Category Archives: Uncategorized
16 January 2017
Today was a very long day of travel. We were supposed to fly from Manizales to Bogota, pick up the lake coring equipment that we left there, and then drive about 3.5 hours northeast to the city of Sogamoso. However, after spending a couple hours waiting for our plane to arrive, our flight was cancelled. The weather didn’t seem particularly bad, but the Manizales airport closed. Apparently it closes about 50% of the time. Perhaps it was ash from the volcano?
The airline provided a bus to transport passengers to Pereira, the nearest place with an airport, and we were rebooked on a flight to Bogota from there. Having seen the public bus passing cars on the winding road up the mountains from Manizales a couple days ago, I was a bit nervous about the bus trip. However, the ride was uneventful and we arrived in Pereira in about an hour and a half. We observed endless coffee fields on the drive, and given that Pereira is only at about 1000 meters in elevation, the temperature was considerably warmer when we arrived at the airport.
We arrived in Bogota about 5 hours later than we had scheduled. Unfortunately, the truck that we had reserved at the Bogota airport was not available because it was wrecked in a crash by the previous renter. I can’t say that I was surprised. So we rented an SUV instead, a Toyota Fortuner which I had never heard of, and once we loaded the coring equipment there was very little room left for passengers. However, we all squeezed in and headed out into the rush hour traffic of Bogota. Lots of public diesel buses made for pretty bad pollution. However, we made it to Sogamoso in reasonable time, stopping along the way for a tamal and flatbread for dinner, and arrived at our hostel a little after 10 pm – about 14 hours of traveling. I was tired, but excited to see a new paramo ecosystem.
Back in June an alligator was found in the Lehigh Canal. Apparently it wasn’t the first one found in the broader Lehigh Valley.
But perhaps just as surprising are a couple of potentially new plant arrivals. Or are they just summer visitors? Last week I noticed sizable populations of two aquatic plant species, water lettuce (Pistia stratiotes) and water hyacinth (Eichhornia crassipes), in the canal at Sand Island in Bethlehem. Both of these species float unattached on the water surface, like the more common duckweeds, and they often grow in dense mats that make fishing and boating difficult, crowd out other plant species, and alter water chemistry and light penetration. To my knowledge, neither species is confirmed to occur naturalized in Pennsylvania but it is not uncommon to see them cultivated in backyard ponds (USDA Plants: water hyacinth, water lettuce).
The populations of water lettuce and water hyacinth in the Lehigh Canal consist of scattered colonies extending from about the Hill-to-Hill Bridge (Route 378) east past the New Street Bridge (Fahy Bridge), to about the point where the Sand Island Trail meets the towpath (D&L Trail). The total distance is about a half mile. The water lettuce appears to cover a slightly greater distance than the water hyacinth, and the plants are generally smaller in height as you head east (downstream) from the Main Street Bridge.
Water lettuce and water hyacinth are tropical or subtropical in origin. The two species have dramatically expanded their range in warmer regions in recent years, where they have cause considerable ecological and recreational impacts. However, given that both species are sensitive to freezing temperatures, they have not not been regarded as major threats in the Northeast. However, some uncertainty about this assumption has emerged in the last several years. For example, a few years ago populations were found in the lower Great Lakes (Adebayo et al. 2010), and resurveys found both species in three subsequent years (Maclsaac et al. 2016), raising concerns about the potential for the establishment of persistent populations in more northerly locations. Although freezing typically kills individuals of both species they can produce seeds that survive cold temperatures; in fact, water lettuce seeds can still be viable after a few weeks in solid ice (Pieterse et al. 1981). Maclsaac et al. (2016) suggested that the two species likely persist in the lower Great Lakes due to annual reintroductions by humans (both species are sold for ponds/aquariums), but also noted that at least in the case of water hyacinth, seasonal regeneration from viable seeds may be occurring.
For background, the Lehigh Canal was built in 1827 to transport anthracite coal from the upper Lehigh Valley, and it remained in operation until the early 1940s. Heavy transportation and industrial activity along the canal and river corridor, as well the development of the surrounding Allentown-Bethlehem-Easton region led to numerous environmental problems, including pollution, habitat degradation, the spread of invasive species, and eutrophication of the canal. However, the towpath along the canal is now a natural-area corridor and the old towpath is a great place to bike, run, hike, fish, bird, and observe nature from within the urban and suburban matrix of the Lehigh Valley. Near Sand Island in Bethlehem, the canal itself gets pretty green by mid-summer, as the slow-moving water warms and algae proliferate. Invasive eurasian water milfoil (Myriophyllum spicatum) and curly-leaf pondweed (Potamogeton crispus) are common submerged plants within the canal, and provide a favorable substrate for filamentous algae. The habitat is ideal for water lettuce and water hyacinth, except for the fact that it freezes in the winter.
Have these species been in the canal in previous summers? Are these populations persisting, or did this expansion occur just this year? Perhaps the two species came into the canal with the pet alligator 🙂 Although this was the first time I noticed the two floating species, I don’t frequent this particular area of the towpath often. Will they reemerge next summer? Are they producing viable seed? Lots of questions, and certainly something to watch. The observations have been submitted to iMap Invasives, a database of invasive species.
Of course, floating plants are also very good at moving. Maybe not as fast as an alligator, but fast enough for me to watch a cluster of water lettuce floating down the canal. Perhaps on its way to Easton?
Adebayo, A., E. Briski, O. Kalaci, M. Hernandez, S. Ghabooli, B. Beric, F. Chan, A. Zhan, E. Fifield, T. Leadley, and H. MacIsaac. 2011. Water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) in the Great Lakes: playing with fire? Aquatic Invasions 6: 91-96. DOI 10.3391/ai.2011.6.1.11.
MacIsaac, H.J., A.P. Eyraud, B. Beric, and S. Ghabooli. 2016. Can tropical macrophytes establish in the Laurentian Great Lakes? Hydrobiologia 767: 165-174. doi:10.1007/s10750-015-2491-y
Pieterse, A. H., L. Delange, and L. Verhagen. 1981. A study on certain aspects of seed germination and growth of Pistia stratiotes L., Acta Botanica Neerlandica 30: 47–57. doi:10.1111/j.1438-8677.1981.tb00386.x
Great post on the iSTAR blog by Daniel Puppe… on the role of testate amoebae in silicon cycling within terrestrial ecosystems. Testate amoebae in forest ecosystems convert 17 kg – 80 kg of soluble silicon into the mineral phase of silica in a year! Perhaps exceeding the trees!
Contributed by Daniel Puppe
Silicon is the second most common element in the Earth’s crust (after oxygen) and the seventh most abundant element in the universe. That means we can find silicon almost everywhere. Silicon plays a pivotal role in diverse living organisms comprising pro- and eukaryotes accumulating biogenic silicon in various siliceous structures (= biosilicification) – like idiosomic testate amoeba shells. In soils of terrestrial ecosystems we can find a lot of biogenic silicon forming different silicon pools. These pools can be separated into zoogenic, phytogenic, microbial and protistic ones (Fig. 1).
While scientific research has been focused especially on the phytogenic silicon pool (represented by so-called phytoliths), little is known about zoogenic, microbial and protistic silicon pools. The protistic silicon pool in soils comprises mainly terrestrial diatoms and idiosomic testate amoebae (some testates are shown in…
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Sampling testate amoebae in a tropical peatland. A recent paper in Microbial Ecology by Swindles et al. suggests that testate amoebae have good potential as hydrological indicators in tropical peatlands.
Testate amoebae have been successfully used as indicators of past changes in peatland hydrology, particularly ombrotrophic (i.e., nutrients derived exclusively from precipitation) peatlands of north-temperate and boreal regions. Over the past couple decades, many ecological studies of testate amoebae have been performed in these northern bogs, allowing empirical relationships between community composition and surface moisture to be described. Because the shells of testate amoebae preserve well in the acidic and anaerobic environment of bogs, these modern relationships have been used to infer past changes in the relative wetness of the bog surface from the composition of subfossil communities. Much recent work has focused on the validation and interpretation of testate amoeba paleohydrological records from bogs, and their application to pressing global change questions.
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The Pymatuning wetlanders discussed wetland restoration this morning, including an examination of the Florida Everglades Project, which is the largest wetland restoration ever attempted. We discussed the history of environmental degradation in South Florida and how it altered the hydrology and biogeochemistry of this unique wetland complex. The students were happy to apply their knowledge of Phosphorus cycling toward understanding some of the problems and challenges that the restoration effort is attempting to fix.
We had a short break, during which the students finished mounting a few labels on their plant collections and collectively cleaned the wet lab of peat, mud, dead macroinvertebrates, and various other byproducts of our recent explorations. We then briefly discussed treatment wetlands, highlighting the use of these created wetlands to treat things like municipal wastewater, non-point source pollution, and acid mine drainage. I then provided a brief overview of the course and its structure, highlighting what this hard-working group students has accomplished in only three weeks. Then we had one last bit of fun exploring some of the wetlands in the littoral zone of Pymatuning Reservoir via canoe. The students used the rest of the afternoon to study for tomorrow’s final exam.
Contributed by Matt Amesbury
The use of testate amoebae as a proxy for past changes in the hydrological status of peatlands has become ever more popular over the past two decades. Studies have been carried out over an increasing geographical range covering most major areas of northern hemisphere peatlands as well as in Patagonia and New Zealand amongst other places south of the equator. Despite this pushing of “amoebal” boundaries, there is one place you might certainly expect to be able to rule out moss-based testate studies: Antarctica.
Only a tiny 0.3% of the Antarctic continent is ice free, yet in parts of this seemingly minute slither, the climate is just about amenable enough to have permitted the formation of deep moss banks; accumulations of moss that grow a few millimetres each year and are then frozen stiff over the winter months only to thaw out in the…
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Opening the Pandora box of community ecology – The value of long-term data sets and collaborative research
Community ecologists study how communities of plants, animals and other organisms vary in space and time, how they interact and what controls these patterns. To do this they usually either observe (more or less) natural communities or conduct experimental manipulation in the field (in situ experiments) or in controlled conditions (mesocosms, microcosms). Observational studies of natural communities have the longest history and have contributed to major (and often controversial) theories in ecology such as the intermediate disturbance hypothesis (IDH). Starting with the more easily studies taxonomic groups such as vascular plants observational studies of natural communities have expanded to covering numerous taxonomic groups, including microbes and of course testate amoebae.
In order to describe the ecological preferences of species numerous plots need to be studied, typically in the range of 50-100 or more if possible. And even so, most studies end up with a fair number of rare species, which…
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Today marks the first day of summer research! Bob Mason, my undergraduate research assistant, and I went up to the LUEF today to start re-establishing the boundaries of the forest. We also cored 10 trees that fell last fall during the intense winds and rain of Hurricane Sandy in October of 2012.
While traipsing about in the forest, we found a mislabeled tree from last semester–definitely a maple, but not a sugar maple, as it had been labeled under. It looks like it might be a sycamore maple (Acer pseudoplatanus), with its serrated edges and small, acute-angled semaras. If so, that’s another invasive species to look out for in the LUEF.