37 research outputs found
Shifts in historical streamflow extremes in the Colorado River Basin
No full textThe global phenomenon of climate change-induced shifts in precipitation leading to “wet regions getting wetter” and “dry regions getting drier” has been widely studied. However, the propagation of these changes in atmospheric moisture within stream channels is not a direct relationship due to differences in the timing of how changing precipitation patterns interact with various land surfaces. Streamflow is of particular interest in the Colorado River Basin (CRB) due to the region’s rapidly growing population, projected temperature increases that are expected to be higher than elsewhere in the contiguous United States, and subsequent climate-driven disturbances including drought, vegetation mortality, and wildfire, which makes the region more vulnerable to changes in hydrologic extremes. Here, we determine how streamflow extremes have shifted in the CRB using two statistical methods—the Mann-Kendall trend detection analysis and Generalized Extreme Value (GEV) theorem. We evaluate these changes in the context of key flow metrics that include high and low flow percentiles, maximum and minimum 7-day flows, and the center timing of streamflow using historical gage records representative of natural flows. Monthly results indicate declines of up to 41% for high and low flows during the June to July peak runoff season, while increases of up to 24% were observed earlier from March to April. Our results highlight a key threshold elevation and latitude of 2300 m and 39° North, respectively, where there is a distinct shift in the trend. The spatiotemporal patterns observed are indicative of changing snowmelt patterns as a primary cause of the shifts. Identification of how this change varies spatially has consequences for improved land management strategies, as specific regions most vulnerable to threats can be prioritized for mitigation or adaptation as the climate warms
Oceanic Shoals Commonwealth Marine Reserve - Chlorophyll a, b and c and phaeophytin a concentrations in seabed sediments.
No full textMaintenance and Update Frequency: asNeededStatement: Bottom sediments were collected using either a Smith McIntyre grab or a Box Core. 0.4 ml samples of surface sediment (0-0.5 cm) were syringed into plastic bags. The samples were wrapped in Al foil and frozen. Chlorophyll concentrations were calculated on sediment extracts (90% acetone + 0.1% MgCO3) at spectrophometric readings at wavelengths of 647, 630, 750 and 664 nm. For chlorophyll-a (Chl-a) and phaeophytin-a, wavelengths of 664 nm and 750 nm (before and after the addition of 200 -L-1 0.1 mol L-1 HCl per 2 mL extractant) and the equation derived by Lorenzen (1967) were used. Chlorphyll b and c concentrations were calculated according to equations provided by Jeffrey and Welschmeyer (2003). The reproducibility of the measurements was +/-10%.
Thanks to the crew of the RV Solander for help with sample collection.
Lorenzen, C. J. (1967). Determination of chlorophyll and pheopigments: Spectrophotometric equations. Limnology and Oceanography 12, 343-346.
Jeffrey, S.W., and Welschmeyer, N.A. (2003). Spectrophotometric and fluorometric equations in common use in oceanography. In 'Phytoplankton pigments in oceanography: guidelines to modern methods' (Eds. S.W. Jeffrey and R.F.C. Mantoura, and S.W. Wright.) pp. 597-615. (UNESCO Paris.)This resource contains geochemistry data for the Oceanic Shoals Commonwealth Marine Reserve (CMR) in the Timor Sea collected by Geoscience Australia during September and October 2012 on RV Solander (survey GA0339/SOL5650). This datset comprises chlorophyll a, b and c and phaeophytin a concentrations from the upper 2 cm of seabed sediments. The Oceanic Shoals Commonwealth Marine Reserve survey was undertaken as an activity within the Australian Government's National Environmental Research Program Marine Biodiversity Hub and was the key component of Research Theme 4 - Regional Biodiversity Discovery to Support Marine Bioregional Plans. Hub partners involved in the survey included the Australian Institute of Marine Science, Geoscience Australia, the University of Western Australia, Museum Victoria and the Museum and Art Gallery of the Northern Territory. Data acquired during the survey included: multibeam sonar bathymetry and acoustic backscatter; sub-bottom acoustic profiles; physical samples of seabed sediments, infauna and epibenthic biota; towed underwater video and still camera observations of seabed habitats; baited video observations of demersal and pelagic fish, and; oceanographic measurements of the water column from CTD (conductivity, temperature, depth) casts and from deployment of sea surface drifters. Further information on the survey is available in the post-survey report published as Geoscience Australia Record 2013/38: Nichol, S.L., Howard, F.J.F., Kool, J., Stowar, M., Bouchet, P., Radke, L.,<br/>Siwabessy, J., Przeslawski, R., Picard, K., Alvarez de Glasby, B., Colquhoun, J., Letessier, T. &<br/>Heyward, A. 2013. Oceanic Shoals Commonwealth Marine Reserve (Timor Sea) Biodiversity Survey:<br/>GA0339/SOL5650 - Post Survey Report. Record 2013/38. Geoscience Australia: Canberra. (GEOCAT #76658)
Corylus cornuta subsp. cornuta Marshall subsp. cornuta
No full text7a. Corylus cornuta Marshall subsp. cornuta Note: it has been recognized as having two subspecies by Flora of North America (Furlow 1997) and World Checklist and Bibliography of Fagales (Govaerts & Frodin 1998). C. rostrata Aiton, Hortus Kewensis 3: 364 (Aiton 1789). – Original citation: “Cult. [since] 1745 by Archibald Duke of Argyle” [sic!, Archibald Campbell, third Duke of Argyll, who laid the groundstock for Kew Botanical Gardens] and “Nat. of North America.” Material from the cited Gronovius (1762): “Crescit in Dragon swamps” [a river in Virginia, USA]. – Type: Cult., Hort. Bni [Botanici] Collinson, Mill Hill, s. coll., s.n. (neo-, designated here: BM001191197!). – Note: the first author did not find any original material in the relevant herbaria. In order to explore which material might be taken into account, we briefly discuss the origin of the name here. As there is no explicit indication of an author, the name is to be attributed to Aiton (Art 46.8. ICN, McNeill et al. 2012). However, the original author of C. rostrata is apparently Daniel Carlsson Solander. Although the third volume was mainly edited by Dryander (Stafleu & Cowan 1976 –1988), Dryander largely used Solander’s manuscripts (Britten 1912), and in the Linnean herbarium, there is a specimen of what is now understood as C. cornuta (LINN 1132.2) where J.E. Smith writes “ C. rostrata Mss. 83. 931” and “ C. rostrata Soland [er] Ait. H. Kew v.3 364.” As a contemporary of the publication, Smith likely knew who the author of the name was, while 81 and 931 might be interpreted as manuscript fragments. Therefore, possible original material needs to be linked to Solander’s collections. Two sources are cited in the protologue, material from Duke Argyll’s garden and Gronovius’ Flora Virginica ed. 2 (Gronovius 1762). Material from Gronovius is usually found in the Clayton Herbarium (Stafleu & Cowan 1976 –1988), but there appears to be no original material of this taxon. Also, the number cited for Clayton’s herbarium in Gronovius’ Flora Virginica ed. 2 is erroneous, because Clayton 747 is a Juglans sp., which is already cited on the previous page. There is a specimen in BM (BM001191197) by Peter Collinson (1694–1768) from Mill Hill, where Collinson lived from 1749 on (Living & Braithwaite 2013). Collinson obtained material from Gronovius for cultivation (Reveal & Pringle 1993), and Collinson was also in contact with Solander. Thus, the specimen might be derived from Gronovius’ collection. In addition, as a student of Linnaeus, Solander had access to his herbarium, so the LINN specimen (LINN 1132.2) might also be taken into consideration. However, neither Collinson’s specimen nor the one from the Linnean herbarium can unambiguously linked to Solander, so they are not original material, making a neotypification necessary. Due to be possible link and the completeness of the specimen, we choose the specimen from Collinson’s garden as neotype. C. cornuta f. inermis Fernald, Rhodora 38: 76 (Fernald 1936). – Original citation: “ Quebec: abundant in border of woods, East Broughton”. – Type: Canada, Quebec, East Broughton, 28 Aug. 1915, M.L. Fernald and H.B. Jackson 12073 (holo-: GH). C. cornuta var. megaphylla Vict. & Rousseau, Contributions de l’Institut Botanique de l’Universite de Montréal 36: 13 (Marie-Victorin & Rousseau 1940). – Type: Canada, Quebec, Matapédia, sur les îles de la Restigouche, à l’embouchure de la Matapédia (frontière du Nouveau-Brunswick), 15 Aug. 1928, J.L.C. Marie-Victorin and Rolland-Germain 28690 (lecto-, designated here: MT00132174!; isolecto-: MT00132175!). – Additional type material: Canada, Quebec, thickets and borders of woods, near mouth of Marsouin River (Gaspé Co.), 26 Jul. 1922, M.L. Fernald and A.S. Pease 25014 (syn-: MT00206842!). – Note: Marie-Victorin & Rousseau cited the two collections and mentioned that the type is in the herbarium of the Université de Montreal (MT). However, there are two specimens of Marie-Victorin and Rolland-Germain 28690 in MT, of which one is annotated as a type, and one specimen of Fernald and Pease 25014 (Geoffrey Hall, MT, pers. com.). The annotated specimen is here formally designated as lectotype.Published as part of Holstein, Norbert, Tamer, Sarah el & Weigend, Maximilian, 2018, The nutty world of hazel names - a critical taxonomic checklist of the genus Corylus (Betulaceae), pp. 1-45 in European Journal of Taxonomy 409 on page 21, DOI: 10.5852/ejt.2018.409, http://zenodo.org/record/378716
An investigation of the calcification response of the scleractinian coral Astrangia poculata to elevated pCO2 and the effects of nutrients, zooxanthellae and gender
No full text© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeosciences 9 (2012): 29-39, doi:10.5194/bg-9-29-2012.The effects of nutrients and pCO2 on zooxanthellate and azooxanthellate colonies of the temperate scleractinian coral Astrangia poculata (Ellis and Solander, 1786) were investigated at two different temperatures (16 °C and 24 °C). Corals exposed to elevated pCO2 tended to have lower relative calcification rates, as estimated from changes in buoyant weights. Experimental nutrient enrichments had no significant effect nor did there appear to be any interaction between pCO2 and nutrients. Elevated pCO2 appeared to have a similar effect on coral calcification whether zooxanthellae were present or absent at 16 °C. However, at 24 °C, the interpretation of the results is complicated by a significant interaction between gender and pCO2 for spawning corals.
At 16 °C, gamete release was not observed, and no gender differences in calcification rates were observed – female and male corals showed similar reductions in calcification rates in response to elevated CO2 (15% and 19% respectively). Corals grown at 24 °C spawned repeatedly and male and female corals exhibited two different growth rate patterns – female corals grown at 24 °C and exposed to CO2 had calcification rates 39% lower than females grown at ambient CO2, while males showed a non-significant decline of 5% under elevated CO2. The increased sensitivity of females to elevated pCO2 may reflect a greater investment of energy in reproduction (egg production) relative to males (sperm production). These results suggest that both gender and spawning are important factors in determining the sensitivity of corals to ocean acidification, and considering these factors in future research may be critical to predicting how the population structures of marine calcifiers will change in response to ocean acidification.This material is based upon work supported under a
National Science Foundation Graduate Research Fellowship, the
WHOI Ocean Life Institute, NSF OCE-1041106, and an International
Society for Reef Studies/Ocean Conservancy Fellowship
Seafloor environments of the eastern Timor Sea, Northern Australia: Chlorophyll a,b,c and pheaophytin a concentrations in seabed sediments.
No full textMaintenance and Update Frequency: asNeededStatement: Sediments were collected using either a Smith-McIntyre grab or a Shipek grab. For chlorophylls, 0.4 ml samples of surface sediment (0-0.5 cm) were syringed into plastic bags. The samples were wrapped in Al foil and frozen. Chlorophyll concentrations were calculated on sediment extracts (90% acetone + 0.1% MgCO3) at spectrophometric readings at wavelengths of 647, 630, 750 and 664 nm. For chlorophyll-a (Chl-a) and phaeophytin-a, wavelengths of 664 nm and 750 nm (before and after the addition of 200 -L-1 0.1 mol L-1 HCl per 2 mL extractant) and the equation derived by Lorenzen (1967) were used. Chlorphyll b and c concentrations were calculated according to equations provided by Jeffrey and Welschmeyer (2003). The reproducibility of the measurements is expected to be +/-10%. Lorenzen, C. J. (1967). Determination of chlorophyll and pheopigments: Spectrophotometric equations. Limnology and Oceanography 12, 343-346. Jeffrey, S.W., and Welschmeyer, N.A. (2003).
Thanks to the crew of the RV Solander for help with sample collection.The Timor Sea and its tropical marine environment support significant and growing economic activity including oil and gas exploration. To reduce uncertainty in decision making regarding the sustainable use and ongoing protection of these marine resources, environmental managers and resource users require sound scientific information on the composition and stability of seabed environments and their biological assemblages. Surveys SOL4934 and SOL5117 to the eastern Joseph Bonaparte Gulf were undertaken in August and September 2009 and July and August 2010 respectively, in collaboration with the Australian Institute of Marine Science, with research collaborations from the RAN Australian Hydrographic Office, the Geological Survey of Canada and the Museum and Art Gallery of the Northern Territory. The purpose of these surveys were to develop biophysical maps, and deliver data and information products pertaining to complex seabed environment of the Van Diemen Rise and identify potential geohazards and unique, sensitive environments that relate to offshore infrastructure. This dataset comprises chlorophyll a,b, and c, and phaeophytin a concentrations in the upper 2cm of seafloor sediments.<br/><br/><br/>Some relevant publications are listed below:<br/><br/>1. Heap, A.D., Przeslawski, R., Radke, L., Trafford, J., Battershill, C. and Shipboard Party. 2010. Seabed environments of the eastern Joseph Bonaparte Gulf, Northern Australia: SOL4934 Post Survey Report. Geoscience Australia Record 2010/09, pp.81.<br/>2. Anderson, T.J., Nichol, S., Radke, L., Heap, A.D., Battershill, C., Hughes, M., Siwabessy, P.J., Barrie, V., Alvarez de Glasby, B., Tran, M., Daniell, J. & Shipboard Party, 2011b. Seabed Environments of the Eastern Joseph Bonaparte Gulf, Northern Australia: GA0325/Sol5117 - Post-Survey Report. Geoscience Australia, Record 2011/08, 58pp.<br/>3. Radke, L.C., Li, J., Douglas, G., Przeslawski, R., Nichol, S, Siwabessy, J., Huang, Z., Trafford, J., Watson, T. and Whiteway, T. Characterising sediments of a tropical sediment-starved continental shelf using cluster analysis of physical and geochemical variables. Environmental Chemistry, in pres
Simulating Human Water Regulation: The Development of an Optimal Complexity, Climate-Adaptive Reservoir Management Model for an LSM
No full textAbstract
The widespread influence of reservoirs on global rivers makes representations of reservoir outflow and storage essential components of large-scale hydrology and climate simulations across the land surface and atmosphere. Yet, reservoirs have yet to be commonly integrated into earth system models. This deficiency influences model processes such as evaporation and runoff, which are critical for accurate simulations of the coupled climate system. This study describes the development of a generalized reservoir model capable of reproducing realistic reservoir behavior for future integration in a global land surface model (LSM). Equations of increasing complexity relating reservoir inflow, outflow, and storage were tested for 14 California reservoirs that span a range of spatial and climate regimes. Temperature was employed in model equations to modulate seasonal changes in reservoir management behavior and to allow for the evolution of management seasonality as future climate varies. Optimized parameter values for the best-performing model were generalized based on the ratio of winter inflow to storage capacity so a future LSM user can generate reservoirs in any grid location by specifying the given storage capacity. Model performance statistics show good agreement between observed and simulated reservoir storage and outflow for both calibration (mean normalized RMSE = 0.48; mean coefficient of determination = 0.53) and validation reservoirs (mean normalized RMSE = 0.15; mean coefficient of determination = 0.67). The low complexity of model equations that include climate-adaptive operation features combined with robust model performance show promise for simulations of reservoir impacts on hydrology and climate within an LSM
Seabed environments and shallow geology of the Leveque Shelf, Browse Basin, Western Australia - Chlorophyll a, b, and c and phaeophytin a of seabed sediments.
No full textMaintenance and Update Frequency: asNeededStatement: Bottom sediments were collected using either a Smith Macintyre grab or a Shipek grab. 0.4 ml samples of surface sediment (0-0.5 cm) were syringed into plastic bags. The samples were wrapped in Al foil and frozen. Chlorophyll concentrations were calculated on sediment extracts (90% acetone + 0.1% MgCO3) at spectrophometric readings at wavelengths of 647, 630, 750 and 664 nm. For chlorophyll-a (Chl-a) and phaeophytin-a, wavelengths of 664 nm and 750 nm (before and after the addition of 200 -L-1 0.1 mol L-1 HCl per 2 mL extractant) and the equation derived by Lorenzen (1967) were used. Chlorphyll b and c concentrations were calculated according to equations provided by Jeffrey and Welschmeyer (2003). The reproducibility of the measurements is +/-10%.
Lorenzen, C. J. (1967). Determination of chlorophyll and pheopigments: Spectrophotometric equations. Limnology and Oceanography 12, 343-346.
Jeffrey, S.W., and Welschmeyer, N.A. (2003). Spectrophotometric and fluorometric equations in common use in oceanography. In 'Phytoplankton pigments in oceanography: guidelines to modern methods' (Eds. S.W. Jeffrey and R.F.C. Mantoura, and S.W. Wright.) pp. 597-615. (UNESCO Paris.)
Thanks to the crew of the RV Solander for help with sample acquisition.Geoscience Australia undertook a marine survey of the Leveque Shelf (survey number SOL5754/GA0340), a sub-basin of the Browse Basin, in May 2013. This survey provides seabed and shallow geological information to support an assessment of the CO2 storage potential of the Browse sedimentary basin. The basin, located on the Northwest Shelf, Western Australia, was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. The survey was undertaken under the Australian Government's National CO2 Infrastructure Plan (NCIP) to help identify sites suitable for the long term storage of CO2 within reasonable distances of major sources of CO2 emissions. The principal aim of the Leveque Shelf marine survey was to look for evidence of any past or current gas or fluid seepage at the seabed, and to determine whether these features are related to structures (e.g. faults) in the Leveque Shelf area that may extend to the seabed. The survey also mapped seabed habitats and biota to provide information on communities and biophysical features that may be associated with seepage. This research, combined with deeper geological studies undertaken concurrently, addresses key questions on the potential for containment of CO2 in the basin's proposed CO2 storage unit, i.e. the basal sedimentary section (Late Jurassic and Early Cretaceous), and the regional integrity of the Jamieson Formation (the seal unit overlying the main reservoir). This dataset comprises total chlorin concentrations and chlorin indices from the upper 2cm of seabed sediments
