Coral disease dynamics and environmental drivers in the northern Florida Keys and Lee Stocking Island, Bahamas

Coral reefs are experiencing declines worldwide and recently coral diseases have been identified as significant contributors to coral mortality. However, little is known regarding the factors that drive coral disease distributions and dynamics. Current knowledge of the organisms that cause coral diseases is also limited, with pathogens having been identified for only 5 of the 21 described coral diseases. The study presented here describes coral disease dynamics in terms of occurrence, prevalence, spatial distribution, and host species susceptibility from 2002--2004 on reefs of the Northern Florida Keys (NFK) and Lee Stocking Island (LSI) in the Bahamas' Exuma chain. In addition, this research investigated the influence of temperature, sediment, and nutrient availability on coral disease prevalence and severity. Finally, microbial communities associated with a polymicrobial disease, black band, were examined to address spatial and temporal variability. ^ Four scleractinian diseases were observed in repeated surveys conducted during June-August of each year: black band disease (BBD), white plague type 2 (WP), dark spots syndrome (DSS), and yellow band disease-(YBD). Coral disease prevalence was generally low in both the NFK and LSI as compared to epizootic levels reported previously in the NFK and other regions of the Caribbean. Disease prevalence and species susceptibility varied spatially and temporally. Massive framework species, including Siderastrea siderea, Colpophyllia natans, and Montastraea annularis, along with relatively smaller colonies of Meandrina meandrites and Dichocoenia stokesi, were most susceptible to disease. Temperature, sedimentation, and dissolved inorganic nitrogen were positively correlated with BBD infections. Furthermore, experimental nutrient enrichment exacerbated coral tissue loss to BBD both in situ and in vivo. Profiling of BBD microbial communities using length heterogeneity PCR revealed variation over space and time, with significantly distinct bacterial assemblages in the NFK, LSI, and US Virgin Islands. ^ This study contributes to knowledge of the relationship between coral diseases and the environment, and facilitates predictions regarding potential changes in coral reef communities under differing environmental conditions. Additionally, this research provides further understanding of coral disease dynamics at both the host and microbial pathogen levels.^

Pollen and dinoflagellate cyst counts on sediment core M72/5_628-1 (MD72/5-25-GC1) from the Black Sea

High-resolution pollen and dinoflagellate cyst records from sediment core M72/5-25-GC1 were used to reconstruct vegetation dynamics in northern Anatolia and surface conditions of the Black Sea between 64 and 20 ka BP. During this period, the dominance of Artemisia in the pollen record indicates a steppe landscape and arid climate conditions. However, the concomitant presence of temperate arboreal pollen suggests the existence of glacial refugia in northern Anatolia. Long-term glacial vegetation dynamics reveal two major arid phases ~64-55 and 40-32 ka BP, and two major humid phases ~54-45 and 28-20 ka BP, correlating with higher and lower summer insolation, respectively. Dansgaard-Oeschger (D-O) cycles are clearly indicated by the 25-GC1 pollen record. Greenland interstadials are characterized by a marked increase in temperate tree pollen, indicating a spread of forests due to warm/wet conditions in northern Anatolia, whereas Greenland stadials reveal cold and arid conditions as indicated by spread of xerophytic biomes. There is evidence for a phase lag of ~500 to 1500 yr between initial warming and forest expansion, possibly due to successive changes in atmospheric circulation in the North Atlantic sector. The dominance of Pyxidinopsis psilata and Spiniferites cruciformis in the dinocyst record indicates brackish Black Sea conditions during the entire glacial period. The decrease of marine indicators (marine dinocysts, acritarchs) at ~54 ka BP and increase of freshwater algae (Pediastrum, Botryococcus) from 32 to 25 ka BP reveals freshening of the Black Sea surface water. This freshening is possibly related to humid phases in the region, to connection between Caspian Sea and Black Sea, to seasonal freshening by floating ice, and/or to closer position of river mouths due to low sea level. In the southern Black Sea, Greenland interstadials are clearly indicated by high dinocyst concentrations and calcium carbonate content, as a result of an increase in primary productivity. Heinrich events show a similar impact on the environment in the northern Anatolia/Black Sea region as Greenland stadials.

(Table 1) Abundance of unicellular eukaryotes in ice cores collected during the July 2008 CCGS Amundsen cruise in Darnley Bay

Influence of methanogenic populations in Holocene lacustrine sediments revealed by clone libraries and fatty acid biogeochemistry.Biological characteristics of ice-associated algal communities were studied in Darnley Bay (western Canadian Arctic) during a 2-week period in July 2008 when the landfast ice cover had reached an advanced stage of melt. We found two distinct and separate algal communities: (1) an interior ice community confined to brine channel networks beneath white ice covers; and (2) an ice melt water community in the brackish waters of both surface melt ponds and the layer immediately below the ice cover. Both communities reached maximum chlorophyll a concentrations of about 2.5 mg/m**3, but with diatoms dominating the interior ice while flagellates dominated the melt water community. The microflora of each community was diverse, containing both unique and shared algal species, the latter suggesting an initial seeding of the ice melt water by the bottom ice community. Absorption characteristics of the algae indicated the presence of mycosporine-like amino acids (MAAs) and carotenoid pigments as a photoprotective strategy against being confined to high-light near-surface layers. Although likely not contributing substantially to total annual primary production, these ice-associated communities may play an important ecological role in the Arctic marine ecosystem, supplying an accessible and stable food source to higher trophic levels during the period of ice melt.

R-codes, and coral abundance, water temperature and transect characteristics of nearshore reefs in Belize

Coral reefs are increasingly threatened by global and local anthropogenic stressors, such as rising seawater temperature and nutrient enrichment. These two stressors vary widely across the reef face and parsing out their influence on coral communities at reef system scales has been particularly challenging. Here, we investigate the influence of temperature and nutrients on coral community traits and life history strategies on lagoonal reefs across the Belize Mesoamerican Barrier Reef System (MBRS). A novel metric was developed using ultra-high-resolution sea surface temperatures (SST) to classify reefs as enduring low (lowTP), moderate (modTP), or extreme (extTP) temperature parameters over 10 years (2003 to 2012). Chlorophyll-a (chl a) records obtained for the same interval were employed as a proxy for bulk nutrients and these records were complemented with in situ measurements to "sea truth" nutrient content across the three reef types. Chl a concentrations were highest at extTP sites, medial at modTP sites and lowest at lowTP sites. Coral species richness, abundance, diversity, density, and percent cover were lower at extTP sites compared to lowTP and modTP sites, but these reef community traits did not differ between lowTP and modTP sites. Coral life history strategy analyses showed that extTP sites were dominated by hardy stress-tolerant and fast-growing weedy coral species, while lowTP and modTP sites consisted of competitive, generalist, weedy, and stress-tolerant coral species. These results suggest that differences in coral community traits and life history strategies between extTP and lowTP/modTP sites were driven primarily by temperature differences with differences in nutrients across site types playing a lesser role. Dominance of weedy and stress-tolerant genera at extTP sites suggests that corals utilizing these two life history strategies may be better suited to cope with warmer oceans and thus may warrant further protective status during this climate change interval. Data associated with this project are archived here, including: -SST data -Satellite Chl a data -Nutrient measurements -Raw coral community survey data For questions contact Justin Baumann (j.baumann3 gmail.com)

Pollen record from Eifel maar

A new interglacial pollen sequence from the Döttinger dry maar in the Eifel region of the Rheinish Schield is presented. Palynology is used to correlated to several classical north German Holsteinian sites. The lake sediments reveal the complete interglacial and also 60 m of laminated sediments from the glacial preceding the Holsteinian. The interglacial section indicates limnic conditions in its lower part and telmatic conditions in its upper part with an intermediate episode of peat formation. Ash layers document internsive volcansim during the interglacial in the Eifel region. Some of the north German Holsteinian sites reval spikes of high abundance of Pinus, Beutal and Poaceae and/or setbacks of more demanding taxa during the interglacial, often interpreted as cold events. The Döttingen profile shows similar pattern, but with little response from the thermophilous pollen taxa. In the Döttingen sequence these vegetation 'anomalies' are preceded, or accompanied by phases of active volcanism. The role/interaction of climate and/or volcanism as a likely cause for these vegetation 'anomalies' ist still to be quantified.

Pollen profile Tegeler See, Brandenburg, Germany

The region D-s (Fig. 15.8) belongs to the Weichselian glaciated area of the North German lowlands and is a section of the older part of the young moraine landscape. The Warsaw-Berlin Urstromtal with the Spree River and the Havel lake-river system subdivide the region into four subregions, including a northern, southern and western ground moraine plateau. The region as a whole comprises the former West-Berlin, surrounded by the late GDR.