Search

Your search keyword '"Mariash, Heather"' showing total 38 results
Start Over Author "Mariash, Heather" Publication Year Range Last 50 years

Refine your results

more »

more »

more »

more »
38 results on '"Mariash, Heather"'

1. Anoxia begets anoxia: a positive feedback to the deoxygenation of temperate lakes

Author

Lewis, Abigail S.L., Lau, Maximilian P., Jane, Stephen F., Rose, Kevin C., Be'eri‐Shlevin, Yaron, Burnet, Sarah H., Clayer, François, Feuchtmayr, Heidrun, Grossart, Hans‐Peter, Howard, Dexter W., Mariash, Heather, Delgado Martin, Jordi, North, Rebecca L., Oleksy, Isabella, Pilla, Rachel M., Smagula, Amy P., Sommaruga, Ruben, Steiner, Sara E., Verburg, Piet, Wain, Danielle, Weyhenmeyer, Gesa A., Carey, Cayelan C., Lewis, Abigail S.L., Lau, Maximilian P., Jane, Stephen F., Rose, Kevin C., Be'eri‐Shlevin, Yaron, Burnet, Sarah H., Clayer, François, Feuchtmayr, Heidrun, Grossart, Hans‐Peter, Howard, Dexter W., Mariash, Heather, Delgado Martin, Jordi, North, Rebecca L., Oleksy, Isabella, Pilla, Rachel M., Smagula, Amy P., Sommaruga, Ruben, Steiner, Sara E., Verburg, Piet, Wain, Danielle, Weyhenmeyer, Gesa A., and Carey, Cayelan C.

Abstract

Declining oxygen concentrations in the deep waters of lakes worldwide pose a pressing environmental and societal challenge. Existing theory suggests that low deep-water dissolved oxygen (DO) concentrations could trigger a positive feedback through which anoxia (i.e., very low DO) during a given summer begets increasingly severe occurrences of anoxia in following summers. Specifically, anoxic conditions can promote nutrient release from sediments, thereby stimulating phytoplankton growth, and subsequent phytoplankton decomposition can fuel heterotrophic respiration, resulting in increased spatial extent and duration of anoxia. However, while the individual relationships in this feedback are well established, to our knowledge, there has not been a systematic analysis within or across lakes that simultaneously demonstrates all of the mechanisms necessary to produce a positive feedback that reinforces anoxia. Here, we compiled data from 656 widespread temperate lakes and reservoirs to analyze the proposed anoxia begets anoxia feedback. Lakes in the dataset span a broad range of surface area (1–126,909 ha), maximum depth (6–370 m), and morphometry, with a median time-series duration of 30 years at each lake. Using linear mixed models, we found support for each of the positive feedback relationships between anoxia, phosphorus concentrations, chlorophyll a concentrations, and oxygen demand across the 656-lake dataset. Likewise, we found further support for these relationships by analyzing time-series data from individual lakes. Our results indicate that the strength of these feedback relationships may vary with lake-specific characteristics: For example, we found that surface phosphorus concentrations were more positively associated with chlorophyll a in high-phosphorus lakes, and oxygen demand had a stronger influence on the extent of anoxia in deep lakes. Taken together, these results support the existence of a positive feedback that could magnify the effects of climate

Published
2024

2. Anoxia begets anoxia : A positive feedback to the deoxygenation of temperate lakes

Author

Lewis, Abigail S. L., Lau, Maximilian P., Jane, Stephen F., Rose, Kevin C., Be'eri-Shlevin, Yaron, Burnet, Sarah H., Clayer, François, Feuchtmayr, Heidrun, Grossart, Hans-Peter, Howard, Dexter W., Mariash, Heather, Delgado Martin, Jordi, North, Rebecca L., Oleksy, Isabella, Pilla, Rachel M., Smagula, Amy P., Sommaruga, Ruben, Steiner, Sara E., Verburg, Piet, Wain, Danielle, Weyhenmeyer, Gesa A., Carey, Cayelan C., Lewis, Abigail S. L., Lau, Maximilian P., Jane, Stephen F., Rose, Kevin C., Be'eri-Shlevin, Yaron, Burnet, Sarah H., Clayer, François, Feuchtmayr, Heidrun, Grossart, Hans-Peter, Howard, Dexter W., Mariash, Heather, Delgado Martin, Jordi, North, Rebecca L., Oleksy, Isabella, Pilla, Rachel M., Smagula, Amy P., Sommaruga, Ruben, Steiner, Sara E., Verburg, Piet, Wain, Danielle, Weyhenmeyer, Gesa A., and Carey, Cayelan C.

Abstract

Declining oxygen concentrations in the deep waters of lakes worldwide pose a pressing environmental and societal challenge. Existing theory suggests that low deep-water dissolved oxygen (DO) concentrations could trigger a positive feedback through which anoxia (i.e., very low DO) during a given summer begets increasingly severe occurrences of anoxia in following summers. Specifically, anoxic conditions can promote nutrient release from sediments, thereby stimulating phytoplankton growth, and subsequent phytoplankton decomposition can fuel heterotrophic respiration, resulting in increased spatial extent and duration of anoxia. However, while the individual relationships in this feedback are well established, to our knowledge, there has not been a systematic analysis within or across lakes that simultaneously demonstrates all of the mechanisms necessary to produce a positive feedback that reinforces anoxia. Here, we compiled data from 656 widespread temperate lakes and reservoirs to analyze the proposed anoxia begets anoxia feedback. Lakes in the dataset span a broad range of surface area (1–126,909 ha), maximum depth (6–370 m), and morphometry, with a median time-series duration of 30 years at each lake. Using linear mixed models, we found support for each of the positive feedback relationships between anoxia, phosphorus concentrations, chlorophyll a concentrations, and oxygen demand across the 656-lake dataset. Likewise, we found further support for these relationships by analyzing time-series data from individual lakes. Our results indicate that the strength of these feedback relationships may vary with lake-specific characteristics: For example, we found that surface phosphorus concentrations were more positively associated with chlorophyll a in high-phosphorus lakes, and oxygen demand had a stronger influence on the extent of anoxia in deep lakes. Taken together, these results support the existence of a positive feedback that could magnify the effects of climate

Published
2024
Full Text
View/download PDF

3. Anoxia begets anoxia: A positive feedback to the deoxygenation of temperate lakes

Author

Lewis, Abigail S. L., primary, Lau, Maximilian P., additional, Jane, Stephen F., additional, Rose, Kevin C., additional, Be'eri‐Shlevin, Yaron, additional, Burnet, Sarah H., additional, Clayer, François, additional, Feuchtmayr, Heidrun, additional, Grossart, Hans‐Peter, additional, Howard, Dexter W., additional, Mariash, Heather, additional, Delgado Martin, Jordi, additional, North, Rebecca L., additional, Oleksy, Isabella, additional, Pilla, Rachel M., additional, Smagula, Amy P., additional, Sommaruga, Ruben, additional, Steiner, Sara E., additional, Verburg, Piet, additional, Wain, Danielle, additional, Weyhenmeyer, Gesa A., additional, and Carey, Cayelan C., additional

Published
2023
Full Text
View/download PDF

6. Anoxia begets anoxia: A positive feedback to the deoxygenation of temperate lakes

Author

Lewis, Abigail S. L., Lau, Maximilian P., Jane, Stephen F., Rose, Kevin C., Be'eri-Shlevin, Yaron, Burnet, Sarah H., Clayer, François, Feuchtmayr, Heidrun, Grossart, Hans-Peter, Howard, Dexter W., Mariash, Heather, Delgado Martin, Jordi, North, Rebecca L., Oleksy, Isabella, Pilla, Rachel M., Smagula, Amy P., Sommaruga, Ruben, Steiner, Sara E., Verburg, Piet, Wain, Danielle, Weyhenmeyer, Gesa A., Carey, Cayelan C., Lewis, Abigail S. L., Lau, Maximilian P., Jane, Stephen F., Rose, Kevin C., Be'eri-Shlevin, Yaron, Burnet, Sarah H., Clayer, François, Feuchtmayr, Heidrun, Grossart, Hans-Peter, Howard, Dexter W., Mariash, Heather, Delgado Martin, Jordi, North, Rebecca L., Oleksy, Isabella, Pilla, Rachel M., Smagula, Amy P., Sommaruga, Ruben, Steiner, Sara E., Verburg, Piet, Wain, Danielle, Weyhenmeyer, Gesa A., and Carey, Cayelan C.

Abstract

Declining oxygen concentrations in the deep waters of lakes worldwide pose a pressing environmental and societal challenge. Existing theory suggests that low deep-water dissolved oxygen (DO) concentrations could trigger a positive feedback through which anoxia (i.e., very low DO) during a given summer begets increasingly severe occurrences of anoxia in following summers. Specifically, anoxic conditions can promote nutrient release from sediments, thereby stimulating phytoplankton growth, and subsequent phytoplankton decomposition can fuel heterotrophic respiration, resulting in increased spatial extent and duration of anoxia. However, while the individual relationships in this feedback are well established, to our knowledge, there has not been a systematic analysis within or across lakes that simultaneously demonstrates all of the mechanisms necessary to produce a positive feedback that reinforces anoxia. Here, we compiled data from 656 widespread temperate lakes and reservoirs to analyze the proposed anoxia begets anoxia feedback. Lakes in the dataset span a broad range of surface area (1–126,909 ha), maximum depth (6–370 m), and morphometry, with a median time-series duration of 30 years at each lake. Using linear mixed models, we found support for each of the positive feedback relationships between anoxia, phosphorus concentrations, chlorophyll a concentrations, and oxygen demand across the 656-lake dataset. Likewise, we found further support for these relationships by analyzing time-series data from individual lakes. Our results indicate that the strength of these feedback relationships may vary with lake-specific characteristics: For example, we found that surface phosphorus concentrations were more positively associated with chlorophyll a in high-phosphorus lakes, and oxygen demand had a stronger influence on the extent of anoxia in deep lakes. Taken together, these results support the existence of a positive feedback that could magnify the effects of climate

Published
2023

7. Changing Arctic snow cover: A review of recent developments and assessment of future needs for observations, modelling, and impacts

Author

Bokhorst, Stef, Pedersen, Stine Højlund, Brucker, Ludovic, Anisimov, Oleg, Bjerke, Jarle W., Brown, Ross D., Ehrich, Dorothee, Essery, Richard L. H., Heilig, Achim, Ingvander, Susanne, Johansson, Cecilia, Johansson, Margareta, Jónsdóttir, Ingibjörg Svala, Inga, Niila, Luojus, Kari, Macelloni, Giovanni, Mariash, Heather, McLennan, Donald, Rosqvist, Gunhild Ninis, Sato, Atsushi, Savela, Hannele, Schneebeli, Martin, Sokolov, Aleksandr, Sokratov, Sergey A., Terzago, Silvia, Vikhamar-Schuler, Dagrun, Williamson, Scott, Qiu, Yubao, and Callaghan, Terry V.

Published
2016

11. First circumpolar assessment of Arctic freshwater phytoplankton and zooplankton diversity: Spatial patterns and environmental factors

Author

Schartau, Ann Kristin, primary, Mariash, Heather L., additional, Christoffersen, Kirsten S., additional, Bogan, Daniel, additional, Dubovskaya, Olga P., additional, Fefilova, Elena B., additional, Hayden, Brian, additional, Ingvason, Haraldur R., additional, Ivanova, Elena A., additional, Kononova, Olga N., additional, Kravchuk, Elena S., additional, Lento, Jennifer, additional, Majaneva, Markus, additional, Novichkova, Anna A., additional, Rautio, Milla, additional, R__hland, Kathleen M., additional, Shaftel, Rebecca, additional, Smol, John P., additional, Vrede, Tobias, additional, and Kahilainen, Kimmo K., additional

Published
2021
Full Text
View/download PDF

13. First circumpolar assessment of Arctic freshwater phytoplankton and zooplankton diversity: Spatial patterns and environmental factors.

Author

Schartau, Ann Kristin, Mariash, Heather L., Christoffersen, Kirsten S., Bogan, Daniel, Dubovskaya, Olga P., Fefilova, Elena B., Hayden, Brian, Ingvason, Haraldur R., Ivanova, Elena A., Kononova, Olga N., Kravchuk, Elena S., Lento, Jennifer, Majaneva, Markus, Novichkova, Anna A., Rautio, Milla, R__hland, Kathleen M., Shaftel, Rebecca, Smol, John P., Vrede, Tobias, and Kahilainen, Kimmo K.

Subjects
*FRESHWATER zooplankton, *FRESHWATER phytoplankton, *NUMBERS of species, *SPECIES pools, *SPECIES distribution, *ATMOSPHERIC temperature
Abstract

Arctic freshwaters are facing multiple environmental pressures, including rapid climate change and increasing land___use activities. Freshwater plankton assemblages are expected to reflect the effects of these stressors through shifts in species distributions and changes to biodiversity. These changes may occur rapidly due to the short generation times and high dispersal capabilities of both phyto___ and zooplankton.Spatial patterns and contemporary trends in plankton diversity throughout the circumpolar region were assessed using data from more than 300 lakes in the U.S.A. (Alaska), Canada, Greenland, Iceland, the Faroe Islands, Norway, Sweden, Finland, and Russia. The main objectives of this study were: (1) to assess spatial patterns of plankton diversity focusing on pelagic communities; (2) to assess dominant component of __ diversity (turnover or nestedness); (3) to identify which environmental factors best explain diversity; and (4) to provide recommendations for future monitoring and assessment of freshwater plankton communities across the Arctic region.Phytoplankton and crustacean zooplankton diversity varied substantially across the Arctic and was positively related to summer air temperature. However, for zooplankton, the positive correlation between summer temperature and species numbers decreased with increasing latitude. Taxonomic richness was lower in the high Arctic compared to the sub___ and low Arctic for zooplankton but this pattern was less clear for phytoplankton. Fennoscandia and inland regions of Russia represented hotspots for, respectively, phytoplankton and zooplankton diversity, whereas isolated regions had lower taxonomic richness. Ecoregions with high __ diversity generally also had high __ diversity, and turnover was the most important component of __ diversity in all ecoregions.For both phytoplankton and zooplankton, climatic variables were the most important environmental factors influencing diversity patterns, consistent with previous studies that examined shorter temperature gradients. However, barriers to dispersal may have also played a role in limiting diversity on islands. A better understanding of how diversity patterns are determined by colonisation history, environmental variables, and biotic interactions requires more monitoring data with locations dispersed evenly across the circumpolar Arctic. Furthermore, the importance of turnover in regional diversity patterns indicates that more extensive sampling is required to fully characterise the species pool of Arctic lakes. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

14. State of the Arctic Freshwater Biodiversity : report

Author

Lento, Jennifer, Goedkoop, Willem, Culp, Joseph, Christoffersen, Kirsten, Fefilova, Elena, Guðbergsson, Guðni, Fannar Lárusson, Kári, Liljaniemi, Petri, Ólafsson, Jón S., Sandøy, Steinar, Zimmerman, Christian, Christensen, Tom, Chambers, Patricia, Heino, Jani, Hellsten, Seppo, Kahlert, Maria, Keck, Francois, Laske, Sarah, Chun Pong Lau, Danny, Lavoie, Isabelle, Levenstein, Brianna, Mariash, Heather, Rühland, Kathleen, Saulnier-Talbot, Emilie, Schartau, Ann Kristin, and Svenning, Martin

Subjects
Ecology
Published
2019

15. A decade of shaping the futures of polar early career researchers: A legacy of the International Polar Year

Author

Hindshaw, Ruth S., Mariash, Heather, Vick-Majors, Trista J., Thornton, Alexander E., Pope, Allen, Zaika, Yulia, Lenz, Josefine, Nielsen, Hanne, Fugmann, Gerlis, Hindshaw, Ruth S., Mariash, Heather, Vick-Majors, Trista J., Thornton, Alexander E., Pope, Allen, Zaika, Yulia, Lenz, Josefine, Nielsen, Hanne, and Fugmann, Gerlis

Abstract

The Association of Polar Early Career Scientists (APECS) is an important legacy of the International Polar Year (IPY). APECS continues to foster engagement in education, outreach and communication (EOC) activities relating to the polar regions and provide training for early career researchers (ECRs). We highlight opportunities for training, leadership and skills development, such as the annual Polar Weeks and Antarctica Day celebrations. Participation and engagement in EOC activities actively contributes to career development by enabling ECRs to develop valuable soft skills such as networking, communication and interdisciplinary knowledge. A pilot survey on EOC engagement highlighted that those who organise events also gain leadership skills such as team management. We discuss several factors contributing to the success of APECS in training the next generation of polar leaders. These include the geographical rather than discipline-specific focus of the organisation, utilisation of online resources, including social media, and the strong links with partner organisations. These examples demonstrate how the EOC legacy of IPY has continued due to APECS’ targeted efforts to create EOC opportunities and provide skills and leadership training for ECRs.

Published
2019

20. Ecology under lake ice

Author

Hampton, Stephanie E., Galloway, Aaron W. E., Powers, Stephen M., Ozersky, Ted, Woo, Kara H., Batt, Ryan D., Labou, Stephanie G., O'Reilly, Catherine M., Sharma, Sapna, Lottig, Noah R., Stanley, Emily H., North, Rebecca L., Stockwell, Jason D., Adrian, Rita, Weyhenmeyer, Gesa A., Arvola, Lauri, Baulch, Helen M., Bertani, Isabella, Bowman, Larry L., Jr., Carey, Cayelan C., Catalan, Jordi, Colom-Montero, William, Domine, Leah M., Felip, Marisol, Granados, Ignacio, Gries, Corinna, Grossart, Hans-Peter, Haberman, Juta, Haldna, Marina, Hayden, Brian, Higgins, Scott N., Jolley, Jeff C., Kahilainen, Kimmo K., Kaup, Enn, Kehoe, Michael J., MacIntyre, Sally, Mackay, Anson W., Mariash, Heather L., Mckay, Robert M., Nixdorf, Brigitte, Noges, Peeter, Noges, Tiina, Palmer, Michelle, Pierson, Don C., Post, David M., Pruett, Matthew J., Rautio, Milla, Read, Jordan S., Roberts, Sarah L., Ruecker, Jacqueline, Sadro, Steven, Silow, Eugene A., Smith, Derek E., Sterner, Robert W., Swann, George E. A., Timofeyev, Maxim A., Toro, Manuel, Twiss, Michael R., Vogt, Richard J., Watson, Susan B., Whiteford, Erika J., Xenopoulos, Marguerite A., Coastal dynamics, Fluvial systems and Global change, Palaeo-ecologie, Biological Sciences, Lammi Biological Station, Environmental Sciences, Coastal dynamics, Fluvial systems and Global change, and Palaeo-ecologie

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, data synthesis, Limnology, AULACOSEIRA-BAICALENSIS, Aquatic ecosystem, 01 natural sciences, Zooplankton, Phytoplankton, Temperate climate, Ecosystem, Ice Cover, freshwater, lake, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, Abiotic component, Ekologi, long-term, CLIMATE-CHANGE, SEASONAL SUCCESSION, Ecology, 010604 marine biology & hydrobiology, limnology, plankton, NORTH-ATLANTIC OSCILLATION, UNDER-ICE, Plankton, seasonal, Snow, WINTER LIMNOLOGY, PLANKTON SUCCESSION, Lakes, 13. Climate action, FRESH-WATER LAKES, COVERED LAKES, 1181 Ecology, evolutionary biology, Environmental science, Seasons, long‐term, time series, 500 Naturwissenschaften und Mathematik::570 Biowissenschaften, Biologie::577 Ökologie, COMMUNITY STRUCTURE, winter ecology
Abstract

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass. National Science Foundation (NSF DEB) [1431428, 1136637]; Washington State University; Russian Science Foundation [14-14-00400]; Ministry of education and science of Russia Gos-Zasanie project [1354-2014/51]; Natural Environment Research Council [NE/J00829X/1, 1230750, NE/G019622/1, NE/J010227/1] Funding was provided by the National Science Foundation (NSF DEB #1431428; NSF DEB #1136637) and Washington State University. M. Timofeyev and E. Silow were partially supported by Russian Science Foundation project No 14-14-00400 and Ministry of education and science of Russia Gos-Zasanie project No 1354-2014/51. We are grateful to Marianne Moore, Deniz Ozkundakci, Chris Polashenski and Paula Kankaala for discussions that greatly improved this work. We also gratefully acknowledge the following individuals for contributing to this project: John Anderson, Jill Baron, Rick Bourbonniere, Sandra Brovold, Lluis Camarero, Sudeep Chandra, Jim Cotner, Laura Forsstom, Guillaume Grosbois, Chris Harrod, Klaus D. Joehnk, T.Y. Kim, Daniel Langenhaun, Reet Laugaste, Suzanne McGowan, Virginia Panizzo, Giampaolo Rossetti, R.E.H. Smith, Sarah Spaulding, Helen Tammert, Steve Thackeray, Kyle Zimmer, Priit Zingel and two anonymous reviewers. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

Published
2017

23. Ecology under lake ice

Author

Coastal dynamics, Fluvial systems and Global change, Palaeo-ecologie, Hampton, Stephanie E., Galloway, Aaron W. E., Powers, Stephen M., Ozersky, Ted, Woo, Kara H., Batt, Ryan D., Labou, Stephanie G., O'Reilly, Catherine M., Sharma, Sapna, Lottig, Noah R., Stanley, Emily H., North, Rebecca L., Stockwell, Jason D., Adrian, Rita, Weyhenmeyer, Gesa A., Arvola, Lauri, Baulch, Helen M., Bertani, Isabella, Bowman, Larry L., Jr., Carey, Cayelan C., Catalan, Jordi, Colom-Montero, William, Domine, Leah M., Felip, Marisol, Granados, Ignacio, Gries, Corinna, Grossart, Hans-Peter, Haberman, Juta, Haldna, Marina, Hayden, Brian, Higgins, Scott N., Jolley, Jeff C., Kahilainen, Kimmo K., Kaup, Enn, Kehoe, Michael J., MacIntyre, Sally, Mackay, Anson W., Mariash, Heather L., Mckay, Robert M., Nixdorf, Brigitte, Noges, Peeter, Noges, Tiina, Palmer, Michelle, Pierson, Don C., Post, David M., Pruett, Matthew J., Rautio, Milla, Read, Jordan S., Roberts, Sarah L., Ruecker, Jacqueline, Sadro, Steven, Silow, Eugene A., Smith, Derek E., Sterner, Robert W., Swann, George E. A., Timofeyev, Maxim A., Toro, Manuel, Twiss, Michael R., Vogt, Richard J., Watson, Susan B., Whiteford, Erika J., Xenopoulos, Marguerite A., Coastal dynamics, Fluvial systems and Global change, Palaeo-ecologie, Hampton, Stephanie E., Galloway, Aaron W. E., Powers, Stephen M., Ozersky, Ted, Woo, Kara H., Batt, Ryan D., Labou, Stephanie G., O'Reilly, Catherine M., Sharma, Sapna, Lottig, Noah R., Stanley, Emily H., North, Rebecca L., Stockwell, Jason D., Adrian, Rita, Weyhenmeyer, Gesa A., Arvola, Lauri, Baulch, Helen M., Bertani, Isabella, Bowman, Larry L., Jr., Carey, Cayelan C., Catalan, Jordi, Colom-Montero, William, Domine, Leah M., Felip, Marisol, Granados, Ignacio, Gries, Corinna, Grossart, Hans-Peter, Haberman, Juta, Haldna, Marina, Hayden, Brian, Higgins, Scott N., Jolley, Jeff C., Kahilainen, Kimmo K., Kaup, Enn, Kehoe, Michael J., MacIntyre, Sally, Mackay, Anson W., Mariash, Heather L., Mckay, Robert M., Nixdorf, Brigitte, Noges, Peeter, Noges, Tiina, Palmer, Michelle, Pierson, Don C., Post, David M., Pruett, Matthew J., Rautio, Milla, Read, Jordan S., Roberts, Sarah L., Ruecker, Jacqueline, Sadro, Steven, Silow, Eugene A., Smith, Derek E., Sterner, Robert W., Swann, George E. A., Timofeyev, Maxim A., Toro, Manuel, Twiss, Michael R., Vogt, Richard J., Watson, Susan B., Whiteford, Erika J., and Xenopoulos, Marguerite A.

Published
2017

25. Ecology under lake ice

Author

Biological Sciences, Hampton, Stephanie E., Galloway, Aaron W. E., Powers, Stephen M., Ozersky, Ted, Woo, Kara H., Batt, Ryan D., Labou, Stephanie G., O'Reilly, Catherine M., Sharma, Sapna, Lottig, Noah R., Stanley, Emily H., North, Rebecca L., Stockwell, Jason D., Adrian, Rita, Weyhenmeyer, Gesa A., Arvola, Lauri, Baulch, Helen M., Bertani, Isabella, Bowman, Larry L., Jr., Carey, Cayelan C., Catalan, Jordi, Colom-Montero, William, Domine, Leah M., Felip, Marisol, Granados, Ignacio, Gries, Corinna, Grossart, Hans-Peter, Haberman, Juta, Haldna, Marina, Hayden, Brian, Higgins, Scott N., Jolley, Jeff C., Kahilainen, Kimmo K., Kaup, Enn, Kehoe, Michael J., MacIntyre, Sally, Mackay, Anson W., Mariash, Heather L., McKay, Robert M., Nixdorf, Brigitte, Noges, Peeter, Noges, Tiina, Palmer, Michelle, Pierson, Don C., Post, David M., Pruett, Matthew J., Rautio, Milla, Read, Jordan S., Roberts, Sarah L., Ruecker, Jacqueline, Sadro, Steven, Silow, Eugene A., Smith, Derek E., Sterner, Robert W., Swann, George E. A., Timofeyev, Maxim A., Toro, Manuel, Twiss, Michael R., Vogt, Richard J., Watson, Susan B., Whiteford, Erika J., Xenopoulos, Marguerite A., Biological Sciences, Hampton, Stephanie E., Galloway, Aaron W. E., Powers, Stephen M., Ozersky, Ted, Woo, Kara H., Batt, Ryan D., Labou, Stephanie G., O'Reilly, Catherine M., Sharma, Sapna, Lottig, Noah R., Stanley, Emily H., North, Rebecca L., Stockwell, Jason D., Adrian, Rita, Weyhenmeyer, Gesa A., Arvola, Lauri, Baulch, Helen M., Bertani, Isabella, Bowman, Larry L., Jr., Carey, Cayelan C., Catalan, Jordi, Colom-Montero, William, Domine, Leah M., Felip, Marisol, Granados, Ignacio, Gries, Corinna, Grossart, Hans-Peter, Haberman, Juta, Haldna, Marina, Hayden, Brian, Higgins, Scott N., Jolley, Jeff C., Kahilainen, Kimmo K., Kaup, Enn, Kehoe, Michael J., MacIntyre, Sally, Mackay, Anson W., Mariash, Heather L., McKay, Robert M., Nixdorf, Brigitte, Noges, Peeter, Noges, Tiina, Palmer, Michelle, Pierson, Don C., Post, David M., Pruett, Matthew J., Rautio, Milla, Read, Jordan S., Roberts, Sarah L., Ruecker, Jacqueline, Sadro, Steven, Silow, Eugene A., Smith, Derek E., Sterner, Robert W., Swann, George E. A., Timofeyev, Maxim A., Toro, Manuel, Twiss, Michael R., Vogt, Richard J., Watson, Susan B., Whiteford, Erika J., and Xenopoulos, Marguerite A.

Abstract

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass.

Published
2017

26. Fall Composition of Storage Lipids is Associated with the Overwintering Strategy of Daphnia

Author

Mariash, Heather L., Cusson, Mathieu, Rautio, Milla, Coastal dynamics, Fluvial systems and Global change, and Coastal dynamics, Fluvial systems and Global change

Subjects
0106 biological sciences, SDA, Zoology, Diapause, 010603 evolutionary biology, 01 natural sciences, Daphnia, Zooplankton, Biochemistry, Life history strategies, chemistry.chemical_compound, Freshwater, Animals, Fatty acids, Overwintering, reproductive and urinary physiology, Trophic level, biology, Ecology, 010604 marine biology & hydrobiology, Seston, fungi, Ice, Winter, Organic Chemistry, Fatty Acids, Cell Biology, Feeding Behavior, biology.organism_classification, Subarctic climate, chemistry, Adipose Tissue, Seasons, Stearidonic acid
Abstract

Diapause, which occurs through the production of dormant eggs, is a strategy used by some zooplankton to avoid winter months of persistent low temperatures and low food availability. However, reports of active zooplankton under the ice indicate that other strategies also exist. This study was aimed at evaluating whether the composition of storage lipids in the fall differs between diapausing and active overwintering Daphnia. We assessed the quantity of storage lipids and fatty acid (FA) composition of Daphnia species, along with FA content of seston, in six boreal, alpine and subarctic lakes at the onset of winter, and evaluated the association between storage lipids and Daphnia overwintering strategy. We found that active overwintering Daphnia had >55% body fat and the highest FA concentrations. Polyunsaturated FA, especially stearidonic acid (18:4n-3; SDA) and high ratios of n-3:n-6, were preferentially retained to a greater extent in active overwintering Daphnia than in those that entered diapause. Daphnia FA composition was independent of that of the seston diet, indicating that Daphnia adjusted their storage lipids according to the physiological requirements of a given overwintering strategy. The occurrence of an active overwintering strategy has consequences for zooplankton community structure, and can have important implications for the transfer of high-quality energy at higher trophic levels.

Published
2016

28. Experimental tests of phytoplankton response to ornithological eutrophication in Arctic freshwaters.

Author

Mariash, Heather L., Rauito, Milla, Mallory, Mark, and Smith, Paul A.

Subjects
MICROCYSTIS, SNOW goose, PHOSPHORUS in water, EUTROPHICATION, NITROGEN in water, WATER chemistry
Abstract

Many populations of Arctic-breeding geese have increased in abundance in recent decades, and in the Canadian Arctic, Snow (Chen caerulescens) and Ross' Geese (Chen rossii) are formally considered overabundant by wildlife managers. The impacts of these overabundant geese on terrestrial habitats are well documented, and more recently, studies have suggested impacts to freshwater ecosystems as well. The direct contribution of nutrients from goose faeces to water chemistry could have cascading effects on biological functioning, through changes in phytoplankton productivity and community composition. We demonstrated previously that goose faeces can enrich ponds with nutrients at a landscape scale. Here, we show experimentally that goose droppings rapidly released nitrogen and phosphorus when submerged in freshwater, increasing the dissolved nitrogen and phosphorus in the water. This resulted in both a decrease in the nitrogen:phosphorus ratio and an increase in cyanobacteria in the goose dropping treatment. In contrast, this pattern was not found when we submerged cut sedge (Carex sp.) leaves. These results demonstrate that geese act as biovectors, causing terrestrial nutrients to be bioavailable in freshwater systems. Collectively, the results demonstrate the direct ecological consequences of ornithological nutrient loading from hyperabundant geese in Arctic freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

29. Changing Arctic snow cover: A review of recent developments and assessment of future needs for observations, modelling, and impacts

Author

Palaeo-ecologie, Coastal dynamics, Fluvial systems and Global change, Bokhorst, Stef, Pedersen, Stine Højlund, Brucker, Ludovic, Anisimov, Oleg, Bjerke, Jarle W., Brown, Ross D., Ehrich, Dorothee, Essery, Richard L. H., Heilig, Achim, Ingvander, Susanne, Johansson, Cecilia, Johansson, Margareta, Jónsdóttir, Ingibjörg Svala, Inga, Niila, Luojus, Kari, Macelloni, Giovanni, Mariash, Heather, Mclennan, Donald, Rosqvist, Gunhild Ninis, Sato, Atsushi, Savela, Hannele, Schneebeli, Martin, Sokolov, Aleksandr, Sokratov, Sergey A., Terzago, Silvia, Vikhamar-schuler, Dagrun, Williamson, Scott, Qiu, Yubao, Callaghan, Terry V., Palaeo-ecologie, Coastal dynamics, Fluvial systems and Global change, Bokhorst, Stef, Pedersen, Stine Højlund, Brucker, Ludovic, Anisimov, Oleg, Bjerke, Jarle W., Brown, Ross D., Ehrich, Dorothee, Essery, Richard L. H., Heilig, Achim, Ingvander, Susanne, Johansson, Cecilia, Johansson, Margareta, Jónsdóttir, Ingibjörg Svala, Inga, Niila, Luojus, Kari, Macelloni, Giovanni, Mariash, Heather, Mclennan, Donald, Rosqvist, Gunhild Ninis, Sato, Atsushi, Savela, Hannele, Schneebeli, Martin, Sokolov, Aleksandr, Sokratov, Sergey A., Terzago, Silvia, Vikhamar-schuler, Dagrun, Williamson, Scott, Qiu, Yubao, and Callaghan, Terry V.

Published
2016

30. Benthic mats offer a potential subsidy to pelagic consumers in tundra pond food webs

Author

Mariash, Heather, Devlin, Shawn, Forsström, Laura, Jones, Roger, and Rautio, Milla

Subjects
tundra ponds, nutrition contrubution, pelagic consumers, benthic mats
Abstract

We quantified the potential nutritional contribution of benthic mats to pelagic consumers in tundra ponds using three approaches. (1) We compared benthic and pelagic habitats based on their algal biomass and community composition and assessed the dietary quality in terms of fatty acid (FA) concentrations in both habitats. The algal community compositions differed significantly between habitats. Both benthic and pelagic habitats contained saturated and unsaturated FAs, but on average there were more FAs relative to carbon in the pelagic habitat (44 6 29 mg mg C21) than the benthic habitat (23 6 18 mg mg C21) across all studied ponds. (2) We quantified the contribution of benthic mats to the whole-lake FA pool and found that benthic mats dominate (on average . 90%) the basal FA resource within tundra ponds. (3) Using a series of feeding experiments, we found that Daphnia survival and FA concentrations increased when a benthic mat slurry supplemented low concentrations of phytoplankton. However, Daphnia could not survive solely on benthic mats, and nor did benthic mats increase adult Daphnia survival when mats were offered as coherent pieces. The extent to which pelagic consumers could be supported by benthic production challenges the view that benthic habitats are functionally separate from the pelagic food webs within northern lake ecosystems. peerReviewed

Published
2014

31. Ecology under lake ice

Author

Hampton, Stephanie E., primary, Galloway, Aaron W. E., additional, Powers, Stephen M., additional, Ozersky, Ted, additional, Woo, Kara H., additional, Batt, Ryan D., additional, Labou, Stephanie G., additional, O'Reilly, Catherine M., additional, Sharma, Sapna, additional, Lottig, Noah R., additional, Stanley, Emily H., additional, North, Rebecca L., additional, Stockwell, Jason D., additional, Adrian, Rita, additional, Weyhenmeyer, Gesa A., additional, Arvola, Lauri, additional, Baulch, Helen M., additional, Bertani, Isabella, additional, Bowman, Larry L., additional, Carey, Cayelan C., additional, Catalan, Jordi, additional, Colom‐Montero, William, additional, Domine, Leah M., additional, Felip, Marisol, additional, Granados, Ignacio, additional, Gries, Corinna, additional, Grossart, Hans‐Peter, additional, Haberman, Juta, additional, Haldna, Marina, additional, Hayden, Brian, additional, Higgins, Scott N., additional, Jolley, Jeff C., additional, Kahilainen, Kimmo K., additional, Kaup, Enn, additional, Kehoe, Michael J., additional, MacIntyre, Sally, additional, Mackay, Anson W., additional, Mariash, Heather L., additional, McKay, Robert M., additional, Nixdorf, Brigitte, additional, Nõges, Peeter, additional, Nõges, Tiina, additional, Palmer, Michelle, additional, Pierson, Don C., additional, Post, David M., additional, Pruett, Matthew J., additional, Rautio, Milla, additional, Read, Jordan S., additional, Roberts, Sarah L., additional, Rücker, Jacqueline, additional, Sadro, Steven, additional, Silow, Eugene A., additional, Smith, Derek E., additional, Sterner, Robert W., additional, Swann, George E. A., additional, Timofeyev, Maxim A., additional, Toro, Manuel, additional, Twiss, Michael R., additional, Vogt, Richard J., additional, Watson, Susan B., additional, Whiteford, Erika J., additional, and Xenopoulos, Marguerite A., additional

Published
2016
Full Text
View/download PDF

32. Seasonal feeding strategies of subarctic zooplankton

Author

Mariash, Heather

Subjects
parthenogenetics, DNA-analyysi, suvullinen lisääntyminen, pussikehrääjät, perhoset, genetic diversity, lisääntyminen, barcoding, geneettinen muuntelu, morfologia, loiset, sex, suvuton lisääntyminen, polyploidy
Published
2012

37. Anoxia begets anoxia: A positive feedback to the deoxygenation of temperate lakes.

Author

Lewis ASL, Lau MP, Jane SF, Rose KC, Be'eri-Shlevin Y, Burnet SH, Clayer F, Feuchtmayr H, Grossart HP, Howard DW, Mariash H, Delgado Martin J, North RL, Oleksy I, Pilla RM, Smagula AP, Sommaruga R, Steiner SE, Verburg P, Wain D, Weyhenmeyer GA, and Carey CC

Subjects
Humans, Chlorophyll A analysis, Feedback, Hypoxia, Phosphorus analysis, Oxygen, Eutrophication, Lakes, Environmental Monitoring methods
Abstract

Declining oxygen concentrations in the deep waters of lakes worldwide pose a pressing environmental and societal challenge. Existing theory suggests that low deep-water dissolved oxygen (DO) concentrations could trigger a positive feedback through which anoxia (i.e., very low DO) during a given summer begets increasingly severe occurrences of anoxia in following summers. Specifically, anoxic conditions can promote nutrient release from sediments, thereby stimulating phytoplankton growth, and subsequent phytoplankton decomposition can fuel heterotrophic respiration, resulting in increased spatial extent and duration of anoxia. However, while the individual relationships in this feedback are well established, to our knowledge, there has not been a systematic analysis within or across lakes that simultaneously demonstrates all of the mechanisms necessary to produce a positive feedback that reinforces anoxia. Here, we compiled data from 656 widespread temperate lakes and reservoirs to analyze the proposed anoxia begets anoxia feedback. Lakes in the dataset span a broad range of surface area (1-126,909 ha), maximum depth (6-370 m), and morphometry, with a median time-series duration of 30 years at each lake. Using linear mixed models, we found support for each of the positive feedback relationships between anoxia, phosphorus concentrations, chlorophyll a concentrations, and oxygen demand across the 656-lake dataset. Likewise, we found further support for these relationships by analyzing time-series data from individual lakes. Our results indicate that the strength of these feedback relationships may vary with lake-specific characteristics: For example, we found that surface phosphorus concentrations were more positively associated with chlorophyll a in high-phosphorus lakes, and oxygen demand had a stronger influence on the extent of anoxia in deep lakes. Taken together, these results support the existence of a positive feedback that could magnify the effects of climate change and other anthropogenic pressures driving the development of anoxia in lakes around the world., (© 2023 Oak Ridge National Laboratory and The Authors. Global Change Biology published by John Wiley & Sons Ltd. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Published
2024
Full Text
View/download PDF

38. Ecology under lake ice.

Author

Hampton SE, Galloway AW, Powers SM, Ozersky T, Woo KH, Batt RD, Labou SG, O'Reilly CM, Sharma S, Lottig NR, Stanley EH, North RL, Stockwell JD, Adrian R, Weyhenmeyer GA, Arvola L, Baulch HM, Bertani I, Bowman LL Jr, Carey CC, Catalan J, Colom-Montero W, Domine LM, Felip M, Granados I, Gries C, Grossart HP, Haberman J, Haldna M, Hayden B, Higgins SN, Jolley JC, Kahilainen KK, Kaup E, Kehoe MJ, MacIntyre S, Mackay AW, Mariash HL, McKay RM, Nixdorf B, Nõges P, Nõges T, Palmer M, Pierson DC, Post DM, Pruett MJ, Rautio M, Read JS, Roberts SL, Rücker J, Sadro S, Silow EA, Smith DE, Sterner RW, Swann GE, Timofeyev MA, Toro M, Twiss MR, Vogt RJ, Watson SB, Whiteford EJ, and Xenopoulos MA

Subjects
Seasons, Ecosystem, Ice Cover, Lakes, Plankton physiology
Abstract

Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including 36 abiotic and biotic variables from 42 research groups and 101 lakes, examining seasonal differences and connections as well as how seasonal differences vary with geophysical factors. Plankton were more abundant under ice than expected; mean winter values were 43.2% of summer values for chlorophyll a, 15.8% of summer phytoplankton biovolume and 25.3% of summer zooplankton density. Dissolved nitrogen concentrations were typically higher during winter, and these differences were exaggerated in smaller lakes. Lake size also influenced winter-summer patterns for dissolved organic carbon (DOC), with higher winter DOC in smaller lakes. At coarse levels of taxonomic aggregation, phytoplankton and zooplankton community composition showed few systematic differences between seasons, although literature suggests that seasonal differences are frequently lake-specific, species-specific, or occur at the level of functional group. Within the subset of lakes that had longer time series, winter influenced the subsequent summer for some nutrient variables and zooplankton biomass., (© 2016 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd.)

Published
2017
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results