Effects of temperature and red tides on sea urchin abundance and species richness over 45 years in southern Japan

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By Nicole Suren, SRC intern

Between 1963 and 2014, scientists in Japan have conducted 45 years of near continuous monitoring of the abundance (number of individuals), species richness (number of species), and developmental abnormalities of the sea urchins around Hatakejima Island. Hatakejima Island has been a marine protected area since 1968, meaning that humans are forbidden from harvesting sea urchins in the area. Removing fishing pressure makes this area the ideal study site to examine the effect of abiotic factors such as sea surface temperature and red tide events on sea urchin population dynamics, which is important since echinoderms (the family containing sea urchins) are often keystone or dominant species in an ecosystem.

Figure 1. Location of Hatakejima Island within Tanabe Bay, Japan. (Source: Ohgaki et al., 2018)

Urchin populations near Hatakejima Island were monitored using three complementary methods. The first was a quadrat study, where the urchins in a permanent underwater quadrat were counted once every year. The second was a coastal survey, where a more general sea urchin count was conducted all along the coast of Hatakejima Island six times total. The third was a developmental assay, where eggs and sperm were collected, fertilized in vitro, and the resulting embryos were monitored for early developmental abnormalities. Overall, the scientists found that the sea surface temperature increased over thirty years, and that developmental abnormalities coincided with the occurrences of red tides.

Figure 2. Population trends of the three most common species of urchin from the study over time. (Source: Ohgaki et al., 2018)

Red tide events, temperature, and ocean currents were found to be closely related to the abundance of the three most common species of urchin: H. crassispina, E. moralis, and Echinometra spp. Exact effects varied depending on species, but red tide events were found to decrease abundance (likely due to the developmental disruption of urchin larvae), while warmer temperatures and proximity to the Kuroshiro current had positive effects on abundance and species richness.

Although this population of sea urchins is not subject to fishing pressure, it is far from unaffected by humans. An increased incidence of red tide events in the area may be attributable to an increase in aquaculture nearby. Furthermore, chemicals like tributyltin (TBT) and other organotin compounds used in fish nets and ships are being introduced to the water, which may also have negative developmental effects that decrease population size. In addition to the other human effects, anthropogenic climate changes also affect urchin abundance and species richness in this area because of their dependence on a particular temperature range. Studies like this one are essential to determining the full extent of human impacts on ecosystems, and should continue to be employed so we can decide how best to mitigate those impacts (Ohgaki et al., 2018).

Work Cited

Ohgaki, S. I., Kato, T., Kobayashi, N., Tanase, H., Kumagai, N. H., Ishida, S., … Yusa, Y. (2018). Effects of temperature and red tides on sea urchin abundance and species richness over 45 years in southern Japan. Ecological Indicators, (January), 0–1. https://doi.org/10.1016/j.ecolind.2018.03.040

Shifted Baselines Reduce Willingness to Pay for Conservation

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By Molly Rickles, SRC intern

With climate change causing negative consequences for almost every ecosystem on earth, now it is more important than ever to fund conservation efforts to restore these extremely important environments. However, many people are unaware about the current state of these critical environments, which may affect their willingness to contribute to these important causes.

In this article, McClenachan et al. (2018) studied whether an individual’s willingness to pay for conservation efforts was affected by their perception of the current health of the environment, which is generally an understudied topic. The researchers used the concept of shifted baselines, or a reduction in expectations of the natural environment over time, to determine if people’s perception of the state of the environment was flawed. It has been previously stated that the public does not understand the baseline for coral reef health, which means that they have no comparison to today’s reefs. This is important to understand for conservation efforts, so that researchers can understand how the public gets engaged in these issues.

To answer their questions, the researchers conducted a survey of residents in Okinawa, Japan, to determine how they viewed change in coral reef ecosystems. It was found that respondents understood that there was a decline in coral reef health, but that the reasons for this decline were unknown. 67% of respondents were able to identify at least one component of decreased health of coral reefs. It was also found that respondents were more willing to pay for the creation of an MPA to solve these problems rather than donating to other conservation efforts, with the average donation being $142.22 annually. (Image 1) The researchers concluded that shifted baselines for reef health did affect willingness to pay for conservation, and that respondents that perceived a decline in reef health were willing to pay more than double than someone who did not understand this decline in health. This research shows the importance of documenting long-term change in ecosystem health, so that the results can be communicated to engage the public in these issues. With a stronger public engagement, people will be more willing to contribute to conservation efforts, which will help raise awareness and funds for these extremely important issues.

Image 1. This table shows how willingness to pay varies for different problems associated with declining reef health. Respondents had the highest willingness to pay for the creation of an MPA (Source: McClenachan et al. 2018)

Image 2. This graph shows the difference between willingness to pay when respondents understand that there are declines in ecosystem health versus when they believe the current state of the ecosystem is normal (Source: McClenachan et al. 2018).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Works Cited

McClenachan, L., Matsuura, R., Shah, P., & Dissanayake, S. T. (2018). Shifted Baselines Reduce Willingness to Pay for Conservation. Frontiers in Marine Science , 5. doi:10.3389/fmars.2018.00048

2018 SRC Accomplishments

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UM SRC had a productive 2018. Here are some of the highlights we are proud to share with you.

  • We published seven research papers in scientific journals. These papers ranged in scientific topics from studying the effects of shark removals on fish communities to evaluating the effects of climate variability on great white shark hunting.
  • Two of our research papers were featured on the covers of scientific journals, viewed below.

 

 

 

 

 

 

 

 

 

 

  • We conducted over 100 field research trips out of Miami supporting our ongoing shark projects. Additionally, we conducted field research in Galapagos, Bahamas and South Africa.
  • Our team brought over 1,200 Citizen Scientists, mostly school kids, on our research vessels to participate in our hands-on shark science. These participants were of diverse origins, representing 42 countries and another 42 states within America.
  • We were honored to host “Make A Wish Foundation” on several trips to help grant children wishes to tag sharks.
  • We were again proud to run our special F.I.N.S trips (Females in the Natural Sciences), providing inspirational research experiences to young girls.
  • This past year our team tagged and sampled 441 different sharks of 12 different species, including 34 great hammerheads and 57 blacktip sharks. The largest shark we tagged was a 394 cm tiger shark and the smallest was a 54 cm nurse shark.
  • Our team was able to satellite tag 22 sharks, including tigers, sandbars and blacktips as well as acoustically tag another 15 sharks, including nurse and great hammerhead.
  • Our SRC team spoke to thousands of people in various outreach events, including exhibiting a booth at the Tortuga Music Festival and traveling to Ohio to speak to high schools.
  • Our team presented scientific talks at several national and international conferences, such as the International Society of development and Comparative Immunology. SRC Director Dr. Neil Hammerschlag also presented a keynote address at both Shark International Scientific Conference in Brazil and the Morris Kahn Marine Research Station in Israel.
  • Our research reached millions of people through exposure in prominent media outlets, including three shows on Discovery Channel’s Shark Week (Monster Tag, Shark Tank meets Shark Week, Tiger Shark Invasion).
  • We held our second annual Summer Research Program, where college students from across North America spent several intense weeks with us in the field and laboratory conducting research.
  • We spent a month in the Dry Tortugas National Park conducting shark surveys of this amazing protected area.
  • Several SRC students defended their thesis, including MS student Robbie Roemer and MPS student Andriana Fragola. We wish them all the best.

 

We are grateful to our active funders and contributors, especially the Batchelor Foundation Inc., the Alma Jennings Foundation, Rock the Ocean Foundation, Herbert W. Hoover Foundation, William J. Gallwey, III, Cannon Solutions America, H.W. Wilson Foundation, the Disney Conservation Fund, Heffner Fund, Interphase Materials, Hook & Tackle, 360 Destinations, L2 Platforms, Ruta Maya Coffee, NOAA, Vineyard Vines, and all generous individuals and groups who have Adopted a Shark.

Directed by Dr. Neil Hammerschlag, the Shark Research & Conservation Program (SRC) at the University of Miami conducts cutting-edge shark research while also inspiring scientific literacy and environmental ethic in youth through unique hands-on field research experiences. To impact an even larger audience from across the globe, SRC continues to use a variety of online education tools, including social media, blogs, educational videos and, online curricula. To learn more, visit www.SharkTagging.com

Thanks to the SRC team, collaborators, and supporters for another incredible year, and let’s make 2019 even better.

 

Global Fisheries and the Growth of Greenhouse Gas Emissions

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By Samantha Orndorff, SRC intern

Global fisheries have long been fundamental in molding cultural identities, maintaining economic sustainability, and providing a reliable source for food production. The distribution and production of food, such as that generated from fisheries, is responsible for a quarter of anthropogenic greenhouse gas (GHG) emissions (Parker et. al 2018). As climate change issues become more paramount, it is imperative that systems of emission are studied to develop management strategies and initiatives to mitigate environmental impact. Fisheries is typically an energy-intensive operation that produces the majority of its emissions directly from burning fossil fuels. A recent study conducted by the Institute for Marine and Antarctic Studies analyzed fuel use data from a Fisheries Energy Use Database in order to quantify fuel input and greenhouse gas emissions produced by the global fishing fleet from 1990-2011. Despite the fact that harvest has remained relatively stable over the past two decades, researchers have found that GHG emissions from world fisheries has increased by 28% from 1990 to 2011.

The countries with the largest national fishing fleets are China, Indonesia, Vietnam, the United States, and Japan. In 2011 approximately 49% of total fishery GHG emissions came solely from the contributions of the five aforementioned countries (Figure 1). Emissions by fishing sector vary considerably based upon targeted species class. For example, crustacean fisheries such as those targeting lobster and shrimp harvest a smaller volume than that of a small pelagic fisheries targeting menhaden which are easily caught. Crustacean fisheries tend to account for a larger percentage of fishery GHG emissions because of the considerable amount of fuel required to target such high-input species. In fact, much of the overall increase in emissions from 1990 to 2011 can be attributed to changes in catch composition, with crustacean catch rates increasing by 60% over two decades (Parker et. al 2018). Thus, the GHG emissions from Asian fishing fleets are much more substantial than European and American fishing fleets given that Asian countries disproportionately target crustaceans whereas Europe and the Americas are primarily comprised of low-input small pelagic fisheries.

Figure 1. GHG emissions in 2011 for each national fishing fleet, up to the point of landing in thousands of tons of carbon dioxide (thousand t CO2-eq) (Parker et. al 2018).

When analyzing the global GHG emissions from other sources of animal protein, such as that of pork, beef and lamb, products derived from marine fisheries for human consumption have significantly lower GHG emissions (Figure 2). It is hypothesized that if fish landed for non-food consumption, such as those used in meal and oil production for aquaculture and livestock, were directed for human consumption than total fisheries emissions would be “lower than every other major source of animal protein” (Parker et. al 2018). Furthermore, global emissions from agriculture and livestock production amounted to 5 billion tons of carbon dioxide in 2011 whereas emissions from marine fisheries only amounted to 179 million tons of carbon dioxide.

Figure 2. Carbon footprint of fishery-derived products for human consumption in 2011 compared to other sources of animal protein (Parker et. al 2018).

Proposed strategies to mitigate GHG emissions from global fisheries include rebuilding fishery stocks and reducing quotas so that the amount of fuel utilized by national fleets can be reduced. Short-term adaptations to improve emission reductions are using more selective fishing times and locations to optimize landings and fuel use. Further and continued research will also aid in creating a more long-term, dynamic and comprehensive solution for studying the relationship between global fisheries and total greenhouse gas emissions.

Work Cited

Robert W. R. Parker, Julia L. Blanchard, Caleb Gardner, Bridget S. Green, Klaas Hartmann, Peter H. Tyedmers & Reg A. Watson. April 2018. Fuel use and greenhouse gas emissions of world fisheries. Nature Climate Change 8:333-337.

Small Gastropods Have A Larger Impact on Corals Than Expected

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By Delaney Reynolds, SRC intern

Logically, one might think that as a population of predators increases, the population of its prey decreases. This has been found to hold true for all species, including corals and their predators (corallivores). Larger, more recognizable corallivores, such as the crown-of-thorn sea star and horn drupe snail, can very negatively impact the composition and tenacity of corals. However, little is known about the impact that smaller corallivores, such as the Coralliophila violacea (violet coral shell snail), can have on coral species and habitats.

Figure 1. The Fiji Islands & C. violacea Density: Three fished areas and MPAs on the south coast, Coral Coast, of Viti Levu, Fiji were surveyed for this analysis. The violin plots depict the density of the C. violacea snails in each MPA and fished area. (Image Source: Clements, Cody S., and Mark Hay. “Overlooked Coral Predators Suppress Foundation Species as Reefs Degrade.” Ecological Applications, 2018, doi:10.31230/osf.io/hcmzg.)

In a study done by the Georgia Institute of Technology, a combination of observational and manipulative experiments were performed to look at how C. violacea densities and size frequencies, measured as shell height, impacted their common host coral Porites cylindrica’s ability to grow and survive in three different fished areas and Marine Protected Areas (MPAs) of Fiji.

In each of the three MPAs and fished areas, C. violacea densities were found to be 35-fold higher in the fished areas, but snails in the MPAs were significantly larger in size. As densities increased, and thus feeding on P. cylindrica increased, P. cylindrica growth was found to be extremely inhibited, supporting the hypothesis that smaller species can have a large, negative impact on their environments.

The decrease in the effects of C. violacea in MPAs make a concrete argument that MPAs are successful ways of protecting marine wildlife and that more should be created all over the world. Current MPAs are, for the most part, small in scale and while they are effective, larger scale protected areas would increase the protection of all sorts of vulnerable organisms, including vital coral species.

Figure 2. Coralliophila violacea. (Image Source: https://fr.wikipedia.org/wiki/Coralliophila_violacea)

 

 

 

 

 

 

 

 

 

 

The way that C. violacea impacts corals so significantly is by its intrusive method of feeding. When preying upon corals, C. violacea will insert its proboscis, a tube-like structure that aids in feeding, into the coral’s polyps and feed on the nutrients that the coral is transporting. This method is detrimental to the coral as it decreases the amount of nutrients that the coral itself intakes and suppresses its growth.

Keeping an eye on how smaller corallivores are impacting coral ecosystems is crucial because as our planet continues to warm and oceans get more acidic, coral populations become increasingly susceptible to bleaching and extinction, facing threats not only from predators but human induced climate change as well. The combination of these factors could lead to an underwater ecosystem devoid of corals and, in turn, of marine life in general.

Works Cited

Clements, Cody S., and Mark Hay. “Overlooked Coral Predators Suppress Foundation Species as Reefs Degrade.” Ecological Applications, 2018, doi:10.31230/osf.io/hcmzg.

Acoustic Telemetry Analysis of California Gamefish Reveals the Functional Performance of the Wheeler North Artificial Reef

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By Chelsea Black, SRC MS Student

Submerged structures such as ships, steel frames, or boulders placed on the seafloor deliberately to mimic attributes of a natural habitat are known as artificial reefs (ARs). Since the development of the National Fishing Enhancement Act of 1984, most AR construction in the United States has been focused on enhancing fishery resources and opportunities (Logan & Lowe 2018). These ARs provide new habitat for both fish and benthic organisms to colonize, which increases food resources and overall fish biomass. However, to establish reef productivity for mobile species it is pertinent to know when and for how long species are resident to a reef, which has historically been overlooked by previous AR studies.

The largest constructed rock reef in the US, the Wheeler North Artificial Reef (WNAR) off the coast of San Clemente in the Southern California Bight, was built by the Southern California Edison Company (SCE) as mitigation for the loss of the San Onofre Kelp Bed after discharged cooling water from a nuclear generating station resulted in restricted giant kelp growth and subsequently the loss of species diversity (Figure 1). For SCE to receive mitigation credit, WNAR must either meet or exceed the abiotic and biotic performance standards relative to community performance from two nearby natural reefs, the San Mateo Kelp Bed (SMK) and the Barn Kelp Bed (BK).

Figure 1. Construction of the WNAR [Source: www.ucsb.edu].

In a recent study, Logan & Lowe (2018) examined the movement patterns of three economically and ecologically important fishes, the kelp bass (Paralabrax clathratus), the barred sand bass (P. nebulifer) and the California sheephead (Semicossyphus pulcher) within WNAR. 195 fish were captured, tagged with acoustic transmitters, released, and monitored by underwater receiver stations for a study period of two years to determine residency indices (Figure 2). When examining these indices, the authors concluded kelp canopy surface area was the single environmental parameter that explained the most variation in residency. This makes sense considering previous research demonstrates that artificial structures with high vertical relief provide important habitat conditions, including refuge from predators, for many species (Martin & Lowe 2010).

Figure 2. Locations of acoustic receivers and neighboring natural reefs [Logan & Lowe 2018].

Figure 3. From top to bottom: California sheephead, kelp bass, and barred sand bass [Source: Wikimedia Commons].

 

 

 

 

 

 

 

 

 

 

 

 

 

After analyzing movement patterns of the tagged fish across WNAR, SMK and BK, this study suggests that during favorable conditions fish were highly resident to WNAR and demonstrate that it is currently functioning similar to the surrounding natural reef habitats, effectively reaching the set performance standards. In addition, the results reveal that future AR management plans in California would be most successful when implementing structures that are ideal for giant kelp growth to aid in increased species diversity in abundance by providing an ideal habitat for important species.

Works Cited

Logan, R. K., & Lowe, C. G. (2018). Residency and inter-reef connectivity of three gamefishes between natural reefs and a large mitigation artificial reef. Marine Ecology Progress Series, 593, 111-126.

Martin CJ, Lowe CG (2010) Assemblage structure of fish at offshore petroleum platforms on the San Pedro Shelf of southern California. Mar Coast Fish 2:180−194.

Climate vulnerability and resilience in the most valuable North American fishery

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By Chris Schenker, SRC intern

Lobster could be considered one of the most important U.S. fisheries, comprising over $1.5 billion in landed value between the U.S. and Canada in 2015. However, lobster harvests are susceptible to fluctuations in water temperature caused by global climate change. Recent warming of the northwest Atlantic coupled with different fisheries management approaches in the Gulf of Maine (GoM) and southern New England (SNE) led to record breaking landings in the GoM and collapse of the lobster fishery in SNE. In this paper, Le Bris et al. (2018) examine why the GoM’s focus on protecting large lobsters allowed it to capitalize on warming waters while SNE fisheries suffered.

Figure 1. Lobster traps in a stack

Increased ocean temperatures have impacted the two regions in different ways. Warmer waters in SNE have been linked to decreased juvenile habitat and higher rates of epizootic shell disease, while warmer waters in the GoM have been linked to increased juvenile habitat and a loss of large bodied predators. Fisheries management approaches also differ between the two regions; the GoM is divided into smaller “local lobster zones” that are managed by fishing effort controls and size limitations instead of the quota system. To examine the effects of these management approaches and climate change more closely, the authors created a model integrating the impacts of ocean warming, fishing pressure, and predator density on lobster population dynamics across a wide range of habitats.

Figure 2. A man harvesting a lobster.

This model estimated that mean abundance increased by 515% in the GoM from 1985 to 2014, while mean abundance in the SNE stock declined by 78% from 1997 to 2014. Increased water temperatures was the largest factor driving this divergence, leading to a greater production of 1 year old lobsters per egg in the GoM but exceeding the thermal optimum for lobster recruitment in SNE. Removal of large predators in the north and shell disease in the south further exacerbated these trends. Furthermore, the V-notching program to preserve reproductive females is mandatory in the GoM but voluntary and less widespread in SNE. Without V-notching in the GoM, the model estimated only a 242% increase in lobster stock, whereas if more stringent conservation methods were in place in SNE, the model estimated a decrease of only 57% instead of 78%. Looking forward until 2050, the model predicted a decline in GoM stock due to temperature fluctuations that could be mitigated by continued protection of reproductive females, whereas SNE stocks could recover somewhat due to increased conservation but never back to mid-1990’s levels.

Figure 3. Lobster recruitment in the New England area.

There are limits, however, to be aware of with this model, such as the coarse resolution of climate models, an assumed independence of lobster population units, a lack of consideration for rapid evolutionary adaptation, and the assumption that temperature is the only climatic stressor on lobster populations. Despite these limitations, Le Bris et al. conclude that proactive fisheries management strategies based on biological principles can lessen negative ecosystem changes and increase positive ones. However, reliance on a single fishery is risky, and diversified economic opportunities should be adopted in the uncertain face of future climate change.

 

 

 

Work Cited

Le Bris, A., Mills, K. E., Wahle, R. A., Chen, Y., Alexander, M. A., Allyn, A. J., … Pershing, A. J. (2018). Climate vulnerability and resilience in the most valuable North American fishery. Proceedings of the National Academy of Sciences. doi:10.1073/pnas.1711122115

Fading Corals: The Effect of Anthropogenic Climate Change on Coral Reefs

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By Konnor Payne, SRC intern

Due to the dramatic ecological changes caused by humans to the Earth, a new period has been named after humans called the Anthropocene. In the Anthropocene, it appears, the next change is to the Earth’s coral reefs. The number one cause of stony coral (Reef-building coral) loss is the warming of waters due to anthropogenic global warming (Causey, 2001; Manzello, 2015). As technology and industry continue to accelerate, the issue of global warming will only worsen and thus the coral reefs shall continue to suffer.

Figure 1. The coral is bleached and has had its zooxanthellae expelled. This can occur to any reef-building coral that is under too much stress from outside influences. The coral is starving without the photosynthetic symbiote and is likely to starve to death. (Source: “KeppelBleaching.” Wikipedia.org, 22 Aug. 2011, en.wikipedia.org/wiki/File:Keppelbleaching.jpg)

Corals are tiny soft-bodied organisms related to sea anemones that build a calcium carbonate skeleton around themselves. Within their bodies is a symbiotic dinoflagellate, called zooxanthellae, that photosynthesizes to provide the corals with organic matter. Bleaching is when a coral colony becomes so overly stressed that the zooxanthellae are expelled resulting in a lack of color. In this bleached state, the coral begins to starve and is likely to die. In the Florida Keys Reef Tract (FKRT) increasing sea surface temperature has led to an increase in the number of major bleaching events (Van Hooidonk et al., 2013), leading to the loss of 40% of stony corals since 1996 causing an ecological shift towards octocorals, macroalgae and sponges (Ruzicka et al., 2013).

In May of 2015 and 2016, researchers excavated coral skeletal cores from the two most critical reef-building corals, Siderastrea sidereal and Pseudodiploria strigose, in the FKRT to examine skeletal density, growth and calcification rates. Using X-rays and a 3D modeling program, (Horos V2.0.2) the layers of coral grown each year could be analyzed accurately pixel by pixel. The researchers found that the skeletal density remained consistent up until the last century, in which overall skeletal density significantly decreased, but extension and calcification rates did not change significantly compared to their respective biological history (Rippe, 2018). Both species of coral have been able to sustain baseline growth rates despite recent bleaching events and chronic ocean warming. This suggests that corals of the subtropical environment are likely to have a buffer to the effects of ocean warming and the underlying cause of reduction in the skeletal density is levels of aragonite saturation in the water (Rippe, 2018). The study suggests that further research into the carbonate chemistry of the FKRT is required to understand how heavily aragonite saturation affects skeletal density.

Figure 2. The coral skeletal core has distinctive bands to distinguish skeletal density, extension and calcification rates over the years. By comparing past to future bands, the anthropogenic effects on the coral can be visually determined. (Source: Felis 2005).

Works Cited

Causey, B. (2001). Lessons learned from the intensification of coral bleaching from 1980–2000
in the Florida Keys, USA. Paper presented at the Proceedings of the Workshop on Mitigating Coral Bleaching Impact through MPA Design. Honolulu, Hawaii.

Felis, Thomas. “Paleoclimatology: Climate Close-Up.” NASA Earth Observatory, 23 Dec. 2005, earthobservatory.nasa.gov/Features/Paleoclimatology_CloseUp/paleoclimatology_closeup_2.php.
Manzello, D. P. (2015). Rapid recent warming of coral reefs in the Florida Keys.
Scientific Reports, 5.

Rippe, John. (2018). Corals sustain growth but not skeletal desnity across the Florida Keys Reef
Tract despite ongoing warming. Primary Research Articles.

Ruzicka, R., Colella, M., Porter, J., Morrison, J., Kidney, J., Brinkhuis, V., … Meyers, M.
(2013). Temporal changes in benthic assemblages on Florida Keys reefs 11 years after the 1997/1998 El Niño. Marine Ecology Progress Series, 489, 125-141.

Van Hooidonk, R., Maynard, J., & Planes, S. (2013). Temporary refugia for coral reefs in a
warming world. Nature Climate Change, 3(5), 508-511.

Albatross-born loggers show feeding on deep-sea squids: implications for the study of squid distributions

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By Gaitlyn Malone, SRC intern

Deep-sea squids are considered to be an important prey source for many top marine predators including fish, marine mammals, and seabirds (Clarke, 1996). However, despite their importance in marine food web structures, there is relatively little known about the biology and ecology of these squids, due to lack of observations, as well as limited knowledge of when, where, and how top predators prey on them (Nishizawa et al., 2018). Albatrosses are just one seabird species that feed mainly on squid, including those deep-sea dwelling species. Since albatrosses feed by capturing prey on the surface of the water, how they are able to obtain deep-sea squid has long been a mystery.

Figure 1. Laysan albatross (Phoebastria immutabilis) near Kauai, Hawaii (Dick Daniels, Wikimedia)

Multiple methods for accessing these squid have been hypothesized including feeding on squid that are dead and floating after spawning, those discarded from fishing vessels and longliners, those regurgitated by cetaceans, those that are living and come to the surface at night, or those that are alive and aggregate at the surface near productive ocean fronts (Rodhouse et al., 1987; Thompson, 1992; Clarke et al. 1981; Imber, 1992; Xavier et al., 2004). A recent study examined the post-spawning floater, fishery-related, and oceanic front hypotheses using Laysan albatrosses that were breeding on Oahu, Hawaii (Nishizawa et al., 2018). Laysan albatrosses were determined to be a suitable species to test these hypotheses due to the fact that they feed on both on deep-sea dwelling squid species and Argentine squids (Illex argentines), which are often used as bait in the swordfish longline fishery in Hawaii. In order to perform this analysis, 38 birds that were raising chicks were fitted with GPS-loggers and camera-loggers during the early chick-rearing period in February and March of 2015. The GPS-loggers were positioned on the backs of the birds, while the camera-loggers were placed on either the back or the belly depending on whether the bird was brooding chicks. Images were only collected by the cameras during daylight hours and were used to identify any squid species the birds preyed on, whether those squid were alive or dead, and whether they were whole or fragmented. Camera images were also used to reveal if fishing vessels or cetaceans were present in the area.

Figure 2. Images of squids recorded by the camera-loggers attached to Laysan albatrosses (Nishizawa et al., 2018)

In total, 26,068 images were obtained from 26 trips of 20 birds. Of those images, squids were visible in 23 images which corresponded to 16 predation events from 7 trips of 7 birds. Fishing vessels were found to be present in 69 images. All of the squids observed from the camera-loggers were dead and floating at the surface of the water, with ten of the squids being found in fragments while the other six were whole. Since many deep-sea dwelling squid species spawn and then die, it is possible that some of the squids present in the recorded predation events were the result of spawning mortalities. Although fishing vessels were observed, none were present in the images obtained during feeding events and the squids that were preyed upon were much larger than bait species. Therefore, these predation events are most likely not related to fishing occurring within the area. Overall, it was determined that Laysan albatrosses tend to feed opportunistically and do not tend to concentrate their efforts to a particular area. Through the use of GPS and camera-loggers, this study demonstrates how beneficial these devices can be in collecting information on the distribution of deep-sea squid and the significant role they play in the diet of marine predators.

Works Cited

Clarke, M.R. 1996. Cephalopods as prey. III. Cetaceans. Philosophical Transactions of the Royal Society B 351: 1053-1065.

Clarke, M.R., J.P. Croxall, P.A. Prince. 1981. Cephalopod remains in the regurgitations of the wandering albatross Diomedea exulas L at South Georgia. British Antarctic Survey Bulletin 54: 9-21.

Imber, M.J. 1992. Cephalopods eaten by wandering albatrosses (Diomedea exulans L.) breeding at six circumpolar localities. Journal of the Royal Society of New Zealand 22(4): 243-263.

Nishizawa, B., T. Sugawara, L.C. Young, E.A. Vanderwerf, K. Yoda, Y. Watanuki. 2018. Albatross-born loggers show feeding on deep-sea squids: implications for the study of squid distributions. Marine Ecology Progress Series 592: 257-265.

Rodhouse, P.G., M.R. Clarke, A.W.A. Murray. 1987. Cephalopod prey of the wandering albatross Diomedea exulans.Marine Biology 96(1): 1-10.

Thompson, K.R. 1992. Quantitative analysis of the use of discards from squid trawlers by black-browed albatrosses Diomedea melanophris in the vicinity of the Falkland Islands. Ibis 134: 11-21.

Xavier, J.C., P.N. Trathan, J.P. Croxall, A.G. Wood, G. Podesta, P. Rodhouse. 2004. Foraging ecology and interactions with fisheries of wandering albatrosses (Diomedea exulans) breeding at South Georgia. Fisheries Oceanography 13(5): 324-344.

Gravity of human impacts mediates coral reef conservation gains

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By Brenna Bales, SRC intern

Communities around the world depend on coral reefs for their livelihood, for tourism, and for protection against coastal degradation. With an increasing human population comes increasing human impact on these coral reefs and a decrease in the ability of a reef to provide the benefits listed above. Direct human impacts include overfishing, polluting the reef with trash or chemicals, and dredging; however, there are indirect human impacts such as anthropogenic climate change. Greenhouse warming affects ocean temperature which can stress corals (Jokiel 2004), and ocean acidification from carbon uptake can decrease the ability of corals to build limestone foundations (Langdon et al, 2000).

In Cinner et al’s analysis, the magnitude of human impact on of 1,798 tropical reefs in 41 nations/states/territories was described and quantified. In order to quantify this impact, the authors used a social science metric termed “gravity”, which has been used from economics to geography. For the adaptation to an ecological analysis, the gravity of human impact was measured as a function of how large and how far away a population of humans was to a certain coral reef (Figure 1). In each location, the status of reef management ranged from openly fished (little to no management), to highly protected marine reserves where fishing is completely prohibited.

Figure 1. The authors’ interpretation of “gravity” as a function of the population of an area
divided by the time it takes to travel to the reefs squared. (Cinner et al, 2018)

Two expected “conservation gains” (differences in the progress of a coral reef ecosystem when protected versus unprotected) in all regions were analyzed as to how they are influenced by human activity. The first was targeted reef fish biomass (species usually caught in fisheries) and the second was the presence of top predators within the ecosystem. Conservation gains can be beneficial to both people and ecosystems; When the health of a protected coral reef improves, it might drive new recruits and help re-establish other nearby reefs that are fished more. The authors hypothesized that the target conservation gains would decline with increasing gravity in areas where fishing was allowed, but that marine reserves would be less susceptible to these gravity influences.

Analysis of visual fish count data collected from 2004-2013 showed that gravity strongly predicted the outcomes for fish biomass in a reef ecosystem. Biomass in marine reserves showed a less steep decline with increasing impact as compared to openly fished and restricted areas (Figure 2). This was due to an unforeseen relationship between gravity and the age of a marine reserve. In high-gravity areas, older reserves contributed more to fish biomass when compared to low-gravity areas. These older reserves have had more time to recover after periods of high fishing stress. Even in the highest-gravity reserves, fish biomass was about 5 times higher than in openly fished areas. Top predators were only encountered in 28% of the reef sites, and as gravity increased, the chance of encountering a top predator dropped to almost zero. Overall, highly regulated marine reserves in low-gravity situations showed the highest biomass levels, and the greatest chance of encountering a top predator.

Figure 2. Modeled relationships showing reef fish biomass declines with gravity increases by
regulation type. Openly fished (red), restricted (green), and high-compliance marine reserves
(blue). (Cinner et al, 2018)

Four explanations for the decrease of fish biomass and top predator encounters were (i) human impact in the surrounding area of a marine reserve affecting the interior, (ii) poaching effects, (iii) life history traits of top predators making them susceptible to even minimal fishing stress, and (iv) high-gravity reserves being too young or too small for drastic improvement. The fourth explanation was further analyzed, where large versus small reserves were compared. Not surprisingly, larger reserves had higher biomass levels and top predator encounter probabilities. Lastly, the ages of the reserves were examined. The average reserve age was 15.5 years compared to older reserves (29 +/- years), and older reserves had a 66% predicted increase in biomass levels. Analysis of the likelihood of encountering a top predator was less definitive, suggesting high-density areas, no matter the age, reduce this probability greatly.

Ecological trade-offs such as high-gravity reserves being beneficial for conservation gains like reef fish biomass, but not so much for top predators, are important to consider. Top predators can face more fishing stress even in remote areas due to their high price in international markets, such as sharks for their fins, explaining the observed difference in low-gravity fished areas versus low-gravity marine reserves. Overall, when aiming to create an effective marine reserve or even regulations that aid in conservation gains, it is imperative to consider the gravity of human impact in the surrounding areas. How the impacts of gravity can be reduced is critical as populations grow along coastlines and climate change stressors increase as well. Multiple forms of management will most likely provide the most benefit to stakeholders (Figure 3) and the ecosystem.

Figure 3. A fisherman in the town of Paje, Tanzania takes his boat out behind the reef barrier to
catch a meal. Stakeholders are an important part in considering reef management decisions, as
millions of people rely on the reefs for their meals just as this fisherman.
(https://commons.wikimedia.org/wiki/File:Fisherman_in_Paje.jpg)

Works Cited

Langdon, C., Takahashi, T., Sweeney, C., Chipman, D., Goddard, J., Marubini, F., Aceves, H., Barnett, H. and Atkinson, M.J., 2000. Effect of calcium carbonate saturation state on the calcification rate of an experimental coral reef. Global Biogeochemical Cycles, 14(2), pp.639-654.

Jokiel, P.L., 2004. Temperature stress and coral bleaching. In Coral health and disease (pp. 401-425). Springer, Berlin, Heidelberg.