Moseley C.,University of Cape Town |
Gremillet D.,University of Cape Town |
Gremillet D.,French National Center for Scientific Research |
Connan M.,University of Cape Town |
And 11 more authors.
Journal of Experimental Marine Biology and Ecology | Year: 2012
Using a multi-disciplinary approach, we evaluated the potential consequences of long-term contrasting prey availability on the condition Cape gannets Morus capensis. We compared breeding adults from a decreasing colony on Malgas Island off the west coast of South Africa, where the abundance of small pelagic fish has decreased, with an increasing colony on Bird Island off the south coast, where pelagic fish are more abundant. We investigated (1) pelagic fish density using data from a hydro-acoustic survey, (2) gannet diet (stomach content analyses, fatty acid and stable isotope analyses), (3) gannet foraging effort and at-sea feeding areas (nest attendance patterns, GPS-tracking and blood haematocrit), (4) chick growth rates, and (5) adult body condition (morphometric measurements and breast muscle thickness). Our data confirmed contrasting prey availability between colonies, although pelagic fish were more abundant on the west coast than in previous years. Gannets exhibit dietary plasticity, feeding on pelagic fish and trawler discards, but favour natural prey when available. Stomach content samples showed that gannets from both islands mainly ate natural prey in 2009, but there were differences in their stable isotope and fatty acid signatures, supporting evidence of long-term diet differences. Nevertheless, chick growth rates and adult body condition were similar at both colonies, which was surprising for breeding adults from the west coast colony that had been feeding extensively on energy-poor fishery waste for several years. Breeding gannets' behavioural flexibility seems to have succeeded in maintaining body condition. However, this might have long-term costs, as adult survival at Malgas Island has decreased in recent years. Population decreases at this colony are exacerbated by low juvenile survival and perhaps differential recruitment to Bird Island. Higher foraging effort by adult breeding on the large colony of Bird Island compared to birds from the west coast, despite greater pelagic fish abundance on the south coast, probably suggests a greater intra-specific competition there. Monitoring of population trends, population health indices and foraging behaviour, as well as prey availability is necessary to better understand the mechanisms underlying the population trends. © 2012 Elsevier B.V..
Bell J.D.,Fisheries |
Ganachaud A.,Institute Of Recherche Pour Le Developpement |
Ganachaud A.,CNRS Geophysical Research and Oceanographic Laboratory |
Gehrke P.C.,SMEC Australia Pty Ltd |
And 13 more authors.
Nature Climate Change | Year: 2013
Pacific Island countries have an extraordinary dependence on fisheries and aquaculture. Maintaining the benefits from the sector is a difficult task, now made more complex by climate change. Here we report how changes to the atmosphere-ocean are likely to affect the food webs, habitats and stocks underpinning fisheries and aquaculture across the region. We found winners and losers - tuna are expected to be more abundant in the east and freshwater aquaculture and fisheries are likely to be more productive. Conversely, coral reef fisheries could decrease by 20% by 2050 and coastal aquaculture may be less efficient. We demonstrate how the economic and social implications can be addressed within the sector - tuna and freshwater aquaculture can help support growing populations as coral reefs, coastal fisheries and mariculture decline. © 2013 Macmillan Publishers Limited. All rights reserved.
Bell J.D.,Fisheries |
Bell J.D.,Betty and Gordon Moore Center for Science and Oceans |
Bell J.D.,University of Wollongong |
Allain V.,Fisheries |
And 18 more authors.
Marine Policy | Year: 2015
The large tuna resources of the Western and Central Pacific Ocean are delivering great economic benefits to Pacific Island countries and territories (PICTs) through sale of licences to distant water fishing nations and employment in fish processing. However, tuna needs to contribute to Pacific Island societies in another important way-by increasing local access to the fish required for good nutrition to help combat the world's highest levels of diabetes and obesity. Analyses reported here demonstrate that coastal fisheries in 16 of the 22 PICTs will not provide the fish recommended for good nutrition of growing Pacific Island populations, and that by 2020 tuna will need to supply 12% of the fish required by PICTs for food security, increasing to 25% by 2035. In relative terms, the percentages of the region's tuna catch that will be needed in 2020 and 2035 to fill the gap in domestic fish supply are small, i.e., 2.1% and 5.9% of the average present-day industrial catch, respectively. Interventions based on expanding the use of nearshore fish aggregating devices (FADs) to assist small-scale fishers catch tuna, distributing small tuna and bycatch offloaded by industrial fleets at regional ports, and improving access to canned tuna for inland populations, promise to increase access to fish for sustaining the health of the region's growing populations. The actions, research and policies required to implement these interventions effectively, and the investments needed to maintain the stocks underpinning the considerable socio-economic benefits that flow from tuna, are described. © 2014 Elsevier Ltd.
Hobday A.J.,CSIRO |
Bell J.D.,Fisheries |
Bell J.D.,University of Wollongong |
Cook T.R.,University of Cape Town |
And 2 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2015
Fishing in the open ocean often results in unwanted effects on target species, and interactions with non-target species (direct interactions) or influences on the prey or habitat of target and non-target species (indirect interactions). A number of conflicts and trade-offs exist in the harvesting of pelagic species, including (i) maximizing future food production given the depleted state of some stocks; (ii) minimizing bycatch of non-target species, (iii) setting ecosystem allocation rules for non-target top predators, such as seabirds, and (iv) maximizing value and livelihoods for local economies. Climate change can be expected to exacerbate some of these conflicts as the ranges of species and their habitats change over varying geographic, depth and temporal scales. Understanding the distribution of these impacts can be difficult due to the scarcity of observational data on species and ecosystems. Resolving all these conflicts is achievable with current approaches and technologies. Nevertheless, managing fishery production systems to provide fish for food security and conserving biodiversity will be particularly challenging. The complexity added by climate change can be managed with greater use of early warning systems and precautionary management. © 2014.
PubMed | Fisheries, University of Maine, United States and Sustainability Solutions Initiative and.
Type: Journal Article | Journal: Proceedings of the National Academy of Sciences of the United States of America | Year: 2014
Vernal pools are far more important for providing ecosystem services than one would predict based on their small size. However, prevailing resource-management strategies are not effectively conserving pools and other small natural features on private lands. Solutions are complicated by tensions between private property and societal rights, uncertainties over resource location and function, diverse stakeholders, and fragmented regulatory authority. The development and testing of new conservation approaches that link scientific knowledge, stakeholder decision-making, and conservation outcomes are important responses to this conservation dilemma. Drawing from a 15-y history of vernal pool conservation efforts in Maine, we describe the coevolution of pool conservation and research approaches, focusing on how research-based knowledge was produced and used in support of management decisions. As management shifted from reactive, top-down approaches to proactive and flexible approaches, research shifted from an ecology-focused program to an interdisciplinary program based on social-ecological systems. The most effective strategies for linking scientific knowledge with action changed as the decision-makers, knowledge needs, and context for vernal pool management advanced. Interactions among stakeholders increased the extent to which knowledge was coproduced and shifted the objective of stakeholder engagement from outreach to research collaboration and development of innovative conservation approaches. New conservation strategies were possible because of the flexible, solutions-oriented collaborations and trust between scientists and decision-makers (fostered over 15 y) and interdisciplinary, engaged research. Solutions to the dilemma of conserving small natural features on private lands, and analogous sustainability science challenges, will benefit from repeated negotiations of the science-policy boundary.
PubMed | Anglia, Australian National University, Florida Institute of Technology, University of Washington and 14 more.
Type: Journal Article | Journal: Marine pollution bulletin | Year: 2014
Over 1.3 billion people live on tropical coasts, primarily in developing countries. Many depend on adjacent coastal seas for food, and livelihoods. We show how trends in demography and in several local and global anthropogenic stressors are progressively degrading capacity of coastal waters to sustain these people. Far more effective approaches to environmental management are needed if the loss in provision of ecosystem goods and services is to be stemmed. We propose expanded use of marine spatial planning as a framework for more effective, pragmatic management based on ocean zones to accommodate conflicting uses. This would force the holistic, regional-scale reconciliation of food security, livelihoods, and conservation that is needed. Transforming how countries manage coastal resources will require major change in policy and politics, implemented with sufficient flexibility to accommodate societal variations. Achieving this change is a major challenge - one that affects the lives of one fifth of humanity.
Travnicek P.,Food Republic |
Journal of Food Processing and Preservation | Year: 2016
Honey is a solution with high viscosity and most types of honey exhibit Newtonian behavior. However, some types show non-Newtonian features (thixotropy or dilatancy), which exerts influence on processing of the honey. The aim of this study was to evaluate the rheological properties of honey from Eucalyptus spp. The investigated samples of eucalypt honey originating from Italy or Australia were analyzed by the following methods: melissopalynological analysis, color on the Pfund scale, optical activity, water content and electrolytic conductivity. Rheological tests were carried out on a highly accurate device. The dependence of apparent viscosity on temperature and time was measured, and hysteresis loop tests were run. The dependence of shear rate on shear stress was described in accordance with the Herschel-Bulkley mathematical model. The rheological tests revealed the following: all samples exhibited non-Newtonian behavior and all were determined as thixotropic fluids. These results are discussed in relation to previous findings on the dilatant behavior of eucalypt honey. Practical Applications: Knowledge of rheological properties of foodstuff is important for handling, processing and storing. The description of flow properties can indirectly offer information about the structure of the tested liquid. Most honeys behave as Newtonian fluids. However, there are exceptions such as heather or manuka honey. Eucalypt honey is also among these exceptions. Studies dealing with rheological properties of eucalypt honey are more than 60-years old. This study focused on rheological behavior of this type of honey and revised current knowledge. © 2016 Wiley Periodicals, Inc.
Hashimoto Y.,Tokyo University of Agriculture and Technology |
Takamoto A.,Tokyo University of Agriculture and Technology |
Kikkawa R.,Mie University |
Murakami K.,Fisheries |
Yamaguchi N.,Japan National Institute for Agro - Environmental Sciences
Environmental Science and Technology | Year: 2014
Little is known about how the solubility and chemical speciation of phosphorus (P) in poultry litters are altered during the composting period. This study investigated the quantitative and qualitative changes in organic P (Po) and inorganic P (Pi) compositions in poultry litters during the seven-day composting period using sequential extraction in combination with P K-edge X-ray absorption near-edge structure (XANES) and solution 31P nuclear magnetic resonance (NMR) spectroscopy. The result of sequential extraction illustrated that the significant decrease of H2O-P by 55% in poultry litters occurred concomitantly with the increase of HCl-Pi and HCl-Po during the composting period (p < 0.05). X-ray diffraction results for poultry litter samples showed three distinct peaks indicative of hydroxyapatite. Phosphorus K-edge XANES confirmed the increase of hydroxyapatite during the composting period, corresponding to the increase of HCl-Pi determined by the sequential extraction. The NaOH-EDTA extraction for solution 31P NMR revealed that myo-inositol hexakisphosphate (IHP) constituted about 80% of phosphate monoesters and was increased from 16 to 28% in the poultry litter during the composting period. The combined applications of chemical extraction and molecular-spectroscopic techniques determined that water-soluble P in poultry litter was transformed into less soluble phases, primarily hydroxyapatite and IHP, during the composting period. © 2014 American Chemical Society.
Ford J.R.,University of Melbourne |
Proceedings of the Royal Society of Victoria | Year: 2016
Victoria has lost vast areas (>95%) of native flat oyster (Ostrea angasi, Sowerby 1871) and blue mussel (Mytilus edulis galloprovinicialis, Lamarck 1819) reefs from estuarine and coastal waters since European settlement. We document the decline of these reefs by examining indigenous use of shellfish, the decimation of oyster reefs by dredge fishing in early colonial days (1840s-1860s) and later removal of mussel reefs by the mussel and scallop dredging industry (1960s?1990s). Review of current scientific information reveals no notable areas of continuous oyster reef in Victoria and we consider this habitat to be functionally extinct. While the large-scale removal and destructive fishing practices that drove the rapid declines have not occurred since the mid-1990s, a natural recovery has not occurred. Recovery has likely been hampered historically by a host of factors, including water quality and sedimentation, lack of shell substrate for settlement, chemical pollution impacts, disease of native flat oysters (Bonamia), and more recently introduced species that compete with or prey on shellfish. However, research in the United States has demonstrated that, by strategic selection of appropriate sites and provision of suitable settlement substrates, outplanting of aquaculture-reared oysters and mussels can re-establish shellfish reefs. While a long-Term sustained and structured approach is required, there is potential to re-establish shellfish reefs as a functioning ecological community in Victoria's coastal environment.
PubMed | Fisheries, Agri Science Queensland, University of Queensland and CSIRO
Type: Journal Article | Journal: Journal of fish biology | Year: 2016
Sustainable exploitation of fisheries populations is challenging to achieve when the size of the population prior to exploitation and the actual numbers removed over time and across fishing zones are not clearly known. Quantitative fisheries modeling is able to address this problem, but accurate and reliable model outcomes depend on high quality input data. Much of this information is obtained through the operation of the fishery under consideration, but while this seems appropriate, biases may occur. For example, poorly quantified changes in fishing methods that increase catch rates can erroneously suggest that the overall population size is increasing. Hence, the incorporation of estimates of abundance derived from independent data sources is preferable. We review and evaluate a fisheries-independent method of indexing population size; inferring adult abundance from estimates of the genetic effective size of a population (N