Bird attributes, plant characteristics, and seed dispersal of Pera glabrata (Schott, 1858), (Euphorbiaceae) in a disturbed cerrado area

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

ESTIVATION IN SOUTH-AMERICAN AMPHIBIANS AND REPTILES

A number of amphibians and reptiles have cyclic behavior, becoming inactive with the coming of the dry season. In South America this pattern of activity is common, particularly in savannah-like vegetation. During the dry season amphibians burrow into the mud or soil, and either form a cocoon or increase the osmotic concentration of body fluids to reduce evaporative water loss. Some phyllomedusid tree frogs coat their body surface with skin secretion and excrete uric acid to minimize water loss. Reptiles also retreat into shelter deep enough to avoid temperature fluctuation during estivation or reduce metabolic response to temperature. Reduction of temperature sensitivity of the metabolism seems to be a strategy common to estivating amphibians and reptiles. Despite seasonal change of the environment, some species of reptiles are active all year round.

Sedimentation rates of tripton in Jurumirim Reservoir (São Paulo, Brazil)

Sedimentation rates of particulate material and some physicochemical parameters of water were determined in October, January, April and July 1990-91 at seven stations in the Jurumirim Reservoir (São Paulo, Brazil), three located in the Paranapanema arm, three in the Taquari arm and one near the dam. Higher sedimentation rates of tripton were found in the Paranapanema arm, followed by those from the Taquari arm and the dam. Suspended matter (2.5-48.7 mg · 1-1) and chlorophyll-a (0.7-8.1 mg · m-3) concentrations in the Paranapanema arm were in general higher resulting in lower water transparency (0.3-1.7m) than in the Taquari arm. Temporal and spatial variations in the tripton sedimentation rates were mainly influenced by allochthonous input at the stations near the river mouth. The settling fluxes at station near the dam of the reservoir were affected rather by a small autochthonous production (65 g C ass m-2 ;yr-1), indicated by a higher organic content (64-87%). Therefore, sedimentation rates measured by bottom traps were affected by sediment ressuspension especially at isothermal conditions. With respect to sedimentation, the riverine, the transition and the lacustrine zones commonly found in reservoires could be distinguished. The extent of the riverine zone in each arm of the Jurumirim Reservoir depends on the seasonal change of allochthonous input.

Effects of Atmospheric Nitrogen Deposition on the Herbaceous Layer of a Central Appalachian Hardwood Forest

Additions of nitrogen (N) have been shown to alter species diversity of plant communities, with most experimental studies having been carried out in communities dominated by herbaceous species. We examined seasonal and inter-annual patterns of change in the herbaceous layer of two watersheds of a central Appalachian hardwood forest that differed in experimental treatment. This study was carried out at the Fernow Experimental Forest, West Virginia, using two adjacent watersheds: WS4 (mature, second-growth hardwood stand, untreated reference), and WS3. Seven circular 0.04-ha sample plots were established in eachwatershed to represent its full range of elevation and slope aspect. The herbaceous layer was sampled by identifying and visually estimating cover (%) of all vascular plants. Sampling was carried out in mid-July of 1991 and repeated at approximately the same time in 1992. In 1994, these same plots were sampled each month fromMay to October. Seasonal patterns of herb layer dynamics were assessed for the complete 1994 data set, whereasinter-annual variability was based on plot data from 1991, 1992, and the July sample of 1994. There were nosignificant differences between watersheds for any sample year for any of the other herb layer characteristics measured, including herb layer cover, species richness, evenness, and diversity. Cover on WS4 decreased significantly from 1991 to 1992, followed by no change to 1994. By contrast, herb layer cover did not varysignificantly across years on WS3. Cover of the herbaceous layer of both watersheds increased from early in the growing season to the middle of the growing season, decreasing thereafter, with no significant differencesbetween WS3 and WS4 for any of the monthly cover means in 1994. Similar seasonal patterns found for herblayer cover—and lack of significant differences between watersheds—were also evident for species diversityand richness. By contrast, there was little seasonal change in herb layer species evenness, which was nearlyidentical between watersheds for all months except October. Seasonal patterns for individual species/speciesgroups were closely similar between watersheds, especially for Viola rotundifolia and Viola spp. Species richnessand species diversity were linearly related to herb layer cover for both WS3 and WS4, suggesting that spatialand temporal increases in cover were more related to recruitment of herb layer species than to growth of existingspecies. Results of this study indicate that there have been negligible responses of the herb layer to 6 yr of additions to WS3.

(Table 2) Integrated concentration, production and dissolution of silica in the water column of the southern Pacific

An intense diatom bloom developed within a strong meridional silicic acid gradient across the Antarctic Polar Front at 61°S, 170°W following stratification of the water column in late October/early November 1997. The region of high diatom biomass and the silicic acid gradient propogated southward across the Seasonal Ice Zone through time, with the maximum diatom biomass tracking the center of the silicic acid gradient. High diatom biomass and high rates of silica production persisted within the silicic acid gradient until the end of January 1998 (ca. 70 d) driving the gradient over 500 km to the south of its original position at the Polar Front. The bloom consumed 30 to >40 µM Si(OH)4 in the euphotic zone between about 60 and 66°S leaving near surface concentrations <2.5 µM and occasionally <1.0 µM in its wake. Integrated biogenic silica concentrations within the bloom averaged 410 mmol Si/m**2 (range 162-793 mmol Si/m**2). Average integrated silica production on two consecutive cruises in December 1997 and January 1998 that sampled the bloom while it was well developed were 27.5±6.9 and 22.6±20 mmol Si/m**2/d, respectively. Those levels of siliceous biomass and silica production are similar in magnitude to those reported for ice-edge diatom blooms in the Ross Sea, Antarctica, which is considered to be among the most productive regions in the Southern Ocean. Net silica production (production minus dissolution) in surface waters during the bloom was 16-21 mmol Si/m**2/d, which is sufficient for diatom growth to be the cause of the southward displacement of the silicic acid gradient. A strong seasonal change in silica dissolution : silica production rate ratios was observed. Integrated silica dissolution rates in the upper 100-150 m during the low biomass period before stratification averaged 64% of integrated production. During the bloom integrated dissolution rates averaged only 23% of integrated silica production, making 77% of the opal produced available for export to depth. The bloom ended in late January apparently due to a mixing event. Dissolution : production rate ratios increased to an average of 0.67 during that period indicating a return to a predominantly regenerative system. Our observations indicate that high diatom biomass and high silica production rates previously observed in the marginal seas around Antarctica also occur in the deep ocean near the Polar Front. The bloom we observed propagated across the latitudinal band overlying the sedimentary opal belt which encircles most of Antarctica implying a role for such blooms in the formation of those sediments. Comparison of our surface silica production rates with new estimates of opal accumulation rates in the abyssal sediments of the Southern Ocean, which have been corrected for sediment focusing, indicate a burial efficiency of <=4.6% for biogenic silica. That efficiency is considerably lower than previous estimates for the Southern Ocean.

Light adsorption of phytoplankton and parameters of its biomass and cell biovolumes in the Black Sea in 1998-2000

Bio-optical characteristics of phytoplankton have been observed during two-year monitoring in the western Black Sea. High variability in light absorption coefficient of phytoplankton was due to change of pigment concentration and chlorophyll a specific absorption coefficient. A relationships between light absorption coefficients and chlorophyll a concentration have been found: for the blue maximum (a_ph(440) = 0.0413x**0.628; R**2 = 0.63) and for the red maximum (?_ph(678) = 0.0190x**0.843; R**2 = 0.83). Chlorophyll a specific absorption coefficients decreased while pigment concentration in the Sea increased. Observed variability in chlorophyll a specific absorption coefficient at chlorophyll a concentrations <1.0 mg/m**3 had seasonal features and was related with seasonal change of intracellular pigment concentration. Ratio between the blue and red maxima decreased with increasing chlorophyll a concentration (? = 2.14 x**-0.20; R**2 = 0.41). Variability of spectrally averaged absorption coefficient of phytoplankton (a'_ph ) on 95% depended on absorption coefficient at the blue maximum (y = 0.421x; R**2 = 0.95). Relation of a_ph with chlorophyll a concentration was described by a power function (y = 0.0173x**0.0709; R**2 = 0.65). Change of spectra shape was generally effected by seasonal dynamics of intracellular pigment concentration, and partly effected by taxonomic and cell-size structure of phytoplankton.

Iron in the Sargasso Sea

We report iron measurements for water column and aerosol samples collected in the Sargasso Sea during July-August 2003 (summer 2003) and April-May 2004 (spring 2004). Our data reveal a large seasonal change in the dissolved iron (dFe) concentration of surface waters in the Bermuda Atlantic Time-series Study region, from ~1-2 nM in summer 2003, when aerosol iron concentrations were high (mean 10 nmol/m**3), to ~0.1-0.2 nM in spring 2004, when aerosol iron concentrations were low (mean 0.64 nmol/m**3). During summer 2003, we observed an increase of ~0.6 nM in surface water dFe concentrations over 13 days, presumably due to eolian iron input; an estimate of total iron deposition over this same period suggests an effective solubility of 3-30% for aerosol iron. Our summer 2003 water column profiles show potentially growth-limiting dFe concentrations (0.02-0.19 nM) coinciding with a deep chlorophyll maximum at 100-150 m depth, where phytoplankton biomass is typically dominated by Prochlorococcus during late summer.

Seawater carbonate chemistry and biological processes during experiments with temperate coral Cladocora caespitosa, 2010

Atmospheric CO2 partial pressure (pCO2) is expected to increase to 700 µatm or more by the end of the present century. Anthropogenic CO2 is absorbed by the oceans, leading to decreases in pH and the CaCO3 saturation state of the seawater. Elevated pCO2 was shown to drastically decrease calcification rates in tropical zooxanthellate corals. Here we show, using the Mediterranean zooxanthellate coral Cladocora caespitosa, that an increase in pCO2, in the range predicted for 2100, does not reduce its calcification rate. Therefore, the conventional belief that calcification rates will be affected by ocean acidification may not be widespread in temperate corals. Seasonal change in temperature is the predominant factor controlling photosynthesis, respiration, calcification and symbiont density. An increase in pCO2, alone or in combination with elevated temperature, had no significant effect on photosynthesis, photosynthetic efficiency and calcification. The lack of sensitivity C. caespitosa to elevated pCO2 might be due to its slow growth rates, which seem to be more dependent on temperature than on the saturation state of calcium carbonate in the range projected for the end of the century.

Distribution of calcareous nannofossils in the Miocene interval of DSDP Hole 94-608 in the north Atlantic (Fig. 1)

DSDP North Atlantic Site 608 yielded an excellent Miocene pelagic section which affords a further opportunity for elucidating the chronology of the calcareous nannofossil succession in the framework of magnetostratigraphic control. Most of the conventional (zonal) markers have been documented for this site and some of the earlier results are confirmed and refined. In addition several unconventional and less known markers have been added. The first two are the highest (last) occurrence of Sphenolithus delphix and Sphenolithus capricornutus at 23.6 Ma, which is immediately above the Oligocene-Miocene boundary as identified by the last occurrence of Reticulofenestra bisecta at 23.7 Ma. The next unconventional datum is the highest (last) occurrence of Ilselithina fusa at 22.8 Ma, which is also the highest (last) occurrence of Helicosphaera recta. Calcidiscus tropicus' lowest (first) occurrence is at 19.5 Ma, which is also the lowest occurrence of Sphenolithus belemnos, and Calcidiscus leptoporus' lowest (first) occurrence coincides with that of Sphenolithus heteromorphus at 18.5 Ma. Sphenolithus dissimilis' highest (last) occurrence is at 18.2 Ma and the Calcidiscus premacintyrei lowest (first) and highest (last) occurrences are, respectively, at 17.7 and 11.7 Ma. Discoaster braarudii occurs from 11.6 to 11.3 Ma and its highest (last) occurrence corresponds to that of Cyclicargolithus floridanus. Minylitha convallis occurs from 9.0 to 6.9 Ma. Within the range of Minylitha, at 8.0 Ma, a major shift occurs in reticulofenestrid placoliths from dominantly large (Reticulofenestra pseudoumbilicus) and medium size (Reticulofenestra minutula) species below to significant numbers of very small species (Dictyococcites productus and Gephyrocapsa) above. This is interpreted to be a major, though perhaps seasonal, change of productivity of the North Atlantic at Site 608. A new genus and species Cryptococcolithus takayamae, is described and a variety, Reticulofenestra pseudoumbilicus var. amplus is identified.

Beach changes at Holden Beach, North Carolina, 1970-74 /

Beach profile lines at 21 near-evenly spaced intervals along Holden Beach, North Carolina, between Lockwoods Folly and Shallotte Inlets, were measured from November 1970 to December 1974. These have been analyzed to determine the spatial and temporal variabilities on long-term, seasonal, and short-term scales. Profile lines near the inlets showed the greatest variability in mean sea level (MSL) position, above MSL volume, foreshore slope, and profile envelope. This variability near Lockwoods Folly Inlet was partly enhanced by artificial nourishment at profile line 2. Temporary, low-cost shore protection devices (e.g., sandbag groins) were constructed near that inlet during part of the study. No other modifications or activities that affected beach processes were known to occur during the study period. The central part of Holden Beach was studied separately because of the high variability of the inlet sections at either end of the island. Foreshore slopes along this reach increased from an average of 1:30 at the east end to 1:17 at the west. A seasonal change in above MSL volume indicates loss of sand during autumn and winter, and gain during spring and summer. Changes in MSL shoreline intercept and above MSL volume were highly variable during the study.

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Shell flux and oxygen isotope data of North Atlantic foraminifera

We present an almost 3 year long time series of shell fluxes and oxygen isotopes of left-coiling Neogloboquadrina pachyderma and Turborotalita quinqueloba from sediment traps moored in the deep central Irminger Sea. We determined their response to the seasonal change from a deeply mixed water column with occasional deep convection in winter to a thermally stratified water column with a surface mixed layer (SML) of around 50 m in summer. Both species display very low fluxes during winter with a remnant summer population holding out until replaced by a vital population that seeds the subsequent blooms. This annual population overturning is marked by a 0.7 per mill increase in d18O in both species. The shell flux of N. pachyderma peaks during the spring bloom and in late summer, when stratification is close to its minimum and maximum, respectively. Both export periods contribute about equally and account for >95% of the total annual flux. Shell fluxes of T. quinqueloba show only a single broad pulse in summer, thus following the seasonal stratification cycle. The d18O of N. pachyderma reflects temperatures just below the base of the seasonal SML without offset from isotopic equilibrium. The d18O pattern of T. quinqueloba shows a nearly identical amplitude and correlates highly with the d18O of N. pachyderma. Therefore T. quinqueloba also reflects temperature near the base of the SML but with a positive offset from isotopic equilibrium. These offsets contrast with observations elsewhere and suggest a variable offset from equilibrium calcification for both species. In the Irminger Sea the species consistently show a contrast in their flux timings. Their flux-weighted delta d18O will thus dominantly be determined by seasonal temperature differences at the base of the SML rather than by differences in their depth habitat. Consequently, their sedimentary delta d18O may be used to infer the seasonal contrast in temperature at the base of the SML.

Seawater carbonate chemistry, calcification and photosynthesis during experiments with corals, 2005

An investigation was conducted to determine the effects of elevated pCO2 on the net production and calcification of an assemblage of corals maintained under near-natural conditions of temperature, light, nutrient, and flow. Experiments were performed in summer and winter to explore possible interactions between seasonal change in temperature and irradiance and the effect of elevated pCO2. Particular attention was paid to interactions between net production and calcification because these two processes are thought to compete for the same internal supply of dissolved inorganic carbon (DIC). A nutrient enrichment experiment was performed because it has been shown to induce a competitive interaction between photosynthesis and calcification that may serve as an analog to the effect of elevated pCO2. Net carbon production, NPC, increased with increased pCO2 at the rate of 3 ± 2% (?mol CO2aq kg?1)?1. Seasonal change of the slope NPC-[CO2aq] relationship was not significant. Calcification (G) was strongly related to the aragonite saturation state ? a . Seasonal change of the G-? a relationship was not significant. The first-order saturation state model gave a good fit to the pooled summer and winter data: G = (8 ± 1 mmol CaCO3 m?2 h?1)(? a ? 1), r 2 = 0.87, P = 0.0001. Both nutrient and CO2 enrichment resulted in an increase in NPC and a decrease in G, giving support to the hypothesis that the cellular mechanism underlying the decrease in calcification in response to increased pCO2 could be competition between photosynthesis and calcification for a limited supply of DIC.