Sediment Granulometry Research Articles

Trophodynamics of estuarine intertidal harpacticoid copepods based on stable isotope composition and fatty acid profiles

Trophic interactions at the basis of food webs, for instance between meiofauna, primary producers and bacteria, are key drivers of benthic energy fluxes. Yet both qualitative and quantitative information about meiofaunal resource utilization under in situ conditions is scant. By means of natural stable isotope ratios of carbon and nitrogen and of fatty acid (FA) profiles, we examined the variability of in situ resource utilization of a range of harpacticoid copepod species from 5 stations in an estuarine intertidal area. These stations, located in different habitats, differed in sediment granulometry, resource availability, presence/absence of vegetation and other environmental variables, as well as in copepod species composition. Our goal was to describe interspecific differences among harpacticoid species, as well as spatio-temporal variability within species. Despite differences in resource availability between habitats, delta C-13 data clearly point at microphytobenthos (MPB) as the major carbon source to the harpacticoid assemblages at all 5 stations. Small differences in carbon isotopic ratios between co-occurring species indicate some degree of resource differentiation, whereas both the delta N-15 and FA composition suggest that several harpacticoid species obtain MPB carbon indirectly, perhaps through feeding on bacteria or ciliates. For a limited number of species, such as Paraleptastacus spinicauda, clear dietary contributions of suspended particulate matter and bacteria were found, and MPB appeared to have only a small or no contribution. Even in vegetated salt-marsh stations, Spartina anglica detritus did not appear to contribute to copepod diets. The delta C-13 of Cletodidae were highly depleted, reflecting a contribution of methane-derived carbon.

Impacts of dredged-material disposal on the coastal soft-bottom macrofauna, Saronikos Gulf, Greece

Dredged sediments derived by the low course and estuary of the metropolitan river of Athens (Kifissos River) were dumped every day for 21months to an open-sea site in the Saronikos Gulf. The spoil-ground and surrounding area was monitored prior, during and post to dumping for 24months, over 6-month intervals. Dumping significantly changed the granulometry of the pre-existing superficial sediments to finer-grained only in the spoil ground and increased the sediment contamination load (aliphatic, polycyclic aromatic hydrocarbons and heavy metals) throughout the study area. Microtox® SPT showed that sediment toxicity levels were high at almost all sampling stations. During dumping, burial of natural soft-bottom habitats degraded severely the communities of the spoil-ground resulting in an almost azoic state, as well as significantly declined the species number and abundance of benthic communities in locations up to 3.2km away from the spoil-ground, due to dispersion of the spoil and smothering. Benthic indices on the surrounding sites were significantly correlated with hydrocarbon concentrations and sediment toxicity levels. Post to dumping, the macrofauna communities of the spoil-ground were still significantly degraded, but the surrounding areas showed patterns of recovery. However, the high concentrations of aliphatic, polycyclic aromatic hydrocarbons and levels of toxicity persisted in the sediments after the ceasing of dumping operations in the study area, implying the ecological hazard imposed on the area.

Effects of open‐cast sulphur mining on sediment transfers and toxification of riparian forests

The spoil heaps of the sulphur mines of the egoiul omânesc volcanic cone are intensely reworked by mass movement processes which not only lead to severe sedimentation in downstream rivers, but also to the toxification of riparian orway spruce (icea abies (.) arst.) forests. Along the lateral borders of the Dumitrelul retention basin, recent sedimentation has covered . abies trees with up to 160 cm of toxic, sulphur‐rich material originating from the spoil heaps deposits. This study documents the deposition of toxic sediments and illustrates the effects that these sulphur‐rich sediments have on tree growth. The results show that trees affected by sedimentation reacted with severe growth suppression and the formation of tangential rows of traumatic resin ducts, and that the intensity and persistence of growth anomalies in trees are positively correlated with local depths and granulometry of sediments.

Amphipods from marine cave sediments of the southern Iberian Peninsula: diversity and ecological distribution

Summary: The present study explores the amphipod assemblages of six marine caves on the Mediterranean coast of southern Spain. Replicate samples were taken both inside and outside each marine cave in order to characterize the amphipod fauna and the physicochemical properties of the sediment. As a result, 44 amphipods species were identified. The high number of species found in a relatively limited area highlighted the richness of the Alboran Sea fauna, which is mainly due to the mixture of species from different biogeographic areas. Harpinia genus was the dominant amphipod taxa inside marine caves and Perioculodes longimanus was also very abundant in the caverns. On the other hand, external communities were dominated by Siphonoecetes sabatieri, Metaphoxus fultoni and Photis longipes. There was a high degree of variability in both the internal and the external stations. Only the external station situated at low-medium depth showed a relatively homogeneous amphipod assemblage. The structure and behaviour of soft-bottom communities inside marine caves is difficult to predict because their environmental conditions depend on a particular combination of factors such as topography, depth and orientation. Therefore, no constant patterns were observed for species richness, Shannon diversity and abundance of amphipods in marine caves in comparison with open habitats. According to canonical correspondence analysis, sediment granulometry, organic matter and nitrogen concentration were the parameters that best explained the distribution of amphipods. Species were also classified by their tolerance to environmental pollution according to criteria followed by the Azti Marine Biotic Index and the BENTIX index. The great abundance of sensitive species at both the internal and external stations indicates the good ecological quality of the soft bottom studied. However, the suitability of biotic indices in marine caves should be tested in future studies.

Northern New Zealand rhodoliths: assessing faunal and floral diversity in physically contrasting beds

Rhodolith beds are recognised internationally as unique ecosystems, harbouring a high diversity and abundance of marine biota. Beds typically occur in environments of moderate exposure and coarse sandy sediments, in which individual rhodoliths are not moved away from the beds, and do not get buried by fine sediments. For the first time in New Zealand, we have physically and biologically characterised selected rhodolith beds in order to document the marine biota within and beneath them. Three beds at two locations in the Bay of Islands, northern New Zealand, were sampled in February and September 2010; two beds were located in a typical rhodolith habitat (a sandy channel), and one in an atypical habitat (a muddy bay). In each bed, rhodolith species and abundance were analysed along with environmental characteristics (sediment granulometry, light environment, temperature, current speed and direction). Characterisation of biological diversity associated with the rhodolith beds included assessment of macroalgae, invertebrates (surface and subsurface) and fish. Sampling within the beds produced a total of 238 taxa: 197 invertebrates, 37 algal and four fish taxa, indicating that a high diversity of biota occur within these northern New Zealand rhodolith beds. We found significant differences in the abundance, taxon richness, and community structure of the biota among rhodolith beds, and surprisingly, the highest abundance and taxon richness occurred in a bed in a highly sedimented environment. In addition, two adjacent and physically similar beds were significantly different from each other in terms of community structure. This finding points to the importance of sampling individual rhodolith beds and suggests that it would be risky to extrapolate findings to other beds, even those in close proximity.

Does water level affect benthic macro-invertebrates of a marginal lake in a tropical river-reservoir transition zone?

Benthic macro-invertebrates are important components of freshwater ecosystems which are involved in ecological processes such as energy transfer between detritus and consumers and organic matter recycling. The aim of this work was to investigate the variation in organism richness, diversity and density of benthic fauna during the annual cycle in Camargo Lake, a lake marginal to Paranapanema River, southeast Brazil. The correlation of environmental factors with community attributes of the macro-benthic fauna was assessed. Since Camargo Lake is connected to the river, we tested the hypothesis that water level variation is the main regulating factor of environmental variables and of the composition and abundance of benthic macro-invertebrates. The results indicated that lake depth varied with rainfall, being the highest at the end of the rising water period and the lowest at the beginning of this period. The sediment granulometry was more heterogeneous at the bottom of the lake by the end of the high water period. The benthic macro-invertebrate fauna was composed by 15 taxa. The Diptera order was represented by seven taxa and had greater richness in relation to other taxa. This group was responsible for 60% of the total abundance of organisms, followed by Ephemeroptera (22%) and Anellida (16%). Significant differences were observed over time in total richness and, in density of Narapa bonettoi, Chaoborus, Ablabesmyia gr. annulata, Chironomus gigas, Larsia fittkau, and Procladius sp. 2. Total taxa richness correlated negatively with water pH, transparency, conductivity, and bottom water oxygen. Higher positive correlations were found between the densities of some taxa and bottom water oxygen, conductivity and very fine sand, silt + clay of sediment, while negative correlations were recorded with organic matter, and fine, medium and coarse sand, bottom water temperature, mean temperature and rainfall. The significant temporal difference in water level was associated with changes in abiotic factors and macro-invertebrate community attributes.

Land-use effects on river habitat quality and sediment granulometry along a 4th-order tropical river

Land-use change, i.e., the transformation of natural land into agricultural and urban area is among the most important human impacts on habitat quality and species diversity. In this study, we investigated the effects of land use on river habitat quality and sediment granulometry in a larger tropical river, affected by urbanization and agricultural land use. We selected 15 representative sampling reaches in the Rio das Mortes basin, 12 of them along the main river from its headwater to its mouth, and 3 in major tributaries. A habitat survey was conducted in these reaches in the dry season 2010 and sediment samples were taken for granulometry analyses. Sub-basin land cover of reaches was dominated by natural vegetation (41.6 to 60.2% of total land cover), followed by agricultural land cover (38.4% to 56.9%) and urban land cover (1.4% to 5.6%). Sediments were dominated by poorly to moderately sorted silts to sands, little conducive to diverse biological communities. According to the river habitat survey, all investigated river reaches exhibited moderately to totally disturbed habitat integrity, due to diverse and often co-occurring human impacts, such as riparian deforestation, water abstraction, sand and gravel extraction, and margin erosion. Only one of the investigated sampling reaches exhibited the minimum riparian forest corridor width demanded by the Brazilian Forest Code. Our results indicated that river habitat and sediment quality mainly depended on conditions in the direct vicinity of river reaches. Accordingly, initial cost-effective restoration of aquatic habitats could be achieved by relatively simple channel restoration measures and the protection of the riparian corridor in the investigated tropical river.

Historical changes in trace metals and hydrocarbons in nearshore sediments, Alaskan Beaufort Sea, prior and subsequent to petroleum-related industrial development: Part II. Hydrocarbons

Composition and concentration of hydrocarbons (normal and isoprenoid alkanes, triterpenoids, steranes, and PAHs) in nearshore surface sediments from Elson Lagoon (EL), Colville Delta–Prudhoe Bay (CDPB) and Beaufort Lagoon (BL), Alaskan Beaufort Sea, were assessed for spatio-temporal variability. Principal component analysis of the molecules/biomarkers concentrations delineated CDPB and BL samples into two groups, and cluster analysis identified three station groups in CDPB. Overall there was no geographic distribution pattern in the groups. The diversities between groups and individual samples are attributed to differences in n-alkanes and PAHs contents, which are influenced predominantly by sediment granulometry and sitespecific fluvial input. The predominant hydrocarbon source is biogenic, mainly terrigenous, with hardly any contribution from natural oil seeps, oil drill effluents and/or refined crude. The terrigenous source is corroborated by δ13C, δ15N, and OC/N of sediment organic matter. Time interval (1976–1977, 1984 and 1997) changes in hydrocarbon compositions and concentrations in CDPB are not significant.

Changes in coastline positions during the Holocene in the shelf of the Northwestern Black Sea

The first evidence for the reconnection of the Black Sea with the Mediterranean Sea are euryhaline mollusc species that appear in the bottom sediments. Lacustrine conditions existed over the larger part of study area at the beginning of the Holocene. Early Holocene beds are characterized by a wide distribution of continental facies (e.g. lacustrine-marshy and alluvial). The lacustrine phase was followed by a marine phase and the transition occurred around ca. 8.9–8.5 ka BP. The Holocene was marked by a gradual increase of Mytilus sp. shells in sediments. Reconstructions of coastline positions during the Holocene in the Northwestern Black Sea shelf are presented. Extensive sampling of the study area during several decades allowed the acquisition of a comprehensive data base for paleogeographic reconstructions. Positions of ancient coastlines are discussed. Analysis of relief features, lithological composition and bottom sediments distribution and faunal complexes allowed identification of paleofacies in the northwestern part of the Black Sea. Facial and paloegeographic maps of the Holocene discrete time intervals such as the Bugazian (from ca. 10.5–10 to 8.9–8.5 ka BP), the Vityazevian (from ca. 8.9–8.5 to 7.1–6.2 ka BP), the Kalamitian (from ca. 7.1–6.2 to 4.1–4.0 ka BP), and the Dzhemetinian (from ca. 4.1–4.0 to present) are presented. Dating of the sediments is based on uncalibrated radiocarbon determinations. Study of the granulometry of sediments provided evidence that supports the proposed ancient coastline positions. The samples from the cores recovered from different facial zones enabled the characterization of sedimentological environments for each time interval. The position of the early Holocene coastal sediments is marked out on the level of modern isobaths approximately from −25 to −35 m. In the range of time from ca. 8.9–8.5 to 7.1–6.2 ka BP, the coastline was located at depths from 20 to 25 m. The position of the coastline which existed from ca. 7.1–6.2 to 4.1–4 ka BP is allocated on the level of modern isobaths from −0 to −15 m. Comparison of the various positions of the coastline and their facies changes through time indicates that the Holocene transgression had a progressively and oscillatory course.

Classification of sediments by means of Self-Organizing Maps and sediment quality guidelines in sites of the southern Spanish coastline

This study was carried out to classify 112 marine and estuarine sites of the southern Spanish coastline (about 918 km long) according to similar sediment characteristics by means of artificial neural networks (ANNs) such as Self-Organizing Maps (SOM) and sediment quality guidelines from a dataset consisted of 16 physical and chemical parameters including sediment granulometry, trace and major elements, total N and P and organic carbon content. The use of ANNs such as SOM made possible the classification of the sampling sites according to their similar chemical characteristics. Visual correlations between geochemical parameters were extracted due to the powerful visual characteristics (component planes) of the SOM revealing that ANNs are an excellent tool to be incorporated in sediment quality assessments. Besides, almost 20% of the sites were classified as medium-high or high priority sites in order to take future remediation actions due to their high mean Effects Range-Median Quotient (m-ERMQ) value. Priority sites included the estuaries of the major rivers (Tinto, Odiel, Palmones, etc.) and several locations along the eastern coastline.

Limiting factors on the distribution of shell/tube-dwelling sipunculans

Many sipunculan species use empty gastropod shells or polychaete tubes as a resource to keep them safe from predation. Nonetheless, little is known about the extent to which the availability of this resource is involved in the distribution of these species.We examined shelter availability and sediment granulometry as factors to explain the distribution of shell-dwelling and/or tube-dwelling sipunculans. For this purpose, artificial sampling units with different sediment granulometry and different shelter availability were deployed at two localities. Four species have been reported, being three of them usually dwellers of vacant gastropod shells or polychaete tubes: Aspidosiphon (Aspidosiphon) muelleri, Phascolion (Phascolion) strombus strombus and Phascolion (Phascolion) caupo.Shelter availability was the main factor explaining the distribution and abundance of shell/tube-dwelling sipunculans. Samples in which shelter were added had an abundance of A. (A.) muelleri ten times higher than samples in which shelters were removed (p<0.01). Moreover, sipunculans selected preferably as shelter Ditrupa arietina tubes over gastropod shells. A strong linear correlation between body width and shelter internal diameter was found for A. (A.) muelleri (r=0.796, p<0.001).On the other hand, differences between localities were detected. However, these differences are not linked with the studied variables (shelter availability and granulometry), and have to be explained by other factors.

A baseline study of benthic community associated with Amphioxus Sand in subtropical Hong Kong

An annual investigation on the seasonal changes of benthic community structure associated with Amphioxus Sand was conducted at two sites in the eastern waters of subtropical Hong Kong, where three species of amphioxus, Branchiostoma belcheri, B. japonicum and B. malayanum coexist. A total of 84 species and 4169 individuals were recorded at Tai Long Wan, whereas a total of 87 species and 3915 individuals were recorded at Pak Lap Wan. Benthic polychaetes were dominant, including high abundance of Onuphis eremita and Prionospio malmgreni. Results of cluster analysis showed significant community structures between the two areas because of difference in sediment granulometry. However, temporal changes within these Amphioxus Sand communities were minimal. In general, the Amphioxus Sand communities in Hong Kong showed higher species richness of Polychaeta as compared with similar studies elsewhere, possibly implying an increased level of organic pollution in Hong Kong waters.

ReefBahia, an integrated GIS approach for coral reef conservation in Bahia, Brazil

Coral reefs around the world are facing serious threats. These fragile ecosystems are in need for conservation. The coastal state of Bahia hosts the most extensive and richest area of coral reefs in the South Atlantic Ocean. Assessment, planning and management of coral reef ecosystems are particularly challenging tasks. This work shows how the creation of a GIS improves the process of management, monitoring and conservation of the Bahian reef environments The initial data input started by the vectorization of 1) bathymetric data from the Bureau of Hydrography and Navigation (DHN), 2) shoreline and mangrove areas from Landsat 7 ETM + images, 3) near surface reefs from Quickbird images, and 4) coastal and marine protected areas of federal, state and local administrations. Geological, physical, biological and social information was then included in order to create a suitable marine GIS for conservation aims. The data includes information on sediment granulometry and transport patterns, rocky substrate outcrops, sea surface temperature, wave direction, rain precipitation, major contributing river discharge, artisanal fishery, benthic cover and bleaching data. ReefBahia GIS has provided essential information for a better understanding of coral reefs of the state of Bahia geological and ecological characteristics such as mapping, representation, connectivity and biodiversity of coral reefs, geological facies, Quaternary sedimentation, numeric modeling of wave refraction and monitoring of bleaching events.

Linkages between rocky reefs and soft-bottom habitats: Effects of predation and granulometry on sandy macrofaunal assemblages

The movement of animals and materials among habitats can have an important influence on the structure of assemblages. The nature of such linkages is, however, not always an obvious one. Here we examined the influence of rocky reefs on nearby sandy macrofaunal assemblages. A preliminary descriptive study confirmed the hypothesis that sediment granulometry differs in relation to distance to rocky reefs and so did the macrofaunal assemblage composition, and relative abundance of three of the most abundant taxa, and that this effect was generally consistent among locations. In addition, there was a significant effect of sediment structure on community structure of benthic assemblages. A subsequent manipulative experiment tested, in an interactive way, the effects of predation and sediment grain size in structuring macrofaunal assemblages adjacent to a rocky reef. At the scale of the assemblage (richness and composition), results showed that there was an effect of sand granulometry and distance to the reef, while predation had no effect. Predation affected the abundance of one of the most abundant taxa (un-identified amphipod sp.1) but this effect was consistent adjacent and away from the reef. Sand granulometry had no influence on the numbers of the most abundant taxa, while the abundance of two of these taxa (Catapaguroides timidus and Ervilia castanea) still varied according to distance to the reef. This study adds to the wider literature by suggesting that there can be important movements of materials and organisms from rocky reefs to adjacent soft-bottom habitats but that rock-associated predators and sand granulometry may have a limited influence in structuring the small-bodied sediment infauna close to reefs. This study also stresses the need for caution when ascribing the importance of ecological processes based on descriptive studies alone, even when results seem ecologically logical.

CHARACTERISTIC OF LITORAL SEDIMENT ON SINDULANG SATU COASTAL

Coastal area is defined as the interface point where sea and land meet. To the land the area is limited to the area influenced by the sea factors (wind, tide, and sea water infiltration), while to the sea is limited to the area influenced by the land factors. Special concern need to be addressed in regarding to the use of coastal area. As part of the coastal area, littoral zone is very dynamics due to factors of oceanography and human activities. The same fact is experienced by the littoral zone in Sindulang Satu. Physical change has been the fact in this littoral zone. In relation to the change, it is considered of importance to describe and analysis the characteristics of the sediment and related oceanography factors. Result of observation indicated that sediment in the littoral zone consist of fine sand, medium sand, very fine sand, coarse sand and pebbles. Silt and boulder were also found. Distribution of sediment granulometry showed that the littoral zone was dominated by fine sand material, bad sorted, asymetrical to small size and symmetrical granulometry, and mesokurtic. Tidal current is the type of current working in the littoral zone and it plays importance role in the sediment.

CHARACTERISTIC OF LITORAL SEDIMENT ON SINDULANG SATU COASTAL

Coastal area is defined as the interface point where sea and land meet. To the land the area is limited to the area influenced by the sea factors (wind, tide, and sea water infiltration), while to the sea is limited to the area influenced by the land factors. Special concern need to be addressed in regarding to the use of coastal area. As part of the coastal area, littoral zone is very dynamics due to factors of oceanography and human activities. The same fact is experienced by the littoral zone in Sindulang Satu. Physical change has been the fact in this littoral zone. In relation to the change, it is considered of importance to describe and analysis the characteristics of the sediment and related oceanography factors. Result of observation indicated that sediment in the littoral zone consist of fine sand, medium sand, very fine sand, coarse sand and pebbles. Silt and boulder were also found. Distribution of sediment granulometry showed that the littoral zone was dominated by fine sand material, bad sorted, asymetrical to small size and symmetrical granulometry, and mesokurtic. Tidal current is the type of current working in the littoral zone and it plays importance role in the sediment.

Application of non-linear quantile regression to macrozoobenthic species distribution modelling: comparing two contrasting basins

The occurrence and distribution of macrozoobenthos in estuaries are strongly related to sediment grain-size characteristics. However, statistical prediction of the distribution of benthic populations as a response to a single environmental gradient has proven to be difficult, because the focal variable may set upper limits to the abundance, but other (partly uncorrelated) variables may cause considerable deviation from the maximum. A multi-quantile regression approach is better suited to characterize biota–environment relationships than a single (average or boundary) estimation, because it shows the variation in responses and quantifies the relative importance of other unmeasured factors. Here, a univariate application of non-linear quantile regression is proposed to account for heteroskedasticity and non-linearity in the biological response to sediment grain size. The analysis was applied to a large macrozoobenthic dataset from the SW Delta area (The Netherlands) to compare the relationships between sediment granulometry and macrozoobenthos in 2 neighboring but differing temperate coastal ecosystems (Oosterschelde and Westerschelde). Preference of individual species for grain size was consistent between both systems, although in general, a slightly higher median grain size (ca. +60% in grain diameter) was preferred in the Oosterschelde than in the Westerschelde. The major difference in the community was, however, that mud-preferring species dominated the assemblage in the Westerschelde, and sand-preferring species dominated the Oosterschelde. Although the prevalence of muddy and sandy sediments in both systems is similar, in the Westerschelde, strong hydrodynamic stress is correlated with sandy habitats, causing impoverishment of assemblages at sandy sites. In the Oosterschelde, sandy sediments are usually associated with much more benign conditions and have the richest species assemblage.

Seabed habitat mapping employing single and multi-beam backscatter data: A case study from the western continental shelf of India

Acoustic backscatter from multi-beam echo-sounder (MBES) and dual-frequency single-beam echo-sounding systems (SBES) operable at 95kHz and 33/210kHz, respectively, were used to study the distribution of sediment texture and benthic macro-fauna along the central part of the western continental shelf of India (off Goa). To characterize the continental shelf seafloor, single-beam and multi-beam backscatter signals were acquired along with grab sediment samples. The relationships between processed acoustic backscatter strength, grain size, and benthic macro-fauna abundance were demonstrated employing clustering technique (PCA) and Geographic Information System (GIS) based mapping. The clustering analysis delineated that the backscatter values at three frequencies are strongly correlated with both substrate type and faunal functional groups. The preferences of deposit feeders (soft body benthic macro-fauna) for the fine-sediment regions and filter feeders (hard body benthic macro-fauna) for coarse sediment regions were linked to the variations in sediment granulometry as well as backscatter strengths in the study area. This study further demonstrates the utility of high frequency backscatter data employing echo-sounding systems towards the interpretation of seafloor sediments and benthic habitat characteristics across large areas of seafloor.

SUBDIVISION OF PANTANAL QUATERNARY WETLANDS: MODIS NDVI TIMESERIES IN THE INDIRECT DETECTION OF SEDIMENTS GRANULOMETRY

Abstract. The Pantanal is the world's largest wetland presenting a variety of ecological sub-regions. The region is characterized by seasonal floods followed by long droughts. At this period, some areas rapidly dry, while others remain soaked. The study hypothesis was based on the statement that this phenomenon cannot be totally explained by small relief variations but by the sediment granulometry: the pelitic sediments allow the soil to retain moisture longer, implying that the vegetation has greater possibilities of continuing photosynthetically active even during the drought. It was developed based on the spectral behaviour of MODIS products, validated by previous fieldwork. Using MODIS, we studied a large scale patterns in spatial and seasonal dynamics of the vegetation in different regions of Pantanal. So, two indirect parameters of the local physical environment – sediment granulometry and water availability – potentially can be estimated. We calculated the NDVI from MOD09GQ for rainy and dry seasons, generating triplets (NDVI/NIR and Red bands) that allowed to identify vegetation changes in those periods. The 16-days composites of NDVI (MOD13Q1) were used to generate a 5-year time-series for pixels associated with 161 locals sampled for granulometric analyses. The samples were taken in 10 different areas from the 20 geological and environmentally homologous areas delimited in this research. The clear tendency in the time-series confirms the working hypothesis, indicating that there is a high relationship between drought-related changes in vegetation extracted from NDVI and sediment texture, parameter that plays an important role in soil moisture, influencing the vegetation response to droughts.

Submerged macrophyte biomass distribution in the shallow saline lake Fuente de Piedra (Spain) as function of environmental variables

Aquatic macrophyte biomass, diaspore bank distribution and their relationship to spatial variability of depth, nutrients (nitrite, nitrate, ammonium and soluble reactive phosphorus) as well as sediment granulometry in an athalassohaline lake have been studied during one wet hydrological year. The results indicate that species growing in the lake show different spatial distribution patterns throughout the lake. Indirect gradient analysis (canonical analysis) results showed a first axis defined as a function of Ulva flexuosa Wulfen biomass which is, in turn, positively correlated with interstitial ammonium and Soluble Reactive Phosphorus (SRP). The second axis was mainly established due to Lamprothamnium papulosum (Wallr.) J. Groves biomass which correlated positively to depth and negatively to interstitial ammonium and SRP. These results revealed a NESW eutrophic gradient allowing the U. Flexuosa biomass proliferation. This phenomenon could increase the shadow effect over the rest of the macrophytes inhabiting this shallow lake. Moreover, the eutrophic harmful effect on the macrophyte physiology and over the diaspore bank could have important consequences in the survival of such important populations. The results reported in this study show the need for studies as the base to select sampling points for monitoring this wetland.