Saving the Sea Floor

Illustration by Alyssa Long

Rachael Shaver

Contributing Writer

The history of mankind’s environmental abuse has caused visible effects on the species that occupy the affected ecosystems. Interestingly, the environment itself plays a tremendous role in the biodiversity of various ecosystems. Raine Detmer, a graduate student at UC Santa Barbara (UCSB), has created a new mathematical model that mimics the effects of environmental stressors, specifically storms, on diverse kelp forest ecosystems. 

Detmer’s research focuses on how kelp has a disproportionate effect on the rest of the ecosystem as a keystone species and how its removal by storm, mimicked by her mathematical model, influences the biodiversity of the benthic community — a community of organisms that live on, in, or near the seabed, within the ecosystem. In an interview with The Bottom Line, Detmer explains her focus on the benthic kelp forest communities and how their sea-floor presence has a bottom-up influence on the rest of the ecosystem. 

“There are the two main groups that occupy space on the bottom of the ocean floor, creating the benthic community,” Detmer explained. The invertebrates like sea anemones, sponges, or sea squirts and then the macroalgae. We wanted to see what would happen if we removed the kelp [in the benthic community] at different frequencies or different amounts and how it would impact the environment of the benthic communities.” 

“Kelp, which is this foundation species, [meaning] it has this disproportionate effect on the rest of the ecosystem, provides a habit and alters the physical environment [of the benthic communities],” Detmer said.

Detmer’s model accounts for storms and the consequences they have on the kelp. The model assumes the experimental variable being measured is the effects of the storm, while every other variable remains constant. Detmer describes that the model “accounts for one variable, which provides her with an accurate measurement of the effect,” it has on the benthic communities. The Santa Barbara Coastal Long Term Ecological Research Program (SBC LTER) has 20 years of time series data on kelp, invertebrate, and macroalgae abundance, which Detmer utilized to compare the results yielded by the controlled mathematical model to the benthic system itself. 

“We were able to look at the system over time using Santa Barbara Coastal LTR and then we can model the system over time. And then we can compare the two and see if the model is giving a reasonable assumption compared to the [real] system,” she explained. Waves and swell data illustrate whether or not storms had occurred, and in congruence with the data provided by SBC LTER on kelp abundance, the researchers were aided with information that was vital to demonstrating the accuracy of the mathematical model. 

Detmer’s model accounts for storms and the consequences they have on the kelp. The model assumes the experimental variable being measured is the effects of the storm, while every other variable remains constant.

The results of the experimental predictions of the model were consistent with the data that was provided by SBC LTER in its suggestion that the variability in disturbances affecting giant kelp abundance has measurable consequences for two benthic community species that are competing with each other for space on the seafloor: macroalgae and invertebrates. 

Since macroalgae require light and invertebrates don’t, the researchers hypothesized that when less kelp is present, the macroalgae should be in greater abundance than the invertebrates, as less kelp provides opportunity for the macroalgae to be exposed to up to 90 percent more light, allowing the algae to out-compete the invertebrates for space at a faster rate. The researchers were expecting this outcome in their hypothesis. However, they also discovered that the removal of kelp was not the sole factor affecting the benthic communities in this manner.  

“It was also the scraping of the bottom of the seafloor, which we didn’t necessarily predict. It wasn’t predicted that what is also going to matter is how much the bottom itself was disturbed, not just if the kelp was removed,” Detmer revealed. “It was the most exciting part [of the experiment] because it wasn’t as expected.” 

Detmer, who grew up in Ventura, California, details spending childhood days on the beach. Exploring the sandy shores, noticing the kelp fronds, and laying around led to the development of a fascination with the kelp forests. She described a keen curiosity and interest in mathematical models explaining ecological processes after taking a class during her undergraduate studies with Holly Moeller, an assistant professor in the department of Ecology, Evolution, and Marine Biology. She proceeded to combine these two passions in her research, and is now a first-year doctoral student in the lab of Holly Moeller. Detmer’s findings have been published in Ecology

This research provides insight necessary for a more nuanced understanding of benthic ecosystems. Being equipped with explicit details on the processes that are taking place within our environment allows us to better evaluate what must be done to effectively fulfill conservation efforts in these ecosystems, especially given the reality of the future that our ecosystems will be facing. It is essential that research on understanding the fragile nature and ever-changing processes that take place within our ecosystem are taken seriously in hopes of both saving withering ecosystems and conserving the thriving ones.