Late Glacial and Holocene Palaeolake History of the Última Esperanza Region of Southern Patagonia

We undertook multi-proxy analyses on two sediment cores from Lago Pato, a small lake basin at 51°S topographically separated from Lago del Toro in Torres del Paine (TdP), to provide insights into glacier dynamics and lake-level change in the TdP and Última Esperanza region over the last ∼30,000 cal a BP (30 ka). Lago Pato is situated in a region overridden by the Southern Patagonian Ice Field during the Last Glacial and in a transitional climatic zone of Southern Patagonia sensitive to seasonal- to millennial-scale changes in the Southern Hemisphere Westerly Winds (SWW). Results show that a deep ice-dammed and enlarged palaeolake encompassed Lago del Toro and Lago Pato c. 30–20 ka after the ice had retreated from local-Last Glacial Maximum (l-LGM) limits at c. 48–34 ka and during the build-up to the global-Last Glacial Maximum (g-LGM), c. 26–19 ka. Gaps in both sediment records between c. 20–13.4 ka and c. 20–10 ka suggest hiatuses in sediment accumulation during the g-LGM and Antarctic Cold Reversal (ACR) readvances and/or removal by lake lowering or flushing during the Late Glacial–early Holocene. The palaeolake level dropped from >100 m a.s.l. to ∼40–50 m a.s.l. towards the end of the ACR c. 13.4–13.0 ka, creating a shallower glaciolacustrine environment dammed by an ice tongue in the Estancia Puerto Consuelo–Última Esperanza fjord. Further lowering of the enlarged palaeolake level occurred when the ice thinned to <40 m a.s.l., eventually isolating Lago Pato from Lago del Toro and glaciogenic sediment input at c. 11.7 ka. After isolation, the ecology and water levels in Lago Pato became sensitive to regional climate shifts. The shallow, stable, and highly anoxic environment that developed after c. 11.7 ka is associated with weaker (or poleward shifted) SWW at 51°S and was replaced at c. 10 ka by an increasingly productive shallow-littoral lake with a variable lake-level and periodic shifts in anoxic-oxic bottom water conditions and ratios of benthic-planktonic diatoms. A more open Nothofagus forest, established at c. 8.6–7.5 ka, and more arid conditions c. 7.5–5.7 cal ka BP are linked to another phase of weaker (or poleward shifted) SWW at 51°S. More persistently wet conditions from c. 5.7 ka, with extensive closed Nothofagus forests and planktonic diatoms dominant, are associated with stronger (or equatorward shifted) SWW over 51°S. The abrupt return of benthic-to-tychoplanktonic diatoms after c. 3 ka reflects enhanced SWW at 51°S. Increasingly stable lacustrine and littoral wetland conditions established in the last ∼500 years reflect weaker SWW and lasted until recent decades

The Impact of Conservation Management on the Community Composition of Multiple Organism Groups in Eutrophic Interconnected Man-Made Ponds.

Ponds throughout the world are subjected to a variety of management measures for purposes of biodiversity conservation. Current conservation efforts typically comprise a combination of multiple measures that directly and indirectly impact a wide range of organism groups. Knowledge of the relative impact of individual measures on different taxonomic groups is important for the development of effective conservation programs. We conducted a field study of 28 man-made ponds, representing four management types differing in the frequency of periodic pond drainage and the intensity of fish stock management. We disentangled the relative importance of direct and indirect effects of pond management measures on the community composition of phytoplankton, zooplankton, aquatic macro-invertebrates, submerged and emergent vascular plants. With the exception of phytoplankton, pond management had strong effects on the community composition of all investigated biota. Whether management affected communities directly or indirectly through its impact on fish communities or local environmental conditions in the pond varied between organism groups. Overall, the impact of pond drainage regime and fish community characteristics on the community composition of target organism groups were more important than local environmental conditions. The majority of taxa were negatively associated with fish density, whereas multiple emergent plant species and several taxa of aquatic macro-invertebrates were positively affected by increased drainage frequency. The effects of fish community and drainage tended to be largely independent. The present study indicates that pond drainage is an important element for biodiversity conservation in eutrophicated shallow and interconnected man-made ponds

Data from: The impact of conservation management on the community composition of multiple organism groups in eutrophic interconnected man-made ponds

Ponds throughout the world are subjected to a variety of management measures for purposes of biodiversity conservation. Current conservation efforts typically comprise a combination of multiple measures that directly and indirectly impact a wide range of organism groups. Knowledge of the relative impact of individual measures on different taxonomic groups is important for the development of effective conservation programs. We conducted a field study of 28 man-made ponds, representing four management types differing in the frequency of periodic pond drainage and the intensity of fish stock management. We disentangled the relative importance of direct and indirect effects of pond management measures on the community composition of phytoplankton, zooplankton, aquatic macro-invertebrates, submerged and emergent vascular plants. With the exception of phytoplankton, pond management had strong effects on the community composition of all investigated biota. Whether management affected communities directly or indirectly through its impact on fish communities or local environmental conditions in the pond varied between organism groups. Overall, the impact of pond drainage regime and fish community characteristics on the community composition of target organism groups were more important than local environmental conditions. The majority of taxa were negatively associated with fish density, whereas multiple emergent plant species and several taxa of aquatic macro-invertebrates were positively affected by increased drainage frequency. The effects of fish community and drainage tended to be largely independent. The present study indicates that pond drainage is an important element for biodiversity conservation in eutrophicated shallow and interconnected man-made ponds

data of fish ponds in Belgium

This dataset contains data of multiple aquatic biota and major environmental variables of fish ponds in Belgium

Conceptual model representing the potential direct and indirect ways through which pond management can affect aquatic communities.

<p>Management may determine fish community characteristics (1), which may affect other organism groups directly through the associated predation regime (2a) or indirectly via an alteration of the pond environment (2b+3). Management may also affect aquatic communities by altering local environmental pond conditions (4+3). In addition, management can also determine the pond drainage regime (5), which in its turn may have direct effects on aquatic communities (6a), or indirect effects through its impact on the fish community (6b+2a or 6b+2b+3) or the pond environment (6c+3). Management may also have unique effects independently of fish, drainage regime and the measured environmental variables (7).</p

Results of RDA analyses.

<p>^a The percentage of explained variation (i.e. marginal effects).</p><p>^b The significance level</p><p>'*' p <0.05</p><p>'**' p <0.01; 'ns' not significant.</p><p>^c Significant environmental variables that were selected by the forward selection procedure.</p><p>RDA analyses separately testing for effect of pond management type (MAN), fish community composition (FISH), local environment variables (ENV) and frequency of pond drainage (DRAIN) on the community composition of each of the studied target organism groups.</p

Description of the pond management types in relation to fish stock management and frequency of periodic pond drainage.

<p>These management types are currently applied in the region for purposes of biodiversity conservation.</p

Stacked bars showing the results of variation partitioning analyses on community composition of phytoplankton (PP), submerged and floating vegetation (SUBM), emergent vegetation (EMERG), aquatic macro-invertebrates (MI), mollusks (MOLL), Hemipterans (HEMI), and zooplankton (ZP).

<p>The left-hand bars show compositional variation uniquely explained by fish (F|ED), pond environmental variables (E|FD) and pond drainage (D|FE), as well as the fraction of variation that is commonly explained by fish and environment (F∩E), drainage and fish (D∩F), drainage and environment (D∩E) and by drainage, fish and environment (D∩F∩E). Right-hand bars show the proportion of variation that is commonly explained by fish, pond environment and drainage independently from management (FED|M), the proportion of variation commonly explained by pond management, fish, pond environment and drainage (M∩FED), and the proportion of variation that is uniquely explained by pond management (M|FED). Proportions of variation that are significantly explained are indicated with * (P<0.05). Note that the significance of the fractions F∩E, D∩F, D∩E, D∩F∩E and M∩FED cannot be tested.</p

Ordination plots of Principal Component Analyses (PCA).

<p>(A) PCA plot on fish biomass composition and (B) a standardized PCA plot on pond environment variables. Black triangles represent the centroids of the pond management types and were plotted as supplementary variables, in order not to influence the ordination. Numbers behind the fish species names indicate different size classes (1: < 10 cm, 2: >10 cm and 3: >20 cm; except for <i>L</i>. <i>gibbosus</i>, <i>P</i>. <i>parva</i> where 1: < 7cm and 2: > 7cm; for <i>G</i>. <i>gobio</i>, <i>P</i>. <i>pungitius</i> and <i>R</i>. <i>sericeus</i> no differentiation in size classes was made). <i>A</i>. <i>nebusolus</i> = <i>Ameiurus nebulosus</i>, <i>C</i>. <i>gibelio</i> = <i>Carassius gibelio</i>, <i>C</i>. <i>carpio</i> = <i>Cyprinus carpio</i>, <i>G</i>. <i>gobio</i> = <i>Gobio gobio</i>, <i>L</i>. <i>gibbosus</i> = <i>Lepomis gibbosus</i>, <i>L</i>. <i>idus</i> = <i>Leuciscus idus</i>, <i>P</i>. <i>fluviatilis</i> = <i>Perca fluviatilis</i>, <i>P</i>. <i>parva</i> = <i>Pseudorasbora parva</i>, <i>P</i>. <i>pungitius</i> = <i>Pungitius pungitius</i>, <i>R</i>. <i>sericeus</i> = <i>Rhodeus sericeus</i>, <i>R</i>. <i>rutilus</i> = <i>Rutilus rutilus</i>, <i>S</i>. <i>erythrophthalmus</i> = <i>Scardinius erythrophthalmus</i>, <i>T</i>. <i>tinca</i> = <i>Tinca tinca</i>.</p

Overview of a part of "Vijvergebied Midden-Limburg" with the selected ponds representing the different management types.

<p>See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072538#tab1" target="_blank">Table 1</a> for a detailed description of each pond management type. Note that one NF-pond, situated approximately 2 kilometers east of the depicted ponds, is not drawn on the map.</p