Publications by authors named "Yusuf Khaled"

Coral reefs may experience lower pH values as a result of ocean acidification (OA), which has negative consequences, particularly for calcifying organisms. Thus far, the effects of this global factor have been mainly investigated on hard corals, while the effects on soft corals remain relatively understudied. We therefore carried out a manipulative aquarium experiment for 21 days to study the response of the widespread pulsating soft coral Xenia umbellata to simulated OA conditions.

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Both global and local factors affect coral reefs worldwide, sometimes simultaneously. An interplay of these factors can lead to phase shifts from hard coral dominance to algae or other invertebrates, particularly soft corals. However, most studies have targeted the effects of single factors, leaving pronounced knowledge gaps regarding the effects of combined factors on soft corals.

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Many coastal ecosystems, such as coral reefs and seagrass meadows, currently experience overgrowth by fleshy algae due to the interplay of local and global stressors. This is usually accompanied by strong decreases in habitat complexity and biodiversity. Recently, persistent, mat-forming fleshy red algae, previously described for the Black Sea and several Atlantic locations, have also been observed in the Mediterranean.

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Recent research suggests that nitrogen (N) cycling microbes are important for coral holobiont functioning. In particular, coral holobionts may acquire bioavailable N via prokaryotic dinitrogen (N) fixation or remove excess N via denitrification activity. However, our understanding of environmental drivers on these processes remains limited.

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Coral reefs experience phase shifts from coral- to algae-dominated benthic communities, which could affect the interplay between processes introducing and removing bioavailable nitrogen. However, the magnitude of such processes, i.e.

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Nitrogen cycling in coral reefs may be affected by nutrient availability, but knowledge about concentration-dependent thresholds that modulate dinitrogen fixation and denitrification is missing. We determined the effects of different nitrate concentrations (ambient, 1, 5, 10 μM nitrate addition) on both processes under two light scenarios (i.e.

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Article Synopsis
  • The study investigates how nutrient pollution affects coral and algae-dominated reef patches in the central Red Sea over two months.
  • Nutrient enrichment led to a significant increase in productivity and a shift to dissolution in algae-dominated communities, while coral communities remained unaffected.
  • These changes suggest that nutrient pollution could worsen the impacts of species shifts, harming critical ecosystem services and leading to habitat loss in coral reefs.
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Article Synopsis
  • The study investigates how increased nitrogen levels affect major benthic groups in a central Red Sea coral reef, focusing on hard corals, soft corals, turf algae, and reef sands.
  • Over an 8-week period, researchers used a fertilizer to increase dissolved inorganic nitrogen (DIN) concentrations by three times the normal level and measured nitrogen and carbon content in these organisms.
  • The results showed that turf algae benefited the most from nitrogen addition, absorbing the highest levels, which could give them a competitive edge over hard corals, highlighting the need for better coastal management to address nitrogen enrichment.
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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Denitrification may potentially alleviate excess nitrogen (N) availability in coral holobionts to maintain a favourable N to phosphorous ratio in the coral tissue. However, little is known about the abundance and activity of denitrifiers in the coral holobiont. The present study used the nirS marker gene as a proxy for denitrification potential along with measurements of denitrification rates in a comparative coral taxonomic framework from the Red Sea: Acropora hemprichii, Millepora dichotoma, and Pleuractis granulosa.

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Background: Despite the advances in breast cancer care, inflammatory breast cancer (IBC) has a poor prognosis. The purpose of this study was to determine the efficacy of high-dose chemotherapy (HDCT) with thiotepa, mitoxantrone and carboplatin (TMJ regimen) in women with TNM stage IIIB IBC.

Patients And Methods: Between 1991 and 1998, twenty-eight patients with stage IIIB IBC underwent an autologous stem cell transplant after undergoing chemotherapy, surgery and/or radiation.

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