The Impact and Epidemic of Overexploitation on Chambered Nautilus Populations

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By Sianna Raquel Vacca, SRC intern

The era of one of the cephalopod’s oldest family members and elusive living fossil, the chambered nautilus, may be coming to an end. This prehistoric species has remained unchanged for over 400 million years and is a native of the tropical, deep-water habitats in the Indo-Pacific region. They are closely related to the other cephalopods such as octopus, squid, and cuttlefish and shares various distinguishing characteristics with its’ modern relatives such as jet propulsion (which allows them to attain speeds of about two knots) and the use of their strong beaks to prey on and crush crustaceans. Chambered nautiluses have retractable tentacles in numbers far surpassing 90, which suitably equip them to be deep-sea scavengers and opportunistic predators. While their eye-sight is poor and merely permits them to discern varying light concentrations, this species is greatly dependent upon their sense of smell while hunting.

Figure 1: Chambered nautiluses can extend their tentacles deep into various substrates to search for small, dead marine organisms, such as shrimp. (Source: Flickr).

Although they are biologically similar to other living cephalopods in a handful of ways, the nautilus is a specifically unique species with distinguishable features setting them apart from their relatives. “Most obvious, nautiluses possess the ancestral trait of an external shell; a shell that has protected them for hundreds of millions of year but is dooming them today” (Barord 2015).

Despite the nautilus species’ historical resilience, proven by their survival through all five major mass extinctions, marine conservationists are fearful that they will not fare as well through the sixth global extinction episode. The crudely unregulated and poorly managed nautilus shell harvest industry is depleting Pacific populations at alarming and consequential rates, further exacerbating the biotic threats posed by overexploitation. Their distinctive coiled and patterned shells are internationally sold as souvenirs, jewelry pieces, and home décor items, to name just a few uses. Since there is no evidence or indication that nautilus fishing is part of a cultural practice or stems from historical relevance, it appears that the demand for these shells is superfluous. While habitat destruction and climate change has been used as part of the argument construct to explain the declining nautilus populations, the shell harvest industry, most prominent in the Philippines and western Indonesia, has proven to be the most influential culprit.

Figure 2: Ornamental nautilus shells are considered to be an international commodity because of their unique, coiled design. The chambers within their shells, as pictured above, actually serve the nautiluses a great physical function by allowing them to either fill or empty these compartments with water to adjust their density. (Source: Pixabay).

DeAngelis (2011) investigated the changes in catch per unit effort (CPUE) in nautilus fishery regions in comparison to an unexploited nautilus population, further proved the impact of overfishing. The paper reports that while an unexploited chambered nautilus population at Osprey Reef, Coral Sea in Australia has remained stable throughout the past twelve years, results from the Philippines show up to 80% declines in reported CPUE from 1980 to the present. This time span consists of fewer than three nautilus generations, indicating that because they are hindered by a slow growth-rate and gradual reproductive output, the chambered nautilus seems to have a low likelihood of recovery or repopulation.

It may seem that this precious, ancient species is doomed to an inevitable extinction within the foreseeable future, however, domestic efforts to starve the shelling industry can have notable impacts. While the United States has historically participated in the nautilus shell trade, a recent recommendation has been submitted to the U.S. Congress from the National Marine Fisheries Service (NMFS) and National Oceanic and Atmospheric Administration (NOAA) to list the chambered nautilus as ‘threatened’ under the Endangered Species Act (ESA). The factual substantiation offered in the aforementioned proposal demonstrates that the survival of this species is in dire need of human intervention, and the protections granted in the Endangered Species Act could potentially reverse the chambered nautilus’ path towards extinction. Defenses for listing the nautilus species as ‘threatened’ under the ESA include:

1) The chambered nautilus serves a greater function alive than that of its hollowed shell.

Chambered nautiluses are part of the complex ecosystem that makes up coral reefs. To avoid predation in the open ocean, these small marine mollusks dwell in reefs for protection. As both an active predator and scavenger, they play a valuable role in their environment.

Additionally, this animal is being harvested for ultimately futile purposes. Unlike some species which are hunted for their meat and act as the primary food source for undeveloped countries, chambered nautiluses are captured for their shells. These shells are then internationally traded and used for aesthetic and nostalgic purposes. The harvest of this species would perhaps be more justifiable if they were being used to prevent some sort of starvation epidemic, but seeing as that is not the case, their current use is unnecessary.

2) This species has already experienced significant population declines.

Due to the excessive chambered nautilus shelling industry in the Philippines, Pacific nautilus populations have notably decreased. While not much is known about these organisms because of how deep in the ocean they live, enough data has been collected to statistically prove that if they continue to be extracted at current rates, they will experience extinction within the foreseeable future.

3) Efforts taken as part of U.S. policy will hopefully encourage other countries to follow suit.

As a global superpower, many nations look to the United States as a model for policy and legislative procedure. While harvesting chambered nautiluses isn’t nearly as prominent of an industry in the U.S. as it is in southeast Asia, formally recognizing that this species is threatened could bring international awareness to this ecological concern. It could encourage other nation-states to institute various policy instruments to protect nautilus populations and promote lasting, world-wide conservation efforts.

This classification could save the chambered nautilus from extinction, albeit directly or indirectly by slowing the rate at which their population declines and allowing for additional measures to be taken.

Works cited

De Angelis, Patricia. “Assessing the Impact of International Trade on Chambered Nautilus.” Geobios, vol. 45, no. 1, 2012, pp. 5–11., doi:10.1016/j.geobios.2011.11.005.

Barord, Gregory Jeff. “On the biology, behavior, and conservation of the chambered nautilus, Nautilus sp.” 

Dunstan, A., et al. “Nautilus Pompilius Fishing and Population Decline in the Philippines: A Comparison with an Unexploited Australian Nautilus Population.” Fisheries Research, vol. 106, no. 2, 2010, pp. 239–247., doi:10.1016/j.fishres.2010.06.015.

Dunstan, Andrew, et al. “Nautilus at Risk,Estimating Population Size and Demography of Nautilus Pompilius.” PLoS ONE, vol. 6, no. 2, Oct. 2011, doi:10.1371/journal.pone.0016716.

Climate Change effects on sea turtles

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By Molly Rickles, SRC intern

Climate change has become an increasing threat to species across the planet. With hotter average temperatures and less predictable weather patterns, humans have undeniably influenced the global climate. The effects of a changing climate are translated to the ocean, where warmer sea surface temperature and rising sea level can alter the marine ecosystem on many levels. These changes can decrease biodiversity and alter the balance of marine ecosystems (Fuentes et al. 2010). These far-reaching effects have extreme consequences for marine life, but some species are impacted more than others. Sea turtles are heavily affected by climate change because of their wide range of habitats (Butt et al. 2016). Since sea turtles lay eggs on beaches but spend their lives in the ocean, they are affected by climate change on both fronts. In addition, climate change may affect survival of juvenile sea turtles, decreasing adult population numbers. Since sea turtles can be widely affected by the far-reaching effects of climate change, it is necessary to implement measures of protection for them. There are ongoing research projects to determine how climate change directly impacts sea turtles and what the best policy options are to combat these effects. This is important because there is little information on how to protect these species from the effects of climate change.

In A, the mean air temperature is shown (black points) against the mean sand temperature (white points) to show how the temperature fluctuates throughout the year. In B, the proportion of nesting by loggerhead turtles for 2005, 2007, 2008, 2009. (Source: Perez, E. A., Marco, A., Martins, S., & Hawkes, L. (2016). Is this what a climate change-resilient population of marine turtles looks like? Biological Conservation, 193, 124-132. doi:10.1016/j.biocon.2015.11.023)

Over the past forty years, sea level has risen at an average of 2mm each year (Butt et al. 2010). This is an alarming statistic especially for low-lying and coastal areas. This is also bad news for sea turtles, which lay their eggs on beaches, which have already been affected by rising sea levels. Beaches are at a high risk for flooding from sea level rise, and when this does occur, the sea turtle eggs are washed away or swamped (Perez et al. 2016). This is especially devastating for endangered species of turtles such as the Hawksbill Turtle or the Australian Loggerhead Turtle, whose numbers are already low and cannot afford a sharp decrease in reproductive output (Butt et al. 2016).

Another major threat to sea turtles is rising sea surface temperature. One of the major effects of climate change is an increase in air temperature, which correlates to an increase in sea surface temperature. This excess thermal stress has especially hard consequences for reptiles, who are exothermic animals that rely on outside temperature to regulate their internal temperature (Perez et al. 2016). An increased sea surface temperature creates a more stressful environment for the sea turtles, but the increased sand temperature has proven to be even more harmful. Since sea turtles lay eggs on beaches, the hotter sand leads to less ideal conditions for laying eggs, which leads to decreased reproductive output. In addition, the sex of the embryos is partially determined by the outside temperature. In this case, a warmer environment leads to a higher percentage of females. It has been estimated that a 2°C increase will lead to a 99.86% female hatching rate (Butt et al. 2016). This, of course, will lead to a very lopsided sex ratio within sea turtle populations, further decreasing the reproductive output and population size.

The image shows all of the nesting sites identified in Australia. This shows that sea turtles have a wide range of habitats. This is beneficial because it allows policy makers to protect certain beaches where sea turtles are known to use for nesting. (Source: Butt, N., Whiting, S., & Dethmers, K. (2016). Identifying future sea turtle conservation areas under climate change. Biological Conservation, 204, 189-196. doi:10.1016/j.biocon.2016.10.012)

All of these threats to sea turtles could have devastating effects on their populations. Decreases in sea turtle populations have already been observed, and most sea turtle species are already on the endangered species list. Due to the fact that sea turtles are dealing with a multitude of threats, it becomes increasingly difficult to find management techniques to combat these issues (Fuentes et al. 2010). Some of the more straightforward strategies deal with the sea turtle’s habitat on land, since it is easier to manage beaches than the open ocean. Since sea turtles rely on certain beaches for nesting, it is possible to protect these areas to preserve the nesting habitat (Fuentes et al. 2010). This has already been implemented in many coastal areas, where nesting sites are blocked off from public use. In addition, many coastal areas have regulations to control nighttime lighting near nesting beaches so the sea turtle hatchlings have a better chance of making it to the ocean. By protecting these important nesting areas, sea turtles will continue to be able to lay eggs safely, and more hatchlings will survive to adulthood. This will lead to an increase in sea turtle population, thus preventing their numbers from decreasing even more rapidly.

In addition to managing habitat on land, it is also important to protect sea turtles in the ocean. One way to do this is to implement marine protected areas in important habitats for the turtles, such as areas where their young mature. However, the main issue affecting sea turtles is climate change, and this must be dealt with at a larger scale. To reduce the overall impact of climate change not only on sea turtles, but every other species, it is necessary to reduce the emissions of greenhouse gases and create a more sustainable way of life. There have already been steps made towards this goal, including the Paris Climate Accord, along with numerous clean air emission standards, but it is not enough. Stricter environmental regulations and environmental conservation education will help reach a more sustainable life, as well as protect sea turtles along with a multitude of other species

References

Fuentes, M., & Cinner, J. (2010). Using expert opinion to prioritize impacts of climate change on sea turtles’ nesting grounds. Journal of Environmental Management, 91(12), 2511-2518. doi:10.1016/j.jenvman.2010.07.013

Butt, N., Whiting, S., & Dethmers, K. (2016). Identifying future sea turtle conservation areas under climate change. Biological Conservation, 204, 189-196. doi:10.1016/j.biocon.2016.10.012

Perez, E. A., Marco, A., Martins, S., & Hawkes, L. (2016). Is this what a climate change-resilient population of marine turtles looks like? Biological Conservation, 193, 124-132. doi:10.1016/j.biocon.2015.11.023

Coral Bleaching of the Great Barrier Reef

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By Delaney Reynolds, SRC intern

Coral reefs are some of planet earth’s most spectacular, diverse and important ecosystems. Our planet’s coral reefs provide important shelter, habitats, and a source of food for many different species of marine organisms. They also act as a critical food source to humans, as well a natural barrier to help protect our coastlines from hurricanes and associated storm surges. Sadly, coral reefs face growing risks including the possibility of extinction from a variety of stresses that leads to coral bleaching.

Figure 1: Coral from which the zooxanthellae has been expelled, causing it to turn white (Image Source: https://en.wikipedia.org/wiki/File:Keppelbleaching.jpg)

Coral bleaching is the process in which zooxanthellae, algae living symbiotically within the coral, are expelled from coral colonies due to a number of factors including an increase in temperature, decrease in pH, exposure to UV radiation, reduced salinity, and bacterial infections. Zooxanthellae provide the coral 30% of its nitrogen and 91% of its carbon needs to the coral host in exchange for a shelter, as well as waste produced by the coral from nitrogen, phosphorus, and carbon dioxide that is required for the algae’s growth (Baird, 2002).

When corals bleach, it effects entire marine communities due to their immense diversity. Fish populations that reside around coral reefs “are the most species dense vertebrate communities on earth, contributing critical ecosystem functions and providing crucial ecosystem services to human societies in tropical countries” (Graham, 2008). Researchers have found that when an ecosystem endures physical coral loss, fish species richness is extremely likely to decline due to their heavy reliance on the coral colony itself (Graham, 2008).

Perhaps the most famous current example of coral bleaching is Australia’s Great Barrier Reef. Scientists have determined that the main cause of Great Barrier Reef coral bleaching is induced thermal stress and that about 90% of the reef has been bleached since 1998 (Baird, 2002). As the corals bleach and temperatures increase, researchers have determined that shark and ray species that live in the area may be vulnerable to these climactic changes.

Figure 2: Exposure of Ecological Groups of GBR Sharks and Rays to Climate Change Factors. This figure displays the vulnerability different elasmobranch species face due to climate change, as well as the specific effects of climate change that they are vulnerable to, in the specific zones of the Great Barrier Reef. (Image Source: Chin et al. 2010)

Most of the Great Barrier Reef is located on the mid-shelf of the ocean floor, the approximate mid-point between the shallower coast of Australia and the continental shelf where the ocean bottom significantly drops in depth. Researchers found that the mid-shelf is the area where most of the shark species studied reside, while most rays dwell in coastal waters or closer to the continental shelf. It was also found that both areas are the susceptible to rising temperature, increased storm frequency and intensity, increasing acidity, current alterations, and freshwater runoff, all being caused by climate change (Chin, 2010). Based on these findings, researchers have concluded that the areas these elasmobranchs live in should be protected and preserved. Species in these highly vulnerable areas should also be monitored and considered for future conservation actions, as many of the shark species are already experiencing the effects of climate change from some of the aforementioned factors.

Typically, sharks are considered some of the strongest animals on earth, and while they have lived on earth for at least 420 million years, they are slow to adapt. This slowness has impeded their ability to survive in our rapidly changing climate. In the near future it will be common to see some species of marine organisms demonstrate plasticity, the ability to adapt to their changing environment, but other species, such as elasmobranchs, are expected to simply distribute to other habitats in search of cooler waters. Even though sharks are a highly vulnerable species to climate change, they sit at the top of the trophic level in many different niches and, thus, wherever they migrate to, it will be easier for them to find food than it would be for other species such as fish or rays. However, this is most likely only the case for adult sharks as embryos and juvenile sharks may be more vulnerable to increased temperatures. For instance, researchers found that the survival of bamboo shark embryos decreased from 100% at current temperatures to 80% under future ocean temperature scenarios and that the embryonic period was also shortened, not allowing the embryo enough time to develop fully (Rosa, 2014).

To decrease the effects of climate change on coral bleaching, corrective and mitigation measures can be taken. By utilizing green energy sources such as implementing solar power or wind power, walking or biking, and driving electric cars, we can reduce our use of fossil fuels and carbon footprint, thus decreasing the amount of carbon dioxide polluting and warming our atmosphere and oceans. While underwater and not always visible, coral reefs are truly a vital part of our ecosystem and need to be cherished and protected for generations to come.

References

Baird, A. H., & Marshall, P. A. (2002, July 18). Mortality, growth and reproduction in scleractinian corals following bleaching on the Great Barrier Reef. Retrieved from https://researchonline.jcu.edu.au/1521/1/Baird_and_Marshall_2002.pdf

Chin, A., Kyne, P. M., Walker, T. I. and McAuley, R. B. (2010), An integrated risk assessment for climate change: analyzing the vulnerability of sharks and rays on Australia’s Great Barrier Reef. Global Change Biology, 16: 1936–1953. doi:10.1111/j.1365-2486.2009.02128.x

Graham, N. A., McClanahan, T. R., MacNeil, M. A., Wilson, S. K., Polunin, N. V., Jennings, S., . . . Sheppard, C. R. (2008, August 27). Climate Warming, Marine Protected Areas and the Ocean-Scale Integrity of Coral Reef Ecosystems. Retrieved from http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0003039

Rosa, R., Baptista, M., Lopes, V. M., Pegado, M. R., Paula, J. R., Trubenbach, K., . . . Repolho, T. (2014, August 13). Early-life exposure to climate change impairs tropical shark survival. Retrieved November 2, 2017, from http://rspb.royalsocietypublishing.org/content/royprsb/281/1793/20141738.full.pdf

Hawaiian Monk Seal Conservation

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By Abby Tinari, SRC intern

Monk seals are warm water species historically residing in the Caribbean, Mediterranean and Hawaii. Now only Mediterranean and Hawaiian populations remain, both of which are critically endangered according to the International Union of Conservation of Nature (ICUN). Hawaiian monk seals have an estimated 1300 wild individuals living around the Hawaiian archipelago.

Figure 1: A juvenile Hawaiian monk seal at French Frigate Shoals. (MarkSullivan, Wikimedia)

In the early 1800s thousands of these seals were hunted for their meat, skin and oil. At the end of the 19th century and early into the 20th, the species was thought to be close to extinction. In 1958, the first beach count of the species was conducted, and surveyors concluded that the Hawaiian monk seal had made a partial recovery (Schultz, Baker et al. 2011). This was short lived. The population has since declined and is declining 4% per year on some Hawaiian Islands. These declines are due to a low juvenile survival rate because of starvation, shark predation, marine debris entanglement, by catch, sea-level rise and intra-specific male seal aggression (Schultz, Baker et al. (2011) & Norris, Littnan et al. (2017)). These seals have been consistently monitored since the 1980s when they were placed on the endangered species list. Scientists started going to pupping grounds to tag, sample and identify individuals (Baker and Thompson 2007). The Baker and Thompson (2007) study observed that the Hawaiian monk seal population is senescing, or growing older and less reproductive. Females give birth to a single pup after a 10-11 month gestation period. She then nurses the pup for 5-6 weeks. So, reproduction rates are relatively low to begin with, plus a low survival rate in the first 2 years of life is hurting the populations long term growth rate (Baker and Thompson 2007). Norris, Littnan et al. (2017) indicated that one of the main threats to young seals, less than 2 years old, is the lack of available prey.

Figure 2: The Hawaiian Archipelago, with demarcations showing the extent of the Northwestern and main Hawaiian Islands. Place names of most islands and atolls where Hawaiian monk seals (Neomonachus schauinslandi) occur are noted. (Baker, Harting et al. 2017)

With now almost 40 years on the ICUN’s endangered and critically endangered list there have been attempts at conservation. Two of these methods include translocation and vaccination. Translocation was used in the past with mixed results, some seals survived while others unfortunately did not. Schultz, Baker et al 2011 write about using genetics among other factors to see if a population is more likely to have long term success with translocation. If subpopulations have a wide genetic diversity and many genetic differences between them, then translocation may not be the best solution and could potentially produce unfit individuals. On the other hand, less genetically diverse subpopulations would have a higher success rate with fit individuals through translocation. Hawaiian monk seals were thought to have had separate subpopulations throughout the archipelago, due to the spatial distance between the islands. After genetic analysis of over 1800 individuals over 13 years Schultz, Baker et al 2011 found that the subpopulations are genetically not statistically different, they in fact, comprise of a single population. This is good news for translocation, it could be an effective means of conservation if the new location is suitable. Norris, Littnan et al. (2017) supports Schultz’s findings. Weanling seals just learning how to hunt on their own were translocated to a new island that had an abundant amount of food and few seals. The habitat was also ideal, providing adequate depth, and bottom type for both young and adult seals to hunt successfully. There was a small difference between the resident and translocated seal survival into adulthood. This survival rate is an essential marker for a translocation program. Translocation is a great way to increase numbers and repopulate suitable locations, but other conservation methods may be equally, if not more, important to a population’s survival.

Figure 3: Stacie Robinson, a biologist with the National Oceanic and Atmospheric Administration in Honolulu, vaccinates a Hawaiian monk seal basking on the island of Oahu. (Malakoff 2016)

For the first time ever, a wild population of marine mammals is receiving a vaccine to prevent disease (Malakoff 2016). This has previously occurred in the terrestrial environment mainly to prevent the spreading of rabies in racoons and fox, but never in free-living marine mammals. The lack of genetic diversity, low population, and isolation the Hawaiian monk seal experiences makes it extremely susceptible to infection. But, these factors also make the seals a prime candidate for this vaccine. Scientists are wary of the spread of viruses in the Morbillivirus family. This genus of viruses has killed tens of thousands of seals and porpoises in the Atlantic Ocean. These viruses are easily spread and are possibly carried to the Hawaiian Islands by whales, stray seals and dogs. An outbreak among the monk seals could prove deadly and cause devastating decreases in an already struggling population. The vaccine is targeting the phocine distemper virus (PDV), which needs two shots, a first dose and then a booster 4-6 weeks later. The seals habits of “hauling out”, lying on the beach and rocks, their numbered tags, small population size and unique markings help with the recapture needed to complete the vaccine. Before the vaccines were implemented, model simulations of different scenarios were run to see if preventative vaccination would be worthwhile. Baker, Harting et al. (2017) along with Malakoff (2016) determined that preventative vaccination is the most effective way of protecting these seals from an Morbillivirus outbreak. In 2016, scientists started to vaccinate individuals at the Oahu “haul out”, as this is a midpoint between the subpopulations. 60% of the overall population would need to be vaccinated in order to prevent a local outbreak of PDV. Malakoff (2016) and Baker, Harting et al. (2017) provide some limitations to the vaccines. For future seals to be immune the vaccine will need to be continued and new pups will need to be vaccinated. These vaccines are not always available and are limited in quantity. To get to the seals, scientists must walk through tide pools and over lava rock which can be dangerous especially when dealing with wild animals. The vaccine takes over a month to provide protection which leaves the seals vulnerable. Also, the vaccines currently being used are for a different strain of PDV so this effort could be futile. Either way, this is a milestone for conservation and could be the protection the Hawaiian monk seals need to build a successful future.

Works Cited

Baker, J. D., A. L. Harting, M. M. Barbieri, S. J. Robinson, F. M. D. Gulland and C. L. Littnan (2017). “Modeling a Morbillivirus Outbreak in Hawaiian Monk Seals (Neomonachus Schauinslandi) to Aid in the Design of Mitigation Programs.” J Wildl Dis 53(4): 736-748.
Baker, J. D. and P. M. Thompson (2007). “Temporal and spatial variation in age-specific survival rates of a long-lived mammal, the Hawaiian monk seal.” Proc Biol Sci 274(1608): 407-415.
Malakoff, D. (2016). “CONSERVATION BIOLOGY. A race to vaccinate rare seals.” Science 352(6291): 1265.
Norris, T. A., C. L. Littnan, F. M. D. Gulland, J. D. Baker and J. T. Harvey (2017). “An integrated approach for assessing translocation as an effective conservation tool for Hawaiian monk seals.” Endangered Species Research 32: 103-115.
Schultz, J. K., J. D. Baker, R. J. Toonen, A. L. Harting and B. W. Bowen (2011). “Range-wide genetic connectivity of the Hawaiian monk seal and implications for translocation.” Conserv Biol 25(1): 124-132.

Sea-ice loss boosts visual search: fish foraging and changing pelagic interactions in polar oceans

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By Nicole Suren, SRC Intern

Light availability is one of the most important factors in the success of visual foraging. It can be controlled by many variables such as turbidity or weather, but in polar ecosystems ice cover and seasonality are the primary controls for light availability. Climate change has had and will continue to have a huge effect on polar ecosystems through temperature and weather changes, but one of the most notable side effects examined in this study is how increased light availability caused by receding ice and reduced snow cover will affect the success of polar visual foragers. The study modeled the success of planktivorous, visually foraging fish, with the underlying principle of the model being that increased ambient light will increase visual range, thereby making prey detectable at a larger distance and increasing foraging efficiency. The results showed that declines of polar sea ice would boost the visual search of planktivorous fish, but only seasonally. While light availability related to ice cover can be variable due to climate change, the long dark periods caused by polar seasonality are factors independent of climate, and therefore will still place limits on visual foraging during those seasons.

Figure 1

(a) The blue line shows how sea ice extent has decreased over the past decades, and below is a diagram demonstrating that prey will become more likely to be visually detected as the thickness of sea ice decreases. (b) A variety of factors influence prey detection, including the nature and angle of incoming light. Predator, prey, and visual range are not drawn to scale. (Langbehn & Varpe, 2017)

The models predict that several things will change due to light availability caused by loss of ice cover. First, primary productivity may increase, depending on nutrient availability. Second, seasonal feeding migrations into the poles are expected due to the removal of the limiting factor of lack of light for visual foragers. This prediction has already been verified by real-world data; increased feeding forays by Atlantic Salmon, Atlantic Mackerel, and Atlantic Herring have been recorded, and these coincide with decreasing ice cover over the past 35 years. More generally, mobile, fast-swimming predators are predicted to take advantage of these foraging opportunities the most. However, increased light availability can also increase the likelihood of planktivorous predators being spotted and predated upon by larger visual predators in a higher trophic level. This means that not only will the ideal user of these seasonal foraging grounds be mobile and fast-swimming, but they will either be apex predators or schooling fish, which can use the technique of schooling to forage in relative safety despite being visible.

Figure 2

The extent of sea ice is averaged from 2010-2015 in (a) and (b), and (c) and (d) show how visual range correlates with these averages. Data from the Bering Sea and the Barents Sea are shown. (Langbehn & Varpe, 2017)

No matter how efficiently visual foragers learn to take advantage of increased light availability at the poles during the summer months, the darkness of winter will still be a significant limiting factor in regards to permanent habitat expansion. Polar winters will always be long and dark, even if climate change alters the ice cover in that time. This means that the permanent inhabitants of the poles will likely remain the only permanent inhabitants due to their specialized adaptations for living in darkness, while trophic interactions are likely to change during the summer.

Work Cited

Langbehn, T. J., & Varpe, Ø. (2017). Sea-ice loss boosts visual search: Fish foraging and changing pelagic interactions in polar oceans. Global Change Biology, (November 2016). https://doi.org/10.1111/gcb.13797

Polar Bears are Vulnerable to Loss of Sea Ice

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By Rachael Ragen

Figure 1

Polar Bear, https://sealevel.nasa.gov/ system/news_items/main_images/ 74_polarbear768.jpeg

Polar bears are currently facing a major problem: declining sea ice. As greenhouse gases continue to increase due to anthropogenic factors causing temperatures to rise and ice to melt. Since polar bears rely on sea ice as they search for prey, the decline in sea ice makes hunting much more difficult. The current population of polar bears is estimated to be 26,000 with 19 subpopulations in 4 ecoregions (Figure 2). It is very difficult to properly assess each subpopulation of polar bears as they live in extreme environments. Therefore, no global assessment has been done and the status of some subpopulations is unknown. The study by Regehr et al. aimed to look at the effect of sea ice decline on polar bears by determining the generation length, forming a standardized sea ice metric, and then using statistical models and computer simulations.

Figure 2

Map of Ecoregions, Regehr et al.

In order to determine the generation length, the authors looked at the age of female polar bears with a cub and found the average to be 11.5 to 13.6 years. Live capture data was used to determine these numbers. The upper level is used to account for variations in generation length.

A sea ice metric was determined using satellite data from 1979 to 2014. This data was used to establish the carrying capacity, which is the maximum amount of organisms the habitat can support, for the polar bears. Then the value found for K (carrying capacity) was used in linear models. This analysis generated predicted future values of ice as well, as the effect these values had on subpopulations. The ice decline was shown to affect all subpopulations.

The statistical models and computer simulations looked at the relationship between polar bear populations and sea ice over three generations using three different methods. First they assumed that changes in sea ice are directly proportional to changes in subpopulation abundance. This method was useful for populations with limited data. Second they looked at a linear relationship between ice and subpopulation abundance for subpopulations, although data was only available for seven of the nineteen. There was not shown to be a significant change due to variations in the status subpopulations as well as uncertainty in estimates of abundance. Lastly they again looked at a linear relationship between ice and population but for each of the four ecoregions. Some ecoregions showed a significant change, whereas others did not, showing that dynamics and biological productivity varies between subpopulations.

Figure 3

Table of data found, Regehr et al.

This study looked at the IUCN Red List’s guidelines for risk tolerance. The culmination of these studies showed that the first generation’s mean global population size was to decrease by 30%, the second by 4%, and the third by 43% (Table 1). Since there was shown to be a high risk of the population decreasing by 30% and a low chance of the population decreasing by 50% (Table 1), polar bears are classified as vulnerable.

The need for MPAs in the Antarctic

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By Haley Kilgour, SRC Intern

With global climate change in effect the Arctic ice sheet has been losing area and has gone from 7.5 million km^2 in 1979 to 4 million km^2 in 2016 (Figure 1). The loss of ice coverage is detrimental to many species, but on the other hand opens up areas to new fishing grounds, oil and gas deposits, deep sea minerals, and shorter shipping routes that were previously inaccessible. While economically it is beneficial to exploit these now accessible resources, it is also necessary to designate Marine Protected Areas (MPAs) to preserve habitat and biodiversity.

Figure 1

Year round see ice cover for the periods of 1979-1984 and 2012-2016.

Geomorphic features such as seamounts, submarine canyons, hydrothermal vents, submarine plateaus, ridges, and escarpments serve as a proxy for benthic communities and ecological processes as they are often areas of high biodiversity and important to processes such as upwelling. Harris et al looked at the distribution of geomorphic features on the sea floor to assess their current level of protection within MPAs. They also aimed to see if these features were occurring within or outside of MPAs and identify ones that were once inaccessible due to year round sea ice.

To determine their area of study, Harris et al used the average minimum sea ice coverage from 1979-1983. They looked at the years 1979-1983 and 2012-2016 (the earliest and latest time periods) to see how much of the geomorphic features are now exposed. Twenty-nine categories of features were mapped using Shuttle Radar Topography Mapping (Shuttle Radar Topography) and MPA boundaries were taken from the IUCN and UNEP-WCMC database. The program ArcGIS was then used to compute areas.

On average, 31% of all previously year round covered features in the Arctic are now in open water in September. In 1979-1983, only 2.33% of areas below year round sea ice were in MPAs, and these were mostly areas on coastal and shelf habitats (Figure 2). This lack of diversity in features that are protected means there is high potential for them to be exploited now that year round ice no longer prevents access.

Figure 2

MPAs within the Arctic in relation to September sea ice cover in the periods 1979-1983 and 2012-2016.

As it stands, only 2.3% of the areas used in this study are in MPAs. While this seems to pose a problem, Canada, Denmark, Russia, Norway, and the USA have signed a “Declaration concerning the regulation of unregulated high seas fishing in the central Arctic Ocean” and a moratorium. Thereby, the areas beyond national jurisdiction have a degree of protection from fishing pressure at the current time.

Current MPAs mostly cover coastlines and inner shelf regions. Abyssal plains are not covered at all and there negligible protection for slope habitats. While the current MPAs do provide a small effect, they are not representative in the standard MPA design.

There are many geomorphic features that have been left exposed and all are fragile ecosystems. Basins collect sediment and anthropogenic contaminants, making them particularly susceptible to pollution from runoff and chemicals. Submarine canyons are considered biodiversity hot spots and prime fishing grounds, making them vulnerable to degradation. Only .2% of canyons are within existing MPAs and retreating sea ice now exposes 37% of their area. Submarine canyons face particular danger because they are associated with oil and gas deposits. Plateaus are mostly unexplored worldwide and thus need further examination and protection.

These underwater geomorphic regions are high in biodiversity but are finding themselves in peril with retreating sea ice. Many of these areas are likely under rapid ecological transition as the Arctic responds to global climate change. These ecosystems are highly unexplored and sensitive. They could be lucrative economically, but are also most likely highly important for conservation. MPAs will play a major role in protecting these areas.

Does marine debris affect tourist perception and tourism revenue?

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By Casey Dresbach, SRC Intern

The top worldwide providers of ecosystem services of both leisure and recreation include coastal areas such as beaches and estuaries (Millennium Ecosystem Assessment, 2005). These natural environments are home to hundreds of thousands of marine organisms, all of which require clean domains to flourish, thrive, and grow in. Unfortunately, human pollution has made its way into these areas, as depicted in Figure 1. “Marine debris” can be defined as any solid, persistent, human-created waste that has been deliberately or accidentally introduced into a waterway or ocean from shorelines to the ocean floor (Oregon Coast STEM Hub, 2017). Not only does this breed of debris directly affect marine species ocean-wide, but current research is also showing that it is taking a toll on both tourism and tourists’ destination choices worldwide.

Figure 1

Dr. Sylvia Earle engaging with a Laysan albatross nesting among marine debris. (USFWS – Pacific Region, 2012)

Marine debris is complex in its nature and jeopardizes other coastal entities. The debris has a dual effect on both the marine life as well income generated from local tourism. The interaction between marine debris and tourism is complex because items may form in regions other than the places where the litter is stranded and where tourism occurs (Krelling, Williams, & Turra, 2017). Individuals visiting beaches and coastal regions are more likely so seek alternate destinations if their overall experience is not remarkably enjoyable, and a substantial amount of scattered litter may play into that alternative choice of destination.

The coast of Paraná state in southern Brazil is one of the most frequented tourist destinations in this region (Krelling, Williams, & Turra, 2017). Many tourists, such as second-home owners and users (SHOU) and non-recurrent vacationers, frequent this Brazilian coast. A single SHOU is an individual or group of individuals who have an additional property, or vacation home elsewhere. And a non-recurrent tourist is an individual who has no territorial tie to a destination – is interested in vacation without having loyalty of a piece of land. In a recent study by researchers Allan Krelling, Allan Williams and Alexandra Turra, both the perceptions and reactions of these two distinct groups of beach users were compared. More than 70% of the visitors are SHOU. In fact, some of Paraná’s cities are dependent on property taxes from these second homeowners as well as the expenditures spent by the non-recurrent tourists on services such as food, activities, and other conveniences. Collectively, the two user groups and their tourism revenue drive the economy in the coastal area.

Figure 2

(a) Depicts the entire coastal region of Paraná State in southern Brazil. (Top right) Pontal Do Sul, a highly frequented estuarine beach in the coastal region of southern Brazil. (Bottom right) lpanema, a highly frequented open ocean beach in the coastal region of southern Brazil (Krelling, Williams, & Turra, 2017).)

The study compared both the perceptions and reactions of the two user groups. SHOU and non-recurrent tourists were administered a questionnaire to determine socioeconomic characteristics at two Brazilian sub-tropical beaches: Pontal do Sul and Ipanema, exhibited in Figure 2. Pontal do Sul is an estuarine beach and Ipanema is an open-ocean beach, which is more frequented by non-recurrent tourists. The ultimate goal of the questionnaire was to characterize these beach users’ socioeconomic characteristics such as yearly income, level of education, daily per person expenditure, frequency of trips and period of permanence (Krelling, Williams, & Turra, 2017). The survey also examined perceptions and reactions, especially those regarding the potential negative economic impacts of marine debris. Pontal do Sul and Ipanema were selectively chosen because of their varying geographical characteristics, ultimately adding more variability to the study set.

The general findings showed that SHOU might have a different reaction towards the marine debris than the average tourist. This can be linked to their loyalty to the destination, specifically tied to the property they have there. Results did show, however, that if debris were to reach a significant amount (>15 items/m2), more than 85% of beachgoers would look elsewhere when searching for a coastal region to vacation (Krelling, Williams, & Turra, 2017). If this were the case the stranded litter would threaten the Brazilian economy by reducing local tourism income by 39.1%, (Krelling, Williams, & Turra, 2017) which would present losses up to $8.5 million a year.

In order to improve beach users’ experience, moving forward, an issue like marine debris should be prioritized. Marine debris can be a stressor that impacts coastal tourism worldwide. An evaluation of economic impacts caused by litter presence is a unique approach to analyzing how to minimize the threat litter may pose to tourism revenue. Some factors that may influence a visitor’s beach choice may include beach length, scenery, water quality, amenities (restaurants, shops, etc.), and quantity of litter. The additive effect of these factors determines the overall impression the trip will leave on the visitor. Stranded beach litter is considered to be one of the five most important aspects regarding beach quality in Europe, USA, Mexico, and the Caribbean (Krelling, Williams, & Turra, 2017). More research should be done in order for authorities to decide how to best go about balancing investments to remove marine litter and minimize the potential reduction of tourism revenue. Through integrated planning, the sources of litter can be determined and preventive strategies can be put into play. This would help to avoid a reduction in environmental quality and income generated from tourism.

Works Cited

Krelling, A. P., Williams, A. T., & Turra, A. (2017, August 15). Differences in perception and reaction of tourist groups to beach marine debris that can influence a loss of tourism revenue in coastal areas. (H. Smith, Ed.) Marine Policy.

Millennium Ecosystem Assessment. (2005). Ecosystems and Human Well-being: Synthesis. Washington, DC: Island Press.

Oregon Coast STEM Hub. (2017). Marine Debris – Composition and Abundance. (L. C. Schools, O. C. Newport, N. M. Program, & S. G. (Oregon), Producers) Retrieved from Conserve Wildlife New Jersey:
http://oregoncoaststem.oregonstate.edu/marine-debris-steamss/md-grades-4-5/composition-and-abundance

USFWS – Pacific Region. (2012, January 11). Dr. Sylvia Earle talks to an albatross nesting among marine debris. (A. Collins, Producer) Retrieved from Wikimedia Commons: https://commons.wikimedia.org/wiki/ File:Dr._Sylvia_Earle_talks_to_an_albatross_nesting_among_marine_debris.jpg

Investigating Atlantic Salmon Dive Behavior in the Norwegian and Barents Seas

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By Grant Voirol, SRC Intern

Atlantic salmon, Salmo salar, are both an economically and ecologically important organism. An anadromous fish, Atlantic salmon spend most of their lives at sea before swimming into freshwater rivers to spawn. While at sea, Atlantic salmon periodically migrate to depths deeper than 10 meters. One proposed model of their diving behavior is that the salmon dive to deeper colder waters to feed before returning to shallower warmer water to digest. In this way, they can maximize their energy conservation (Reddin et al 2004). However, in colder waters of the most northern Atlantic, temperatures of shallower water are not significantly warmer than the depths that salmon can reach. So what factors govern Atlantic salmon diving behavior in these colder waters?

Picture 1

Atlantic salmon are both popular sport fish throughout the Atlantic as well as important predators and prey. Photo: Hans-Petter Fjeld (CC-BY-SA).

A recent study sought to find out. To do so, researchers studied post-spawning Atlantic salmon in the Norwegian and Barents Seas over season and daily timescales. Three populations from the three rivers Orkla, Alta, and Neiden, were caught and tagged using pop-up satellite archival tags (PSATs) and data storage tags (DSTs). PSATs measure temperature and depth and are attached externally to the salmon. They release themselves from the fish if a predetermined period of days goes by, the fish dives to a depth that will harm the tag (1200 meters), or the tag registers a constant depth, usually meaning the fish has died. Once they release themselves, the tags send a signal to satellites where the data collected as well as its position can be downloaded. DSTs are inserted internally in the salmon and measure temperature and depth at a much higher resolution. However, since the tags are inserted into the salmon, these salmon must be recaptured in order to retrieve the data. Recapture was dependent on fishers who would receive a reward for returning the tags to the researchers.

The findings show that the three groups of salmon displayed similar patterns of dive behavior during the sampled period. On the seasonal time scale, salmon went to deeper depths during winter and spring following the depth of the mixed layer (Figure 1). On daily timescales, the salmon occupied greater depths during daylight hours and returned to nearer to the surface during nighttime hours (Hedger et al. 2017).

Figure 1

Median dive depth per month. Solid line shows depth of the mixed layer. Increases in dive depth occur during the months of November to May. (Hedger et al. 2017)

A better understanding of the distribution and behavior of different populations of Atlantic salmon is important in order to know if different management practices need to be employed in different areas. Furthermore, this information gives us a better picture of the role that Atlantic salmon play in the Northeast Atlantic as both a predator and prey species.

Works Cited

Hedger RD, Rikardsen AH, Strøm JF, Righton DA, Thorstad EB, Næsje TF (2017) Diving behaviour of Atlantic salmon at sea: effects of light regimes and temperature stratification. Mar Ecol Prog Ser 574:127-140.

Reddin DG, Friedland KD, Downton P, Dempson JB, Mullins CC (2004) Thermal habitat experienced by Atlantic salmon (Salmo salar L.) kelts in coastal Newfoundland waters. Fish Oceanogr 13: 24−35.

A comparative analysis of the behavioral response to fishing boats in two albatross species

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By Andriana Fragola, SRC Intern

This paper examines the behavior of the Wandering Albatross (WA) and Black-Browed Albatross (BBA), and how they are affected by the toothfish longline fleet in Kerguelen and Crozet (Collet et al. 2017). To do this, lightweight GPS loggers were attached to adult albatrosses of both species to track their movements. To track the fishing boats, VMS data was provided to the researchers which allowed them to log their movements (Collet et al. 2017).

Calculations were done to establish the maximal distance that birds were seen flying towards the fishing boats. To isolate the different behaviors of the albatross the researchers established “encounter” as well as “attendance” behaviors to assess the responses of the birds to these fishing vessels (Collet et al. 2017). Encounters were defined as more by chance when the birds were in flight, while attendance behavior was defined as sitting in the water within a close range of the vessels (Collet et al. 2017).

Figure 1

[Source: Collet et al. 2017]

Results demonstrated that the Black-Browed Albatross (BBA) did not come into contact with fishing vessels as often as the Wandering Albatross (WA) (Collet et al. 2017). BBA also seemed to forage in areas that were a greater distance from the fishing vessels than WA (Collet et al. 2017). When the vessels were absent, BBA were not seen foraging in the regions where the vessels typically operate, while WA were (Collet et al. 2017).

Although WA are the larger and more dominant species, they were not observed pursuing the fishing vessels as much as the researchers had expected (Collet et al. 2017). BBA had an 80% chance of being attracted to fishing vessels, while WA had a lesser 60% chance of being attracted to the boats (Collet et al. 2017).

There were apparent differences between these two species and their utilization of fishing fleets as a means for foraging (Collet et al. 2017). This paper suggests that the energetic needs of each species can be an indicator of the risks associated with foraging from anthropogenic sources (Collet et al. 2017).

Figure 2

[Source: Collet et al. 2017]

It is vital to understand how species are becoming reliant on anthropogenic sources for food because this can affect their nutritional health. The quality of the fish that albatross are getting from these fishing vessels may not have the nutritional value of the fish they typically hunt. Further, if generations of these animals become dependent on these unnatural food sources, this can lead to issues – if the availability of that source becomes compromised, and birds are reliant to the extent that they do not have the skill to forage on their own.

Work Cited

Collet, J., Patrick, S. C., & Weimerskirch, H. (2017). A comparative analysis of the behavioral response to fishing boats in two albatross species. Behavioral Ecology, 28(5), 1337-1347.