The annual tweet roundup for Ecology (EES-152)

Lots of fun was had in EES-152 (Ecology) at Lehigh University this fall. Below is the annual student tweet roundup…..

Crazy as a loon

Last week while canoeing on a lakes in the Nancy Lake Area of Alaska (about 90 minutes north of Anchorage), we saw quite a few loons (Gavia immer). Common inhabitants of northern lakes, their vocalizations are one of my favorite sounds. On this particular trip we were lucky enough to observe an individual that took unusual interest in us, swimming close to the canoe and even swimming under it multiple times. Loons are impressive divers, as this is how they obtain their food, but had never seen one swimming underwater before. Below are some pictures and two sound recordings highlighting two of their distinct calls.


Common loon in the Nancy Lake Area of Alaska. July 2018.


Swimming underwater alongside the canoe. July 2018.


Another image of the loon swimming underwater alongside the canoe. July 2018.

Tweet roundup. Ecology (EES-152), Fall Semester 2017.

Some of my favorite course-related tweets in Fall 2017…. another semester of fun!

Observing the observer

It is starting to feel like fall, although there are not many colors in the trees yet.

The colors were vivid on the day pictured in the painting below, and I fondly remember a really great hike through a hemlock-dominated ravine as part of this camping trip a few years ago. The painting was an attempt to capture a moment that I spent watching my daughter as she sketched in her notebook.


Observing the Observer. Oil on Canvas. Finished May 2017.

State of the Lehigh Experimental Forest, 2017

20170911_150231General ecology (EES-152) students have finished resurveying a portion of the Lehigh Experimental Forest, assessing changes in species mortality and recruitment since 2013. A total of 1174 trees were inventoried and measured from across the forest the last two years, representing more than 1/2 of all trees originally tagged in 2013. In the four  years since 2013, 167 of these 1174 trees have died (~14%) and only eleven new trees have established in the study area (<1%).  Data for the dominant tree species are shown in the plot below.

LUEF 2017

Abundance, mortality, recruitment, and the net percentage change of tree/shrub species in the Lehigh University Experimental Forest, 2013-2017. Relative frequency data are from 2013 (M. Spicer, MS thesis 2014) and indicate the percent of each species present (based on a total of 1174 trees). Total mortality and recruitment for each species with greater than 10 individuals are shown as percentages. Species are arranged from those undergoing substantial declines in abundance at the top to those that have increased in abundance on the bottom.


We will use these data to discuss processes controlling forest dynamics as the semester progresses.  However, for now, students should answer the following questions:

  1. What factors might have caused the differences in mortality among species?
  2. Develop a hypothesis to explain the lack of recruitment for most tree/shrub species. Then do some research on the two tree species that have successfully recruited and those species that have not. Are there species traits that are common to successful and unsuccessful recruiters? Are these traits consistent (or inconsistent) with what you might predict from your hypothesis?
  3. What does the pattern of mortality and recruitment suggest about the future of the Lehigh Experimental Forest? Assuming the rates of total tree recruitment and mortality are representative of future years, when will there be less than 100 trees in this forest?  In 2013, there were ~2000 trees in the forest so you can use that as your starting number. Show your work and describe how you arrived at your estimate.  Do you think this scenario is likely?  Why or why not?

The Tangled Bank Gets A Sign!

The Tangled Bank, an ecologically and historically interesting spot on the Lehigh University campus (see here for details), gets some well-deserved recognition with a sign!

Invasion confirmed. Water lettuce and water hyacinth overwintering in Pennsylvania.

Last September, two invasive aquatic plants, water lettuce (Pistia stratiotes) and water hyacinth (Eichhornia crassipes), were discovered in the Lehigh Canal in Bethlehem PA.  Both species are floating plants, like duckweeds but much larger, and they often grow in dense mats in tropical and subtropical regions. Although this was the first confirmed occurrence in natural habitat within Pennsylvania, both species are sensitive to freezing temperatures so they have not not been regarded as major threats in the Northeast. A description of the discovery of these populations and some background on the species, including a discussion of recent work suggesting that the overwintering potential may be greater than previously thought, can be found in my post from last year (New invaders in the Lehigh Valley? Or Just Summer Visitors?).

The discovery last year prompted several questions. In particular, are these populations really persisting from year-to-year and therefore surviving freezing temperatures? I suspected that they were introduced last summer from someone’s pond and that they would not survive the winter. However, the winter was mild and the recent discovery of some overwintering populations in the lower Great Lakes gave me pause. I road my bike along the canal towpath last week to have a look.

I was wrong. Both species have overwintered. A harbinger of things to come?  Below are some pictures, and I’ll update this post with more later in the summer.


Water lettuce survived the Pennsylvania winter in the Lehigh Canal. 10 July 2017.


Water hyacinth also survived the Pennsylvania winter in the Lehigh Canal. 10 July 2017.


Larger clump of water lettuce in the middle of the canal. 10 July 2017.


Only a little bigger than the duckweed, you can see the light-green colored water lettuce in this image. Given the small size, I suspect it came back from seed. 10 July 2017.

What’s in a name? Something (completely different) to be said about taxonomic nomenclature

A fun post on inspiration for species names….in testate amoebae!

From inside the shell

By Edward A. D. Mitchell,

Laboratory of Soil Biodiversity, University of Neuchâtel, Switzerland

With the advent of high throughput sequencing, estimates of global diversity are being totally revised.  For us protistologists – arguably much more importantly – so is the picture of how diversity is distributed among the different branches of the tree of life. The image that emerges is one that shows a huge unknown diversity among protists, at all levels, from major groups (i.e. “environmental clades”) and within known groups (i.e. from more or less divergent groups to complexes of cryptic and pseudo-cryptic species). This is fascinating and to say the least mind-boggling and a much welcome development for making a case about the need to study protists more intensively. It is indeed impossible today to ignore this diversity and the many functional roles that protists play in all ecosystems.

But this unknown diversity also calls for a…

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