scholarly journals ENSAMBLES DE MACROALGAS SOBRE SUPERFICIES MUERTAS DE CORALES ESCLERACTINIOS (ANTHOZOA: SCLERACTINIA) EN EL ARRECIFE ORO VERDE, VERACRUZ, MÉXICO

2017 ◽  
Vol 32 (1) ◽  
pp. 11
Author(s):  
IVONNE LUNA ORTEGA ◽  
VICENCIO DE LA CRUZ FRANCISCO
Keyword(s):  
Coral Species ◽  
Taxonomic Composition ◽  
Scleractinian Corals ◽  
Porites Astreoides ◽  
Orbicella Faveolata ◽  
Ordination Analysis ◽  
Species Similarity ◽  
Filamentous Macroalgae ◽  
Algal Assemblages ◽  
Montastraea Cavernosa

Las macroalgas son abundantes en el arrecife Oro Verde, Veracruz pero, hasta ahora, se desconocía su riqueza taxonómica, y se presume que presentan asentamientos en los corales escleractinios hermatípicos. Por ello el presente trabajo investigó qué especies de corales presentaron colonizaciones algales; además, se determinó la composición taxonómica y la similitud de los ensambles de macroalgas entre las especies de corales escleractinios. Se establecieron diez puntos de muestreo de manera sistemática en el arrecife; en cada lugar de estudio se colocó un transecto de banda de 50 x 2 m para localizar y recolectar macroalgas en superficies muertas de corales escleractinios. La frecuencia de aparición de las algas se estimó con base en el total de corales estudiados, así como para cada especie coral. Para explicar similitudes y diferencias significativas de la composición de ensamblajes macroalgales entre especies de corales se aplicaron análisis de similitud y ordenación. Los corales escleractinios con ensambles de algas fueron Siderastrea siderea, Montastraea cavernosa, Pseudodiploria strigosa, Colpophylia natans, Stephanocoenia intersepta, Porites astreoides, Orbicella annularis, Orbicella faveolata. De un total de 100 colonias coralinas revisadas se determinaron 32 especies de macroalgas, las cuales están representadas en tres divisiones, 10 órdenes y 15 familias. Las macroalgas corticadas, foliosas corticadas y filamentosas fueron las más representadas en especies. Las algas de mayor frecuencia sobre los corales masivos fueron Laurencia obtusa, Amphiroa rigida y Caulerpa chemnitzia. Los corales masivos con mayor número de registros de algas fueron S. siderea (9 especies), M. cavernosa (19) y P. strigosa (17). Los ensambles algales en los corales masivos presentaron baja similitud, sin embargo no se detectaron grupos significativamente disimiles. Solamente S. siderea y M. cavernosa son ligeramente parecidos en la composición ficológica. Los resultados sugieren que los corales masivos del arrecife Oro Verde son vulnerables a la colonización de algas, pero es necesario indagar qué condiciones preceden al asentamiento algal.Macroalgal assemblages on dead surfaces of scleractinian corals (Anthozoa: Scleractinia) in the Oro Verde reef, Veracruz, MexicoBenthic macroalgae are abundant in the Oro Verde reef but their taxonomic richness was hitherto unknown and it is presumed to present settlements on the massive corals. For this reason, the present work investigated which species of massive corals show algal colonization. Also, their taxonomic composition was determined, and the similarity of the algal assemblages between species of scleractinian corals was measured. Ten sampling points were systematically established in the reef, where a transect band of 50 x 2 m at each site was placed to locate and collect algae fron the dead surfaces of scleractinian corals. The frequency of occurrence of algae species was estimated based on the total number of coral species studied, as well as on each coral species. Similarity and ordination analysis were applied in order to explain similarities and significant differences of the phycological composition among the coral species. Scleractinian corals with algal assemblages were: Siderastrea siderea, Montastraea cavernosa, Pseudodiploria strigosa, Colpophylia natans, Stephanocoenia intersepta, Porites astreoides, Orbicella annularis, Orbicella faveolata. Thirty-two species of algae were identified from a total of 100 revised coral colonies which are represented in 3 divisions, 10 orders and 15 families. The corticated, foliose corticated and filamentous macroalgae were the most represented species. The most frequent algae on massive corals were Laurencia obtusa, Amphiroa rigida and Caulerpa chemnitzia. Massive corals with higher algal records were S. siderea (9 species), M. cavernosa (19 species) and P. strigosa (17 species). The algal assemblages on the massive corals presented low similarity. However, no significant dissimilar groups were detected. Only S. siderea and M. cavernosa are relatively similar in phycological composition. The results suggest that the massive corals of the Oro Verde reef are vulnerable to the colonization of algae, but it is necessary to investigate the conditions preceding algal settlement.

scholarly journals Coverage Increases of Porites astreoides in Grenada Determined by Shifts in Size-Frequency Distribution

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 288
Author(s):  
Ryan G. Eagleson ◽  
John S. Lumsden ◽  
Lorenzo Álvarez-Filip ◽  
Christophe M. Herbinger ◽  
Ryan A. Horricks
Keyword(s):  
Coral Community ◽  
Scleractinian Corals ◽  
Area Measurement ◽  
Coralline Algae ◽  
Measurement Tool ◽  
Size Frequency Distribution ◽  
Point Count ◽  
Porites Astreoides ◽  
The Mean ◽  
The Caribbean

Despite coral community collapse, the mustard hill coral (Porites astreoides) is a species currently experiencing success throughout the Caribbean. The inshore reefs of Grenada were selected to study the influence of benthic factors on the abundance, size, and coverage of P. astreoides colonies. Surveys of reef communities along established 30 m transects were conducted at eight sites in 2014 and 2017 using a 0.5 m² quadrat. Coral Point Count was used to annotate the images, estimating the coverage of scleractinian corals, sponges, algae, and benthic substrates. Coverage, size, and abundance of P. astreoides colonies were quantified using the area measurement tool in ImageJ standardized against the quadrats. There were significant differences in benthic community assemblages between islands, selected sites, and between years. From 2014 to 2017 there was a significant decrease in the mean abundance of P. astreoides colonies and significant increases in mean colony size and coverage. The presence of P. astreoides colonies was significantly correlated with: rubble (−), sand (−); pavement (+); macroalgae (−); coralline algae (+); sponges (varying response); gorgonians (−); massive corals (+); and branching corals (−). P. astreoides follows similar recruitment patterns as other scleractinian corals. Observed changes in P. astreoides populations appear to indicate a recovery event following a disturbance, potentially tropical storm Chantal in 2013.

Pools of resilience

2021 ◽  
Author(s):  
David Abrego ◽  
Andrew H Baird ◽  
Emily Howells ◽  
Stephen DA Smith
Keyword(s):  
Climate Change ◽  
Climate Change Adaptation ◽  
Coral Species ◽  
Scleractinian Corals ◽  
Rock Pools ◽  
Southeastern Australia ◽  
Extreme Habitat

We describe an extreme habitat for scleractinian corals in intertidal rock pools of southeastern Australia. The pools host a small but hardy subset of coral species despite experiencing conditions beyond those documented for corals anywhere in Australia. Understanding mechanisms behind this may improve insights into climate change adaptation in corals.

scholarly journals Structure of the phytoplankton community in the Cachoeira Dourada reservoir (GO/MG), Brazil

2011 ◽  
Vol 71 (3) ◽  
pp. 587-600 ◽  
Author(s):  
M. Teixeira de Oliveira ◽  
O. Rocha ◽  
AC. Peret
Keyword(s):  
Phytoplankton Community ◽  
Driving Forces ◽  
Climatic Factors ◽  
Euphotic Zone ◽  
Taxonomic Composition ◽  
Nitrogen And Phosphorus ◽  
Physical And Chemical Variables ◽  
Algal Assemblages ◽  
Physical And Chemical

The limnological features and the phytoplankton community of the Cachoeira Dourada reservoir were analyzed in December 2006, May 2007 and November 2007. Temporal changes in the taxonomic composition, density, diversity and dominance of species were analyzed in relation to climatic factors and the physical and chemical characteristics of the water. A positive correlation was found between some of the physical and chemical variables and the phytoplankton community. According to the CCA, variables such as the extent of the euphotic zone, temperature, pH, nitrogen and phosphorus concentrations directly affected the phytoplankton dynamics. Organisms belonging to the class Cyanophyceae were the most representative in all the sampling periods, comprising the functional groups K, S1, M and H. Hydrodynamics and seasonal fluctuations of environmental factors were the driving forces determining the composition and abundance of the algal assemblages. Despite the prevalence of Cyanobacteria, the reservoir is still oligotrophic. The absence of blooms and the relatively low population abundances indicated that the quality of the reservoir's water still lies within the limits required for its multiples uses.

scholarly journals Variation in susceptibility among three Caribbean coral species and their algal symbionts indicates the threatened staghorn coral, Acropora cervicornis, is particularly susceptible to elevated nutrients and heat stress

2021 ◽  
Author(s):  
Ana M. Palacio-Castro ◽  
Caroline E. Dennison ◽  
Stephanie M. Rosales ◽  
Andrew C. Baker
Keyword(s):  
Heat Stress ◽  
Coral Species ◽  
Coral Cover ◽  
Photochemical Efficiency ◽  
Acropora Cervicornis ◽  
Nutrient Inputs ◽  
Algal Symbionts ◽  
Algal Symbiont ◽  
Orbicella Faveolata ◽  
Significant Mortality

Coral cover is declining worldwide due to multiple interacting threats. We compared the effects of elevated nutrients and temperature on three Caribbean corals: Acropora cervicornis, Orbicella faveolata, and Siderastrea siderea. Colonies hosting different algal types were exposed to either ambient nutrients (A), elevated NH4 (N), or elevated NH4 + PO4 (N+P) at control temperatures (26 °C) for > 2 months, followed by a 3-week thermal challenge (31.5 °C). A. cervicornis hosted Symbiodinium (S. fitti) and was highly susceptible to the combination of elevated nutrients and temperature. During heat stress, A. cervicornis pre-exposed to elevated nutrients experienced 84%-100% mortality and photochemical efficiency (Fv/Fm) declines of 41-50%. In comparison, no mortality and lower Fv/Fm declines (11-20%) occurred in A. cervicornis that were heat-stressed but not pre-exposed to nutrients. O. faveolata and S. siderea response to heat stress was determined by their algal symbiont community and was not affected by nutrients. O. faveolata predominantly hosted Durusdinium trenchii or Breviolum, but only corals hosting Breviolum were susceptible to heat, experiencing 100% mortality, regardless of nutrient treatment. S. siderea colonies predominantly hosted Cladocopium C1 (C. goreaui), Cladocopium C3, D. trenchii, or variable proportions of Cladocopium C1 and D. trenchii. This species was resilient to elevated nutrients and temperature, with no significant mortality in any of the treatments. However, during heat stress, S. siderea hosting Cladocopium C3 suffered higher reductions in Fv/Fm (41-56%) compared to S. siderea hosting Cladocopium C1 and D. trenchii (17-26% and 10-16%, respectively). These differences in holobiont susceptibility to elevated nutrients and heat may help explain historical declines in A. cervicornis starting decades earlier than other Caribbean corals. Our results suggest that tackling only warming temperatures may be insufficient to ensure the continued persistence of Caribbean corals, especially A. cervicornis. Reducing nutrient inputs to reefs may also be necessary for these iconic coral species to survive.

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