Physiological response of Symbiodiniaceae to thermal stress: Reactive oxygen species, photosynthesis, and relative cell size.

This study investigates the physiological response to heat stress of three genetically different Symbiodiniaceae strains isolated from the scleractinian coral Mussismilia braziliensis, endemic of the Abrolhos Bank, Brazil. Cultures of two Symbiodinium sp. and one Cladocopium sp. were exposed to a stepwise increase in temperature (2°C every second day) ranging from 26°C (modal temperature in Abrolhos) to 32°C (just above the maximum temperature registered in Abrolhos during the third global bleaching event-TGBE). After the cultures reached their final testing temperature, reactive oxygen species (ROS) production, single cell attributes (relative cell size and chlorophyll fluorescence), and photosynthetic efficiency (effective (Y(II)) and maximum (Fv/Fm) quantum yields) were measured within 4 h and 72 h. Non-photochemical coefficient (NPQ) was estimated based on fluorescence values. Population average ROS production was variable across strains and exposure times, reaching up a 2-fold increase at 32°C in one of the Symbiodinium sp. strains. A marked intrapopulation difference was observed in ROS production, with 5 to 25% of the cells producing up to 10 times more than the population average, highlighting the importance of single cell approaches to assess population physiology. Average cell size increases at higher temperatures, likely resulting from cell cycle arrest, whereas chlorophyll fluorescence decreased, especially in 4 h, indicating a photoacclimation response. The conditions tested do not seem to have elicited loss of photosynthetic efficiency nor the activation of non-photochemical mechanisms in the cells. Our results unveiled a generalized thermotolerance in three Symbiodiniaceae strains originated from Abrolhos' corals. Inter and intra-specific variability could be detected, likely reflecting the genetic differences among the strains.

First record of mating behaviour and induced parturition of the Brazilian endemic Lutz's stingray Hypanus berthalutzae.

The recently described Lutz's stingray Hypanus berthalutzae is endemic to the Brazilian Province, including oceanic islands. Although it is expected to have life-history traits similar to the southern stingray H. americanus, little is known about its reproductive biology. Here we present the first observations of courtship behaviour (n = 4), copulation (n = 3) and an induced parturition of H. berthalutzae at the Fernando de Noronha Archipelago, an insular Marine Protected Area from the Equatorial Atlantic Ocean. The mating event records included (1) 'chasing/close following', (2) 'biting/precopulatory biting', (3) 'insertion/copulation' and (4) 'separation'. These results are especially relevant considering that records of reproductive behaviour in the wild are rare for elasmobranchs in general. Mating events occurred in different months, suggesting that the reproductive cycle of H. berthalutzae in this insular system is asynchronous, as observed for other stingray species in regions with favourable environmental conditions and abundant food throughout the year. The opportunistic documentation of the induced parturition allowed for direct nonlethal observation of the two pups at or near full term in late May. Although preliminary, these observations should be considered in future management plans as they provide relevant data about the life-history traits and mating behaviour of this endemic and threatened species.

Erythropodium caribaeorum (Duchassaing and Michelotti, 1860) (Cnidaria: Alcyonacea), an additional alien coral in the Southwestern Atlantic.

Invasive species may compromise biodiversity and ecosystem services, and represent a steadily growing concern for coastal marine ecosystems. The marine aquarium trade (MAT) is the source of some of the world's worst aquatic invasions, inflicting multimillion-dollar losses in infected regions. In the Southwestern Atlantic (SWA), two Indo-Pacific coral species were recently introduced as a result of the MAT and already dominate the substrate at the introduction site in Southeastern Brazil (Praia Vermelha, Angra dos Reis, Rio de Janeiro State). Herein, based on morphological and molecular evidence, we report a Caribbean native coral species likely introduced by the MAT in Praia Vermelha, Erythropodium caribaeorum (Duchassaing Michelotti 1860). While the eradication of coral species that already have a pest status in the SWA is unlikely, we propose that the eradication of the three species still contained to their introduction sites, including E. caribaeorum, is still feasible and depends on a rapid and integrated embracement of the task by core stakeholders. Priority actions for the regulation of MAT and hobbyism in Brazil are proposed.

Metagenomics of Coral Reefs Under Phase Shift and High Hydrodynamics.

Local and global stressors have affected coral reef ecosystems worldwide. Switches from coral to algal dominance states and microbialization are the major processes underlying the global decline of coral reefs. However, most of the knowledge concerning microbialization has not considered physical disturbances (e.g., typhoons, waves, and currents). Southern Japan reef systems have developed under extreme physical disturbances. Here, we present analyses of a three-year investigation on the coral reefs of Ishigaki Island that comprised benthic and fish surveys, water quality analyses, metagenomics and microbial abundance data. At the four studied sites, inorganic nutrient concentrations were high and exceeded eutrophication thresholds. The dissolved organic carbon (DOC) concentration (up to 233.3 µM) and microbial abundance (up to 2.5 × 105 cell/mL) values were relatively high. The highest vibrio counts coincided with the highest turf cover (∼55-85%) and the lowest coral cover (∼4.4-10.2%) and fish biomass (0.06 individuals/m2). Microbiome compositions were similar among all sites and were dominated by heterotrophs. Our data suggest that a synergic effect among several regional stressors are driving coral decline. In a high hydrodynamics reef environment, high algal/turf cover, stimulated by eutrophication and low fish abundance due to overfishing, promote microbialization. Together with crown-of-thorns starfish (COTS) outbreaks and possible of climate changes impacts, theses coral reefs are likely to collapse.

Carbonate Production by Benthic Communities on Shallow Coralgal Reefs of Abrolhos Bank, Brazil.

The abundance of reef builders, non-builders and the calcium carbonate produced by communities established in Calcification Accretion Units (CAUs) were determined in three Abrolhos Bank shallow reefs during the period from 2012 to 2014. In addition, the seawater temperature, the irradiance, and the amount and composition of the sediments were determined. The inner and outer reef arcs were compared. CAUs located on the inner reef shelf were under the influence of terrigenous sediments. On the outer reefs, the sediments were composed primarily of marine biogenic carbonates. The mean carbonate production in shallow reefs of Abrolhos was 579 ± 98 g m-2 y-1. The builder community was dominated by crustose coralline algae, while the non-builder community was dominated by turf. A marine heat wave was detected during the summer of 2013-2014, and the number of consecutive days with a temperature above or below the summer mean was positively correlated with the turf cover increase. The mean carbonate production of the shallow reefs of Abrolhos Bank was greater than the estimated carbonate production measured for artificial structures on several other shallow reefs of the world. The calcimass was higher than the non-calcareous mass, suggesting that the Abrolhos reefs are still in a positive carbonate production balance. Given that marine heat waves produce an increase of turf cover on the shallow reefs of the Abrolhos, a decrease in the cover represented by reef builders and shifting carbonate production are expected in the near future.

BaMBa: towards the integrated management of Brazilian marine environmental data.

A new open access database, Brazilian Marine Biodiversity (BaMBa) (https://marinebiodiversity.lncc.br), was developed in order to maintain large datasets from the Brazilian marine environment. Essentially, any environmental information can be added to BaMBa. Certified datasets obtained from integrated holistic studies, comprising physical-chemical parameters, -omics, microbiology, benthic and fish surveys can be deposited in the new database, enabling scientific, industrial and governmental policies and actions to be undertaken on marine resources. There is a significant number of databases, however BaMBa is the only integrated database resource both supported by a government initiative and exclusive for marine data. BaMBa is linked to the Information System on Brazilian Biodiversity (SiBBr, http://www.sibbr.gov.br/) and will offer opportunities for improved governance of marine resources and scientists' integration. Database URL: http://marinebiodiversity.lncc.br.