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1.
Sci Total Environ ; 954: 175985, 2024 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-39233073

RESUMO

Microplastic (plastics <5 mm; MP) contamination in the marine environment has gained global attention due to its continuous accumulation and serious threats to ecosystems. This review evaluates patterns of MP accumulation in seagrasses, mangroves, and saltmarshes to provide an integrated view of MP pollution. Since 2011, studies have examined the sources, distribution, characterization, and fate of MPs in these habitats. We found an unequal geographic distribution with most studies conducted in the Northern Hemisphere and in mangroves, which have the highest MP concentrations compared to saltmarshes and seagrass beds, particularly near urban centers and fishing zones. Almost 40 % of the outcomes of our meta-analysis show a higher MP accumulation in vegetated than unvegetated sites. Also, degraded and highly-degraded sites exhibited higher amounts of MPs than less-degraded areas. In addition, secondary MPs are the dominant form, with less dense polymers (polyethylene, polystyrene, and polypropylene) being more abundant and blue, black, and transparent the most common colors. Methodological differences in reporting units, sampling depths, and extraction methods reduce study comparability and increase variability. This review provides a comprehensive understanding of MP research in coastal ecosystems, revealing critical knowledge gaps affecting MP distribution, such as vegetation density, diversity, and hydrodynamics, and emphasizes the need for standardized methodologies for accurate comparisons.

2.
Sci Total Environ ; 950: 175224, 2024 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-39098408

RESUMO

Coastal wetlands are crucial in climate change regulation due to their capacity to act as either sinks or sources of carbon, resulting from the balance between greenhouse gas (GHG) emissions, mainly methane (CH4), and soil carbon sequestration. Despite the paramount role of wetlands in climate regulation few studies investigate both aspects. The Camargue is one of the largest wetlands in Europe, yet the ways in which environmental and anthropic factors drive carbon dynamics remain poorly studied. We examined GHG emissions and soil organic carbon (SOC) stocks and accumulation rates in twelve representative wetlands, including two rice fields, to gain insights into the carbon dynamics and how it is influenced by hydrology and salinity. Mean CH4 rates ranged between - 87.0 and 131.0 mg m-2 h-1and the main drivers were water conductivity and redox, water table depth and soil temperature. High emission rates were restricted to freshwater conditions during summer flooding periods whereas they were low in wetlands subjected to summer drought and water conductivity higher than 10 mS cm-1. Nitrous oxide emissions were low, ranging from - 0.5 to 0.9 mg N2O m-2 h-1. The SOC stocks in the upper meter ranged from 17 to 90 Mg OC ha-1. Our research highlights the critical role of low-saline wetlands in carbon budgeting which potentially are large sources of CH4 but also contain the largest SOC stocks in the Camargue. Natural hydroperiods, involving summer drought, can maintain them as carbon sinks, but altered hydrology can transform them into sources. Artificial freshwater supply during summer leads to substantial CH4 emissions, offsetting their SOC accumulation rates. In conclusion, we advocate for readjusting the altered hydrology in marshes and for the search of management compromises to ensure the compatibility of economic and leisure activities with the preservation of the inherent climate-regulating capacity of coastal wetlands.

3.
Sci Total Environ ; 931: 173006, 2024 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-38710389

RESUMO

The rise in sea level and land subsidence are seriously threatening the diversity of tidal morphologies that have made the Venice Lagoon such a distinctive landscape. Here, we assess the vulnerability of tidal morphologies to relative sea-level rise based on a new conceptual framework that accounts for both above- and below-sea-level zones, sedimentary architecture, and surface morphology. Around 80 % of the lagoon area will face moderate to severe vulnerability by 2050, doubling compared to the 1990s. While the subtidal zone may be relatively less threatened compared to past conditions, the drastic decline in intertidal morphologies is alarming. This contributes to the flattening and deepening of the lagoon topography and thus to the loss of lagoon landscape diversity, likely leading to a decrease in the ecosystem services the tidal morphologies provide. The interconnection of intertidal and subtidal morphologies is crucial for maintaining the overall health and functionality of the lagoon's ecosystem. Any disruption to one aspect can have ripple effects throughout the entire system.

4.
Sci Total Environ ; 923: 171443, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38447727

RESUMO

Saltmarshes play a crucial role in carbon sequestration and storage, although they are increasingly threatened by climate change-induced sea level rise (SLR). This study assessed the potential variation in Blue Carbon stocks across regional and local scales, and estimated their economic value and potential habitat loss due to SLR based on the IPCC AR6 scenarios for 2050 and 2100 in three estuarine saltmarshes in northern Portugal, the saltmarshes of the Minho, Lima and Cávado estuaries. The combined carbon stock of these saltmarshes was 38,798 ± 2880 t of organic carbon, valued at 3.96 ± 0.38 M€. Local and regional differences in carbon stocks were observed between common species, with the cordgrass Spartina patens and the reed Phragmites australis consistently showing higher values in the Lima saltmarsh in some of the parameters. Overall, the Lima saltmarsh had the highest total carbon per species cover, with S. patens showing the highest values among common species. Bolboschoenus maritimus had the highest values in the Minho saltmarsh, while the other species presented a similar carbon storage capacity. Potential habitat loss due to SLR was most evident in the Cávado saltmarsh over shorter timescales, with a significant risk of inundation even for median values of SLR, while the Lima saltmarsh was shown to be more resistant and resilient. If habitat loss directly equates to carbon loss within these saltmarshes, projected CO2 emissions may range from 22,000 to 43,449 t by 2050 and 33,000 to 130,000 t by 2100 (under the IPCC SSP5-8.5 scenario). The study shows the importance of Blue Carbon site-specific estimates, acknowledging the potential future repercussions from habitat loss due to SLR. It emphasizes the need to consider local and regional variability in Blue Carbon stocks assessments and highlights the critical importance of preserving and rehabilitating these ecosystems to ensure their continued efficacy as vital carbon sinks, thereby contributing to climate change mitigation efforts.

5.
Sci Total Environ ; 886: 163957, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37164078

RESUMO

The implementation of climate change mitigation strategies based on the conservation and restoration of Blue Carbon ecosystems requires a deep understanding of the magnitude and variability in organic carbon (Corg) storage across and within these ecosystems. This study explored the variability in soil Corg stocks and burial rates across and within intertidal estuarine habitats of the Atlantic European coast and its relation to biotic and abiotic drivers. A total of 136 soil cores were collected across saltmarshes located at different tidal zones (high marsh, N = 45; low marsh, N = 30), seagrass meadows (N = 17) and tidal flats (N = 44), and from the inner to the outer sections of five estuaries characterized by different basin land uses. Soil Corg stocks were higher in high-marsh communities (65 ± 3 Mg ha-1) than in low-marsh communities (38 ± 3 Mg ha-1), seagrass meadows (40 ± 5 Mg ha-1) and unvegetated tidal flats (46 ± 3 Mg ha-1) whereas Corg burial rates also tended to be higher in high marshes (62 ± 13 g m-2 y-1) compared to low marshes (43 ± 15 g m-2 y-1) and tidal flats (35 ± 9 g m-2 y-1). Soil Corg stocks and burial rates decreased from inner to outer estuarine sections in most estuaries reflecting the decrease in the river influence towards the estuary mouth. Higher soil Corg stocks were related to higher content of silt and clay and higher proportion of forest and natural land within the river basin, pointing at new opportunities for protecting coastal natural carbon sinks based on the conservation and restoration of upland ecosystems. Our study contributes to the global inventory of Blue Carbon by adding data from unexplored regions and habitats in Europe, and by identifying drivers of variability across and within estuaries.


Assuntos
Carbono , Ecossistema , Sedimentos Geológicos , Áreas Alagadas , Sequestro de Carbono , Solo
6.
Sci Total Environ ; 859(Pt 2): 160483, 2023 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-36435254

RESUMO

Globally, sea-level rise (SLR) is a major environmental challenge for coastal ecosystems. Of particular concern are the impacts on intertidal wetlands, the loss of which would have detrimental consequences for both human and ecological communities. On the south-east Australian coast, case studies suggest that the future of intertidal wetlands will greatly depend on landward migration as surface accretion may not keep up with the predicted SLR in many estuaries. However, due to differences in geomorphological settings and land-use, estuaries vary in their capacity to accommodate lateral migration. Regional scale assessment of the lateral accommodation space is therefore critical for pre-emptive planning to conserve these valuable coastal ecosystems. In this study, we analysed wetland lateral accommodation space distribution within 110 estuaries under three SLR scenarios and three land management options on the New South Wales coast, south-east Australia. From the wetland distribution predictions, we calculated and mapped the lateral accommodation space in each estuary associated with each sea level and land use scenario. We further investigated the relationships between wetland migration capacity, intertidal hypsometry represented by elevation skewness, and estuary type within a Bayesian analysis framework. Our results showed that while a few large riverine estuaries dominated the state's total accommodation space, saline wetlands were at risk of disappearing from most intermittently closed-open estuaries if they cannot vertically accrete at the pace of SLR. These distinct responses to SLR are due to different elevation distributions. Furthermore, our assessment of land use adaptation options suggested that the promotion of landward migration without impairing other important ecosystems could be achieved by making low intensity land uses available within several riverine estuaries and barrier (open entrance) estuaries. Through identifying migration opportunities and barriers, the findings of the study could support regional scale adaptation strategies to ensure the sustainability of wetland-associated ecosystem goods and services.


Assuntos
Ecossistema , Elevação do Nível do Mar , Austrália , Teorema de Bayes , Áreas Alagadas
7.
Microorganisms ; 10(11)2022 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-36363713

RESUMO

The capacity of Blue Carbon Ecosystems to act as carbon sinks is strongly influenced by the metabolism of soil-associated microbes, which ultimately determine how much carbon is accumulated or returned to the atmosphere. The rapid evolution of sequencing technologies has facilitated the generation of tremendous amounts of data on what taxa comprise belowground microbial assemblages, largely available as isolated datasets, offering an opportunity for synthesis research that informs progress on understanding Blue Carbon microbiomes. We identified questions that can be addressed with a synthesis approach, including the high variability across datasets, space, and time due to differing sampling techniques, ecosystem or vegetation specificity, and the relationship between microbiome community and edaphic properties, particularly soil carbon. To address these questions, we collated 34 16S rRNA amplicon sequencing datasets, including bulk soil or rhizosphere from seagrass, mangroves, and saltmarshes within publicly available repositories. We identified technical and theoretical challenges that precluded a synthesis of multiple studies with currently available data, and opportunities for addressing the knowledge gaps within Blue Carbon microbial ecology going forward. Here, we provide a standardisation toolbox that supports enacting tasks for the acquisition, management, and integration of Blue Carbon-associated sequencing data and metadata to potentially elucidate novel mechanisms behind Blue Carbon dynamics.

8.
Ecol Evol ; 11(7): 3274-3285, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33841783

RESUMO

We examined whether the presence or absence of different environmental stressors influenced the reproductive potential of a saltmarsh species-Plantago maritima. We focused on total seed output, seed quality, and biomass of progeny. So far, there are no studies trying to answer the question of how different saltmarsh management affects the quality of seed in saltmarsh species. For the purposes of the study, plots subjected to light mowing, light or heavy grazing, trampling, or rooting were designated in three nature reserves in Poland. On each plot, the abundance of infructescences per sq. meter was calculated. Mature infructescences were collected, and their length and number of fruit capsules were measured. The seeds obtained from fruit capsules were weighted and sown in controlled conditions. The germination rate and the final germination percentage were calculated. A representative number of sprouts were grown. After a period of 2 months, the individuals of P. maritima were harvested and their total dry mass was measured. It was found that heavy grazing had the greatest effect on all of the studied characteristics. The presence of this factor resulted in shorter infructescences with a smaller number of fruit capsules. However, this phenomenon was compensated by the higher abundance of infructescences per sq. meter. At the same time, seeds produced by grazed individuals were significantly lighter. Interestingly, intensive trampling by people affected P. maritima individuals in a similar way to heavy grazing, while mowing and rooting had less impact on the considered characteristics. Although a positive correlation between seed mass and germination success was found, the altogether lower seed mass had a negligible effect on germination parameters. Also, the differences in seed parameters did not affect dry mass of obtained progeny grown in laboratory conditions. Synthesis and applications: Different environmental stressors, such as grazing and mowing, have an effect on reproductive potential of a saltmarsh species P. maritima. In the case of habitats created anthropogenically, such as brackish saltmarshes, the role of management is crucial for their conservation. Therefore, searching for the best active protection methods is important. In light of the results obtained, extensive or rotational grazing appears to be the best form of saltmarsh management.

9.
Sci Total Environ ; 724: 138225, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32408452

RESUMO

The competition-to-stress hypothesis suggests that some competitively disadvantaged species are excluded from higher inundation estuaries due to abiotic stress (high flooding level) and from lower inundation estuaries by competition. How abiotic and biotic stress interactions affect plant growth and whether competition intensity and importance are stable along environmental gradients is a controversial subject. We explored the influence of two factors, and we clarified that inundation stress and invasion competition are the main reasons leading to the traits exhibited by target plant Suaeda salsa and population presence changes. Our results indicated that when the flooding height exceeded 13.4 cm, the S. salsa mortality rate was 90%-100%. At the lower flooding heights (<13.4 cm), the S. salsa mortality rate when neighboring plants were present was 77.7%-100%, whereas, without neighbors it was 30.9%-83.7%. The invader Spartina alterniflora inhibited S. salsa plant height by 48%-77%, whereas the S. alterniflora inhibited S. salsa density by 11%-98% and reduced its biomass by 50.5%-90.1%. The changes in competition intensity and importance showed that the S. alterniflora had a distinct impact from the early germinant period to growing period (from May to July), finally stable no differences along the flooding height in the maturity period. At the same flooding level, the analysis of above and belowground competition by S. alterniflora showed that aboveground and belowground competition are the main causes of individual S. salsa inhibition. Our results confirm the competitive stress hypothesis, which is that competition shapes individual traits and population presence in the context of abiotic stress. This conclusion can guide the management and protection of native plants under biological invasion in a stressful environment.


Assuntos
Chenopodiaceae , Estuários , China , Inundações , Poaceae , Áreas Alagadas
10.
Chemosphere ; 242: 125174, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31675582

RESUMO

Salt marshes are natural deposits of heavy metals in estuarine systems, where sulphide precipitation associated with redox changes often results in a natural attenuation of contamination. In the present study, we focus on the effects of variable redox conditions imposed to a highly-polluted phosphogypsum stack that is directly piled over the salt marsh soil in the Tinto River estuary (Huelva, Spain). The behaviour of contaminants is evaluated in the phosphogypsum waste and in the marsh basement, separately, in controlled, experimentally-induced oscillating redox conditions. The results revealed that Fe, and to a lesser extent S, control most precipitation/dissolution processes. Ferric iron precipitates in the form of phosphates and oxyhydroxides, while metal sulphide precipitation is insignificant and appears to be prevented by the abundant formation of Fe phosphates. An antagonistic evolution with changing redox conditions was observed for the remaining contaminants such as Zn, As, Cd and U, which remained mobile in solution during most of experimental run. Therefore, these findings revealed that high concentrations of phosphates inhibit the typical processes of immobilisation of pollutants in salt-marshes which highlights the elevated contaminant potential of phosphogypsum wastes on coastal environments.


Assuntos
Sulfato de Cálcio/química , Estuários , Oxirredução , Fósforo/química , Monitoramento Ambiental/métodos , Ferro/química , Metais Pesados/análise , Fosfatos/química , Rios , Espanha , Poluentes Químicos da Água/análise , Áreas Alagadas
11.
Sci Total Environ ; 652: 1113-1128, 2019 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-30586798

RESUMO

The Baixo Vouga Lagunar (BVL) is part of Ria de Aveiro coastal lagoon in Portugal, which is classified as a Special Protection Area under the European Habitats and Birds Directives. This part of the system, corresponding to the confluence of the Vouga River with the lagoon, is very important culturally and socioeconomically for the local communities, taking place several human activities, especially agriculture. To prevent salt water intrusion from the Ria de Aveiro into agriculture fields, a floodbank was initiated in the 90's. In frame of ongoing changes in Ria de Aveiro hydrodynamics, the existing floodbank will be now extended, introducing further changes in the ecological dynamics of the BVL and its adjacent area. As a consequence, the water level in the floodbank downstream side is expected to rise, increasing the submersion period in tidal wetlands, and leading to coastal squeeze. The aim of this study is to apply an ecosystem based-management approach to mitigate the impacts on biodiversity resulting from the management plan. To do so, we have modelled the implications of the changes in several hydrological and environmental variables on four saltmarsh species and habitats distribution, as well as on their associated ecosystem services, both upstream and downstream of the floodbank. The ecosystem services of interest were prioritized by stakeholders' elicitation, which were then used as an input to a spatial multi-criteria analysis aimed to find the best management actions to compensate for the unintended loss of biodiversity and ecosystem services in the BVL. According to our results, the main areas to be preserved in the BVL were the traditional agricultural mosaic fields; the freshwater courses and the subtidal estuarine channels. By combining ecology with the analysis of social preferences, this study shows how co-developed solutions can support adaptive management and the conservation of coastal ecosystems.

12.
Glob Chang Biol ; 25(3): 1063-1077, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30589156

RESUMO

Because coastal habitats store large amounts of organic carbon (Corg ), the conservation and restoration of these habitats are considered to be important measures for mitigating global climate change. Although future sea-level rise is predicted to change the characteristics of these habitats, its impact on their rate of Corg sequestration is highly uncertain. Here we used historical depositional records to show that relative sea-level (RSL) changes regulated Corg accumulation rates in boreal contiguous seagrass-saltmarsh habitats. Age-depth modeling and geological and biogeochemical approaches indicated that Corg accumulation rates varied as a function of changes in depositional environments and habitat relocations. In particular, Corg accumulation rates were enhanced in subtidal seagrass meadows during times of RSL rise, which were caused by postseismic land subsidence and climate change. Our findings identify historical analogs for the future impact of RSL rise driven by global climate change on rates of Corg sequestration in coastal habitats.


Assuntos
Sequestro de Carbono , Ecossistema , Monitoramento Ambiental , Estuários , Água do Mar/análise , Carbono/análise , Carbono/metabolismo , Mudança Climática , Conservação dos Recursos Naturais , Sedimentos Geológicos/análise , Plantas/metabolismo
13.
Environ Pollut ; 241: 136-147, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29804046

RESUMO

Microbial communities play vital roles in the biogeochemistry of nutrients in coastal saltmarshes, ultimately controlling water quality, nutrient cycling, and detoxification. We determined the structure of microbial populations inhabiting coastal saltmarsh sediments from northern Barataria Bay, Louisiana, USA to gain insight into impacts on the biogeochemical cycles affected by Macondo oil from the 2010 Deepwater Horizon well blowout two years after the accident. Quantitative PCR directed toward specific functional genes revealed that oiled marshes were greatly diminished in the population sizes of diazotrophs, denitrifiers, nitrate-reducers to ammonia, methanogens, sulfate-reducers and anaerobic aromatic degraders, and harbored elevated numbers of alkane-degraders. Illumina 16S rRNA gene sequencing indicated that oiling greatly changed the structure of the microbial communities, including significant decreases in diversity. Oil-driven changes were also demonstrated in the structure of two functional populations, denitrifying and sulfate reducing prokaryotes, using nirS and dsrB as biomarkers, respectively. Collectively, the results from 16S rRNA and functional genes indicated that oiling not only markedly altered the microbial community structures, but also the sizes and structures of populations involved in (or regulating) a number of important nutrient biogeochemical cycles in the saltmarshes. Alterations such as these are associated with potential deterioration of ecological services, and further studies are necessary to assess the trajectory of recovery of microbial-mediated ecosystem functions over time in oiled saltmarsh sediment.


Assuntos
Poluição por Petróleo/análise , Microbiologia da Água , Poluentes Químicos da Água/análise , Áreas Alagadas , Bactérias/classificação , Bactérias/genética , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Golfo do México , Louisiana , RNA Ribossômico 16S/química , Qualidade da Água
14.
Microb Ecol ; 73(3): 539-555, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-27888292

RESUMO

Time series foraminiferal data were obtained from samples collected from three sites at Brancaster Overy Staithe, Burnham Overy Staithe and Thornham on the North Norfolk coast over a 1-year period. At each collection point, six environmental variables-temperature, chlorophyll, sand, mud, pH and salinity-were also measured. The principle aim of this study was to examine the benthic foraminiferal fauna in regard to the temporal variability of foraminiferal abundance, seasonal trend, dominant species, species diversity and the impact of environmental variables on the foraminiferal communities in the top 1 cm of sediment over a 1-year time series. The foraminiferal assemblages at the three sites were dominated by three species: Haynesina germanica, Ammonia sp. and Elphidium williamsoni. Foraminiferal species showed considerable seasonal and temporal fluctuation throughout the year at the three investigated sites. The foraminiferal assemblage at the three low marsh zones showed a maximum abundance in autumn between September and November and a minimum abundance observed between July and August. There were two separate peaks in the abundance of Ammonia sp. and E. williamsoni, one in spring and another in autumn. In contrast, H. germanica showed a single peak in its abundance in autumn. A generalized additive modelling approach was used to explain the variation in the observed foraminiferal abundance and to estimate the significant impact of each of the environmental variables on living foraminiferal assemblages, with taxa abundance as the dependent variable. When included in the model as predictors, most of the environmental variables contributed little in explaining the observed variation in foraminiferal species abundance. However, the hypotheses for differences amongst sites, salinity and pH were significant and explained most of the variability in species relative abundance.


Assuntos
Foraminíferos/classificação , Foraminíferos/isolamento & purificação , Sedimentos Geológicos/parasitologia , Água do Mar/parasitologia , Áreas Alagadas , Biodiversidade , Inglaterra , Meio Ambiente , Monitoramento Ambiental , Estações do Ano
15.
Microb Ecol ; 71(2): 290-303, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26271740

RESUMO

Saltmarshes are typically dominated by perennial grasses with large underground rhizome systems that can change local sediment conditions and be important in shaping the sediment microbial community. Factors such as salinity that control plant zonation in saltmarshes are also likely to influence the microbial community, but little is known as to whether microbial communities share distribution patterns with plants in these systems. To determine the extent to which microbial assemblages are influenced by saltmarsh plant communities, as well as to examine patterns in microbial community structure at local and regional scales, we sampled sediments at three saltmarshes in Louisiana, USA. All three systems exhibit a patchy distribution of Juncus roemerianus stands within a Spartina alterniflora marsh. Sediment samples were collected from the interior of several J. roemerianus stands as well as from the S. alterniflora matrix. Samples were assayed for extracellular enzyme activity and DNA extracted to determine microbial community composition. Denaturing gradient gel electrophoresis of rRNA gene fragments was used to determine regional patterns in bacterial, archaeal, and fungal assemblages, while Illumina sequencing was used to examine local, vegetation-driven, patterns in community structure at one site. Both enzyme activity and microbial community structure were primarily influenced by regional site. Within individual saltmarshes, bacterial and archaeal communities differed between J. roemerianus and S. alterniflora vegetated sediments, while fungal communities did not. These results highlight the importance of the plant community in shaping the sediment microbial community in saltmarshes but also demonstrate that regional scale factors are at least as important.


Assuntos
Bactérias/enzimologia , Bactérias/isolamento & purificação , Fungos/enzimologia , Fungos/isolamento & purificação , Sedimentos Geológicos/microbiologia , Magnoliopsida/microbiologia , Poaceae/microbiologia , Bactérias/classificação , Bactérias/genética , Proteínas de Bactérias/análise , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biodiversidade , Proteínas Fúngicas/análise , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Fungos/classificação , Fungos/genética , Sedimentos Geológicos/química , Louisiana , Magnoliopsida/crescimento & desenvolvimento , Filogenia , Poaceae/crescimento & desenvolvimento , Áreas Alagadas
16.
Biol Rev Camb Philos Soc ; 89(1): 232-54, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23980752

RESUMO

Worldwide, coastal systems provide some of the most productive habitats, which potentially influence a range of marine and terrestrial ecosystems through the transfer of nutrients and energy. Several reviews have examined aspects of connectivity within coastal seascapes, but the scope of those reviews has been limited to single systems or single vectors. We use the transfer of carbon to examine the processes of connectivity through multiple vectors in multiple ecosystems using four coastal seascapes as case studies. We discuss and compare the main vectors of carbon connecting different ecosystems, and then the natural and human-induced factors that influence the magnitude of effect for those vectors on recipient systems. Vectors of carbon transfer can be grouped into two main categories: detrital particulate organic carbon (POC) and its associated dissolved organic and inorganic carbon (DOC/DIC) that are transported passively; and mobile consumers that transport carbon actively. High proportions of net primary production can be exported over meters to hundreds of kilometers from seagrass beds, algal reefs and mangroves as POC, with its export dependent on wind-generated currents in the first two of these systems and tidal currents for the last. By contrast, saltmarshes export large quantities of DOC through tidal movement, while land run-off plays a critical role in the transport of terrestrial POC and DOC into temperate fjords. Nekton actively transfers carbon across ecosystem boundaries through foraging movements, ontogenetic migrations, or 'trophic relays', into and out of seagrass beds, mangroves or saltmarshes. The magnitude of these vectors is influenced by: the hydrodynamics and geomorphology of the region; the characteristics of the carbon vector, such as their particle size and buoyancy; and for nekton, the extent and frequency of migrations between ecosystems. Through a risk-assessment process, we have identified the most significant human disturbances that affect the integrity of connectivity among ecosystems. Loss of habitat, net primary production (NPP) and overfishing pose the greatest risks to carbon transfer in temperate saltmarsh and tropical estuaries, particularly through their effects on nekton abundance and movement. In comparison, habitat/NPP loss and climate change are likely to be the major risks to carbon transfer in temperate fjords and temperate open coasts through alteration in the amount of POC and/or DOC/DIC being transported. While we have highlighted the importance of these vectors in coastal seascapes, there is limited quantitative data on the effects of these vectors on recipient systems. It is only through quantifying those subsidies that we can effectively incorporate complex interactions into the management of the marine environment and its resources.


Assuntos
Ciclo do Carbono , Ecossistema , Oceanos e Mares , Animais , Conservação dos Recursos Naturais , Atividades Humanas , Humanos
17.
Oecologia ; 93(1): 128-138, 1993 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28313785

RESUMO

The consequences of philopatric and dispersal behaviours under changing environmental conditions were examined using data from the colony of Lesser Snow Geese (Anser caerulescens caerulescens) breeding at La Pérouse Bay, Manitoba, Canada. In response to increased population size and decreased food abundance over time, increasing numbers of family groups have been dispersing from the traditional feeding areas. Goslings from dispersed broods were significantly heavier (7.3%), and had longer culmens (3.1%), head lengths (2.6%) and marginally longer tarsi (1.9%) on average than goslings that remained within La Pérouse Bay itself. These differences were consistent in each of 5 years. There was no evidence that the larger size of dispersed goslings was due to either a tendency for larger adults to disperse to alternative sites, or increased mortality of smaller goslings among dispersed broods. The most likely cause for the larger size of goslings from dispersed broods was the significantly greater per capita availability of the preferred salt-marsh forage species at non-traditional brood-rearing areas. The larger goslings in non-traditional feeding areas showed significantly higher firstyear survival, suggesting that the use of deteriorating traditional feeding areas may currently be maladaptive in this population.

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