Effect of Hydrologic Restoration on the Habitat of The Cape Sable Seaside Sparrow, Annual Report of 2004-2005

The major activities in Year 3 on ‘Effect of hydrologic restoration on the habitat of the Cape Sable seaside sparrow (CSSS)’ included presentations, field work, data analysis, and report preparation. During this period, we made 4 presentations, two at the CSSS – fire planning workshops at Everglades National Park (ENP), one at the Society of Wetland Scientists’ meeting in Charleston, SC, and a fourth at the Marl Prairie/CSSS performance measure workshop at ENP. We started field work in the third week of January and continued till June 3, 2005. Early in the field season, we completed vegetation surveys along two transects, B and C (~15.1 km). During April and May, vegetation sampling was completed at 199 census sites, bringing to 608 the total number of CSSS census sites with quantitative vegetation data. We updated data sets from all three years, 2003-05, and analyzed them using cluster analysis and ordination as in previous two years. However, instead of weighted averaging, we used weighted-averaging partial least square regression (WA-PLS) model, as this method is considered an improvement over WA for inferring values of environmental variables from biological species composition. We also validated the predictive power of the WA-PLS regression model by applying it to a sub-set of 100 census sites for which hydroperiods were “known” from two sources, i.e., from elevations calculated from concurrent water depth measurements onsite and at nearby water level recorders, and from USGS digital elevation data. Additionally, we collected biomass samples at 88 census sites, and determined live and dead aboveground plant biomass. Using vegetation structure and biomass data from those sites, we developed a regression model that we used to predict aboveground biomass at all transects and census sites. Finally, biomass data was analyzed in relation to hydroperiod and fire frequency.

Diversity Patterns of Amphibians in Lowland Amazonian Forests in Southeastern Peru

Biological diversity is threatened worldwide and it is a priority to generate more information that can be used both for understanding ecological processes and determining conservation strategies. For my dissertation, I focused on amphibian diversity patterns in lowland rainforests of southwestern Amazonia to evaluate the importance of habitat heterogeneity in the region. My main purpose was to test the hypothesis that amphibian communities in different forest types differ in species richness, composition, and abundance. I used standardized visual encounter surveys to quantify the species composition and abundance of amphibians at four sites, each containing four forest types (floodplain, terra firme, bamboo, and palm swamp). I used leaf-litter plots to evaluate the effect of soil and leaf-litter characteristics on species richness and abundance of leaf-litter frogs. I intensively sampled at one site and then sampled three other sites (distance among sites varied 3.5-105 km) to evaluate whether the patterns observed at one site were similar elsewhere. I also updated the information on threatened and potentially threatened amphibians in Peru and my study region. I found that no species appears to have experienced population declines in southeastern Peru, suggesting that the region still contains the original species pool. My results support the hypothesis that amphibian communities differ across forest types and that patterns observed at the local scale (one site) are similar at the regional scale (four sites). My data also indicate that there is no correlation between species composition and geographic distance among sites. Instead, an important proportion of the gamma diversity is represented by habitat-related beta diversity. My leaf-litter plot data showed that part of the variation in the leaf-litter community structure is explained by soil and litter characteristics. I found that soil total phosphorus and, to a lesser extent, humidity, leaf-litter mass, and pH is linked to species presence/absence and abundance. My study provides the first standardized, quantitative comparison of amphibian community structure across four major forest types in southwestern Amazonia and highlights the fact that forest types are complementary and necessary for maintaining high species richness in the region.

Coccolithophore abundance and biometry in the South China Sea, 2014

Coccolithophore contributions to the global marine carbon cycle are regulated by the calcite content of their scales (coccoliths), and the relative cellular levels of photosynthesis and calcification. All three of these factors vary between coccolithophore species, and with response to the growth environment. Here, water samples were collected in the northern basin of the South China Sea (SCS) during summer 2014 in order to examine how environmental variability influenced species composition and cellular levels of calcite content. The vertical structure of the coccolithophore community was strongly regulated by mesoscale eddies. All living coccolithophores produced within the euphotic zone (1 % of surface irradiance), and Florisphaera profunda was a substantial coccolithophore and coccolith-calcite producer in the Deep Chlorophyll-a Maximum (DCM), especially in most oligotrophic anti-cyclonic eddy centers. Placolith-bearing coccolithophores, plus F. profunda, and other larger and numerically rare species made almost equal contributions to coccolith-based calcite in the water column. For Emiliania huxleyi biometry measurements, coccolith size positively correlated with nutrients, and it is suggested that coccolith length is influenced by nutrient and light related growth rates. However, larger sized coccoliths were related to low pH and calcite saturation, although it is not a simple cause and effect relationship. Genotypic or ecophenotypic variation may also be linked to coccolith size variation.

Fresh biomass of macroalgae collected at Hansneset, Kongsfjorden, Spitsbergen in 1996/1998

We surveyed macroalgae at Hansneset, Blomstrand in Kongsfjorden, Svalbard, down to 30 m depth between 1996 and 1998. In total, 62 species were identified: 16 Chlorophyta, 25 Phaeophyceae, and 21 Rhodophyta. The majority of species (53.5%) belonged to the Arctic cold-temperate group, followed in frequency by species distributed from the Arctic to the warm-temperate region (25.9%). Four endemic Arctic species (Laminaria solidungula, Acrosiphonia flagellata, A. incurva, and Urospora elongata) were found. Two species (Pogotrichum filiforme and Mikrosyphar polysiphoniae) were new to Svalbard. Chlorophyta, Phaeophyceae, and Rhodophyta extended from the eulittoral zone down to 11, 21, and >30 m depths with maximum biomasses at 1-5 m, 5-10 m, and 5-30 m depths, respectively. Annual and pseudoperennial species had highest biomasses in the upper 5 m, while perennials were distributed deeper. The highest biomass (8600 g/m**2 wet weight) at 5 m depth comprised mainly L. digitata, Saccorhiza dermatodea, Alaria esculenta, and Saccharina latissima. The biogeographic composition of macroalgae at Hansneset was rather similar to that of northeastern Greenland, but different from that of northern Norway, which has a higher proportion of temperate species. Climate warming and ship traffic may extend some of the distribution ranges of macroalgae from mainland Norway to Svalbard.

(Table 1) Ice station data during POLARSTERN expeditions ARK-XVIII/2 and ARK-XIX/1 to Fram Strait, the western Barents Sea and north of Svalbard

During two expeditions of the R.V. "Polarstern" to the Arctic Ocean, pack ice and under-ice water samples were collected during two different seasons: late summer (September 2002) and late winter (March/April 2003). Physical and biological properties of the ice were investigated to explain seasonal differences in species composition, abundance and distribution patterns of sympagic meiofauna (in this case: heterotrophs >20 µm). In winter, the ice near the surface was characterized by extreme physical conditions (minimum ice temperature: -22°C, maximum brine salinity: 223, brine volume: <=5%) and more moderate conditions in summer (minimum ice temperature: -5.6°C, maximum brine salinity: 94, most brine volumes: >=5%). Conditions in the lowermost part of the ice did not differ to a high degree between summer and winter. Chlorophyll a concentrations (chl a) showed significant differences between summer and winter: during winter, concentrations were mostly <1.0 µg chl a/l, while chl a concentrations of up to 67.4 µmol/l were measured during summer. The median of depth-integrated chl a concentration in summer was significantly higher than in winter. Integrated abundances of sympagic meiofauna were within the same range for both seasons and varied between 0.6 and 34.1×103 organisms /m**2 in summer and between 3.7 and 24.8×10**3 organisms /m**2 in winter. With regard to species composition, a comparison between the two seasons showed distinct differences: while copepods (42.7%) and rotifers (33.4%) were the most abundant sea-ice meiofaunal taxa during summer, copepod nauplii dominated the community, comprising 92.9% of the fauna, in winter. Low species abundances were found in the under-ice water, indicating that overwintering of the other sympagic organisms did not take place there, either. Therefore, their survival strategy over the polar winter remains unclear.

Smear slide analysis of sediment core GeoB5836-2

Laminated sediments spanning the last 20,000 years (though not continuously) in the Shaban Deep, a brine-filled basin in the northern Red Sea, were analyzed microscopically and with backscattered electron imagery in order to determine laminae composition with emphasis on the diatomaceous component. Based on this detailed study, we present schematic models to propose paleoflux scenarios for laminae formation at different time-slices. The investigated core (GeoB 5836-2; 26°12.61'N, 35°21.56'E; water depth 1475 m) shows light and dark alternating laminae that are easily distinguishable in the mid-Holocene and at the end of the deglaciation (13-15 ka) period. Light layers are mainly composed of coccoliths, terrigenous material and diatom fragments, while dark layers consist almost exclusively of diatom frustules (monospecific or mixed assemblages). The regularity in the occurrence of coccolith/diatom couplets points to an annual deposition cycle where contrasting seasons and associated plankton blooms are represented (diatoms-fall/winter deposition, coccoliths-summer signal). We propose that, for the past ~15,000 years, the laminations represent two-season annual varves. Strong dissolution of carbonate, with the concomitant loss of the coccolith-rich layer in sediments older than 15 ka, prevents us from presenting a schematic model of annual deposition. However, the diatomaceous component reveals a marked switch in species composition between Last Glacial Maximum (LGM) sediments (dominated by Chaetoceros resting spores) and sediments somewhat younger (18-19 ka; dominated by Rhizosolenia). We propose that different diatom assemblages reflect changing conditions in stratification in the northern Red Sea: Strong stratification conditions, such as during two meltwater pulses at 14.5 and 11.4 ka, are reflected in the sediment by Rhizosolenia layers, while Chaetoceros-dominated assemblages represent deep convection conditions.

Siliceous phytoplankton fluxes off northwest Africa

Four years of observations (1988-1991) of downward fluxes of diatoms and silicoflagellates at a trap site off Cape Blanc (ca. 20°N, 20°W), northwest Africa, are presented. Significant variations in flux and species composition were observed as well as a marked drop in the export of biogenic opal (and diatoms) from 1988 to 1989; fluxes remained low thereafter. We hypothesize that this diminution might be related to decreased coastal upwelling intensity and offshore spreading of the typical chlorophyll filament, and/or a lesser silicate content of upwelling waters off Cape Blanc. In addition, the more seaward positioning of the mooring may have influenced the fluxes. At all times, diatoms were the most prominent contributors to the biogenic opal flux, and diatom fluxes closely paralleled total mass flux fluctuations. Although species composition varied seasonally, no significant qualitative variations were observed from year to year. In general, the dominance of neritic diatoms, such as Thalassionema nitzschioides var. nitzschioides, resting spores of Chaetoceros and Cyclotella litoralis, reflected the continuous offshore influence of coastal upwelling at the Cape Blanc trap site, with stronger intensity in spring/summer. In contrast, the occurrence of pelagic diatoms (e.g. Nitzschia bicapitata, N. interruptestriata, T. nitzschioides var. parva and Fragilariopsis doliolus), and high silicoflagellate fluxes (mainly Dictyocha messanensis) were linked to inshore transport of oceanic waters, generally in winter. With the exception of some fragile, pelagic diatoms, dominant species found in the settled material also occurred in the underlying sediments, suggesting that diatom thanatocoenosis downcore (Organisms preserved from the top to the bottom in sediment core) can be used as a reliable indicator of the intensity and persistence of the offshore spreading of coastal upwelling.

Organic-walled dinoflagellate cysts and environmental analysis of surface sediments from the Northwest African upwelling area

In order to examine the spatial distribution of organic-walled dinoflagellate cysts (dinocysts) in recent sediments related to environmental conditions in the water column, thirty-two surface sediment samples from the NW African upwelling region (20-32°N) were investigated. Relative abundances of the dinocyst species show distinct regional differences allowing the separation of four hydrographic regimes. (1) In the area off Cape Ghir, which is characterized by most seasonal upwelling and river discharge, Lingulodinium machaerophorum strongly dominates the associations which are additionally characterized by cysts of Gymnodinium nolleri, cysts of Polykrikos kofoidii and cysts of Polykrikos schwartzii. (2) Off Cape Yubi, a region with increasing perennial upwelling, L. machaerophorum, Brigantedinium spp., species of the genus Impagidinium and cysts of Protoperidinium stellatum occur in highest relative abundances. (3) In coastal samples between Cape Ghir and Cape Yubi, Gymnodinium catenatum, species of the genus Impagidinium, Nematosphaeropsis labyrinthus, Operculodinium centrocarpum, cysts of P. stellatum and Selenopemphix nephroides determine the species composition. (4) Off Cape Blanc, where upwelling prevails perennially, and at offshore sites, heterotrophic dinocyst species show highest relative abundances. A Redundancy Analysis reveals fluvial mud, sea surface temperature and the depth of the mixed layer in boreal spring (spring) as the most important parameters relating to the dinocyst species association. Dinocyst accumulation rates were calculated for a subset of samples using well-constrained sedimentation rates. Highest accumulation rates with up to almost 80.000 cysts cm**-2 ky**-1 were found off Cape Ghir and Cape Yubi reflecting their eutrophic upwelling filaments. A Redundancy Analysis gives evidence that primary productivity and the input of fluvial mud are mostly related to the dinocyst association. By means of accumulation rate data, quantitative cyst production of individual species can be considered independently from the rest of the association, allowing autecological interpretations. We show that a combined interpretation of relative abundances and accumulation rates of dinocysts can lead to a better understanding of the productivity conditions off NW Africa.

Benthic foraminifera in surface sediments, South Atlantic

Sixty surface sediment samples from the eastern South Atlantic Ocean including the Walvis Ridge, the Angola and Cape basins, and the Southwest African continental margin were analysed for their benthic foraminiferal content to unravel faunal distribution patterns and ecological preferences. Live (stained with Rose Bengal) and dead faunas were counted separately and then each grouped by Q-mode principal component analysis into seven principal faunal end-members. Then, multiple regression technique was used to correlate Recent assemblages with available environmental variables and to finally differentiate between four principal groups of environmental agents acting upon the generation of benthic foraminiferal assemblages: (1) seasonality of food supply and organic carbon flux rates, together with oxygen content in the pore and bottom waters; (2) lateral advection of deep-water masses; (3) bottom water carbonate corrosiveness; and (4) energetic state at the benthic boundary layer and grain size composition of the substrate. Food supply and corresponding dissolved oxygen contents in the pore and bottom waters turned out to be the most important factors which control the distribution pattern of the Recent benthic foraminifera. At the continental margin, in the zone of coastal upwelling and its mixing area, benthic foraminiferal assemblages are dominated by stenobathic high-productivity faunas, characterized by elevated standing stocks, low diversities and a large number of endobenthic living species. At the continental shelf and upper continental slope the live assemblages are characterized by Rectuvigerina cylindrica, Uvigerina peregrina s.1., Uvigerina auberiana and Rhizammina spp. while the dead assemblages are characterized by Cassidulina laevigata, Bolivina dilatata, Bulimina costata and B. mexicana. At the lower continental slope strong influence of high organic matter fluxes on the species composition is restricted to the area off the Cunene river mouth, where the live assemblage is dominated by Uvigerina peregrina s.1., the corresponding dead assemblage by Melonis barleeanum and M. zaandamae. In the adjacent areas of the lower continental slope the biocoenosis is characterized by Reophax bilocularis, and Epistominella exigua which becomes dominant in the corresponding dead assemblage. At the Walvis Ridge and in the abyssal Angola and Cape basins, where organic matter fluxes are low and highly seasonal, benthic foraminiferal assemblages reflect both the oligotrophic situation and the deep and bottom water mass configuration. The top and flanks of the Walvis Ridge are inhabited by the Rhizammina, Psammosphaera and R. bilocularis live assemblages, the corresponding dead assemblages are dominated by G. subglobosa on the ridge top and E. exigua on the flanks. Within the highly diverse E. exigua dead assemblage several associated epibenthic species coincide with the core of NADW between about 1600 and 3700 m water depth. These species include Osangularia culter, Cibicidoides kullenbergi, Melonis pompilioides, Bolivinita pseudothalmanni and Bulimina alazanensis. The assemblages of the abyssal Cape and Angola basins are characterized by Nuttallides umbonifer and a high proportion of agglutinated species. These species are adapted to very low organic matter fluxes and a carbonate corrosive environment.

Presence of competitors influences photosynthesis, but not growth, of the hard coral Porites cylindrica at elevated seawater CO2

Changes in environmental conditions, such as those caused by elevated carbon dioxide (CO2), potentially alter the outcome of competitive interactions between species. This study aimed to understand how elevated CO2 could influence competitive interactions between hard and soft corals, by investigating growth and photosynthetic activity of Porites cylindrica (a hard coral) under elevated CO2 and in the presence of another hard coral and two soft coral competitors. Corals were collected from reefs around Orpheus and Pelorus Islands on the Great Barrier Reef, Australia. They were then exposed to elevated pCO2 for 4 weeks with two CO2 treatments: intermediate (pCO2 648) and high (pCO2 1003) compared with a control (unmanipulated seawater) treatment (pCO2 358). Porites cylindrica growth did not vary among pCO2 treatments, regardless of the presence and type of competitors, nor was the growth of another hard coral species, Acropora cerealis, affected by pCO2 treatment. Photosynthetic rates of P. cylindrica were sensitive to variations in pCO2, and varied between the side of the fragment facing the competitors vs. the side facing away from the competitor. However, variation in photosynthetic rates depended on pCO2 treatment, competitor identity, and whether the photosynthetic yields were measured as maximum or effective photosynthetic yield. This study suggests that elevated CO2 may impair photosynthetic activity, but not growth, of a hard coral under competition and confirms the hypothesis that soft corals are generally resistant to elevated CO2. Overall, our results indicate that shifts in the species composition in coral communities as a result of elevated CO2 could be more strongly related to the individual tolerance of different species rather than a result of competitive interactions between species.