Exotic Halophila stipulacea is an introduced carbon sink for the Eastern Mediterranean Sea

Carbon and nitrogen storage in exotic Halophila stipulacea were compared to that in native Posidonia oceanica and Cymodocea nodosa meadows and adjacent unvegetated sediments of the Eastern Mediterranean Sea and to that in native H. stipulacea of the Red Sea at sites with different biogeochemical conditions and level of human pressure. Exotic H. stipulacea possessed considerable storing capacity, with 2-fold higher Corg stock (0.71 ± 0.05 kg m−2 in the top 20 cm of sediment) and burial (14.78 gCorg m−2 y−1) than unvegetated areas and C. nodosa meadows and, surprisingly, comparable to P. oceanica. N (0.07 ± 0.01 kg m−2) and Cinorg (14.06 ± 8.02 kg m−2) stocks were similar between H. stipulacea and C. nodosa or unvegetated sediments, but different to P. oceanica. Corg and N stocks were higher in exotic than native H. stipulacea populations. Based on isotopic mixing model, organic material trapped in H. stipulacea sediments was mostly allochthonous (seagrass detritus 17% vs seston 67%). Corg stock was similar between monospecific and invaded C. nodosa meadows by H. stipulacea. Higher stocks were measured in the higher human pressure site. H. stipulacea introduction may contribute in the increase of carbon sequestration in the Eastern Mediterranean

Strategy development and implementation amongst SMEs in construction: A case study approach of Greek firms

The strategy development in the SMEs has recently received attention however the majority of those researches are either judging the strategy or the lack of it, or trying to apply one of the existent strategy theories. All of them result to some level of failure. It is argued here that in order for any theoretical application to be fruitful, an understanding of their actual practice is necessary, so this research seeks to track the process of strategy development in small to medium enterprises in construction (SMEC). Based on semi-structured interviews, it tried to capture both managers' perception regarding strategy development, and the real processes, to secure some practical use of the findings for the firms. The outcomes recognise the fundamental distinction between SMEC seeking growth and those seeking survival with sufficient returns and identify a common pattern in strategic vision development, as issue recognition and respond based on intuition and research, affected mainly by local networks. They also indicate the importance of implicit and unconscious processes, other than the manager's perception, related to the firms' rate of growth and based on the firms' attitude towards change in relation to its current capabilities. Stakeholders of those processes are also identified

A Tight Interaction between the Native Seagrass Cymodocea nodosa and the Exotic Halophila stipulacea in the Aegean Sea Highlights Seagrass Holobiont Variations

Seagrasses harbour bacterial communities with which they constitute a functional unit called holobiont that responds as a whole to environmental changes. Epiphytic bacterial communities rapidly respond to both biotic and abiotic factors, potentially contributing to the host fitness. The Lessepsian migrant Halophila stipulacea has a high phenotypical plasticity and harbours a highly diverse epiphytic bacterial community, which could support its invasiveness in the Mediterranean Sea. The current study aimed to evaluate the Halophila/Cymodocea competition in the Aegean Sea by analysing each of the two seagrasses in a meadow zone where these intermingled, as well as in their monospecific zones, at two depths. Differences in holobionts were evaluated using seagrass descriptors (morphometric, biochemical, elemental, and isotopic composition) to assess host changes, and 16S rRNA gene to identify bacterial community structure and composition. An Indicator Species Index was used to identify bacteria significantly associated with each host. In mixed meadows, native C. nodosa was shown to be affected by the presence of exotic H. stipulacea, in terms of both plant descriptors and bacterial communities, while H. stipulacea responded only to environmental factors rather than C. nodosa proximity. This study provided evidence of the competitive advantage of H. stipulacea on C. nodosa in the Aegean Sea and suggests the possible use of associated bacterial communities as an ecological seagrass descriptor

Aquaculture and eelgrass Zostera marina interactions in temperate ecosystems

This paper reviews the impacts of shellfish and finfish aquaculture on eelgrassZostera marina, the most widely distributed seagrass species in the northern hemisphere. Shellfish aquaculture can have positive, neutral, and negative effects on eelgrass. Positive interactions can be generated by the filtering activity of cultured bivalves, which may improve water quality and reduce epiphyte loads, and shellfish biodeposits may provide more nutrients to eelgrass and other vegetation. However, negative responses are more commonly reported and can be causedby shading and sedimentation. These negative effects tend to occur directly under and immediately surrounding shellfish farms and rapidly diminish with increasing distance. In contrast to shellfish aquaculture, only one field study has investigated the effects of finfish aquaculture on eelgrass in a temperate setting, and the results were inconclusive. However, many studies have investigated the effects of Mediterranean finfish farms on 2 other species of seagrass (Posidoniaoceanica and Cymodocea nodosa). These studies reported clear negative interactions, which have been linked to increased nutrient concentrations, sulphides, sedimentation, epiphyte loads, and grazing pressure. It is unknown if these studies are relevant for finfish aquaculture in temperate regions due to differences in environmental conditions, and because the studies focused on differ-ent species of seagrass. Thus, further study in a temperate setting is warranted. We conclude by highlighting key research gaps that could help regulators establish unambiguous operational and siting guidelines that minimize the potential for negative interactions between aquaculture and eelgrass

Blink: Fast Connectivity Recovery Entirely in the Data Plane

We present Blink, a data-driven system that leverages TCPinduced signals to detect failures directly in the data plane. The key intuition behind Blink is that a TCP flow exhibits a predictable behavior upon disruption: retransmitting the same packet over and over, at epochs exponentially spaced in time. When compounded over multiple flows, this behavior creates a strong and characteristic failure signal. Blink efficiently analyzes TCP flows to: (i) select which ones to track; (ii) reliably and quickly detect major traffic disruptions; and (iii) recover connectivity—all this, completely in the data plane. We present an implementation of Blink in P4 together with an extensive evaluation on real and synthetic traffic traces. Our results indicate that Blink: (i) achieves sub-second rerouting for large fractions of Internet traffic; and (ii) prevents unnecessary traffic shifts even in the presence of noise. We further show the feasibility of Blink by running it on an actual Tofino switch

Does ICCAT need ecosystem plans? a pilot ecosystem plan for the Atlantic tropical ecoregion.

The implementation of an Ecosystem Approach Fisheries Management (EAFM) in ICCAT has been slow and patchy, as it lacks a long-term plan, vision and guidance on how to operationalize it. Ecosystem plans are needed to formalize the process of operationalizing the EAFM by identifying and formalizing ecosystem goals and objectives, planning actions based on priorities, measuring performance of the whole fishery system, addressing trade-offs, and incorporating them in fisheries management. The Specific Contract N0 2 under the Framework Contract - EASME/EMFF/2016/008 provisions of Scientific Advice for Fisheries Beyond EU Waters has developed a pilot ecosystem plan for the tropical ecoregion of the Atlantic Ocean. In this document, we highlight the main potential benefits of developing ecosystem plans in ICCAT. Second, we briefly describe the main core elements developed in the pilot ecosystem plan for the Tropical ecoregion of the Atlantic Ocean. Third, we summarize our main thoughts and lessons learned in the development of this pilot ecosystem plan for one ecoregion within ICCAT. Last, we propose a list of actions, research activities and capacity building activities to foster the development, use and implementation of ecosystem plans in ICCAT.Versión del edito

Climate-driven impacts of exotic species on marine ecosystems

Aim Temperature is fundamental to the physiological and ecological performance of marine organisms, but its role in modulating the magnitude of ecological impacts by exotic species remains unresolved. Here, we examine the relationship between thermal regimes in the range of origin of marine exotic species and sites of measured impact, after human-induced introduction. We compare this relationship with the magnitude of impact exerted by exotic species on native ecosystems. Location Global. Time period 1977–2017 (meta-analysis). Major taxa studied Marine exotic species. Methods Quantitative impacts of exotic species in marine ecosystems were obtained from a global database. The native range of origin of exotic species was used to estimate the realized thermal niche for each species and compared with the latitude and climatic conditions in recipient sites of recorded impact of exotic species. The difference in median temperatures between recipient sites and the thermal range of origin (i.e., thermal midpoint anomaly) was compared with the magnitude of effect sizes by exotic species on native species, communities and ecosystems. Results Recorded impacts occurred predominantly within the thermal niche of origin of exotic species, albeit with a tendency toward higher latitudes and slightly cooler conditions. The severity of impacts by exotic species on abundance of native taxa displayed a hump-shaped relationship with temperature. Peak impacts were recorded in recipient sites that were 2.2°C cooler than the thermal midpoint of the range of origin of exotic species, and impacts decreased in magnitude toward higher and lower thermal anomalies. Main conclusions Our findings highlight how temperature and climatic context influence ecological impacts by exotic species in marine ecosystems and the implications for existing and novel species interactions under climate change.En prensa5,14

Selecting ecosystem indicators for fisheries targeting highly migratory species: An EU project to advance the operationalization of the EAFM in ICCAT and IOTC

Several international legal agreements and guidelines have set the minimum standards and key principles to guide the implementation of an ecosystem approach to fisheries management (EAFM). However, the implementation of an EAFM in tuna Regional Fisheries Management Organizations (RFMOs) has been patchy and lack a long-term plan, vision and guidance on how to operationalize it. The Specific Contract N0 2 “selecting ecosystem indicators for fisheries targeting highly migratory species-” (SC02 project) under the Framework Contract - EASME/ EMFF/2016/008 provisions of Scientific Advice for Fisheries Beyond EU Waters- addresses several scientific challenges and provides insights to support the implementation of an EAFM through collaboration and consultation with the International Commission for the Conservation of Atlantic Tunas (ICCAT) and the Indian Ocean Tuna Commission (IOTC). Specifically, this project first highlights properties of success and best practices from other regions of the world in operationalizing the ecosystem approach that potentially could be transferred to ICCAT and IOTC. Second, it delivered a list of potential ecosystem indicators of relevance to tuna RFMOs (ICCAT and IOTC) that are suitable to track the impacts of fisheries targeting tuna and tuna-like species on the broader pelagic ecosystem. Third, it designed a general framework based on a rule-based decision tree to provide guidance on how reference points could be set and used for diverse types of ecosystem indicators. Fourth, it proposed candidate ecoregions within the Atlantic and Indian Oceans which could be used to guide region-based ecosystem plans, assessments and research to ultimately provide better ecosystem-based advice to inform fisheries management. Fifth, it developed two pilot ecosystem plans for two case study regions, the tropical ecoregion within the ICCAT convention area, and the temperate ecoregion within the IOTC convention area. At this stage, these pilot ecosystem plans aim to create awareness about the need for ecosystem planning, start a discussion about the elements that need to be part of a planning process, and initiate a discussion in ICCAT and IOTC about the potential needs of ecosystem plans and their function. Finally, this project provided recommendations to foster the potential development, use, and implementation of ecosystem plans in ICCAT and IOTC

Nitrogen uptake and internal recycling in Zostera marina exposed to oyster farming: eelgrass potential as a natural biofilter

Oyster farming in estuaries and coastal lagoons frequently overlaps with the distribution of seagrass meadows, yet there are few studies on how this aquaculture practice affects seagrass physiology. We compared in situ nitrogen uptake and the productivity of Zostera marina shoots growing near off-bottom longlines and at a site not affected by oyster farming in San Quintin Bay, a coastal lagoon in Baja California, Mexico. We used benthic chambers to measure leaf NH4 (+) uptake capacities by pulse labeling with (NH4)-N-15 (+) and plant photosynthesis and respiration. The internal N-15 resorption/recycling was measured in shoots 2 weeks after incubations. The natural isotopic composition of eelgrass tissues and vegetative descriptors were also examined. Plants growing at the oyster farming site showed a higher leaf NH4 (+) uptake rate (33.1 mmol NH4 (+) m(-2) day(-1)) relative to those not exposed to oyster cultures (25.6 mmol NH4 (+) m(-2) day(-1)). We calculated that an eelgrass meadow of 15-16 ha (which represents only about 3-4 % of the subtidal eelgrass meadow cover in the western arm of the lagoon) can potentially incorporate the total amount of NH4 (+) excreted by oysters (similar to 5.2 x 10(6) mmol NH4 (+) day(-1)). This highlights the potential of eelgrass to act as a natural biofilter for the NH4 (+) produced by oyster farming. Shoots exposed to oysters were more efficient in re-utilizing the internal N-15 into the growth of new leaf tissues or to translocate it to belowground tissues. Photosynthetic rates were greater in shoots exposed to oysters, which is consistent with higher NH4 (+) uptake and less negative delta C-13 values. Vegetative production (shoot size, leaf growth) was also higher in these shoots. Aboveground/belowground biomass ratio was lower in eelgrass beds not directly influenced by oyster farms, likely related to the higher investment in belowground biomass to incorporate sedimentary nutrients

Arsenic concentrations in seagrass around the Mediterranean coast and seasonal variations

Arsenic’s occurrence in the environment could be due to human activities as well as to natural sources. In this study, Posidonia oceanica and Cymodocea nodosa are collected in 84 sites around the Mediterranean basin. In addition, both seagrass are collected monthly, in two sites (Calvi in Corsica and Salammbô in Tunisia). Arsenic concentrations in C. nodosa present seasonal variations in relation with spring phytoplankton blooms. For both species arsenic concentration is higher in the vicinity of geological sources (mining), lagoon outlets and industrial activities. Moreover, Mediterranean islands (Balearic, Sardinia, Corsica, Malta, Crete and Cyprus) and the Southern basin coastline exhibit lower concentrations in Arsenic than the rest of the Mediterranean basin. The wide spread distribution of these two species would encourage their use in a global monitoring network devoted to Arsenic contamination.peer-reviewe