Florida Keys National Marine Sanctuary Research Articles

Coral reefs and climate change: Examining two institutional approaches to managing a novel marine ecosystem

Much of Florida’s economy is tied to the third-largest barrier reef in the world, the Florida Reef Tract. However, because of anthropogenic threats, it is not the thriving ecosystem it once was, and its persistence requires new, unconventional management strategies. Two entities have emerged to address this problem: the Florida Keys National Marine Sanctuary, a formally structured regulatory authority, and the Southeast Florida Coral Reef Initiative, an informal network of stakeholder partnerships. We therefore ask: How does coral reef management vary over the different spatial extents and structures of these organizations, and how do these organizations vary in incorporating important aspects of novel ecosystem management? Using 1122 statements from news documents, public meeting transcripts, and stakeholder interviews, we compare the institutional elements of each organization and determine the importance they place on five management considerations. Our results indicate significant institutional differences between the two, one marked by a focus on regulations and authority and the other by a focus on data collection and preparedness. Understanding these institutional differences promotes a better understanding of how adaptive governance can be iteratively applied in novel ecosystems to improve management under rapidly changing conditions.

Predator-Induced Nocturnal Benthic Emergence: Field and Experimental Evidence for an Unknown Behavioral Escape Mechanism along the Coral Reef–Seagrass Interface

Previously, using plankton tows, and emergence and settlement traps, we documented persistent widespread nocturnal emergence, and planktonic redistribution, of benthic macroinvertebrates along the coral reef–seagrass interface at two geographically separated locations. We also documented that emergence intensity varies with distance from the reef, leading us to hypothesize that the spatial pattern of emergence is determined by the foraging patterns of nocturnally active, bottom-feeding, mid-level consumers (mainly grunts). In this second study, we coupled those previously published data with nocturnal fish surveys concurrently conducted along belt transects placed at the same locations as the emergence trap collections, and a controlled laboratory experiment, to test this hypothesis. The results of these analyses find that variability in the density of nocturnally active, bottom-feeding fish is strongly positively correlated with emergence intensity, regardless of site or season. Results from the laboratory experiments show that nocturnal invertebrate emergence is significantly higher in the presence of one bottom-feeding fish (the blue-striped grunt Haemulon sciurus) than in microcosms that do not contain this predator. Overall, this study shows that such processes may explain how benthic prey can avoid capture by nocturnally active, bottom-feeding predators and persist in the predator-rich seagrass habitats that surround coral reefs in the Florida Keys National Marine Sanctuary. This study also points out the need to consider nocturnal processes when studying seagrass biodiversity in a predator-rich environment.

Spatiotemporal Variation in Coral Assemblages and Reef Habitat Complexity among Shallow Fore-Reef Sites in the Florida Keys National Marine Sanctuary

With the unprecedented degradation and loss of coral reefs at multiple scales, the underlying changes in abiotic and biotic features relevant to the three-dimensional architecture of coral reefs are critical to conservation and restoration. This study characterized the spatiotemporal variation of habitat metrics at eight fore-reef sites representing three management zones in the Florida Keys, USA using visual habitat surveys (2017–2018) acquired before and after Hurricane Irma. Post-hurricane, five of those sites were surveyed using structure-from-motion photogrammetry to further investigate coral morphology on structural complexity. Multivariate results for visual surveys identified moderate separation among sites, with fished sites characterized by complex physical features such as depth and vertical hard relief while protected sites generally harbored high abundances of live coral cover. Three-dimensional models of mapped sites showed within site variation as another driver in site separation. Additionally, fine-scale orthoimage analyses identified significant differences in dominant coral morphologies at each mapped site. This study suggests protected reef sites generally harbor higher live coral cover despite some fished sites being structurally similar in seabed topography. Our work provides fine-scale spatial data on several managed sites within a marine sanctuary and highlights the contribution of diverse coral assemblages to the coral reef framework.

Updating the Florida Keys National Marine Sanctuary Management Plan: Estimating the Impact to Commercial Fishing in Monroe County, Florida

This article is designed to provide the methodologies used to estimate the impact to the commercial fishing industry as a result of spatial zone management changes within Florida Keys National Marine Sanctuary and its study area, Monroe County, FL. The analysis provided here provides a template for how to estimate economic impacts when refined human use spatial data are not available. Utilizing existing habitat maps and economic data, this method downscales traditional economic methods using a spatial approach to match the fine-scale management approach utilized by the National Marine Sanctuary System. This approach allows the authors to estimate the economic impacts to the commercial fishing sector. The authors find that the proposed spatial zone changes may result in an estimated loss of 42 jobs, with 28 being harvester jobs, to the state of Florida. Additionally, $4.1 million in output and approximately $1.1 million in income may be lost. These estimates do not take into account the likelihood of substitution to alternative fishing grounds or adjusting the target species.

Economic Contributions of Visitor Spending in Ocean Recreation in the Florida Keys National Marine Sanctuary

Understanding the economic value of marine sanctuaries such as the Florida Keys National Marine Sanctuary (FKNMS) is important to justify public and private investments and to provide information to support management activities and understand their role in the nation’s blue economy. Very few studies have employed economic contribution analysis in examining economic value, even though it is more useful in influencing the behaviors of decision makers. This study therefore employs such a methodology to determine the economic importance of tourism and visitor spending in the sanctuary to Monroe County, Florida’s economy. Visitors who came to the area for ocean recreation and tourism spent a total of USD 1.7 billion, which translates to a contribution of 19,688 total jobs, USD 752 million in total labor income, USD 1.2 billion in total value added, and USD 2 billion in total output to the region. With regard to the spending of snorkelers and divers only, total spending is about USD 1.07 billion, contributing about 12,441 total jobs, USD 466 million in total labor income, USD 767 million in total value added, and USD 1.2 billion in total output. Ocean recreation is therefore an important economic driver in the region and efforts should be directed at protecting the diverse and sensitive ecosystem of the sanctuary.

User Satisfaction and Crowding at Florida Keys National Marine Sanctuary

Effective management and monitoring of recreational use is fundamental in marine protected areas. The primary purpose of this study is to examine user’s satisfaction levels, crowding levels and the relationship between them at Florida Keys National Marine Sanctuary. Online surveys were sent via Qualtrics to email addresses obtained from the state of Florida during the summer of 2020. The results showed that the respondents felt very satisfied and only slightly crowded while snorkeling or scuba diving during their most recent 2019 trip in the Florida Keys, although satisfaction was still negatively impacted by crowding. An analysis of variance (ANOVA) showed that satisfaction levels were significantly lower in users who saw more people than they expected. A linear regression indicated significantly lower satisfaction with increasing age. Furthermore, a multiple regression showed that experiencing natural surroundings has a significant positive relationship in overall trip satisfaction, i.e., users that are more satisfied experiencing natural surroundings are also likely to be more satisfied with their overall trip satisfaction. This study suggests that the convergence of social and natural resource research and practices can help managers to create better policies that will maximize human benefits from, and minimize human pressures on, ocean and coastal environments.

Reef-Fish Abundance, Biomass, and Biodiversity Inside and Outside No-Take Marine Zones in the Florida Keys National Marine Sanctuary: 1999–2018

Observations from the Reef Visual Census program in the Florida Keys National Marine Sanctuary (FKNMS) between 1999 and 2018 were used as a US Marine Biodiversity Observation Network case study to assess whether differences in biodiversity metrics (abundance, biomass, richness, Simpson diversity, and functional diversity) occurred across regions with different habitat types (high-relief, linear, and patch reefs), protection levels (no-take and unprotected zones), and types of protected zones. Protected areas had higher reef-fish biomass compared to unprotected areas at the beginning of the observation period, but these metrics decreased over time. We did not detect an effect of size of no-take marine zones, but rather found that large (18.7 km2) and small (average of 0.85 km2) areas had similar reef-fish abundance, biomass, and diversity indices. High-relief reef habitats had the greatest reef-fish abundance (20%–30%) and species richness (~20%), and nearly twice the biomass of other habitat strata, but biomass decreased 20%–30% in linear and patch reefs after 2007. Although high-relief reefs are important for biodiversity conservation and restoration, policies should address the decline in fish abundance, biomass, and diversity observed throughout the FKNMS. Monitoring should be sustained to support policies and respond to changing conditions related to climate change and resource use.

A quantitative and qualitative decision-making process for selecting indicators to track ecosystem condition

Ecosystem indicators are a well-established method for tracking ecosystem conditions and trends with the purpose of informing ecosystem-based management. The selection of indicators is a key step in the management process; however, because 1) selection can be inherently subjective 2) researchers can be entrenched in the ecosystem components they routinely measure, and 3) some voices may be marginalized in a group setting, the selection, prioritization, and consensus processes can be challenging. To overcome these issues, an indicator selection process was developed herein that incorporated expert opinion both qualitatively and quantitatively. The decision matrix asked experts to provide weighted values for each selection criterion and a score of how well each potential indicator fit each criterion. The score of how well the indicators fit the criterion was multiplied by the weight given to that criterion, then summed for all criteria, resulting in an overall score of how well a potential indicator fit the criteria. The indicator scores were then ranked using all experts’ scores to develop a single best-fit list of indicators. The approach was pilot-tested to select indicators for the Florida Keys National Marine Sanctuary (FKNMS), creating a prioritized list of indicators that best reflected the condition of the FKNMS resources, ecosystem services, and pressures. Specifically, 56 indicators were found to best model the status and trends associated with 16 standard questions regarding condition of national marine sanctuaries. This process is directly transferable to other national marine sanctuaries, and also identifies data gaps. The criteria can be modified to make the selection process applicable to a wide range of ecosystem-based management applications in both marine and terrestrial ecosystems. This method provides a means of selecting indicators that minimizes the effects of group dynamics on consensus.

Examining the dynamic nature of epiphytic microalgae in the Florida Keys: What factors influence community composition?

The factors that influence the composition of marine epiphytic microalgal assemblages are poorly-understood. To address this short-coming, 93 samples were collected from four distinct regions in the Florida Keys National Marine Sanctuary (FKNMS) during winter and summer months to test the model that epiphytic microalgal communities are influenced by environmental gradients related to different sites, seasons, and host macrophyte species. One hundred and eighty-three morphotypes from 13 classes (7 phyla) were identified, dominated by 106 Bacillariophyta (77 identified to species equivalent or below), 37 Cyanophyta (13 identified to species equivalent or below), and 30 Dinophyta (21 identified to species equivalent or below). The largest proportion of variability in epiphytic communities was related to physico-chemical parameters (37%), followed by site location (ocean- versus bayside; 15%), seasonal differences (11%), and host macrophyte species (10%). Four physico-chemical variables were found to be most influential: wave height, temperature, ammonium concentration, and salinity. Only six out of 616 epiphyte – host comparisons exhibited significant differences in individual epiphyte taxon abundance between different host species (within site and season), further demonstrating that host-specificity was not strongly evident in this study. Overall, the results of this (sub)tropical study indicate that changing environmental characteristics between sites and seasons were the primary drivers influencing epiphyte community composition. Similar findings were found in an accompanying study of phytoplankton and other studies from temperate and (sub)polar regions, suggesting that common, underlying processes exist among these disparate environments.

Identifying mangrove-coral habitats in the Florida Keys.

Coral reefs are degrading due to many synergistic stressors. Recently there have been a number of global reports of corals occupying mangrove habitats that provide a supportive environment or refugium for corals, sheltering them by reducing stressors such as oxidative light stress and low pH. This study used satellite imagery and manual ground-truthing surveys to search for mangrove-coral habitats in the Florida Keys National Marine Sanctuary and then collected basic environmental parameters (temperature, salinity, dissolved oxygen, pHNBS, turbidity) at identified sites using a multi-parameter water quality sonde. Two kinds of mangrove-coral habitats were found in both the Upper and Lower Florida Keys: (1) prop-root corals, where coral colonies were growing directly on (and around) mangrove prop roots, and (2) channel corals, where coral colonies were growing in mangrove channels under the shade of the mangrove canopy, at deeper depths and not in as close proximity to the mangroves. Coral species found growing on and directly adjacent to prop roots included Porites porites (multiple morphs, including P. divaricata and P. furcata), Siderastrea radians, and Favia fragum. Channel coral habitats predominantly hosted S. radians and a few S. siderea, although single colonies of Solenastrea bournoni and Stephanocoenia intersepta were observed. Although clear, low-turbidity water was a consistent feature of these mangrove-coral habitats, the specific combination of environmental factors that determine which mangrove habitats are favorable for coral recruitment remains to be defined. Circumstantial evidence suggests additional coral communities existed on mangrove shorelines of oceanside and backcountry islands until destroyed, likely by Hurricane Irma. These mangrove-coral habitats may be climate refugia for corals and could be included in ecosystem management plans and considered for their applications in coral restoration.

Dynamic Satellite Seascapes as a Biogeographic Framework for Understanding Phytoplankton Assemblages in the Florida Keys National Marine Sanctuary, United States

Physical, chemical, geological, and biological factors interact in marine environments to shape complex but recurrent patterns of organization of life on multiple spatial and temporal scales. These factors define biogeographic regions in surface waters that we refer to as seascapes. We characterize seascapes for the Florida Keys National Marine Sanctuary (FKNMS) and southwest Florida shelf nearshore environment using multivariate satellite and in situ measurements of Essential Ocean Variables (EOVs) and Essential Biodiversity Variables (EBVs). The study focuses on three periods that cover separate oceanographic expeditions (March 11-18, May 9-13, and September 12-19, 2016). We collected observations on bio-optical parameters (particulate and dissolved spectral absorption coefficients), phytoplankton community composition, and hydrography from a ship. Phytoplankton community composition was evaluated using 1) chemotaxonomic analysis (CHEMTAX) based on high-performance liquid chromatography (HPLC) pigment measurements, and 2) analysis of spectral phytoplankton absorption coefficients (aphy). Dynamic seascapes were derived by combining satellite time series of sea surface temperature, chlorophyll-a concentration, and normalized fluorescent line height (nFLH) using a supervised thematic classification. The seascapes identified areas of different salinity and nutrient concentrations where different phytoplankton communities were present as determined by hierarchical cluster analyses of HPLC pigments and aphy spectra. Oligotrophic, Mesotrophic and Transition seascape classes of deeper offshore waters were dominated by small phytoplankton ( 60 %). Spectral analysis of aphy indicated higher absorption levels at 492 and 550 nm wavelengths in seascapes carrying predominantly small phytoplankton than in classes dominated by larger taxa. Seascapes carrying large phytoplankton showed absorption peaks at the 673 nm wavelength. The seascape framework promises to be a tool to detect different biogeographic domains quickly, providing information about the changing environmental conditions experienced by coral reef organisms including coral, sponges, fish and higher trophic levels. The effort illustrates best practices developed under the Marine Biodiversity Observation Network (MBON) demonstration project, in collaboration with the South Florida Ecosystem Restoration Research (SFER) project managed by the Atlantic Oceanographic and Meteorological Laboratory of NOAA (AOML-NOAA).

Survivorship and growth in staghorn coral (Acropora cervicornis) outplanting projects in the Florida Keys National Marine Sanctuary.

Significant population declines in Acropora cervicornis and A. palmata began in the 1970s and now exceed over 90%. The losses were caused by a combination of coral disease and bleaching, with possible contributions from other stressors, including pollution and predation. Reproduction in the wild by fragment regeneration and sexual recruitment is inadequate to offset population declines. Starting in 2007, the Coral Restoration Foundation™ evaluated the feasibility of outplanting A. cervicornis colonies to reefs in the Florida Keys to restore populations at sites where the species was previously abundant. Reported here are the results of 20 coral outplanting projects with each project defined as a cohort of colonies outplanted at the same time and location. Photogrammetric analysis and in situ monitoring (2007 to 2015) measured survivorship, growth, and condition of 2419 colonies. Survivorship was initially high but generally decreased after two years. Survivorship among projects based on colony counts ranged from 4% to 89% for seven cohorts monitored at least five years. Weibull survival models were used to estimate survivorship beyond the duration of the projects and ranged from approximately 0% to over 35% after five years and 0% to 10% after seven years. Growth rate averaged 10 cm/year during the first two years then plateaued in subsequent years. After four years, approximately one-third of surviving colonies were ≥ 50 cm in maximum diameter. Projects used three to sixteen different genotypes and significant differences did not occur in survivorship, condition, or growth. Restoration times for three reefs were calculated based on NOAA Recovery Plan (NRP) metrics (colony abundance and size) and the findings from projects reported here. Results support NRP conclusions that reducing stressors is required before significant population growth and recovery will occur. Until then, outplanting protects against local extinction and helps to maintain genetic diversity in the wild.

Sound science, not politics, must inform restoration of Florida Bay and the coral reefs of the Florida Keys

The comment by Julian (2020) criticizes aspects of our paper, “Nitrogen enrichment, altered stoichiometry, and coral reef decline at Looe Key, Florida Keys, USA.” The comment begins by misrepresenting our extensive literature review, while providing no justification for the claim of a “skewed reading.” Julian’s critique focused on methods of data handling, statistics, and spatial awareness, which we demonstrate in every case to be either irrelevant or incorrect. We provide additional supporting data that refute these claims. For example, Julian criticized the removal of data points below the method detection limits (MDLs), but when these points are included, the results do not change. Further, Julian criticized our removal of outliers, but so few points were excluded that it did not change the results of the statistical analyses. Julian also misinterpreted the methods of our correlation and stepwise regression analyses but did not dispute the Kruskal–Wallis tests of our 30-year dataset that revealed significant decadal changes. Julian’s closing paragraph is replete with misinformation and demonstrates a lack of understanding as to how increased freshwater flows associated with Everglades Restoration have led to a worsening of algal blooms and coral decline in the Florida Keys National Marine Sanctuary (FKNMS). This comment represents a smokescreen to confuse the scientific community about the physical connectivity of the Everglades basin and the FKNMS. Past water management policies based on politics, not sound science, have caused irreparable and ongoing environmental damage to sensitive coral reef communities in the FKNMS.

Assessment of Hurricane Irma Impacts on South Florida Seagrass Communities Using Long-Term Monitoring Programs

Hurricanes are some of the largest environmental drivers of change in coastal systems. We investigated the impacts of Hurricane Irma on benthic macrophyte communities in Florida Bay (FB) and the Florida Keys National Marine Sanctuary (FKNMS), USA. Spatiotemporal analyses were performed at multiple hierarchical levels (site, zone, region) to identify potential changes in the Braun-Blanquet (BB) densities of total seagrass (TSG) and total calcareous green macroalgae (TCAL) post-disturbance and to determine whether changes were attributable to hurricane impacts or normal seasonal and inter-annual variability. There were significant decreases in TSG in one of five zones in FKNMS and in one of six zones in FB, but no change in TCAL was recorded in either system. TSG in the Lower Keys Bayside declined from a mean BB score of 2.6 to 1.2, resulting from storm-induced erosion, whereas TSG in coastal FB declined from 1.05–2.4 to 0.36–2.0, likely due to prolonged hyposalinity and low dissolved oxygen following stormwater drainage. Overall, impacts to South Florida benthic macrophyte communities from Hurricane Irma were not catastrophic and were limited in spatial extent. Our results suggest that coastal areas hit by a storm with heavy winds are more likely to sustain direct physical impacts to the benthos, whereas estuarine areas with longer residence times are more at risk of the indirect effects of stormwater runoff and retention. Our analyses placed putative hurricane impacts within the context of recent variability and historical system baselines through the use of long-term monitoring data coordinated by multiple governmental and academic entities.

Saharan dust deposition initiates successional patterns among marine microbes in the Western Atlantic

AbstractDeposition of aerosolized desert dust can affect marine microbial community structure and function through pulsed addition of limiting micro‐ and macronutrients. However, few studies have captured responses to dust deposition in situ following trans‐oceanic transport. We conducted a 26‐d time series evaluating biogeochemical and microbial community response to Saharan dust deposition in surface waters in the subtropical western Atlantic (Florida Keys National Marine Sanctuary, U.S.A.). Following periods of elevated atmospheric dust concentrations, particulate and dissolved iron concentrations increased in surface waters. Autotrophic picoeukaryote abundance increased rapidly, followed by increases in the abundance of heterotrophic bacteria and Synechococcus. Concomitant to cell count changes, we observed successional shifts in bacterial community composition. The relative abundances of Prochlorococcus and Pelagibacter declined with dust arrival, while relative abundance of heterotrophic bacteria increased, beginning with Vibrionales and followed sequentially by Chrysophyceae, Rhodobacteriaceae, and Flavobacteriaceae. Finally, a peak in Synechococcus cyanobacteria was observed. These results provide new insight into microbial community succession in response to Saharan dust deposition, their association with temporal dynamics in surface water dissolved and particulate iron concentrations, and a potential role for bioprocessing of dust particles in shaping marine microbial responses to deposition events.

Impacts of consecutive bleaching events and local algal abundance on transplanted coral colonies in the Florida Keys

Climate change threatens many marine ecosystems, including coral reefs and the thousands of organisms that inhabit these reefs. Fluctuations in sea surface temperatures trigger bleaching events in coral colonies that lead to increased coral mortality and reef degradation. To combat the decline in coral cover, many researchers have focused on transplanting coral colonies to better understand which species are best adapted to these environmental changes. This current study examined the impacts of two consecutive thermal stress events on transplanted coral colonies in the middle Florida Keys within the Florida Keys National Marine Sanctuary. Coral fragments of two species (Porites astreoides and Siderastrea siderea) were transplanted on seven reef sites. Transplanted colonies were monitored for evidence of coral bleaching during quarterly sampling trips from June 2013 through June 2017. Bleaching was only observed during the late summer of 2014 and 2015 when Degree Heating Weeks exceeded 4 °C-weeks. Results indicate that P. astreoides colonies had significantly higher bleaching than S. siderea colonies. Reefs differed in their proportion of bleached and unbleached corals for P. asteroides, but these reefs did not differ in their average daily maximum temperature or Degree Heating Weeks. However, individual corals that did bleach had a higher average fleshy algal abundance (Dictyota spp.) surrounding them than those corals that remained unbleached. Corals that bleached the first year and survived were no more or less likely to bleach the second year. These findings suggest that resilience to bleaching differs not only by coral species but may also be influenced by the local abundance of fleshy algal species.

Assessing eukaryotic biodiversity in the Florida Keys National Marine Sanctuary through environmental DNA metabarcoding.

Environmental DNA (eDNA) is the DNA suspended in the environment (e.g., water column), which includes cells, gametes, and other material derived from but not limited to shedding of tissue, scales, mucus, and fecal matter. Amplifying and sequencing marker genes (i.e., metabarcoding) from eDNA can reveal the wide range of taxa present in an ecosystem through analysis of a single water sample. Metabarcoding of eDNA provides higher resolution data than visual surveys, aiding in assessments of ecosystem health. This study conducted eDNA metabarcoding of two molecular markers (cytochrome c oxidase I (COI) and 18S ribosomal RNA (rRNA) genes) to survey eukaryotic diversity across multiple trophic levels in surface water samples collected at three sites along the coral reef tract within the Florida Keys National Marine Sanctuary (FKNMS) during four research cruises in 2015. The 18S rRNA gene sequences recovered 785 genera while the COI gene sequences recovered 115 genera, with only 33 genera shared between the two datasets, emphasizing the complementarity of these marker genes. Community composition for both genetic markers clustered by month of sample collection, suggesting that temporal variation has a larger effect on biodiversity than spatial variability in the FKNMS surface waters. Sequences from both marker genes were dominated by copepods, but each marker recovered distinct phytoplankton groups, with 18S rRNA gene sequences dominated by dinoflagellates and COI sequences dominated by coccolithophores. Although eDNA samples were collected from surface waters, many benthic species such as sponges, crustaceans, and corals were identified. These results show the utility of eDNA metabarcoding for cataloging biodiversity to establish an ecosystem baseline against which future samples can be compared in order to monitor community changes.

Evaluation of marine zooplankton community structure through environmental DNA metabarcoding.

Zooplankton dominate the abundance and biomass of multicellular animals in pelagic marine environments; however, traditional methods to characterize zooplankton communities are invasive and laborious. This study compares zooplankton taxonomic composition revealed through metabarcoding of the cytochrome oxidase I (COI) and 18S rRNA genes to traditional morphological identification by microscopy. Triplicates of three different sample types were collected from three coral reef sites in the Florida Keys National Marine Sanctuary: (1) 1 L surface seawater samples prefiltered through 3 μm filters and subsequently collected on 0.22 μm filters for eDNA (PF‐eDNA); (2) 1 L surface seawater samples filtered on 0.22 μm pore‐size filters (environmental DNA; eDNA), and (3) zooplankton tissue samples from 64 μm, 200 μm, and 500 μm mesh size net tows. The zooplankton tissue samples were split, with half identified morphologically and tissue DNA (T‐DNA) extracted from the other half. The COI and 18S rRNA gene metabarcoding of PF‐eDNA, eDNA, and T‐DNA samples was performed using Illumina MiSeq. Of the families detected with COI and 18S rRNA gene metabarcoding, 40% and 32%, respectively, were also identified through morphological assessments. Significant differences in taxonomic composition were observed between PF‐DNA, eDNA, and T‐DNA with both genetic markers. PF‐eDNA resulted in detection of fewer taxa than the other two sample types; thus, prefiltering is not recommended. All dominant copepod taxa (> 5% of total abundance) were detected with eDNA, T‐DNA, and morphological assessments, demonstrating that eDNA metabarcoding is a promising technique for future biodiversity assessments of pelagic zooplankton in marine systems.

Christ of the Abyss, Florida Keys National Marine Sanctuary, Key Largo, Florida, U.S.A.

<i>Christ of the Abyss</i>, Florida Keys National Marine Sanctuary, Key Largo, Florida, U.S.A.

Non-native molluscan colonizers on deliberately placed shipwrecks in the Florida Keys, with description of a new species of potentially invasive worm-snail (Gastropoda: Vermetidae).

Artificial reefs created by deliberately sinking ships off the coast of the Florida Keys island chain are providing new habitat for marine invertebrates. This newly developing fouling community includes the previously reported invasive orange tube coral Tubastraea coccinea and the non-native giant foam oyster Hyotissa hyotis. New SCUBA-based surveys involving five shipwrecks spanning the upper, middle, and lower Florida Keys, show T. coccinea now also established in the lower Keys and H. hyotis likewise extending to new sites. Two additional mollusks found on the artificial reefs, the amathinid gastropod Cyclothyca pacei and gryphaeid oyster Hyotissa mcgintyi, the latter also common in the natural reef areas, are discussed as potentially non-native. A new species of sessile, suspension-feeding, worm-snail, Thylacodes vandyensis Bieler, Rawlings & Collins n. sp. (Vermetidae), is described from the wreck of the USNS Vandenberg off Key West and discussed as potentially invasive. This new species is compared morphologically and by DNA barcode markers to other known members of the genus, and may be a recent arrival from the Pacific Ocean. Thylacodes vandyensis is polychromatic, with individuals varying in both overall head-foot coloration and mantle margin color pattern. Females brood stalked egg capsules attached to their shell within the confines of their mantle cavity, and give rise to crawl-away juveniles. Such direct-developing species have the demonstrated capacity for colonizing habitats isolated far from their native ranges and establishing rapidly growing founder populations. Vermetid gastropods are common components of the marine fouling community in warm temperate and tropical waters and, as such, have been tagged as potentially invasive or with a high potential to be invasive in the Pacific Ocean. As vermetids can influence coral growth/composition in the Pacific and have been reported serving as intermediate hosts for blood flukes of loggerhead turtles, such new arrivals in the Florida Keys National Marine Sanctuary are of concern. Growing evidence indicates that artificial reefs can act as permanent way-stations for arriving non-natives, providing nurseries within which populations may grow in an environment with reduced competition compared to native habitats. Consequently, artificial reefs can act as sentinels for the appearance of new species. Ongoing monitoring of the developing molluscan fauna on the artificial reefs of the Florida Keys is necessary to recognize new invasions and identify potential eradication targets, thereby assuring the health of the nearby natural barrier reef.