Seawater carbonate chemistry and calcium carbonate of Padina spp., photosynthesis of Padina pavonica in nature CO2 gradients experiment

Predicting the impacts of ocean acidification on coastal ecosystems requires an understanding of the effects on macroalgae and their grazers, as these underpin the ecology of rocky shores. Whilst calcified coralline algae (Rhodophyta) appear to be especially vulnerable to ocean acidification, there is a lack of information concerning calcified brown algae (Phaeophyta), which are not obligate calcifiers but are still important producers of calcium carbonate and organic matter in shallow coastal waters. Here, we compare ecological shifts in subtidal rocky shore systems along CO2 gradients created by volcanic seeps in the Mediterranean and Papua New Guinea, focussing on abundant macroalgae and grazing sea urchins. In both the temperate and tropical systems the abundances of grazing sea urchins declined dramatically along CO2 gradients. Temperate and tropical species of the calcifying macroalgal genus Padina (Dictyoaceae, Phaeophyta) showed reductions in CaCO3 content with CO2 enrichment. In contrast to other studies of calcified macroalgae, however, we observed an increase in the abundance of Padina spp. in acidified conditions. Reduced sea urchin grazing pressure and significant increases in photosynthetic rates may explain the unexpected success of decalcified Padina spp. at elevated levels of CO2. This is the first study to provide a comparison of ecological changes along CO2 gradients between temperate and tropical rocky shores. The similarities we found in the responses of Padina spp. and sea urchin abundance at several vent systems increases confidence in predictions of the ecological impacts of ocean acidification over a large geographical range.

Abundance of mesozooplankton in the north-eastern Black Sea during SESRU02 cruise in September 2008

The SESRU_02_mesozooplankton dataset contains data collected in September 2008 at 15 stations located between 37°E and 39.5°E and between 42.4°N and 44.5°N in the north-eastern Black Sea. Samples were collected with a Juday net. Juday net: Vertical tows of a closing Juday net, with mouth area 0.1 m**2, mesh size 180 µm. Samples were taken from different layers. Towing speed: 1m/s. Samples were preserved by a 4% formaldehyde sea water buffered solution. Sampling volume was estimated by multiplying the mouth area with the wire length. Integrated samples were taken from the lower boundary of the oxic zone to the surface, stratified samples were taken according to CTD-profiles: samples were taken from the following depth strata: 1) the upper mixed layer (UML); 2) the layer of high temperature gradients (from the upper boundary of thermocline to the depth of 8 deg C temperature); 3) cold Intermediate layer (CIL) - the layer with the T< 8 deg C; 4) from the depth of sigma theta = 15.8 (oxycline) to the lower boundary of CIL; 5) from the depth of sigma theta = 16.2 to the depth of sigma theta = 15.8. Samples were analysed for zooplankton species and stage composition and abundance. The entire sample or an aliquot (1/2 to ¼) was analyzed under the binocular microscope. Mesozooplankton species and stages were identified and enumerated; meroplankton were identified and enumerated at higher taxonomic level. Taxonomic identification was done at Shirshov Institute of Oceanology using the relevant taxonomic literature (Rose, 1933, Brodsky, 1950 and Internet resources).

Abundance of mesozooplankton in the north-eastern Black Sea during SESRU01 cruise in April 2008

The SESRU01_mesozooplankton dataset contains data collected in April 2008 at 19 stations located between 37°E and 39.5°E and between 42.4°N and 44.5°N in the north-eastern Black Sea. Samples were collected with a Juday net (mesh size 180 ?m, mouth area 0.1 m**2). Integrated samples were taken from the lower boundary of the oxic zone to the surface, stratified samples were taken according to CTD-profiles: samples were taken from the following depth strata: 1) the upper mixed layer (UML); 2) the layer of high temperature gradients (from the upper boundary of thermocline to the depth of 8 deg C temperature); 3) cold Intermediate layer (CIL) - the layer with the T< 8 deg C; 4) from the depth of sigma theta = 15.8 (oxycline) to the lower boundary of CIL; 5) from the depth of sigma theta = 16.2 to the depth of sigma theta = 15.8. Samples were analysed for zooplankton species and stage composition and abundance. Juday net: Vertical tows of a closing Juday net, with mouth area 0.1 m**2, mesh size 180µm. Samples were taken from different layers. Towing speed: 1m/s. Samples were preserved by a 4% formaldehyde sea water buffered solution. Sampling volume was estimated by multiplying the mouth area by the wire length. The entire sample or an aliquot (1/2 to1/4) was analyzed under the binocular microscope. Mesozooplankton species and stages were identified and enumerated; meroplankton were identified and enumerated at higher taxonomic level. Taxonomic identification was done at Shirshov Institute of Oceanology using the relevant taxonomic literature (Rose, 1933, Brodsky, 1950, and Internet resources).

Abundance and biomass of phytoplankton in the western part of the Black Sea during Parshin cruise BSRP in September and October 2005

The dataset is composed of 61 samples from 15 stations. The phytoplankton samples were collected by 5l Niskin bottles attached to the CTD system. The sampling depths were selected according to the CTD profile and the in situ fluorometer readings: surface, temperature, salinity and fluorescence gradients and 1 m above the bottom. At some stations phytoplankton net samples (20 µm mesh-size) were collected to assist species biodiversity examination. The samples (1l sea water) were preserved in 4% buffered to pH 8-8.2 with disodiumtetraborate formaldehyde solution and stored in plastic containers. On board at each station few live samples were qualitatively examined under microscope for preliminary analysis of taxonomic composition and dominant species. Taxon-specific phytoplankton abundance were concentrated down to 50 cm**3 by slow decantation after storage for 20 days in a cool and dark place. The species identification was done under light microscope OLIMPUS-BS41 connected to a video-interactive image analysis system at magnification of the ocular 10X and objective - 40X. A Sedgwick-Rafter camera (1ml) was used for counting. 400 specimen were counted for each sample, while rare and large species were checked in the whole sample (Manual of phytoplankton, 2005). Species identification was mainly after Carmelo T. (1997) and Fukuyo, Y. (2000). The cell biovolume of the taxon-specific phytoplankton biomass was determined based on morpho-metric measurement of phytoplankton units and the corresponding geometric shapes as described in detail in (Edier, 1979).

Abundance and biomass of phytoplankton in the western part of the Black Sea during the R/V Akademik cruise Ak082001 in August 2001

The dataset is composed of 41 samples from 10 stations. The phytoplankton samples were collected by 5l Niskin bottles attached to the CTD system. The sampling depths were selected according to the CTD profile and the in situ fluorometer readings: surface, temperature, salinity and fluorescence gradients and 1 m above the bottom. At some stations phytoplankton net samples (20 µm mesh-size) were collected to assist species biodiversity examination. The samples (1l sea water) were preserved in 4% buffered to pH 8-8.2 with disodiumtetraborate formaldehyde solution and stored in plastic containers. On board at each station few live samples were qualitatively examined under microscope for preliminary analysis of taxonomic composition and dominant species. The taxon-specific phytoplankton abundance samples were concentrated down to 50 cm**3 by slow decantation after storage for 20 days in a cool and dark place. The species identification was done under light microscope OLIMPUS-BS41 connected to a video-interactive image analysis system at magnification of the ocular 10X and objective - 40X. A Sedgwick-Rafter camera (1ml) was used for counting. 400 specimen were counted for each sample, while rare and large species were checked in the whole sample (Manual of phytoplankton, 2005). Species identification was mainly after Carmelo T. (1997) and Fukuyo, Y. (2000). Total phytoplankton abundance was calculated as sum of taxon-specific abundances. Total phytoplankton biomass was calculated as sum of taxon-specific biomasses. The cell biovolume was determined based on morpho-metric measurement of phytoplankton units and the corresponding geometric shapes as described in detail in (Edier, 1979).

Water quality monitoring: A combined approach to investigate gradients of change in the Great Barrier Reef, Australia

For the managers of a region as large as the Great Barrier Reef, it is a challenge to develop a cost effective monitoring program, with appropriate temporal and spatial resolution to detect changes in water quality. The current study compares water quality data (phytoplankton abundance and water clarity) from remote sensing with field sampling (continuous underway profiles of water quality and fixed site sampling) at different spatial scales in the Great Barrier Reef north of Mackay (20 degrees S). Five transects (20-30 km long) were conducted from clean oceanic water to the turbid waters adjacent to the mainland. The different data sources demonstrated high correlations when compared on a similar spatial scale (18 fixed sites). However, each data source also contributed unique information that could not be obtained by the other techniques. A combination of remote sensing, underway sampling and fixed stations will deliver the best spatial and temporal monitoring of water quality in the Great Barrier Reef. (c) 2004 Elsevier Ltd. All rights reserved.

Epiphyte loads on seagrasses and microphytobenthos abundance are not reliable indicators of nutrient availability in oligotrophic coastal ecosystems

Despite marked gradients in nutrient availability that control the abundance and species composition of seagrasses in south Florida, and the importance of nutrient availability in controlling abundance and composition of epiphytes on seagrasses in other locations, we did not find that epiphyte load on the dominant seagrass, Thalassia testudinum, or that the relative contribution of algal epiphytes to the epiphyte community, was positively correlated with nutrient availability in the water column or the sediment in oligotrophic seagrass beds. Further, the abundance of microphytobenthos, as indicated by Chlorophyll-aconcentration in the sediments, was not directly correlated with concentrations of nutrients in the sediments. Our results suggest that epiphyte and microphytobenthos abundance are not unambiguous indicators of nutrient availability in relatively pristine seagrass environments, and therefore would make poor candidates for indicators of the status and trends of seagrass ecosystems in relatively low-nutrient environments like the Florida Keys.

Diatom-based Models for Inferring Hydrology and Periphyton Abundance in a Subtropical Karstic Wetland: Implications for Ecosystem-Scale Bioassessment

We developed diatom-based prediction models of hydrology and periphyton abundance to inform assessment tools for a hydrologically managed wetland. Because hydrology is an important driver of ecosystem change, hydrologic alterations by restoration efforts could modify biological responses, such as periphyton characteristics. In karstic wetlands, diatoms are particularly important components of mat-forming calcareous periphyton assemblages that both respond and contribute to the structural organization and function of the periphyton matrix. We examined the distribution of diatoms across the Florida Everglades landscape and found hydroperiod and periphyton biovolume were strongly correlated with assemblage composition. We present species optima and tolerances for hydroperiod and periphyton biovolume, for use in interpreting the directionality of change in these important variables. Predictions of these variables were mapped to visualize landscape-scale spatial patterns in a dominant driver of change in this ecosystem (hydroperiod) and an ecosystem-level response metric of hydrologic change (periphyton biovolume). Specific diatom assemblages inhabiting periphyton mats of differing abundance can be used to infer past conditions and inform management decisions based on how assemblages are changing. This study captures diatom responses to wide gradients of hydrology and periphyton characteristics to inform ecosystem-scale bioassessment efforts in a large wetland.

Distribution of Diatoms Along Environmental Gradients in the Charlotte Harbor, Florida (USA), Estuary and Its Watershed: Implications for Bioassessment of Salinity and Nutrient Concentrations

The relative abundance of diatom species in different habitats can be used as a tool to infer prior environmental conditions and evaluate management decisions that influence habitat quality. Diatom distribution patterns were examined to characterize relationships between assemblage composition and environmental gradients in a subtropical estuarine watershed. We identified environmental correlates of diatom distribution patterns across the Charlotte Harbor, Florida, watershed; evaluated differences among three major river drainages; and determined how accurately local environmental conditions can be predicted using inference models based on diatom assemblages. Sampling locations ranged from freshwater to marine (0.1–37.2 ppt salinity) and spanned broad nutrient concentration gradients. Salinity was the predominant driver of difference among diatom assemblages across the watershed, but other environmental variables had stronger correlations with assemblages within the subregions of the three rivers and harbor. Eighteen indicator taxa were significantly affiliated with subregions. Relationships between diatom taxon distributions and salinity, distance from the harbor, total phosphorus (TP), and total nitrogen (TN) were evaluated to determine the utility of diatom assemblages to predict environmental values using a weighted averaging-regression approach. Diatom-based inferences of these variables were strong (salinity R 2 = 0.96; distance R 2 = 0.93; TN R 2 = 0.83; TP R 2 = 0.83). Diatom assemblages provide reliable estimates of environmental parameters on different spatial scales across the watershed. Because many coastal diatom taxa are ubiquitous, the diatom training sets provided here should enable diatom-based environmental reconstructions in subtropical estuaries that are being rapidly altered by land and water use changes and sea level rise.

Macroinvertebrate abundance in tropical Andean streams, Ecuador

Deforestation in the tropical Andes is affecting ecological conditions of streams, and determination of how much forest should be retained is a pressing task for conservation, restoration and management strategies. We calculated and analyzed eight benthic metrics (structural, compositional and water quality indices) and a physical-chemical composite index with gradients of vegetation cover to assess the effects of deforestation on macroinvertebrate communities and water quality of 23 streams in southern Ecuadorian Andes. Using a geographical information system (GIS), we quantified vegetation cover at three spatial scales: the entire catchment, the riparian buffer of 30 m width extending the entire stream length, and the local scale defined for a stream reach of 100 m in length and similar buffer width. Macroinvertebrate and water quality metrics had the strongest relationships with vegetation cover at catchment and riparian scales, while vegetation cover did not show any association with the macroinvertebrate metrics at local scale. At catchment scale, the water quality metrics indicate that ecological condition of Andean streams is good when vegetation cover is over 70%. Further, macroinvertebrate community assemblages were more diverse and related in catchments largely covered by native vegetation (>70%). Overall, our results suggest that retaining an important quantity of native vegetation cover within the catchments and a linkage between headwater and riparian forests help to maintain and improve stream biodiversity and water quality in Andean streams affected by deforestation. Also, this research proposes that a strong regulation focused to the management of riparian buffers can be successful when decision making is addressed to conservation/restoration of Andean catchments.

Environmental data from coastal sediments along natural CO2 gradients at a volcanic vent in Papua New Guinea

Natural CO2 venting systems can mimic conditions that resemble intermediate to high pCO2 levels as predicted for our future oceans. They represent ideal sites to investigate potential long-term effects of ocean acidification on marine life. To test whether microbes are affected by prolonged exposure to pCO2 levels, we examined the composition and diversity of microbial communities in oxic sandy sediments along a natural CO2 gradient. Increasing pCO2 was accompanied by higher bacterial richness and by a strong increase in rare members in both bacterial and archaeal communities. Microbial communities from sites with CO2 concentrations close to today's conditions had different structures than those of sites with elevated CO2 levels. We also observed increasing sequence abundance of several organic matter degrading types of Flavobacteriaceae and Rhodobacteraceae, which paralleled concurrent shifts in benthic cover and enhanced primary productivity. With increasing pCO2, sequences related to bacterial nitrifying organisms such as Nitrosococcus and Nitrospirales decreased, and sequences affiliated to the archaeal ammonia-oxidizing Thaumarchaeota Nitrosopumilus maritimus increased. Our study suggests that microbial community structure and diversity, and likely key ecosystem functions, may be altered in coastal sediments by long-term CO2 exposure to levels predicted for the end of the century.

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)

Viral, bacterial and ciliate abundance and viral-bacterial diversity in mesocosm experiments, 2007-2008, Kongsfjorden

Two mesocosm experiments, PAME-I and PAME-II were conducted in 2007 and 2008 to investigate fate of organic carbon in the arctic microbial food web. Mesocosms were nutrient fertilized initially to induce phytoplankton bloom development. In PAME-I eight units (each 700 L) formed two four point gradients of additional DOC in form of glucose (0, 0.5, 1 and 3 times Redfield ratio in terms of carbon relative to the nitrogen and phosphorus additions) (Fig. 1). All the eight units also got a daily dose of NH4+ and PO4**3- in Redfield ratio. Two gradients were set up, one with silicate addition, performed in the Arctic location Ny Ålesund, Svalbard, have previously been reported to give different food-web level responses to similar nutrient perturbations. In PAME-II all ten units (each 900 L) formed two four point gradients of additional DOC in form of glucose (0, 0.5, 1, 2 and 3 times Redfield ratio in terms of carbon relative to nitrogen and phosphorus additions). The two gradients in glucose were kept silicate replete. NH4+ was used as the DIN source in one gradient (units 1 to 5) and NO3- in the other (units 6-9). All units got a daily dose of PO4**3- in Redfield ratio. Prokaryotes and viruses were measured by flow cytometry, while ciliate abundances were counted using a Flow Cam. Viral and bacterial diversity was measured by PFGE and DGGE, respectively. In PAME-II the abundance of ciliates was lower than in PAME-I, presumably caused by higher copepod grazing. The abundances of prokaryotes and viruses were also lower in PAME-II compared to PAME-I. Further, less diversity was detected in the viral community (FCM and PFGE) in PAME-II, and no response was observed in the bacterial community structure due to addition of organic carbon.

Influence of host plant structure and microclimate on the abundance and behaviour of Tephritid fly

Microclimate and host plant architecture significantly influence the abundance and behavior of insects. However, most research in this field has focused at the invertebrate assemblage level, with few studies at the single-species level. Using wild Solanum mauritianum plants, we evaluated the influence of plant structure (number of leaves and branches and height of plant) and microclimate (temperature, relative humidity, and light intensity) on the abundance and behavior of a single insect species, the monophagous tephritid fly Bactrocera cacuminata (Hering). Abundance and oviposition behavior were signficantly influenced by the host structure (density of foliage) and associated microclimate. Resting behavior of both sexes was influenced positively by foliage density, while temperature positively influenced the numbers of resting females. The number of ovipositing females was positively influenced by temperature and negatively by relative humidity. Feeding behavior was rare on the host plant, as was mating. The relatively low explanatory power of the measured variables suggests that, in addition to host plant architecture and associated microclimate, other cues (e.g., olfactory or visual) could affect visitation and use of the larval host plant by adult fruit flies. For 12 plants observed at dusk (the time of fly mating), mating pairs were observed on only one tree. Principal component analyses of the plant and microclimate factors associated with these plants revealed that the plant on which mating was observed had specific characteristics (intermediate light intensity, greater height, and greater quantity of fruit) that may have influenced its selection as a mating site.