An Analysis of Mackie 2007 (through the lens of Gen Alpha)

 Hey chat, I welcome you to my yap sesh about bivalves (clams, mussels, etc.) and Mackie’s book about some of them. Please excuse the slang for real for real, I need a way to keep y’all engaged because the topic I’m writing on is traditionally rather boring and not skibidi sigma. To start, Corbicula and Sphaeriidae are two types of small clams that live in freshwater habitats like ponds, rivers, lakes, etc. There is a third group, Unionidae, which is a group of mussels (not “clams”) that also lives in freshwater. In North America, Unionidae and Sphaeriidae are native. Both groups play an essential role in filter feeding and nutrient cycling. Without them, freshwater habitats would be more stagnant, murky, and overrun with algae suffocating most life. Basically, native bivalves are unpaid janitors. 

Corbicula, on the other hand, is invasive and was introduced to the United States in the 1920s–1930s. In terms of using up resources, Corbicula solos, no diff, straining native bivalve populations. Like the skibidi toilets against the cameramen and speakerheads. Corbicula’s invasion in North America is causing Unionidae and Sphaeriid populations to sharply decline, even faster than the amount of brain cells  you’ll have after reading this blog post. In the past few decades, Corbicula has continued to spread undetected, affecting native species in ways we haven’t been able to track. In the 2000s, Gerald L. Mackie comes in to play. You see, Mackie is truly a gigachad when it comes to researchmaxxing. He has written numerous papers on freshwater clams and mussels, especially in areas like the Great Lakes (like near Ohio). 

One day, however, Mackie had noticed a lack of literature and writing about Sphaeriid and Corbicula clams in particular, and decided to start a MASSIVE project: a book that intends to show every Sphaeriid and Corbiculid species, how to identify them, and also about their ecology. “Mackie 2007” is what most scientists and hobbyists refer to this book. Simply, the author’s last name and the year the book was published. To this day, this book remains an essential resource in the field of freshwater bivalves. Last year, I had found an interest in certain Sphaeriid clams, and I wanted to identify them to species. So, after hearing about Mackie 2007 from some other sphaeriidmaxxers, I had decided to pick a copy up from a university library, to read and refer to over the next year.

I had brought the book home and it had that distinctive library scent, like the smell of new furniture with an undertone of ink. To me, however, the book was a lot more than a 400 page info dump, as I had some clam shells I wanted to identify. You see, over the summer I found tiny (<3mm), white shells in the mud of a local pond. Curious, I wanted to figure out what species they were and yet I couldn’t find much information—not until I got Mackie’s book, however. There were details about separating certain clam species that I hadn’t thought about before. For example, on pages 270–275, there were a few images comparing the hinge teeth between certain species. Some species had thin and slender hinge teeth, others had thicker and curved ones–sort of similar to the shape of a tiny, tiny mango. All of this information was sorted in an easy way to understand, usually by species. Many tables and maps were present in the book, like on page 55, however one critique I have is that the information in the maps and tables did not always align, let alone the information in the species’ description: it was ambiguous if a certain species lived in a region or not. For example, the map showed Pisidium subtruncatum (nowadays Euglesa subtruncata) occurring in the northeast corner of Illinois, however the species’ description on page 342 does not mention Illinois at all. Inconsistencies like these throughout the book are my main issues with it.

So, my takeaway? Mackie 2007 might not be flawless as the tables and maps try to gaslight us, however it solos almost every other guide out there for Sphaeriidae. Reading it helped me improve my ID skills and also gain an appreciation for these clams and their role in nature. If Corbicula is the final boss, Mackie 2007 is a side quest that gives us juicy lore. And although I heavily doubt you will ever need to read the hyperspecific book Mackie 2007 is, just knowing it exists reminds us even the tiniest of clams can get their own lore book, and that’s overall a W for science.

—L.J.