Biscayne National Park

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BACKGROUND: Coral reefs are facing increasing pressure from natural and anthropogenic stressors that have already caused significant worldwide declines. In January 2010, coral reefs of Florida, United States, were impacted by an extreme cold-water anomaly that exposed corals to temperatures well below their reported thresholds (16°C), causing rapid coral mortality unprecedented in spatial extent and severity. METHODOLOGY/PRINCIPAL FINDINGS: Reef surveys were conducted from Martin County to the Lower Florida Keys within weeks of the anomaly. The impacts recorded were catastrophic and exceeded those of any previous disturbances in the region. Coral mortality patterns were directly correlated to in-situ and satellite-derived cold-temperature metrics. These impacts rival, in spatial extent and intensity, the impacts of the well-publicized warm-water bleaching events around the globe. The mean percent coral mortality recorded for all species and subregions was 11.5% in the 2010 winter, compared to 0.5% recorded in the previous five summers, including years like 2005 where warm-water bleaching was prevalent. Highest mean mortality (15%-39%) was documented for inshore habitats where temperatures were <11°C for prolonged periods. Increases in mortality from previous years were significant for 21 of 25 coral species, and were 1-2 orders of magnitude higher for most species. CONCLUSIONS/SIGNIFICANCE: The cold-water anomaly of January 2010 caused the worst coral mortality on record for the Florida Reef Tract, highlighting the potential catastrophic impacts that unusual but extreme climatic events can have on the persistence of coral reefs. Moreover, habitats and species most severely affected were those found in high-coral cover, inshore, shallow reef habitats previously considered the "oases" of the region, having escaped declining patterns observed for more offshore habitats. Thus, the 2010 cold-water anomaly not only caused widespread coral mortality but also reversed prior resistance and resilience patterns that will take decades to recover.

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Climate and soil conditions in South Florida along with an extensive canal system facilitate movement of agricultural pesticides into surface waters. In a two-year study (2002-2004) of the currently used pesticides in South Florida, atrazine, endosulfan, metolachlor, chlorpyrifos, and chlorothalonil were the most frequently detected in the canals and in Biscayne Bay, with average concentrations of 16, 11, 9.0, 2.6, and 6.0 ng/L, respectively. Concentrations of atrazine and chlorpyrifos were highest near corn production. Chlorothalonil and endosulfan concentrations were highest near vegetable production, with no clear trend for metolachlor, which is used on multiple crops. Concentration data were used to calculate an aquatic life hazard potential for the planting period (November) versus the harvest period (March). This analysis indicated that a higher hazard potential occurs during harvest, primarily from the use of endosulfan. These data will also serve to document canal conditions prior to implementation of the Comprehensive Everglades Restoration Plan (CERP).

In 2023, a record-setting marine heat wave triggered the ninth mass coral bleaching event on Florida’s Coral Reef (FCR). We examined spatial patterns of heat exposure along the ~560-kilometer length of FCR and the mortality of two ecologically important, critically endangered reef-building corals. Sea surface temperatures were ≥31°C for an average of 40.7 days, leading to heat exposures 2.2- to fourfold higher than all prior years on record. In the Florida Keys and Dry Tortugas, 97.8 to 100% of the Acropora palmata and Acropora cervicornis colonies died. Mortality was lower offshore southeast Florida (37.9%), reflecting cooler temperatures in this region. Since the late 1970s, multiple stressors had already reduced the ecological relevance of Acropora in Florida, but the 2023 heat wave marks their functional extinction from FCR.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 540:27-41 (2015) - DOI: https://doi.org/10.3354/meps11505 Impacts of physical disturbance on ecosystem structure in subtropical seagrass meadows Amanda S. Bourque1,2,*, W. Judson Kenworthy3, James W. Fourqurean2 1Habitat Restoration Program, Biscayne National Park, National Park Service, Homestead, FL 33033, USA 2Marine Science Program, Department of Biological Sciences, and Southeast Environmental Research Center, Florida International University, Miami, FL 33199, USA 3109 Holly Lane, Beaufort, NC 28516, USA *Corresponding author: amanda_bourque@nps.gov ABSTRACT: Soil disturbance, a key contributor to physical degradation in seagrass ecosystems, can lead to long-term changes in ecosystem function. We used a chronosequence of vessel grounding disturbances of different ages (0 yr, 1 yr, 3 yr, 4 yr, 5+ yr) as a model for soil disturbance to test hypotheses that disturbance alters primary producer communities, soil properties, biogeochemical processes, and infauna communities in seagrass ecosystems and that altered structure and processes will change following disturbance through seagrass bed development and ecosystem recovery. Disturbance involving excavated surface soils resulted in long-term loss of seagrass and macroalgae and stored organic carbon, nitrogen, and phosphorus. Disturbed sites were characterized by reductions in variables related to organic matter and inorganic nutrient content. Disturbance altered habitat quality for some taxa including amphipods, as evident from differences in invertebrate community structure. These impacts persisted in study sites for 5+ yr after the disturbance, likely because of physical and chemical soil modification accompanied by slow development of the seagrass community. We estimate that disturbance from 0.4 m deep excavations led to losses of 6.0 kg m-2 organic C (Corg), 0.4 kg m-2 N, and 0.03 kg m-2 P from the disturbed areas. First-order conservative estimates of scarring excavation rate in Miami-Dade County, Florida, USA, suggest potential annual fluxes of 1.1 × 106 kg Corg, 74000 kg N, and 5500 kg P from seagrass soils in the region. Our findings suggest that vessel grounding disturbances create complex and long-term resource losses that are undervalued by resource trustees. KEY WORDS: Ecosystem function · Blue carbon · Nitrogen · Phosphorus · Infauna · Macroalgae · Biscayne National Park · Soil · Sediment Full text in pdf format Supplementary material PreviousNextCite this article as: Bourque AS, Kenworthy WJ, Fourqurean JW (2015) Impacts of physical disturbance on ecosystem structure in subtropical seagrass meadows. Mar Ecol Prog Ser 540:27-41. https://doi.org/10.3354/meps11505 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 540. Online publication date: November 26, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

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Ocean warming is increasing the frequency, extent, and severity of tropical-coral bleaching and mortality. During 2014-2017, marine heatwaves caused the Third Global Coral Bleaching Event. We analyze data from 15,066 reef surveys globally during 2014-2017. Across all surveyed reefs, 80% and 35% experienced moderate or greater (affecting >10% of corals) bleaching and mortality, respectively. We assess the global extent of coral bleaching and mortality by applying bleaching response curves calibrated from surveyed reefs to predict bleaching globally, based on comprehensive remote-sensing of heat stress. These models predict that 51% and 15% of the world's coral reefs suffered moderate or greater bleaching and mortality, respectively, during one or multiple years, surpassing damage from any prior global coral bleaching event. Our findings demonstrate that the impacts of ocean warming on coral reefs are accelerating, with the near certainty that ongoing warming will cause large-scale, possibly irreversible, degradation of these essential ecosystems. With heat stress levels during this event surpassing those observed previously, the National Oceanic and Atmospheric Administration developed more extreme Bleaching Alert levels that are now being used during the ongoing Fourth Global Coral Bleaching Event.

Microorganisms in seagrass sediments facilitate many key ecosystem processes, yet current knowledge of microbial facilitation of seagrass community recovery following disturbance or restoration is limited. We studied microbial community responses to restoration of a subtropical seagrass meadow disturbed by vessel groundings in south Florida, USA, and relationships between microbial communities and sediment properties at the study sites using terminal restriction fragment length polymorphism. Two restoration methods were evaluated: the installation of bird roosting stakes as a means to provide a nutrient source, and placement of sand fill into excavations to prevent erosion. Both disturbed and restoration sites had less complex microbial community structure than undisturbed reference seagrass sediments. Microbial community structure varied little between disturbed and fertilized sites, but was distinct in filled sites. Sediment bulk density, sediment organic matter and total phosphorus content, porewater ammonium, soluble reactive phosphorus, and dissolved sulfide concentrations were important environmental predictors of microbial community structure across the restoration treatments. We show that community structure and diversity varied with sediment depth, among restoration treatments, and through time. Our results indicate that microbial communities in seagrass meadows are changed by physical disturbance of the rhizosphere, and that common restoration techniques lead to the formation of distinct microbial communities during the first year of recovery.

Fishery managers must understand the dynamics of fishers and their prey to successfully predict the outcome of management actions. We measured the impact of a two-day exclusively recreational fishery on Caribbean spiny lobster in the Florida Keys, USA, over large spatial scales (>100 km) and multiple years and used a theoretical, predator-prey functional response approach to identify whether or not sport diver catch rates were density-independent (type I) or density-dependent (type II or III functional response), and if catch rates were saturated (i.e., reached an asymptote) at relatively high lobster densities. We then describe how this predator-prey framework can be applied to fisheries management for spiny lobster and other species. In the lower Keys, divers exhibited a type-I functional response, whereby they removed a constant and relatively high proportion of lobsters (0.74-0.84) across all pre-fishing-season lobster densities. Diver fishing effort increased in a linear manner with lobster prey densities, as would be expected with a type-I functional response, and was an order of magnitude lower in the upper Keys than lower Keys. There were numerous instances in the upper Keys where the density of lobsters actually increased from before to after the fishing season, suggesting some type of "spill-in effect" from surrounding diver-disturbed areas. With the exception of isolated reefs in the upper Keys, the proportion of lobsters removed by divers was density independent (type-I functional response) and never reached saturation at natural lobster densities. Thus, recreational divers have a relatively simple predatory response to spiny lobster, whereby catch rates increase linearly with lobster density such that catch is a reliable indicator of abundance. Although diver predation is extremely high (approximately 80%), diver predation pressure is not expected to increase proportionally with a decline in lobster density (i.e., a depensatory response), which could exacerbate local extinction. Furthermore, management actions that reduce diver effort should have a concomitant and desired reduction in catch. The recreational diver-lobster predator-prey construct in this study provides a useful predictive framework to apply to both recreational and commercial fisheries, and on which to build as management actions are implemented.

Exploitation impacts and management options for 15 coral reef fish species central to the commercial and recreational fisheries of the southern Florida USA coral reef ecosystem were evaluated using a length-based risk analysis (LBRA) framework. Population abundance-at-length composition data were obtained from several regional federal-state sampling programs. These and updated life history demographic data were integrated into a length-based numerical cohort model to generate LBRA fishery sustainability metrics from a probabilistic perspective. Three of five groupers, eight of eight snappers, and two of two grunts were below the 40% spawning potential ratio (SPR) stock sustainability minimum; ten of these stocks are at < 20% of their historical spawning biomass, some as low as 5%. Therefore, to ameliorate overfishing for the 13 stocks with sustainability risks ≥ 98%, fisheries management requires increased minimum sizes of first capture Lc and significant reductions in fishing mortality F. To achieve sustainability and reduce sustainability risks area-time protections are also needed. While lack of data often limits the evaluation of management options, this paper establishes benchmarks from which data-limited approaches can move forward. In addition, the approach can be used to cross-check other data-rich analyses. A goal of this work is to effectively balance sustainability risks with fishery production to mitigate overfishing likelihoods and to increase the probability of sustainable fisheries.

Abstract Designing effective local management for invasive species poses a major challenge for conservation, yet factors affecting intervention success and efficiency are rarely evaluated and incorporated into practice. We coordinated regional efforts by divers to cull invasive lionfish ( Pterois spp.) on 33 U.S. Atlantic, Gulf of Mexico, and Caribbean protected coral reefs from 2013 to 2019 and estimated removal efficiency and efficacy as a function of environmental and habitat conditions, invasion status, and personnel expertise. Highly experienced individuals culling during crepuscular periods (<2 hr from sunrise/sunset) are three times more efficient (in terms of minutes) than novice divers during midday, suggesting: (a) retention of experienced individuals is key for efficient programs, and (b) planning culls with personnel and time of day in mind increases the number of sites covered with the same effort. Lionfish behavior and habitat characteristics had little effect on removal efficiency and efficacy, but divers had higher capture success at reefs with higher lionfish densities. We suggest reefs with persistently <20 fish ha −1 as low priority, given that impacts to native fauna are unlikely and culling effectiveness declines to <50% below this level. Incorporating efficiency factors in spatial management planning along with density estimates derived from remotely sensed data can ensure limited resources for control are extended across a greater range of invaded habitats.

Coral reefs in the Florida Keys are severely degraded with a reported 38% loss between 1996 and 2000, yet the causes of these devastating declines remain largely unknown. Our long-term studies in the Upper Keys and Biscayne National Park indicate acute stress events affecting physiological condition in species representing different trophic levels in the reef community, one of which was white grunt (Haemulon plumieri; Lacépède, 1801). We initiated a preliminary investigation describing cellular physiological stress effects and the possible causes of these stress events using cellular diagnostic profiling coupled with a cursory body-load contaminant chemistry analysis. The cellular biomarker profiles from fish taken from Alina's Reef indicated a toxic response profile that was suggestive of a suicide reaction of the cytochrome P450 2-class as a result of an interaction with a xenobiotic that adversely affects heme metabolism. Elevated levels of damaged porphyrin products were also found in fish from Alina's Reef. Liver loads of anthropogenic contaminants (e.g., pesticides, PCBs) were measured and provided further evidence for possible causative agents. Evaluation and synthesis of each type of data were used to establish a biological effect, develop a mechanism of pathogenicity, and build a profile for possible causative agent(s).

The Biscayne and Southern Everglades Coastal Transport (BISECT) model was developed

The sea urchin embryo development toxicity test was used to investigate toxicity of the benthic substrate in Biscayne National Park (BISC). Twenty-five sites were selected based upon a high potential for anthropogenic stressor input (e. g., hydrocarbons, personal care products, nutrients, etc.) or proximity to coral reef habitats. We found that sediment interstitial water (porewater) was toxic to urchin embryos at 22 of 25 sites. Healthy sites included two coral reefs (Anniversary Reef and Marker 14 Reef) and Turkey Point Channel. Discrete areas of BISC have highly toxic sediments and the presence of sediment contaminants could negatively impact reproduction, growth and population density of benthic invertebrates, such as corals. Results of the sea urchin embryo development toxicity test can be used as a baseline assessment for monitoring improvements or degradation in ecosystem health and could be a valuable tool to investigate the suitability of degraded habitats for future reef restoration. Since the last comprehensive environmental assessment of BISC was performed in 1999, further investigation into the sources of toxicity at BISC is needed.

An unprecedented marine heatwave in 2023 caused widespread coral bleaching and mortality throughout the Caribbean. In the Florida Keys (USA), 2 foundation species, elkhorn coral (Acropora palmata) and staghorn coral (Acropora cervicornis), were severely affected. These species have been the primary focus of reef restoration in Florida for decades. Substantial losses of these species occurred in outplanted populations, in ocean-based nurseries, and among remnant wild colonies, leading to uncertainty over their future in the Florida Keys, given recent observed trends in climate conditions. However, the past 2 decades of restoration activity created a community of experts, a network of ocean-based and land-based coral-rearing infrastructure, and 2 independent land-based coral gene banks that prevented regional extirpation and preserved much of the genetic richness of these critically endangered coral species. Without the past decades of effort and the emergency response associated with the 2023 bleaching event, Florida acroporids would largely have been lost. This outcome afforded by the restoration network in Florida demonstrates the value of proactively establishing resources prior to major disturbances. We identified several critical strategies that, in the context of existing climate change, are preventing the extirpation of coral species in Florida, including extending collaborative restoration efforts to solidify a network of trained experts; establishing trust-focused relationships among management agencies and restoration groups; testing direct interventions to reduce light and temperature stress early during thermal anomalies; developing redundant ocean-based and land-based nurseries; and establishing living coral gene banks prior to major threats to prevent the extirpation of coral species.

As stony coral tissue loss disease (SCTLD) has spread across Florida's Coral Reef (FCR), there has been an emphasis on restoring the losses in coral cover through outplanting. This research is part of a larger project assessing the efficacy of restoring SCTLD‐susceptible corals Montastraea cavernosa (great star coral), Orbicella faveolata (mountainous star coral), and Pseudodiploria clivosa (knobby brain coral) in SCTLD enzootic areas. As part of Florida's largest coral restoration experiment to date, 1,165 cement bases with 5,825 coral fragments from 99 source colonies were outplanted across 6 regions throughout FCR and monitored monthly over 2 years for survival, disease, and growth. Before outplanting, coral tissue samples were collected for genotyping and initial algal symbiont analysis using 2bRAD and ITS2 sequencing. Neither host genetic lineages nor pre‐deployment algal symbiont types significantly predicted SCTLD susceptibility, disputing the hypothesis of SCTLD‐resistant “super coral” lineages. Overall, SCTLD prevalence remained low on outplanted colonies during the first 14 months post‐outplanting. This study suggests that current restoration efforts should not be constrained by concerns over SCTLD‐related losses. Given the absence of evidence for SCTLD‐resistant lineages in the species we tested, efforts should continue to focus on promoting genetic diversity among outplanted corals.

Patterns of survivorship and growth of rescued boulder corals from two vessel groundings in Biscayne National Park, Homestead, Florida, U.S.A., were evaluated over 5 years and compared to nearby undamaged reference corals. The rescued colonies had been dislodged but reattached in situ 10–12 years later (hereafter termed “restored” corals). Change in live coral tissue area was assessed using novel contoured tissue measurements which proved useful in detecting small changes in tissue area for slow‐growing coral species. At the initial survey, restored boulder corals had a higher level of partial mortality (33.8 ± 3.1%, mean ± SE) relative to reference corals (19.9 ± 2.5%), likely a result of prolonged detachment. During the course of the 5‐year monitoring period, whole‐colony mortality was greater for restored corals (13.1%) compared to reference corals (3.3%). For surviving corals, restored coral growth and recent mortality rates were similar to reference corals even though restored corals, especially those of Dichocoenia stokesii, had greater disease prevalence (19.7%) than reference corals (6.6%). These results suggest that dislodged boulder coral rescue following an acute disturbance can be an effective tool in stemming tissue loss. If dislodged corals were reattached in a more timely manner, we predict that the survival and tissue growth would be greater.

Biological invasions threaten ecosystems worldwide, with invasive predators such as lionfish (Pterois spp.) altering marine communities through predation, competition, and habitat disruption. Since their introduction to the western Atlantic in the 1980s, lionfish have rapidly expanded their range and contributed to declines in native reef fish populations. In response, management agencies have implemented targeted removal programs, although their effectiveness, particularly across broad spatial and temporal scales, remains uncertain. We evaluated the effects of removals (culls) at two temporal frequencies by quantifying the densities of both lionfish and potential prey over two years at experimental and non-removal control sites in Florida's Biscayne National Park (BNP). Removals conducted at one-month intervals resulted in moderate reductions in lionfish density but removals at four-month removals did not result in appreciable changes in density. Neither treatment produced substantial changes in lionfish biomass or native prey abundance. Importantly, the magnitude of change in lionfish density following removals depended on the initial lionfish density at a site. Together with previous work, these results suggest that removals are less effective at reducing lionfish densities and enhancing prey assemblages once lionfish densities are already low. Our findings underscore the importance of monitoring lionfish density when evaluating the ecological efficacy of removal programs.

Biological invasions threaten ecosystems worldwide, with invasive predators such as lionfish (Pterois spp.) altering marine communities through predation, competition, and habitat disruption. Since their introduction to the western Atlantic in the 1980s, lionfish have rapidly expanded their range and contributed to declines in native reef fish populations. In response, management agencies have implemented targeted removal programs, although their effectiveness—particularly across broad spatial and temporal scales—remains uncertain. We evaluated the effects of culling at varying frequencies by quantifying the densities of both lionfish and potential prey over multiple years at culled and undisturbed sites in Florida’s Biscayne National Park (BNP). Culls conducted at one- or four-month intervals resulted in moderate reductions in lionfish density but did not produce substantial changes in lionfish biomass or native prey abundance. Importantly, the magnitude of change in lionfish density following culling depended on initial lionfish density at a site. Together with previous work, these results suggest that culling is less effective at reducing lionfish densities and enhancing prey assemblages once lionfish densities are already low. Our findings underscore the importance of monitoring lionfish density when evaluating the ecological efficacy of removal programs.