Meet Our Team: Emily Rose Nelson

1. What’s your role in the lab?
Hey guys, I’m Emily! I’ve been working with the Shark Research Team at the University of Miami for about 4 years now. During my time with the RJ Dunlap program I have been involved with a number of projects. I have been the shark satellite tracking coordinator since 2013. I am responsible for keeping track of all our satellite tagged sharks. Nightly, I receive emails that indicate which of our sharks have transmitted throughout the day. Using a number of different databases I can then examine the location and movement of animals. From here, the tracks are updated on our website so the public can view the animal’s movement in near real time. The information we receive from these tags is used for numerous research projects going on in the lab to further enhance shark conservation. My current research involves looking at the movement patterns of tiger sharks and comparing it to a number of different morphological variables. In particular, we are trying to determine what exactly (i.e. tail size, body condition, reproductive status) determines how far, how fast, and where an individual will move.

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2. Tell us a little about yourself.
I received my Bachelor of Science Degree in Marine and Atmospheric Science at the University of Miami, Rosenstiel School of Marine and Atmospheric Science in 2014 and will be starting work towards my Masters of Science in Marine Affairs and Policy with Dr. Hammerschlag in Fall 2015. Outside of the lab, I can probably be found tutoring (I love working with kids) or playing with my dogs and cats. I love avocados, water skiing, concerts, Blackhawks hockey, and driving across the Rickenbacker Causeway.

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3. How did you get interested in marine biology and conservation?
For as long as I can remember I have wanted to spend my life working with the ocean and the amazing creatures within it, forcing me out of my land-locked home town of Chicago.

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4. What’s your favorite part about working in the lab?
Working with the shark team at RSMAS has been one of the best experiences of my life. The adrenaline rush that comes after successfully completing a work up on a 350 centimeter tiger shark in the Bahamas is indescribable. Running statistical tests on a new set of data and finding a significant result is super exciting. However, the best part about being a member of this lab is the team I am surrounded by. It is an honor to work alongside some of the most talented and passionate people in the field. I am lucky to be able to learn something new from my colleagues every day and even luckier to call them some of my best friends.

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Evolution of Motherhood: The Importance of Mature Female Fish

By Daniela Ferraro, RJD Intern

Older, female fish are becoming a necessity for the continuation of trophy-fish hunting and sustainable commercial fishing. Looking at both freshwater and saltwater species, the presence of larger, more mature fish increases the productivity and stability of fish populations. Dr. Mark Hixon, of the University of Hawai’i at Manoa, refers to the loss of big fish as “size and age truncation.” Big, old, fat, fertile, female fish, affectionately nicknamed BOFFFFs, have proved the ability to produce significantly more eggs than younger fish. They also can spawn at different times and places, allowing them the option of evading potential predators and threats to their offspring. Efforts to protect older, larger fish include creation of marine reserves, which act as no-take zones. Marine reserves allow fish to spawn throughout their entire lives. As large fish, BOFFFFs are a valuable commodity in commercial fishing, as fisheries tend to target marketable commodities. This specified targeting alters a fishery’s modes and methods: through the narrowing of mesh size or gear type. Drift nets and long lines are used in the removal of larger fish from certain populations. To some extent, even bait type and hook affects the type of fish caught. Slot limits are placed on commercial fisheries, limiting them to catching only medium-sized fish. Although egg size variation among a single species may be narrow, across a diverse range, significant maternal effects have been noted in terms of larger egg size.

BOFFFFs: Big (1.1m), old (ca.100 years), fat (27.2 kg), fertile female fish: Shortraker rockfish (Sebastes borealis). Image Source: Karna McKinney, Alaska Fisheries Science Center, NOAA Fisheries Service

BOFFFFs: Big (1.1m), old (ca.100 years), fat (27.2 kg), fertile female fish: Shortraker rockfish (Sebastes borealis). Image Source: Karna McKinney, Alaska Fisheries Science Center, NOAA Fisheries Service

More mature females produce more, and often larger, eggs that typically develop into larvae that can withstand more intense challenges like starvation and have a faster growth rate. This is partly due to the physical body size, as a larger fish translates to a wider body cavity to allow for the development of larger ovaries. BOFFFFs have a tendency towards earlier and longer spawning seasons. With this flexibility, these fish can withhold spawning in unfavorable conditions. Once the danger of predation, or other threats, has passed, BOFFFFs can spawn abundantly and improve recruitment. Hixon refers to this phenomenon as the storage effect. This ability is preferential when considering commercial and differential fishing. The targeted removal of BOFFFFs results in a truncation of size and age structure of a specific population. The removal of older fish from an overfished population will increase their probability of species collapse. The assumption that younger female fish contribute equally to production and stock is detrimental to the future of sustainable fishery stocks.

Fishery productivity would find stability in the implementation of old-growth age structures. Berkeley suggested three methods to limit the overfishing of BOFFFFs: slot size limits with both minimums and maximums, low rates of fishing mortality, and marine reserves.  This can be accomplished with enforcement of both marine reserve no-take zones as well as catch limits. Marine reserves act not only as a direct safe place for fish to thrive and procreate, but also as a healthy influence on surrounding waters. They give maturing fish an area to develop, spawn and seed nearby fisheries.

Cape Rodney-Okakari Point, Goat Island Marine Reserve, New Zealand. Image Source: Wikimedia Commons

Cape Rodney-Okakari Point, Goat Island Marine Reserve, New Zealand. Image Source: Wikimedia Commons

Marine reserves act to provide ecosystems and environments for fish to not only reach sexual maturity, but past that. In addition, larvae from healthy marine reserves are found to seed the areas directly adjacent. This will assist in the replenishment of overfished and exploited populations. By integrating large-scale marine reserves, it is believed that it is possible to halt and reverse the decline of global fisheries while also protecting marine teleost, mammal, and invertebrate species. The decrease in mortality due to the protection of species by marine reserves and the subsequent increase in productivity has been seen in both temperate and tropical locations. Since marine reserves are located along reefs, estuaries, and kelp beds, it provides a large range in the protection of a diversity of species.

In a study conducted by Steven Berkeley et al, featuring 20 female black rockfish (Sebastes melanops), from five to seventeen years, it was found that larval groups from the older females grew three times faster than their counterparts. Larvae from the older fish also survived starvation twice as long. According to Berkeley, this is due to the provision of larvae with energy-rich triaglycerol (TAG) lipids as they increase in age. The TAG volume found in oil globules is positively correlated with age, growth rate, and survival. However, maternal effects can’t be classified as consistent across every species of teleost fish. Instead, research indicates that maternal effects have developed across a diverse taxonomic range. With the removal of matured female fish, populations are more likely to develop damaging consequences in terms of biodiversity and productivity.

 

References

Berkeley, Steven A., Mark A. Hixon, Ralph J. Larson, and Milton S. Love. “Fisheries Sustainability via Protection of Age Structure and Spatial Distribution of Fish Populations.” Fisheries 85.5: 23-32. Print.

Gell, Fiona R., and Callum M. Roberts. “Benefits beyond Boundaries: The Fishery Effects of Marine Reserves.” Trends in Ecology & Evolution 18.9: 448-55. Print.

Hixon, M. A., Johnson, D.W., and Sogard, S. M. BOFFFFs: on the importance of conserving old-growth age structure in fishery populations. – ICES Journal of Marine Science, 71: 2171–2185.

Can Facebook be used to increase scientific literacy?

By Sarah Hirth, RJD Intern

With the rising popularity in social media, more and more scientists are using social media platforms for education and outreach. The case study “Can Facebook be used to increase scientific literacy?” aims to investigate how effective Facebook is when it comes to educating people about the oceans.

Facebook is an excellent platform for fostering communication between scientists and citizens, thus also making it easier for experts to inform the general public about current issues. It has been observed that users find learning through Facebook fun, but how effective is this method as a platform for learning?

“Can Facebook be used to increase scientific literacy?” focuses on the Monterey Bay Aquarium Research Institute (MBARI). MBARI, is a private marine research institute that specializes in the innovation of technology for the purpose of studying the ocean.

Aiming to increase the number of people reached per post, MBARI decided to change their posting strategy. This included posting at different times, and changing the type of media posted along with a few other factors. The results and conclusions discussed in this case study, compare their new finding to their previous numbers. All data used in this case study came directly from MBARI’s Facebook page.

Although the change in posting strategy did not yield in an increased number of fans, MBARI was able to make some observations. One of the main observations was that stories posted with a photo or video reach 35.3% of the fans, whereas stories posted with only text, or a link will only reach 28.55%. Another factor in increasing the reach depended on the frequency of posts, where “the higher the number of days with a story in a week, the higher the average organic reach will be.” Although frequency was one of the observed factors, “if stories are posted five days a week, the days of posting only have a minor impact on the average daily organic reach.”

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MBARI also found a correlation between the amount of words used and the number of people reached. However, most of their long texts were associated with photos, whereas short text was associated with links, thus making it difficult to argue that this had a direct impact on the reach. Apart from this, the data also showed that the organic reach on a given day increases by 18.26% if a story is posted the day before.

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The final results showed that although Facebook can be a useful platform for raising user’s interest and giving them the opportunity to learn more, there is little opportunity for fans to develop their ocean literacy through social participation. This is due to the fact, that most Facebook users don’t follow the pages to engage in social practices. During this case study it was also observed that some people feel too uncomfortable or too insecure to comment on posts made by MBARI. However, once a user shares the story; their friends will be more comfortable and therefore more inclined to comment on posts. “The shared stories seem to be one of the main keys to increase participation and support the development of domain specific learning on Facebook.”

 

Shark Tagging with the University of Miami Alumni Association

By James Keegan, RJD Intern

Saturday’s trip looked like it would be a gloomy one with overcast and rain. I was excited for the catered trip, but I left for Crandon Marina with a sense of dread. The prospect of tagging sharks in choppy waters and cold rain did not thrill me. However, once the RJD team loaded the Diver’s Paradise, the skies cleared up a little. After Captain Eric and Neil went over safety and gear deployment, members of the Alumni Association and the RJD team introduced themselves. As we left for Soldier Key, the skies completely cleared, and I breathed a sigh of relief. The day was absolutely gorgeous.

With help from the Alumni Association, we deployed our gear quickly and took environmentals. We went for a brief swim, and afterwards Neil gave a great talk explaining our shark workup and the value of our research. With everyone now prepared, we returned to check our lines.

On our first line of the day we caught a nurse shark, and luckily for us, it was a fairly calm one. With help from members of the Alumni Association, we quickly performed the workup and released the nurse shark. We also caught nurse sharks on lines four and seven, but unfortunately, the nurse shark on four unhooked itself and swam away before we could get it on the platform. The shark on line seven had the largest head on a nurse shark that I have ever seen, and it was so feisty we did not bother trying to take blood. With three nurse sharks in the first set of lines, I was prepared for a long day filled with bruising battles. Nevertheless, I was content as the delicious catered lunch would sooth any pain.

 

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Picture: Measuring the nurse shark. Caption: A participant helps us measure a nurse shark.

However, my prediction was not correct as we only caught one more shark during the trip. A large lemon shark, about nine feet long, waited for us on the last line of the second round. Again, we quickly performed our workup and got the shark back into the water. I was glad members of the Alumni Association got a chance to feel the real roughness of sharkskin, because nurse sharks have comparatively smooth skin.

 

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Lemon shark with pump. Caption: A member of the RJD team removes the water pump from the lemon shark’s mouth as we prepare it for release.

Although we did not catch any more sharks, our last catch of the day happened to be a barracuda in the third round of drumlines. We reeled it in and saved it to use as bait for the following day’s trip. Overall, we had a great day on the water, and I was glad alumni were able to come on board and participate in our research.

 

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Everyone. Caption: Members of the University of Miami Alumni Association and RJD team throw up the “U”

Cetacean Species Affected by Warming Arctic

By Hannah Armstrong, RJD Intern

Global climate change, among other anthropogenic issues, is becoming an increasingly significant threat to the Arctic region of the world.  Specifically, higher average temperatures and rapidly disappearing sea ice are of conservation concern for ice-dependent species.  Arctic marine mammals are specifically adapted to take advantage of the climatic conditions that have prevailed in the Arctic for millions of years, and have been a target of conservation based on their role in the functioning of Arctic ecosystems and surrounding communities.  Despite these conservation concerns, with impacts of climate change likely to worsen in coming decades, there is increased industrial interest in Arctic areas previously covered by ice.

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A graph showing the evident decline in average monthly arctic sea ice extent from September 1979 through 2012 (Reeves et al).

In a recent study, scientists observed and mapped the distribution and movement patterns of three ice-associated cetacean (marine mammal) species that reside year-round in the Arctic: the Narwhal (Monodon monceros), Beluga (white whale, Delphinapterus leucas), and Bowhead Whale (Balaena mysticetus) (Reeves et al. 2013).  Then they used these ranges and compared them to current and future activity sites related to oil and gas deposits, exploration, development and commercial shipping routes, to assess areas of overlap, as a means of highlighting areas in the Arctic that might be of conservation concern.  Some of the results indicated the sensitivity of Bowhead whales to industrial activity; the sensitivity of Narwhals to climate change and noise, as well as a shift in distribution due to ice conditions; and the sensitivity of Beluga whales to noise, as well as a wider distribution extending into the sub arctic (Reeves et al. 2013).  These observations ultimately triggered the need for a better understanding of the implications of environmental changes in the Arctic for cetacean species, in order to develop effective conservation and management policies (Reeves et al. 2013).

Poorly documented shipping routes and operations, in addition to accelerating Artic pressures in Arctic Norway, Arctic Russia, the Alaskan Arctic, Arctic Canada and Arctic Greenland, indicate that immediate measures need to be taken to mitigate the impacts of human activities on these Arctic whales, as well as the people who depend on them (Reeves et al. 2013).  As indicated by researchers, some of these measures include: careful planning of ship traffic lanes (re-routing if necessary) and ship speed restrictions; temporal or spatial closures of specified areas (e.g. where critical processes for whales such as calving, calf rearing, resting, or intense feeding take place) to specific types of industrial activity; strict regulation of seismic surveys and other sources of loud underwater noise; and close and sustained monitoring of whale populations in order to track their responses to environmental disturbance (Reeves et al. 2013).

After comparing maps of Arctic whale ranges with maps of recent and anticipated oil and gas activity and shipping traffic in the Arctic, researchers noticed the unquestionable overlap between Arctic whales and harmful human activities.  Based on unparalleled current and predicted rates of climate change, the futures of these three Arctic whale species are uncertain.  Based on the significance of these species, both culturally and for proper functioning of the Arctic ecosystem, well-informed management decisions related to human activities will be imperative going forward.

 

Reference:

Reeves et al.  Distribution of endemic cetaceans in relation to hydrocarbon development and commercial shipping in a warming Arctic.  Marine Policy 44 (2014).

“Narwhals Breach.” WikiMedia Commons. WikiMedia, 1 Oct. 2012. Web. 29 Jan. 2014.

 

 

Fish living in the “twilight zone” have a greater biomass than previously thought.

By James Keegan, RJD Intern

Mesopelagic fish, fish living at depths between 200 and 1000 meters in the ocean, reside in water with very low levels of light. Although they are typically small, mesopelagic fish constitute the largest biomass of fish in the world because of their immense numbers. Previous estimates state that there are about 1,000 million tons of mesopelagic fish worldwide. However, using data collected on the Malaspina 2010 Circumnavigation Expedition, Irigoien et al. 2014 show that there are about 10 times more mesopelagic fish than previously estimated. Such an increase in an already massive fish community alters how we determine the role mesopelagic fish play in ocean food webs and chemical cycling.

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A man holding the mesopelagic species Stenobrachius leucopsaurus. It belongs to a family of fish commonly known as the lanternfish. (Occidental College. url: http://www.oxy.edu/sites/default/files/assets/TOPS/Lampfish25.jpg)

Previously, scientists pulled nets behind their boats in a process called trawling in order to capture fish and estimate their populations. This process is not efficient in catching mesopelagic fish and leads to an underestimation of their numbers. Instead of trawling, scientists aboard the Malaspina 2010 used an echosounder, a type of SONAR, to determine the biomass of mesopelagic fish. In this method, the echosounder emits a pulse of sound into the water and records the sound that returns after bouncing off an object. Using sound to weight ratios previously determined in other studies, Irigoien et al. 2014 were able to estimate the mesopelagic fish biomass from the recorded acoustic data. Irigoin et al. 2014 then used food web models to corroborate the estimate given by the acoustic data. Their estimates determined the mesopelagic biomass to be about 10-15,000 million tons, about 10 times higher than previous estimates.

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Caption: Acoustic data collected on the Malaspina 2010. The top of the figure represents the surface of the ocean, and the bottom of the figure represents a depth of 1000 meters. The colors in the figure show where sound bounced off marine organisms and returned to the echosounder. Between 200 and 1000 meters, the organisms are mostly mesopelagic fish. The black triangles indicate the border between ocean basins. AT stands for Atlantic Ocean, IO for Indian Ocean, WP for Western Pacific, and EP for Eastern Pacific. (Irigoien et al. 2014)

Irigoien et al. 2014 also found that mesopelagic biomass is closely tied to the plankton, miniscule, floating organisms of the ocean, that undergo photosynthesis. These photosynthetic plankton form the base of the marine food web, and other, larger plankton consume them. Mesopelagic fish then feed on these herbivorous plankton.

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A photo of diatoms, photosynthetic plankton, under microscope. (Wikipedia. url: http://en.wikipedia.org/wiki/File:Diatoms_through_the_microscope.jpg)

In the open ocean, where nutrients are poor, herbivorous plankton do not efficiently capture photosynthetic plankton. This implies that fish will not efficiently obtain their energy, which ultimately comes from the photosynthetic plankton. However, Irigoien et al. 2014 contest that the transfer of energy to the mesopelagic fish is more efficient in the open ocean because the water is warm and clear, allowing the visual fish to more easily capture their prey. Considering this argument, Irigoien et al. 2014 determined that mesopelagic fish may be using about 10% of photosynthetic plankton for energy.

Irigoien et al. 2014 showed that the biomass of mesopelagic fish, as well as their usage of energy in the open ocean food web, is much greater than previously thought. Due to the impact these two findings would have on ocean ecosystems and chemical cycling within them, scientists must make further and more accurate investigations regarding the mesopelagic fish community.

 

References:

Irigoien, Xabier, T.A. Klevjer, A. Røstad, U. Martinez, G. Boyra, J.L. Acuña, A. Bode, F. Echevarria, J.I. Gonzalez-Gordillo, S. Hernandez-Leon, S. Agusti, D.L. Aksnes, C.M. Duarte, S. Kaartvedt (2014) Large mesopelagic fishes biomass and trophic efficiency in the open ocean. Nature Communications 5, Article number: 3271 doi:10.1038/ncomms4271