Satellite remote sensing reveals a positive impact of living oyster reefs on microalgal biofilm development

Satellite remote sensing (RS) is routinely used for the large-scale monitoring of microphytobenthos (MPB) biomass in intertidal mudflats and has greatly improved our knowledge of MPB spatio-temporal variability and its potential drivers. Processes operating on smaller scales however, such as the impact of benthic macrofauna on MPB development, to date remain underinvestigated. In this study, we analysed the influence of wild Crassostrea gigas oyster reefs on MPB biofilm development using multispectral RS. A 30-year time series (1985-2015) combining high-resolution (30 m) Landsat and SPOT data was built in order to explore the relationship between C. gigas reefs and MPB spatial distribution and seasonal dynamics, using the normalized difference vegetation index (NDVI). Emphasis was placed on the analysis of a before-after control-impact (BACI) experiment designed to assess the effect of oyster killing on the surrounding MPB biofilms. Our RS data reveal that the presence of oyster reefs positively affects MPB biofilm development. Analysis of the historical time series first showed the presence of persistent, highly concentrated MPB patches around oyster reefs. This observation was supported by the BACI experiment which showed that killing the oysters (while leaving the physical reef structure, i.e. oyster shells, intact) negatively affected both MPB biofilm biomass and spatial stability around the reef. As such, our results are consistent with the hypothesis of nutrient input as an explanation for the MPB growth-promoting effect of oysters, whereby organic and inorganic matter released through oyster excretion and biodeposition stimulates MPB biomass accumulation. MPB also showed marked seasonal variations in biomass and patch shape, size and degree of aggregation around the oyster reefs. Seasonal variations in biomass, with higher NDVI during spring and autumn, were consistent with those observed on broader scales in other European mudflats. Our study provides the first multi-sensor RS satellite evidence of the promoting and structuring effect of oyster reefs on MPB biofilms

Global ocean spatial suitability for macroalgae offshore cultivation and sinking

Macroalgae offshore cultivation and sinking is considered a potentially practical approach for ocean-based carbon dioxide removal. However, several considerations need to be resolved to assess the effectiveness and sustainability of this approach. Currently, several studies focus on the area required for climate-relevant carbon sequestration through macroalgae cultivation and sinking without considering realistic, global spatial limitations. This study uses a spatially-explicit suitability assessment model for optimised open-ocean afforestation and sinking site designation. By applying specific maritime, ecological and industrial constraints, two maps are produced: a) suitable areas for macroalgae offshore cultivation and sinking, and b) suitable areas for macroalgae sinking only (for sequestration purposes). These data provide a more realistic approach to quantifying the ocean surface (including the corresponding depths) required for macroalgae offshore cultivation and sinking within a spatially sustainable framework. The resulting maps estimate the respective suitability areas within the EEZs of the world countries. A total area suitable for macroalgae offshore cultivation and sinking is calculated at 10.8M km2, whereas sinking-only areas account for 32.8M km2 of the offshore ocean. The implications of spatial suitability patterns at global and national levels are discussed. We suggest that the concept of ‘grow nearshore, sink offshore’ should be explored as an alternative to offshore cultivation

Assessment and Prediction of Evapotranspiration Based on Scintillometry and Meteorological Datasets

Two methods are used for estimating the evapotranspiration (ET) rate: scintillometry and meteorological measurements using the FAO-PM56 model with the reference evapotranspiration for the crop (ETO) and the specific coefficient (Kc) for corn at its stage development. Measurements were done on a field with homogeneous corn crop at the stage of 3 months before the final harvest (65 % of maximum plant growth). The two methods are compared with environmental parameters to determine the most influential on the final result of ET

Sentinel-2 remote sensing of Zostera noltei-dominated intertidal seagrass meadows

Accurate habitat mapping methods are urgently required for the monitoring, conservation, and management of blue carbon ecosystems and their associated services. This study focuses on exposed intertidal seagrass meadows, which play a major role in the functioning of nearshore ecosystems. Using Sentinel-2 (S2) data, we demonstrate that satellite remote sensing can be used to map seagrass percent cover (SPC) and leaf biomass (SB), and to characterize its seasonal dynamics. In situ radiometric and biological data were acquired from three intertidal meadows of Zostera noltei along the European Atlantic coast in the summers of 2018 and 2019. This information allowed algorithms to estimate SPC and SB from a vegetation index to be developed and assessed. Importantly, a single SPC algorithm could consistently be used to study Z. noltei-dominated meadows at several sites along the European Atlantic coast. To analyze the seagrass seasonal cycle and to select images corresponding to its maximal development, a two-year S2 dataset was acquired for a French study site in Bourgneuf Bay. The po-tential of S2 to characterize the Z. noltei seasonal cycle was demonstrated for exposed intertidal meadows. The SPC map that best represented seagrass growth annual maximum was validated using in situ measurements, resulting in a root mean square difference of 14%. The SPC and SB maps displayed a patchy distribution, influenced by emersion time, mudflat topology, and seagrass growth pattern. The ability of S2 to measure the surface area of different classes of seagrass cover was investigated, and surface metrics based on seagrass areas with SPC >= 50% and SPC >= 80% were computed to estimate the interannual variation in the areal extent of the meadow. Due to the high spatial resolution (pixel size of 10 m), frequent revisit time (<= 5 days), and long-term objective of the S2 mission, S2-derived seagrass time-series are expected to contribute to current coastal ecosystem management, such as the European Water Framework Directive, but to also guide future adaptation plans to face global change in coastal areas. Finally, recommendations for future intertidal seagrass studies are proposed

Remote Sensing-Driven Pacific Oyster (Crassostrea gigas) Growth Modeling to Inform Offshore Aquaculture Site Selection

Aquaculture increasingly contributes to global seafood production, requiring new farm sites for continued growth. In France, oyster cultivation has conventionally taken place in the intertidal zone, where there is little or no further room for expansion. Despite interest in moving production further offshore, more information is needed regarding the biological potential for offshore oyster growth, including its spatial and temporal variability. This study shows the use of remotely-sensed chlorophyll-a and total suspended matter concentrations retrieved from the Medium Resolution Imaging Spectrometer (MERIS), and sea surface temperature from the Advanced Very High Resolution Radiometer (AVHRR), all validated using in situ matchup measurements, as input to run a Dynamic Energy Budget (DEB) Pacific oyster growth model for a study site along the French Atlantic coast (Bourgneuf Bay, France). Resulting oyster growth maps were calibrated and validated using in situ measurements of total oyster weight made throughout two growing seasons, from the intertidal zone, where cultivation currently takes place, and from experimental offshore sites, for both spat (R2 = 0.91; RMSE = 1.60 g) and adults (R2 = 0.95; RMSE = 4.34 g). Oyster growth time series are further digested into industry-relevant indicators, such as time to achieve market weight and quality index, elaborated in consultation with local producers and industry professionals, and which are also mapped. Offshore growth is found to be feasible and to be as much as two times faster than in the intertidal zone (p < 0.001). However, the potential for growth is also revealed to be highly variable across the investigated area. Mapping reveals a clear spatial gradient in production potential in the offshore environment, with the northeastern segment of the bay far better suited than the southwestern. Results also highlight the added value of spatiotemporal data, such as satellite image time series, to drive modeling in support of marine spatial planning. The current work demonstrates the feasibility and benefit of such a coupled remote sensing modeling approach within a shellfish farming context, responding to real and current interests of oyster producers

In vivo estimation of pigment composition and optical absorption cross-sectionby spectroradiometry in four aquatic photosynthetic micro-organisms

International audienceThe objective of the present study was to estimate in vivo pigment composition and to retrieve absorption cross-section values, a∗, of photosynthetic micro-organisms using a non-invasive technique of reflectance spectrometry. To test the methodology, organisms from different taxonomical groups and different pigment composition were used (Spirulina platensis a Cyanophyta, Porphyridium cruentum a Rhodophyta, Dunaliella tertiolecta a Chlorophyta and Entomoneis paludosa a Bacillariophyta) and photoacclimated to two different irradiance levels: 25 μmol photon m−2 s−1 (Low Light, LL) and 500 μmol photon m−2 s−1 (High Light, HL). Second derivative spectra from reflectance were used to identify pigment in vivo absorption bands that were linked to specific pigments detected by high performance liquid chromatography. Whereas some absorption bands such as those induced by Chlorophyll (Chl) a (416, 440, 625 and around 675 nm) were ubiquous, others were taxonomically specific (e.g. 636 nm for Chl c in E. paludosa) and/or photo-physiological dependent (e.g. 489 nm for zeaxanthin in the HL-acclimated S. platensis). The optical absorption cross-section, a∗, was retrieved from reflectance data using a radiative transfer model previously developed for microphytobenthos. Despite the cellular Chl a decrease observed from LL to HL (up to 88% for S. platensis), the a∗ increased, except for P. cruentum. This was attributed to a ‘package effect’ and to a greater absorption by photoprotective carotenoids that did not contribute to the energy transfer to the core Chl a

Nemendur af erlendum uppruna: Reynsla foreldra og kennara af námi og kennslu

Nemendum af erlendum uppruna hefur fjölgað mikið í íslenskum skólum. Það kallar á að skólar bregðist við námsþörfum þessa nemendahóps. Markmið þessarar greinar er að fjalla um reynslu kennara og foreldra af menntun nemenda af erlendum uppruna. Í eigindlegri rannsókn voru tekin viðtöl við þrjátíu og átta grunnskólakennara um reynslu þeirra af því að kenna nemendum af erlendum uppruna og helstu áskoranir sem því fylgja. Einnig voru tekin viðtöl við tíu erlenda foreldra um reynslu þeirra af íslenskum skólum. Niðurstöður sýna að kennarar telja sig ekki vera nægilega vel studda til þess að skilja og takast á við námsþarfir nemendanna. Upplifun foreldra litast af hugmyndum þeirra um skólann sem hinn hefðbundna stað fyrir nám og íslenska skólakerfið ögrar þessum skilningi þeirra. Skortur er á samvinnu og samskiptum milli forelda og kennara. Í niðurlagi er lagt til að skólar stuðli að markvissari umræðu um þarfir nemenda og væntingar foreldra svo að efla megi og bæta menntun nemenda af erlendum uppruna.There is a constantly growing number of students of foreign origin in Icelandic education. These changes require schools and teachers to respond to the educational needs these students may have. The results of Icelandic research on multicultural education have, in the main, suggested that the Icelandic school system is failing in its efforts to educate children of foreign origin. Current legislation on schools in Iceland strongly emphasises equality, and schools are expected to suit their operation as closely as possible to the situation and needs of the students; thus, in a broad sense, supporting every student’s development, welfare and education. This emphasis is reiterated, at each stage, in the Icelandic National Curriculum Guide for Compulsory Schools (Mennta- og menningarmálaráðuneyti, 2012b) Icelandic education policy is based on the ideology of the inclusive school which focuses on meeting students’ diverse needs, whether those be academic or social; thus the operation of the school attempts to ensure that students are given equal or equivalent educational opportunities The policy also emphasizes the diversity of the student group, leading to their varied needs. Despite the attempt to recognize diversity within the Icelandic school system, for example in legislation and curricula, the multicultural aspect of the education policy has not received much attention. In academic discourse on the inclusive school and multicultural education, research, both in Iceland and abroad shows that impediments to real change towards multicultural practices are not least to be found in attitudes to students who need additional assistance in their studies and in parents’ and teachers’ expectations towards them. When initiating and developing a multicultural, inclusive school operation, respect for families and their diverse backgrounds has a crucial role. School staff have to be prepared to work with parents of varied origin and to demonstrate an understanding of their circumstances and world view. The objective of this article is to examine the experience of teachers and parents of students with immigrant background with regard to their education. Answers are sought to the following research questions: How do teachers approach the education of children of foreign origin; and how do parents from abroad perceive and experience their children’s education? Focus group interviews were conducted with thirty eight teachers from six primary schools discussing their experience of teaching students of a foreign background and the main challenges they faced in this context. Individual interviews were also conducted with ten parents from abroad in relation to their perception of Icelandic schools and their children’s education, The research revealed that the teachers feel they are not sufficiently trained and prepared to tackle the demanding tasks of multicultural teaching. Furthermore, the support and encouragement needed to stimulate teachers’ interest and ambition to take on this kind of teaching appeared to be lacking. Due to insufficient communication between schools and homes, many parents are unfamiliar with the aims and methods of the Icelandic school system. This has caused foreign parents to distrust the school and prevented them from being able to keep close track of their children’s studies. The parents’ attitudes are coloured by their notions of the school as a traditional venue of study and the Icelandic school system challenges their traditional ideas in this respect. Cooperation and communication between parents and teachers is also lacking. The article suggests that these shortcomings should be dealt with and discussion and dialogue should be encouraged between the parties concerned, focusing on the students’ needs and parental expectations, with the aim of supporting and improving the education of students of foreign origin.Peer reviewe

Pacific oyster (Crassostrea gigas) growth modelling and indicators for offshore aquaculture in Europe under climate change uncertainty

Aquaculture development in Europe, while critical to the European Union (EU) Blue Growth strategy, has stagnated over the past decades due largely to high competition for space in the nearshore coastal zone among potential uses and the lack of clear priorities, policy, and planning at EU and national scales. Broad Marine Spatial Planning, including the designation of Allocated Zones for Aquaculture, requires spatial data at the corresponding broad spatial scale, which has not been readily available, as well as model projections to assess potential impacts of climate change. Here, daily chlorophyll-a, water temperature, salinity, and current speed outputs from a marine ecosystem model encompassing the coastal North East Atlantic, the North Sea, and the Mediterranean Sea (the pan-European POLCOMS-ERSEM model configuration) are used to drive a Dynamic Energy Budget growth model of Pacific oyster (Crassostrea gigas). Areas broadly suitable for growth were identified using threshold tolerance range masking applied using the model variables mentioned above, as well as bathymetry data. Oyster growth time series were transformed into simplified indicators that are meaningful to the industry (e.g., time to market weight) and mapped. In addition to early-century indicator maps, modelling and mapping were also carried out for two contrasting late-century climate change projections, following representative concentration pathways 4.5 and 8.5. Areas found to have good oyster growth potential now and into the future were further assessed in terms of their climate robustness (i.e., where oyster growth predictions are comparable between different future climate scenarios). Several areas within Europe were highlighted as priority areas for the development of offshore Pacific oyster cultivation, including coastal waters along the French Atlantic, the southern North Sea, and western Scotland and Ireland. A large potential growth hot spot was also identified along northwestern Africa, associated with a cool, productive upwelling coastal zone. The framework proposed here offers a flexible approach to include a large range of ecological input data, climate and ecosystem model scenarios, aquaculture-related models, species of interest, indicator types, and tolerance thresholds. Such information is suggested to be included in more extensive spatial assessments and planning, along with further socioeconomic and environmental data