The effects of docks on seagrasses, with particular emphasis on the threatened seagrass, Halophila johnsonii

In March of 2005, the National Oceanic and Atmospheric Administration's Special Projects Office released "Population Trends along the Coastal United States: 1980-2008." This report includes population changes and trends between 1980 and 2003 and projected changes in coastal populations by 2008. Given the findings, pressure on coastal resources around the country will continue to rise, particularly in Florida. ... One of our most valuable coastal resources is seagrass, but human desire and need to live on the coast means that our habitat overlaps with suitable seagrass habitat. Seagrasses can be found in coastal areas around the world but are limited to relatively shallow, relatively clear water because of their reliance on light for photosynthesis. Seagrasses provide food for both small and large marine organisms, larval and adult stage. They provide shelter and habitat to a variety of commercially important fish and invertebrates. They baffle the water column and inhibit the resuspension of sediments. They prevent erosion and fix and recycle nutrients. The physical and ecological benefits of seagrasses make them very important to human welfare, but their light-limited coastal distribution makes them highly susceptible to anthropogenic influences

Changes in the distribution and density of Florida Bay macrophytes: 1995-2004

Benthic macrophyte cover and distribution data have been collected in ten basins within Florida Bay since 1995 as part of the Florida Bay Fisheries Habitat Assessment Program (FHAP). A weighted average for the most prevalent macrophytes during each sampling event since spring 1995 was calculated. Results indicate that the three most common seagrasses observed in Florida Bay, Thalassia testudinum, Halodule wrightii, and Syringodium filiforme, have increased in distribution since 1995. Halodule wrightii and Syringodium filiforme exhibited an increase in both frequency and cover at the bay-scale, an occurrence driven by their dramatic increases in the western-most FHAP study basins: Johnson and Rabbit Key Basins. Acetabularia, Batophora, Halimeda, and Penicillus also exhibited increases in both frequency and cover since spring 1995. The drift Rhodophytes increased in density and distribution between spring 1995 and spring 1998, but did not increase further after that time. Batophora proved to be the most ubiquitous macroalgae throughout Florida Bay and Acetabularia and the drift Rhodophytes showed the strongest seasonal fluctuations, as they were both much more abundant and widespread during spring samplings. Spearman rank order correlation analysis of the Braun-Blanquet cover data showed that Thalassia was generally negatively correlated to all other macrophytes, while Halodule, Halophila, and Syringodium were positively correlated to one another on most occasions. These seagrasses fluctuated between positive and negative correlations with the macroalgae, and as a group, the macroalgae were positively correlated with one another on most occasions, although exceptions did apply. Non-metric multidimensional scaling was used to create ordination plots of the ~ 315 sample stations. Density overlays were used in conjunction with these ordination plots, and together these showed that total seagrass cover and total macroalgal cover were generally mutually exclusive. Spearman rank order correlation analysis was further used to determine if this spatial separation of the two macrophyte groups was statistically significant at the bay-scale, and it was found that 11 of the 18 bi-annual sampling events yielded a statistically significant negative correlation between total seagrass cover and total macroalgae cover. Canonical Correspondence Analysis (CCA) was used to determine which, if any, of the environmental/physical variables, collected as part of the FHAP data set, had a significant effect on macrophyte distribution within Florida Bay. Significance of these effects was determined using Monte Carlo Permutation Tests. CCA showed that depth and visibility were the initial driving forces in macrophyte distribution. During fall 2000, however, a spike in salinity was observed and by spring 2001 this became the most significant variable affecting macrophyte distribution, and it remained so, along with depth, throughout the duration of FHAP

Submersed Aquatic Vegetation in Chesapeake Bay: Sentinel Species in a Changing World

Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, SAV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, SAV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of SAV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem

Long-term Annual Aerial Surveys of Submersed Aquatic Vegetation (SAV) Support Science, Management, and Restoration

Aerial surveys of coastal habitats can uniquely inform the science and management of shallow, coastal zones, and when repeated annually,theyrevealchangesthatareotherwisedifficulttoassess fromground-basedsurveys.Thispaperreviewstheutilityofalongterm(1984–present)annualaerialmonitoringprogramforsubmersedaquaticvegetation(SAV)inChesapeakeBay,itstidaltributaries, and nearby Atlantic coastal bays, USA. We present a series of applications that highlight the program’s importance in assessing anthropogenic impacts, gauging water quality status and trends, establishing and evaluating restoration goals, and understanding the impactofcommercialfishingpracticesonbenthichabitats.Theseexamplesdemonstratehowperiodicallyquantifyingcoverageofthis important foundational habitat answers basic research questions locally, as well as globally, and provides essential information to resource managers. New technologies are enabling more frequent and accurate aerial surveys at greater spatial resolution and lower cost. These advances will support efforts to extend the applications described here to similar issues in other areas

IRSA's New Look: Design Considerations

The NASA/IPAC Infrared Science Archive (IRSA) undertook a major upgrade to its website and user experience this year. The work was motivated by the need to facilitate access to a growing number of astronomical data sets and exploration tools. The guiding principle of the redesign was to focus on the most important items, while providing easy access to the full set of IRSA's holdings and services. We discuss the redesign process and the key features of the new website

The Zwicky Transient Facility: Data Processing, Products, and Archive

The Zwicky Transient Facility (ZTF) is a new robotic time-domain survey currently in progress using the Palomar 48-inch Schmidt Telescope. ZTF uses a 47 square degree field with a 600 megapixel camera to scan the entire northern visible sky at rates of ~3760 square degrees/hour to median depths of g ~ 20.8 and r ~ 20.6 mag (AB, 5sigma in 30 sec). We describe the Science Data System that is housed at IPAC, Caltech. This comprises the data-processing pipelines, alert production system, data archive, and user interfaces for accessing and analyzing the products. The realtime pipeline employs a novel image-differencing algorithm, optimized for the detection of point source transient events. These events are vetted for reliability using a machine-learned classifier and combined with contextual information to generate data-rich alert packets. The packets become available for distribution typically within 13 minutes (95th percentile) of observation. Detected events are also linked to generate candidate moving-object tracks using a novel algorithm. Objects that move fast enough to streak in the individual exposures are also extracted and vetted. The reconstructed astrometric accuracy per science image with respect to Gaia is typically 45 to 85 milliarcsec. This is the RMS per axis on the sky for sources extracted with photometric S/N >= 10. The derived photometric precision (repeatability) at bright unsaturated fluxes varies between 8 and 25 millimag. Photometric calibration accuracy with respect to Pan-STARRS1 is generally better than 2%. The products support a broad range of scientific applications: fast and young supernovae, rare flux transients, variable stars, eclipsing binaries, variability from active galactic nuclei, counterparts to gravitational wave sources, a more complete census of Type Ia supernovae, and Solar System objects.Comment: 30 pages, 16 figures, Published in PASP Focus Issue on the Zwicky Transient Facility (doi: 10.1088/1538-3873/aae8ac

The Zwicky Transient Facility: System Overview, Performance, and First Results

The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides a 47 deg 2 field of view and 8 s readout time, yielding more than an order of magnitude improvement in survey speed relative to its predecessor survey, the Palomar Transient Factory. We describe the design and implementation of the camera and observing system. The ZTF data system at the Infrared Processing and Analysis Center provides near-real-time reduction to identify moving and varying objects. We outline the analysis pipelines, data products, and associated archive. Finally, we present on-sky performance analysis and first scientific results from commissioning and the early survey. ZTF’s public alert stream will serve as a useful precursor for that of the Large Synoptic Survey Telescope

The Zwicky Transient Facility: Science Objectives

The Zwicky Transient Facility (ZTF), a public–private enterprise, is a new time-domain survey employing a dedicated camera on the Palomar 48-inch Schmidt telescope with a 47 deg2 field of view and an 8 second readout time. It is well positioned in the development of time-domain astronomy, offering operations at 10% of the scale and style of the Large Synoptic Survey Telescope (LSST) with a single 1-m class survey telescope. The public surveys will cover the observable northern sky every three nights in g and r filters and the visible Galactic plane every night in g and r. Alerts generated by these surveys are sent in real time to brokers. A consortium of universities that provided funding (“partnership”) are undertaking several boutique surveys. The combination of these surveys producing one million alerts per night allows for exploration of transient and variable astrophysical phenomena brighter than r∼20.5 on timescales of minutes to years. We describe the primary science objectives driving ZTF, including the physics of supernovae and relativistic explosions, multi-messenger astrophysics, supernova cosmology, active galactic nuclei, and tidal disruption events, stellar variability, and solar system objects. © 2019. The Astronomical Society of the Pacific

The Zwicky Transient Facility: System Overview, Performance, and First Results

The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides a 47 deg^2 field of view and 8 s readout time, yielding more than an order of magnitude improvement in survey speed relative to its predecessor survey, the Palomar Transient Factory. We describe the design and implementation of the camera and observing system. The ZTF data system at the Infrared Processing and Analysis Center provides near-real-time reduction to identify moving and varying objects. We outline the analysis pipelines, data products, and associated archive. Finally, we present on-sky performance analysis and first scientific results from commissioning and the early survey. ZTF's public alert stream will serve as a useful precursor for that of the Large Synoptic Survey Telescope

Manual Point Cloud Classification and Extraction for Hunter-Gatherer Feature Investigation: A Test Case From Two Low Arctic Paleo-Inuit Sites

For archaeologists, the task of processing large terrestrial laser scanning (TLS)-derived point cloud data can be difficult, particularly when focusing on acquiring analytical and interpretive outcomes from the data. Using our TLS lidar data collected in 2013 from two compositionally different, low Arctic multi-component hunter-gatherer sites (LdFa-1 and LeDx-42), we demonstrate how a manual point cloud classification approach with open source software can be used to extract natural and archaeological features from a site’s surface. Through a combination of spectral datasets typical to TLS (i.e., intensity and RGB values), archaeologists can enhance the visual and analytical representation of archaeological huntergatherer site surfaces. Our approach classifies low visibility Arctic site point clouds into independent segments, each representing a different surface material found on the site. With the segmented dataset, we extract only the surface boulders to create an alternate characterization of the site’s prominent features and their surroundings. Using surface point clouds from Paleo-Inuit sites allows us to demonstrate the value of this approach within hunter-gatherer research as our results illustrate an effective use of large TLS datasets for extracting and improving our analytical capabilities for low relief site features