Patrick Principle(s)

My father “influenced me to realize that the most important things in life [are] to understand the natural world and . . . to be kind to my fellow man, even though I might not understand them.”
   ~ Ruth Patrick, Hometown Legends:  Ruth Patrick, WHYY TV, aired October 30, 2004

 Perhaps I’m impressed by trivial connections that I consider insights and the one at the center of this post might be one of those.  Even if that’s true, Ruth Patrick is someone we should all get to know.

Over the past several weeks, I have been reading a couple of informative and entertaining accounts of the Permian extinction, that mother of all mass extinctions – Gorgon:  Paleontology, Obsession, and the Greatest Catastrophe in Earth’s History by Peter D. Ward (2004) and Extinction:  How Life on Earth Nearly Ended 250 Million Years Ago by Douglas H. Erwin (2006).  Ward and Erwin, both practicing paleontologists, certainly know how to write for a popular audience.  Ward’s account focuses on terrestrial extinction, particularly as it is recorded in the bleak and beautiful Karoo region in South Africa.  His is a decidedly more personal story (sometimes too much so) as he plays the starring role; on occasion, it crosses into the “tell all” territory (one wonders whether he has been able to continue to work with at least one of his colleagues, Roger Smith, after the way Smith is characterized in the book).  Erwin’s volume offers a more deliberate explanation of the Permian extinction and a well-structured exploration of the various hypotheses about its causes.  It, too, ventures into the first person at times when it takes the reader into the field.  Good videos of talks on this subject delivered by both authors are available on the web.  There’s Ward’s TED talk and Erwin’s talk at the Santa Fe Institute.

I found one aspect of the aftermath of the Permian mass extinction that both Ward and Erwin describe to be particularly surprising.  Yes, the Permian extinction cut a devastating swathe through the ranks of plant and animal taxa.  For example, according to Erwin, the two pulses of Permian extinction, separated by some 10 million years, eliminated at least 90 percent of all marine species.  I suppose I’d previously assumed (if I'd actually had any coherent thoughts about it) that a devastated, lifeless environment ensued and endured for thousands, hundred of thousands, or perhaps millions of years.  But that’s not necessarily the case.

Erwin opens his book in Utah, where “the Triassic is laid out for anyone who cares to look, although few do,” apparently because the fossils are either scarce or boringly the same.  (p. 1)  Later, he describes formations that were laid down during the early stages of recovery from the Permian extinction, formations that essentially are “pavements built of thousands upon thousands of specimens of the characteristic Early Triassic scallop Claraia. . . . Despite the incredible abundance of some species, the total number of Early Triassic species is a tiny fraction of those alive only a few million years earlier or later.”  (p. 200-221)

Along the same lines is this observation by Peter Ward about fossil hunting in the Karoo,

For reasons still unfathomable, the lowest Triassic strata above the mass-extinction boundary are composed of red beds packed with fossils.  Almost all belong to a single species of mammal-like reptile – Lystrosaurus.  After the hard work of finding the very rare fossils in the youngest Permian beds, the fossils in these oldest Triassic beds were indeed a holiday.  There is an irony and mystery to this.  These beds were deposited soon after the mass extinction.  Yet the fossils – at least of this one species – are very common.  (p. 145)

(The fossil skeleton of the pig-sized Lystrosaurus hedini is shown above in a photograph by Rama, downloaded from Wikimedia and reproduced under the Creative Commons Attribution-Share Alike 2.0 France license.)

Ward suggests that perhaps this simply reflects that, in the post extinction period, conditions conducive to fossil formation were more prevalent.  But, significantly, he adds, “Or perhaps there were more animals – at least of this one single species.”  (p. 145)

In the midst of my immersion in the Permian extinction and its consequences, I happened to come across obituaries for botanist and ecologist Ruth Patrick (1907 – 2013), who died on September 23, 2013 (Julie Zausmer, Ruth Patrick, Ecology Pioneer, Dies at 105, The Washington Post, September 23, 2013; William Dicke, Ruth Patrick, a Pioneer in Science and Pollution Control Efforts, is Dead at 105, The New York Times, September 23, 2013.)

What a marvelous human being she was.  I am quite taken by her life story and scientific endeavors for many reasons.  One of them is the link, at least I think it’s a link or a connecting insight between Patrick’s signal contribution to science – the so-called Patrick Principle – and the aspect of the aftermath of the Permian mass extinction that I’ve just described – loss of taxonomic diversity.  In addition, a side of her life that I found particularly compelling was her relationship with her father.  I consider both of these topics below.

(This picture of Ruth Patrick is reproduced with the permission of the Ruth Patrick Science Education Center at The University of South Carolina Aiken.)

Patrick was a pioneer in many ways, not only as a woman breaking into the male-dominated scientific ranks in the 1930s and 1940s (talk about surviving in a hostile environment), but also as a botanist central to the modern development of the science of limnology (study of the ecology of rivers).

In 1934, largely because she was a woman and the Depression was in full swing, Patrick who was about to earn her doctorate from the University of Virginia could only find volunteer work at the Academy of Natural Sciences in Philadelphia.  In recounting her work experiences in science and at the Academy, Patrick was very matter of fact about the sex discrimination she encountered.  Not until 1945 did the Academy begin to pay her a salary.  In time, she established a department of limnology in the Academy, taught for many years at the University of Pennsylvania, published over 200 articles and several books, was elected to the National Academy of Sciences, and received the National Medal of Science, as well as the John and Alice Tyler Ecology Award.

She was a force to be reckoned with.  Her husband, entomologist Charles Hodge, once described his marriage as “like being married to the tail of a comet.”  It is clear in the 2004 WHYY TV show devoted to Patrick that, even at age 96, she remained youthfully passionate about science and about the role of women in the sciences.

Her key scientific contributions came from her study of diatoms (single celled algae), particularly her analysis of the relationship between water quality and the diversity of diatom communities in rivers.

(Photo on left is of Amphiprora alata (95 microns or 0.095 mm long); on right is Achnanthes frigida (no length given).  These images are from the Smithsonian Environmental Research Center's Phytoplankton Guide to the Chesapeake Bay and Other Regions.  They are used with permission of the Smithsonian.)

I do not pretend to know Patrick's work, reliant as I largely am on others’ descriptions, but it is widely asserted that Patrick was instrumental in a major shift in how water quality is analyzed, broadening it from a narrow focus on the presence of pollutants in the water to an appraisal of the diversity of the communities of organisms living in the water.  Her work on water pollution helped lead to enactment of the Clean Water Act.

Her conclusion that the diversity of species living within a fluvial environment reflects the overall health of this water is sufficiently profound that biologist Thomas E. Lovejoy has named it the Patrick Principle.  He writes,

In 1948 a line of research led by Ruth Patrick on freshwater communities in the United States (principally rivers) demonstrated that the number and variety of species reflected the natural physics and chemistry of a river as well as the stresses to which it was subject (e.g., pollution).  This work, which deserves to be recognised as the Patrick Principle, can be generalized to all kinds of biological communities, i.e., marine and terrestrial as well as freshwater.

Put differently, environmental stresses are all defined as problems because they affect living systems (not just humans).  So whether pollution, habitat destruction or climate change, they all impinge on biological diversity.  Consequently biological diversity is the ultimate integrator of environment change.  When that change is sufficiently intensive and extensive it leads to species extinction.  That, together with the scale and rate of the various kinds of environment change, conspires to create the biological diversity crisis.  (Biodiversity:  Threats and Challenges, in Biodiversity, Sustainability and Human Communities:  Protecting Beyond the Protected, edited by Tim O’Riordan and Susanne Stoll-Kleemann, 2002, p. 34. )

If I interpret the Patrick Principle properly, it’s that in times of environmental stress the diversity of the species that remain within the community is changed and impoverished.  Indeed, it’s possible that some of those that survive the stresses actually thrive.  Perhaps in the three decades since we were first introduced to the terms biological diversity and biodiversity we’ve become so familiar with them and their implications for our understanding of the environment that the Patrick Principle seems like a truism.  It shouldn’t be.

And then, at some point, I made what probably seems to be the pretty obvious connection between the aftermath of the Permian extinction and the Patrick Principle.  The consequences of environmental degradation documented in American rivers and streams by Patrick (the lessened diversity of life, not necessarily its absence) played out in the lowest Triassic – fewer species but, in some places, an abundance of individuals, like the Early Triassic scallop Claraia or the herbivore Lystrosaurus hedini.

Maybe it’s a prosaic insight, but it’s what I had.

There’s another aspect of Patrick’s life that I found particularly appealing – her unbridled admiration of her father.  (I suppose as a father, I’m inclined to make a big deal out of this.)  Her father, a lawyer, not only instilled a love of nature in Ruth and her sister, but also encouraged them to reject the traditional roles that females were expected to play in society, much to consternation of his wife.

Ruth recounted that her father “loved the natural world.”  (This and all subsequent quotations are from the WHYY show Hometown Legends:  Ruth Patrick cited earlier.)

Every Sunday afternoon, from the time I was five to about twelve, I would take a walk with him.  And we would always go to some woods.  Typically I would carry a basket.  And when I was little, of course I collected everything, worms, mushrooms, plants, and rocks, and everything and then we’d go home.  And my sister and I would have our milk and crackers, and, while we were eating and afterwards, Father would identify what we had in our baskets.  And, of course, we felt very proud if we could identify them and tell him what they were.

That her scientific pursuits had her mucking around in fields and streams did not sit well with her mother.  Even as her mother “felt girls should be in the home, not out in the fields, so to speak,” Patrick turned to her father and followed his advice, embracing science, academic pursuits, and the field.  In that day and age, she noted, “Ordinarily, [a] nice, healthy girl, just shouldn’t want to get a Ph.D.”  But, her father “believed that women could accomplish a good deal.  He used to say to me, ‘With your spare time, read, improve your mind.  You can hire people to wash dishes.’”

And, so, into her old age, Ruth Patrick remained focused on “trying to understand the natural world and to understand why we have the assortment of species we do have operating in our ecosystems and how can we protect them, how can we keep it happening.”