scholarly journals Settlement of larvae from four families of corals in response to a crustose coralline alga and its biochemical morphogens

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Taylor N. Whitman ◽  
Andrew P. Negri ◽  
David G. Bourne ◽  
Carly J. Randall

Abstract Healthy benthic substrates that induce coral larvae to settle are necessary for coral recovery. Yet, the biochemical cues required to induce coral settlement have not been identified for many taxa. Here we tested the ability of the crustose coralline alga (CCA) Porolithon onkodes to induce attachment and metamorphosis, collectively termed settlement, of larvae from 15 ecologically important coral species from the families Acroporidae, Merulinidae, Poritidae, and Diploastreidae. Live CCA fragments, ethanol extracts, and hot aqueous extracts of P. onkodes induced settlement (> 10%) for 11, 7, and 6 coral species, respectively. Live CCA fragments were the most effective inducer, achieving over 50% settlement for nine species. The strongest settlement responses were observed in Acropora spp.; the only non-acroporid species that settled over 50% were Diploastrea heliopora, Goniastrea retiformis, and Dipsastraea pallida. Larval settlement was reduced in treatments with chemical extracts compared with live CCA, although high settlement (> 50%) was reported for six acroporid species in response to ethanol extracts of CCA. All experimental treatments failed (< 10%) to induce settlement in Montipora aequituberculata, Mycedium elephantotus, and Porites cylindrica. Individual species responded heterogeneously to all treatments, suggesting that none of the cues represent a universal settlement inducer. These results challenge the commonly-held notion that CCA ubiquitously induces coral settlement, and emphasize the critical need to assess additional cues to identify natural settlement inducers for a broad range of coral taxa.

2021 ◽  
Vol 82 (1) ◽  
Author(s):  
Juliana Amaka Ugwu

Abstract Background Iroko gall bug, Phytolyma fusca Walker, is a major insect pest of Milicia excelsa (Iroko) seedling hampering its propagation in West Africa. Milicia excelsa is an indigenous forest timber tree in the tropical rain forest of West Africa with a very high value in international trade due to its wood quality. Sustainable management of P. fusca infestations on Iroko seedlings have not been achieved due to their cryptic nature and multivoltine generations. This study evaluated the residual and contact effects of crude ethanol and aqueous extracts of four plants (Azadirachta indica, Jatropha curcas, Piper guineense, and Aframomum melegueta) on adult P. fusca in the laboratory and field. Results All the extracts had residual effects and contact effects on adult insects in the laboratory at 75% and 100% concentrations of applications. Azadirachta indica, P. guineense, and A. melegueta gave 80–100% adult mortality at both concentrations in the laboratory; their efficacies were comparable to cypermethrin. The ethanol extracts of P. guineense and A. indica were more effective than other extracts in protecting the seedlings against Phytolyma infestations in the field. They significantly (p < 0.01) reduced infestation compared to other extracts and control. Ethanol extracts of the tested plant materials were more effective than their aqueous extracts both in the laboratory and field. Conclusion The results proved that P. guineense and A. indica extracts were very potent and promising in protecting Milicia excelsa seedlings against Phytolyma fusca infestations and they can be used in the early management of Phytolyma infestations in the field.


2016 ◽  
Author(s):  
Merinda C. Nash ◽  
Sophie Martin ◽  
Jean-Pierre Gattuso

Abstract. Red calcareous coralline algae are thought to be among organisms the most vulnerable to ocean acidification due to the high solubility of their magnesium calcite skeleton. Although, skeletal mineralogy is proposed to change as CO2 and temperature continues rising, there is currently very little information available on the response of coralline algal carbonate mineralogy to near-future changes in pCO2 and temperature. Here we present results from a one-year controlled laboratory experiment to test mineralogical responses to pCO2 and temperature in the Mediterranean crustose coralline alga (CCA) Lithophyllum cabiochae. Our results show that Mg incorporation is mainly constrained by temperature (+1 mol% MgCO3 for an increase of 3 °C) and there was no response to pCO2. This suggests that L. cabiochae thalli have the ability to buffer calcifying medium against ocean acidification, enabling them to continue to deposit Mg-calcite with a significant mol% MgCO3 under elevated pCO2. Analyses of CCA dissolution chips showed a decrease in Mg content after 1 year for all treatments but this was not affected by pCO2 nor by temperature. Our findings suggest that biological processes exert a strong control on calcification on Mg-calcite and that CCA may be more resilient under rising CO2 than previously thought. However, previously demonstrated increased skeletal dissolution with ocean acidification will still have major consequences for the stability and maintenance of Mediterranean coralligenous habitats.


2016 ◽  
Vol 8 (3) ◽  
pp. 333 ◽  
Author(s):  
Abdullahi Aliyu ◽  
Alkali BR ◽  
Yahaya MS ◽  
Garba A ◽  
Adeleye SA ◽  
...  

<p>The aqueous and ethanol extracts of the bark of<em> Khaya senegalensis</em> were screened for their phytochemical constituents and preliminary antibacterial activity against <em>Bacillus subtilis, Escherichia coli</em> and<em> Proteus mirabilis. </em>The minimum inhibitory concentration (MIC) of the plant on the tested organisms was determined using multiple tubes method.</p><p>Alkaloids, anthraquinones, glycosides, tannins and steroids were detected in both extracts.</p><p>The ethanol and aqueous extracts of the plant showed antibacterial activity against <em>B. subtilis and E. coli,</em> with the aqueous extracts having more activity than those of ethanol. However the growth of<em> P. mirabilis</em> was not inhibited by either of the extracts. The MIC value was determined to be 50 mg/ml for<em> B. subtilis </em>and<em> E. coli. </em>The results are suggestive of considerable antibacterial activity of<em> K. senegalensis </em>and may justify its use in the treatment of bacterial diseases by herbalists or traditional healers.</p>


2018 ◽  
Vol 14 (7) ◽  
pp. 20180371 ◽  
Author(s):  
Maggie D. Johnson ◽  
Robert C. Carpenter

Ocean acidification (OA) and nutrient enrichment threaten the persistence of near shore ecosystems, yet little is known about their combined effects on marine organisms. Here, we show that a threefold increase in nitrogen concentrations, simulating enrichment due to coastal eutrophication or consumer excretions, offset the direct negative effects of near-future OA on calcification and photophysiology of the reef-building crustose coralline alga, Porolithon onkodes . Projected near-future pCO 2 levels (approx. 850 µatm) decreased calcification by 30% relative to ambient conditions. Conversely, nitrogen enrichment (nitrate + nitrite and ammonium) increased calcification by 90–130% in ambient and high pCO 2 treatments, respectively. pCO 2 and nitrogen enrichment interactively affected instantaneous photophysiology, with highest relative electron transport rates under high pCO 2 and high nitrogen. Nitrogen enrichment alone increased concentrations of the photosynthetic pigments chlorophyll a , phycocyanin and phycoerythrin by approximately 80–450%, regardless of pCO 2 . These results demonstrate that nutrient enrichment can mediate direct organismal responses to OA. In natural systems, however, such direct benefits may be counteracted by simultaneous increases in negative indirect effects, such as heightened competition. Experiments exploring the effects of multiple stressors are increasingly becoming important for improving our ability to understand the ramifications of local and global change stressors in near shore ecosystems.


2019 ◽  
Vol 49 (6) ◽  
pp. 1014-1028 ◽  
Author(s):  
Chaimae Rais ◽  
Asmae Driouch ◽  
Chaimae Slimani ◽  
Aymane Bessi ◽  
Mounyr Balouiri ◽  
...  

Purpose This paper aims to evaluate the antimicrobial and antioxidant activity of ethanol, methanol and aqueous extracts of the jujube fruit. Design/methodology/approach The fruit samples were harvested from Ziziphus lotus L. in three regions of Morocco: Aïn Chifae (Immouzer), Saiss (Fez) and Guercif. The fruit extracts were obtained by Soxhlet method using ethanol, methanol and water, and then a phytochemical screening was done for each extract. Total phenolic and total flavonoids contents were also determined. Afterward, the antimicrobial activity of the studied extracts was evaluated using the broth microdilution method. To estimate the total antioxidant effect of these extracts, the DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging and phosphomolybdate tests were performed. Findings Results showed that the highest content of polyphenols and flavonoids was found for ethanol and methanol extracts, while the lowest content was found in the aqueous extracts for all populations studied. Thus, results showed that the highest content of phenolic compounds was recorded in the population of Fez. Methanol extract of this population was the richest in polyphenols (30.36 mg/g) and in flavonoids (13.03 mg/g). The antimicrobial tests showed that Enterococcus faecalis and Pseudomonas aeruginosa were the most sensitive (6.25 mg/ml), compared to the other tested strains. Based on the minimal bactericidal concentrations/minimal fungicidal concentration or MFC/MIC ratio, it seems that ethanol extracts showed a bactericidal effect against Escherichia coli, Staphylococcus aureus and Bacillus subtillis, and a bacteriostatic effect against Enterococcus faecalis. On the other hand, the methanol extract showed bacteriostatic effect against Enterococcus faecalis and Pseudomonas aeruginosa. In addition, methanol extracts of Ziziphus lotus have significant antioxidant potent. Originality/value Methanol and ethanol extracts of Ziziphus lotus fruit have demonstrated strong antimicrobial effect. Moreover, the authors were able to show that the extract of Ziziphus lotus fruit has a very important antioxidant power.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
M. Azizur Rahman ◽  
Jochen Halfar ◽  
Walter H. Adey ◽  
Merinda Nash ◽  
Carlos Paulo ◽  
...  

2017 ◽  
Vol 12 (4) ◽  
pp. 1934578X1701200 ◽  
Author(s):  
Lenka Tůmová ◽  
Iva Dolečková ◽  
Helena Hendrychová ◽  
Marie Kašparová

The total arbutin content in the leaves of all the studied Bergenia plants ( B. crassifolia, B. ciliata and B. x ornata) was determined. The highest values of the arbutin content have been established for B. crassifolia (58.9 ± 0.7 mg.g−1 DW) and B. x ornata (51.0 ± 1.21 mg.g−1 DW), and the lowest for B. ciliata (5.9 ± 0.6 mg.g−1 DW). Arbutin concentration in the Bergenia leaves was the lowest in spring, in the autumn, on the contrary it increased. All the tested aqueous extracts caused a dose-dependent increase in diphenolase activity of fungal tyrosinase in a similar way as arbutin. On the other hand, all the ethanol extracts inhibited the diphenolase activity of tyrosinase.


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