Examining the Effect of Heat Stress on Montastraea cavernosa (Linnaeus 1767) from a Mesophotic Coral Ecosystem (MCE)

Mechanisms and potential immune tradeoffs of accelerated coral growth induced by microfragmentation

Microfragmentation is the act of cutting corals into small pieces (~1 cm²) to accelerate the growth rates of corals relative to growth rates observed when maintaining larger-sized fragments. This rapid tissue and skeletal expansion technique offers great potential for supporting reef restoration, yet the biological processes and tradeoffs involved in microfragmentation-mediated accelerated growth are not well understood. Here we compared growth rates across a range of successively smaller fragment sizes in multiple genets of reef-building corals, Orbicella faveolata and Montastraea cavernosa. Our results confirm prior findings that smaller initial sizes confer accelerated growth after four months of recovery in a raceway. O. faveolata transcript levels associated with growth rate include genes encoding carbonic anhydrase and glutamic acid-rich proteins, which have been previously implicated in coral biomineralization, as well as a number of unannotated transcripts that warrant further characterization. Innate immunity enzyme activity assays and gene expression results suggest a potential tradeoff between growth rate after microfragmentation and immune investment. Microfragmentation-based restoration practices have had great success on Caribbean reefs, despite widespread mortality among wild corals due to infectious diseases. Future studies should continue to examine potential immune tradeoffs throughout the microfragmentation recovery period that may affect growout survival and disease transmission after outplanting.

Biodiversity Studies for Sustainable Lagoon: Thermophilic and Tropical Fish Species vs. Endemic Commercial Species at Mellah Lagoon (Mediterranean, Algeria)

Lagoons play an important socio-economic role and represent a precious natural heritage at risk from fishing pressure and chemical and biological pollution. Our research focused on better understanding the discrimination of fish biodiversity, the detection of non-indigenous species, and the valorization of commercial indigenous species at Mellah lagoon (Algeria). Taxonomic characterization and barcoding for all fish species and Inkscape schematic drawings for the most common species are provided. A total of 20 families and 37 species were recorded. The thermophilic species Coris julis, Thalassoma pavo, and Aphanius fasciatus and tropical species such as Gambusia holbrooki and Parablennius pilicornis were identified. Numerous Mediterranean species of socio-economic importance are highlighted, and detailed information is summarized for the lagoon’s sustainability. This short-term evaluation goes hand in hand with long-term programs documenting the interaction between indigenous and non-indigenous species in the lagoon and will allow the development of a provisional relationship model for future studies. Thermophilic and tropical species patterns in the Mellah lagoon are presented. Taken together, we provide useful data that can guide future investigations and may become a potential management tool for achieving the Sustainable Development Goals and protecting species with large socio-economic roles from potential thermal stress impact.

Stress Resistance and Adaptation of the Aquatic Invasive Species Tubastraea Coccinea (Lesson, 1829) to Climate Change and Ocean Acidification

A great number of studies published on long-term ocean warming and increased acidification have forecasted changes in regional biodiversity preempted by aquatic invasive species (AIS). The present paper is focused on invasive Tubastraea coccinea (TC), an azooxanthellate AIS coral thriving in regions of the Gulf of Mexico, which has shown an ability to invade altered habitats, including endemic Indo-Pacific T. coccinea (TCP) populations. To determine if invasive TC are more stress resistant than endemic Indo-Pacific T. coccinea (TCP), authors measured tissue loss and heat shock protein 70 (HSP70) expression, using a full factorial design, post exposure to changes in pH (7.5 and 8.1) and heat stress (31 °C and 34 °C). Overall, the mean time required for TCP to reach 50% tissue loss (LD50) was less than observed for TC by a factor of 0.45 (p < 0.0003). Increasing temperature was found to be a significant main effect (p = 0.004), decreasing the LD50 by a factor of 0.58. Increasing acidity to pH 7.5 from 8.1 did not change the sensitivity of TC to temperature; however, TCP displayed increased sensitivity at 31 °C. Increases in the relative density of HSP70 (TC) were seen at all treatment levels. Hence, TC appears more robust compared to TCP and may emerge as a new dominant coral displacing endemic populations as a consequence of climate change.