By: Alexis Estrada

Hi, my name is Alexis Estrada and I am a graduate student in Dr. Mark Steele’s lab at California State University, Northridge where I conduct field based research in marine ecology. I am interested in factors that could be affecting the population structure and recovery of the green abalone population at Santa Catalina Island. Increasing abundance of green abalone at Santa Catalina Island provides a unique opportunity to examine the basic ecology of a species that was once prominent on coastal rocky reefs and important in both commercial and recreation fisheries in California.

Adult green abalone

My research examines key habitat for green abalone to determine adult density at the island, gaining a better understanding of the movement and aggregation of adults, and gaining a baseline estimate of recruitment (addition of new individuals to the population). I began my last field season at Santa Catalina Island, and will be working on all three aspects of my project. To conduct my research I SCUBA dive at several sites around the island counting abalone, collecting recruits, and this summer I will be tagging adult green abalone underwater.

Lucy sieving a green abalone recruitment sample

I started off this summer field season as a Wrigley Institute Summer Fellow by doing some recruitment work looking for recently settled abalone recruits on the rocky reef and abalone larvae in the water column. Green abalone start their lives in the plankton, starting as eggs and continue developing through several larval stages of before finally settling onto rocky reefs. Recently settled green abalone are very small individuals that are about the size of a grain of sand. Because they are so small, we collect small boulders and cobbles from the rocky reef and gently scrub them in buckets of seawater which we filter through a fine mesh sieve to collect any recently settled abalone that were brushed off. Whatever is left on the mesh is washed into a sample jar that we can later sort through under a microscope.

My field assistant Tallula rinsing a sample into a sieve

Green abalone larvae are found in the water column. Using a similar sieving method, we can collect abalone larvae by towing a net made of very fine mesh behind a small boat to sample water at varying depths. Everything that was collected in the net can be collected into a sample jar for sorting under a microscope.

Samples and boulders from May recruitment sampling.

I am sampling for green abalone larvae and recently settled individuals every month from May until November which covers what is previously known to be the reproductive season. Abalone are broadcast spawners and reproduce when males and females emit their sperm and eggs respectively into the water column where they must mix for successful fertilization to occur. This means that individuals need to be relatively close to one another for fertilization to occur and successfully reproduce. Individual growth rates of abalone after fertilization is very predictable. By collecting recruits, I aim to back date the time of spawning based on sizes of recruits and larvae. I am hoping that by looking at recruitment patterns in green abalone we will be able to better understand the spawning season and be able to determine when spawning is taking place by identifying when recruitment is peaking.

My dive assistant Abbey, recording habitat data last summer for adult green abalone surveys

In-between recruitment sampling I will begin SCUBA surveys to identify key habitats of adult green abalone and I will start tagging adults to track their movement and aggregation. Stay tuned for more exciting research with green abalone!

By: Yubin Raut

Hello. My name is Yubin Raut and I am a second year student in the Capone lab where we study different aspects of the nitrogen cycle, specifically nitrogen fixation. Briefly, biological nitrogen fixation is the process by which microbes (bacteria and archaea) can convert dinitrogen (N2) gas found in the atmosphere into a biologically usable form of nitrogen (i.e. ammonia). Nitrogen is an important element for all living things as it is a key constituent of many essential building blocks of life such as DNA, RNA, proteins, and amino acids.

I spent the last summer investigating the role of nitrogen fixing microbes associated with an invasive macroalgae, Sargassum horneri and we found that these microbes play a more stringent role during the senescence (decay) life cycle of the macroalgae. The results from last summer has motivated me to investigate the role of nitrogen fixers in other species of macroalgae (including red, green, and brown macroalgae). Additionally, past researchers have also found nitrogen fixation to be an important source of nitrogen for green macroalgal species (i.e. Codium spp.) and I am interested to see what role these microbes may be playing with a wider variety of macroalgae.

The Wrigley Marine Science Center (WMSC) on Santa Catalina Island is an ideal place to pursue my research interests as it houses a marine facility that is well equipped to support my laboratory work and it’s the perfect place to go searching for a wide array of macroalgae. I am incredibly lucky to receive the 2017 Victoria J. Bertics Summer Fellowship which will allow me to spend another great summer at WMSC doing research. In fact, I have already jumped head first into my summer research, spending the last 3 weeks out on the island setting up my lab space and troubleshooting my primary instrument (gas chromatograph). It has been an interesting summer thus far with plenty of research ideas but with one major setback: having applied for my scientific collection permit a little late, there was a moment of real panic during which I thought I wouldn’t be able to collect the different species of macroalgae I am interested in, but as you can guess, this is kind of vital for my research!

The gas chromatograph (GC) where I run all my samples.

So during the past 3 weeks, I began investigating nitrogen fixation in the sediment of Catalina Harbor, and also sediment collected from different sites around Big Fisherman Cove. There was previous work that showed active nitrogen fixation at Catalina Harbor and I wanted to supplement this work with new research questions. Thus far, I have been getting positive results and it has been a really interesting change of pace collecting sediment at Cat Harbor during low tides as opposed to snorkeling around looking for macroalgae. Luckily, I found out that my permit was approved and that I should be getting it any day now which will allow me to resume my research with macroalgae. What’s really exciting now is the possibility of combining my new research interest in sediment with macroalgae. My main motivation behind wanting to combine these two systems is because they are so interconnected in nature with most macroalgae interacting directly with sediment during much of their life cycle. The summer looks very promising with regards to research but it will also prove to be very demanding. Fortunately, I will have an extra pair of hands soon, as I am partaking in the Research Experience for Undergraduates (REU) program as a mentor and I will be joined on the island very soon by my REU participant.

An example of my incubation setup. (S. horneri pictured above)

Apart from research, the island has also been keeping me busy with plenty of education and outreach volunteer opportunities, most of which include snorkeling around Big Fisherman Cove with different groups that come out to WMSC. Some of my favorite snorkeling moments have actually been at night time during which we have been able to observe some extraordinary bioluminescence. There have also been some enjoyable kayaking sessions during which we attempted to race backwards (much harder than anticipated). Unfortunately, with some of the new renovation projects taking place at WMSC, the ping pong table has been in storage and so I’ve been dearly missing one of my favorite island activities; surprisingly, those of us here have been making up for the lack of ping pong with long sessions of bocce ball. Lastly, I was finally able to explore Avalon during Memorial Day weekend and it proved to be a fun town with exceptionally good pizza! I’m looking forward to the rest of summer and all the good times that lie ahead.