A university is a collection of departments that agree not to talk to each other.
I ran into an article claiming that cows radically changed the marine ecosystem in the second half of the 19th century. The title of the piece is "How Cows Destroyed an Entire Marine Ecosystem in California." It's from 2021 so it's not particularly fresh as a topic, but I thought it would be a good example of what can happen.
This article is a summary of a scientific study called "Nineteenth-century collapse of a benthic marine ecosystem on the open continental shelf." The study is real science with sample taking, sample analysis, radiocarbon dating, and top-level sciencey language. Basically it proves that long ago there were gravel dwelling filter-feeders in clear waters, but by the mid 20th century these were replaced with various mud dwellers living in mud.
The study area was small, including three Southern California areas. The study says, "These three sites are Short Bank in Santa Monica Bay, and the western and eastern parts of the Palos Verdes shelf." Having ascertained that this change in the biome occurred, and having quantified the organisms involved, possible causes are sought. Those mentioned are: a.) sewage effluent; b.) global warming; c.) siltation owing to livestock grazing and farming.
The study emphasizes: "Heavy grazing has many negative effects, but most notable in this context is soil compaction from trampling that increases surface runoff of rain and thus the potential for soil erosion. Sediment transport to the sea, always episodic in this semi-arid setting, was thus almost certainly much higher during the nineteenth century than during preceding millennia of occupation by native hunter–gatherers."
"Thus almost certainly" is what somebody writing a report says when the data is thinnest and most suspect. It's what you say instead of something firm and sciencey. Well, the causes are secondary. The conclusion of the study is that we need to study this topic more. (More funding! More studies! More beach time!)
Here's a free suggestion for the next study. Lay off the global warming and the cows and the peaceful, ecologically-aware indigenous hunter-gathers, and think about these two words: HYDRAULIC MINING.
Before gold was discovered in Coloma, California in 1848, gold was discovered in the San Gabriel Mountains in 1842. Here's an article about it that would be a really good resource except the San Bernardino Sun wants to sit on it like a broody hen rather than let you read it. But here are a whole bunch of pictures that feature hydraulic mining. Yeah, it was horrifically damaging to the environment; the original San Gabriel mines pretty much choked out everybody that relied on Placerita Canyon water. Hydraulic mining was such a big deal and caused so much environmental damage that I'm surprised ecologists don't know about it. But then, the scientists are products of a university, where the History people never talk to the Biology people.