lake mývatn
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Author(s):  
Joseph S. Phillips ◽  
Guðni Guðbergsson ◽  
Anthony R Ives

Quantifying temporal variation in demographic rates is a central goal of population ecology. In this study, we analyzed a multidecadal age-structured time series of Arctic charr (Salvelinus alpinus) abundance in Lake Mývatn, Iceland, to infer the time-varying demographic response of the population to reduced harvest in the wake of the fishery's collapse. Our analysis shows that while survival probability of adults increased following the alleviation of harvesting pressure, per capita recruitment consistently declined over most of the study period, until the final three years when it began to increase. The countervailing demographic trends resulted in only limited directional change in the total population size and population growth rate. Rather, the population dynamics were dominated by large interannual variability and a shift towards an older age distribution. Our results are indicative of a slow recovery of the population after its collapse, despite the rising number of adults following relaxed harvest. This underscores the potential for heterogeneous demographic responses to management efforts due to the complex ecological context in which such efforts take place.


2021 ◽  
Author(s):  
Joseph S Phillips ◽  
Amanda R McCormick ◽  
Jamieson C Botsch ◽  
Anthony R Ives

Characterizing the dynamics of energy flow through ecosystems requires quantifying the degree to which primary and secondary production are coupled. This coupling is expected to be tight in ecosystems with high internal production relative to external carbon and energy inputs. We experimentally quantified the dependence of aquatic insect emergence on fresh primary production, specifically for the midge population in Lake Myvatn, Iceland. Using field mesocosms, we manipulated algal primary production by reducing light availability via shading. We then used dissolved oxygen incubations to estimate fluxes of carbon through photosynthesis (i.e., gross primary production or "GPP") over the course of the experiment. We found that elevated GPP was associated with higher emergence rates of adults, as judged both by comparison of emergence across the experimental shading treatments and estimates of in situ GPP within the mesocosms. Furthermore, larger adults emerged earlier than smaller ones, suggesting that asymmetries in resource availability among individuals affected the timing of emergence. Nonetheless, midge emergence was substantial under light-limiting conditions, indicating that while midges benefit from primary production contemporaneous with larval development, they are also capable of completing their life cycles on carbon already existing in the organic matter pool. Our results show that even in systems with limited allochthonous inputs, contemporaneous primary production may be not necessary for high secondary production and insect emergence. Instead, consumers can develop from consumption of biomass derived from past autochthonous primary production. This suggests that primary production and consumer dynamics can be partially decoupled in time in systems that depend on internal production.


Inland Waters ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 13-28 ◽  
Author(s):  
Amanda R. McCormick ◽  
Joseph S. Phillips ◽  
Jamieson C. Botsch ◽  
Anthony R. Ives

2020 ◽  
Vol 8 ◽  
Author(s):  
Philip A. E. Pogge von Strandmann ◽  
Kevin W. Burton ◽  
Sophie Opfergelt ◽  
Eydís S. Eiríksdóttir ◽  
Melissa J. Murphy ◽  
...  

2019 ◽  
Vol 98 ◽  
pp. 07023
Author(s):  
Finnbogi Óskarsson

The origin of the warm groundwater which feeds Lake Mývatn is unknown, but it has been affected by volcanic episodes as well as geothermal activity and utilisation. In this contribution stable isotopes of hydrogen (2H), oxygen (18O), sulphur (34S), chlorine (37Cl) and strontium (86Sr and 87Sr) in 20 groundwater and effluent samples from the Lake Mývatn area are used to constrain the origin of the warm groundwater. The results suggest that the warm groundwater is partly formed by mixing with geothermal effluent water and partly by mixing with geothermal steam.


2019 ◽  
Author(s):  
Yasiri Nunez ◽  
◽  
Kevin M. Theissen ◽  
Jeff Thole ◽  
Reid Swanson ◽  
...  
Keyword(s):  

Hydrobiologia ◽  
2018 ◽  
Vol 816 (1) ◽  
pp. 243-254 ◽  
Author(s):  
Mireia Bartrons ◽  
Ignasi Arranz ◽  
Miguel Cañedo-Argüelles ◽  
Serena Sgarzi ◽  
Torben L. Lauridsen ◽  
...  

Polar Biology ◽  
2017 ◽  
Vol 41 (8) ◽  
pp. 1547-1554 ◽  
Author(s):  
Jose A. Sanchez-Ruiz ◽  
Joseph S. Phillips ◽  
Anthony R. Ives ◽  
Claudio Gratton

Ecosphere ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. e01659 ◽  
Author(s):  
Kyle C. Webert ◽  
Cristina M. Herren ◽  
Árni Einarsson ◽  
Mireia Bartrons ◽  
Ulf Hauptfleisch ◽  
...  
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