Global (e.g. climate change) and local factors (e.g. nutrient enrichment) act together in nature strongly hammering coastal ecosystems, where seagrasses play a critical ecological role. This ...experiment explores the combined effects of warming, acidification and ammonium enrichment on the seagrass Cymodocea nodosa under a full factorial mesocosm design. Warming increased plant production but at the expense of reducing carbon reserves. Meanwhile, acidification had not effects on plant production but increased slightly carbon reserves, while a slight stimulation of net production and a slight decrease on carbon reserves under ammonium supply were recorded. When all the factors were combined together improved the production and carbon reserves of Cymodocea nodosa, indicating that acidification improved ammonium assimilation and buffered the enhanced respiration promoted by temperature. Therefore, it could indicate that this temperate species may benefit under the simulated future scenarios, but indirect effects (e.g. herbivory, mechanical stress, etc.) may counteract this balance.
•A significant synergy can occur when several environmental factors interact.•Warming positively affect plant production but at expense of reducing carbon reserves.•Loss leaf rates increased with ammonium supply•CO2 increase did not produce significant effects.•Future scenarios may benefit to C. nodosa improving their growth and carbon reserves.
Seagrass beds act as blue carbon sinks globally as they enhance the trapping of recalcitrant (i.e., low biodegradability) organic carbon in their sediments. Recent studies also show that the ...recalcitrant fraction of the dissolved organic carbon (DOC) pool in seawater has an important role as long-term carbon sequestration in oceans. Although seagrasses are known for the large amount of DOC they export, little attention has been given to its biodegradability, which ultimately determinates its fate in the coastal carbon cycle. In turn, invasive algae are a major global concern in seagrass ecosystems since they can deeply modify their structure and functions, which may affect carbon metabolism and DOC release. This work assesses how the presence of Halimeda incrassata, an invasive tropical calcareous macroalga, modifies carbon metabolism and DOC fluxes in invaded areas dominated by the seagrass Cymodocea nodosa. Our results show that stands with the presence of this seagrass (i.e., both monospecific and mixed meadow) had the highest production values, acting as high DOC producers in both winter (mainly of labile DOC; DOCL) and summer (mainly as recalcitrant DOC; DOCR). In contrast, monospecific H. incrassata beds exhibited low production values, and the presence of this macroalga (either as monospecific beds or mixed with C. nodosa) triggered the shift from a net DOC-producing-system in summer (mainly DOCL) to a net DOC-consuming-system in winter. This work thus suggests that C. nodosa meadows have the potential to export a significant fraction of both labile and recalcitrant DOC, and that the spread of this invasive alga might decrease the C export capacity of seagrass meadows. Such shift would imply the reduction of a quick and efficient transfer of carbon and energy to higher trophic levels, and might reduce the blue carbon potential of seagrasses as dissolved form in the water column.
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•C. nodosa exports a significant fraction of both labile and recalcitrant DOC.•H. incrassata tends to release mainly labile DOC or act as DOC consumer.•The spread of H. incrassata into seagrass can decrease the export of carbon as DOC.•H. incrassata invasion causes lower organic carbon uptake, which might affect C sinks.•Seagrasses contribute to blue carbon sequestration via recalcitrant DOC production.
Coastal development and climate change are sparking growing concern about the vulnerability of the organic carbon (OC) stocks in marine sediments to remineralization, especially in high threaten ...coastal ecosystems like seagrass meadows. Uncertainties still exist regarding the role played by hydrodynamics, seagrass canopies and sediment properties in OC resuspension and remineralization. A set of laboratory experiments were conducted to assess, for the first time, the mechanisms by which the particulate and dissolved organic carbon (POC and DOC) may be released and remineralized under hydrodynamic conditions (i.e., unidirectional and oscillatory flows) in two eelgrass densities and sediments properties (i.e., grain size and OC content). After a gradually increase in hydrodynamic forces, our results demonstrated that the presence of eelgrass reduced sediment erosion and OC loss in high-density canopies, while low-density canopies promote OC resuspension (on average, 1.8-fold higher than high-density canopies). We also demonstrated that unidirectional and oscillatory flows released similar DOC from surface sediments (on average, 15.5 ± 1.4 and 18.4 ± 1.8 g m
, respectively), whereas oscillatory flow released significantly more POC than unidirectional flows (from 10.8 ± 1.1 to 32.1 ± 5.6 g m
for unidirectional and oscillatory flows, respectively). POC and DOC released was strongly influenced by both seagrass meadow structure (i.e., lower eelgrass density and shoot area) and sediment properties (i.e., lower mud and higher sediment water content). We found that, although >74 % of OC in upper sediments was remineralized within 30 days, a relatively high amount of OC in high-density canopies is recalcitrant, highlighting its potential for the formation of blue carbon deposits. This study highlights the vulnerability of OC deposits in seagrass sediments to resuspension if the meadow is degraded and/or the climate change yield stronger storms, which could potentially weaken the seagrass meadows' service as blue carbon ecosystem in the future.
The dissolved organic carbon (DOC) leached from two types of microplastics (polyethylene and polypropylene) frequently found in coastal areas were evaluated in situ. Subsequently, the bioavailability ...of leached DOC was assessed for microbial inocula from different coastal communities (i.e., estuarine and open-coastal waters, river-mouth waters and seagrass beds). Leached DOC was largely biodegradable (as much as 85 %). However, seagrass beds and river-mouth waters exhibited lower DOC utilization efficiency than estuarine and open-coastal waters, probably because of differences in their microbial communities. The labile/recalcitrant ratio of DOC leached from plastic was similar under illuminated and dark conditions, whereas DOC leached from polyethylene, rather than DOC leached from polypropylene, was preferentially used by microbial communities. We estimated that as many as 21,000 metric tons of DOC leached from plastics may be released into ocean annually. Our results support the need to consider the potential impacts of coastal plastic pollution on microbial communities, including consideration of the trophic webs and coastal carbon cycle.
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•Dissolved organic carbon (DOC) leached from plastic followed a logarithmic function.•Light rather than salinity affect to DOC leached from plastics.•DOC leached from plastics were greatly biodegradable (as much as 85 %).•Seagrass beds and river-mouth waters exhibited lower DOC utilization efficiency.•Polyethylene-derived DOC was preferential used than polypropylene-derived DOC.
Cadiz Bay is a shallow mesotidal lagoon with extensive populations of the seagrass Cymodocea nodosa at intertidal and shallow subtidal elevations. This work aims to understand the mechanisms behind ...the resilience of this species to gradual sea level rise by studying its acclimation capacity to depth along the shallow littoral, and therefore, to gradual variations in the light environment. To address this objective, these populations have been monitored seasonally over a 10 year period, representing the longest seasonal database available in the literature for this species. The monitoring included populations at 0.4, −0.08 and −0.5 m LAT. The results show that C. nodosa has a strong seasonality for demographic and shoot dynamic properties – with longer shoots and larger growth in summer (high temperature) than in winter (low temperature), but also some losses. Moreover, shoots have different leaf morphometry depending on depth, with small and dense shoots in the intertidal areas (0.4 m) and sparse large shoots in the subtidal ones (−0.08 and 0.5 m). These differences in morphometry and shoot dynamic properties, combined with the differences in shoot density, explain the lack of differences in meadow production balance (i.e. meadow growth – meadow losses) between the intertidal (0.4 m) and the deepest population (−0.5 m), supporting the long term resilience of Cymodocea nodosa in Cadiz Bay. This study contributes to the understanding of the mechanisms behind seagrass stability and resilience, which is particularly important towards predicting the effects of climate change on these key coastal ecosystems, and also highlights the value of continuous long-term monitoring efforts to evaluate seagrass trajectories.
•This work presents the longest seasonal database available in literature for Cymodocea nodosa.•C. nodosa acclimates to differences in light availability through morphometric changes.•C. nodosa morphotypes have different growth rate and shoot density.•Morphometric acclimation supports the long-term resilience of C. nodosa meadows in shallow environments.•Water quality and accommodation space are going to be crucial for the adaptation of this species to Sea Level Rise.
Eutrophication is one of the major threats facing seagrasses, promoting effects in different compartments of the community (e.g. plants, epiphytes, fauna). In this study, we researched how in situ ...nutrient enrichment modified the consumption rates of Cymodocea nodosa plants during a period of 3 mo, by creating a set of mesocosm feeding choice experiments with the generalist herbivore Paracentrotus lividus. Nutrient enrichment intensified the consumption of C. nodosa leaves by increasing the palatability of their tissues at different levels. At a first level (i.e. the individual plant response), nutritional quality of the tissues increased (i.e. nitrogen content), while both biomechanical (i.e. absolute force-to-tear, F
TA, and specific force-to-tear, F
TS) and mechanical (i.e. fiber content) traits were reduced. At a second level, the presence of epiphytes coating the leaves increased their nutritional quality without actually increasing their biomechanical resistance, which rendered higher consumption rates. However, the presence of Ulva sp. (a highly palatable macrophyte) reduced the direct consumption of C. nodosa leaves, mainly when coated by epiphytes, a fact fully endorsed by the compensatory feeding theory. Therefore, the nutritional quality of the C. nodosa leaves is a key factor regulating their susceptibility to be consumed, although mechanical and biomechanical factors also gained importance when nutritional quality was low. In addition, the presence of other components of the community (epiphytes and macroalgae) may increase or reduce herbivore pressure, highlighting the complex nature of herbivore–plant interrelationships.
Large‐scale losses of seagrass areas have been associated with eutrophication events, which have led to an overproduction of photosynthetic organisms including epiphytes. Grazers that feed on ...epiphytes can exert a significant top–down control in the system, but the effects of physical factors on grazing activity and feeding behaviour have been rarely examined. We addressed the combination of hydrodynamic regime and seagrass shoot density can alter the feeding and foraging behaviours of mesograzers. A full factorial experiment, with flow velocity (high, medium and low) and shoot density (high versus low) as main factors, was conducted in a racetrack flume using artificial seagrass plots. The results showed that when high flow velocity conditions were combined with low shoot density, consumption of epiphytes by mesograzers was strongly reduced. In contrast, when flow velocity was low or shoot density was high, mesograzers exhibited high feeding rates and vigorous swimming behaviour. These results clearly indicate that hydrodynamic stress reduces the time that mesograzers can spend feeding, since it inhibits their swimming behaviour, and thus indirectly affecting to the density of epiphytes. Therefore, the triggering of trophic cascade effects in seagrass communities under these experimental conditions depended on the interrelationship and feedbacks among shoot density, abiotic (flow velocity) and biotic (epiphytes and mesograzers) compartments, with flow velocity exerting a top–down control on seagrass ecosystems.
Seagrasses can use both ammonium (NH
4
+
) and nitrate (NO
3
-
) as inorganic nitrogen (N) sources. However, NO
3
-
uptake and assimilation are energetically more expensive and tightly regulated than ...NH
4
+
uptake. The objective of this study was to test the complex interactive effects between different forms of N enrichment (NH
4
+
and NO
3
-
) and light levels on the morphological and physiological traits in the intertidal seagrass
Zostera noltei
. Plants were cultured over 40 d under 2 levels of light (low and high) with 2 inorganic N concentrations supplied at the same dose, NO
3
-
(25 µM) and NH
4
+
(25 µM), and a control, following a 2-factorial design. Results showed a differential response in
Z. noltei
depending on the inorganic N source and light dose. NH
4
+
enrichment negatively affected almost all morphometric and dynamic variables analyzed, both in isolation and combined with low light conditions. In contrast, NO
3
-
enrichment had a positive effect on
Z. noltei
survival compared with the control treatment in terms of net growth rate and rhizomatic growth, mainly under high light conditions. Therefore, our study demonstrated that the effects promoted by nutrient enrichment largely depend on the source of N used. Light levels play a crucial role in this response by potentially shifting the effects from toxic (under low light) to beneficial (under high light) when NO
3
-
is the main N source. Our findings highlight that N form in eutrophication events should be considered when evaluating the potential impacts of nutrient enrichment and light reduction on seagrass communities.
The sports business has become one of the fastest-growing industries in recent years. Sports organizations now have the potential to generate massive amounts of revenue through a variety of different ...channels, including broadcasting rights, advertising and branding. However, the rise of sports-related business has so far received relatively little attention from management scholars and social scientists. This book argues that we can no longer afford to ignore this important economic and social phenomenon. It presents a conceptual framework based on the concept of value creation to show how we can understand and explain the success and failure of sports organizations. Key concepts are illustrated with case studies of sporting organizations, including Real Madrid, FC Barcelona and the Americas Cup. Written by a team of authors from one of Spain's leading business schools, it provides a unique set of theoretical and practical insights for researchers and sports organization managers.
To improve quality of newborn screening by tandem mass spectrometry with a novel approach made possible by the collaboration of 154 laboratories in 49 countries.
A database of 767,464 results from ...12,721 cases affected with 60 conditions was used to build multivariate pattern recognition software that generates tools integrating multiple clinically significant results into a single score. This score is determined by the overlap between normal and disease ranges, penetration within the disease range, differences between conditions, and weighted correction factors.
Ninety tools target either a single condition or the differential diagnosis between multiple conditions. Scores are expressed as the percentile rank among all cases with the same condition and are compared to interpretation guidelines. Retrospective evaluation of past cases suggests that these tools could have avoided at least half of 279 false-positive outcomes caused by carrier status for fatty-acid oxidation disorders and could have prevented 88% of known false-negative events.
Application of this computational approach to raw data is independent from single analyte cutoff values. In Minnesota, the tools have been a major contributing factor to the sustained achievement of a false-positive rate below 0.1% and a positive predictive value above 60%.
Genet Med advance online publication 16 February 2012
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