916 research outputs found
The importance of habitat quality for marine reserve fishery linkages
We model marine reserve - fishery linkages to evaluate the potential contribution of habitat-quality improvements inside a marine reserve to fish productivity and fishery catches. Data from Mombasa Marine National Park, Kenya, and the adjacent fishery are used. Marine reserves increase total fish biomass directly by providing refuge from exploitation and indirectly by improving fish habitat in the reserve. As natural mortality of the fish stock decreases in response to habitat enhancement in the reserve, catches increase by up to 2.6 tonnes (t).km(-2).year(-1) and total fish biomass by up to 36 t.km(-2). However, if habitat-quality improvement reduces the propensity of fish to move out of the reserve, catches may fall by up to 0.9 t.km(-2).year(-1). Our results indicate that habitat protection in reserves can underpin fish productivity and, depending on its effects on fish movements, augment catches
Assessing Gear Modifications Needed to Optimize Yields in a Heavily Exploited, Multi-Species, Seagrass and Coral Reef Fishery
Effective management is necessary if small-scale fisheries, such as those found in mixed habitats including seagrass and coral reefs, are to continue providing food for many of the poorest communities of the world. Gear-based management, although under represented and under studied, has the potential to be adaptive, address multiple objectives, and be crafted to the socio-economic setting. Management effectiveness in seagrass and coral reef fisheries has generally been evaluated at the scale of the fish community. However, community level indicators can mask species-specific declines that provide significant portions of the fisheries yields and income. Using a unique dataset, containing ten years of species level length frequency catch data from a multi-gear, multi-species seagrass and coral reef fishery in Kenya, we evaluate species specific fishery statuses, compare gear use to gear regulations and estimate the potential needs for further gear restrictions. Despite the high diversity of the fishery, fifteen species represented over 90% of the catch, and only three species represented 60% of the catch. The three most abundant species in the catch, Lethrinus lentjan (Lacepède), Siganus sutor (Valenciennes) and Leptoscarus vaigiensis (Quoy & Gaimard) all showed evidence of growth overfishing. Lethrinus lentjan, with an exploitation rate of 0.82, also shows evidence of recruitment overfishing. Current legal but weakly enforced gear restrictions are capable of protecting a significant portion of the catch up to maturity but optimization of yield will require that the current mesh size be increased from 6.3 to 8.8 and 9.2 cm to increase yields of L. lentjan and S. sutor, respectively. Given the difficulties of enforcing mesh size, we recommend that the economic benefits of these larger mesh sizes be communicated and enforced through co-management. This abstract is also available in Kiswahili (Abstract S1)
UnSub: Sundry Thoughts, Employing Data from the Wiley e-Journal Package
The authors reviewed the UnSub tool using journal download data from Wiley for 2020. Some of the lead author\u27s concerns with cancelling the Wiley journal package and proceeding with UnSub\u27s Open Access-dependent approach are detailed
Wiley Journal Package: UNL Download Activity by Subject
Because the field of librarianship has been reconsidering its relationship to commercial academic publishers and their \u27Big Deal\u27 journal packages, the authors decided to review the University of Nebraska-Lincoln\u27s usage of Wiley\u27s package. In this report, the authors looked into whether UNL\u27s downloads by subject were such that subscribing to a number of hypothetical smaller, subject-specific packages, rather than to the entire Wiley package, might be a viable strategy
Scaling Up Video Digitization at the University of Maryland Libraries: A Case Study
In 2015, a team at the University of Maryland Libraries collaborated on a pilot project to digitize 100 VHS tapes from the Liz Lerman Dance Exchange collection and, in doing so, established organizational workflows for video digitization and access. After completing the pilot phase of the project, staff who worked on the project published a case study in this journal that articulated a question echoed throughout that process: “Is this enough?” Enough descriptive metadata? Enough technical metadata? Enough storage space? This article will reflect on the pilot project, detail how the digitization specifications and workflows established during the pilot project have changed over the intervening years, and how they were scaled-up to digitize and make accessible the remaining videos 1,125 videos in the collection under the auspices of a 2018 National Endowment for the Humanities grant
Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems
Coral reefs have emerged as one of the ecosystems most vulnerable to climate variation and change. While the contribution
of a warming climate to the loss of live coral cover has been well documented across large spatial and temporal scales, the
associated effects on fish have not. Here, we respond to recent and repeated calls to assess the importance of local
management in conserving coral reefs in the context of global climate change. Such information is important, as coral reef
fish assemblages are the most species dense vertebrate communities on earth, contributing critical ecosystem functions
and providing crucial ecosystem services to human societies in tropical countries. Our assessment of the impacts of the
1998 mass bleaching event on coral cover, reef structural complexity, and reef associated fishes spans 7 countries, 66 sites
and 26 degrees of latitude in the Indian Ocean. Using Bayesian meta-analysis we show that changes in the size structure,
diversity and trophic composition of the reef fish community have followed coral declines. Although the ocean scale
integrity of these coral reef ecosystems has been lost, it is positive to see the effects are spatially variable at multiple scales,
with impacts and vulnerability affected by geography but not management regime. Existing no-take marine protected areas
still support high biomass of fish, however they had no positive affect on the ecosystem response to large-scale disturbance.
This suggests a need for future conservation and management efforts to identify and protect regional refugia, which should
be integrated into existing management frameworks and combined with policies to improve system-wide resilience to
climate variation and change
Comparison of Image Restoration Methods for Lunar Epithermal Neutron Emission Mapping
Orbital measurements of neutrons by the Lunar Exploring Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter are being used to quantify the spatial distribution of near surface hydrogen (H). Inferred H concentration maps have low signal-to-noise (SN) and image restoration (IR) techniques are being studied to enhance results. A single-blind. two-phase study is described in which four teams of researchers independently developed image restoration techniques optimized for LEND data. Synthetic lunar epithermal neutron emission maps were derived from LEND simulations. These data were used as ground truth to determine the relative quantitative performance of the IR methods vs. a default denoising (smoothing) technique. We review and used factors influencing orbital remote sensing of neutrons emitted from the lunar surface to develop a database of synthetic "true" maps for performance evaluation. A prior independent training phase was implemented for each technique to assure methods were optimized before the blind trial. Method performance was determined using several regional root-mean-square error metrics specific to epithermal signals of interest. Results indicate unbiased IR methods realize only small signal gains in most of the tested metrics. This suggests other physically based modeling assumptions are required to produce appreciable signal gains in similar low SN IR applications
Comparison of Marine Spatial Planning Methods in Madagascar Demonstrates Value of Alternative Approaches
The Government of Madagascar plans to increase marine protected area coverage by over one million hectares. To assist this process, we compare four methods for marine spatial planning of Madagascar's west coast. Input data for each method was drawn from the same variables: fishing pressure, exposure to climate change, and biodiversity (habitats, species distributions, biological richness, and biodiversity value). The first method compares visual color classifications of primary variables, the second uses binary combinations of these variables to produce a categorical classification of management actions, the third is a target-based optimization using Marxan, and the fourth is conservation ranking with Zonation. We present results from each method, and compare the latter three approaches for spatial coverage, biodiversity representation, fishing cost and persistence probability. All results included large areas in the north, central, and southern parts of western Madagascar. Achieving 30% representation targets with Marxan required twice the fish catch loss than the categorical method. The categorical classification and Zonation do not consider targets for conservation features. However, when we reduced Marxan targets to 16.3%, matching the representation level of the “strict protection” class of the categorical result, the methods show similar catch losses. The management category portfolio has complete coverage, and presents several management recommendations including strict protection. Zonation produces rapid conservation rankings across large, diverse datasets. Marxan is useful for identifying strict protected areas that meet representation targets, and minimize exposure probabilities for conservation features at low economic cost. We show that methods based on Zonation and a simple combination of variables can produce results comparable to Marxan for species representation and catch losses, demonstrating the value of comparing alternative approaches during initial stages of the planning process. Choosing an appropriate approach ultimately depends on scientific and political factors including representation targets, likelihood of adoption, and persistence goals
The Interplanetary Network Supplement to the BeppoSAX Gamma-Ray Burst Catalogs
Between 1996 July and 2002 April, one or more spacecraft of the
interplanetary network detected 787 cosmic gamma-ray bursts that were also
detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera
experiments aboard the BeppoSAX spacecraft. During this period, the network
consisted of up to six spacecraft, and using triangulation, the localizations
of 475 bursts were obtained. We present the localization data for these events.Comment: 89 pages, 3 figures. Submitted to the Astrophysical Journal
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