Ranking 67 Florida Reefs for Survival of Acropora cervicornis Outplants

Over the past three decades, coral populations have declined across the tropical and subtropical oceans because of thermal stress, coral diseases, and pollution. Restoration programs are currently attempting to re-establish depauperate coral populations along the Florida reef tract. We took an integrated Bayesian approach to determine which Florida reefs ranked highest based on the survival of outplanted colonies of Acropora cervicornis from 2012 to 2018. Survival of A. cervicornis outplants was highly variable in the upper Florida Keys with some reefs showing the highest likelihood of survival (e.g., North Dry Rocks, Carysfort, Key Largo Dry Rocks, and Conch Reef), whereas some adjacent reefs showed the lowest likelihood of survival (e.g., an Unnamed Reef, Pickles Reef, and U47 Patch Reef). Similarly, survival was highly variable in the middle and lower Florida Keys and in the Broward-Miami subregions. Survival was high and less variable in Biscayne Bay and low and less variable in the Marquesas subregions. The reefs that ranked lowest for outplant survival were exposed to high wave energy. Partitioning out the spatial effects of reefs and subregions from the model, we detected spatial latent effects of low survival that were most evident in the middle and the upper Florida Keys, particularly between 2015 and 2017. The overall high spatial and temporal variability in survival among adjacent reefs highlights a need to outplant nursery-reared colonies strategically, in order to optimize coral-population recovery efforts in Florida.

Fossil molluscan fauna reflects zonation of a Late Pleistocene reef of the Red Sea

<p>Many studies focus on modern coral reefs and their associated invertebrate fauna, but not much is known about the paleoecology and diversity of molluscs of Late Pleistocene coral reefs, which were formed during the last interglacial MIS5e. This study is investigating the molluscan assemblage of a Late Pleistocene coral reef in southern Egypt, at the locality Sharm El Luli, in the area of Marsa Alam. The locality is characterized by a variety of reef- and reef associated habitats, including a reef flat, reef slope, a patch reef, and soft bottoms of a lagoon and in the backreef area. We quantitatively and qualitatively sampled 10 sites with a total of 79 samples and collected 2126 shells, which belong to 177 taxa, mostly identified to the species level.   Most taxa were found with the qualitative sampling approach. The most abundant bivalves taxon was the epifaunal, encrusting <em>Chama </em>spp., the most abundant gastropod species was the cerithiid <em>Rhinoclavis vertagus</em>. Regarding the life habitats most bivalve species are infaunal filter feeders, while most gastropods are epifaunal carnivores.    Alpha diversity is highest in the coral patch and in the upper reef region, which implies the reef slope, the reef flat as well as the transition between reef slope and the lagoon. Preliminary statistical results suggest a division in coral-patch, lagoon and backreef as well as a cluster of upper-reef habitats. From these two broad environments can be distinguished: hard bottoms associated to reefs and reef-associated soft bottom environments. The former are best characterized by encrusting taxa such as <em>Chama </em>spp. and <em>Spondylus </em>spp., and by <em>Tridacna maxima</em> and <em>Perigylypta </em>spp., which are well-known reef associates. Gastropods in this environment are predatory conids and cypraeids. All of these species live on - or occur cryptically in - structured hard bottoms. Reef associated-soft bottom environments are best characterized by infauna, such as the tellinid <em>Quidinipagus palatam</em> and the lucinids <em>Anodontia kora</em> and <em>Pillucina vietnamica</em>. Furthermore, many soft bottom gastropod species such as the strombid <em>Gibberulus gibberulus albus</em>, the cerithiid <em>Rhinoclavis vertagus</em>, both with an herbivorous diet, and the nassariid <em>Nassarius fenistratus</em>, a scavenger, can be found here.  A comparison with modern datasets from the Red Sea indicates strong similarities in faunal composition and habitat diversity between fossil and recent reefs.  Furthermore, our preliminary results suggest that Late Pleistocene molluscan assemblages can aid in reconstruction of associated fossil reef habitats. </p>

The mineralogic and isotopic fingerprint of equatorial carbonates: Kepulauan Seribu, Indonesia

Kepulauan Seribu is an isolated patch reef complex situated in the Java Sea (Indonesia) and is a typical example for a humid, equatorial carbonate system. We investigate the mineralogical and isotopic fingerprint of Panggang, one of the reef platforms of Kepulauan Seribu, to evaluate differences to other carbonate systems, using isotope in combination with XRD and SEM analysis. A characteristic property of shallow water (< 20 m) sediments from Kepulauan Seribu is their increased LMC content (~ 10%) derived from some genera of rotaliid foraminifers and bivalves. The relative abundance of these faunal elements in shallow waters might be related to at least temporary turbid conditions caused by sediment-laden river runoff. This influence is also evidenced by the presence of low amounts of siliciclastic minerals below the regional wave base. Kepulauan Seribu carbonates are characterized by very low δ13C and δ18O values. This is related to the isotopically depleted riverine input. The δ13CDIC in riverine water is reduced by the contribution of 12C from riverside mangroves. Deep atmospheric convection and intensive rains contribute 18O-depleted freshwater in the river catchments, finally reducing salinity in the Java Sea. The depleted δ13C signature in carbonates is further enhanced by the lack of green algae and inorganic carbonates and abundance of coral debris. Low δ18O values in carbonates are favored by the high water temperatures in the equatorial setting. Since equatorial carbonates in SE Asia, including the Java Sea, are typically influenced by high turbidity and/or river runoff, the observed distinctively low isotope values likely are characteristic for equatorial carbonate systems in the region.

Investigating sea urchin densities critical to macroalgal control on degraded coral reefs

Summary There is an assumption that tropical sea urchins are macroalgal grazers with the ability to control macroalgal expansion on degraded coral reefs. We surveyed abundances of Echinothrix calamaris, an urchin species common in the western Indian Ocean on 21 reefs of the inner Seychelles and predicted their density using habitat predictors in a modelling approach. Urchin densities were greatest on patch reef habitat types and declined with increasing macroalgal cover. Next, we experimentally investigated the macroalgae-urchin relationship by penning two sea urchin densities on macroalgal fields. Over six weeks, the highest density treatment (4.44 urchins m−2) cleared 13% of macroalgal cover. This moderate impact leads us to conclude that controlling macroalgal expansion is not likely to be one of the main functions of E. calamaris in the inner Seychelles given the current densities we found in our surveys (mean: 0.02 urchins m−2, maximum: 0.16 urchins m−2).

Struktur Komunitas Ikan Karang dan Tutupan Karang pada Terumbu Buatan Artificial Patch Reef (APR)

Artificial Patch Reef (APR) have been applied as a new method for Biodiversity Conservation Program at Panjang Island, Jepara since 2015. Previous study suggested that design and location of artificial reefs installation affected to abundance of reef fishes, associated with the artificial reef. This study aims to investigated community structure of reef fishes associated to artificial patch reef comparing to reef fishes in nearby natural reefs. Assessment of coral reef condition on two habitats were conducted on July 2019, after 4 years deployment. The results show that artificial patch reefs with a percentage of live coral cover are less than half of natural coral reefs, and have succeeded in increasing the abundance of reef fish with nearly the same density and community structure resembling reef fish in natural coral reefs. The similarity in community structure of the two habitats is probably due to the similarity in habitat type and morphology of the hard corals. The results indicate that Artificial Patch Reef (APR) reefs have increased the coral cover of Acropora branching and resulted in increased reef fish abundance which is compatible with reef fish communities associated with natural coral reefs around it. Aplikasi metode baru terumbu buatan Artificial patch Reef (APR) pada Program Konservasi Bioiversitas Pulau Panjang, Jepara telah dilakukan sejak 2015. Hasil studi menunjukkan bahwa pemilihan desain dan lokasi pemasangan terumbu buatan yang tepat akan meningkatkan kelimpahan ikan karang. Tujuan penelitian ini adalah untuk mengetahui keberhasilan penerapan terumbu buatan APR melalui kelimpahan ikan karang yang berasosiasi pada terumbu buatan dan terumbu karang alami di sekitarnya. Penilaian kondisi terumbu karang tersebut telah dilakukan pada Juli 2019 setelah 4 (empat) tahun pemasangan terumbu buatan. Hasil studi menunjukkan bahwa terumbu buatan dengan persentase tutupan karang hidup lebih kecil, separuhnya dari tutupan pada terumbu karang alami telah berhasil meningkatkan kelimpahan ikan karang dengan densitas hampir sama dan struktur komunitasnya menyerupai ikan karang yang berasosiasi dengan terumbu karang alami. Kesamaan struktur komunitas kedua habitat kemungkinan akibat kesamaan tipe habitat dan morfologi karang keras penyusunya. Hasil ini mengindikasikan bahwa terumbu buatan Artificial patch Reef (APR) telah meningkatkan tutupan karang bercabang Acropora dan berakibat terhadap meningkatnya kelimpahan ikan karang yang sesuai dengan komunitas ikan karang yang berasosiasi dengan terumbu karang alami di sekitarnya.

Phenotypic variation in two widespread Caribbean corals — Porites astreoides and P. divaricata — between mangrove and lagoon habitats

ABSTRACTAs coral reefs experience dramatic declines in coral cover throughout the tropics, there is an urgent need to understand the role that non-reef habitats such as mangroves play in the ecological niche of corals. Mangrove habitats present a challenge to reef-dwelling corals as they can differ dramatically from adjacent reef habitats with respect to key environmental parameters such as temperature and light. As variation in temperature and light within reef habitats is known to drive intraspecific differences in coral phenotype, we hypothesized that coral species which can exploit both reef and mangrove habitats will exhibit predictable differences in phenotype between habitats. To investigate how intraspecific variation, driven by either local adaptation or phenotypic plasticity, might enable particular coral species to exploit these two qualitatively different habitat types, we compared the phenotypes of two widespread Caribbean corals — Porites divaricata and P. astreoides— in mangrove versus lagoon habitats on Turneffe Atoll, Belize. We document significant differences in colony size, color, structural complexity, and corallite morphology between habitats. In every instance, the difference between mangrove and lagoon corals was consistent in P. divaricata and P. astreoides. This study is the first to document intraspecific phenotypic diversity in corals occupying mangrove versus patch-reef habitats, and it provides a foundation for understanding why some “reef coral” species can exploit mangroves, while others cannot.

Metabolomic signatures of coral bleaching history

Coral bleaching, a process where corals expel their photosynthetic symbionts, has a profound impact on the health and function of coral reefs. As global ocean temperatures continue to rise, bleaching poses the greatest threat to coral reef ecosystems. Here, untargeted metabolomics was used to analyze the biochemicals in pairs of adjacent corals from a patch reef in Kāne‘ohe Bay, Hawai‘i, where one colony in the pair bleached (in 2015) and recovered while the other did not bleach. There was a strong metabolomic signature of prior bleaching history four years after recovery found in both the host and its algal symbionts. Machine learning analysis determined that the strongest metabolite drivers of the difference in bleaching phenotype were a group of betaine lipids. Those with saturated fatty acids were significantly enriched in thermally tolerant corals and those with longer, unsaturated and diacyl forms were enriched in historically bleached corals. Host immune response molecules, Lyso-PAF and PAF, were also altered by bleaching history and were strongly correlated with symbiont community and algal-derived metabolites suggesting a role of coral immune modulation in symbiont choice and bleaching response. To validate these findings, we tested a separate in situ set of corals and were able to predict the bleaching phenotype with 100% accuracy. Furthermore, corals subjected to an experimental temperature stress had strong phenotype-specific responses in all components of the holobiont, which served to further increase the differences between historical bleaching phenotypes. Thus, we show that natural bleaching susceptibility is simultaneously manifested in the biochemistry of the coral animal and the algal symbiont and that this bleaching history results in different physiological responses to temperature stress. This work provides insight into the biochemical mechanisms involved in coral bleaching and presents a valuable new tool for resilience-based reef restoration.

Coral transplantation on a multilevel substrate of Artificial Patch Reefs: effect of fixing methods on the growth rate of two Acropora species

Munasik, Sabdono A, Assyfa AN, Wijayanti DP, Sugiyanto, Irwani, Pribadi R. 2020. Coral transplantation on a multilevel substrate of Artificial Patch Reefs: effect of fixing methods on the growth rate of two Acropora species. Biodiversitas 21: 1816-1822. Branching Acropora is generally used in coral transplantation to rehabilitate coral reefs. However, these corals are sensitive to environmental changes. Artificial Patch Reef (APR) is an artificial structure that provides a multilevel hard substrate. The purpose of the study was to investigate the effectiveness of the APR structure to facilitate the growth and survival of Acropora branching. Two species Acropora aspera and Acropora copiosa were transplanted vertically and horizontally on a modular concrete block in different levels of APR situated in the shallow reef of Panjang Island, Central Java. The results showed that the coral growth rate varied from 96.7 to 346.9 cm3/month, while survival ranged from 30 to 100% after 8 months. Lower survival rate mostly was found in the upper level of APR. The statistical analyses showed that the growth rate of A. copiosa fragment was significantly higher than that of A. aspera (p<0.05). Moreover, there were also significant differences in the treatments of transplantation method (p<0.05) to enhance coral growth. However, multilevel substrates were not significantly influenced by coral growth. This study suggested that A. copiosa which has high-level complexity in branching pattern will be selected to apply in shallow reef rehabilitation with transplanted vertically.

Rhodolith holobionts are not sources of fixed nitrogen in a northeastern Gulf of Mexico patch reef

Rhodoliths provide numerous benefits to coastal ecosystems and help support high biodiversity. No study, however, has explored rhodoliths that occupy northeastern Gulf of Mexico patch reefs, and their contributions to local ecosystem function remain uncharacterized. Here, we employed the acetylene reduction assay to assess nitrogen fixation capability in rhodolith holobionts (Lithothamnion spp.; Rhodophyta), sediment, and surrounding seawater from a subtropical patch reef ecosystem in the northeastern Gulf of Mexico. We found no evidence for nitrogenase activity in rhodolith holobionts or seawater from our study site, while nitrogenase activity in sediment underlying rhodoliths was approximately equivalent to a nitrogen fixation rate of 0.521 (SD 0.087) nmol N2 g dry mass−1 hr−1. Our results suggest that rhodoliths in the northeastern Gulf of Mexico rely on sources of nitrogen from sediment nitrogen fixation or water column nutrient availability rather than the activity of symbiotic diazotrophic microorganisms. Functional analyses recognizing rhodoliths as holobionts warrant further investigation to better understand the ecology of rhodoliths.