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Non-Linear Interactions Determine the Impact of Sea-Level Rise on Estuarine Benthic Biodiversity and Ecosystem Processes  [PDF]
Tsuyuko Yamanaka, David Raffaelli, Piran C. L. White
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068160
Abstract: Sea-level rise induced by climate change may have significant impacts on the ecosystem functions and ecosystem services provided by intertidal sediment ecosystems. Accelerated sea-level rise is expected to lead to steeper beach slopes, coarser particle sizes and increased wave exposure, with consequent impacts on intertidal ecosystems. We examined the relationships between abundance, biomass, and community metabolism of benthic fauna with beach slope, particle size and exposure, using samples across a range of conditions from three different locations in the UK, to determine the significance of sediment particle size beach slope and wave exposure in affecting benthic fauna and ecosystem function in different ecological contexts. Our results show that abundance, biomass and oxygen consumption of intertidal macrofauna and meiofauna are affected significantly by interactions among sediment particle size, beach slope and wave exposure. For macrofauna on less sloping beaches, the effect of these physical constraints is mediated by the local context, although for meiofauna and for macrofauna on intermediate and steeper beaches, the effects of physical constraints dominate. Steeper beach slopes, coarser particle sizes and increased wave exposure generally result in decreases in abundance, biomass and oxygen consumption, but these relationships are complex and non-linear. Sea-level rise is likely to lead to changes in ecosystem structure with generally negative impacts on ecosystem functions and ecosystem services. However, the impacts of sea-level rise will also be affected by local ecological context, especially for less sloping beaches.
Interpretation of benthic foraminiferal stable isotopes in subtidal estuarine environments
P. Diz, F. J. Jorissen, G. J. Reichart, C. Poulain, F. Dehairs, E. Leorri,Y.-M. Paulet
Biogeosciences (BG) & Discussions (BGD) , 2009,
Abstract: Here we present a novel approach for the interpretation of stable isotope signatures recorded in benthic foraminifera from subtidal estuarine environments. The stable isotopic composition (δ18O and δ13C) of living Ammonia tepida and Haynesina germanica is examined at four stations in the Auray River estuary (Gulf of Morbihan, France) sampled in two contrasting seasons, spring 2006 and winter 2007. Comparing benthic foraminiferal δ18O measurements with theoretical oxygen isotopic equilibrium values, calculated on the basis of water temperature and salinity measurements in the upper and lower estuary, i.e., T-S-δ18Oeq. diagrams, strongly suggests that foraminiferal faunas sampled at the four stations calcified during different periods of the year. This interpretation can be refined by using the benthic foraminiferal δ13C, which is mainly determined by the mixing of sea and river water. In the upper estuary foraminifera mainly calcified in early spring and winter, whereas in the lower estuary calcification mainly took place in spring, summer and autumn. This new method provides insight into the complexity of estuarine benthic foraminiferal stable isotope records. In addition, it can also be used to obtain new information on preferred calcification periods of benthic foraminiferal taxa in different parts of the estuary.
Interpretation of benthic foraminiferal stable isotopes in subtidal estuarine environments  [PDF]
P. Diz,F. J. Jorissen,G. J. Reichart,C. Poulain
Biogeosciences Discussions , 2009,
Abstract: Here we present a novel approach for the interpretation of stable isotope signatures recorded in benthic foraminifera from subtidal estuarine environments. The stable isotopic composition (δ18O and δ13C) of living Ammonia tepida and Haynesina germanica is examined in four stations in the Auray River estuary (Gulf of Morbihan, France) sampled in two contrasting seasons, spring 2006 and winter 2007. Comparing benthic foraminiferal δ18O measurements with theoretical oxygen isotopic equilibrium values, calculated on the basis of water temperature and salinity measurements in the upper and lower estuary, i.e., T S δ18Oeq. diagrams, strongly suggests that foraminiferal faunas sampled at the four stations calcified during different periods of the year. This interpretation can be refined by using the benthic foraminiferal δ13C which is mainly determined by the mixing of sea and river water. In the upper estuary foraminifera mainly calcified in early spring and winter, whereas in the lower estuary calcification took mainly place in spring, summer and autumn. This new method provides insight into the complexity of estuarine benthic foraminiferal stable isotope records. In addition, it can also be used to obtain new information on preferred calcification periods of benthic foraminiferal taxa in different parts of the estuary.
Bioactivity of Benthic and Picoplanktonic Estuarine Cyanobacteria on Growth of Photoautotrophs: Inhibition versus Stimulation  [PDF]
Viviana R. Lopes,Vitor M. Vasconcelos
Marine Drugs , 2011, DOI: 10.3390/md9050790
Abstract: Understanding potential biochemical interactions and effects among cyanobacteria and other organisms is one of the main keys to a better knowledge of microbial population structuring and dynamics. In this study, the effects of cyanobacteria from benthos and plankton of estuaries on other cyanobacteria and green algae growth were evaluated. To understand how the estuarine cyanobacteria might influence the dynamics of phytoplankton, experiments were carried out with the freshwater species Microcystis aeruginosa and Chlorella sp., and the marine Synechocystis salina and Nannochloropsis sp. exposed to aqueous and organic (70% methanol) crude extracts of cyanobacteria for 96 h. The most pronounced effect observed was the growth stimulation. Growth inhibition was also observed for S. salina and M. aeruginosa target-species at the highest and lowest concentrations of cyanobacterial extracts. The methanolic crude extract of Phormidium cf. chalybeum LEGE06078 was effective against S. salina growth in a concentration-dependent manner after 96 h-exposure. All of the cyanobacterial isolates showed some bioactivity on the target-species growth, i.e., inhibitory or stimulating effects. These results indicate that the analyzed cyanobacterial isolates can potentially contribute to blooms’ proliferation of other cyanobacteria and to the abnormal growth of green algae disturbing the dynamic of estuarine phytoplankton communities. Since estuaries are transitional ecosystems, the benthic and picoplanktonic estuarine cyanobacteria can change both freshwater and marine phytoplankton succession, competition and bloom formation. Furthermore, a potential biotechnological application of these isolates as a tool to control cyanobacteria and microalgae proliferation can be feasible. This work is the first on the subject of growth responses of photoautotrophs to cyanobacteria from Atlantic estuarine environments.
Shallow sublittoral benthic communities of the Laguna Estuarine System, South Brazil
Fonseca, Gustavo;Netto, Sérgio A.;
Brazilian Journal of Oceanography , 2006, DOI: 10.1590/S1679-87592006000100004
Abstract: sediment properties, microphytobenthos biomass (chlorophyll a and phaeopigments), and the structure of the benthic communities of the three main lagoons (mirim, imaruí and santo antonio) of the laguna estuarine system, south brazil, were analyzed during summer and winter. microphytobenthos biomass did not differ significantly among the lagoons, but showed higher values in the summer. the macrofauna was characterized by low species richness and the dominance of the gastropod heleobia australis, the tanaidean kalliapseudes schubartti and the bivalve erodona mactroides. the meiofauna was composed of 20 higher taxa and the nematodes dominated in all the lagoons and periods. desmodora (desmodora) sp.1, terschllingia sp. and microlaimus sp. were numerically the most important among the 74 nematode species registered. this study showed that, in the laguna estuarine system, differences in the benthos among lagoons and periods were dependent on the fauna component analyzed. whilst macrofauna and nematodes were significantly more diverse in the inner stations, in the mirim lagoon, the number of meiofauna taxa did not differ significantly among the lagoons and the diversity and evenness were highest in santo antonio. these results were a response of the fauna to the salinity oscillations coupled with the heterogeneity of the sediment in the lagoons. the temporal variability of the fauna, macrofauna being more abundant in the summer and meiofauna in the winter, could be related to the different life strategies of these groups.
Exploring Benthic Biodiversity Patterns and Hotspots on European Margin Slopes  [PDF]
Roberto Danovaro,Miquel Canals,Serge Heussner,Nikolaos Lampadariou
Oceanography , 2009,
Abstract: There is increasing evidence that continental slope ecosystems represent one of the major repositories of benthic marine biodiversity. The enhanced levels of biodiversity along slopes are hypothesized to be a source of biodiversity for continental shelves and deeper basins. Continental margins are increasingly altered by human activities, but the consequences of these anthropogenic impacts on benthic biodiversity and ecosystem functioning are almost completely unknown. Thus, there is an urgent need to gather sufficient information to enable us to understand patterns and drivers of deep-sea biodiversity along continental margins. Although the local diversity of some deep open slope ecosystems is moderately well documented, very little is known about the biodiversity of these systems at greater spatial scales. Topographic setting, hydrodynamic forcing, and the biogeochemical characteristics of the deep-sea floor may play key roles in promoting and sustaining high biodiversity along the open slopes of continental margins. HERMES provided the opportunity to acquire a significant volume of information on the biodiversity, trophic conditions, and topographic characteristics of open slopes across European margins, increasing our knowledge of the latitudinal, longitudinal, and bathymetric patterns of benthic biodiversity, and extending our comprehension of the mechanisms driving deep-sea biodiversity and its potential loss. Improved knowledge of these processes is needed to inform policy decisions for promoting sustainable management of open slopes and deep-sea ecosystems along continental margins.
Culture of estuarine benthic and nectonic first trophic level feeders
K.V Singarajah
Brazilian Journal of Oceanography , 1980, DOI: 10.1590/s1679-87591980000200072
Abstract: The paper deals with some base trophic factors in relation to two herbivores, namely oysters and mullets, which derive their energy directly from the first trophic level of an estuarine ecosystem. The analysis of the gut contents of both organisms has shown that they feed mostly on micro-organisms, especially planktonic and benthic diatoms, and a significant percentage of detritus materials, including inorganic particles, is always present. Their dietary components are very much related to seasonal abundance of food production of the estuary. Current yields of oysters and mullets are far too low and food source is not a limiting factor for their production on large scale. Tidal flows, particularly in relation to salinity, have profound effect on culture grounds. Mortality is largely due to predation.
Relating Remotely Sensed Optical Variability to Marine Benthic Biodiversity  [PDF]
Kristjan Herkül, Jonne Kotta, Tiit Kutser, Ele Vahtm?e
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0055624
Abstract: Biodiversity is important in maintaining ecosystem viability, and the availability of adequate biodiversity data is a prerequisite for the sustainable management of natural resources. As such, there is a clear need to map biodiversity at high spatial resolutions across large areas. Airborne and spaceborne optical remote sensing is a potential tool to provide such biodiversity data. The spectral variation hypothesis (SVH) predicts a positive correlation between spectral variability (SV) of a remotely sensed image and biodiversity. The SVH has only been tested on a few terrestrial plant communities. Our study is the first attempt to apply the SVH in the marine environment using hyperspectral imagery recorded by Compact Airborne Spectrographic Imager (CASI). All coverage-based diversity measures of benthic macrophytes and invertebrates showed low but statistically significant positive correlations with SV whereas the relationship between biomass-based diversity measures and SV were weak or lacking. The observed relationships did not vary with spatial scale. SV had the highest independent effect among predictor variables in the statistical models of coverage-derived total benthic species richness and Shannon index. Thus, the relevance of SVH in marine benthic habitats was proved and this forms a prerequisite for the future use of SV in benthic biodiversity assessments.
BIODIVERSITY OF BENTHIC DIATOM AND PRIMARY PRODUCTIVITY OF BENTHIC MICRO-FLORA IN MANGROVE FORESTS ON CENTRAL JAVA  [cached]
Ign. Boedi Hendrarto and Mustofa Nitisuparjo
Journal of Coastal Development , 2011,
Abstract: A study to determine biodiversity related to ecological function of secondary mangrove forests at central Java had been carried out in three different locations viz. Rembang, Demak and Pemalang coasts. Location of sampling was selected systematically in three levels of inundation within both lower and higher densities of mangrove. Sediment samples were collected randomly with four replications. A lens tissue trapping method was applied to collect living benthic diatoms. Primary productivity was measured in-situ in the locations as production of carbon per unit area per unit time. It was determined by dissolved oxygen content measured by the bell jar method. Data were then analyzed using biodiversity index (Shannon-Wiener index), ANOVA, regression and cluster multivariate analysis for biodiversity. Totally, 86 benthic diatom species had been found and the benthic diatom community assemblage was dominated by Amphora coffeaeformis, Diploneis crabro, Diploneis smithi, Navicula elliptica, Pleurosigma sp., Stauropsis majuscula and Surirella gemma. Benthic diatom abundance was 8.6750 x 104 to 18.9626 x 104 cell/m2, where the highest was found in Demak and the lowest was in Pemalang. Abundance of the diatom does not always have significant relation (P > 0.05) to both inundation levels and mangrove density; however, this was more depended on location. The assemblage of benthic diatom community was more similar in Rembang and Pemalang compared to that in Demak, however the biodiversity index tended to be higher in the lower mangrove density. The benthic micro-flora primary productivity was 120 to 342 mg C/m2/hour and had no significant relation (P > 0.05) to abundance of benthic diatom. It was revealed that the optimum density of mangrove to have the highest benthic micro-flora primary productivity was between 8000 to 10000 trees/ha.
Seasonal dynamics of benthic communities in a shallow sublitoral site of Laguna estuarine system (South, Brazil) Seasonal dynamics of benthic communities in a shallow sublitoral site of Laguna estuarine system (South, Brazil)
A. Z. Meurer,S. A. Netto
Brazilian Journal of Aquatic Science and Technology , 2007,
Abstract: The seasonal variability of the benthic community in a shallow sublittoral site was analyzed at the Laguna Estuarine System, a chocked lagoon in South Brazil. Seasonal replicate samples for the microphytobenthos, meiofauna and macrofauna were undertaken from October 2003 to October 2004. The analysis of the different component of the benthos permitted to show a clear temporal asynchrony in the microphytobenthos biomass, meiofauna and macrofauna univariate measures increase and decline. Sediment chlorophyll a and phaeopigments followed a similar seasonal trend, with low biomass in the winter, higher in the summer and intermediate values in spring and autumn. The benthic fauna components of the Laguna Estuarine System also showed a clear seasonal oscillation, but with an opposite pattern of variation. Whilst the number of species and abundance of the macrofauna were significantly higher in the spring and summer, for the meiofauna, both the number of taxa and abundances were significantly higher during the winter and autumn. The results of this study suggested that the divergent seasonal variations of the meiofauna and macrofauna may be linked to their different life strategies, and that biological interactions between meiofauna and macrofauna may also play a significant role in structuring these communites. The seasonal variability of the benthic community in a shallow sublittoral site was analyzed at the Laguna Estuarine System, a chocked lagoon in South Brazil. Seasonal replicate samples for the microphytobenthos, meiofauna and macrofauna were undertaken from October 2003 to October 2004. The analysis of the different component of the benthos permitted to show a clear temporal asynchrony in the microphytobenthos biomass, meiofauna and macrofauna univariate measures increase and decline. Sediment chlorophyll a and phaeopigments followed a similar seasonal trend, with low biomass in the winter, higher in the summer and intermediate values in spring and autumn. The benthic fauna components of the Laguna Estuarine System also showed a clear seasonal oscillation, but with an opposite pattern of variation. Whilst the number of species and abundance of the macrofauna were significantly higher in the spring and summer, for the meiofauna, both the number of taxa and abundances were significantly higher during the winter and autumn. The results of this study suggested that the divergent seasonal variations of the meiofauna and macrofauna may be linked to their different life strategies, and that biological interactions between meiofauna and macrofauna may also pl
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