Limited Seasonal Variation Research Articles

Comparatively poorer body condition of south-east Indian Ocean pygmy blue whales on their southern migration

The south-east Indian Ocean population of pygmy blue whales (Balaenoptera musculus brevicauda) forages in habitats between temperate foraging grounds off southern Australia and breeding grounds in Indonesian waters. With the opportunity to forage during migration, limited seasonal variation in body condition would be expected. However, increasing numbers of individuals in poor body condition with prominent spinal columns and other features of emaciation have been sighted during their southern migration. This study aimed to measure the morphology and body condition (relative body volume to body length) of pygmy blue whales during their northbound and southbound migration. Unmanned aerial vehicles were used to obtain images of 42 pygmy blue whales (one calf, five juveniles and 36 adults, including one lactating female) in 2021 and 2022. The body lengths ranged from 15.32 to 24.32 m, and the mean relative head length, length to blowhole, width of eyes, fluke width and length of peduncle were 21.8, 18.1, 12.8, 22.9 and 21.3% respectively. There was a significant decrease in body condition of 15.3% between north and southern migrating adult whales. Given the importance of body condition for reproductive success, understanding if this loss is due to natural seasonal variation, or habitat or prey disturbance from environmental environmental or anthropogenic sources, has implications for the future management of the species.

Offshore wind power around the Iberian Peninsula: variability, complementarity and added value for the power system

The advances in floating offshore wind energy are opening deep sea areas, like the coastal waters of Iberian Peninsula (IP), for the installation of wind farms. The integration of this new energy source in a semi-closed power system with an already high share of variable renewable energies would be facilitated if the potential contribution of offshore wind energy shows reduced variability and limited seasonal variations, as the power demand in IP shows two maxima in winter and summer. The aims of this study are the analysis of temporal variability and spatial complementarity of the potential installation sites, and the identification of an optimal combination of installation areas that minimizes the temporal variability of the aggregated offshore contribution. In order to better capture the marked mesoscale features of winds around the IP, wind data from a very high resolution reanalysis (COSMO-REA6) are used. The analysis considers allowed areas for installation, delimited by the maritime spatial planning. Northern coast areas are characterized by high capacity factors (CFs) and high seasonality, while the lower CFs at the western and southern coasts are compensated by a limited seasonality. Pairwise correlation between the potential areas shows outstanding results, with several negative correlation values within a synoptic scale region, in contrast to other mid-latitude regions like the North Sea or the Eastern USA coast. An optimal aggregation of areas includes at least one area at each of the four main Iberian coasts. A strong reduction of hourly variability is obtained through the resulting combinations, and the seasonality of the aggregated CF is clearly below the values for other offshore areas. Therefore, offshore wind energy can indeed offer an added value for the Iberian power system beyond the high resource amount, reducing the need for storage or backup plants.

Temporal activity patterns of bears, wolves and humans in the Cantabrian Mountains, northern Spain

Human-wildlife coexistence is important for a sustainable relationship between humans and the natural environment. However, human activities often act as a disturbance to wild animals, which may show behavioural shifts indicating human avoidance. For large carnivores, which are prone to conflict with many human interests, coexistence with humans can be particularly challenging. We used long-term camera trap data to evaluate seasonal and diel variations in activity of two large carnivores, the brown bear (Ursus arctos) and the grey wolf (Canis lupus), as well as humans in the Cantabrian Mountains, northern Spain. Brown bears were less active in winter than in summer; the opposite was observed for wolves, whereas there was limited seasonal variation in human activity. On a diel scale, both bears and wolves were mostly crepuscular during summer and had less distinct, but generally more nocturnal activity during winter. Humans were strictly diurnal during both seasons. We suggest that the diel activity of bears and wolves was partially caused by human avoidance, but that seasonal variations in both overall and diel activity were mainly caused by ecological and physiological factors. While we suggest that the observed similarity in diel activity of bears and wolves did not have caused strong competition between these two species, it may have influenced interactions with other predators and prey. Since such interactions are likely to be context dependent, we urge for further studies evaluating how humans influence the behaviour of large carnivores across different spatio-temporal scales.

Site‐specific space use and resource selection by Black Vultures (Coragyps atratus) in the southeastern USA

North American populations of Black Vultures Coragyps atratus have increased and expanded their distribution in the southern and eastern USA. In conjunction with these patterns has been a rise in human–vulture conflicts. To improve our understanding of space use patterns and better inform management, we evaluated the movements of Black Vultures (n = 23) in the southeastern USA using a long‐term GPS tracking database. Our specific objectives were to: (1) quantify home‐range sizes in relation to season and geographical study location and (2) examine within‐home‐range resource selection to identify landscape and anthropogenic factors influencing roost and diurnal space use. Home‐range sizes did not significantly differ between breeding and non‐breeding seasons. However, there were differences across geographical study locations, with the largest home‐ranges located in Florida. Similarly, there was limited seasonal variation in resource selection; however, use of anthropogenic features did vary by geographical study location. Overall Black Vultures avoided homogeneous landscapes regardless of season or activity and exhibited a strong selection for areas with increased landscape richness. Increased landscape richness, unlike homogeneous habitat, provides a diversity of resources for Black Vultures in a localized area, such as food, water, roosting and perch sites, and the creation of energy‐efficient flight opportunities. Contrasting with natural landscape feature selection, selection of anthropogenic features, such as landfill proximity and road density, was highly variable across individuals and study location. The high level of variation in selection for anthropogenic features provides further evidence of the propensity of Black Vultures to be flexible and opportunistic. The findings of this study stress the importance of using site‐specific studies effectively to understand and manage local vulture populations and mitigate associated human–vulture conflicts. Wildlife managers should exercise caution when implementing vulture management actions based on inferences from telemetry studies conducted in other geographical areas.

A seasonal climatology of the upper ocean pycnocline

Climatologies of the mixed layer depth (MLD) have been provided using several definitions based on temperature/density thresholds or hybrid approaches. The upper ocean pycnocline (UOP) that sits below the mixed layer base remains poorly characterized, though this transition layer is an ubiquitous feature of the ocean surface layer. Available hydrographic profiles provide near-global coverage of the world’s ocean and are used to build a seasonal climatology of UOP properties – intensity, depth, thickness – to characterize the spatial and seasonal variations of upper ocean stratification. The largest stratification values O(10−3s−2) are found in the intertropical band, where seasonal variations of the UOP are also very small. The deepest (> 200 m) and least stratified O(10−6s−2) UOPs are found in winter along the Antarctic Circumpolar Current (ACC) and at high latitudes of the North Atlantic. The UOP thickness has a median value of 23 m with limited seasonal and spatial variations; only a few regions have UOP thicknesses exceeding 35 m. The UOP properties allow the characterization of the upper ocean restratification that generally occurs in early spring and is generally associated with large variability. Depending on the region, this restratification may happen gradually as around the Rockall plateau or abruptly as in the Kuroshio Extension. The UOP is also likely to merge intermittently with the permanent pycnocline in winter. The upper edge of the UOP is eventually close to MLD estimates, except in a few notable regions such as in the Pacific Warm Pool where barrier layers are important, and during wintertime at high latitudes of the North Pacific.

The influence of vegetation water dynamics on the ASCAT backscatter–incidence angle relationship in the Amazon

Abstract. Microwave observations are sensitive to plant water content and could therefore provide essential information on biomass and plant water status in ecological and agricultural applications. The combined data record of the C-band scatterometers on the European Remote-Sensing Satellites (ERS)-1/2, the Metop (Meteorological Operational satellite) series, and the planned Metop Second Generation satellites will span over 40 years, which would provide a long-term perspective on the role of vegetation in the climate system. Recent research has indicated that the unique viewing geometry of the Advanced SCATterometer (ASCAT) could be exploited to observe vegetation water dynamics. The incidence angle dependence of backscatter can be described with a second order polynomial, the slope and curvature of which are related to vegetation. In a study limited to grasslands, seasonal cycles, spatial patterns, and interannual variability in the slope and curvature were found to vary among grassland types and were attributed to differences in moisture availability, growing season length and phenological changes. To exploit ASCAT slope and curvature for global vegetation monitoring, their dynamics over a wider range of vegetation types needs to be quantified and explained in terms of vegetation water dynamics. Here, we compare ASCAT data with meteorological data and GRACE equivalent water thickness (EWT) to explain the dynamics of ASCAT backscatter, slope, and curvature in terms of moisture availability and demand. We consider differences in the seasonal cycle, diurnal differences, and the response to the 2010 and 2015 droughts across ecoregions in the Amazon basin and surroundings. Results show that spatial and temporal patterns in backscatter reflect moisture availability indicated by GRACE EWT. Slope and curvature dynamics vary considerably among the ecoregions. The evergreen forests, often used as a calibration target, exhibit very stable behavior, even under drought conditions. The limited seasonal variation follows changes in the radiation cycle and may indicate phenological changes such as litterfall. In contrast, the diversity of land cover types within the Cerrado region results in considerable heterogeneity in terms of the seasonal cycle and the influence of drought on both slope and curvature. Seasonal flooding in forest and savanna areas also produced a distinctive signature in terms of the backscatter as a function of incidence angle. This improved understanding of the incidence angle behavior of backscatter increases our ability to interpret and make optimal use of the ASCAT data record and vegetation optical depth products for vegetation monitoring.

Stable isotopes reveal minimal spatial and temporal variation in diet of the wrymouth (Cryptacanthodes maculatus)

AbstractPredation by infaunal and epibenthic predators is often an important determinant of marine soft‐bottom community structure. The role of the predatory, benthic‐dwelling fish, the wrymouth (Cryptacanthodes maculatus), in the soft‐bottom food web has received little attention. The purpose of our study was to examine spatial and temporal variability in diet and trophic position of wrymouth at two lower intertidal sites in eastern Maine, USA. Wrymouth, their potential prey, and primary producers were collected in the spring and summer of 2013 in Machiasport and Beals, Maine. Stable isotope analysis was used to determine trophic position of the fish and its potential diet. Wrymouth δ13C signatures were influenced by location and ranged from −12.6‰ to −11.5‰, whereas δ15N signatures varied little (12.3‰–12.7‰) between locations or seasons. Wrymouth trophic position ranged from 3.02 to 3.48, indicating that they are tertiary consumers. The intertidal zone consisted of two distinct clusters of taxa, characterized by the presence of either macroalgae (mostly fucoids) or eelgrass (Zostera marina). Wrymouth diet consisted primarily of predatory polychaetes. Stable carbon and nitrogen isotope signatures varied across seasons and locations for multiple species, including our base species, Mya arenaria. Results suggest wrymouth are generalist feeders with limited seasonal and spatial variation in diet. Bottom‐up processes, however, are fundamentally different between the two study sites and influence their trophic structure. This result highlights the importance of collecting baseline data and evaluating trophic interactions at multiple spatial scales within small regional areas in coastal systems.

The Bacterial Community Diversity of Bathroom Hot Tap Water Was Significantly Lower Than That of Cold Tap and Shower Water.

Microbial drinking water quality in premise plumbing systems (PPSs) strongly affects public health. Bacterial community structure is the essential aspect of microbial water quality. Studies have elucidated the microbial community structure in cold tap water, while the microbial community structures in hot tap and shower water are poorly understood. We sampled cold tap, hot tap, and shower water from a simulated PPS monthly for 16 consecutive months and assessed the bacterial community structures in those samples via high-throughput sequencing of bacterial 16S rRNA genes. The total relative abundance of the top five most abundant phyla (Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, and Firmicutes) was greater than 90% among the 24 identified phyla. The most abundant families were Burkholderiaceae, Sphingomonadaceae, unclassified Alphaproteobacteria, unclassified Corynebacteriales, and Mycobacteriaceae. A multiple linear regression suggests that the bacterial community diversity increased with water temperature and the age of the simulated PPS, decreased with total chlorine residual concentration, and had a limited seasonal variation. The bacterial community in hot tap water had significantly lower Shannon and Inverse Simpson diversity indices (p < 0.05) and thus a much lower diversity than those in cold tap and shower water. The paradoxical results (i.e., diversity increased with water temperature, but hot tap water bacterial community was less diverse) were presumably because (1) other environmental factors made hot tap water bacterial community less diverse, (2) the diversity of bacterial communities in all types of water samples increased with water temperature, and (3) the first draw samples of hot tap water could have a comparable or even lower temperature than shower water samples and the second draw samples of cold tap water. In both a three-dimensional Non-metric multidimensional scaling ordination plot and a phylogenetic dendrogram, the samples of cold tap and shower water cluster and are separate from hot tap water samples (p < 0.05). In summary, the bacterial community in hot tap water in the simulated PPS had a distinct structure from and a much lower diversity than those in cold tap and shower water.

Spatiotemporal scales of larval dispersal and connectivity among oil and gas structures in the North Sea

The ecological role of offshore man-made infrastructure is of growing international interest. By 2030, globally more than 7500 oil and gas platforms could be removed, many of which now host mature hard substrate ecosystems formed by sessile benthic species including sponges, corals and mussels. We investigated the spatiotemporal scales of generalised species dispersal and connectivity among oil and gas structures in the North Sea using strategically designed 3D advective passive particle tracking experiments forced by high resolution (1.8 km, hourly) velocity fields including tide-, density- and wind-driven currents. Trajectories from 2 seasonal releases during mixed winter (February) and stratified summer (July) conditions of 2010 were analysed for a variety of pelagic larval durations (PLDs) spanning 2 to 28 d. Particles dispersed on average 32 km away from their origins after just 5 d, 67 km after 15 d, and 109 km after 28 d, with considerable spatial variability and limited seasonal variations. Short (2 d) PLDs generated highly connected networks over smaller spatial scales, while longer PLDs (28 d) generated less fragmented networks covering a much larger area but with fewer connections. Tidally driven dispersal was isolated using a new method based on the harmonic analysis of the velocity fields: the resulting maximum linear dispersal distances varied from ~4 km in the northern North Sea to ~8 km in the southern North Sea. The present study provides baseline spatiotemporal scales of dispersal and connectivity patterns and optimized relocatable methods to assess connectivity in tidally active shelf seas.

Elevation rather than season determines the assembly and co-occurrence patterns of soil bacterial communities in forest ecosystems of Mount Gongga.

Seasonal dynamics of soil microbial communities may influence ecosystem functions and services. However, few observations have been conducted on the dynamics of a bacterial community assembly across seasons in different elevations in mountain forest ecosystems. In this study, the diversity, compositions, community assembly processes, and co-occurrence interactions of soil bacterial communities were investigated using Illumina sequencing of 16S rRNA genes across different seasons during two consecutive years (2016 and 2017) at two elevational sites in Mount Gongga, China. These two sites included an evergreen broad-leaved forest (EBF, 2100 m a.s.l.) and a dark coniferous forest (DCF, 3000 m a.s.l.). The results showed that bacterial diversity and structure varied considerably between the two elevational sites with only limited seasonal variations. Interannuality had a significant effect on the diversity and structure of soil bacterial communities. The bacterial alpha diversity was significantly higher at site EBF(e.g., OTUs richness, 2207 ± 276) than at site DCF(e.g., OTUs richness, 1826 ± 315). Soil pH, temperature, elevation, and water content were identified as important factors shaping soil bacterial communities in the mountain forests. Bacterial community assembly was primarily governed by deterministic processes regardless of elevation and season. Deterministic processes were stronger at site DCF than at EBF. The soil bacterial community at site EBF harbored a more complex and connected network with less resistance to environmental changes. Overall, this study showed that seasonal dynamics of bacterial communities were much weaker than those along elevations, implying that a single-season survey on a bacterial community along an elevational gradient can represent overall changes in the bacterial community. KEY POINTS: • Seasonal dynamics of soil bacterial communities were studied in Mount Gongga. • The bacterial community was mainly affected by elevation rather than season. • Deterministic processes dominated bacterial community assembly. • The bacterial network was more complex but less stable at EBF than at DCF.

Air temperature lapse rates and cloud cover in a hyper-oceanic climate

AbstractAir temperature lapse rates vary geographically and temporally. Sub-Antarctic Macquarie Island provides an opportunity to compare lapse rates between windward and leeward slopes in a hyper-oceanic climate. Lapse rates were steep by global standards, typically close to the dry adiabatic lapse rate despite the near-constant high humidity. Limited diurnal and seasonal variation occurs in lapse rates on Macquarie Island. High variability of lapse rates on the eastern (lee) slope in summer months and in the midday hours appears to be driven by solar radiation. No diurnal or seasonal pattern was evident on the western slope. Development of orographic cloud is expected to modify lapse rates, given the theoretical shift between dry and saturated adiabatic lapse rates that occurs with condensation of water vapour. Cloud cover was frequent, with higher elevations being under cloud 50% of the time, with no seasonal variation. However, cloud base level did not explain variation in lapse rates. Low cloud is likely to be of ecological importance because it influences fog precipitation, solar radiation and evapotranspiration. Year-round dominance of westerly airflows and limited seasonal variation in air temperature and humidity explain the limited seasonal variation in cloud cover and lapse rates on Macquarie Island.

Techno-economic feasibility of fleets of far offshore hydrogen-producing wind energy converters

Innovative solutions need to be developed for harvesting wind energy far offshore. They necessarily involve on-board energy storage because grid-connection would be prohibitively expensive. Hydrogen is one of the most promising solutions. However, it is well-known that it is challenging to store and transport hydrogen which may have a critical impact on the delivered hydrogen cost.In this paper, it is shown that there are vast areas far offshore where wind power is both characterized by high winds and limited seasonal variations. Capturing a fraction of this energy could provide enough energy to cover the forecast global energy demand for 2050. Thus, scenarios are proposed for the exploitation of this resource by fleets of hydrogen-producing wind energy converters sailing autonomously. The scenarios include transportation and distribution of the produced hydrogen.The delivered hydrogen cost is estimated for the various scenarios in the short term and in the longer term. Cost estimates are derived using technical and economic data available in the literature and assumptions for the cost of electricity available on-board the wind energy converters. In the shorter term, delivered cost estimates are in the range 7.1–9.4 €/kg depending on the scenario and the delivery distance. They are based on the assumption of on-board electricity cost at 0.08€/kWh. In the longer term, assuming an on-board electricity cost at 0.04€.kWh, the cost estimates could reduce to 3.5 to 5.7 €/kg which would make the hydrogen competitive on several hydrogen markets without any support mechanism. For the hydrogen to be competitive on all hydrogen markets including the ones with the highest GHG emissions, a carbon tax of approximately 200 €/kg would be required.

Limited seasonal variation in food quality and foodweb structure in an Adirondack stream: insights from fatty acids

AbstractTogether terrestrial and aquatic resources fuel stream food webs. Past work suggests that both terrestrial and aquatic resources can vary in multiple metrics of food quality, such as elemental, macronutrient, and fatty acid (FA) composition, and that resource quality may vary seasonally in temperate systems. However, studies on FA composition in stream food webs, especially those quantifying seasonal patterns, remain scarce. We documented foodweb structure and examined FA composition as a metric of food quality in an Adirondack stream throughout the temperate growing season to understand from where stream consumers derived energy, how food quality varied among resources, and whether these patterns shifted seasonally. In spite of major seasonal shifts in environmental factors, such as light availability and temperature, we found limited seasonal variation in the FA composition of basal resources and macroinvertebrates. Instead, we found consistent differences in FA composition between aquatic and t...

Altitudinal, seasonal and interannual shifts in microbial communities and chemical composition of soil organic matter in Alpine forest soils

The study of soil microbial communities and chemical properties of soil organic matter (SOM) over altitudinal mountain gradients have been regarded as especially useful to better predict and help mitigate the effects of climate change. However, there is a lack of surveys considering altitudinal, seasonal and interannual variations at the same time. Here, we investigated four forest sites, along an altitude gradient (545–2000 m a.s.l.), in spring and autumn during two consecutive years (2014 and 2015) regarding i) soil temperature and physicochemical properties; ii) SOM chemical composition using pyrolysis; iii) soil microbial activity (basal respiration, potential enzyme activities, community level physiological profiles (CLPP)); iv) archaeal, bacterial and fungal abundance (qPCR, phospholipid fatty acid (PLFA) analysis, numbers of culturable heterotrophic bacteria); and v) microbial community structure (PLFA analysis). Sites at high altitudes (alpine, subalpine) showed lower mean, maximum and minimum soil temperatures respect to those at lower altitudes (montane, submontane) and were characterized by increased levels of SOM and nutrients, higher archaeal, bacterial and fungal abundance as well as higher microbial activities. Soils at the sites at higher altitudes presented a higher humification degree of SOM, as demonstrated by an enhanced content of aromatic compounds and fatty acids. The seasonal effect determined a rise in the content of SOM, some soil nutrients, basal respiration and microbial abundance in autumn respect to spring over the altitudinal gradient as well as a change in the structure of microbial community and SOM molecular composition. Interannuality had a significant effect on the relative abundance of various chemical groups of SOM compounds and on the ratios of microbial groups, and produced an increase in microbial abundance in the second study year, as a consequence of the increased soil maximum temperatures recorded in this year. CLPP showed to be site-specific with limited seasonal and interannual variations. Altitudinal, seasonal and interannual changes in chemical composition of SOM were explained by variations in PLFA-based microbial community structure as well as in the abundance of bacteria and fungi, which, in turn, were affected by climatic conditions.

The impact of seasonality on niche breadth, distribution range and species richness: a theoretical exploration of Janzen's hypothesis.

Being invoked as one of the candidate mechanisms for the latitudinal patterns in biodiversity, Janzen's hypothesis states that the limited seasonal temperature variation in the tropics generates greater temperature stratification across elevations, which makes tropical species adapted to narrower ranges of temperatures and have lower effective dispersal across elevations than species in temperate regions. Numerous empirical studies have documented latitudinal patterns in species elevational ranges and thermal niche breadths that are consistent with the hypothesis, but the theoretical underpinnings remain unclear. This study presents the first mathematical model to examine the evolutionary processes that could back up Janzen's hypothesis and assess the effectiveness of limited seasonal temperature variation to promote speciation along elevation in the tropics. Results suggest that trade-offs in thermal tolerances provide a mechanism for Janzen's hypothesis. Limited seasonal temperature variation promotes gradient speciation not due to the reduction in gene flow that is associated with narrow thermal niche, but due to the pleiotropic effects of more stable divergent selection of thermal tolerance on the evolution of reproductive incompatibility. The proposed modelling approach also provides a potential way to test a speciation model against genetic data.

Biological and environmental influences on parturition date and birth mass of a seasonal breeder.

Natal features (e.g. Julian birth date and birth mass) often have fitness consequences and can be influenced by endogenous responses by the mother to seasonal fluctuations in nutritional quality and photoperiodic cues. We sought to further understand the biological and environmental factors that influence the natal features of a polytocous species in an environment with constant nutritional resources and limited seasonal variation. During a 36-year study we assessed the influence of biological factors (maternal age and litter type [i.e., litter size and sexual composition]) and environmental factors (total precipitation and mean maximum temperature during months encompassing conception, the last trimester of gestation, and the entire length of gestation) on Julian birth date and birth mass using linear-mixed effects models. Linear and quadratic functions of maternal age influenced both natal features with earliest Julian birth dates and heaviest birth masses occurring at prime-age and older individuals, which ranged from 5–9 years of age. Litter type influenced Julian birth date and birth mass. Interestingly, environmental factors affected Julian birth date and birth mass even though mothers were continuously allowed access to a high-quality diet. Random effects revealed considerable variation among mothers and years. This study demonstrates that, in long-lived polytocous species, environmental factors may have a greater influence on natal features than previously supposed and the influence from biological factors is also complex. The documented responses to environmental influences provide unique insights into how mammalian seasonal reproductive dynamics may respond to current changes in climate.

Algal massive growth in relation to water quality and salinity at Damietta, north of Egypt

Objective: To relate the proliferation and dominance of certain algal species at the Damietta and its relation to water quality. Methods: Water and algal biomass were bimonthly sampled from five selected sites at Damietta Province, Egypt during 2012. Algae were identified and quantified. Waters, algae and sediment were analyzed. Results: The physicochemical properties of water showed limited seasonal but substantial local variation. The high levels of nitrogen and phosphorus and turbidity of water pointed to marked eutrophication, which could enhance massive algal growth. The temporal fluctuation in temperature, exposure to industrial and domestic sewage and salinity results in succession between blooming algal species. Spirulina platensis and Chlorella vulgaris alternated in a moderately saline water and Oscillatoria agardhii and Mougeotia scalaris in a fresh water body during summer and winter respectively. Likewise, Microcystis aureginosa and Ulva lactuca alternated in a moderately saline site during autumn and summer respectively. Cladophora albida dominated a fish pond of brackish water and Dunaliella salina dominated the most saline water over the whole period of study. Conclusions: Growth of the predominant algal species is correlated to water quality. These species are of considerable nutritive value, with moderate contents of protein, carbohydrate, macronutrients and micronutrients, which evaluates them for usage as food (green and macroalgae), fodder or bio-fertilizer (cyanophytes). Peer reviewer

Seasonal variation of Fatty acids and stable carbon isotopes in sponges as indicators for nutrition: biomarkers in sponges identified.

To get a better understanding of sponge feeding biology and efficiencies, the fatty acid (FA) composition and (13)C natural abundance of sponges and of suspended particulate matter (SPM) from surrounding seawater was studied in different seasons at three locations. Haliclona oculata and Haliclona xena from the Oosterschelde, the Netherlands, Halichondria panicea and H. xena from Lake Veere, the Netherlands, and Aplysina aerophoba and Dysidea avara from the Mediterranean, Spain, were studied. Several FA biomarkers for different algal groups, bacteria and sponge biomass were identified in all sponges. The FA concentration variation in sponges was related to changes in fatty acid concentration in SPM. Stable carbon isotopic ratios (δ(13)C) in sponge specific FAs showed very limited seasonal variation at all sites. Algal FAs in sponges were mainly acquired from the SPM through active filtration in all seasons. At the two sites in the Netherlands only in May (spring), the sponge specific FAs had similar δ(13)C ratios as algal FAs, suggesting that sponges were mainly growing during spring and probably summer. During autumn and winter, they were still actively filtering, but the food collected during this period had little effect on sponge δ(13)C values suggesting limited incorporation of filtered material into the sponge body. The sponge A. aerophoba relied mostly on the symbiotic bacteria. In conclusion, fatty acid composition in combination with stable carbon isotope analysis can be used to analyze the food source of sponges.

Modeling growing season phenology in North American forests using seasonal mean vegetation indices from MODIS

The phenology of vegetation exerts an important control over the terrestrial ecosystem carbon (C) cycle. Remote sensing of key phenological phases in forests (e.g., the spring onset and autumn end of growing season) remains challenging due to noise in time series and the limited seasonal variation of canopy greenness in evergreen forests. Using 94 site-years of C flux data from four deciduous broadleaf forests (DBF) and six evergreen needleleaf forests (ENF) in North America, we examine whether growing season phenology can be remotely sensed from mean vegetation indices (VIs) derived from spring (Apr.–May) and autumn (Sep.–Nov) observations. Five VIs were used based on Moderate Resolution Imaging Spectroradiometer (MODIS) data, including the normalized difference vegetation index (NDVI), the land surface water index (LSWI), the enhanced vegetation index (EVI), the wide dynamic range vegetation index (WDRVI) and the optimized soil-adjusted vegetation index (OSAVI). Our results show that growing season transitions can be inferred from mean seasonal VIs, though the different VIs varied in their predictive strength across sites and plant functional types. Widely used NDVI and EVI exhibited limited potential in tracking growing season phenology of ENF ecosystems, while indices sensitive to water (i.e., LSWI) or less influenced by soil (i.e., OSAVI) may have unrevealed powers in indicating phenological transitions. OSAVI was shown to be a strong predictor of the end of the growing season in ENF ecosystems, suggesting that this VI may offer a new strategy for modeling the phenology of ENF sites. We conclude that combinations of multiple indices may improve the remote sensing of land surface phenology, as evidenced by the good agreement between modeled and observed growing season transitions and its length in our evaluation.

Microalgae as a Potential New Generation of Material for Various Innovative Products

Nowadays, great interest has been developed in the isolation of novel bioactive compounds from the marine world which represents the half of the global biodiversity and an untapped reservoir of natural ingredients. Among these ingredients microalgae can play a key role [1,2]. They can biosynthesize many valuable substances with potential applications in the food, feed, pharmaceutical, cosmetic and chemical industry. But the impact of microalgae on the human society is not limited only to their useful products, because of their crucial role on the biosphere through photosynthesis. Microalgae are primitive, aquatic and photosynthetic microorganisms which appeared on earth about 3.5 billion years ago. They have unicellular or simple multicellular structure and size between 0.2 to 2 nm. Moreover, they have some advantages over terrestrial plants such as higher productivity due to their reproducing by simple division one or two times per day, limited seasonal variation and no lack of raw material. It is estimated that more than 30,000 species of microalgae exist, but only a few are safe and are cultivated in industrial quantities [3,4]. Microalgae that are already commercialized and are used in biotechnology belong to the green algae (e.g. the species Chlorella, Dunaliela, Haematococcus, Tetraselmis, Isochrysis) and cyanobacteria – the intermediate blue-green colored species between plants and bacteria (e.g. Spirulina (Arthrospira), Aphanizomenon flosaquae) [3,5,6]. Microalgae can survive under harsh conditions and environmental stressors such as high or low temperature, anaerobiosis, high salinity, photo-oxidation, high osmotic pressure and ultra-violet radiation, so they can greatly modify their chemical composition [2,7]. As a result of the rapid adaptation of algae to the new environmental conditions, they synthesize and produce a great variety of secondary metabolites having structure that cannot be found in other organisms [8]. As a results marine microalgae, due to their abundant availability in the marine ecosystem are an excellent source of valuable compounds such as polyunsaturated fatty acids, proteins, tocopherols and sterols, vitamins and minerals, antioxidants and pigments [7,9]. Consequently, nowadays there are several different applications for microalgae [2,3,10-12]. They could be used in: