Accumulated marine pollution and fishery dynamics

We analyze the possible impacts of pollution on a fishery by means of a dynamical systems theory approach. The proposed model presupposes that activities stimulating economic growth also cause higher emissions that remediate or accumulate in the oceans. The density of pollution is assumed to affect the fishery negatively by reducing biological growth potential and decreasing marginal willingness to pay for the fish in the market. Additionally, economic growth increases the general income and may also increase the demand for fish. We show that the modelling framework permits a unique stable equilibrium state in the regime of moderate values of the emission-remediation ratio. We also investigate how the ecological and market impacts alter both the steady state and dynamics of an open access fishery.     

A bioeconomic model of a fishery with saturated catch and variable price: Stabilizing effect of marine reserves on fishery dynamics

In this paper, we study a mathematical bio-economic model of a fishery with varying price. The three dimensional model describes the time evolution of the resource, the fishing effort and the price. The model is original because it considers a nonlinear harvesting function assumed to depend upon stock size and fishing effort with a saturation effect with respect to the resource as well as a price equation depending on demand and supply which is in addition proportional to price. Assuming that the price varies at a fast time scale, we are able to use ”aggregation of variables methods” in order to reduce the model in a two dimensional model at a slow time scale. This aggregated (reduced) model is analyzed. Several numerical simulations of the model are performed to substantiate our analytical findings. The existence of nonlinear harvesting makes the dynamics of the model more complicated, including multiple equilibria, bi-stability and limit cycle. Such large amplitude cycle variations are not desirable because they generate periods of overfishing at periods of very low activity. We then study the effects of marine reserves on the dynamics of the fishery, showing that for an adequate number of small reserves, limit cycle oscillations are switched off.     

Genetics and marine pollution

The development of cytogenetic methods applied to cells and tissues of marine invertebrates has been hampered by (1) a lack of in vitro cell lines, (2) inadequate karyotypic information (partly as a result of too few workers chasing too many organisms), and (3) the failure of their chromosomes to band satisfactorily. Compared to mammalian cytogenetics, our knowledge of marine invertebrates lags behind by several decades. With the current concern about mutagens in the marine environment, and the recognition that the cells of marine species have sensitivities to DNA-damaging agents similar to those of higher organisms, there is a need for methods which can be used (a) in environmental monitoring and (b) to screen potentially harmful substances in the laboratory. In the absence of in vitro cell lines, embryos and larvae have been used to provide a supply of dividing cells for mutation studies, although the advent of molecular methods has now brought with it the means to detect DNA damage without any need for the cells to be in a dividing state. Moreover, the use of FISH (Fluorescence In Situ Hybridisation) now makes it possible to study numerical and structural chromosomal aberrations with far greater accuracy than was previously possible. A new marine genotoxicity assay is described, based on the embryos and larvae of a tube-dwelling polychaete worm (Pomatoceros lamarkii), suitable for both laboratory studies and field monitoring. This new Pomatoceros assay provides, at the same time, a useful model for studying the consequences of adult exposure on the offspring. A novel application of marine cytogenetic research is the study of the evolutionary adaptations of invertebrates living in naturally polluted extreme environments viz. deep sea hydrothermal vents, which are typified by high levels of toxic heavy metals and radionuclides, substances known to inflict damage to DNA. Given these new methodological and conceptual advances, it is predicted that our understanding of the role played by mutation in the marine environment, both in an evolutionary and toxicological context, will increase dramatically over the next decade.     

Changing seascapes, stochastic connectivity, and marine metapopulation dynamics

The probability of dispersal from one habitat patch to another is a key quantity in our efforts to understand and predict the dynamics of natural populations. Unfortunately, an often overlooked property of this potential connectivity is that it may change with time. In the marine realm, transient landscape features, such as mesoscale eddies and alongshore jets, produce potential connectivity that is highly variable in time. We assess the impact of this temporal variability by comparing simulations of nearshore metapopulation dynamics when potential connectivity is constant through time (i.e., when it is deterministic) and when it varies in time (i.e., when it is stochastic). We use mathematical analysis to reach general conclusions and realistic biophysical modeling to determine the actual magnitude of these changes for a specific system: nearshore marine species in the Southern California Bight. We find that in general the temporal variability of potential connectivity affects two important quantities: metapopulation growth rates when the species is rare and equilibrium abundances. Our biophysical models reveal that stochastic outcomes are almost always lower than their deterministic counterparts, sometimes by up to 40%. This has implications for how we use spatial information, such as connectivity, to manage nearshore (and other) systems.     

Effects of market price on the dynamics of a spatial fishery model: Over-exploited fishery/traditional fishery

We present a dynamical model of a spatial fishery describing the time evolution of the fish stock, the fishing effort and the market price of the resource. The market price is fixed by the gap between the supply and the demand. Assuming two time scales, we use “aggregation of variables methods” in order to derive a reduced model governing fish density and fishing effort at a slow time scale. The bifurcation analysis of the reduced model is performed. According to parameters values, three main cases can occur: (i) a stable fishery free equilibrium, (ii) a stable persistent fishery equilibrium and (iii) coexistence of three strictly positive equilibria, two of them being stable separated by a saddle. In this last case, a stable equilibrium corresponds to a traditional fishery with large fish stock, small fishing effort and small market price. The second stable one corresponds to over-exploitation of the resource with small fish stock, large fishing effort and large market price.     

Evolutionary dynamics, epistatic interactions, and biological information

We investigate a definition of biological information that connects population genetics with the tools of information theory by focusing on the distribution of genotypes found in a population. Previous research has treated loci as non-interacting by making specific approximations in the calculation of information-theoretic quantities. We expand earlier mathematical forms to include epistasis, or interactions between mutations at all pairs of loci. Application of our improved measure of biological information to evolution on two-locus, two-allele fitness landscapes demonstrates that mutual information between loci reflects epistatic interaction of mutations. Finally, we consider four-locus, two-allele fitness landscapes with modular structure. As modular interactions are inherently epistatic, we demonstrate that our refined approximation provides insight into the underlying structure of these non-trivial fitness landscapes.     

海洋渔业资源地理信息系统应用的时空问题

利用GIS描述海洋渔业资源时空动态变化。建立渔业资源评估模型和预测模型,是当前渔业现代化的重要趋势之一．在回顾海洋渔业地理信息系统(MFGIS)发展的基础上。分析了其应用实例及不足,重点探讨了MFGIS所面临的时空数据获取与标准、时空数据表达、时空动态尺度和时空统计与分析模型四方面的技术内涵。并讨论了解决途径．     

Genetic diversity and resistance to marine pollution

We tested in the laboratory three pairs of species belonging to three genera and families of marine gastropods, Monodonta turbinata, M. turbiformis (Trochidae), Littorina punctata, L. neritoides (Littorinidae), Cerithium scabridum, C. rupestre (Cerithiidae), for resistance to diverse inorganic (heavy metals and NaC1) and organic (detergents and crude oil) pollutants. Each pair consisted of one narrow-niche species with low genetic diversity and one broad-niche species with higher genetic diversity. Evidence is presented that in all three cases the species with a higher level of genetic diversity was more resistant to all pollutants than its counterpart. These results suggest that fitness is positively correlated with heterozygosity and support the niche-width-variation hypothesis in regard to pollutants. The results also have practical implications for the identification of optimum marine species as genetic monitors of pollution.     

Transmembrane helix structure, dynamics, and interactions: multi-nanosecond molecular dynamics simulations.

To probe the fundamentals of membrane/protein interactions, all-atom multi-nanosecond molecular dynamics simulations were conducted on a single transmembrane poly(32)alanine helix in a fully solvated dimyristoyphosphatidylcholine (DMPC) bilayer. The central 12 residues, which interact only with the lipid hydrocarbon chains, maintained a very stable helical structure. Helical regions extended beyond these central 12 residues, but interactions with the lipid fatty-acyl ester linkages, the lipid headgroups, and water molecules made the helix less stable in this region. The C and N termini, exposed largely to water, existed as random coils. As a whole, the helix tilted substantially, from perpendicular to the bilayer plane (0 degree) to a 30 degrees tilt. The helix experienced a bend at its middle, and the two halves of the helix at times assumed substantially different tilts. Frequent hydrogen bonding, of up to 0.7 ns in duration, occurred between peptide and lipid molecules. This resulted in correlated translational diffusion between the helix and a few lipid molecules. Because of the large variation in lipid conformation, the lipid environment of the peptide was not well defined in terms of "annular" lipids and on average consisted of 18 lipid molecules. When compared with a "neat" bilayer without peptide, no significant difference was seen in the bilayer thickness, lipid conformations or diffusion, or headgroup orientation. However, the lipid hydrocarbon chain order parameters showed a significant decrease in order, especially in those methylene groups closest to the headgroup.     

Multi-year dynamics of fine-scale marine cyanobacterial populations are more strongly explained by phage interactions than abiotic,bottom-up factors

Currently defined ecotypes in marine cyanobacteria Prochlorococcus and Synechococcus likely contain subpopulations that themselves are ecologically distinct. We developed and applied high-throughput sequencing for the 16S-23S rRNA internally transcribed spacer (ITS) to examine ecotype and fine-scale genotypic community dynamics for monthly surface water samples spanning 5 years at the San Pedro Ocean Time-series site. Ecotype-level structure displayed regular seasonal patterns including succession, consistent with strong forcing by seasonally varying abiotic parameters (e.g. temperature, nutrients, light). We identified tens to thousands of amplicon sequence variants (ASVs) within ecotypes, many of which exhibited distinct patterns over time, suggesting ecologically distinct populations within ecotypes. Community structure within some ecotypes exhibited regular, seasonal patterns, but not for others, indicating other more irregular processes such as phage interactions are important. Network analysis including T4-like phage genotypic data revealed distinct viral variants correlated with different groups of cyanobacterial ASVs including time-lagged predator–prey relationships. Variation partitioning analysis indicated that phage community structure more strongly explains cyanobacterial community structure at the ASV level than the abiotic environmental factors. These results support a hierarchical model whereby abiotic environmental factors more strongly shape niche partitioning at the broader ecotype level while phage interactions are more important in shaping community structure of fine-scale variants within ecotypes.     

Environmental assessment of the Peruvian industrial hake fishery with LCA

Purpose

The Peruvian hake (Merluccius gayi peruanus) stock has been in a delicate state in the last decades due to overexploitation combined with adverse climatic events. The stock is showing certain signs of recovery since 2012. This work analyses the environmental impacts of current fleet operations and its likely trend.

Methods

The fleet was divided into coherent segments, per holding capacity and engine power. The validity of both segmentations, as well as the presence of an effect of economies of scale driving fuel use intensity (FUI), was tested. Life cycle assessment was used to calculate environmental impacts, per individual sampled vessel and per segment, complemented with indicators of energy efficiency and biotic resource depletion.

Results and discussion

The fleet is highly fuel-efficient (120 kg fuel per tonne fish) when compared with other reported values, despite a large overcapacity that increases the impact of the construction and maintenance phases. Significant inter-annual FUI variations were observed (80.0 kg t^?1 in 2008 to 210.3 kg t^?1 in 2006), but no clear trend. Neither significant differences in FUI among fleet segments nor a clear effect of economies of scale were found (but FUI analysis was based on a small sample of 32 values for nine vessels, two of which had data for a single year). Only the largest vessels, featuring 242 m³ holding capacity and 850 hp engine power, were found to have lower FUI than any of the other vessels, but no statistical test could be applied to validate this difference. Differences in environmental impacts of individual vessels are mostly dominated by their relative FUI. Fuel use and, to a lower extent, maintenance are the main sources of environmental impacts. The most contributing impacts to ReCiPe single score are climate change, human toxicity and fossil depletion. The fishery’s impacts on the biotic natural resource were orders of magnitude higher than many other global hake stocks, due to overexploitation.

Conclusions

The environmental impacts of the national hake fleet are relatively low during the study period, despite an overcapacity of the fleet. With the perspective of expanding its operations and obtaining better yields on the eventuality that the stock fully recovers, these impacts should decrease. More research based on additional FUI data is necessary to effectively compare the performance of these vessels with larger ones (featuring >180 m³ and >500 hp, of which nine existed in 2016) before possibly recommending their preferential use.

     

An approach to analysis of colonization dynamics in community functioning of protozoa for bioassessment of marine pollution

Biological trait analysis is a powerful tool to summarize the spatial/temporal patterns of community functioning and ecosystem process at taxon-free resolutions. To identify the optimal colonization period with high homogeneity in functional patterns of protozoa for bioassessment, 1-month baseline colonization survey was conducted in coastal waters of the Yellow Sea. A fuzzy-coding functional trait system was used to summarize the functional structure of protozoan communities during the colonization process. The functional patterns showed a low homogeneity during the early stage (3–7 days), followed by a stable stage (10–14 days) with high homogeneity, and the last stage (21–28 days) with high heterogeneity. The functional richness showed a low variability, while the functional evenness and divergence generally showed a decreasing trend during the whole colonization process. Furthermore, the functional dispersion and RaoQ indices generally leveled off only during the stable stage. These results suggest that it is necessary to determine the optimal exposure time period with high homogeneity of community functioning for bioassessment using protozoan colonization in marine ecosystems.     

Biotic interactions of marine algae

Marine algae encompass lineages that diverged about one billion years ago. Recent results suggest that they feature natural immunity traits that are conserved, as well as others that appear to be phylum- or environment-specific. In particular, marine plants resemble terrestrial plants and animals in their basic mechanisms for pathogen recognition and signaling, suggesting that these essential cell functions arose in the sea. Specific traits are based on the synthesis of unique secondary defense metabolites, often making use of the variety of halides found in the sea.     

Soil pollution through industrial effluent and its management

During the survey of sewer water/industrial effluent composition, we identified a site at Sonepat that had turned barren due to excessive irrigation with cycle industry effluent. To study the ameliorative effect of farmyard manure, the bulk surface soil sample was brought from the site. Soil was amended with five levels of farmyard manure (0, 0.25, 0.5, 1.0, and 2.0% on a soil weight basis), and carrot, fenugreek, spinach, and wheat crops were grown as test crops in a screen house. The deleterious effect of excessive heavy metals, particularly Ni, on the yield of all the crops was reduced with the application of 2% farmyard manure. The Ni content was highest in carrot, followed by spinach, fenugreek, and wheat. With the application of 2% farmyard manure, Ni content was reduced from 434 to 267 mg/kg in carrot, 167 to 100 mg/kg in fenugreek, 300 to 166 mg/kg in spinach, and 65 to 42 mg/kg in wheat grain.     

A framework for assessing the biodiversity and fishery aspects of marine reserves

1.  Resource management agencies are often charged with managing natural resources for economic and social goals, while also protecting and conserving biodiversity and ecosystem function. However, this may not always be possible. Ecosystem-based management is frequently suggested as a way to achieve multiple objectives in resource management and requires that trade-offs among conflicting objectives be identified and an effective means to utilize these trade-offs developed.
2.  We examine the relationship between area and species richness in a diverse assemblage of fishes along the US West Coast and then use parameters from this relationship as input for a model that considers trade-offs between fisheries yield and the number of species protected by different management strategies.
3.  The species–area relationship ( S  =  cA ^z ) for fishes along the US Pacific coast is well described by the relationship S  =   16·18 A ^0·226.
4.  There are nearly linear trade-offs between diversity and yield when fishing effort is low. However, the trade-offs become nonlinear as fishing effort increases and imposing MPAs increases both the conservation and fisheries value of the system when the system is overfished.
5.   Synthesis and applications . Solving conflicts between fisheries and conservation requires attention as to how conservation benefits accrue as fishing effort is reduced. However, scientists often lack quantitative information about the trade-offs inherent in human activities such as fisheries. The approach we develop here can begin to help frame the questions to be posed and evaluate the likely consequences of different management options.     

The control of radioactive pollution in a north sea oyster fishery

Summary 1. The radiological situation in the Blackwater estuary is reviewed.2. Some data are produced to contrast the behaviour of particulate and soluble nuclides in this estuarine environment and it is demonstrated that⁶⁵Zn,⁶⁰Co and⁵⁵Fe probably reach the oysters on fine silt particles.3. The conclusion of the pre-operational assessment is confirmed, that oysters are the critical material and⁶⁵Zn is the critical radionuclide.4. At present, oysters are the only material in which measurable concentrations of activity exist throughout the estuary.5. The maximum dose-rates experienced by exceptional oyster consumers are less than 0.2% of the I.C.R.P. permissible Dose Limits for members of the public.6. A system is developed to relate oyster contamination, and consequently discharge rate of radioactivity, to any distance from the power station outfall.

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Die Kontrolle radioaktiver Verunreinigung in einer Austernfischerei der Nordsee

Kurzfassung Im Ästuar des Flusses Blackwater wird eine kommerzielle Austernfischerei betrieben. In die Flußmündung werden in niedrigen Konzentrationen radioaktive Abwässer von der Bradwell Nuclear Power Station geleitet. Die Situation bezüglich der radioaktiven Verunreinigung des Flusses wird dargestellt und das Überwachungssystem des Ministry of Agriculture, Fisheries and Food beschrieben, wobei darauf hingewiesen wird, daß die Stärke der Radioaktivität auf einer kommerziell genutzten Austernbank ausreichend gut kontrolliert werden kann. Das kritische Radionuklid ist⁶⁵Zn, das im Austernfleisch enthalten ist. Anhand der Werte der spezifischen Aktivität von⁶⁵Zn,⁶⁰Co,⁵⁵Fe und¹³⁷Cs von Austern, die in unmittelbarer Nähe des Abwassereinflusses lebten, wird gezeigt, daß im ungünstigsten Falle der Austernkonsument 0,2% der von der I.C.R.P. zugelassenen Menge aufnimmt.