by Lauren Frisch
Researchers will be able to continuously monitor ocean acidification conditions in Kachemak Bay, Alaska thanks to five new sensors to be installed in September 2017.
University of Alaska Fairbanks College of Fisheries and Ocean Sciences professor Amanda Kelley and her team installed a pH sensor at the Kasitsna Bay Laboratory in March 2017, and plan to deploy sensors throughout the bay in September. They will collect a range of ocean acidification data, allowing the researchers to study how fluctuating acidification conditions impact nearshore ecosystems, the shallow parts of the ocean right next to the coastline. This is important because Alaska has vast coastlines, vital subsistence and commercial fisheries and very little information on how ocean acidification impacts nearshore ecosystems.
Ocean acidification refers to a long-term decrease in ocean pH caused by increasing concentrations of carbon dioxide. The pH scale measures the degree to which something is acidic (like lemon juice) or basic (like baking soda).
Scientists from the CFOS Ocean Acidification Research Center have been monitoring acidification in the deeper open ocean since 2011, but there is no comparable data set documenting acidification in nearshore environments. Kelley’s team wants to fill that data gap, because nearshore environments play a critical ecological role in supporting and maintaining healthy Alaska fisheries.
“Nearshore ecosystems are complicated because they receive input from the open ocean as well as glaciers, rivers, the seafloor and more,” Kelley said. “But they are also very important, because many commercial fish and shellfish species in Alaska use the nearshore as a nursery environment. Understanding how pH fluctuates in nearshore environments will help us better understand what it might mean for species that are trying to grow and develop in the bay.”
As ocean acidification intensifies, animals like crabs and mollusks that make shells out of calcium carbonate may have difficulty growing or maintaining these shells. Commercially important finfish like salmon and pollock that rely on these organisms as a source of food may be indirectly impacted by ocean acidification if their food source is affected.
Often, the shell-building animals are even more vulnerable during their early years when they are growing and developing. Because nearshore environments serve as a nursery for many species, even small fluctuations in pH may have a substantial impact.
“Early life stages of a number of marine species spend time in these estuaries, which are highly dynamic,” said Angela Doroff, a research coordinator at the Kachemak Bay National Estuarine Research Reserve. “We are working toward establishing baseline variability and long-term trends for pH ranges in the estuary in order to better understand impacts on animals that are developing in these environments.”
But if animals are used to rapidly changing conditions in the nearshore, they might actually be more adapted to changes in pH than animals living in a more stable or constant ecosystems. Kelley explains that monitoring regular seasonal fluctuations in pH will help the research team understand what kind of pH variability nearshore species can withstand, and what they might be in for as acidification episodes intensify in the future.
This project is a collaboration between the Ocean Acidification Research Center, NOAA Kasitsna Bay Laboratory and Kachemak Bay National Estuarine Research Reserve. The research is funded by the University of Alaska Fairbanks and the NOAA Habitat Blueprint, Kachemak Bay Habitat Focus Area, KBNERR Bivalve Habitat grant.
The five SeaFET sensors the team plans to use will remain in the water for a year before being recovered to download data and check the battery. Then they can be redeployed for another year of data collection. A few times a year the researchers will go out to calibrate the sensors, or make sure the sensors are giving numbers that are consistent with actual water conditions. All of this can be done with scuba divers in small boats.
“It’s a low maintenance program,” Kelley said. “Yet the ability to collect continuous data from five sensors in the same bay is groundbreaking for Alaska. We don’t have this comprehensive a data set anywhere in the state.”
The researchers plan to leave these five sensors in Kachemak Bay as long as funding is available, allowing the sensors to build a record that can be used to reveal how Kachemak Bay pH conditions vary throughout the seasons, and how they are changing over time. But they also hope to expand the program to other parts of coastal Alaska.
Each coastline is unique, with different drivers and mechanisms that cause acidification conditions to fluctuate. As a result, species in each region may be adapted to different environmental conditions. One long-term goal is to be able to compare nearshore environments around the state by comparing data collected by different networks of sensors, Kelley said.
Additionally, by comparing measured trends in pH to biological and ecosystem data collected by other research teams in Kachemak Bay, Kelley’s team hopes to understand how ocean acidification fits into the broader context of ecosystem change in the region.
This research will benefit people living near Kachemak Bay who rely on the bay as a source of food, Doroff explains. Residents of Kachemak Bay are engaged in coastal issues, and want to have a better understanding of what’s going on in their backyard.
“For those of us living close to our food source, ocean acidification is a scary topic,” Doroff said. “People who live and work in Kachemak Bay are aware of ocean acidification, and we lack the specific ways of how it could affect our food sources, our fisheries.”