Maerl growth, carbonate production rates and accumulation rates in the ne atlantic

2003 ◽  
Vol 13 (S1) ◽  
pp. S21-S31 ◽  
Author(s):  
Dan Bosence ◽  
John Wilson
Keyword(s):  
Accumulation Rates ◽  
Ne Atlantic ◽  
Production Rates ◽  
Carbonate Production

scholarly journals Community structure and carbonate production of a temperate rhodolith bank from Arvoredo Island, southern Brazil

2004 ◽  
Vol 52 (3-4) ◽  
pp. 207-224 ◽  
Author(s):  
Douglas F. M. Gherardi
Keyword(s):  
Community Structure ◽  
Coralline Algae ◽  
Carbonate Content ◽  
Production Rates ◽  
Percentage Cover ◽  
Coralline Red Algae ◽  
Carbonate Production ◽  
Random Dispersal ◽  
Long Run ◽  
Main Bank

A small (100,000 m²) rhodolith bank located at the Arvoredo Marine Biological Reserve (Santa Catarina, Brazil) has been surveyed to determine the main bank components, the community structure, and carbonate production rates. Data from five photographic transects perpendicular to Arvoredo Island shore were complemented with sediment samples and shallow cores, all collected by scuba diving. The main bank component is the unattached, nongeniculate, coralline red algae Lithophyllum sp., used as substrate by the zoanthid Zoanthus sp. Percentage cover of living and dead coralline algae, zoanthids and sediment patches account for nearly 98% of the investigated area. Classification and ordination of samples showed that differences in the proportion of live and dead thalli of Lithophyllum sp. determine the relative abundances of zoanthids. Results also indicate that similarity of samples is high and community gradients are subtle. Significant differences in percentage cover along transects are concentrated in the central portion of the bank. Low carbonate content of sediments from deeper samples suggests low rates of recruitment and dispersal of coralline algae via fragmentation. However, carbonate production of Lithophyllum sp ranging from 55-136.3 g m-2 yr-1 agrees with production rates reported for other temperate settings. In the long run, rhodolith density at Arvoredo Is. is likely to be dependent upon random dispersal of spores and/or fragments from other source areas.

Patterns and Processes of Ancient Reef Crises

2011 ◽  
Vol 17 ◽  
pp. 1-14 ◽  
Author(s):  
Wolfgang Kiessling
Keyword(s):  
Mass Extinctions ◽  
Production Rates ◽  
Short Term ◽  
Carbonate Production ◽  
Meteorite Impacts ◽  
Comprehensive Database ◽  
Extinction Rates ◽  
High Volatility ◽  
Patterns And Processes ◽  
Geologic Record

Reef crises need to be separated from mass extinctions because they are manifested in reductions of reefal carbonate production rather than elevated extinction rates. The volume of preserved fossil reefs per unit time is perhaps the best accessible metric to assess reefal carbonate production rates in the geologic record. Although this metric is prone to biases introduced by weathering, burial, and sampling, it offers the possibility to analyze general connections between reef crises and mass extinctions. The biases can be partially corrected by looking at short-term variations and by utilizing independent proxies of sampling. Using a comprehensive database of ancient reefs and considering the generally high volatility in reefal carbonate production, we can identify five significant metazoan reef crises in the post-Cambrian Phanerozoic, only three of which correspond to traditional mass extinctions. Ancient reefs crises appear to be due to episodes of rapid CO2release and warming, rather than cooling or meteorite impacts.

Cenomanian–Turonian drowning of the Arabian Carbonate Platform, the İnişdere section, Adıyaman, SE Turkey

2019 ◽  
Vol 498 (1) ◽  
pp. 189-210 ◽  
Author(s):  
O. Mulayim ◽  
O. I. Yilmaz ◽  
B. Sarı ◽  
K. Tasli ◽  
M. Wagreich
Keyword(s):  
Sea Level ◽  
Carbonate Platform ◽  
Accumulation Rates ◽  
Sea Level Changes ◽  
Carbonate Production ◽  
Oceanic Anoxic Event ◽  
Anoxic Event ◽  
Anoxic Events ◽  
Se Turkey ◽  
Arabian Platform

AbstractThe Cenomanian–Turonian carbonate ramp in the Adıyaman Region of SE Turkey (Northern Arabian Platform) records an abrupt shift from benthic carbonate deposits to pelagic deposits near the Cenomanian–Turonian boundary event (CTBE) in the İnişdere stratigraphic section and surrounding borehole sections. A positive δ13C excursion of up to 2.15% is recorded in carbonate and organic carbon deposited around the CTBE and provides evidence of a direct link between the CTBE and oceanic anoxic events and the demise of the shallow carbonate production in the Derdere Formation. The microfacies analyses, biostratigraphic dating and palaeoenvironmental interpretations suggest that the platform was drowned near the CTBE as a result of changing environmental conditions. The microfacies indicating significant deepening show a contemporaneity to equivalent surfaces globally and thus strongly support an isochronous formation of Cenomanian–Turonian facies by eustatic sea-level changes. Anoxia spreading over the platform drastically reduced the carbonate production as observed in the studied sections and, therefore, resulted in a reduction in carbonate accumulation rates. Regional/local subsidence and a coeval sea-level rise during the late Cenomanian to early Turonian interval were the cause of the drowning of the platform, including regional anoxia at the northern Arabian platform linked to the Cenomanian–Turonian oceanic anoxic event (OAE2).

Determinants of Mollusk Abundance in Quaternary cores of Po Basin, Italy

2020 ◽  
Author(s):  
Michał Kowalewski ◽  
Rafał Nawrot ◽  
Daniele Scarponi ◽  
Michele Azzarone
Keyword(s):  
Fossil Record ◽  
Late Quaternary ◽  
Abundant Species ◽  
Growth Patterns ◽  
Trophic Levels ◽  
Accumulation Rates ◽  
Production Rates ◽  
Extrinsic Factors ◽  
Sequence Stratigraphic ◽  
Shell Production

<p>Absolute abundance of fossils observed in cores and outcrops can be governed by extrinsic processes (e.g., net accumulation rates, intensity of taphonomic processes, post-mortem transport), intrinsic determinants of shell production rates (e.g., fecundity, spawning frequency, growth patterns), or some combination of those interdependent factors. Understanding the role of drivers of fossil abundance can enhance stratigraphic and biological interpretations of the fossil record. To assess the importance of extrinsic and intrinsic processes for fossil mollusks, we used a total of over 400 samples (each representing a 10-cm core interval and ∼0.375 dm<sup>3</sup> of sediment) derived from 12 cores from the late Quaternary sedimentary succession of the Po basin (Italy). The results indicate that although extrinsic factors such as compaction, net accumulation rates, and sequence stratigraphic context are to some degree controlling mollusk abundance in the cores, they cannot account for extremely shell-rich deposits. The results suggest instead that shell-rich core intervals record, primarily, episodes of high shell production rates. First, samples with very high shell density (> 4000 specimens per dm3) were characterized by extremely low evenness reflecting dominance by one super-abundant species, typically a small r-selective species capable of an explosive population growth (<em>Lentidium mediterraneum</em> and <em>Ecrobia ventrosa</em>). Second, a taphonomic test supported further the biological (R-hardparts model) rather than sedimentological (R-sediment model) origin of very dense shell concentrations: the quality of shell preservation correlates positively with shell density as predicted by R-hardparts model. The results suggest that intervals of high abundance of mollusk shells in cores record intervals of high biological productivity driven by opportunistic shelly species from lower trophic levels. Integrative studies of facies architecture, sequence stratigraphy, and paleontological data can help to differentiate biologically and physically produced fossil concentrations thus allowing for more informed ecological interpretations of the fossil record.</p>

The infection characteristics of the antelope schistosomes, Schistosoma margrebowiei and S. leiperi, in inbred BALB/c mice and in Mastomys coucha

1994 ◽  
Vol 68 (1) ◽  
pp. 19-33
Author(s):  
C.D. Dettman ◽  
S.B. Higgins-Opitz
Keyword(s):  
Sexual Maturity ◽  
Egg Production ◽  
Egg Laying ◽  
Accumulation Rates ◽  
Production Rates ◽  
Daily Output ◽  
Egg Deposition ◽  
Mastomys Coucha

AbstractDetailed studies were carried out to assess the infection characteristics of the antelope schistosomes in BALB/c mice and Mastomys coucha. Both schistosome species reached sexual maturity in these hosts. However, they differed markedly in terms of egg production rates and preferred sites of tissue egg deposition. Tissue egg deposition commenced between 4 and 5 weeks in the case of Schistosoma margrebowiei and between 6 and 7 weeks in the case of S. leiperi. Tissue egg accumulation rates of S. leiperi were calculated to be 334 and 311 eggs/gravid worm pair/day in mice and M. coucha, respectively. The fecundity of S. margrebowiei was found to be substantially greater (approximately 5 times; daily output ranging from 1600–1900 eggs/gravid worm pair). While S. leiperi infections remained relatively stable in both hosts during the study period (i.e. up to 15 weeks after onset of egg laying), S. margrebowiei infections were observed to deteriorate rapidly in M. coucha.

VARIATION OF CORTISOL METABOLISM AS A CONTRIBUTING FACTOR TO DISCREPANCIES IN THE MEASUREMENT OF CORTISOL PRODUCTION RATE

1972 ◽  
Vol 70 (1) ◽  
pp. 89-96 ◽  
Author(s):  
M. J. Levell
Keyword(s):  
Production Rate ◽  
Isotope Dilution ◽  
Normal Subjects ◽  
Contributory Factor ◽  
Morning Dose ◽  
Production Rates ◽  
Evening Dose ◽  
Cortisol Metabolism

ABSTRACT Five normal subjects were given [14C] cortisol in the morning and [3H] cortisol in the evening, in both cases by mouth. The excretion of radioactivity in tetrahydrocortisol (THF) and tetrahydrocortisone (THE) was measured by a modified form of reverse isotope dilution. In 2 subjects, the ratio of isotopic THF/isotopic THE was higher after the evening dose than after the morning dose. In 1 subject the ratio decreased. In 2 subjects it did not change. Cortisol production rates calculated from THF were usually higher than those calculated from THE. The observed variations of metabolism were only a contributory factor to these discrepancies.

Sign in / Sign up

Export Citation Format

Share Document