Deep reef fish surveys by submersible on Alderdice, McGrail, and Sonnier Banks in the Northwestern Gulf of Mexico

Submersible surveys at numerous reefs and banks in the northwestern Gulf of Mexico (NWGOM) were conducted as part of the Sustainable Seas Expedition (SSE) during July/August 2002 to identify reef fish communities, characterize benthic habitats, and identify deep coral reef ecosystems. To identify the spatial extent of hard bottom reef communities, the Flower Garden Banks National Marine Sanctuary (FGBNMS) and the U.S. Geological Survey (USGS) mapped approximately 2000 km2 of the Northwestern Gulf of Mexico (NWGOM) continental shelf during June 2002 with high-resolution multibeam bathymetry. Previous investigations conducted on the features of interest (with the exceptions of East and West Flower Garden and Sonnier Banks, accessible by SCUBA) had not been conducted since the 1970s and 1980s, and did not have the use of high-resolution maps to target survey sites. The base maps were instrumental in navigating submersibles to specific features at each study site during the Sustainable Seas Expedition (SSE)—a submersible effort culminating from a partnership between the National Atmospheric and Oceanic Administration (NOAA) and the National Geographic Society (NGS). We report the initial findings of our submersible surveys, including habitat and reef fish diversity at McGrail, Alderdice, and Sonnier Banks. A total of 120 species and 40,724 individuals were identified from video surveys at the three banks. Planktivorous fishes constituted over 87% by number for the three banks, ranging from 81.4% at Sonnier Banks to 94.3% at Alderdice Bank, indicating a direct link to pelagic prey communities, particularly in the deep reef zones. High numbers of groupers, snappers, jacks, and other fishery species were observed on all three features. These sites were nominated as Habitat Areas of Particular Concern (HAPC) by the Gulf of Mexico Fishery Council in March 2004. Data obtained during this project will contribute to benthic habitat characterization and assessment of the associated fish communities through future SCUBA, ROV, and submersible missions, and allow comparisons to other deep reef ecosystems found throughout the Gulf of Mexico and western Atlantic Ocean

Introduction: Flower Garden Banks National Marine Sanctuary

Moving into the second decade as a National Marine Sanctuary—exploration, research, and protection continues to evolve through advancements in technology and a sense of adventure. A program of targeted research prepares this Sanctuary to address critical management priorities and to adapt management programs as new issues arise. Recent research demonstrates that the reefs of the Flower Garden Banks are not isolated islands of diversity but are an integral part of a network of interconnected biological features of the northwestern Gulf of Mexico

Flower Garden Banks National Marine Sanctuary: Introduction

The history of exploration, research, and environmental protection at the Flower Gardens is a model of accomplishment through partnerships—a demonstration of how a spirit of mutual support leads to the achievement of shared goals

Black Corals of the Flower Garden Banks National Marine Sanctuary

Black corals (Cnidaria: Anthozoa: Antipatharia) of the Flower Garden Banks National Marine Sanctuary (FGBNMS) are described. A key to the species is provided and supplemented with in situ and laboratory photos. The microscopic skeletal features of the species are illustrated from photographs taken with a scanning electron microscope. Thirteen species of black corals are found in the FGBNMS, belonging to the families Antipathidae (Antipathes furcata Gray 1857; Antipathes atlantica Gray 1857, Stichopathes luetkeni Brook 1889; Stichopathes pourtalesi Brook 1889, and Stichopathes sp.); Aphanipathidae [Aphanipathes pedata (Gray 1857), Elatopathes abietina (Pourtalès 1874), Acanthopathes thyoides (Pourtalès 1880) and Phanopathes expansa (Opresko and Cairns 1992)]; and Myriopathidae [Plumapathes pennacea (Pallas 1766), Tanacetipathes tanacetum (Pourtalès 1880), Tanacetipathes hirta (Gray 1857), and Tanacetipathes cf. thamnea (Warner 1981)]

Validation of Image-Based Species Identifications of Black Corals (Order Antipatharia) on Mesophotic Rocks

Biodiversity, an important measure of ecosystem health, is challenging to ascertain using sampled specimens in remote deep-sea environments. As image-based identifications become a predominant method for deep-sea species characterizations, there is a need to evaluate the accuracy of species- and genus-level identifications from video and still images to provide a reliable measure of biodiversity. This study presents a validation of the ability to make accurate image-based identifications of black coral species in the northwestern Gulf of Mexico from standard-definition video collected by a remotely operated vehicle. Results indicate that the greatest number of misidentifications occurred at species-level groupings (42.2% error), whereas genus-level groupings possessed 12.0% error, and identifications to kappa groupings had no error. We recommend genus-level groupings to maintain accurate identifications while maximizing estimates of biodiversity

Patterns of Mesophotic Benthic Community Structure on Banks Off vs Inside the Continental Shelf Edge, Gulf of Mexico

Information on the biodiversity and geographic patterns of mesophotic, sessile, epibenthic communities on banks around and at the edge of the continental shelf, northern Gulf of Mexico, has been limited. These communities vary in their environments and are prone to disturbance from Outer Continental Shelf oil- and gas-related activities and fishing (trawling and long-lining). We surveyed these communities on the flanks of 13 banks to determine species richness, species composition, similarities between benthic communities, and geographic patterns in community structure. We sampled to ≤ 181 m in depth via a remotely operated vehicle using a vertically mounted digital camera bearing two lasers for scale and a flash (generally 10 drop-sites/bank, 5 transects/drop-site, and ≤11 photos/transect). Data analysis via PATN revealed three main Bank Groups: the on-shelf group containing 29 Fathom and Sonnier Banks; an anomalous bank—Geyer Bank; and the shelf edge group—Horseshoe, 28 Fathom, Bright, Alderdice, Bouma, Rankin, Rezak, Elvers, McGrail, and Sidner Banks. Most species-rich banks (Bank Group 3) occurred at the shelf edge. Two of the species-poor banks (Bank Group 1) occurred further north, inside the shelf. Geyer Bank (Bank Group 2) occurred at the shelf edge but was anomalously species-poor. Box-and-whisker analyses identified four Species Groups driving the Bank Groupings. Species Group 4 (the Elatopathes abientina/Nicella sp. group) was the largest (also containing Peysonellia sp.), primarily defining Bank Group 3. Species Groups 2 (the Antipathes sp./Gorgonian G04 group) and 3 (low species abundances) were also associated with Bank Group 3. Species Group 4 (the Elatopathes abientina/Nicella sp. group) was a major contributor to Bank Group 2 (Geyer Bank). Species Group 2 (the Antipathes sp./Gorgonian G04 group) was the primary constituent of the on-shelf Bank Group 1, also characterized by low species richness. Most species had a comparative abundance of ≤20%. The high species richness and affinities exhibited by Bank Group 3 are likely due to continual exposure to warm, low-turbidity Caribbean water at the shelf edge. Banks inside the shelf likely vary from the others as a result of exposure to cooler winter temperatures and higher turbidity due to wind-forced inshore currents. The reasons for the unique community structure on Geyer Bank are as yet unknown. Shelf-edge banks tend to be more species rich than on-shelf banks

Patterns of Mesophotic Benthic Community Structure on Banks Off vs Inside the Continental Shelf Edge, Gulf of Mexico

Information on the biodiversity and geographic patterns of mesophotic, sessile, epibenthic communities on banks around and at the edge of the continental shelf, northern Gulf of Mexico, has been limited. These communities vary in their environments and are prone to disturbance from Outer Continental Shelf oil- and gas-related activities and fishing (trawling and long-lining). We surveyed these communities on the flanks of 13 banks to determine species richness, species composition, similarities between benthic communities, and geographic patterns in community structure. We sampled to ≤ 181 m in depth via a remotely operated vehicle using a vertically mounted digital camera bearing two lasers for scale and a flash (generally 10 drop-sites/bank, 5 transects/drop-site, and ≤11 photos/transect). Data analysis via PATN revealed three main Bank Groups: the on-shelf group containing 29 Fathom and Sonnier Banks; an anomalous bank—Geyer Bank; and the shelf edge group—Horseshoe, 28 Fathom, Bright, Alderdice, Bouma, Rankin, Rezak, Elvers, McGrail, and Sidner Banks. Most species-rich banks (Bank Group 3) occurred at the shelf edge. Two of the species-poor banks (Bank Group 1) occurred further north, inside the shelf. Geyer Bank (Bank Group 2) occurred at the shelf edge but was anomalously species-poor. Box-and-whisker analyses identified four Species Groups driving the Bank Groupings. Species Group 4 (the Elatopathes abientina/Nicella sp. group) was the largest (also containing Peysonellia sp.), primarily defining Bank Group 3. Species Groups 2 (the Antipathes sp./Gorgonian G04 group) and 3 (low species abundances) were also associated with Bank Group 3. Species Group 4 (the Elatopathes abientina/Nicella sp. group) was a major contributor to Bank Group 2 (Geyer Bank). Species Group 2 (the Antipathes sp./Gorgonian G04 group) was the primary constituent of the on-shelf Bank Group 1, also characterized by low species richness. Most species had a comparative abundance of ≤20%. The high species richness and affinities exhibited by Bank Group 3 are likely due to continual exposure to warm, low-turbidity Caribbean water at the shelf edge. Banks inside the shelf likely vary from the others as a result of exposure to cooler winter temperatures and higher turbidity due to wind-forced inshore currents. The reasons for the unique community structure on Geyer Bank are as yet unknown. Shelf-edge banks tend to be more species rich than on-shelf banks

An annotated and illustrated identification guide to common mesophotic reef sponges (Porifera, Demospongiae, Hexactinellida, and Homoscleromorpha) inhabiting Flower Garden Banks National Marine Sanctuary and vicinities

Sponges are recognized as a diverse and abundant component of mesophotic and deep-sea ecosystems worldwide. In Flower Garden Banks National Marine Sanctuary region within the northwestern Gulf of Mexico, sponges thrive among diverse biological and geological habitats between 16–200+ m deep (i.e., coral reefs and communities, algal nodules, and coralline algae reefs, mesophotic reefs, patch reefs, scarps, ridges, soft substrate, and rocky outcrops). A synoptic guide is presented, developed by studying common sponge species in the region, through direct sampling and in-situ photographic records. A total of 64 species is included: 60 are Demospongiae (14 orders), two are Hexactinellida (one order), and two are Homoscleromorpha (one order). Thirty-four taxa are identified to species and 13 were identified to have affinity with, but were not identical to, a known species. Fifteen taxa could only be identified to genus level, and the species remain as uncertain (incerta sedis), with the potential to represent new species or variants of known species. One specimen received only a family assignation. This study extends geographic or mesophotic occurrence data for eleven known species and includes several potentially new species. This work improves our knowledge of Gulf of Mexico sponge biodiversity and highlights the importance of the region for scientists and resource managers

Stetson Bank long-term monitoring: 2020 and 2021 annual report

This document contains descriptions of the methods used, analyses of field data collected, summaries of field notes, details of challenges faced, and significant observations made during 2020–2021 annual long-term monitoring of fish and benthic communities at Stetson Bank. Stetson Bank is an uplifted claystone/siltstone feature located 130 km southeast of Galveston, Texas within Flower Garden Banks National Marine Sanctuary in the northwestern Gulf of Mexico. It supports a productive benthic community of sponges and coral. Annual monitoring of the bank crest has been conducted since 1993. Surveys of the mesophotic zone surrounding the bank crest began in 2015. Field work and data collection were limited in 2020 and 2021 due to vessel, diving, and operational restrictions established in response to the COVID-19 pandemic. In 2020, a single quarterly water sampling cruise was completed, followed by a cruise for water quality instrument exchange. In 2021, two water sampling cruises were completed, and instruments that recorded temperature, salinity, and turbidity data since 2019 were exchanged. A subset of bank crest repetitive photostations (n = 24), representing 40% of all photostations on the Stetson Bank crest, were captured in 2021. In 2021, mean percent cover was 6.56% for coral, 7.09% for sponges, and 42.72% for macroalgae. Bleaching and/or paling was observed in Millepora alcicornis colonies in 2021; however, no signs of stony coral tissue loss disease were observed. Seawater temperatures on the bank exceeded 30 oC for one day in 2020 and for 18 nonconsecutive days in 2021. This report highlights the importance of long-term monitoring efforts by providing a summary of benthic and water quality trends on the bank crest and detailing challenges and resolutions for future field work.This study was funded by the U.S. Department of the Interior, BSEE through Interagency Agreement E21PG00009 with NOAA’s National Ocean Service, ONMS, through FGBNMS. Field work in 2020 and 2021 was carried out under permit FGBNMS-2019-001