Physiologic and metagenomic attributes of the rhodoliths forming the largest CaCO3 bed in the South Atlantic Ocean

Rhodoliths are free-living coralline algae (Rhodophyta, Corallinales) that are ecologically important for the functioning of marine environments. They form extensive beds distributed worldwide, providing a habitat and nursery for benthic organisms and space for fisheries, and are an important source of calcium carbonate. The Abrolhos Bank, off eastern Brazil, harbors the world''s largest continuous rhodolith bed (of ∼21 000 km²) and has one of the largest marine CaCO₃ deposits (producing 25 megatons of CaCO₃ per year). Nevertheless, there is a lack of information about the microbial diversity, photosynthetic potential and ecological interactions within the rhodolith holobiont. Herein, we performed an ecophysiologic and metagenomic analysis of the Abrolhos rhodoliths to understand their microbial composition and functional components. Rhodoliths contained a specific microbiome that displayed a significant enrichment in aerobic ammonia-oxidizing betaproteobacteria and dissimilative sulfate-reducing deltaproteobacteria. We also observed a significant contribution of bacterial guilds (that is, photolithoautotrophs, anaerobic heterotrophs, sulfide oxidizers, anoxygenic phototrophs and methanogens) in the rhodolith metagenome, suggested to have important roles in biomineralization. The increased hits in aromatic compounds, fatty acid and secondary metabolism subsystems hint at an important chemically mediated interaction in which a functional job partition among eukaryal, archaeal and bacterial groups allows the rhodolith holobiont to thrive in the global ocean. High rates of photosynthesis were measured for Abrolhos rhodoliths (52.16 μmol carbon m⁻²s⁻¹), allowing the entire Abrolhos rhodolith bed to produce 5.65 × 10⁵ tons C per day. This estimate illustrates the great importance of the Abrolhos rhodolith beds for dissolved carbon production in the South Atlantic Ocean.     

Diversity of isopods (Crustacea): new data from the Arctic and Atlantic Oceans

New data on the diversity pattern of isopods (Crustacea) from the northern most part of the North Atlantic and the Arctic Oceans is presented. The pattern of diversity with depth is similar at depths <1000m, but differs considerably below about 1000m. In the Arctic the diversity of isopods (expressed both as numbers of species per sled and expected number of species) increased with increased depth to a maximum at depths of about 320 to 1100m, but then declined towards deeper waters. There was a significant increase in numbers per sled and in the expected number of species with increased depth in the northernmost part of the North Atlantic Ocean. Additionally, changes occurred in the relative composition of the shallow and deep water fauna, with asellote isopods being relatively larger part of the isopod fauna in the Arctic than in the northern most part of the North Atlantic. This indicates major faunistic changes occurring at the Greenland-Iceland-Faeroe Ridge, possibly caused by rapid changes in the temperature. Furthermore, that the low diversity of the Arctic deep-sea is a regional phenomenon, and not a part of a large scale latitudinal pattern in the North Atlantic.     

Artificial habitats and the restoration of degraded marine ecosystems and fisheries

Artificial habitats in marine ecosystems are employed on a limited basis to restore degraded natural habitats and fisheries, and more extensively for a broader variety of purposes including biological conservation and enhancement as well as social and economic development. Included in the aims of human-made habitats classified as artificial reefs are: Aquaculture/marine ranching; promotion of biodiversity; mitigation of environmental damage; enhancement of recreational scuba diving; eco-tourism development; expansion of recreational fishing; artisanal and commercial fisheries production; protection of benthic habitats against illegal trawling; and research. Structures often are fabricated according to anticipated physical influences or life history requirements of individual species. For example, many of the world’s largest reefs have been deployed as part of a national fisheries program in Japan, where large steel and concrete frameworks have been carefully designed to withstand strong ocean currents. In addition, the differing ecological needs of porgy and sea bass for shelter guided the design of the Box Reef in Korea as a device to enhance productivity of marine ranching. The effect of these and other structures on fisheries catch is positive. But caution must be exercised to avoid using reefs simply as fishing devices to heavily exploit species attracted to them. No worldwide database for artificial habitats exists.The challenge to any ecological restoration effort is to define the condition or possibly even the historic baseline to which the system will be restored; in other words, to answer the question: “Restoration to what?” Examples of aquatic ecosystem restoration from Hong Kong (fisheries), the Pacific Ocean (kelp beds), Chesapeake Bay (oysters) and the Atlantic Ocean (coral reefs) are discussed. The degree to which these four situations consider or can approach a baseline is indicated and compared (e.g., four plants per 100 m² are proposed in one project). Measurement of performance is a key factor in restoration planning. These situations also are considered for the ecosystem and fishery contexts in which they are conducted. All use ecological data as a basis for physical design of restoration structures. The use of experimental, pilot and modeling practices is indicated.A context for the young field of marine restoration is provided by reviewing major factors in ecosystem degradation, such as high stress on 70% of commercially valuable fishes worldwide. Examples of habitat disruption include an extensive hypoxic/anoxic zone in the Gulf of Mexico and nutrient and contaminant burdens in the North Sea. Principles of ecological restoration are summarized, from planning through to evaluation. Alternate approaches to facilitate ecological recovery include land-use and ecosystem management and determining levels of human population, consumption and pollution.     

What can metazoan parasites reveal about the taxonomy of Scomber japonicus Houttuyn in the coast of South America and Madeira Islands?

The metazoan parasites of four populations of the chub mackerel Scomber japonicus were analysed from two localities in the Atlantic Ocean (Madeira Islands, Portugal, and Rio de Janeiro, Brazil) and two localities in the Pacific Ocean (Callao, Peru, and Antofagasta, Chile), collected during 2002 and 2003. A total of 373 fish specimens were studied and 34 metazoan parasite species were obtained. Parasites identified from the populations of chub mackerel studied could be separated into three categories: parasites with a wide distribution, present in the Pacific and Atlantic, parasites proper of the Pacific Ocean and parasites proper of the Atlantic Ocean. The analyses of some highly specific parasites of the genus Scomber ( i.e. monogeneans of the genus Kuhnia and didymozoid digeneans) strongly suggest the need for a revision of the taxonomic status of chub mackerels from the Atlantic and Pacific coast of America. The results demonstrated the usefulness of parasites as adequate tools to clarify the taxonomic status of their hosts.     

First direct documentation of associations of Ceratolithus cristatus ceratoliths, hoop-coccoliths and Neosphaera coccolithomorpha planoliths

Study of plankton sample from the northeast Atlantic has revealed an exceptional specimen of Ceratolithus cristatus. This consists of a rostratus-type ceratolith surrounded by a collapsed coccosphere of delicate hoop-coccoliths and a partial outer collapsed coccosphere of nishidae-type planoliths. This provides the final direct evidence needed to support the earlier hypothesis that these three calcareous structures are all provided by the single species Ceratolithus cristatus. It appears likely that this species has a complex life-cycle.