Distinct histomorphology for growth arrest and digitate outgrowth in cultivated Haliclona sp. (Porifera: Demospongiae).

The use of sponges in biotechnological processes is limited by the supply problem, and sponge biomass production is becoming a current topic of research. The distinction between characteristics for growth and growth arrest is also important for environmental monitoring. In this study, we analyze the morphology of the digitate outgrowths from the sponge Haliclona sp. The sponge Haliclona sp. was successfully cultivated for 14 months in a closed system. The morphological characterization of growth arrest was performed after submitting explants to starvation-stress for approximately 2 weeks, to correlate morphology with growth and growth arrest. The digitate outgrowth showed three distinct regions: mature (MR), transition (TR) and immature (IR). Our data suggest a growth developmental program, with collagen fascicles guiding axial growth in IR, followed by progressive development of choanocyte chambers and large aquiferous systems at the more mature proximal region (choanosome). The intercalation of choanocyte chambers and small aquiferous systems inside collagen fascicles previously originated at the IR region can be responsible for thickening expansion and conversion of the collagen fascicles into columnar choanosome in MR. The growth arrest after starvation-stress assay showed morphological changes in the IR corroborating collagen in the extreme tip of the digitate outgrowth as an important role in guiding of axial growth of Haliclona sp. The identification of distinct morphologies for growth and growth arrest suggest a growth developmental program, and these data could be useful for further investigations addressing sponge biomass gain and environmental monitoring.

An extensive reef system at the Amazon River mouth.

Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 × 10(6)-km(2) plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume's eastward retroflection, conditions the existence of this extensive (~9500 km(2)) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth-ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes.

Niche distribution and influence of environmental parameters in marine microbial communities: a systematic review.

Associations between microorganisms occur extensively throughout Earth's oceans. Understanding how microbial communities are assembled and how the presence or absence of species is related to that of others are central goals of microbial ecology. Here, we investigate co-occurrence associations between marine prokaryotes by combining 180 new and publicly available metagenomic datasets from different oceans in a large-scale meta-analysis. A co-occurrence network was created by calculating correlation scores between the abundances of microorganisms in metagenomes. A total of 1,906 correlations amongst 297 organisms were detected, segregating them into 11 major groups that occupy distinct ecological niches. Additionally, by analyzing the oceanographic parameters measured for a selected number of sampling sites, we characterized the influence of environmental variables over each of these 11 groups. Clustering organisms into groups of taxa that have similar ecology, allowed the detection of several significant correlations that could not be observed for the taxa individually.