104 research outputs found
The Impact of Physical Disturbance and Increased Sand Burial on Clonal Growth and Spatial Colonization of Sporobolus virginicus in a Coastal Dune System
Dune plants are subjected to disturbance and environmental stresses, but little is known about the possible combined
effects of such factors on growth and spatial colonization. We investigated how clones of Sporobolus virginicus, a
widespread dune species, responded to the independent and interactive effects of breakage of rhizomes, breakage
position and burial regime. Horizontal rhizomes were severed at three different internode positions relative to the
apex to span the range of damage by disturbance naturally observed or left intact, and apical portions exposed to two
burial scenarios (ambient vs. increased frequency) for three months in the field. The performance of both parts of
severed rhizomes, the apical portion and the remaining basal portion connected to clone containing four consecutive
ramets, was compared with that of equivalent parts in intact rhizomes. Apical portions severed proximal to the third
internode did not survive and their removal did not enhance branching on their respective basal portions. Severing
the sixth or twelfth internode did not affect survival and rhizome extension of apical portions, but suppressed ramet
production and reduced total biomass and specific shoot length. Their removal enhanced branching and ramet
production on basal portions and changed the original rhizome growth trajectory. However, the gain in number of
ramets in basal portions never compensated for the reduction in ramet number in apical portions. Recurrent burial
increased biomass allocation to root tissues. Burial also stimulated rhizome extension only in intact rhizomes,
indicating that disturbance interacts with, and counteracts, the positive burial effect. These results suggest that
disturbance and recurrent burial in combination reduces the regeneration success and spread capacity of S.
virginucus. Since global change leads to increasingly severe or frequent storms, the impact of disturbance and burial
on clones could be greater in future and possibly prevent colonization of mobile dunes by the species
First evidence of root morphological and architectural variations in young Posidonia oceanica plants colonizing different substrate typologies
Root morphology and root system architecture of young Posidonia oceanica plants established on two
contrasting substrate types, sand and rock, were examined to provide insights into the strategy of
adaptation of seagrasses to their environment. After germination, seedlings were planted on sandy
patches and on rock within the same area, and survived plants were collected five years later for
measurements of the size of the entire root complex and analysis of individual morphological and
architectural root traits. Collected plants exhibited up to nine highly intermingled root systems and
approx. 2.5 m of total root length. Maximum horizontal extension, total biomass and total length of roots
were not significantly affected by substrate. However, on sand roots grew vertically reaching up to 13 cm,
while on rock they extended more horizontally and did not penetrate deeper than 5e7 cm leading to the
formation of a shallow, densely packed root complex. On rock, the number and the length of second order
laterals on an individual root system were reduced and the topological index higher than on
sand (0.8 vs. 0.7) reflecting a more simple (herringbone) branching pattern. Again, root diameter was
greater than on sand. The results suggest that P. oceanica can adjust root traits early during plant
development according to substrate typology to maximize anchorage and substrate exploration efficiency.
This plasticity enables the species to establish and persist also on rocky bottoms which generally
prevent establishment of the majority of seagrasses
New eco-composites based on polyhydroxyalkanoates (PHA) for marine applications
Bio-based polymers have attracted increasing attention over the last two decades, predominantly due to their environmental friendly nature and no dependence on petroleum resources. This type of polymers has got a growing consideration which has been so far focused specifically on starch based products, PLA (Polylactic acid), PHA (Polyhydroxylalkanoates) in particular PHB (Polyhydroxyl butyrate), cellulose derived plastics, etc. The production of these materials is based on renewable agricultural and biomass feedstocks. The degradability of bio-based materials not just in compost but also in different natural environments is an important property for sustainability and reduction of plastic pollution. In this work, blends of PHA and PHB with Posidonia Oceanica fibres were investigated to assess the feasibility of producing materials biodegradable in marine environment, varying the fiber percentage from 10 to 30 wt%. The chemical composition of the Posidonia O. fiber is similar to that of other lignocellulosic materials. It consists mainly of cellulose, hemicellulose, and lignin. Thermal, rheological, mechanical and morphological characterization of the developed PHA/PHB-fibre blends has been conducted in order to investigate the effect of the fibres on their processability and tensile properties.
Biodegradability of the produced composites has been investigated in sea water in view of their use in marine environment
New Bio-Composites Based on Polyhydroxyalkanoates and Posidonia oceanica Fibres for Applications in a Marine Environment
Bio-composites based on polyhydroxyalkanoates (PHAs) and fibres of Posidonia oceanica
(PO) were investigated to assess their processability by extrusion, mechanical properties, and potential
biodegradability in a natural marine environment. PHAs were successfully compounded with PO
fibres up to 20 wt%while, at 30 wt%of fibres, the addition of 10 wt%of polyethylene glycol (PEG 400)
was necessary to improve their processability. Thermal, rheological, mechanical, and morphological
characterizations of the developed composites were conducted and the degradation of composite
films in a natural marine habitat was evaluated in a mesocosm by weight loss measure during an
incubation period of six months. The addition of PO fibres led to an increase in stiffness of the
composites with tensile modulus values about 80% higher for composites with 30 wt % fibre (2.3 GPa)
compared to unfilled material (1.24 GPa). Furthermore, the impact energy markedly increased with
the addition of the PO fibres, from 1.63 (unfilled material) to 3.8 kJ/m2 for the composites with 30 wt %
PO. The rate of degradation was markedly influenced by seawater temperature and significantly
promoted by the presence of PO fibres leading to the total degradation of the film with 30 wt % PO in
less than six months. The obtained results showed that the developed composites can be suitable to
manufacture items usable in marine environments, for example, in natural engineering interventions,
and represent an interesting valorisation of the PO fibrous wastes accumulated in large amounts on
coastal beaches
Biocomposites based on PHBs and natural fibers for commodity applications in different environments: processing, performance in soil, compost and sea water
Composites based on poly(3-hydroxybutyrate) (PHB) and natural fibres such as fibres of Posidonia oceanica (PO), wood
saw dust (WSD) and bran were produced by extrusion in presence of appropriate amounts of plasticizer (Acetyl Tri-n-
Butyl Citrate, ATBC) and filler (calcium carbonate). Thermal, rheological, mechanical and morphological characterizations
of the developed composites were conducted in order to optimize formulations in terms of processability and mechanical
performance. The biodegradability of the optimized composites was investigated under controlled composting conditions in
accordance with standard methods (ASTM D5338-98, ISO 20200-2004) and in soil for the PHB/WSD composites, because
their expected fate is to be treated in composting plants or used for applications in agriculture; in simulated and natural
marine sediments in mesocosms and dune habitat for the PHB/PO composites, because their potential applications are in
marine environment, such as natural engineering interventions (restoration of seagrass habitats). The optimized PHB/WSD
compounds were used for the production of pots for terrestrial plants, PHB/PO compounds for pots and other items usable
in the sea and sand dunes, such as transplanting tools and structures for restoration or protection of coastal habitats, and the
PHB/bran fibres for the production of food contact containers. The results showed that the industrial processing by extrusion
of the composites did not show any difficulty up to 20 wt. % fibres and the presence of the fibres (PO or WSD) facilitated the
disintegration of the PHB matrix and, consequently, accelerated its biodegradation both in compost, soil, sea water and dune.
The PHB/WSD composites resulted no-phytotoxic by using cress (Lepidium sativum L.) germination test, compostable in
accordance with EN 13427:2000, biodegradable in soil at controlled degradation rate. The PHB/PO composites showed a good
controlled biodegradation rate in marine sediments and were suitable to manufacture items usable, for example, in natural
engineering interventions and represent an interesting valorisation of the PO fibrous wastes accumulated in large amounts on
coastal beaches
Nutrient Loading Fosters Seagrass Productivity under Ocean Acidification
The effects of climate change are likely to be dependent on local settings. Nonetheless, the compounded effects of global and regional stressors remain poorly understood. Here, we used CO2vents to assess how the effects of ocean acidification on the seagrass, Posidonia oceanica, and the associated epiphytic community can be modified by enhanced nutrient loading. P. oceanica at ambient and low pH sites was exposed to three nutrient levels for 16 months. The response of P. oceanica to experimental conditions was assessed by combining analyses of gene expression, plant growth, photosynthetic pigments and epiphyte loading. At low pH, nutrient addition fostered plant growth and the synthesis of photosynthetic pigments. Overexpression of nitrogen transporter genes following nutrient additions at low pH suggests enhanced nutrient uptake by the plant. In addition, enhanced nutrient levels reduced the expression of selected antioxidant genes in plants exposed to low pH and increased epiphyte cover at both ambient and low pH. Our results show that the effects of ocean acidification on P. oceanica depend upon local nutrient concentration. More generally, our findings suggest that taking into account local environmental settings will be crucial to advance our understanding of the effects of global stressors on marine systems
Virus contamination and infectivity in beach environment: Focus on sand and stranded material
To assess the exposure of beachgoers to viruses, a study on seawater, sand, and beach-stranded material was carried out, searching for human viruses, fecal indicator organisms, and total fungi. Moreover, for the first time, the genome persistence and infectivity of two model viruses was studied in laboratory-spiked sand and seawater
samples during a one-week experiment. Viral genome was detected in 13.6 % of the environmental samples, but it was not infectious (Human Adenovirus – HAdV, and enterovirus). Norovirus and SARS-CoV-2 were not detected. The most contaminated samples were from sand and close to riverine discharges. In lab-scale experiments,
the infectivity of HAdV5 decreased by ~1.5-Log10 in a week, the one of Human Coronavirus-229E disappeared in <3 h in sand. The genome of both viruses persisted throughout the experiment. Our results confirm viral contamination of the beach and suggest HAdV as an index pathogen for beach monitoring and quantitative risk assessment
Workshop on accounting for fishers and other stakeholders’ perceptions of the dynamics of fish stocks in ICES advice (WKAFPA)
The objective of the Workshop on accounting for fishers and other stakeholders’ perceptions of
the dynamics of fish stocks in ICES advice (WKAFPA) was to identify where and how stake-
holder information could be incorporated in the ICES fisheries advice process. It adopted an
operational definition of the concept of perception, where perceptions result from observations,
interpreted in light of experience, that can be supported by data, information and knowledge to
generate evidence about them. Stakeholder information can be either structured (e.g. routinely
collected information in a standardized format) or unstructured (e.g. experiential information)
and either of those can inform decisions made during the production of ICES advice.
Most notably, the group identified there was a need to engage with stakeholders earlier in the
process, i.e. before benchmarks meetings take place and before preliminary assessment results
are used as the basis to predict total allowable catches for upcoming advice (Figure 4.2). It was
therefore recommended to include in the ICES process the organisation of pre-bench-
mark/roadmap workshops where science and data needs of upcoming benchmarks can be iden-
tified, followed by making arrangements how scientists and stakeholders can collaborate to ac-
cess, prepare for use (where relevant) and document the structured and unstructured infor-
mation well ahead of the benchmark meetings.
It was also recommended to organise ‘sense-checking’ sessions with stakeholders when prelim-
inary assessments are available but not yet used as the basis for advisory production. This would
allow stakeholders and assessment scientists to verify available knowledge and data against
stock perceptions and provide additional considerations relevant for the production of TAC ad-
vice. Next to these two additional activities, it is recommended that communication on differ-
ences in stakeholder perception or data derived perceptions are communicated within the ICES
assessment reports as well as in the ICES advice in a transparent manner. Not only should dif-
ferences or similarities be documented and communicated, in those cases where there are differ-
ences in perception between ICES stock assessments and stakeholders, a working group, external
to the assessment working groups, should evaluate these differences and describe whether these
differences can be logically explained or require further investigation. This outcome of this pro-
cess may potentially lead to new data collection or additional analyses suitable for input to
benchmarks.
Essential in this entire process is making sure the same language is spoken between scientists
and stakeholders, that there are clear and transparent processes in place on how to deal with
stakeholder information and communicate clearly how this information is used in the prepara-
tion of ICES advice.info:eu-repo/semantics/publishedVersio
Workshop to review and progress the reported lists of eu msfd descriptor 3 ( (WKD3LISTS)
info:eu-repo/semantics/publishedVersio
Implications of Extreme Life Span in Clonal Organisms: Millenary Clones in Meadows of the Threatened Seagrass Posidonia oceanica
The maximum size and age that clonal organisms can reach remains poorly known, although we do know that the largest natural clones can extend over hundreds or thousands of metres and potentially live for centuries. We made a review of findings to date, which reveal that the maximum clone age and size estimates reported in the literature are typically limited by the scale of sampling, and may grossly underestimate the maximum age and size of clonal organisms. A case study presented here shows the occurrence of clones of slow-growing marine angiosperm Posidonia oceanica at spatial scales ranging from metres to hundreds of kilometres, using microsatellites on 1544 sampling units from a total of 40 locations across the Mediterranean Sea. This analysis revealed the presence, with a prevalence of 3.5 to 8.9%, of very large clones spreading over one to several (up to 15) kilometres at the different locations. Using estimates from field studies and models of the clonal growth of P. oceanica, we estimated these large clones to be hundreds to thousands of years old, suggesting the evolution of general purpose genotypes with large phenotypic plasticity in this species. These results, obtained combining genetics, demography and model-based calculations, question present knowledge and understanding of the spreading capacity and life span of plant clones. These findings call for further research on these life history traits associated with clonality, considering their possible ecological and evolutionary implications
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