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Publisher: Springer-Verlag (Total: 2351 journals)

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Showing 1 - 200 of 2351 Journals sorted alphabetically
3D Printing in Medicine     Open Access   (Followers: 2)
3D Research     Hybrid Journal   (Followers: 21, SJR: 0.222, CiteScore: 1)
4OR: A Quarterly J. of Operations Research     Hybrid Journal   (Followers: 10, SJR: 0.825, CiteScore: 1)
AAPS J.     Hybrid Journal   (Followers: 25, SJR: 1.118, CiteScore: 4)
AAPS PharmSciTech     Hybrid Journal   (Followers: 7, SJR: 0.752, CiteScore: 3)
Abdominal Radiology     Hybrid Journal   (Followers: 17, SJR: 0.866, CiteScore: 2)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 4, SJR: 0.439, CiteScore: 0)
Academic Psychiatry     Full-text available via subscription   (Followers: 29, SJR: 0.53, CiteScore: 1)
Academic Questions     Hybrid Journal   (Followers: 8, SJR: 0.106, CiteScore: 0)
Accreditation and Quality Assurance: J. for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 31, SJR: 0.316, CiteScore: 1)
Acoustical Physics     Hybrid Journal   (Followers: 11, SJR: 0.359, CiteScore: 1)
Acoustics Australia     Hybrid Journal   (SJR: 0.232, CiteScore: 1)
Acta Analytica     Hybrid Journal   (Followers: 7, SJR: 0.367, CiteScore: 0)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1, SJR: 0.675, CiteScore: 1)
Acta Biotheoretica     Hybrid Journal   (Followers: 4, SJR: 0.284, CiteScore: 1)
Acta Diabetologica     Hybrid Journal   (Followers: 19, SJR: 1.587, CiteScore: 3)
Acta Endoscopica     Hybrid Journal   (Followers: 1)
acta ethologica     Hybrid Journal   (Followers: 4, SJR: 0.769, CiteScore: 1)
Acta Geochimica     Hybrid Journal   (Followers: 7, SJR: 0.24, CiteScore: 1)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 3, SJR: 0.305, CiteScore: 1)
Acta Geophysica     Hybrid Journal   (Followers: 11, SJR: 0.312, CiteScore: 1)
Acta Geotechnica     Hybrid Journal   (Followers: 7, SJR: 1.588, CiteScore: 3)
Acta Informatica     Hybrid Journal   (Followers: 5, SJR: 0.517, CiteScore: 1)
Acta Mathematica     Hybrid Journal   (Followers: 13, SJR: 7.066, CiteScore: 3)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2, SJR: 0.452, CiteScore: 1)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 6, SJR: 0.379, CiteScore: 1)
Acta Mathematica Vietnamica     Hybrid Journal   (SJR: 0.27, CiteScore: 0)
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal   (SJR: 0.208, CiteScore: 0)
Acta Mechanica     Hybrid Journal   (Followers: 21, SJR: 1.04, CiteScore: 2)
Acta Mechanica Sinica     Hybrid Journal   (Followers: 5, SJR: 0.607, CiteScore: 2)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7, SJR: 0.576, CiteScore: 2)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.638, CiteScore: 1)
Acta Neurochirurgica     Hybrid Journal   (Followers: 7, SJR: 0.822, CiteScore: 2)
Acta Neurologica Belgica     Hybrid Journal   (Followers: 2, SJR: 0.376, CiteScore: 1)
Acta Neuropathologica     Hybrid Journal   (Followers: 4, SJR: 7.589, CiteScore: 12)
Acta Oceanologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.334, CiteScore: 1)
Acta Physiologiae Plantarum     Hybrid Journal   (Followers: 3, SJR: 0.574, CiteScore: 2)
Acta Politica     Hybrid Journal   (Followers: 19, SJR: 0.605, CiteScore: 1)
Activitas Nervosa Superior     Hybrid Journal   (SJR: 0.147, CiteScore: 0)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8, SJR: 0.103, CiteScore: 0)
ADHD Attention Deficit and Hyperactivity Disorders     Hybrid Journal   (Followers: 26, SJR: 0.72, CiteScore: 2)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Administration and Policy in Mental Health and Mental Health Services Research     Partially Free   (Followers: 18, SJR: 1.005, CiteScore: 2)
Adsorption     Hybrid Journal   (Followers: 5, SJR: 0.703, CiteScore: 2)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 4, SJR: 0.698, CiteScore: 1)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 37, SJR: 0.956, CiteScore: 2)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 20, SJR: 0.812, CiteScore: 1)
Advances in Contraception     Hybrid Journal   (Followers: 3)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 58, SJR: 1.09, CiteScore: 1)
Advances in Gerontology     Partially Free   (Followers: 8, SJR: 0.144, CiteScore: 0)
Advances in Health Sciences Education     Hybrid Journal   (Followers: 32, SJR: 1.64, CiteScore: 2)
Advances in Manufacturing     Hybrid Journal   (Followers: 3, SJR: 0.475, CiteScore: 2)
Advances in Polymer Science     Hybrid Journal   (Followers: 46, SJR: 1.04, CiteScore: 3)
Advances in Therapy     Hybrid Journal   (Followers: 5, SJR: 1.075, CiteScore: 3)
Aegean Review of the Law of the Sea and Maritime Law     Hybrid Journal   (Followers: 7)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2, SJR: 0.517, CiteScore: 1)
Aerobiologia     Hybrid Journal   (Followers: 3, SJR: 0.673, CiteScore: 2)
Aesthetic Plastic Surgery     Hybrid Journal   (Followers: 11, SJR: 0.825, CiteScore: 1)
African Archaeological Review     Hybrid Journal   (Followers: 21, SJR: 0.862, CiteScore: 1)
Afrika Matematika     Hybrid Journal   (Followers: 1, SJR: 0.235, CiteScore: 0)
AGE     Hybrid Journal   (Followers: 7)
Ageing Intl.     Hybrid Journal   (Followers: 7, SJR: 0.39, CiteScore: 1)
Aggiornamenti CIO     Hybrid Journal   (Followers: 1)
Aging Clinical and Experimental Research     Hybrid Journal   (Followers: 3, SJR: 0.67, CiteScore: 2)
Agricultural Research     Hybrid Journal   (Followers: 6, SJR: 0.276, CiteScore: 1)
Agriculture and Human Values     Open Access   (Followers: 14, SJR: 1.173, CiteScore: 3)
Agroforestry Systems     Open Access   (Followers: 20, SJR: 0.663, CiteScore: 1)
Agronomy for Sustainable Development     Open Access   (Followers: 15, SJR: 1.864, CiteScore: 6)
AI & Society     Hybrid Journal   (Followers: 9, SJR: 0.227, CiteScore: 1)
AIDS and Behavior     Hybrid Journal   (Followers: 14, SJR: 1.792, CiteScore: 3)
Air Quality, Atmosphere & Health     Hybrid Journal   (Followers: 4, SJR: 0.862, CiteScore: 3)
Akupunktur & Aurikulomedizin     Full-text available via subscription   (Followers: 1)
Algebra and Logic     Hybrid Journal   (Followers: 6, SJR: 0.531, CiteScore: 0)
Algebra Universalis     Hybrid Journal   (Followers: 2, SJR: 0.583, CiteScore: 1)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1, SJR: 1.095, CiteScore: 1)
Algorithmica     Hybrid Journal   (Followers: 9, SJR: 0.56, CiteScore: 1)
Allergo J.     Full-text available via subscription   (Followers: 1, SJR: 0.234, CiteScore: 0)
Allergo J. Intl.     Hybrid Journal   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 5, SJR: 1.11, CiteScore: 3)
ALTEX : Alternatives to Animal Experimentation     Open Access   (Followers: 3)
AMBIO     Hybrid Journal   (Followers: 10, SJR: 1.569, CiteScore: 4)
American J. of Cardiovascular Drugs     Hybrid Journal   (Followers: 16, SJR: 0.951, CiteScore: 3)
American J. of Community Psychology     Hybrid Journal   (Followers: 29, SJR: 1.329, CiteScore: 2)
American J. of Criminal Justice     Hybrid Journal   (Followers: 9, SJR: 0.772, CiteScore: 1)
American J. of Cultural Sociology     Hybrid Journal   (Followers: 18, SJR: 0.46, CiteScore: 1)
American J. of Dance Therapy     Hybrid Journal   (Followers: 5, SJR: 0.181, CiteScore: 0)
American J. of Potato Research     Hybrid Journal   (Followers: 2, SJR: 0.611, CiteScore: 1)
American J. of Psychoanalysis     Hybrid Journal   (Followers: 22, SJR: 0.314, CiteScore: 0)
American Sociologist     Hybrid Journal   (Followers: 16, SJR: 0.35, CiteScore: 0)
Amino Acids     Hybrid Journal   (Followers: 7, SJR: 1.135, CiteScore: 3)
AMS Review     Partially Free   (Followers: 4)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 7, SJR: 0.211, CiteScore: 1)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 6, SJR: 0.536, CiteScore: 1)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Analysis of Verbal Behavior     Hybrid Journal   (Followers: 6)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 32, SJR: 0.978, CiteScore: 3)
Anatomical Science Intl.     Hybrid Journal   (Followers: 3, SJR: 0.367, CiteScore: 1)
Angewandte Schmerztherapie und Palliativmedizin     Hybrid Journal  
Angiogenesis     Hybrid Journal   (Followers: 3, SJR: 2.177, CiteScore: 5)
Animal Cognition     Hybrid Journal   (Followers: 20, SJR: 1.389, CiteScore: 3)
Annales françaises de médecine d'urgence     Hybrid Journal   (Followers: 1, SJR: 0.192, CiteScore: 0)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3, SJR: 1.097, CiteScore: 2)
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4, SJR: 0.438, CiteScore: 0)
Annali dell'Universita di Ferrara     Hybrid Journal   (SJR: 0.429, CiteScore: 0)
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1, SJR: 1.197, CiteScore: 1)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 17, SJR: 1.042, CiteScore: 3)
Annals of Combinatorics     Hybrid Journal   (Followers: 4, SJR: 0.932, CiteScore: 1)
Annals of Data Science     Hybrid Journal   (Followers: 12)
Annals of Dyslexia     Hybrid Journal   (Followers: 10, SJR: 0.85, CiteScore: 2)
Annals of Finance     Hybrid Journal   (Followers: 34, SJR: 0.579, CiteScore: 1)
Annals of Forest Science     Hybrid Journal   (Followers: 7, SJR: 0.986, CiteScore: 2)
Annals of Global Analysis and Geometry     Hybrid Journal   (Followers: 1, SJR: 1.228, CiteScore: 1)
Annals of Hematology     Hybrid Journal   (Followers: 16, SJR: 1.043, CiteScore: 2)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 12, SJR: 0.413, CiteScore: 1)
Annals of Microbiology     Hybrid Journal   (Followers: 11, SJR: 0.479, CiteScore: 2)
Annals of Nuclear Medicine     Hybrid Journal   (Followers: 5, SJR: 0.687, CiteScore: 2)
Annals of Operations Research     Hybrid Journal   (Followers: 10, SJR: 0.943, CiteScore: 2)
Annals of Ophthalmology     Hybrid Journal   (Followers: 13)
Annals of Regional Science     Hybrid Journal   (Followers: 8, SJR: 0.614, CiteScore: 1)
Annals of Software Engineering     Hybrid Journal   (Followers: 13)
Annals of Solid and Structural Mechanics     Hybrid Journal   (Followers: 9, SJR: 0.239, CiteScore: 1)
Annals of Surgical Oncology     Hybrid Journal   (Followers: 15, SJR: 1.986, CiteScore: 4)
Annals of Telecommunications     Hybrid Journal   (Followers: 9, SJR: 0.223, CiteScore: 1)
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1, SJR: 1.495, CiteScore: 1)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5, SJR: 0.834, CiteScore: 2)
Apidologie     Hybrid Journal   (Followers: 4, SJR: 1.22, CiteScore: 3)
APOPTOSIS     Hybrid Journal   (Followers: 9, SJR: 1.424, CiteScore: 4)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2, SJR: 0.294, CiteScore: 1)
Applications of Mathematics     Hybrid Journal   (Followers: 3, SJR: 0.602, CiteScore: 1)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 44, SJR: 0.571, CiteScore: 2)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 18, SJR: 0.21, CiteScore: 1)
Applied Categorical Structures     Hybrid Journal   (Followers: 4, SJR: 0.49, CiteScore: 0)
Applied Composite Materials     Hybrid Journal   (Followers: 51, SJR: 0.58, CiteScore: 2)
Applied Entomology and Zoology     Partially Free   (Followers: 6, SJR: 0.422, CiteScore: 1)
Applied Geomatics     Hybrid Journal   (Followers: 3, SJR: 0.733, CiteScore: 3)
Applied Geophysics     Hybrid Journal   (Followers: 9, SJR: 0.488, CiteScore: 1)
Applied Intelligence     Hybrid Journal   (Followers: 15, SJR: 0.6, CiteScore: 2)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4, SJR: 0.319, CiteScore: 1)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 9, SJR: 0.886, CiteScore: 1)
Applied Mathematics - A J. of Chinese Universities     Hybrid Journal   (Followers: 1, SJR: 0.17, CiteScore: 0)
Applied Mathematics and Mechanics     Hybrid Journal   (Followers: 5, SJR: 0.461, CiteScore: 1)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 66, SJR: 1.182, CiteScore: 4)
Applied Physics A     Hybrid Journal   (Followers: 10, SJR: 0.481, CiteScore: 2)
Applied Physics B: Lasers and Optics     Hybrid Journal   (Followers: 26, SJR: 0.74, CiteScore: 2)
Applied Psychophysiology and Biofeedback     Hybrid Journal   (Followers: 8, SJR: 0.519, CiteScore: 2)
Applied Research in Quality of Life     Hybrid Journal   (Followers: 12, SJR: 0.316, CiteScore: 1)
Applied Solar Energy     Hybrid Journal   (Followers: 22, SJR: 0.225, CiteScore: 0)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 7, SJR: 0.542, CiteScore: 1)
Aquaculture Intl.     Hybrid Journal   (Followers: 26, SJR: 0.591, CiteScore: 2)
Aquarium Sciences and Conservation     Hybrid Journal   (Followers: 2)
Aquatic Ecology     Hybrid Journal   (Followers: 38, SJR: 0.656, CiteScore: 2)
Aquatic Geochemistry     Hybrid Journal   (Followers: 4, SJR: 0.591, CiteScore: 1)
Aquatic Sciences     Hybrid Journal   (Followers: 14, SJR: 1.109, CiteScore: 3)
Arabian J. for Science and Engineering     Hybrid Journal   (Followers: 5, SJR: 0.303, CiteScore: 1)
Arabian J. of Geosciences     Hybrid Journal   (Followers: 2, SJR: 0.319, CiteScore: 1)
Archaeological and Anthropological Sciences     Hybrid Journal   (Followers: 21, SJR: 1.052, CiteScore: 2)
Archaeologies     Hybrid Journal   (Followers: 12, SJR: 0.224, CiteScore: 0)
Archiv der Mathematik     Hybrid Journal   (Followers: 1, SJR: 0.725, CiteScore: 1)
Archival Science     Hybrid Journal   (Followers: 68, SJR: 0.745, CiteScore: 2)
Archive for History of Exact Sciences     Hybrid Journal   (Followers: 7, SJR: 0.186, CiteScore: 1)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 3, SJR: 0.909, CiteScore: 1)
Archive for Rational Mechanics and Analysis     Hybrid Journal   (SJR: 3.93, CiteScore: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 6, SJR: 0.79, CiteScore: 2)
Archives and Museum Informatics     Hybrid Journal   (Followers: 160, SJR: 0.101, CiteScore: 0)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 6, SJR: 1.41, CiteScore: 5)
Archives of Dermatological Research     Hybrid Journal   (Followers: 7, SJR: 1.006, CiteScore: 2)
Archives of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 14, SJR: 0.773, CiteScore: 2)
Archives of Gynecology and Obstetrics     Hybrid Journal   (Followers: 17, SJR: 0.956, CiteScore: 2)
Archives of Microbiology     Hybrid Journal   (Followers: 9, SJR: 0.644, CiteScore: 2)
Archives of Orthopaedic and Trauma Surgery     Hybrid Journal   (Followers: 9, SJR: 1.146, CiteScore: 2)
Archives of Osteoporosis     Hybrid Journal   (Followers: 2, SJR: 0.71, CiteScore: 2)
Archives of Sexual Behavior     Hybrid Journal   (Followers: 10, SJR: 1.493, CiteScore: 3)
Archives of Toxicology     Hybrid Journal   (Followers: 17, SJR: 1.541, CiteScore: 5)
Archives of Virology     Hybrid Journal   (Followers: 5, SJR: 0.973, CiteScore: 2)
Archives of Women's Mental Health     Hybrid Journal   (Followers: 17, SJR: 1.274, CiteScore: 3)
Archivio di Ortopedia e Reumatologia     Hybrid Journal  
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2, SJR: 0.946, CiteScore: 3)
ArgoSpine News & J.     Hybrid Journal  
Argumentation     Hybrid Journal   (Followers: 6, SJR: 0.349, CiteScore: 1)
Arid Ecosystems     Hybrid Journal   (Followers: 2, SJR: 0.2, CiteScore: 0)
Arkiv för Matematik     Hybrid Journal   (Followers: 2, SJR: 0.766, CiteScore: 1)
Arnold Mathematical J.     Hybrid Journal   (Followers: 1, SJR: 0.355, CiteScore: 0)
Arthropod-Plant Interactions     Hybrid Journal   (Followers: 2, SJR: 0.839, CiteScore: 2)
Arthroskopie     Hybrid Journal   (Followers: 1, SJR: 0.131, CiteScore: 0)
Artificial Intelligence and Law     Hybrid Journal   (Followers: 11, SJR: 0.937, CiteScore: 2)
Artificial Intelligence Review     Hybrid Journal   (Followers: 18, SJR: 0.833, CiteScore: 4)
Artificial Life and Robotics     Hybrid Journal   (Followers: 10, SJR: 0.226, CiteScore: 0)
Asia Europe J.     Hybrid Journal   (Followers: 4, SJR: 0.504, CiteScore: 1)
Asia Pacific Education Review     Hybrid Journal   (Followers: 12, SJR: 0.479, CiteScore: 1)
Asia Pacific J. of Management     Hybrid Journal   (Followers: 16, SJR: 1.185, CiteScore: 2)
Asia-Pacific Education Researcher     Hybrid Journal   (Followers: 13, SJR: 0.353, CiteScore: 1)
Asia-Pacific Financial Markets     Hybrid Journal   (Followers: 3, SJR: 0.187, CiteScore: 0)
Asia-Pacific J. of Atmospheric Sciences     Hybrid Journal   (Followers: 19, SJR: 0.855, CiteScore: 1)
Asian Business & Management     Hybrid Journal   (Followers: 9, SJR: 0.378, CiteScore: 1)
Asian J. of Business Ethics     Hybrid Journal   (Followers: 11)
Asian J. of Criminology     Hybrid Journal   (Followers: 6, SJR: 0.543, CiteScore: 1)
AStA Advances in Statistical Analysis     Hybrid Journal   (Followers: 4, SJR: 0.548, CiteScore: 1)
AStA Wirtschafts- und Sozialstatistisches Archiv     Hybrid Journal   (Followers: 5, SJR: 0.183, CiteScore: 0)
ästhetische dermatologie & kosmetologie     Full-text available via subscription  
Astronomy and Astrophysics Review     Hybrid Journal   (Followers: 22, SJR: 3.385, CiteScore: 5)

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Similar Journals
Journal Cover
Aquatic Sciences
Journal Prestige (SJR): 1.109
Citation Impact (citeScore): 3
Number of Followers: 14  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1015-1621 - ISSN (Online) 1420-9055
Published by Springer-Verlag Homepage  [2351 journals]
  • Short-term toxicity effects of Prymnesium parvum on zooplankton community
           composition
    • Abstract: Harmful algal blooms (HABs) can disrupt aquatic communities through a variety of mechanisms, especially through toxin production. Herbivorous and omnivorous zooplankton may be particularly susceptible to HAB toxins, due to their close trophic relationship to algae as grazers. In this study, the acute toxigenic effects of the haptophyte Prymnesium parvum on a zooplankton community were investigated under laboratory conditions. Total zooplankton abundances decreased during 48-h exposure, although species responses to P. parvum densities varied. Changes in community composition were driven by declines in Daphnia mendotae and Keratella spp. abundances, which resulted in an average shift in copepod abundance from 47.1 to 72.4%, and rotifer abundance from 35.0 to 7.1%. Total cladocerans were relatively unchanged in relative abundance (11.1–10.4%), though the dominant cladoceran shifted from Daphnia mendotae (61.3% of cladocerans) to Bosmina longirostris (81.5% of cladocerans). Daphnia mendotae and Keratella spp. are known to be non-selective or generalist feeders and were likely harmed through a combination of ingestion of and contact by P. parvum. Proportional increases in copepod and Bosmina abundances in the presence of P. parvum likely reflect selective or discriminate feeding abilities in these taxa. This study corroborates previous field studies showing that P. parvum can negatively affect zooplankton, reflecting species-specific differences in zooplankton-P. parvum interactions. Such changes can alter zooplankton community composition, leading to substantial food-web consequences and potential long-term ecosystem-level impacts in lakes that experience blooms.
      PubDate: 2019-07-15
       
  • Multi-year trends and determinants of the hydrochemistry of high mountain
           lakes in the Western Italian Alps
    • Abstract: High mountain lakes (HML) provide essential ecosystem services, have tremendous conservation and aesthetic value, and are good model ecosystems to study the ecological consequences of global change. Multi-year (2008–2017) chemical data from 25 HML from the Gran Paradiso National Park (Western Italian Alps) were used to address two specific objectives: (1) assess the major determinants of HML hydrochemistry; (2) identify any multi-years trend attributable to global change. Local trends in climatic variables and NO3−, NH4+, and SO42− deposition were evaluated over the same period as possible drivers of lake chemistry. We were able to explain most of the variance associated to the major ion concentration, but much less of that associated with nutrient content and with variables related to atmospheric deposition (e.g. Cl−, Na+, inorganic N). The explanation of which probably requires studies at a regional scale. As a whole, lake chemistry depends on the interplay of several environmental variables, including the impact of human activities (i.e. point source of organic pollutants). Catchment geology and vegetation cover influence several variables related to weathering processes, which show a general increase over the last 10 years. This general trend can be attributable to climatic variability enhancing weathering processes in lake catchments. However, a concomitant decrease of precipitation amount and the deposition of acidifying compounds may have contributed to the observed trends. Meteorological data were almost unrelated to HML hydrochemistry, suggesting that lake chemical composition would depend more strongly on long-term climatic variations rather than on short-term meteorological events.
      PubDate: 2019-07-02
       
  • Kairomone-induced changes in mosquito life history: effects across a food
           gradient
    • Abstract: The aquatic immature stages of species with complex life histories exhibit a range of defense mechanisms in response to predator released kairomones (PRK). Employing these costly mechanisms often results in delayed metamorphosis. Larvae of the house mosquito Culex pipiens (Linnaeus) show a rare exception of accelerated metamorphosis in response to kairomones originated from the mosquitofish Gambusia affinis (Baird and Girard). In a series of lab experiments we examined whether this response is context-dependent with respect to food availability (i.e. applied only when food is abundant and cost is low). We examined life history variables of C. pipiens larvae, reared at different levels of food availability, either with or without PRK. We further examined the effect of PRK on the foraging behavior of the larvae at different instars. We also examined the effect of PRK-induced behavior on larvae survival under actual predation. We showed that the response of C. pipiens larvae to PRK was independent of food availability. Larvae exposed to PRK were less active and survived longer when exposed to direct predation. Exposure to both PRK and small food amounts also resulted in reduced adult size and survival period. The effects of food and PRK were independent of one another. We argue that for organisms with short development time, such as mosquitoes, decreasing time to metamorphosis may be the main feasible refuge from increased predation risk. Hence, Culex larvae exploit their capability for rapid development rate as a main anti-predator mechanism, minimizing the time spent in high-risk environments by accelerating metamorphosis, regardless of available resources, at the expense of other life history traits.
      PubDate: 2019-06-18
       
  • Trophic cascade strength is influenced by size frequency distribution of
           primary consumers and size-selective predation: examined with mesocosms
           and modeling
    • Abstract: Understanding variation in trophic cascades is critical for developing management strategies for invasive and introduced species as well as in designing biomanipulation experiments. We evaluated, in fish driven trophic cascades, the responses of invertebrate biomass, body size, and production both experimentally and through a model. Experimental mesocosm treatments of small (Moina), large (Daphnia pulex), and mixed size zooplankton communities were characterized with and without size-selective fish (bluegill, Lepomis macrochirus). Experimental responses were typical of trophic cascades showing reduced biomass, body size and production of zooplankton and generally enhanced chlorophyll a. Although zooplankton biomass was similarly reduced in all fish treatments, production for the fish D. pulex treatment was lower than the other fish treatments because larger taxa have a lower ratio of production to biomass (P/B). As would be expected based on zooplankton production among fish treatments, response of chlorophyll a in treatments with D. pulex was faster and final concentration higher than in Moina or mixed size treatments. A model of changes in production under a range of reductions in body size and/or biomass, from no reduction to 99% reduction, supported experimental results indicating invertebrate production can be resilient to reduction of biomass when body size is reduced. Strength of trophic cascades may therefore, in part, be related to interactions among reduction in biomass, size-selective predation, and size frequency distribution and plasticity of prey community. Because size-selective predation is a common trait in trophic cascades, some level of compensation is likely in most trophic cascades.
      PubDate: 2019-05-16
       
  • Microbial planktonic communities in lakes from a Patagonian basaltic
           plateau: influence of the water level decrease
    • Abstract: In this study we analyzed the structure of the microbial planktonic communities in 16 lakes located in one of the Patagonian plateaus. In these environments picoplankton constitute a key component of the food webs. We compared lakes with different regimes (clear vegetated and turbid), in periods with contrasting hydrological conditions. Samplings were conducted during late summer in 2015 (higher water levels), 2016 and 2017 (lower water levels). In each lake we measured limnological variables and quantified picoplankton by flow cytometry. Differences in picoplankton structure among lakes were associated with their regime and hydrological conditions. We found higher abundances of heterotrophic bacterioplankton (HB) in more turbid and eutrophic lakes; these lakes also showed higher abundances of both bacterial fractions analyzed (high and low nucleic-acid content). Clear vegetated oligotrophic lakes showed the lowest photosynthetic picoplankton abundances and higher densities of PE-rich picocyanobacteria (Pcy). All lakes presented PE-rich cells and picoeukaryotes (Peuk), the latter being the most frequent group in all the environments and the most abundant in turbid ones. PC-rich Pcy appeared only in clear vegetated, organic turbid and inorganic turbid, showing one or two cytometric populations. Clear vegetated lakes with water level reduction show an increase of HB, PC-rich cells and Peuk abundances. We provided evidences that picoplankton structure is influenced by lake regime, and in some lakes the shift from clear vegetated to turbid states strongly affects the structure of these communities.
      PubDate: 2019-05-06
       
  • Global warming affects nutrient upwelling in deep lakes
    • Abstract: Measures to reduce lake phosphorus concentrations have been encouragingly successful in many parts of the world. After significant eutrophication in the twentieth century, nutrient concentrations have declined in many natural settings. In addition to these direct anthropogenic impacts, however, climate change is also altering various processes in lakes. Its effects on lacustrine nutrient budgets remain poorly understood. Here we investigate the total phosphorus (TP) concentrations in the epilimnion of the meromictic Lake Zug under present and future climatic conditions. Results are compared with those of other deep lakes. Data showed that TP transported from the hypolimnion by convective winter mixing was the most important source of TP for the epilimnion, reaching values more than ten times higher than the external input from the catchment. We found a logarithmic relationship between winter mixing depth (WMD) and epilimnetic TP content in spring. Warming climate affects WMD mainly due to its dependence on autumn stratification. Model simulations predict a reduction of average WMD from 78 (current) to 65 m in 2085 assuming IPCC scenario A2. Other scenarios show similar but smaller changes in the future. In scenario A2, climate change is predicted to reduce epilimnetic TP concentrations by up to 24% during warm winters and may consequently introduce significant year-to-year variability in primary productivity.
      PubDate: 2019-04-29
       
  • The El Niño Southern Oscillation (ENSO) is the main source of variation
           for the gamma diversity of plankton communities in subtropical shallow
           lakes
    • Abstract: We determined the variation in the composition of plankton communities (zooplankton, phytoplankton, and ciliates) in subtropical lakes at different temporal scales, in relation to the seasons (dry and rainy seasons), as well as at finer (among months) and broader (ENSO—among El Niño, La Niña, and normal climate events) scales. Using a 16-year time-series dataset, we tested the hypothesis that seasonal variation would explain most of the gamma diversity of these plankton communities. We also investigated the environmental and temporal factors responsible for the variations in composition and species turnover. The scale related to dry and rainy seasons explained a considerable percentage of the gamma diversity and variation partitioning, showed that compositional changes occurred mainly over broader temporal scales. Environmental factors varying among seasons and ENSO events explained changes in composition, although some communities did not respond to the environment. Our results suggest that niche and stochastic processes operating at temporal scales correlated with ENSO climate events contributed to changes in species composition. Hence, climate anomalies might be important to maintain diversity in areas with reduced or loss of the natural variations in environmental conditions. Our results also suggest that, although communities show similar patterns of variation in composition, they might respond in a different degree to environmental and temporal factors. Thus, while niche-associated (environment) and stochastic (time) processes drove the phytoplankton, stochastic processes were more important for zooplankton, whereas neither were important for ciliates.
      PubDate: 2019-04-27
       
  • The relative importance of weather and nutrients determining phytoplankton
           assemblages differs between seasons in large Lake Taihu, China
    • Abstract: Climate change affects seasonal weather patterns, but little is known about the consequent effects on phytoplankton assemblage variation. We studied the changes in phytoplankton assemblages, expressed as morpho-functional groups, during four seasons over the past two decades in large shallow eutrophic Lake Taihu, China. During this period, both climate and nutrient levels changed in the lake. Wind speed declined significantly from 1997 to 2016 in all seasons, while global radiation increased significantly in spring and winter. Phosphorus and chlorophyll a concentrations showed a significant increasing trend in all seasons, especially in summer and autumn. Diatoms, mainly Aulacoseira and Asterionella, increased during late winter and early spring. Multiple stepwise regression analysis and non-metric multidimensional scaling indicated that climatic variables (i.e., decreasing wind speed and increasing global radiation) were the main drivers of phytoplankton assemblage variance in winter and early spring. An increase in the dominance of cyanobacteria (mainly Microcystis spp.) in summer and autumn was mainly related to changes in phosphorus. Our results indicate that both nutrients and climatic variables were major drivers of the observed changes in phytoplankton assemblages, differing in importance between seasons. The differential response of phytoplankton community variation to future environmental change in the different seasons needs to be taken into account when evaluating the long-term changes in phytoplankton.
      PubDate: 2019-04-26
       
  • Spatial and seasonal variation in N 2 -fixing cyanobacteria in Poyang Lake
           from 2012 to 2016: roles of nutrient ratios and hydrology
    • Abstract: Large river floodplain systems provide a variety of societal, economic and biological benefits and are undergoing extensive and intensive environmental deterioration. Eutrophication coupled with undesired harmful cyanobacterial blooms is one of the most widespread and severe problems in floodplain ecosystems. However, our knowledge about cyanobacteria, particularly the biogeography of N2-fixing (Nfix) cyanobacteria in shallow floodplain lakes, is very limited, and the relationships of cyanobacterial blooms with nutrient ratios and hydrological alterations remain unclear. We used a comprehensive database of field data compiled over several years (2012 to 2016) to compare the biomass and distribution of Nfix cyanobacteria between the northern (high water velocity) and southern (low water velocity) parts of Poyang Lake and to investigate the roles of hydrology and the critical nutrient mass ratios of total nitrogen:total phosphorus (TN:TP) and dissolved inorganic nitrogen:orthophosphate (DIN:PO4-P) as significant predictors of Nfix cyanobacterial biomass and distribution in eutrophic floodplain ecosystems. Dolichospermum spp. (Dolichospermum flos-aquae, D. azotica, D. circinalis, and D. spiroides) were the most widely distributed and frequent diazotrophic cyanobacteria in the regions considered in this study, followed by Aphanizomenon flos-aquae. The Nfix cyanobacterial biomass was generally low (mean = 0.32 mg/l) across Poyang Lake and was lower in the north than in the south. Using Spearman’s rank correlations, we found that this pattern may be attributed to the high turbidity and washout from the high velocity of water flow in the north. The filament length and heterocyst frequency of Dolichospermum spp. in the lake were also strongly linked to variations in hydrological characteristics and water temperature. Our results imply that the nutrient mass ratios are more important determinants of Nfix cyanobacterial biomass than hydrology in the south part of the lake. The critical TN:TP mass ratio for the Nfix cyanobacterial communities in Poyang Lake is approximately 20, and the critical DIN:PO4-P mass ratio in the lake is approximately 40. Our analysis provides new information regarding the occurrence of bloom-forming Nfix cyanobacteria in Yangtze River floodplain lakes and thus fills an important knowledge gap in subtropical freshwater ecosystems.
      PubDate: 2019-04-22
       
  • Observations and modeling of the surface seiches of Lake Tahoe, USA
    • Abstract: A rich array of spatially complex surface seiche modes exists in lakes. While the amplitude of these oscillations is often small, knowledge of their spatio-temporal characteristics is valuable for understanding when they might be of localized hydrodynamic importance. The expression and impact of these basin-scale barotropic oscillations in Lake Tahoe are evaluated using a finite-element numerical model and a distributed network of ten high-frequency nearshore monitoring stations. Model-predicted nodal distributions and periodicities are confirmed using the presence/absence of spectral power in measured pressure signals, and using coherence/phasing analysis of pressure signals from stations on common and opposing antinodes. Surface seiches in Lake Tahoe have complex nodal distributions despite the relative simplicity of the basin morphometry. Seiche amplitudes are magnified on shallow shelves, where they occasionally exceed 5 cm; elsewhere, amplitudes rarely exceed 1 cm. There is generally little coherence between surface seiching and littoral water quality. However, pressure–temperature coherence at shelf sites suggests potential seiche-driven pumping. Main-basin seiche signals are present in attached marinas, wetlands, and bays, implying reversing flows between the lake and these water bodies. On the shallow sill connecting Emerald Bay to Lake Tahoe, the fundamental main-basin seiche combines with a zeroth-mode harbor seiche to dominate the cross-sill flow signal, and to drive associated temperature fluctuations. Results highlight the importance of a thorough descriptive understanding of the resonant barotropic oscillations in any lake basin in a variety of research and management contexts, even when the magnitude of these oscillations tends to be small.
      PubDate: 2019-04-16
       
  • Importance of mixotrophic flagellates during the ice-free season in lakes
           located along an elevational gradient
    • Abstract: Mixotrophy seems to be widespread among phytoplankton, but whether this strategy is more relevant in oligotrophic lakes remains unclear. Here, we tested the hypothesis that the relative abundance of mixotrophic flagellates in lakes increases along an elevational gradient paralleling increasingly oligotrophic conditions. For this purpose, 12 lakes located between 575 and 2796 m above sea level were sampled in summer and fall to include two different seasonal windows in phytoplankton dynamics and environmental conditions. The degree of mixotrophy in phytoplankton was estimated in tracer experiments using fluorescently-labeled bacteria and done with composite samples collected in the euphotic zone and in samples obtained from the chlorophyll-a maximum. The results indicated the existence of a positive trend particularly in summer in the relative abundance of mixotrophic flagellates with elevation, however, this trend was not linear, and exceptions along the elevational gradient were found. Changes in the relative abundance of mixotrophic flagellates were related with significant changes in water transparency, DOC and phosphorus concentrations, as well as in bacterial and flagellate abundance. Overall, our results reveal that the harsh growth conditions found in oligotrophic high mountain lakes favor a mixotrophic trophic strategy among phytoplankton.
      PubDate: 2019-04-16
       
  • Riparian vegetation subsidizes sea lamprey ammocoetes in a nursery area
    • Abstract: Fluxes of organic matter (OM) from terrestrial ecosystems subsidize stream food webs, which support the production of ecologically and economically important species such as the sea lamprey Petromyzon marinus. Debris have been previously observed in the gut contents of sea lamprey ammocoetes, but their origin and/or the nutritional sources assimilated are still poorly known. We used carbon (δ13C: 13C/12C) and nitrogen (δ15N: 15N/14N) stable isotopes to identify the main OM sources supporting the production of ammocoetes in a tributary of the Minho River (NW-Iberian Peninsula). Ammocoetes δ13C and C:N values increased with length. Smaller individuals likely assimilated more 13C- depleted sources such as fresh or decaying plant material. The increase in the C:N values with length suggests that ammocoetes accumulate lipids to support their metamorphosis and recruitment into an adult animal. Ammocoetes smaller than 30 mm presented an unusual variability for both δ15N and δ13C values, with values varying between 3.2‰ and 17.8‰ for δ15N and between − 38‰ and − 25.5‰ for δ13C in the same sampling site. This suggests that factors such as organic pollution inputs or time to the first feeding may have contributed to the observed variability. Detritus from the adjacent riparian vegetation was identified as the main food source assimilated by sea lamprey ammocoetes. The stable isotope mixing model (95% CI) indicates that the relative contribution of decaying riparian plants detritus varied between 38–59% and 55–73% at the end of the summer decreasing towards the end of the winter (2–34%). The relative contribution of other terrestrial-derived OM (i.e. fresh riparian detritus and particulate OM with terrestrial origin) was only relevant (> 40%) at the end of the winter. This study shows that there is a strong connectivity between the stream food web and the adjacent riparian ecosystem, and that protection of both riparian and catchment forest cover are essential to preserve terrestrial-aquatic linkages which can support the development of sea lamprey ammocoetes.
      PubDate: 2019-04-13
       
  • Macroinvertebrate diversity and rarity in non-glacial Alpine streams
    • Abstract: Alpine landscapes are being transformed through the rapid recession of glaciers, resulting in the development of numerous non-glacial headwater streams inhabited by a diverse assemblage of macroinvertebrates. We examined spatial patterns in biodiversity and rarity of macroinvertebrates in 41 non-glacial streams from five glacierized catchments in the Swiss Alps undergoing rapid glacial recession over the last decades. Water physico-chemistry and food resources (periphyton, benthic organic matter) varied widely among streams within each catchment, while no significant differences occurred among catchments. Variability in community composition was similar among streams within each catchment but differed among catchments, reflecting differences in catchment-scale species pools due to biogeographical context and season. Overall, 101 taxa from ca 33,000 individuals collected were identified in the streams with 7–33 taxa found in individual streams. Some 64% of the taxa comprised less than 5% of the total abundances at the streams (rare in abundance) with 78% of the taxa being represented by less than 5% of the most common taxon (Baetis sp.), whereas 47% of the taxa were found in less than 10% of the streams (rare in distribution). No taxon was found at all sites (maximum presence at 85% of the sites), while 15% of the taxa were found at 50% of the sites or more. However, analyzing the rank-abundance distribution showed that rarity was less prevalent than previously shown in other ecosystems. The results indicated that community assembly of alpine headwater streams is a complex interaction between environmental properties (habitat filtering), habitat stability coupled with dispersal (source sink dynamics), and time since deglaciation (island biogeography). Integrating these processes is essential towards understanding ongoing colonization events in headwater streams of alpine catchments as glaciers continue to recede.
      PubDate: 2019-04-13
       
  • Geomorphologic heterogeneity influences dry-season soil CO 2 efflux by
           mediating soil biophysical variables in a tropical river valley
    • Abstract: Riparian landscapes are characterized by heterogeneous geomorphological structures such as erosive and depositional habitats, and therefore, may have variable soil biophysical properties. The heterogeneity in geomorphological structures and related biophysical properties would exert spatial variations in the soil CO2 efflux (SCE). However, studies assessing the relative control of biophysical variables on the SCE under such complex landscapes of dry tropical ecosystems are limited. Therefore, we assessed the effect of heterogeneity in geomorphological structures on SCE, and identified the key biophysical variables governing SCE along the riparian landscapes. The SCE, soil organic C (SOC), microbial biomass C (MBC) and pH were found to vary significantly (P < 0.05) along riparian habitats, and SCE was found 73% higher at erosive than depositional habitats. SOC was found as a prominent regulator of SCE which alone explained about 80% of the variability in SCE. Moreover, soil moisture, fine particles, pH and MBC also showed strong control on SCE along riparian landscapes. Stepwise regression analysis revealed that after excluding SOC as a main variable, soil moisture explained 32% of the variability in SCE at overall landscape level whereas fine particles and MBC explained 78% and 23% of the variability in SCE at erosive and depositional habitats, respectively. Overall, results indicate that erosive habitats are the major source of SCE, and variation in biophysical variables is greatly affecting the SCE at these habitats. Therefore, further assessment of interactions of SCE, soil biophysical parameters and their regulatory components such as hydrology, vegetation and anthropogenic activities at micro—(site and land-use) as well as macro—(landscape) scales would help to understand the soil C dynamics along the heterogeneous riparian landscapes under climate change scenarios.
      PubDate: 2019-04-13
       
  • The role of patch size in ecosystem engineering capacity: a case study of
           aquatic vegetation
    • Abstract: Submerged aquatic plants are ecosystem engineers that are able to modify their habitat. However, the role of patch size in the engineering capacity of aquatic plants has not yet been fully investigated, while it could be essential for elucidating the consequences of plant presence. Our objectives were to investigate the effects of patch size on plant-flow-sediment interactions in lotic ecosystems and to determine whether these effects differed according to environmental characteristics. We performed in situ measurements of velocity and grain size along natural patches of increasing length (L) at two sites presenting different flow and sediment characteristics. Our results indicated that a minimum patch size was needed to induce in-patch reduction of the time averaged velocity component in the flow direction (i.e. streamwise velocity) and fine sediment accumulation. Streamwise velocity decreased linearly with L independently of the site conditions. The sediment texture was instead dependent on site conditions: for the site characterized by higher velocity and coarser sediment, the sediment grain size exponentially decreased with L, reaching a minimum value at L ≥ 1.0 m, while for the site characterized by lower velocity and finer sediment, it reached a minimum value already at L > 0.3 m. This study demonstrated that a minimal patch size is required to trigger the ecosystem engineering capacity of aquatic plant patches in lotic environments and that this capacity increases with patch length. Small patches induce little to no modification of the physical habitat, with possible negative feedbacks for plants. With increasing patch size, the habitat modifications induced by plants become more important, potentially triggering positive feedbacks for plants.
      PubDate: 2019-04-12
       
  • Living on the edge: reproduction, dispersal potential, maternal effects
           and local adaptation in aquatic, extremophilic invertebrates
    • Abstract: Isolated extreme habitats are ideally suited to investigate pivotal ecological processes such as niche use, local adaptation and dispersal. Extremophilic animals living in isolated habitats face the problem that dispersal is limited through the absence of suitable dispersal corridors, which in turn facilitates local adaptation. We used five rotifer isolates from extremely acidic mining lakes with a pH of below 3 as model organisms to test whether these isolates are acidotolerant or acidophilic, whether they survive and reproduce at their niche edges (here pH 2 and circum-neutral pH) and whether local adaptation has evolved. To evaluate potential dispersal limitation, we tested whether animals and their parthenogenetic eggs survive and remain reproductive or viable at unfavourable pH-conditions. All five isolates were acidophilic with a pH-optimum in the range of 4–6, which is well above the pH (< 3) of their lakes of origin. At unfavourable high pH, in four out of the five isolates parthenogenetic females produced a high number of non-viable eggs. Females and eggs produced at favourable pH (4) remained vital at an otherwise unfavourable pH of 7, indicating that for dispersal no acidic dispersal corridors are necessary. Common garden experiments revealed no clear evidence for local adaptation in any of the five isolates. Despite their acidophilic nature, all five isolates can potentially disperse via circum-neutral water bodies as long as their residence time is short, suggesting a broader “dispersal niche” than their realized niche. Local adaptation might have been hampered by the low population sizes of the rotifers in their isolated habitat and the short time span the mining lakes have existed.
      PubDate: 2019-04-09
       
  • Sediment size influences habitat selection and use by groundwater
           macrofauna and meiofauna
    • Abstract: Understanding environmental factors that influence obligate groundwater dwelling (stygobiotic) fauna is crucial for groundwater ecosystem monitoring and management. Field studies have indicated geological factors are a major influence on the abundance and richness of stygofauna, however the precise mechanisms and true influence of the aquifer sediment matrix on biota is unclear. In this study we examined the habitat use and preferences, in terms of sediment particle sizes, of stygobiotic meiofauna (Harpacticoida and Cyclopoida Copepoda), and macroinvertebrates (Amphipoda and Syncarida) using laboratory microcosms. We first tested the ability of each taxon to use (move into) clay (< 0.06 mm), sand (0.3–0.7 mm) and gravel sediments (2–4 mm). Subsequently, the preference for each sediment was compared by examining the distribution of animals in microcosms containing two different sediment types. Both the harpacticoids and cyclopoids were able to use clay, whereas larger amphipods and syncarids mostly remained on the sediment surface. All taxa were able to use sand and gravel substrates. Amphipods preferred gravel over sand and clay. Both copepods and syncarids preferred sand and gravel over clay, but showed no preference between gravel and sand. This study demonstrates the general inability of some stygobiotic macroinvertebrates to use clay sediments and overall differences in sediment use among stygobiotic meio- and macrofauna. From these findings, the typically heterogenous distributions and diversity of stygofauna observed in field studies may be related to variability in sediment composition.
      PubDate: 2019-04-04
       
  • α and β diversity of fishes in relation to a gradient of habitat
           structural complexity supports the role of environmental filtering in
           community assembly
    • Abstract: α-diversity often responds to habitat structural complexity as a unimodal function. In aquatic systems, increasing density of aquatic vegetation creates more habitat structural complexity for fishes, but only up to a certain threshold, beyond which fish abundance and diversity are restricted by reduced space. As a result, species turnover and nestedness should be observed over habitat structural complexity gradients, reflecting the sorting of species according to aspects of their environment. We investigated the relationship of fish α and β diversity along gradients of habitat structural complexity created by aquatic vegetation in the floodplain of Upper Paraná River. We collected a total of 1832 fishes (24 species) along vegetation density gradients. Our results revealed that α diversity peaked at intermediate levels of habitat structural complexity where interstitial spaces were numerous but no so small as to limit occupancy by most fishes. Low α diversity was associated with lower habitat structural complexity, as commonly reported, and this may result from the influence of predation mortality or threat where there is less physical structure that provides refuge from predators and interference with predator lines of sight for prey detection. Fish diversity is low in patches with high habitat structural complexity because small interstitial spaces restrict fish size and dissolved oxygen concentration sometimes is low. Aquatic vegetation density in floodplain habitats therefore functions as a strong environmental filter influencing spatial patterns of fish α and β diversity.
      PubDate: 2019-03-23
       
  • Spatial and temporal variability in water transparency in Yunnan Plateau
           lakes, China
    • Abstract: Water transparency (represented by Secchi disk depth, SDD), a key physical feature of lake ecosystems, is directly controlled by optically active substances, including organic matter (concentration and composition) and phytoplankton biomass which are closely related to eutrophication and climate warming. Here, we examined the trends in SDD variation and the driving mechanisms based on short-term (35 lakes, July‒September 2017) and long-term (3 lakes, 1982‒2016) datasets covering lakes with different trophic states on the Yunnan Plateau. In the short-term dataset, increases in organic matter content, phytoplankton biomass and trophic state reduced the SDD. In the long-term dataset, the annual SDD decreased significantly in all three lakes. Significant increases occurred in phytoplankton biomass in eutrophic Lake Dianchi, both phytoplankton biomass and organic matter content in oligo-mesotrophic Lake Erhai, and organic matter content in oligotrophic Lake Fuxianhu over time, and these increases were related to increased trophic state (or change in nutrient level) and/or possibly to climate warming. Furthermore, phytoplankton biomass and organic matter content were important direct driving factors for reduced SDD in eutrophic Lake Dianchi and oligotrophic Lake Fuxianhu, respectively, while the interaction of these two factors was the most important factor in oligo-mesotrophic Lake Erhai. These results implied that eutrophication and climate warming could regulate SDD by changing organic matter concentration and/or phytoplankton biomass, which may depend on the lacustrine trophic state. However, further studies across larger geographical scales and more lakes are needed to confirm these results.
      PubDate: 2019-03-19
       
  • Hydrological fluctuations modulate phototrophic responses to nutrient
           fertilization in a large and shallow lake of Southwest China
    • Abstract: Lake nutrient budgets and hydrology are being altered by human activities and climate change, yet little is known of how fertilization and hydrologic mechanisms interact to structure assemblages of primary producers. Here, we present sediment records from a large shallow lake in Southwest China to separate the relative importance of nutrients and hydrological fluctuation in regulating the abundance and composition of primary producers during the twentieth century, with a focus on their differential effects on diatoms and cyanobacteria. Shifts in sedimentary particle-size distribution were consistent with the documented events of hydrological regulation during ~ 1953–1971 and subsequent changes in water level associated with severe droughts. Nutrient enrichment since ~ 1965 resulted in a significant increase in the abundance of total phototrophs (pheophytin a, β-carotene) as inferred from pigment analyses, with stronger responses of cyanobacteria (echinenone, zeaxanthin) over siliceous algae (diatoxanthin). Fossil diatom assemblages revealed a pronounced replacement of benthic taxa by eutrophic and planktonic species (e.g., Fragilaria crotonensis) since ~ 1973, but we observed a significant increase of small benthic Fragilaria sensu lato taxa following ~ 2005, which generally corresponded with a moderate increase in fossil pigments. Although eutrophication was the paramount predictor of changes in phototrophs during the last century, variation in lake hydrology due to climate and water management also modulated phototroph abundances and, more recently, diatom assemblages. Specifically, our sediment evidence suggests that hydrological fluctuation has overridden fertilization by nutrients in structuring diatom composition, leading to a heterogeneous response of cyanobacteria and diatoms to external forcing of this shallow lake.
      PubDate: 2019-03-19
       
 
 
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