Earth: New pathway proposed for ancient flood: Pulse of fresh meltwater may have triggered 1,200-year cold snap

Science News ◽  
2012 ◽  
Vol 182 (13) ◽  
pp. 11-11
Author(s):  
Erin Wayman
Keyword(s):  
2020 ◽  
Vol 639 ◽  
pp. 169-183
Author(s):  
P Matich ◽  
BA Strickland ◽  
MR Heithaus

Chronic environmental change threatens biodiversity, but acute disturbance events present more rapid and immediate threats. In 2010, a cold snap across south Florida had wide-ranging impacts, including negative effects on recreational fisheries, agriculture, and ecological communities. Here, we use acoustic telemetry and historical longline monitoring to assess the long-term implications of this event on juvenile bull sharks Carcharhinus leucas in the Florida Everglades. Despite the loss of virtually all individuals (ca. 90%) within the Shark River Estuary during the cold snap, the catch per unit effort (CPUE) of age 0 sharks on longlines recovered through recruitment within 6-8 mo of the event. Acoustic telemetry revealed that habitat use patterns of age 0-2 sharks reached an equilibrium in 4-6 yr. In contrast, the CPUE and habitat use of age 3 sharks required 5-7 yr to resemble pre-cold snap patterns. Environmental conditions and predation risk returned to previous levels within 1 yr of the cold snap, but abundances of some prey species remained depressed for several years. Reduced prey availability may have altered the profitability of some microhabitats after the cold snap, leading to more rapid ontogenetic shifts to marine waters among sharks for several years. Accelerated ontogenetic shifts coupled with inter-individual behavioral variability of bull sharks likely led to a slower recovery rate than predicted based on overall shark CPUE. While intrinsic variation driven by stochasticity in dynamic ecosystems may increase the resistance of species to chronic and acute disturbance, it may also increase recovery time in filling the diversity of niches occupied prior to disturbance if resistive capacity is exceeded.


2009 ◽  
Vol 160 (5) ◽  
pp. 124-128
Author(s):  
Claudio Defila

Although the year 2008 in Switzerland belongs to the ten to twelve warmest years since the beginning of measurements, the effects on the development of the vegetation were not very striking. An extreme excess of heat was never registered except in the winter months and in May. The mild winter simply had an effect on the flowering of the hazel, occurring early to very early. Besides this, most of the phenological spring phases were observed at the normal point of time. However, at some observation stations, a small number of phenological phases showed a completely unusual date of occurrence. These were observed very late or even extremely late (new records). Because of the fact that this phenomenon was not only observed at one single phenological phase, showing no spatial pattern and no height dependence, no explanation was found for this extraordinary behavior of these plants. This clearly reflects, despite intensive research on phenology during the last years, that many natural processes are until now not or not yet understood by man. According to the changing weather, the development of the vegetation showed neither a consistent nor an outstanding pattern in the summer. However, the early leaf-fall of the beech was quite striking, caused by the cold snap at the beginning of October. The year 2008 can be considered as a normal phenological year, except the early flowering of the hazel, the inexplicable records (late observations) and the early leaf-fall of the beech.


2021 ◽  
Author(s):  
Aifang Chen ◽  
Junguo Liu ◽  
Matti Kummu ◽  
Olli Varis ◽  
Qiuhong Tang ◽  
...  

2014 ◽  
Vol 117 ◽  
pp. 64-78 ◽  
Author(s):  
F.N. Krencker ◽  
S. Bodin ◽  
R. Hoffmann ◽  
G. Suan ◽  
E. Mattioli ◽  
...  

2014 ◽  
Vol 40 (2) ◽  
pp. 455-462 ◽  
Author(s):  
Elizabeth C. Minor ◽  
Brandy Forsman ◽  
Stephanie J. Guildford

Wetlands ◽  
2014 ◽  
Vol 34 (5) ◽  
pp. 927-942 ◽  
Author(s):  
Michael Murray-Hudson ◽  
Piotr Wolski ◽  
Frances Murray-Hudson ◽  
Mark T. Brown ◽  
Keotshephile Kashe

2021 ◽  
Author(s):  
Erica L. Johnson ◽  
Erin F. Abernethy ◽  
J. Checo Colón-Gaud

Abstract Floodplains of the southeastern United States exhibit high biological productivity, maintained by periodic floodplain inundation as a result of seasonal flooding. To examine the relationship between biological productivity and seasonal flooding following periods of drought, we quantified aquatic macroinvertebrate communities monthly in an inundated floodplain during the annual flood pulse (December-April) in two years, one following a multi-year drought and one following a larger than average flooding event. We predicted that floodplain communities would differ in richness, biomass, and community composition between years and that differences would be driven by discharge at the main stem and organic matter availability. We collected macroinvertebrates from the floodplain of the Altamaha River, an unimpounded 6th order river in the Coastal Plain region of the southeastern US that experiences floodplain connectivity. With invertebrates identified to genus, we elucidated richness, abundance, biomass, community composition, and functional feeding group. Richness was generally higher in the drought year but decreased throughout the flood pulse, while during the flood year richness was lower and increased. Biomass decreased throughout the flood pulse following the drought year and increased during the flood year. There was a high degree of overlap in invertebrate community composition based on abundance data during both years of the study with collector gatherers being the most highly abundant functional feeding group. As climate change impacts (i.e., severe droughts) become more common, it is critical to investigate how aquatic communities are responding to increasingly unpredictable flow conditions in unimpounded and seemingly unaltered rivers.


2014 ◽  
Vol 86 (3) ◽  
pp. 1359-1372 ◽  
Author(s):  
CLARICE C. NOVA ◽  
VANESSA G. LOPES ◽  
LEONARDO COIMBRA E SOUZA ◽  
BETINA KOZLOWSKY-SUZUKI ◽  
TALITA A.A. PEREIRA ◽  
...  

Rotifers have often been used as indicators of sudden changes in physical and chemical features of the aquatic environment. Such features vary greatly during flood pulse events in small lakes connected to major floodplains. However, few are the studies that investigate the consequences of the flood pulse in rotifer species composition, abundance, richness and diversity, especially in Amazonian lakes. We analyzed samples from a small blackwater lake of an “igarapé” connected permanently to the Negro river, in Central Amazonia. Samples were taken twice a year for two years, comprising flooding and receding periods of the flood pulse. Rotifer abundance increased significantly after draught events, and electrical conductivity and turbidity were intrinsically related to such variation. Species composition also changed from flooding to receding periods. Some taxa, such as Brachionus zahniseri reductus and Lecane remanei were restricted to receding periods, while Brachionus zahniseri, Brachionus gillardi and Lecane proiecta were only present during flooding. A shift in the composition of rotifer families was observed from one period to another, showing the effect of renewing waters of the flood pulse. These results suggest that the flood pulse acts as a driving force and stressing condition, considerably altering rotifer community dynamics, either changing species composition or decreasing abundance.


2012 ◽  
Vol 72 (3) ◽  
pp. 545-552 ◽  
Author(s):  
CT. Callil ◽  
D. Krinski ◽  
FA. Silva

The unionid Anodontites trapesilais (Lamarck, 1819) like most freshwater mussels is a parasite of fish. So it is trivial to assume that the availability of hosts is an important factor for the maintenance of unionoid populations. What seems obvious is not always so easy to demonstrate. This study proposes to investigate the effects of abiotic and biotic variables related to the incubation of larvae in A. trapesialis. For this, we estimate different biological indexes and try to capture the dimensionality of the fish, along with the temporal variation of environmental variables. From the application of a CCA, it was demonstrated that there was a synchronicity among the factors and variables proposed here, and we infer that the flood pulse acts as a synergistic factor in this process.


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