2015-10-28

Spatio-temporal Bayesian network models with latent variables for revealing trophic dynamics and functional networks in fisheries ecology

Trifonova N, Kenny A, Maxwell D, Duplisea D, Fernandes J, Tucker A. Spatio-temporal Bayesian network models with latent variables for revealing trophic dynamics and functional networks in fisheries ecology. Ecological Informatics [Internet]. 2015 ;30:142 - 158. Available from: http://www.sciencedirect.com/science/article/pii/S1574954115001648
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Ecosystems consist of complex dynamic interactions among species and the environment, the understanding of which has implications for predicting the environmental response to changes in climate and biodiversity. However, with the recent adoption of more explorative tools, like Bayesian networks, in predictive ecology, few assumptions can be made about the data and complex, spatially varying interactions can be recovered from collected field data. In this study, we compare Bayesian network modelling approaches accounting for latent effects to reveal species dynamics for 7 geographically and temporally varied areas within the North Sea. We also apply structure learning techniques to identify functional relationships such as prey–predator between trophic groups of species that vary across space and time. We examine if the use of a general hidden variable can reflect overall changes in the trophic dynamics of each spatial system and whether the inclusion of a specific hidden variable can model unmeasured group of species. The general hidden variable appears to capture changes in the variance of different groups of species biomass. Models that include both general and specific hidden variables resulted in identifying similarity with the underlying food web dynamics and modelling spatial unmeasured effect. We predict the biomass of the trophic groups and find that predictive accuracy varies with the models' features and across the different spatial areas thus proposing a model that allows for spatial autocorrelation and two hidden variables. Our proposed model was able to produce novel insights on this ecosystem's dynamics and ecological interactions mainly because we account for the heterogeneous nature of the driving factors within each area and their changes over time. Our findings demonstrate that accounting for additional sources of variation, by combining structure learning from data and experts' knowledge in the model architecture, has the potential for gaining deeper insights into the structure and stability of ecosystems. Finally, we were able to discover meaningful functional networks that were spatially and temporally differentiated with the particular mechanisms varying from trophic associations through interactions with climate and commercial fisheries.

Assessing harbour porpoise populations in south-west Wales, data issues and implications for conservation and management

Oakley JA, Jenkins RE, Thomas T, Williams AT, Phillips MR. Assessing harbour porpoise populations in south-west Wales, data issues and implications for conservation and management. Ocean & Coastal Management [Internet]. 2016 ;119:45 - 57. Available from: http://www.sciencedirect.com/science/article/pii/S0964569115300284
Freely available?: 
No
Summary available?: 
No
Type: Journal Article

The UK Government was recently criticised for failing to fulfil its obligations under the Habitats Directive in respect of designating protected areas for Harbour Porpoise Phocoena phocoena. At the centre of the discussion lay the stringent nature of the qualifying criteria for site selection. Concurrently, there is a growing support for marine renewable energy technologies; however the planning process is often hampered by inadequate marine data to enable appropriate siting or mitigation against potential ecological impacts. The Bristol Channel region's physical environment is a suitable source for the generation of marine renewable energy, and the world's first tidal lagoon will be sited in Swansea Bay. A 10 year dataset was collected, analysed and compared against the qualifying criteria for a Special Area of Conservation (SAC). Results revealed that a resident population of porpoise existed and density values of 0.58 hp km2 were comparable with other UK regions. While an insignificant calf adult ratio of 1:13 was recorded, breeding and nursery areas were identified. Analysis highlighted a number of hotspots of porpoise activity, suggesting that these areas are critical habitats, particularly for feeding and foraging. Such information will enable future marine renewable energy developers to select the most appropriate sites. It is argued that existing SAC qualifying criteria prevents recognition of critical habitats for the harbour porpoise and a case is made for an eastward extension of a proposed harbour SAC to include Swansea Bay and the south Gower coast. This paper demonstrates that cetacean data is sparse and even though this study has filled important knowledge gaps, there is still a need for further research. This research would enable both developers and planners to adequately and appropriately consider future marine renewable energy projects.

The problems and resolution approaches to land management in the coastal and maritime zones of Turkey

Baser V, Biyik C. The problems and resolution approaches to land management in the coastal and maritime zones of Turkey. Ocean & Coastal Management [Internet]. 2016 ;119:30 - 37. Available from: http://www.sciencedirect.com/science/article/pii/S0964569115300351
Freely available?: 
No
Summary available?: 
No
Type: Journal Article

Today, like in terrestrial zones, the determination and registration of tenure in coastal and maritime zones appear to be mandatory not only from legal, social and economic perspective but also for sustainable environmental administration. In this context, there is a need to redefine and reconstruct these zones. In this study, the institutions and corporations operating in coastal and maritime zones in Turkey and current laws were established and a matrix was formed between the operations and the institutions operating in coastal and maritime zones to evaluate the current structure as a whole. Furthermore, with the objective of determining the problems seen in coastal and maritime zones, some survey and interview studies were conducted concerning the institutions and corporations operating in this field and the current situation was displayed. As a consequence of the study, it was found that the current structures in coastal and maritime zones were not adequate in terms of legal, institutional and technical points. The need for an integrated coastal and maritime zone administration was stated and some suggestions with regard to land management were put forward by developing new approaches.

Service vessel activity in the U.S. Gulf of Mexico in support of the oil and gas industry using AIS data, 2009–2010

Kaiser MJ. Service vessel activity in the U.S. Gulf of Mexico in support of the oil and gas industry using AIS data, 2009–2010. Marine Policy [Internet]. 2016 ;63:61 - 80. Available from: http://www.sciencedirect.com/science/article/pii/S0308597X15002833
Freely available?: 
No
Summary available?: 
No
Type: Journal Article

Offshore exploration and production in the U.S. Gulf of Mexico is supported by a large number of service vessels characterized by complex logistical patterns and demand points distributed across an expansive geographic area. No quantitative data on the spatial and temporal distributions of service vessel activity in the region is available due to the size, complexity and dynamics of the network. The purpose of this paper is to apply Automatic Identification System position data to quantify service vessel activity in the U.S. Gulf of Mexico from 2009 to 2010. A total of 1.1 million vessel arrivals and departures were recorded in 2009–2010, and in 2010, the number of vessel events increased by 40% due in part to the Macondo oil spill and cleanup response. Port-to-port movements comprise the majority of events and about 30% of activity relates to movements offshore. Port Fourchon, Venice, New Orleans, Sabine-Neches, and Lake Charles were the most active ports during the period. A detailed breakdown of vessel counts and the limitations of the analysis are outlined.

Using kernel density estimation to explore habitat use by seabirds at a marine renewable wave energy test facility

Lees KJ, Guerin AJ, Masden EA. Using kernel density estimation to explore habitat use by seabirds at a marine renewable wave energy test facility. Marine Policy [Internet]. 2016 ;63:35 - 44. Available from: http://www.sciencedirect.com/science/article/pii/S0308597X15002845
Freely available?: 
No
Summary available?: 
No
Type: Journal Article

If Scottish Government targets are met, the equivalent of 100% of Scotland's electricity demand will be generated from renewable sources by 2020. There are several possible risks posed to seabirds from marine renewable energy installations (MREIs) and many knowledge gaps still exist around the extent to which seabird habitats can overlap with MREIs. In this study, underlying seasonal and interannual variation in seabird distributions was investigated using kernel density estimation (KDE) to identify areas of core habitat use. This allowed the potential interactions between seabirds and a wave energy converter (WEC) to be assessed. The distributions of four seabird species were compared between seasons, years, and in the presence and absence of WECs. Although substantial interannual variation existed in baseline years prior to WEC deployment, the KDEs for all four species analysed were closer to the mooring points in the presence of a WEC in at least one season. The KDEs for all four species also increased in area in at least one season in the presence of a WEC. The KDEs of the northern fulmar and great skua overlapped the mooring points during spring in the presence of a device. The density of observations close to the mooring points increased for great skua, northern gannet, and northern fulmar during summer in the presence of a device. These results suggest that none of the four species analysed have shown avoidance or an extreme change in distribution as a result of the presence of a WEC. The continued monitoring of seabirds during WEC deployments is necessary to provide further data on how distributions may change in response to the presence of WECs.

Sand temperatures for nesting sea turtles in the Caribbean: Implications for hatchling sex ratios in the face of climate change

Laloë J-O, Esteban N, Berkel J, Hays GC. Sand temperatures for nesting sea turtles in the Caribbean: Implications for hatchling sex ratios in the face of climate change. Journal of Experimental Marine Biology and Ecology [Internet]. 2016 ;474:92 - 99. Available from: http://www.sciencedirect.com/science/article/pii/S0022098115300289
Freely available?: 
No
Summary available?: 
No
Type: Journal Article

A 200-year time series of incubation temperatures and primary sex ratios for green (Chelonia mydas), hawksbill (Eretmochelys imbricata) and leatherback (Dermochelys coriacea) sea turtles nesting in St. Eustatius (North East Caribbean) was created by combining sand temperature measurements with historical and current environmental data and climate projections. Rainfall and spring tides were important because they cooled the sand and lowered incubation temperatures. Mean annual sand temperatures are currently 31.0 °C (SD = 1.6) at the nesting beach but show seasonality, with lower temperatures (29.1–29.6 °C) during January–March and warmer temperatures (31.9–33.3 °C) in June–August. Results suggest that all three species have had female-biased hatchling production for the past decades with less than 15.5%, 36.0%, and 23.7% males produced every year for greens, hawksbills and leatherbacks respectively since the late nineteenth century. Global warming will exacerbate this female-skew. For example, projections indicate that only 2.4% of green turtle hatchlings will be males by 2030, 1.0% by 2060, and 0.4% by 2090. On the other hand, future changes to nesting phenology have the potential to mitigate the extent of feminisation. In the absence of such phenological changes, management strategies to artificially lower incubation temperatures by shading nests or relocating nest clutches to deeper depths may be the only way to prevent the localised extinction of these turtle populations.

Implications of new economic policy instruments for tuna management in the Western and Central Pacific

Yeeting AD, Bush SR, Ram-Bidesi V, Bailey M. Implications of new economic policy instruments for tuna management in the Western and Central Pacific. Marine Policy [Internet]. 2016 ;63:45 - 52. Available from: http://www.sciencedirect.com/science/article/pii/S0308597X15002870
Freely available?: 
No
Summary available?: 
No
Type: Journal Article

Tuna management in the Western and Central Pacific is complicated by the conflicting interests of countries and agents exploiting tuna resources in the region. Historically, regulatory attempts by Pacific Island Countries to control fishing effort within their Exclusive Economic Zones (EEZs) have met with limited success. The introduction of new economic policy instruments by the Parties to the Nauru Agreement (PNA), such as the Vessel Day Scheme (VDS) and Marine Stewardship Council (MSC) certification, has supported and complemented existing conservation and management measures. By bringing in new incentives for the PNA states, greater control over fishing effort and the formulation of perceptibly new sustainable fishing practices have emerged. Using a new institutional economic framework, this paper analyses the shift from regulatory policy to new economic policy instruments through the lens of New Institutional Economics. The results show how the adoption of the VDS and MSC certification program has brought new changes and improvements to tuna negotiations, to agreements, and to outcomes amongst parties. Investing in these new instruments has elucidated ways in which new economic institutions strengthen de jure political control over transboundary fish resources and fishing fleets.

Canada at a crossroad: The imperative for realigning ocean policy with ocean science

Bailey M, Favaro B, Otto SP, Charles A, Devillers R, Metaxas A, Tyedmers P, Ban NC, Mason T, Hoover C, et al. Canada at a crossroad: The imperative for realigning ocean policy with ocean science. Marine Policy [Internet]. 2016 ;63:53 - 60. Available from: http://www.sciencedirect.com/science/article/pii/S0308597X15002869
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Canada's ocean ecosystem health and functioning is critical to sustaining a strong maritime economy and resilient coastal communities. Yet despite the importance of Canada's oceans and coasts, federal ocean policy and management have diverged substantially from marine science in the past decade. In this paper, key areas where this is apparent are reviewed: failure to fully implement the Oceans Act, alterations to habitat protections historically afforded under Canada's Fisheries Act, and lack of federal leadership on marine species at risk. Additionally, the capacity of the federal government to conduct and communicate ocean science has been eroded of late, and this situation poses a significant threat to current and future oceans public policy. On the eve of a federal election, these disconcerting threats are described and a set of recommendations to address them is developed. These trends are analyzed and summarized so that Canadians understand ongoing changes to the health of Canada's oceans and the role that their elected officials can play in addressing or ignoring them. Additionally, we urge the incoming Canadian government, regardless of political persuasion, to consider the changes we have documented and commit to aligning federal ocean policy with ocean science to ensure the health of Canada's oceans and ocean dependent communities.

Global alteration of ocean ecosystem functioning due to increasing human CO2 emissions

Nagelkerken I, Connell SD. Global alteration of ocean ecosystem functioning due to increasing human CO2 emissions. Proceedings of the National Academy of Sciences [Internet]. 2015 . Available from: http://www.pnas.org/content/112/43/13272.abstract.html
Freely available?: 
No
Summary available?: 
No
Type: Journal Article

Rising anthropogenic CO2 emissions are anticipated to drive change to ocean ecosystems, but a conceptualization of biological change derived from quantitative analyses is lacking. Derived from multiple ecosystems and latitudes, our metaanalysis of 632 published experiments quantified the direction and magnitude of ecological change resulting from ocean acidification and warming to conceptualize broadly based change. Primary production by temperate noncalcifying plankton increases with elevated temperature and CO2, whereas tropical plankton decreases productivity because of acidification. Temperature increases consumption by and metabolic rates of herbivores, but this response does not translate into greater secondary production, which instead decreases with acidification in calcifying and noncalcifying species. This effect creates a mismatch with carnivores whose metabolic and foraging costs increase with temperature. Species diversity and abundances of tropical as well as temperate species decline with acidification, with shifts favoring novel community compositions dominated by noncalcifiers and microorganisms. Both warming and acidification instigate reduced calcification in tropical and temperate reef-building species. Acidification leads to a decline in dimethylsulfide production by ocean plankton, which as a climate gas, contributes to cloud formation and maintenance of the Earth’s heat budget. Analysis of responses in short- and long-term experiments and of studies at natural CO2 vents reveals little evidence of acclimation to acidification or temperature changes, except for microbes. This conceptualization of change across whole communities and their trophic linkages forecast a reduction in diversity and abundances of various key species that underpin current functioning of marine ecosystems.

An evaluation of implementing long-term MSY in ecosystem-based fisheries management: Incorporating trophic interaction, bycatch and uncertainty

Zhang C, Chen Y, Ren Y. An evaluation of implementing long-term MSY in ecosystem-based fisheries management: Incorporating trophic interaction, bycatch and uncertainty. Fisheries Research [Internet]. 2016 ;174:179 - 189. Available from: http://www.sciencedirect.com/science/article/pii/S0165783615301041
Freely available?: 
No
Summary available?: 
No
Type: Journal Article

Maximum sustainable yield (MSY), often defined in relation to a single species considered in isolation, has long been considered a cornerstone in fisheries management. It is difficult to expand the concept of MSY for the purpose of ecosystem-based fisheries management (EBFM). Here we consider MSY for a fishery in a multispecies fish community by addressing issues of trophic interaction and bycatch, along with parameter uncertainty. A size-spectrum model, which fully considers trophic interactions within the fish community, was used for simulating various fisheries scenarios including a single species fishery, a multispecies stow-net fishery, and a multispecies trawl fishery. Population biomasses, yields, and ecological indicators were used to assess the dynamics of the fishery and fish community status. The single species fishery with no bycatch resulted in a low impact on non-target stocks, but led to the collapse of the target stock at low fishing mortality rates. The stow-net and trawl fisheries had broader ecosystem impacts, but allowed target stocks to be fished at much higher fishing mortality rates with higher yields. Ecological indicators were related non-linearly to fishing mortality, possibly diminishing their effectiveness as management tools. Background resource carrying capacity was found to be a greater source of uncertainty than reproductive efficiency. This study demonstrates that bycatch mortality can play an important role in trophic interactions likely via predation release and depensation, and thus influence the resilience of fisheries to fishing pressure. The study indicates that the combination of mixed fisheries and multispecies effects lead to complex fish community dynamics that may present additional challenges for fisheries management.

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