Benthic community dynamics and stony coral demographics in Florida in relation to acute disturbances and chronic pressures

The persistence of coral reef communities is threatened by a suite of pressures operating at varying spatial and temporal scales. In general, acute disturbances (short term stochastic events such as marine heatwaves or hurricanes) and chronic pressures, such as ocean warming, have caused the most significant changes to stony coral assemblages (order Scleractinia) and continue to impair recovery potential. Additionally, many coral reefs are subject to local chronic anthropogenic pressures resulting in poor water quality or sedimentation, which further impact stony corals and shape benthic community structure, particularly near urbanized coastlines. For the viability of communities on coral reefs, a balance must be struck between loss following disturbance and recovery (i.e., resilience). The current scientific consensus is that under moderate disturbance regimes, locations subject to less local chronic anthropogenic pressure will be more resilient and the community will recover during inter-disturbance periods. However, given observed and predicted increases in the frequency and severity of acute disturbances under global climate change, resilience may be undermined regardless of contemporary differences in local chronic pressure. Florida’s Coral Reef (FCR), stretching 595km from St Lucie Inlet to the Dry Tortugas, exists along a gradient of chronic anthropogenic pressure and was impacted by multiple acute disturbances over the past two decades. This study explored benthic community dynamics and stony coral demographic processes, such as recruitment, growth and mortality, to assess the influence of acute disturbances and chronic pressures on FCR. Spatiotemporal changes in the benthic community from 2004 to 2018 and stony coral resilience were assessed in relation to acute disturbances, in the three distinct coral reef regions on the FCR: the high-latitude, heavily urbanized Southeast Florida Coral Reef Ecosystem Conservation Area (ECA), the governmentally protected, but historically exploited Florida Keys and the comparatively remote, least exploited Dry Tortugas (Chapter 1). In the ECA, spatiotemporal variations in net growth rates and partial mortality were quantitively analyzed in the three most abundant coral species, Montastraea cavernosa, Porites astreoides and Siderastrea siderea from 2000 to 2020 (Chapter 2). The influence of water quality and temperature on benthic community composition and interannual changes in stony coral abundance, recruitment, mortality and diversity were analyzed in the ECA from 2018 to 2021, a period with no known acute disturbances (Chapter 3). Finally, spatiotemporal variations in recruitment, density and size structure of the contemporary stony coral assemblage were assessed in the ECA from 2018 to 2022 (Chapter 4) Overall, stony coral resilience was found to be low across the FCR, regardless of differences in chronic pressure, with significant declines in cover during periods with acute disturbances, limited recovery during inter-disturbance periods and corresponding proliferation of macroalgae. High partial and whole colony mortality, predominately related to acute disturbances and stony coral tissue loss disease, constrained net growth rates in M. cavernosa, P. astreoides and S. siderea, such that colonies reached just a third of their potential size. Recruitment was generally low in the ECA, averaging 0.95 ±0.2 recruits m-2 (± SE). Siderastrea siderea recruitment was high at some inshore sites (~7 recruits m-2), but there was limited evidence these survived or grew into larger size classes. Spatial decoupling between recruitment, size structure and survival likely maintains a preponderance of small colonies in the ECA. Higher water temperature, particularly when annual mean water temperature was above 27 °C, was positively associated with stony coral recruitment, abundance and health, until threshold maximum temperatures were exceeded (\u3e31 °C). The benefits associated with warmer temperatures were negated by poor water quality, as nutrient enrichment was related to increased macroalgae cover, reduced coral recruitment and higher partial mortality. At present the future for stony corals in Florida is bleak. High acute disturbance frequency, from a multitude of different stressors, and chronic environmental pressures were related to consistent declines in cover, high partial colony mortality which constrains growth and a degraded coral community composed of small colonies, primarily of weedy or resistant species. However, the data suggests reducing local chronic pressures in the ECA may limit increases in macroalgae cover and enhance stony coral recovery potential during inter-disturbance periods, particularly when temperatures are optimal. Urgent action to tackle global climate change and local anthropogenic pressures is therefore required for these coral communities to have any realistic prospect of recovery

Spatiotemporal Change in the Benthic Community of Southeast Florida

High-latitude reefs have been postulated as refugia, centers for resilience or the first areas to undergo re-organization under climate change. The Southeast Florida Reef Tract (SEFRT) is a high-latitude reef system (\u3e25 °N) running parallel to the highly urbanized coastline of southeast Florida. With a benthic community comprised of a mixture of coral reef associated assemblages, the SEFRT is towards the northern limit of stony coral cover due to temperature constraints. This study analyzed spatial variations in benthic cover, spatiotemporal changes in the benthic community and the impact of spatial and temporal fluctuations in temperature on benthic cover on the SEFRT, from 2007-2016. Photographic data from two long term monitoring projects was used to calculate the percent cover of taxonomic assemblages in the benthic community. In situ temperature data and modelled data from HYCOM were used in combination to assess the impact of temperature fluctuations and thermal stress events. Data was split on a latitudinal gradient into six defined ecosystem regions based on biogeographic boundaries and at major port channels. These accounted for any possible range expansion and spatiotemporal variations on the SEFRT. Statistical analysis via generalized linear models (GLM) identified significant changes in the major benthic taxa, stony coral, octocoral, sponges and macroalgae. Ecosystem regions showed strong clustering by their taxonomic composition and this was in part created by temperature variation. Stony coral cover significantly declined on the SEFRT and a concomitant significant increase in macroalgae cover may create a negative feedback loop which hinders recovery. Spatiotemporal variations in benthic cover were found between ecosystem regions and thermal stress events, both hot and cold, had immediate and latent impacts on benthic cover. This has resulted in biotic homogenization on the SEFRT with a retraction of outlier regions towards the mean. Anthropogenically influenced high-latitude reefs are significantly impacted by thermal stress. As oceans continue to warm, populations expand, coastlines continue to develop and pollutants persist, the benefits of potential thermal refugia are negated

Error-proof programmable self-assembly of DNA-nanoparticle clusters

We study theoretically a new generic scheme of programmable self-assembly of nanoparticles into clusters of desired geometry. The problem is motivated by the feasibility of highly selective DNA-mediated interactions between colloidal particles. By analyzing both a simple generic model and a more realistic description of a DNA-colloidal system, we demonstrate that it is possible to suppress the glassy behavior of the system, and to make the self-assembly nearly error-proof. This regime requires a combination of stretchable interparticle linkers (e.g. sufficiently long DNA), and a soft repulsive potential. The jamming phase diagram and the error probability are computed for several types of clusters. The prospects for the experimental implementation of our scheme are also discussed. PACS numbers: 81.16.Dn, 87.14.Gg, 36.40.EiComment: 6 pages, 4 figures, v2: substantially revised version, added journal re

Thermal Stress-Related Spatiotemporal Variations in High-Latitude Coral Reef Benthic Communities

High-latitude coral reef communities have been postulated as the first areas to undergo reorganisation under climate change. Tropicalisation has been identified in some high-latitude communities and is predicted in others, but it is unclear how the resident benthic taxa are affected. We conducted a long-term (2007–2016) assessment of changes to benthic community cover in relation to thermal stress duration on the Southeast Florida Reef Tract (SEFRT). Thermal stress events, both hot and cold, had acute (thermal stress duration affected benthic cover that year) and chronic (thermal stress duration affected benthic cover the following year) impacts on benthic cover. Chronic heat stress was associated with declines in cover of the reef-building coral families Acroporidae, Montastraeidae, Meandrinidae, Mussidae and Siderastreidae, which coupled with the absence of cold stress and rising annual temperatures boosted macroalgae cover. Cover of smaller, weedy coral families, Poritidae, Agariciidae and Astrocoeniidae, was either unaffected or positively related to heat stress duration and rising mean temperature. Thermal stress was related to spatiotemporal variations in benthic cover on the SEFRT, likely enhanced by local stressors, such as elevated nutrients and sedimentation. Coral and octocoral cover declined within four of six sub-regions, sponge cover increased in half of the sub-regions, and macroalgae cover increased in four sub-regions during the study. Under current conditions, increased macroalgae and weedy coral cover are anticipated to inhibit reef recovery

Temperature stress and disease drives the extirpation of the threatened pillar coral, Dendrogyra cylindrus, in southeast Florida

Rare species population dynamics can elucidate the resilience of an ecosystem. On coral reefs, climate change and local anthropogenic stressors are threatening stony coral persistence, increasing the need to assess vulnerable species locally. Here, we monitored the threatened pillar coral, Dendrogyra cylindrus, population in southeast Florida, USA, in relation to consecutive heat stress events in 2014 and 2015. In the fall of each year, D. cylindrus colonies bleached following intense thermal stress and by June 2020 all monitored colonies died from a white-syndrome type disease. This resulted in the ecological extinction of D. cylindrus in the Southeast Florida Coral Reef Ecosystem Conservation Area (ECA). White-syndrome type disease was first seen in February 2014 on four colonies (19% prevalence) near the major international port, Port Everglades and disease prevalence peaked in fall 2015 (58%). Disease prevalence increased with maximum water temperature, while disease related mortality increased with mean water temperature. Our findings suggest that thermal stress exacerbated underlying stony coral disease, resulting in an outbreak contributing to the ecological extirpation of D. cylindrus in the ECA. We suggest that stony coral resilience is severely compromised by chronic environmental disturbance which hinders community recovery

Environmental Assessment of Soil for Monitoring: Volume IIb Survey of National Networks

The ENVASSO Project (Contract 022713) was funded 2006-8, under the European Commission 6th Framework Programme of Research, with the objective of defining and documenting a soil monitoring system appropriate for soil protection at continental level. The ENVASSO Consortium, comprising 37 partners drawn from 25 EU Member States, reviewed almost 300 soil indicators, identified existing soil inventories and monitoring programmes in the Member States, designed and programmed a database management system to capture, store and supply soil profile data, and drafted procedures and protocols appropriate for inclusion in a European soil monitoring network of sites that are geo-referenced and at which a qualified sampling process is or could be conducted. This volume (IIb), a Survey of National Networks, is the second of two reports that together constitute the most comprehensive study to date of the soil inventory and monitoring activities in the European Union. It contains comprehensive fact sheets for each national network, listing the purpose, sampling strategy adopted, analytical methods used and the number of monitoring sites.JRC.H.7-Climate Risk Managemen

Using coupled micropillar compression and micro-Laue diffraction to investigate deformation mechanisms in a complex metallic alloy Al13Co4

In this investigation, we have used in-situ micro-Laue diffraction combined with micropillar compression of focused ion beam milled Al13Co4 complex metallic alloy to study the evolution of deformation in Al13Co4. Streaking of the Laue spots showed that the onset of plastic flow occured at stresses as low as 0.8 GPa, although macroscopic yield only becomes apparent at 2 GPa. The measured misorientations, obtained from peak splitting, enabled the geometrically necessary dislocation density to be estimated as 1.1 x 1013 m-2

Rapid Assessment of Southern Pine Decayed by G. Trabeum by Near Infrared Spectra Collected from the Radial Surface

The use of near infrared (NIR) spectroscopy for predicting levels of degradation in southern pine (Pinus spp.) by Gloeophyllum trabeum for periods over 1-8 da was investigated. NIR spectra collected from the center of the radial face of each sample after laboratory soil block decay tests were used to develop calibrations. Calibrations were developed for mass loss, compression strength, and exposure period using data measured from prior methods and untreated and mathematically treated (multiplicative scatter correction and first and second derivative) NIR spectra from various ranges of wavelengths by partial least squares regression. Strong relationships were derived from the calibrations with the strongest R2 values of 0.97 (exposure period), 0.94 (compression strength), and 0.91 (mass loss). Calibrations for exposure period showed the strongest statistics for predicting wood decay of the validation test set (R2 = 0.92; RPDp [ratio of the standard deviation of the measured data to the standard error of prediction] = 3.95 [first derivative, 1100-2250 nm]), while predictions for mass loss of the decayed samples resulted in R2 = 0.86 and an RPDp = 3.17 (multiplicative scatter correction, 1100-2500 nm), and the strongest compression strength prediction resulted in R2 = 0.76 and an RPDp = 2.50 (second derivative, 1100-2500 nm). These results suggest that NIR spectroscopy can adequately predict wood decay from spectra collected from the radial face of southern pine

048— Sibling Relationship Quality in Emerging Adulthood: A Phenomenological Study of Latinx College Students

This phenomenological research examined Latinx college students’ sibling relationships in emerging adulthood. Researchers developed and employed a coding schema based on the work of Buhrmester and Furman (1987) to code for relationship quality. A thematic analysis revealed differences in relationship quality based on participants’ culture identity

Deglacial grounding-line retreat in the Ross Embayment, Antarctica, controlled by ocean and atmosphere forcing

Modern observations appear to link warming oceanic conditions with Antarctic ice sheet grounding-line retreat. Yet, interpretations of past ice sheet retreat over the last deglaciation in the Ross Embayment, Antarctica’s largest catchment, differ considerably and imply either extremely high or very low sensitivity to environmental forcing. To investigate this, we perform regional ice sheet simulations using a wide range of atmosphere and ocean forcings. Constrained by marine and terrestrial geological data, these models predict earliest retreat in the central embayment and rapid terrestrial ice sheet thinning during the Early Holocene. We find that atmospheric conditions early in the deglacial period can enhance or diminish ice sheet sensitivity to rising ocean temperatures, thereby controlling the initial timing and spatial pattern of grounding-line retreat. Through the Holocene, however, grounding-line position is much more sensitive to subshelf melt rates, implicating ocean thermal forcing as the key driver of past ice sheet retreat