattered colonies of a sea pen in >900 ft. 2) Low-cover hard bottom – scattered clusters of rubble or small rocks, often in patches a few meters across, rarely in more extensive fields, and separated by expanses of sediment, occasionally accompanied by a few low-relief rocks up to 0.8 m across and rare veneered slabs or pavements to 1 m across. 3) High-cover hard bottom – low- to moderate-relief characterized by phosphoritic limestone outcrops, pavement and slabs, each chieflyacross, with varying amounts of rubble and small to large rocks, frequently in patches separated by expanses of sediment and intermixed with low-cover hard-bottom areas.
  • The most abundant organisms on hard bottoms were a variety of sea anemones (Actiniaria), nephtheid soft corals (?Capnella nigra), zoanthids (colonial anemones) and echiuran spoon worms, accompanied by smaller numbers of primnoid and isidid octocorals, stylasterid lace corals, demosponges and hexactinellid glass sponges. The only stony corals observed were small solitary azooxanthellate cup corals (=2 cm) (except for two small branching colonies on the fuselage of a sunken airplane).The most common fish in this habitat was the blacktail codling, Laemonema melanurum (Moridae). Four large fishes (grouper or snapper) were seen in side cameras.
  • A total of 869 still images were analyzed in eight still photographic series identified as having high biological interest (based on organism abundance and diversity, and extent of exposed hard substrate), ranging from 82 to 136 per series with a mean of 108.6 images per series. Coral Point Count (CPC)© software was used to code 50 points in each image. Hard substrates accounted for 17.10 to 95.32% of cover in these eight selected predominantly hard bottom areas. Percent coverage by all organisms combined (mobile and sessile) ranged from 1.01 to 9.00%.
  • We also counted all organisms larger than 3-4 cm in the same image set. Area covered ranged from 52.12 to 182.04 m2 per site. Total organism densities ranged from 3.85 to 10.80 m-2, with sessile and semi-sessile habitat-forming groups (sponges and cnidarians) ranging from 3.15 to 6.49 m-2. Sea anemones were the most abundant organisms at 5 of 8 sites, with zoanthids and echiurans most abundant in the other three. Capnella nigra ranked second through fourth. Maximum densities of dominant groups were echiurans (3.32 m-2), zoanthids (2.86 m-2), sea anemones (1.90 m-2), nephtheids (1.22 m-2), and total sponges (0.71 m-2). No other group occurred at densities greater than 0.5 m-2. Organisms treated as corals contributed at most 0.48 (gorgonians) and 0.45 colonies m-2 (stylasterids), both at site 8.

Report Number

Final Report

Comments

Submitted to: Ecology and Environment, Inc. & SUEZ Energy North America, Inc.

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