Loss of coral reef growth capacity to track future increases in sea level

Water-depths above coral reefs is predicted to increase due to global sea-level rise (SLR). As ecological degradation inhibits the vertical accretion of coral reefs, it is likely that coastal wave exposure will increase but there currently exists a lack of data in projections concerning local rates of reef growth and local SLR. In this study we have aggregated ecological data of more than 200 tropical western Atlantic and Indian Ocean reefs and calculated their vertical growth which we have then compared with recent and projected rates of SLR across different Representative Concentration Pathway (RCP) scenarios. While many reefs currently show vertical growth that would be sufficient to keep-up with recent historic SLR, future projections under scenario RCP4.5 reveal that without substantial ecological recovery many reefs will not have the capacity to track SLR. Under RCP8.5, we predict that mean water depth will increase by over half a metre by 2100 across the majority of reefs. We found that coral cover strongly predicted whether a reef could track SLR, but that the majority of reefs had coral cover significantly lower than that required to prevent reef submergence. To limit reef submergence, and thus the impacts of waves and storms on adjacent coasts, climate mitigation and local impacts that reduce coral cover (e.g., local pollution and physical damage through development land reclamation) will be necessary

Effect of Land-based Pollution on Central Java Coral Reefs

Land-based pollution has severely damaged nearshore corals reefs in the Jepara area, Central Java. Effect described here include reduced coral cover and diversity, high coral mortality, reduced reef habitat complexity, and increased bioerosion intensity, compared to reference reefs in the Karimunjawa Islands National Marine Park, Central Java. Furthermore, the polluted reefs have negative net carbonate production indicating net reef erosion. Reef health parametres based on coral cover and diversity and on net carbonate production are inversely correlated with chlorophyll A concentration, suggesting eutrophication of coastal waters as a key agent of reef degradation. Untreated sewage dumping, agricultural runoff, and aquacultural effluent all contribute to nearshore eutrophication in Central Java, but it is not possible from this study to determine which of these types of land-based pollution is most responsible for degradation of Central Java reefs. Efforts to restore the condition of degraded reefs must begin with controlling sources of land-based pollution

Bioerosion of Live Massive Corals and Branching Coral Rubble on Indonesian Coral Reefs

The degree of bioerosion of live massive corals and rubble from branching corals were measured on nine reefs from two regions of Indonesia: the Java Sea and Ambon. Bioerosion in massive corals was measured by collecting live corals, cutting and X-raying slabs, and measuring the cross-sectional area removed from each slab by the various bioeroding organisms. A technique analysing branching coral rubble was developed and similarly used to evaluate the degree of bioerosion on the reefs. This rubble technique has potential advantages over the massive coral technique since it does not require the expense and technical expertise of making and analysing X-rays, nor does it require the destruction of living coral heads. The effectiveness of this rubble technique is evaluated here. Levels of bioerosion in massive coral heads and rubble from branching corals are each compared with environmental variables and health parameters of the nine reefs. Overall, both techniques showed that bioerosion levels were positively correlated with environmental variables indicative of eutrophication. Bioerosion of live massive corals and of branching coral rubble were positively correlated. At the Ambon sites, where the eutrophication levels differ only slightly compared to the Java sites, bioerosion in coral rubble was a more sensitive indicator of eutrophication stress than bioerosion measured from massive coral heads. The rubble technique we outline is a useful rapid reef assessment technique that could be a valuable contribution to the ‘reef survey toolbox'

Local ecological knowledge and multidisciplinary approach lead to discovery of hidden biodiversity in the deep ocean of Labrador, Canada

International commitments to preserve global biodiversity target the protection of 30% of marine habitats by 2030. The lack of even basic knowledge of many marine areas (e.g., deep oceans) combined with short timelines require integrative knowledge and multidisciplinary techniques to be used to efficiently identify areas worthy of protection. Here we outline a case study of the discovery of the Makkovik Hanging Gardens found in a deep-water trough in coastal Labrador, Canada. The area is of ecological significance because it supports high densities of vulnerable marine ecosystem indicator taxa, including the gorgonian coral Primnoa resedaeformis on portions of its vertical submarine walls. This study illustrates the exploratory process initiated by Nunatsiavut, which integrated local knowledge, scientific models, and a variety of technologies (such as remotely operated vehicles and multibeam sonar) to discover deep-water hidden biodiversity toward the advancement of both local Indigenous and global conservation goals