Publications by authors named "Nils E Asp"

Article Synopsis
  • - The study examines the microbial diversity in sediments from Airo Lake, a floodplain lake in the Amazon, using metagenomics and biogeochemical analysis to understand the impact of the Negro River on the lake's environment.
  • - Three sediment layers were analyzed, revealing distinct microbiomes: older, deeper sediments had a higher abundance of specific bacteria like Burkholderia, while more recent layers contained different microbes like Thermococcus, indicating changes over time.
  • - A significant number of metagenome-assembled genomes (MAGs) identified in the older strata are linked to unknown taxa, suggesting potential new species, and show enrichment in sulfur cycle genes, highlighting the complexity of microbial interactions in this ecosystem.
View Article and Find Full Text PDF
Article Synopsis
  • Sponges have co-evolved with microbes for over 400 million years, classified into Low Microbial Abundance (LMA) and High Microbial Abundance (HMA) based on their microbial content.
  • This study investigates sponges from the Great Amazon Reef System (GARS), revealing that LMA sponges derive nutrition from the Amazon River Plume, while HMA sponges maintain specialized symbiotic microbes.
  • Findings indicate distinct microbial communities in LMA and HMA sponges, with LMA sponges showing higher phage abundance and HMA sponges exhibiting mechanisms for phage defense, highlighting their ecological roles and interactions in nutrient cycling.
View Article and Find Full Text PDF

Sediment transfer from land to ocean begins in coastal settings and, for large rivers such as the Amazon, has dramatic impacts over thousands of kilometers covering diverse environmental conditions. In the relatively natural Amazon tidal river, combinations of fluvial and marine processes transition toward the ocean, affecting the transport and accumulation of sediment in floodplains and tributary mouths. The enormous discharge of Amazon fresh water causes estuarine processes to occur on the continental shelf, where much sediment accumulation creates a large clinoform structure and where additional sediment accumulates along its shoreward boundary in tidal flats and mangrove forests.

View Article and Find Full Text PDF

The Great Amazon Reef (GARS) is an extensive mesophotic reef ecosystem between Brazil and the Caribbean. Despite being considered as one of the most important mesophotic reef ecosystems of the South Atlantic, recent criticism on the existence of a living reef in the Amazon River mouth was raised by some scientists and politicians. The region is coveted for large-scale projects for oil and gas exploration.

View Article and Find Full Text PDF

The cephalopod fauna of the southwestern Atlantic is especially poorly-known because sampling is mostly limited to commercial net-fishing operations that are relatively inefficient at obtaining cephalopods associated with complex benthic substrates. Cephalopods have been identified in the diets of many large marine species but, as few hard structures survive digestion in most cases, the identification of ingested specimens to species level is often impossible. Samples can be identified by molecular techniques like barcoding and for cephalopods, mitochondrial 16S and COI genes have proven to be useful diagnostic markers for this purpose.

View Article and Find Full Text PDF

Although recent years have seen an increase in genetic analyses that identify new species of cephalopods and phylogeographic patterns, the loliginid squid of South America remain one of the least studied groups. The suggestion that Doryteuthis plei may represent distinct lineages within its extensive distribution along the western Atlantic coasts from Cape Hatteras, USA (36°N) to northern Argentina (35°S) is consistent with significant variation in a number of environmental variables along this range including in both temperature and salinity. In the present study D.

View Article and Find Full Text PDF
Article Synopsis
  • Large rivers, like the Amazon, significantly disrupt reef distributions on tropical shelves by affecting salinity, pH, light penetration, and sedimentation over a large area of the North Atlantic.
  • Despite these harsh conditions, a complex carbonate system thrives off the Amazon's mouth, characterized by unique hard-bottom structures, originating from sedimentation during low sea levels and continuing in certain areas.
  • These carbonate structures support diverse marine life, including sponges and filter feeders, and act as a connectivity corridor for reef-associated species, offering insights into how tropical reefs can adapt to challenging conditions, which are becoming more common globally.
View Article and Find Full Text PDF

The Amazonian coast has several unique geological characteristics resulting from the interaction between drainage pattern of the Amazon River and the Atlantic Ocean. It is one of the most extensive and sedimentologically dynamic regions of the world, with a large number of continental islands mostly formed less than 10,000 years ago. The natural distribution of the cane toad (Rhinella marina), one of the world's most successful invasive species, in this complex Amazonian system provides an intriguing model for the investigation of the effects of isolation or the combined effects of isolation and habitat dynamic changes on patterns of genetic variability and population differentiation.

View Article and Find Full Text PDF