scholarly journals Responses of phytoplankton benthic propagules to macronutrient enrichment and varying light intensities: elucidation from monsoonal estuaries

2021 ◽  
Author(s):  
Jagadish S Patil ◽  
K Sathish
Keyword(s):  
River Discharge ◽  
Photosynthetic Activity ◽  
Maximum Growth ◽  
Single Species ◽  
Coastal Sediments ◽  
Light Intensities ◽  
Phosphate Silicate ◽  
Total Community ◽  
Ecological Importance ◽  
Riverine Systems

Abstract The ecological importance of phytoplankton-benthic-propagules (PBP) from coastal sediments, except tropical-monsoonal-estuaries/coast, is well documented. Monsoonal estuaries recieves a high amount of benthic suspension (sediments, other detritus, PBP, and nutrients) due to high river-discharge during monsoon, bringing drastic changes in the environment (affecting water transparency, macronutrients concentration, and salinity), which in turn influence the plankton and phytoplankton per se. This study elucidates PBP germination and subsequent growth representing downstream, midstream, and upstream locations of monsoon-influenced Mandovi-Zuari riverine systems (Goa, India), to macronutrients (nitrate, phosphate, silicate, and in-combination) and light-intensities at higher salinity. Since, PBP, after introduction to estuary, experience higher salinity conditions with reduced river-discharge salinity of ~35 PSU was selected. Diatoms dominated the viable PBP community, but the maximum growth and sustained photosynthetic activity were observed when macronutrients were supplied in combination then individual supply. Here, the utility of the variable fluorescence technique in PBP resurrection (detection of viability and responses) was also explored. The PBP lag-period was similar for macronutrients but decreased with an increase in light-intensity. For PBP (germination and photosynthetic activity), light-intensities drive the rate of improvement/development, whereas the nutrients are essential for maintaining vegetative population upon germination. The PBP dominance of common planktonic species (Skeletonema and Thalassiosira) along the river also signifies the role of seawater intrusion in distribution. Both species are light-sensitive, responded similarly, and known to cause single species blooms and contributed significantly to the total community in the region, but on different occasions depending on the species tolerance to salinity.

scholarly journals Combined Effect of Light and Temperature on the Production of Saxitoxins in Cylindrospermopsis raciborskii Strains

Toxins ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 38 ◽  
Author(s):  
Marcella Mesquita ◽  
Miquel Lürling ◽  
Fabiane Dorr ◽  
Ernani Pinto ◽  
Marcelo Marinho
Keyword(s):  
Maximum Growth ◽  
Combined Effect ◽  
Cylindrospermopsis Raciborskii ◽  
Tropical Regions ◽  
Batch Cultures ◽  
Light Intensities ◽  
Cell Quota ◽  
Wide Range ◽  
Lower Light ◽  
Effect Of Light

Cylindrospermopsis raciborskii is a potentially toxic freshwater cyanobacterium that can tolerate a wide range of light and temperature. Due to climatic changes, the interaction between light and temperature is studied in aquatic systems, but no study has addressed the effect of both variables on the saxitoxins production. This study evaluated the combined effect of light and temperature on saxitoxins production and cellular quota in C. raciborskii. Experiments were performed with three C. raciborskii strains in batch cultures under six light intensities (10, 40, 60, 100, 150, and 500 μmol of photons m−2 s−1) and four temperatures (15, 20, 25, and 30 °C). The growth of C. raciborskii strains was limited at lower temperatures and the maximum growth rates were obtained under higher light combined with temperatures equal or above 20 °C, depending on the strain. In general, growth was highest at 30 °C at the lower light intensities and equally high at 25 °C and 30 °C under higher light. Highest saxitoxins concentration and cell-quota occurred at 25 °C under high light intensities, but were much lower at 30 °C. Hence, increased temperatures combined with sufficient light will lead to higher C. raciborskii biomass, but blooms could become less toxic in tropical regions.

scholarly journals Depth alone is an inappropriate proxy for physiological change in the mesophotic coralAgaricia lamarcki

2019 ◽  
Vol 99 (7) ◽  
pp. 1535-1546 ◽  
Author(s):  
Jack H. Laverick ◽  
Tamara K. Green ◽  
Heidi L. Burdett ◽  
Jason Newton ◽  
Alex D. Rogers
Keyword(s):  
Photosynthetic Activity ◽  
Single Species ◽  
Pulse Amplitude ◽  
Pulse Amplitude Modulation ◽  
Depth Range ◽  
Site Variation ◽  
Depth Ranges ◽  
Response To Environmental Change ◽  
Pulse Amplitude Modulation Fluorometry ◽  
Isotope Analyses

AbstractThe physiology of mesophotic Scleractinia varies with depth in response to environmental change. Previous research has documented trends in heterotrophy and photosynthesis with depth, but has not addressed between-site variation for a single species. Environmental differences between sites at a local scale and heterogeneous microhabitats, because of irradiance and food availability, are likely important factors when explaining the occurrence and physiology of Scleractinia. Here, 108 colonies ofAgaricia lamarckiwere sampled from two locations off the coast of Utila, Honduras, distributed evenly down the observed 50 m depth range of the species. We found that depth alone was not sufficient to fully explain physiological variation. Pulse Amplitude-Modulation fluorometry and stable isotope analyses revealed that trends in photochemical and heterotrophic activity with depth varied markedly between sites. Our isotope analyses do not support an obligate link between photosynthetic activity and heterotrophic subsidy with increasing depth. We found thatA. lamarckicolonies at the bottom of the species depth range can be physiologically similar to those nearer the surface. As a potential explanation, we hypothesize sites with high topographical complexity, and therefore varied microhabitats, may provide more physiological niches distributed across a larger depth range. Varied microhabitats with depth may reduce the dominance of depth as a physiological determinant. Thus,A. lamarckimay ‘avoid’ changes in environment with depth, by instead existing in a subset of favourable niches. Our observations correlate with site-specific depth ranges, advocating for linking physiology and abiotic profiles when defining the distribution of mesophotic taxa.

scholarly journals The order Tethyida (Porifera) in California: taxonomy, systematics, and the first member of the family Hemiasterellidae in the Eastern Pacific

2020 ◽  
Author(s):  
Thomas L. Turner
Keyword(s):  
Kelp Forest ◽  
Single Species ◽  
Ecological Monitoring ◽  
Eastern Pacific ◽  
The Third ◽  
Morphological Taxonomy ◽  
The Family ◽  
Ecological Importance

AbstractSponges (phylum Porifera) are ubiquitous inhabitants of marine ecosystems and have been shown to provide substantial ecosystem services. Despite this ecological importance, the sponge fauna in California has received little study. Here I use a collection of kelp forest sponges to describe the diversity of the order Tethyida in California. This order contains the genus Tethya, which has been included in long-term ecological monitoring projects. I show that Tethya vacua is a junior synonym of Tethya californiana, and thus all Tethya populations known in California belong to a single species. Genetic data from California’s only Timeidae, Timea authia, indicate that this species is in fact in the Tethyidae and is the third known member of the genus Tethytimea. I also describe the first member of the family Hemiasterellidae from the Eastern Pacific, Galaxia gaviotensis gen. nov. sp. nov. By combining field photographs, morphological taxonomy, and phylogenetic analysis of these samples, this work will facilitate future efforts to understand the evolution of this order and the ecological role of sponges in the California kelp forest.

scholarly journals The Interplay of Phototrophic and Heterotrophic Microbes Under Oil Exposure: A Microcosm Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Manoj Kamalanathan ◽  
Kathleen A. Schwehr ◽  
Jessica M. Labonté ◽  
Christian Taylor ◽  
Charles Bergen ◽  
...  
Keyword(s):  
Photosynthetic Activity ◽  
Direct Reduction ◽  
Marine Ecosystem ◽  
Major Elements ◽  
Microbial Interactions ◽  
Substrate Uptake ◽  
Heterotrophic Metabolism ◽  
Ecological Importance ◽  
Oil Exposure

Microbial interactions influence nearly one-half of the global biogeochemical flux of major elements of the marine ecosystem. Despite their ecological importance, microbial interactions remain poorly understood and even less is known regarding the effects of anthropogenic perturbations on these microbial interactions. The Deepwater Horizon oil spill exposed the Gulf of Mexico to ∼4.9 million barrels of crude oil over 87 days. We determined the effects of oil exposure on microbial interactions using short- and long-term microcosm experiments with and without Macondo surrogate oil. Microbial activity determined using radiotracers revealed that oil exposure negatively affected substrate uptake by prokaryotes within 8 h and by eukaryotes over 72 h. Eukaryotic uptake of heterotrophic exopolymeric substances (EPS) was more severely affected than prokaryotic uptake of phototrophic EPS. In addition, our long-term exposure study showed severe effects on photosynthetic activity. Lastly, changes in microbial relative abundances and fewer co-occurrences among microbial species were mostly driven by photosynthetic activity, treatment (control vs. oil), and prokaryotic heterotrophic metabolism. Overall, oil exposure affected microbial co-occurrence and/or interactions possibly by direct reduction in abundance of one of the interacting community members and/or indirect by reduction in metabolism (substrate uptake or photosynthesis) of interacting members.

scholarly journals Larval growth and survival in Indian Butter Catfish, Ompok bimaculatus (Bloch): effect of light intensity and photoperiod

2019 ◽  
Author(s):  
Kalpana Arambam ◽  
Pradyut Biswas ◽  
Soibam Khogen Singh ◽  
A. B. Patel ◽  
Alok Kumar Jena ◽  
...  
Keyword(s):  
Light Intensity ◽  
Larval Growth ◽  
Maximum Growth ◽  
Continuous Darkness ◽  
Growth And Survival ◽  
Light Intensities ◽  
Randomized Design ◽  
Significant Difference ◽  
Ompok Bimaculatus ◽  
Effect Of Light

AbstractTwo sequential indoor rearing trials each of 21 days duration were conducted to investigate the effect of light intensity and photoperiod respectively on the growth and survival of Ompok bimaculatus larvae. In first trial, five different light intensities viz. 0, 300, 500, 900, 1200 lx were applied randomly to 800 larvae (0.003 g; 0.51 cm) stocked in triplicate following a completely randomized design into aquarium (30.0 x 15.0 x 15.0 cm) tanks. Sequentially, in second trial, five photoperiod cycles (light: dark, L: D) namely, 24L: 0D, 16L: 8D, 12L: 12D, 8L: 16D and 0L: 24D in combination with the best performing light intensity (300 lx) as observed from the first trial were employed in triplicates in similar set up. From the first trial, significantly higher survival was observed in 0 and 300 lx, whereas growth was highest in 900 lx (P < 0.05). In the second trial, survival was higher in continuous darkness (0L: 24D), whereas, maximum growth was recorded in 24L: 0D and 16L: 8D groups (P < 0.05). Performance index (PI) showed no significant difference (P > 0.05) among 0 and 300 lx light intensities, but were reduced at higher light intensities. The lowest PI was found in 12L: 12D and 8L: 16D condition but did not have any effect in other photoperiod cycles. Overall, from the present study it can be concluded that growth of the larvae is found to be higher in higher light intensity (900lx) and longer photoperiodic cycles (24L: 0D and 16L: 8D), however, better survival was recorded in total dark conditions suggesting that continuous dark condition is recommended for better hatchery performance of the larvae.

Growth kinetics of Marquis wheat. II. Carbon dioxide dependence

1972 ◽  
Vol 50 (4) ◽  
pp. 883-889 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Carbon Dioxide ◽  
Light Intensity ◽  
Carbon Dioxide Concentration ◽  
Dry Weight ◽  
Maximum Growth ◽  
Carbon Dioxide Enrichment ◽  
Low Light ◽  
Growth Coefficient ◽  
Light Intensities ◽  
Wide Range

Marquis wheat was grown in growth rooms with four different concentrations of carbon dioxide and four to seven different intensities of light in a 16-h photoperiod at 25 °C. Growth was expressed quantitatively as the pseudo-first-order rate coefficient. Carbon dioxide stimulated growth, but the effect was greater the lower the light intensity in opposition to the known effect on photosynthesis. Carbon dioxide and light, in effect, did not influence the "rate" of growth of wheat additively but, rather, mutually compensated over a wide range. The growth coefficient of the roots was a little less than that of the shoots at all carbon dioxide concentrations and light intensities, probably owing to the cost of translocation. However, root growth benefited most from carbon dioxide enrichment at low light intensities. At intermediate light intensity there appeared to be a carbon dioxide concentration optimal for shoot growth. Carbon dioxide enrichment did not influence the maximum growth coefficient of Marquis wheat with respect to light intensity. The light-using efficiency of growth, calculated for vanishingly low light intensity at which it is maximal, was maximal for shoots at 1300 ppm CO2 but that for laminal area and root dry weight increased with CO2 to 2200 ppm at which the value for "leaves" was nearly fourfold that for roots. Unlike photosynthesis, the stimulation of growth by raised CO2 concentration was accomplished by increased efficiency of, and not capacity for, the net photosynthetic use of light.

Energy and nutrient fluxes from rivers and streams into terrestrial food webs

2006 ◽  
Vol 57 (1) ◽  
pp. 15 ◽  
Author(s):  
Andrea Ballinger ◽  
P. S. Lake
Keyword(s):  
Food Webs ◽  
River Regulation ◽  
Ecological Impacts ◽  
Allochthonous Inputs ◽  
Productivity Gradients ◽  
Research Questions ◽  
Ecological Importance ◽  
Landscape Scales ◽  
Riverine Systems ◽  
Exchange Surface

Ecologists long have been aware that there is flux of energy and nutrients from riverine systems to the surrounding terrestrial landscape and vice versa. Riparian ecotones are diverse and ecologically important. Consequently, there is substantial literature examining faunal-mediated transfers of energy and nutrients from rivers into terrestrial food webs. A wide variety of taxa has been shown to utilise riparian resources, from species specialised for existence at the aquatic–terrestrial interface to opportunistic predators and scavengers. Outputs from rivers may be influenced by productivity gradients, channel geometry and the condition of the exchange surface. Until recently, consideration of faunal-transferred, allochthonous inputs has been peripheral to other research questions. The development of general models of inter-habitat transfers, together with advances in technology, has placed questions about the ecological importance of riverine outputs squarely on the research agenda. Researchers now are investigating how aquatic subsidies influence food-web dynamics at landscape scales. However, ecologists continue to largely ignore subsidisation of terrestrial food webs by energy and nutrients from floodwaters in lowland river–floodplain systems. The dearth of information about the benefits of flooding to terrestrial consumers appears to have resulted in underestimation of the gross ecological impacts of river regulation.

scholarly journals Assessing the sustainability of harvest of the European Turtle-dove along the European western flyway

2019 ◽  
Vol 30 (4) ◽  
pp. 506-521 ◽  
Author(s):  
HERVÉ LORMÉE ◽  
CHRISTOPHE BARBRAUD ◽  
WILL PEACH ◽  
CARLES CARBONERAS ◽  
JEAN DOMINIQUE LEBRETON ◽  
...  
Keyword(s):  
Action Plan ◽  
Maximum Growth ◽  
Single Species ◽  
European Population ◽  
Maximum Growth Rate ◽  
Adult Survival ◽  
Hunting Bag ◽  
Management Objectives ◽  
Wide Range ◽  
Turtle Dove

SummaryWith a decline exceeding 30% over three generations, the once-common European Turtle-dove is now considered globally threatened by IUCN. As a legal game species in 10 European countries, the recent International Single Species Action Plan for this species highlighted the need to carry out an assessment of the sustainability of current levels of hunting. In 2013–2014, the Western European population was estimated at 1.3–2.1 million pairs, and the hunting bag in the same region to be 1.1 million birds. Using the Demographic Invariant Method, we assessed whether current levels of hunting harvest within Europe constitute overexploitation of the western flyway European Turtle-dove population. We calculated the maximum growth rate λmax that a population might achieve in the absence of any additive mortality. Then we estimated the potential maximum harvestable population fraction (P) allowed by excess population growth. We explored a wide range of plausible scenarios relating to assumed demographic rates, geographic scope of the flyway and management objectives. λmax was estimated to lie between 1.551 and 1.869. Current levels of hunting along the western flyway are more than double the sustainable fraction (P) under all suitably conservative scenarios, and only fall below this threshold under the most restrictive assumptions. We conclude that current levels of legal hunting along the western flyway are unlikely to be sustainable. Reducing uncertainty associated with assessments of the sustainability of turtle dove hunting will require improved information on (in order of decreasing importance) current levels of hunting, adult survival, age structure and population size.

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