Kristy Kroeker is an ecologist and a professor at UC Santa Cruz. She has been studying ocean acidification for 10 years, most recently focusing on kelp forests in Sitka Sound.
What element of OA do you work on in Alaska and where?
As an ecologist, I am studying the effects of ocean acidification and warming on kelp forest ecosystems and species in southeast Alaska. We think that ocean acidification will increase the energetic demands of a wide range of vulnerable species, such as abalone and sea urchins, and our work is trying to determine how the effects on individual species will scale-up to affect entire ecosystems and species at the top of the food webs that people often care about.
What drew you to this type of work?
I have always been interested in doing science that is relevant to people and can inform decisions. I started studying the ecological effects of ocean acidification over ten years ago, when I realized that our understanding regarding how entire ecosystems might change in the future and how those changes could affect our coastal communities was very limited. I started working in kelp forests in the last five years because kelp provides food and habitat for many species that we care about, from abalone to rockfish, but there has been very little research on how they might change with continued acidification and warming.
Could you tell us more about meta-analysis and how it can help?
Meta-analysis is a quantitative way of summarizing a bunch of different studies (that may have been done for different reasons) to identify generalities in a field of study. For ocean acidification research, meta-analysis can be really useful because we don’t have the resources to study the effects of ocean acidification on every species in the ocean. Meta-analysis can allow us to see if general patterns in response to ocean acidification emerge across the wide variety of experiments and species we have studied. We can then use the results from meta-analysis to build hypotheses for the understudied species or systems. As an experimentalist, I also find that meta-analysis is helpful in putting my own studies and results in context and identifying gaps in our understanding.
We understand you work with kelp forests – how common are they in Alaska and what can we learn from them?
Kelp forests are an incredibly beautiful and important ecosystem. The ecosystem is based on the presence of kelp, which serves as a habitat and food source for many culturally and economically important species in Alaska, from Lingcod and rockfish to herring and abalone. Kelp forests are found from the Southeast, the Gulf of Alaska, and throughout the Aleutian Archipelago, although the dominant kelp species differs in each region.
In southeast Alaska, where I have been working for the last few years, the dominant kelp is Macrocystis pyrifera – the giant kelp. This is the same species that is found along the coastlines of California, where I live, and southeast Alaska is the northern range limit for this species. Because cold water can hold more carbon dioxide, Alaska already experiences relatively corrosive waters during winter months. We are using these giant kelp forests at the northern edge of their range to understand how ecological processes and energy flows through food webs vary seasonally – and trying to determine what these seasonal differences can tell us about kelp forest food webs in the future.
What are some of the most surprising findings you’ve discovered?
We just finished a really interesting study on the effects of ocean acidification on pinto abalone that was led by one of my undergraduate students. She found that pinto abalone can continue to grow in conditions we expect to see in the year 2100 with continued acidification, but only when the abalone have access to a wide variety of algal food sources. Unfortunately, the algal community is greatly diminished during the winter months in Alaska, due to a lack of light and storms that rip out the algae. When the food choices for abalone are more limited, which we think is representative of the winter months, she found that pinto abalone could already be suffering reduced growth during winter, when the water is more cold and corrosive.
Can you tell us about a memorable time in the lab or in the field?
We are very lucky because we get to work underwater for our research. Every time I get to dive in the kelp forest in Sitka Sound is memorable. The kelp forests in southeast Alaska are fascinating and beautiful, and the winter months are incredibly clear. My favorite part is the seafloor under the kelp canopy during the winter, which is covered by a carpet of pink coralline algae, which provides hiding spots for hundreds of little colorful invertebrates and fishes. It’s really spectacular.