Three minutes, one slide, and lots of fish eggs

By Jana M. del Favero

Would you be able to explain your research to an audience of academics from all different disciplines, in just 3 minutes, with only one slide? That is the premise of a competition called the Three Minute Thesis (3MT). 3MT was created at the University of Queensland, Australia in 2008, and it has been performed at the University of Massachusetts Dartmouth, USA since 2011. (Details about the competition can be found here: http://www.threeminutethesis.org).

While thinking about the goals of this blog, I decided to participate in the competition this year, as it does exactly what we try to do here: talk about science to a diverse audience while keeping it interesting and educational. I signed up thinking only about the training; I would have to prepare and memorize my text and then deliver the presentation (in English!). Of course, I also had the ultimate goal of winning (who turns down a chance to earn $1,000?).

Unfortunately, I did not get rich on April 29th, 2015, but as expected, it was great practice and lots of fun. It was interesting to watch presentations about the research from various fields: engineering, arts, administration, etc. There were nervous people and people who seemed to have come straight from a theater stage. You can watch some videos of previous years by visiting the following website: http://www.umassd.edu/graduate/spotlights/three-minutethesiscompetition/.

You can read the transcript of my talk and learn more about my research below:

Many people do not know, but fisheries management is not just based on adult population data. It is also important to study early life stages for better stock management. For example, as fish eggs are usually spawned in the water column, knowing when and where they are helps to define spawning sites and periods.

But, before doing any kind of fish studies, it is necessary to know who they are. Fish egg identification is time consuming and difficult. After sampling on board, you need to sort all of the fish eggs from the plankton sample, using a microscope. Sorting the eggs from the family I am studying is easy because their eggs have an ellipsoid shape.

The problem is reaching the species identification. As each group presents different size and shape, the identification has previously been done by manually measuring each egg and then counting.

Figure 1. The single slide presented during the competition. The eggs illustrations are from Nakatani (1982).

In my doctoral thesis, I want to verify long-term fluctuations in the abundance and distribution of eggs from a fish named Argentine anchovy on the Brazilian coast. This small fish is one of the most common fisheries resources in Argentina and Uruguay. At the Brazilian coast they haven’t been commercially fished yet, but some studies have suggested that Argentine anchovy can be sustainably fished in Brazilian waters.

Coming back to my thesis, when I mentioned that I am studying long-term fluctuations, I didn’t mention that by long-term I meant 40 years of data, totaling almost 2000 samples. That is a huge amount of samples and it would take my whole PhD period just to identify all the eggs. The solution was to create a faster and more accurate methodology, so I did it.

I used a digital camera attached to a microscope to image the eggs, and using the photos, I got the measurements. After that, I created a model that automatically gave me the counts of eggs within each species. This new model has over 90% accuracy and can be used by any researcher to optimize their time and effort.

In the end, besides taking four years to identify the eggs for my thesis, I identified more than 100,000 anchovy eggs in just one year, allowing enough time to continue my research project.  

If you are interested in this methodology, the paper is already in publication, and it can be accessed in the following link or requested by email.

http://onlinelibrary.wiley.com/doi/10.1111/jfb.12594/abstract

See you soon.

Devastatingly beautiful: the growing problem of Lionfish invasion

By Corey Eddy and Jana M. del Favero

Two lionfish have been sighted in Brazil, both in the southeastern area of Arraial do Cabo (Rio de Janeiro). The first one was in 2014 and another more recently in March 2015. But with only two individuals spotted, why should we care?

The lionfish!

Brazilian experts are still debating how these lionfish ended up in the Brazilian waters and if there may be more individuals in deeper waters, not observable by divers (details at: http://ciencia.estadao.com.br/blogs/herton-escobar/mais-um-peixe-leao-e-encontrado-na-costa-brasileira/).

While there is no consensus, I asked a colleague, Corey Eddy, to write about the invasive population of lionfish in Bermuda; I wanted to know what is being done there and what measures could be adopted in Brazil. Below it is the text he wrote:

Since the discovery of lionfish in Florida in 1985, their population expanded rapidly to stretch from Venezuela to Rhode Island (US). It was thought their range of invasion could eventually stretch as far south as Uruguay. As lionfish are recognized and avoided by prey in their native territory, they have evolved into opportunistic predators with broad diets. However, due to prey naivety in their invasive range, lionfish are able to consume large quantities of invertebrates, juvenile fish, and small-bodied adult fish, many of which play important ecological or economic roles. Consequently, research shows that lionfish can reduce juvenile reef fish populations by nearly 80% in as little as five weeks. Bolstered by the lack of any natural predator, lionfish populations in the Atlantic have reached densities far greater than in their native range, with the potential to affect community structure, biodiversity, and the health of coral reef ecosystems. Fortunately, they are delicious and it only takes one minute to remove their dangerous spines, making them perfectly safe to handle. If we can create a fishery for them, we can save the ocean. We have to eat them to beat them.

Representation of the worldwide lionfish distribution. Diagram by Naira Silva

Source: Lionfish illustration (http://www.supercoloring.com/pt/desenhos-para-colorir/peixes).

My doctoral work is part of a larger project, funded through the UK’s Department of Environment, Food and Rural Affairs, that is investigating the biological and ecological characteristics of the lionfish population around Bermuda and the potential impact lionfish may have upon the structure and function of Bermuda’s coral reef ecosystem. For my first chapter, I will be using the data we collect on lionfish abundance and distribution to estimate the population size. Our team is assessing lionfish abundance via underwater visual surveys at 15 sites in each of five depth zones across the Bermuda platform (10, 20, 30, 45, and 60m) using SCUBA or appropriate technical diving equipment (i.e. trimix diving with multiple tanks). Using a roving search protocol that encompasses cryptic habitats, divers record all lionfish seen and attempt to capture each individual using a pole-spear. Following capture, all lionfish are measured, weighed, dissected, and processed for further analyses. Belt-transect surveys of reef fish, focusing upon small and cryptic species, are conducted concurrently to determine the abundance and distribution of potential prey. A number of these sites are being resurveyed after one year to assess re-colonization rates. This data will also facilitate the development of a distribution map that aids removal activities targeting lionfish at key locations and times that account for seasonal population fluctuations and movement patterns.

Photo by Jorge Sanchez

My next two chapters will document the life history characteristics of this species to estimate population growth as it pertains to their potential ecological impact. In chapter two, I will examine the demographics of the lionfish population as well as growth rates and longevity of lionfish in Bermuda. This work utilizes standard otolith (“fish ear bone”) aging techniques applied to specimens captured during our underwater surveys and opportunistically from other divers, commercial fishermen, and permitted lionfish hunters. Following this, my third chapter will examine the reproductive condition and quantify the fecundity of lionfish. Gonads will be weighed, sectioned, and analyzed by traditional histological methods to determine overall fecundity, reproductive seasonality, and the developmental stage of fish, thus providing an estimate of the reproductive potential driving the overall population growth.

In my final chapter, we are investigating the feeding ecology of lionfish to explore the impact they may have on the native fish and invertebrate communities, as well as the entire local ecosystem, and to identify factors driving the population’s distribution. This research involves conventional stomach content analysis (SCA) complemented with more advanced stable isotope analysis (SIA) that reveals details not detectable through traditional methods. Because the stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N) in the tissues of predators are directly related to the ratios found in their prey, the change in these ratios relative to a standard, δ13C and δ15N, are used to indicate the primary carbon sources for a consumer and an estimate of trophic position, respectively. To further indicate the potential impact of lionfish on Bermuda’s reef ecosystem, we will also perform this analysis on prey species (i.e. those identified by the SCA) and others we know are competing with lionfish for these same resources. By plotting δ13C and δ15N of lionfish and these various species, we can see the extent to which lionfish are utilizing resources needed by native species.

When completed, this project will estimate the extent to which invasive lionfish could impact Bermuda’s coral reef ecosystem and help mitigate that impact by providing data on lionfish abundance and distribution to assist the Bermuda Lionfish Task Force and the Department of Environmental Protection (http://www.lionfish.bm) in developing a comprehensive plan that facilitates large-scale, long-term removal of this species from local waters. Controlling and reducing the continued growth of the lionfish population is a crucial part of any effort to minimize negative impacts on native fish species and coral reef ecosystems, and avoid secondary impacts on fisheries and tourism.

In addition to my doctoral research, I am heavily involved in public education and one of the projects I work on may be very useful to implement in Brazil. As a volunteer for the Ocean Support Foundation (http://www.oceansupport.org), I run the Bermuda Lionfish Culling Program on behalf of the Department of Environmental Protection. This program allows any Bermudian resident, over 16 years of age, to receive the proper training and a special permit to hunt lionfish. This is different from a traditional spearfishing license because permitted lionfish hunters are allowed to hunt lionfish while using SCUBA, within one mile of shore, and on shipwrecks and other protected sites, situations normally forbidden by Bermuda law. To date, we have certified over 500 hunters, all of whom are a major help in removing lionfish and keeping Bermuda’s reefs clean and healthy. As Brazil has only recently been invaded, these early days are the perfect opportunity to mobilize SCUBA and free divers, fishermen, and environmentalists to get into the water and start hunting. Every lionfish that is removed greatly helps to preserve and protect Brazil’s marine environment, especially at this early point, when there may be very few lionfish around.  

Corey Eddy biography:

Photo by Groundswell Bermuda.

Corey Eddy is a PhD candidate at the University of Massachusetts Dartmouth. He received his bachelor’s degree from the University of Rhode Island, whose study abroad program first brought him to Bermuda for a semester at the Bermuda Institute of Ocean Sciences. He is also a Fellow through the National Science Foundation’s Graduate Research Program and a member of the Bermuda Lionfish Task Force. As a volunteer for the Ocean Support Foundation, he developed and currently manages the Bermuda Lionfish Culling Program on behalf of the Department of Environmental Protection. His research interests focus on studying the life history characteristics, habitat use, and feeding ecology of ecologically important predators.
Contact: corey.eddy@umassd.edu