Ocean Plastics

By: Nick Martinez, SRC Intern

The world’s oceans face a variety of challenges ranging from rising sea levels and sea surface temperatures, to overfishing and excessive amounts of anthropogenic debris being tossed into the oceans. Many studies have focused on the large scale effects of each of these dire issues, yet few have ventured into the realm of marine plastics and how these objects actually aid in the dispersal and recruitment of various species throughout the oceans of the world. Since the earliest known recording of anthropogenic waste in the world’s oceans back in the 1970’s (Goldstein et al. 2014), scientists have begun paying particular attention to the way many sessile species have proven to be a key foundation species in the recruitment and dispersal of various organisms throughout the world. Due to the anatomy of these sessile species, scientists have found a variety of microecosystems thriving on the surface of these plastics. Barnacles and other sessile species turn the smooth, unprotected surfaces of the plastics into a more structured surface where rafting organisms can hide and seek shelter from the otherwise harsh pelagic conditions. Because these ocean plastics have been virtually transformed by sessile organisms, these plastics and other anthropogenic debris augment a natural floating substrate in the open ocean, allowing “islands” of substrate-associated organisms to persist in an otherwise unsuitable habitat (2014). In other words, these sessile species have been able to successfully recruit and colonize these ‘floating islands,’ granting them the unique opportunity to create an environment where other organisms can survive and travel vast distances across the Pacific and Atlantic oceans (Fig 1). While this is certainly a unique way of nature overcoming one of our many detrimental anthropogenic effects, there is in fact a small trojan horse that this feat of nature carries throughout the world’s oceans. With the ability to travel vast distances across the ocean, scientists have begun uncovering the major issue of invasive species dispersal and global disease spread between the ‘floating islands’ and foreign ecosystems. To understand exactly how this is possible, a closer look into the plastics and their superiority over biotic debris must be taken into account.

Figure 1. In boxes a, b and c we can see a collection of barnacles that have colonized the various plastic substrates. In box d, we see a small trigger fish that has made the floating debris its home. In boxes e and f we see a close up view of the lethal folliculinid ciliates that cause skeletal eroding band disease in corals (Gill and Pfaller 2016).

For hundreds of millions of years, organisms have had limited travel on floating marine algae, plant trunks, pods, or other biotic floating parts (Barnes et al. 2004). In fact, scientists were previously aware of marine organism dispersal to other parts of the world via debris transportation. However, the key difference between the biotic and anthropogenic debris is that anthropogenic debris lasts significantly longer than biotic debris. The ability for plastics to resist degradation, made it highly persistent to haline environments and environments exposed to harsh UV light for long periods of time. For this reason, ocean plastics have drastically increased the dispersal for many marine organisms throughout the world (Carlton 1987). The plastics alone, however, would be nothing without the various sessile taxa that have transformed the smooth substrate of the plastics into a more rugged surface suitable for protection from the harsh pelagic conditions. With protection from the harsh conditions, organisms are more likely to successfully recruit to that environment and survive long periods of time. Thus, with a significantly longer lifespan and the ability for organisms to successfully recruit onto the transformed surfaces of the debris, ocean plastics have been able to transport organisms from as far south as the southernmost tip of South America to the northernmost reaches of Greenland (Fig. 2). While this is certainly a unique feat of nature, it poses a lot of issues regarding species invasion and the forced eradication of native species over time.

 

Figure 2. This figure shows a collection of plastic debris sampled from the southern to the northern hemispheres of the Atlantic oceans. The dark circles represent floating debris while the open circles represent debris sampled on the shores of small islands. Each sample produced an abundance of various organisms all thriving off of the ecosystem created by barnacles (Gill and Pfaller 2016).

Figure. 3. In this figure we see a collection of histogram charts displaying the abundance various taxa found on or around floating debris (Goldstein et al. 2014).

In a study conducted on the effects of Lepas barnacles (a proven foundation species for ocean plastics) by Gil et al. 2016, shows that these organisms were able to recruit a higher abundance of mobile taxa not previously observed on any floating debris. In fact, Gil goes on to state that the structural habitat provided by the Lepas barnacles could facilitate settlement of immigrating organisms e.g., adults or larvae originating from faraway coastlines or other rafts (Fig. 3). For this reason, Gil states that the barnacles’ ability to recruit a diverse array of species can prove detrimental to coastal ecosystems around the world. With the ability to successfully recruit and disperse organisms over long periods of time, there’s no way of stopping the invasion of foreign species to coastlines around the world. In addition to the dispersal of invasive species to foreign coastlines, scientists have also found an abundance of a folliculinid ciliate native to the South Pacific and Indian oceans that has managed to make its way to the Caribbean and the Hawaiian islands via plastic debris (Goldstein et al. 2014). This disease is a lethal pathogen that triggers skeletal eroding band disease in corals and while it was predominantly a disease with a fixed environmental range, ocean plastics have allowed the pathogen to cross borders and affect foreign reef systems. With the discovery of ocean plastics as being a viable source for transportation and dispersal, scientists have come to realize the detrimental effects of plastic debris beyond just polluting the ocean’s waters. Though scientists have all called for further studies regarding this topic, there is no doubt that the active limiting of plastic debris being thrown into the ocean needs to be taken more seriously.

Work Cited:

Barnes, D. & Milner, P. Drifting plastic and its consequences for sessile organism dispersal in the Atlantic Ocean. Mar. Biol. 146, 815–825 (2005).

Carlton JT. Patterns of transoceanic marine biological invasions in the Pacific Ocean. Bull Mar Sci  41:452–465 (1987).

Gil, M.A., & Pfaller, J.B. Oceanic barnacles act as foundation species on plastic debris: implications for marine dispersal. Scientific reports (2016).

Goldstein, M., Carson, H. & Eriksen, M. Relationship of diversity and habitat area in North Pacific plastic-associated rafting communities. Mar. Biol. 1–13, doi: 10.1007/s00227-014-2432-8 (2014).

 

Marine Protected Area (MPA) Effectiveness

By: Olivia Wigon, SRC Intern

Marine Protected Areas (MPAs) encompass any and every type of area in the oceans, seas, lakes or estuaries. MPAs have some type of restriction on human behavior and activity in an area with the intention to conserve natural resources in that area. MPAs not only protect animals but the economy through tourism and fishing. Divers and other ocean lovers will travel to see marine protected areas because of the large animals and the amount of life in them which stimulates the local economy. MPAs also help fishermen because the fish have time to grow and reproduce providing fishermen with sustainable amount of large fish to catch when the fish leave the MPA. While there has been an increase in MPAs, there are still challenges in determining the social and economic benefits of them (Edgar et al. 2014). Graham J. Edgar and his team looked at 87 MPAs located all around the world and found that they are most successful when there are 5 key features. The 5 features are well enforced, no take, isolated by deep water or sand, are older than 10 years, and are larger than 100 square kilometers. An effective MPA has twice as many large fish, five times more large fish biomass, and fourteen times more shark biomass than in unprotected areas (Edgar et al. 2014). Unfortunately, Graham J. Edgar and his team found that only 41% of MPAs studied had 3 or more of these key features. It is important to note that each MPA is different and is designed with different circumstances in mind. For example, an MPA may be designed for a specific species in mind, or for a specific time of year.

Globally shark populations are struggling due to over fishing, climate change, and shark finning. Additionally, shark populations take years to recover because they are k-selected species which means they have long life spans, few offspring and late sexual maturity. Humans are also k-selected animals. This has resulting in urgent conservation effort, including establishing marine protected areas in various shark habitats. Many species of sharks are pelagic which means that they travel great distances in the open ocean. Conservation for pelagic species is difficult because they are constantly moving so they will be protected in one area but as soon as they swim out of the MPA it is at risk again. In order to understand how MPAs protect sharks Danielle M. Knip and her team used acoustic tags and receivers around the Great Barrier Reef Marine Park in Australia. Both juvenile pigeye and adult spot-tail sharks were given acoustic tags. The juvenile pigeye sharks were found to spend more time in the MPAs during the summer and the adult spot-tails spent more time there in the winter (Knip et al. 2012). The MPAs in this study were shown to be effective because they protect multiple species, at various life stages, during various times of the year. Knips team also looked at how often sharks were leaving the marine protected area and where they were exiting and entering the MPAs. While the MPAs studied were not specifically designed for shark conservation they are aiding in the efforts to protect shark populations.

Conrad W. Speed and his team looked at how long it takes a shark population to rebound after exploitation and how the establishment of MPAs helps the recovery process (Speed et al. 2018). The team used baited remote underwater video stations (BRUVS) which are essentially a camera attached to a bait box which allows researchers to see what animals live in the area and how many of them there are. The team collected data both before and after several years of strict MPA enforcement. The MPAs the team looked at were well-managed and were no-take zones which means that nothing could be caught or removed from that area. Speed and the team saw a significant increase in apex species, and reef shark populations. Similar results were found amongst all the MPAs that were studied. Overall, the data shows that when marine protected areas are established and enforced for a significant amount they are effective in regards to an increase in fish biomass and an increase in shark populations. As the environmental movement grows there is becoming a greater demand for the creation of new marine protected areas and better management of those already established.

Work Cited:

Edgar, Graham J., et al. (2014) “Global Conservation Outcomes Depend on Marine Protected Areas with Five Key Features.” Nature, vol. 506, no. 7487, pp. 216–220., doi:10.1038/nature13022.

Knip, Danielle M., et al. (2012) “Evaluating Marine Protected Areas for the Conservation of Tropical Coastal Sharks.” Biological Conservation, vol. 148, no. 1, pp. 200–209., doi:10.1016/j.biocon.2012.01.008.

Speed, Conrad W., et al. (2018) “Evidence for Rapid Recovery of Shark Populations within a Coral Reef Marine Protected Area.” Biological Conservation, vol. 220, pp. 308–319., doi:10.1016/j.biocon.2018.01.010.

Predicting Fisheries Collapse

By: Chris Schenker, SRC Intern

Figure 1: Some fisheries, such as skipjack tuna (left) remain profitable. Shown to the right, blue bars indicate fisheries that remain close to target biomass, while red bars indicate fisheries that generate profit. Predictions for 2050 are shown based on business as usual (BAU), maximum sustainable yield through catch limits (MSY), and maximum profit through rights-based fisheries management (RBFM). (Worm et al., 2009)

Hundreds of millions of people around the world depend on wild harvests from the ocean as both a livelihood and source of protein (Srinivasan et al., 2010). Ensuring the long term sustainability of fisheries is therefore a matter of utmost importance for global resource security. However, according to a 2016 paper in PNAS, global fish stocks are on average poor and declining (Costello et al., 2016). Of the 4,714 fish stocks analyzed by Costello et al. in 2012, 68% were below the biomass target that supports maximum sustainable yield (referred to as BMSY). Considering a level of 63% of assessed stocks measuring below BMSY  in 2006 (Worm et al., 2009), there has been a clear decrease in fisheries health worldwide. Furthermore, the finding that only 35% of stocks in decline are being fished at a rate that puts them back on target to achieve BMSY indicates that this trend is set to worsen (Costello et al., 2016).

In order to avert a collapse in the world’s fisheries, it is therefore important to understand which species are at greater risk than others. Terrestrial surveys suggest that large bodied, high trophic level species are the most susceptible to population decline due to human pressure. While this was long assumed to also be the case for marine species, recent evidence has suggested otherwise. Pinsky et al. analyzed two independent fisheries databases and global landings from 1950 to 2006 as reported by the UN Food and Agriculture Organization (FAO) in order to test this hypothesis (Pinsky et al., 2011).

Neither the assessment data nor the landings data supported the idea that fisheries collapse across only a small range of life history traits. In the analysis of the assessment data, 12% of stocks of high trophic level species experienced collapse, but 25% had collapsed among low trophic level species. When comparing by size, 16% of large species collapsed versus 29% of small species. While these figures suggest a higher likelihood of collapse in smaller, low trophic level species, linear regression models did not support any significant relationship between stock collapse and trophic level (P = 0.15), weight (P = 0.26), longevity (P = 0.10), age of maturity (P = 0.92), fecundity (P = 0.77), or investment in offspring (P = 0.99). The landings data supported the conclusion that small, low trophic level species are just as vulnerable as large, top predators, and individual life history traits alone did not explain significant variation in stock collapse (Pinksy et al., 2011).

Figure 2: Global variation by large marine ecosystem in (a) proportion of stocks that have ever collapsed, and (b) climate variability from season to season. (Pinsky et al., 2015)

In a 2015 paper, Pinsky et al. created boosted regression trees for 154 populations of fish worldwide in order to analyze the effects of harvesting, life history traits and climate variability on the risk of collapse. As expected, overfishing was the most important predictor of collapse. Chronic overfishing correlated to depletion, while acute overfishing correlated to collapse (Pinsky & Byler 2015). However, certain life history traits and climate variability were found to predispose populations for collapse.

Fast-growing species in variable climates appeared particularly sensitive to overfishing. Species with short generation times can rebound faster than longer generation species, but they can only tolerate smaller lags in harvest rate reductions. When coupled with productivity lows caused by climate variability, fast growing species become difficult to manage and require proactive oversight. There are limitations to the datasets used to arrive at this conclusion, such as the low number of tropical climates assessed, but it is clear that more variability exists than can be explained by simple extinction models (Lande, 1993). More complex models incorporating multiple, interacting drivers of stock declines appear useful for better predicting future collapses.

Stock assessments are an important component of most management systems, but their prohibitive cost often means they can only be completed infrequently. It is therefore imperative to maximize the value of an assessment by deriving as much information about as many species as possible. In PNAS, Burgess et al. (Burgess et al. 2013) suggest a new system for predicting future population declines. The theory assumes that the species in any multispecies fishery are connected to each other by the shared threat of effort. This means that the fate of all species can be predicted if the fate of one species can be predicted.

Figure 3: Comparison of assessment histories and points of earliest identifiable threat based on T-score. (Burgess et al., 2013)

The logic behind this assumption is that in any fishery, most of the harvesting will be directed at key species, and this will drive future mortality from fishing for all species. Target species are usually monitored more consistently and have more extensive datasets of past and present stocks (Burgess et al., 2013). By using differences in life history traits between key and other species and projections of future mortality from fishing, the authors created a T-score or “eventual threat index” for any given species across all of the fisheries in which it is caught. A T-score < 1 means a species is not at risk, while greater than one means a weak stock is on track to become overfished. Once T increases to > 2, the species is at risk to become extinct due to incidental fishing pressure.

This new approach promises to boost the effectiveness of fisheries management worldwide. Eight populations of Pacific tuna and billfish were analyzed with this technique, four of which are severely depleted. Had this method been available then, the authors claim that the decline of these populations could have been predicted in the 1950’s (Burgess et al., 2013). Such early detection could have positive economic impact and save decades in recovery time. However, alternative solutions are still needed in less developed countries lacking sufficient assessment and regulation. If depleted fish populations in these countries are ever going to recover, new sources of income and nutrition must be found to supplement the role that fishing has traditionally filled. Saving global fisheries from collapse is possible, but it will require innovative new science, strict regulation, and engagement with less developed communities that rely on the sea for livelihood.

Works Cited:

Burgess MG, Polasky S, Tilman D (2013) Predicting overfishing and extinction threats in multispecies fisheries. Proc Natl Acad Sci USA110:15943–15948.

Costello C, et al. (2016) Global fishery prospects under contrasting management regimes. Proc Natl Acad Sci USA 113:5125–5129.

Lande R. 1993 Risks of population extinction from demographic and environmental stochasticity and random catastrophes. Am. Nat. 142, 911–927

Pinsky ML, Jensen O. P. , Ricard D., Palumbi S. R. 2011 Unexpected patterns of fisheries collapse in the world’s oceans. Proc. Natl. Acad. Sci. U.S.A. 108, 8317–8322. doi: 10.1073/pnas.1015313108; pmid: 21536889

Pinsky ML, Byler D. 2015. Fishing, fast growth and climate variability increase the risk of collapse. Proc. R. Soc. B 282:20151053

Srinivasan, U.T., Cheung, W.W.L., Watson, R. et al. J Bioecon (2010) 12: 183. doi: 10.1007/s10818-010-9090-9

Worm B, et al. (2009) Rebuilding global fisheries. Science 325(5940):578–585.

What are harmful algal blooms (HABs) and why do they affect so many marine organisms?

By: Brenna Bales, SRC Intern

One cannot live in the state of Florida and be unaware of the effects of a red tide. It’s lethal destruction spurs concern from conservationists, divers, and fishermen alike. What begins as plankton at the basis of the food web, supplying nutrients to shellfish and larvae, gets sent into overdrive and wreaks havoc on marine and brackish ecosystems (Halegraeff 1993). How can such small organisms be responsible for so much harm?

Natural biogeochemical cycles, such as nutrient upwelling and salinity cycles, are responsible for creating plankton blooms composed of dinoflagellates, diatoms, or cyanobacteria (Sellner et al. 2003). A lethal domino effect is created when their populations explode. When zooplankton respire, they require oxygen and nutrients. In a bloom situation, the large amount of plankton may use up so much oxygen in the water that there is hardly any left for other animals that need it such as fish, crustaceans, and shellfish. These animals can then suffocate and die underwater (Anderson 2009). There are many occurrences of natural plankton blooms that we can observe, but an increasing number are attributable to anthropogenic effects (Anderson et al. 2008, Sellner et al. 2003). Humans, by fertilizing golf courses, personal lawns, and sewage dumping, can release organic nutrients into waterways which supply these plankton with nourishment, exploding their numbers.

A red tide is only one example of what is termed a harmful algal bloom (HAB). Over 300 species of plankton can contribute to a red tide, but there are other HABs that can be fatal to humans and animals such as paralytic shellfish poisoning, diarrhetic shellfish poisoning, amnesic shellfish poisoning, and ciguatera (Halegraeff 1993). Ciguatera is the most serious, affecting more than 50,000 humans annually (Anderson 2012). The mechanism by which these cause harm to the marine environment is not by oxygen depletion, but rather toxin accumulation. More and more toxins are discovered every year as research continues, which includes classes such as brevetoxins, saxitoxins, and anatoxins (Halegraeff 1993). These toxins accumulate in plants or small crustaceans/shellfish, which fish will eat. Larger predatory animals such as dolphins or sharks will then consume the infected fish and become poisoned. This is also known as bioaccumulation and can occur with any harmful substance making its way up the food chain such as mercury. When the algal blooms occupy many square miles, these animals can die in mass numbers and wash up on shore or float to the surface in large aggregations (Figure 1).

Figure 1. A red tide event causes fish to wash up on a popular beach near Tampa Bay, Florida. (http://wusfnews.wusf.usf.edu/post/pinellas-cleaning-beaches-red-tide-arrives)

There are three mechanisms by which a marine animal may become detrimentally affected by a HAB. The first is by ingestion, as described above. The second is by inhalation. This mainly affects marine mammals that come to the surface to breath air (Alcock 2007). Toxins from HABs can become aerosolized when algae burst underwater and release these toxins into bubbles that float up to the surface and explode into the air (Pierce 1986). The proximity of these airborne molecules to the water makes it easy for the particles to become inhaled by animals breathing at the surface such as whales and dolphins, thus infecting their airways. The third mechanism is by touch. Brevetoxins have been shown to be able to absorb into skin cells, and when animals’ skin in the water comes into proximity with a HAB, they can become infected (Kemppainen et al. 1991). For marine mammals and humans, all three mechanisms can combine ensuring a deadly fate.

Here in Florida there a well-known, HAB-causing organism: the dinoflagellate Karenia brevis (Figure 2). It is the most significant HAB-causing organism in the Gulf of Mexico (Anderson et al. 2008). K. brevis is a brevetoxin, which produces neuro and muscular toxins (Kirkpatrick et al. 2004). When infected fish are consumed by humans, they can cause nausea, vomiting, paresthesia (burning/tickling sensations) in the mouth, lips, and tongue, dizziness, slurred speech, and partial paralysis (Watkins et al. 2008). A recent study has shown that K. brevis can even affect the economically-important scleractinian coral species in Florida, by upsetting protein expression, metabolism, and oxygen production (Reynolds 2018).

Figure 2. Dinoflagellate Karenia brevis. Also known as Gymnodinium breve (Davis 1948), Ptychodiscus brevis (Steidinger 1979) (Wikimedia Commons).

Florida is flanked by oceans on both coasts, creating water-based industries such as snorkeling/diving, fishing, and going to the beach. Many people live on waterways that are susceptible to HABs, rendering them vulnerable to airborne effects. Combined impacts on public health, commercial fishing, recreation and tourism, and management cost the state an average $450 million annually from 1987-1992 (Anderson et al. 2000). Prevention and mitigation are essential for alleviating some of these negative impacts, especially if more and more HABs are being observed globally each year (Anderson 2012). As human populations become increasingly coastal, we must work together on finding solutions to this growing problem for both the sake of our oceans, and for ourselves.

Works Cited:

Alcock, F., 2007. An assessment of Florida red tide: causes, consequences and management strategies. Marine Policy Institute, Mote Marine Laboratory, Sarasota, FL.

Anderson, D.M., Hoagland, P., Kaoru, Y. and White, A.W., 2000. Estimated annual economic impacts from harmful algal blooms (HABs) in the United States (No. WHOI-2000-11). NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION NORMAN OK NATIONAL SEVERE STORMS LAB.

Anderson, D.M., Burkholder, J.M., Cochlan, W.P., Glibert, P.M., Gobler, C.J., Heil, C.A., Kudela, R.M., Parsons, M.L., Rensel, J.J., Townsend, D.W. and Trainer, V.L., 2008. Harmful algal blooms and eutrophication: examining linkages from selected coastal regions of the United States. Harmful Algae8(1), pp.39-53.

Anderson, D.M., 2009. Approaches to monitoring, control and management of harmful algal blooms (HABs). Ocean & coastal management52(7), pp.342-347.

Anderson, D., 2014. HABs in a changing world: a perspective on harmful algal blooms, their impacts, and research and management in a dynamic era of climactic and environmental change. In Harmful algae 2012: proceedings of the 15th International Conference on Harmful Algae: October 29-November 2, 2012, CECO, Changwon, Gyeongnam, Korea/editors, Hak Gyoon Kim, Beatriz Reguera, Gustaaf M. Hallegraeff, Chang Kyu Lee, M. (Vol. 2012, p. 3). NIH Public Access.

Hallegraeff, G.M., 1993. A review of harmful algal blooms and their apparent global increase. Phycologia32(2), pp.79-99.

Kemppainen, B.W., Reifenrath, W.G., Stafford, R.G. and Mehta, M., 1991. Methods for in vitro skin absorption studies of a lipophilic toxin produced by red tide. Toxicology66(1), pp.1-17.

Kirkpatrick, B., Fleming, L.E., Squicciarini, D., Backer, L.C., Clark, R., Abraham, W., Benson, J., Cheng, Y.S., Johnson, D., Pierce, R. and Zaias, J., 2004. Literature review of Florida red tide: implications for human health effects. Harmful algae3(2), pp.99-115.

Pierce, R.H., 1986. Red tide (Ptychodiscus brevis) toxin aerosols: a review. Toxicon24(10), pp.955-965.

Reynolds, D.A., 2018. The effects of the red tide producing dinoflagellate, Karenia brevis, and associated brevetoxins on viability and sublethal stress responses in scleractinian coral: a potential regional stressor to coral reefs.

Sellner, K.G., Doucette, G.J. and Kirkpatrick, G.J., 2003. Harmful algal blooms: causes, impacts and detection. Journal of Industrial Microbiology and Biotechnology30(7), pp.383-406.

Watkins, S.M., Reich, A., Fleming, L.E. and Hammond, R., 2008. Neurotoxic shellfish poisoning. Marine drugs6(3), pp.431-455.

The Study of Humpback Whale Songs as Indicators of Migratory Routes

By: Meagan Ando, SRC Intern

The migration of the Humpback Whale is one of the longest and mightiest journeys taken by any marine animal in the world. On average, these baleen whales travel about 6,000 miles every year, making this one of the most awe-inspiring ocean crossings. But just where do these animals travel to and how do we know?

Scientists have already set out to identify these tracks. A well-known method is through the identification of a specific animal via photographical evidence of the underside of the tail fluke. Each tail has a distinct pattern that serves the whale in the same way that a fingerprint does to a human: personal identity (Figures 1 and 2). Because of this, scientists are able to take pictures of these markings and compare them to pictures from prior years to match-up certain animals and analyze where they have been traveling to or from. From this data, it was proven that animals “migrate from summer feeding grounds in temperate or polar waters to winter breeding and calving areas in the tropics” (Kellogg 1929). However, it was still unclear as to which routes were being taken by the animals between these beginning-and-end locations.

Figure 1: The close-up of the underside of a Humpback Whale tail located in Cape Bay, Newfoundland. This is a sign that the animal is diving (Nilfanion 2008).

Figure 2: Photographs of five different whale flukes that vary in markings. This helps with the identification process (NOAA 2017).

In an effort to locate these specific routes, scientists turned to acoustic detections of the famous Humpback Whale songs. Each song consists of a highly-patterned series of different sounds that last anywhere from 6-35 minutes in length (Winn 1978). Identification of each individual animal was also made extremely possible because “each individual adheres to its own song type” (Payne and Mcvay 1971). While it was known that males usually produce these songs near their breeding grounds, it was also thought that they “sing along migration routes and on higher-latitude feeding grounds” (Vu et al., 2012). This hypothesis was further supported by the fact that for many years, while it was believed that “humpback whale singing was confined to tropical waters, […] singing [was] also documented with some frequency on migratory routes” (Clapham & Mattila 1990; Norris et al. 1999; Charif et al. 2001).

To test the theory of using songs as indicators of the whales’ migration routes, researchers used methods in which they could detect the songs throughout various parts of the ocean in order to successfully pinpoint where the animals were. It was previously known that Humpbacks from all populations migrated from many areas to a common ground in the West Indies to breed (Katona and Beard 1990). So, researchers set out on a cruise across the Atlantic Ocean to the Georges Bank area near Cape Cod, MA, USA to take a 25-day period recording using various pop-up acoustic monitoring systems (Clark and Clapham 2004). A pop-up is an autonomous acoustic recording system that measures sound waves through the use of a hydrophone and acoustic transponder. During the Spring of 2000, six of these instruments were deployed in the Bank area (Figure 3).

Figure 3: The locations of all six pop-up deployments in the western Georges Bank area. Data was recorded from these instruments from May 14, 2000 to June 7, 2000 (Clark and Clapham 2004).

The recording frequency ranged from 20-800 Hz, giving it a greater ability to detect the lower frequency range that male Humpback Whales sing at. After 25 days, this data was synchronized into six-channel data files and analyzed for presence/absence of singing as well as an estimate of the total number of whales singing at any given time (Figure 4). The range at which the sound waves were coming in was also a good indicator of distance from the acoustic pop-ups, allowing for pinpointed location of the whale’s track.

Figure 4: The six-channel data files’ spectrogram. This data shows the presence of the same song at all six locations, allowing for the conclusion of the direction in which the whale was traveling (Clark and Clapham 2004).

Researchers found that singing was detected during each hour of the day, giving a greater sample size and therefore more accurate data to draw conclusions from pertaining to the whales’ tracking pattern. The farthest locations detected were calculated to be 14-29 km away from each pop-up. They were also able to match up specific songs with specific animals to confirm that the mating season was still in session. This contradicted what many scientists had already believed about this breeding range. They suspected that breeding did not occur in such high latitudes. However, they were now able to conclude that “breeding season should no longer be considered as strictly confined to lower-latitude regions” (Clark and Clapham 2004).

In reference to migratory patterns, this data shows that Humpback Whales do in fact travel through areas that scientists are yet to expect. While tail fluke identification is a strong method for classification and should continue to be a way in which to pinpoint specific animals to assess health and areas of necessary protection, “many result from opportunistic or ‘casual’ encounters with animals”, which can end up being quite unreliable (Buckland 1990). Acoustic readings of songs can serve in more a successful way in order to know where specifically each population travels.

With continued research using acoustic monitoring such as the type used in this study, more specific locations can be identified in hopes of further protecting these animals. This methodology can also be applied to other species of cetaceans, allowing for researchers to locate where in the oceans they are breeding and strictly protect the area to allow for higher reproduction and survival rates.

Work Cited:

Buckland, S. T. “Estimation of survival rates from sightings of individually identifiable whales.” Report of the International Whaling Commission (special issue 12) (1990): 149-153.

Charif, R., Clapham, P. J., Gagnon, W., Loveday, P. & Clark, C. W. “Acoustic detections of singing humpback whales in the waters of the British Isles.” Mar. Mammal Sci. (2001). 17, 751–768.

Clapham, P. J. & Mattila, D. K. “Humpback whale songs as indicators of migration routes.” Mar. Mammal Sci. (1990). 6, 155–160.

Clark, Christopher W., and Phillip J. Clapham. “Acoustic monitoring on a humpback whale (Megaptera novaeangliae) feeding ground shows continual singing into late Spring.” Proceedings of the Royal Society B: Biological Sciences 271.1543 (2004): 1051.

Katona, S. K. & Beard, J. A. “Population size, migrations and feeding aggregations of the humpback whale (Megaptera novaeangliae) in the western North Atlantic Ocean.” Rep. Int. Whal. Commiss. (1990). 12: 295–305.

Kellogg, R. “What is known of the migrations of some of the whalebone whales.” A. Rep. Smithson. Inst. 1928, (1929). pp. 467–494.

Nilfanion. “User:Nilfanion.” Category: Heidentor (Carnuntum) – Wikimedia Commons, Wikimedia Foundation, Inc., 28 July 2008.

NOAA. Hawaiian Island Humpback Whale National Marine Sanctuary. National Ocean Service, 31 July 2017.

Norris, T. F., McDonald, M. & Barlow, J. “Acoustic detections of singing humpback whales (Megaptera novaeangliae) in the eastern North Pacific during their northbound migration.” J. Acoust. Soc. Am. (1999). 106, 506–514.

Payne, Roger S., and Scott McVay. “Songs of humpback whales.” Science 173.3997 (1971): 585-597.

Vu, Elizabeth T., et al. “Humpback whale song occurs extensively on feeding grounds in the western North Atlantic Ocean.” Aquatic Biology 14.2 (2012): 175-183.

Winn, H. E., and L. K. Winn. “The song of the humpback whale Megaptera novaeangliae in the West Indies.” Marine Biology 47.2 (1978): 97-114.

Global Warming is Creating an All-Female Sea Turtle Population

By: Konnor Payne, SRC Intern

Unbeknownst to the majority of people, sea turtles have an attribute, like many reptiles, in which the sex of the animal is determined by temperature. This characteristic is called “temperature-dependent sex determination”, which means the sex, of a sea turtle, is determined during the second trimester of incubation. Eggs at 27.7°C or below will become male sea turtles and eggs at 31°C or greater will become female sea turtles. Between these two temperatures (27.7°C and 31°C), the sex, of the sea turtle, is random (Yntema and Mrosovsky, 1982). As a consequence of this basic reproductive component, coupled with global warming increasing the temperature of the nest, a bias has formed in the sex ratios of all sea turtles towards the females (Laloë, 2016). All around the world are reports of 100% female clutches found in critical nesting sites in Barbados, Caribbean, Cyprus and the Mediterranean. The feminization of the sea turtle population has resulted in 85.9-93.5% of all sea turtles developing as females (Laloë, 2016). Projections predict that females will make up over 95% of the hawksbill population by 2045 and 2028 for leatherbacks, but green sea turtles passed this percentage in 2009 (Laloë, 2016).

Figure 1. Sea turtle eggs in an underground nest on a beach.

Although the sex is heavily skewed towards females the mating behaviors of sea turtles has prevented population issues from arising currently. Female sea turtles are not monogamous and will mate with multiple partners during a breeding season allowing fewer males necessary to fertilize all clutches (Pearce & Avise, 2001). Females can store sperm in their bodies for extended periods of time to fertilize multiple clutches at the appropriate time, reducing the frequency in which females need to contact males (Lee, 2008). The two sexes have separate breeding seasons in which the males breed more often than the females (Hays et al., 2014). These combined mating behaviors help to alleviate the problems of a biased sex population, but with the newest IPCC report indicating only increasing future global temperatures, the males will become too rare to replenish the population.

Figure 2. Female green sea turtles on a beach in Maui preparing to make a nest to lay their eggs.

Not only is there a sex bias, but global sand temperatures have begun to rise above the optimal temperature range and into the lethal zone above 32.4°C, depleting the already low populations (Moran et al., 1999). All seven species of sea turtles are classified as critically endangered, endangered or vulnerable by the International Union for the Conservation of Nature. The sand surrounding the clutch of eggs is warmed by the Sun and the atmosphere, as well as the metabolic activity of the eggs (Ackerman et al., 1985). At higher temperatures the metabolic activity of the hatchlings increases, such that the oxygen levels in the nest can decline to suffocate the hatchlings (Ackerman et al., 1985). If a hatchling does not suffocate the heat may cause thermal inhibition of muscle movement preventing them from leaving the nest (Moran et al., 1999). In the past hatchling rates were consistently above 90%, but projections show that by 2100 hatching success will gradually drop to 50.95-78.92% (Laloë, 2017). The heat from the global warming will cause causalities of sea turtles that are already struggling, which will emphasize the female dominance even more.

The future appears grim for sea turtles but there are strategies to help balance the sex ratio and lower heat stress on the hatchlings. The common problem of hatchling death and skewed sex ratio is the nest has too high of a temperature so the methods to solve both problems are to reduce the temperature of the surrounding sand. Sprinkling water at night or over a shaded area of sand consistently lowered the temperature of the sand near the nest by about 2.25°C (Jourdan, 2015). However, the source of water has to be underground via pipes or another method as an above ground source is heated in the day and causes even higher fluctuations in sand temperature than without sprinkling. The area has to be shaded by a tarp or natural cover as moist sand uncovered will increase in temperature in the day more than without water added.  The temperature of the sand decreases the deeper the nest is made, as a nest one meter lower than another is about 1°C cooler (Jourdan, 2015). Once nests are identified they can be dug up and moved deeper into the sand as the hatchlings will still be able to climb out of the nest since larger female sea turtles typically dig deeper nests than the average and have similar emergence rates (Jourdan, 2015). Most sea turtles nest during the warmest months of the year and evidence suggests that they can adapt to the warming temperatures to alter their nesting times to cooler months (Hays, 2014). Although humans have accelerated global warming, that now threatens the existence of all sea turtles, there are methods in which they can be saved.

Work Cited:

Ackerman RA, Seagrave RC, Dmi’el R, Ar A (1985) Water and heat exchange between parchment-shelled reptile eggs and their surroundings. Copeia 1985:703–711

Hays, G. C., Mazaris, A. D., & Schofield, G. (2014). Different male vs. female breeding periodicities help mitigate offspring sex ratios skews in sea turtles. Frontiers in Marine. Science, 1, 43.

Jourdan, J., and M. M. P. B. Fuentes. “Effectiveness of strategies at reducing sand temperature to mitigate potential impacts from changes in environmental temperature on sea turtle reproductive output.” Mitigation and adaptation strategies for global change 20.1 (2015): 121-133.

Juskova, Isabella. “Unsplash.com.” Unsplash.com.

Laloë, Jacques-Olivier, et al. “Climate change and temperature-linked hatchling mortality at a globally important sea turtle nesting site.” Global change biology 23.11 (2017): 4922-4931.

Laloë, Jacques-Olivier, et al. “Sand temperatures for nesting sea turtles in the Caribbean: Implications for hatchling sex ratios in the face of climate change.” Journal of Experimental Marine Biology and Ecology 474 (2016): 92-99.

Lee, P. L. M. (2008). Molecular ecology of marine turtles: new approaches and future directions. Journal of Experimental Marine Biol- ogy and Ecology, 356, 25–42.

Moran KL, Bjorndal KA, Bolten AB (1999) Effects of the thermal environment on the temporal pattern of emergence of hatchling loggerhead turtles Caretta caretta. Mar Ecol Prog Ser 189:251– 261

Pearce, D. E. & Avise, J. C. (2001). Turtle mating systems: behavior, sperm storage, and genetic paternity. Jounral of Heredity, 92, 206-211.

Yntema CL, Mrosovsky N (1982) Critical periods and pivotal temperatures for sexual differentiation in loggerhead sea turtles.

Yong, Mohamed. “Sea Turtle Egg.” Wikipedia.org, 7 Sept. 2007.

 

The Development Plans of Lighthouse Point, The Bahamas

By: Peter Aronson, SRC Intern

Imagine a beach with soft, white sand and pristine, turquoise waters spotted with deep royal blue from the coral patches that lay below.  Scenic rocky cliffs tower over one end of the beach while lush coppice lays 100 feet from the shoreline that young lemon sharks swim along.  This area is called Lighthouse Point.  It sits at the very southeast end of Eleuthera, an island in The Bahamas.  It is a tourist’s paradise, which is why the Bahamian government approved the sale of the area to Disney Cruise Line.

Lighthouse Point was privately owned by an international developer and marketed for large-scale development.  Many large-scale developments have been attempted before on Eleuthera, and many have failed, such as Club Med, the Cape Eleuthera Resort, Whale Point Club, and even the Cape Eleuthera Airport (Project Eleuthera, 2015).  Such failed developments in the past have had poor impacts.  The impacts on nature and the Bahamian economy last much longer than the few years the developments are run for.  There is currently one cruise ship port on Eleuthera, just two miles northwest of Lighthouse Point, which is owned by Princess Cay Carnival Cruise Line.  There is little tourism in the southern part of the island with most resorts and tourist attractions generally increasing in frequency farther north.

Image 1: Eluthera, Bahamas (source: unknown)

Tourism is the largest industry in The Bahamas, accounting for 44.8% of GDP and providing 52.9% of the country’s jobs in 2016 (World Travel & Tourism Council, 2017).  There are positive and negative aspects to tourism.  Tourism in and of itself raises an ethical dilemma.  As Jamaica Kincaid explained in her essay, A Small Place, everyone is a native, every native is a potential tourist, and every tourist is a native from somewhere.  Every native lives a boring, somewhat depressing day to day life which he or she can escape by being a tourist, but most people in the world are too poor to be tourists (Kincaid, 2000).  So, when you go on vacation, the natives there envy you for being able to leave your own boredom and find their daily boredom and depression as a source of pleasure yourself.  Meanwhile, they are not able to escape their own banality and depression and find yours, or anyone’s, as a source of pleasure for themselves.

Despite the disparity in privilege between tourists and residents, there can be positive aspects of tourism when done properly.  Sustainable or responsible tourism involves visiting a place as a tourist with the mindset of having a positive impact on the environment, society, and local economy.  Ecotourism, tourism geared toward experiences with nature, can have a positive impact on the local economy.  It places value on interactions with flora, fauna, and the ecosystems in which they live, giving an economic incentive for local communities to conserve ecosystems. Tourism also can help diversify a local economy, bring extra tax revenue for governments, create jobs, and support local business opportunities. Some of this outside money can go toward projects to support and maintain local infrastructure, schools, and hospitals, that otherwise may not be developed (Barcelona Field Studies Centre, 2018).

There are negative impacts of tourism as well, especially when sustainable tourism is not the focus.  Certain natural areas, such as beaches, forests, mangroves, or coral reefs could be degraded or even completely removed due to development.  There can be a detrimental increase in natural resource use as well.  For example, the average tourist uses three times as much water per day than the average resident in the Caribbean, where water is often already a scarce commodity (Dixon et al., 2001). Tourism can inflate prices for to more than what local communities can afford.  Residents become dependent on tourism as a source of income which can be problematic for many reasons. The jobs created might only be seasonal or temporary, and dependence on foreign income has indirect effects on the tourism industry (not as many Americans will travel to the Bahamas during a recession).  Local job creation is often poorly-paid menial service jobs such as cleaning hotel rooms or waiting at a restaurant. The owners of hotels and restaurants who make much more money are oftentimes foreign investors. Additionally, tourism may influence the local culture, with conflicting lifestyles, changes in individuals’ behaviors, loss of traditional values, and even in some cases, violation of human rights (Barcelona Field Studies Centre, 2018).

Bahamians considered two main options of the sale of the Lighthouse Point land.  One side was that of Disney Cruise Lines, while the other side wanted the area to be sustainably developed into a national park.  The Save Lighthouse Point group stated “While we are focused on conservation, we are also sensitive to the importance of job creation, Bahamian entrepreneurial growth, and sustainable financial opportunities for the people of South Eleuthera and The Bahamas.”  This model focuses on long-term jobs and economic benefits while maintaining the ecological balance and preserving the culture and environment for future generations (Save Lighthouse Point, 2018).

Disney Cruise Lines is aware of the concerns of Bahamians and has considered those concerns in regard to their plans when discussing them with the media.  According to Tribune 242, Disney’s plan would create 150 permanent jobs and an additional 100 temporary jobs during the construction phase, of which, Jeff Vahle, President of Disney Signature Experiences, said “as many as possible” would go to Eleutherans (Sanders, 2018).  Disney demonstrated the benefits of its economic and environmental impact in the Bahamas in a handout, stating that it contributes over $38 million a year to the economy and provides roughly 150 Bahamians with jobs (Sanders, 2018).  It has also donated over $2 million from the Disney Conservation Fund to the Bahamas and has implemented green initiatives, such as using solar power for certain operations at Castaway Cay, a Disney Cruise port farther north in The Bahamas.  It also states its development is going to be much smaller and less dense than originally planned to reduce environmental impact.

Image 2: Luxury cruise ships are a popular form of tourism (image source: Celebrity Cruises)

Opponents of Disney maintain that their plan for a national park goes farther for Bahamians, both environmentally and economically.  They argue that with a national park, there will be 40-70 more permanent jobs with a 146% higher wage. They also state that there will be greater career advancement and increased opportunities for entrepreneurs.  Socially, it would maximize access for Bahamians and be owned entirely by The Bahamas, rather than 19% Disney plans to (Lighthouse Point Partners, 2018).

Disney won the right to purchase and develop Lighthouse Point on October 20, 2018.  It will be important for Disney to demonstrate its care for the Bahamian people by making this development have as low of an environmental impact as possible and supporting the Bahamian economy as much as it can, not only with jobs but with tax revenue, advancement and entrepreneurial opportunities, and high wages. The outcome of this development may have very important, long-term impacts on the South Eleutheran community for years to come.

Work Cited:

Dixon, John & Hamilton, Kirk & Pagiola, Stefano & Segnestam, Lisa. (2001). Tourism and the Environment in the Caribbean.

Kincaid, J. (2000)  A Small Place.  New York, NY.  Farrar, Straus and Giroux.

Lighthouse Point Partners. Economic Development Infographic.  Island School Outreach, October 18, 2018.

Ruins & Ghost Towns – Project Eleuthera. (2015). Retrieved from http://www.projecteleuthera.org/ruins

Sanders, S. (2018). Lighthouse Point Eleuthera Town Hall Handout Reveals Conceptual Site Plan.  Retrieved from https://disneycruiselineblog.com/2018/08/lighthouse-point-eleuthera-town-hall-handout-reveals-conceptual-site-plan/

Sanders, S. (2018). More Details on Disney’s Lighthouse Point Development Plans. Retrieved from https://disneycruiselineblog.com/2018/09/more-details-on-disneys-lighthouse-point-development-plans/

Turner, R., & Freiermuth, E. (2017). Economic Impact 2017 Bahamas. World Travel & Tourism Council.

Save Lighthouse Point – The Vision. (2018). Retrieved from https://www.savelighthousepoint.com/the-vision/

Nudging’ As a Strategy to Instigate Recreational Fishing Compliance

By: Casey Dresbach, SRC Intern

At a primal level, individuals do not generally enjoy being told what to do or how to act. A toddler would much rather prefer to act freely as opposed to being restricted to regimented rules. In a study done by Yulia Starostina, the emotional well-being of preschoolers was examined under strict parenting measures; “forcing” children to learn certain subjects that he/she did not independently express interest in (Starostina, 2013). The results showed an “emotional ill-being” and a strong correlation of mothers’ forcing the development of their children and their educational pathways with their children’s anxiety. The induced anxiety within the population of children studied is surveyed as an indicator to preference of enforcement.

Fishing has served as both a recreational and commercial enterprise for hundreds of years. It provides socio-economic welfare, health benefits, and contributes considerable amounts of protein to communities worldwide. The global estimation of recreational fishing participation is an estimated number of fishers ranging from 220 million to 700 million (Mackay, S., Putten, Sibly, & Yamazaki, 2018). However studies have shown enforcing compliance within recreational fishing is not an easy feat. Fishers naturally work within their own self-interests and such measures are not always taken in favor of the environment. Current strategies to get recreational fishers to act sustainably favor rules and regulations. Yet low levels of adherence to such restrictions set by authorities can directly impact the environment, the resources, and the several species of marine organisms that are extracted daily.

In a piece of literature written by British ecologist Garrett Hardin brought to light, “The Tragedy of the Commons.” (Hardin, 1968). The ocean and its resources combined are characterized as the commons. Such natural resources are described as the commons because generally speaking anyone can extract certain species and failure to comply is often common as well.

In a recent study (Mackay, S., Putten, Sibly, & Yamazaki, 2018), the compliance approach is discussed and scrutinized as the traditional means to fisheries management. Fisheries management in Australia was used as a study area to analyze behavioral insights as a means to target non-compliance of fishers. Traditional enforcement tells recreational fishers what they can and cannot do versus given choices as to what they could possibly do. This study examined the compliance approach within the realm of fisheries management and how as a stand alone mechanism might be vulnerable to nonfulfillment. Difficulty to ensure obedience with this mechanism is characterized by the high number of participants and costs of enforcement, the absence of continual monitoring of fishing activity, and the complications in accurately determining catch levels (Mackay, S., Putten, Sibly, & Yamazaki, 2018). The effectiveness of this traditional method is limited, yet current management is heavily reliant on this compliance approach.

As an additional and perhaps a complementary method, the nudge theory is introduced. “If deterrence relies on ‘shoving’ people to make certain decisions (such as complying with rules), a ‘nudge’ can be thought of as a more subtle way to encourage a decision that is in people’s best interest.” (Mackay, S., Putten, Sibly, & Yamazaki, 2018). Such examples may include but are not limited to how options are presented to people, the tone and language in which it is presented Framing, changes to physical environments, changes to default policy, and the use of social policy and social norms are all entities of potential nudges in recreational fisheries.

Framing is a common tactic used in several arenas. One common example would be in healthcare. “90% of people survive post surgery,” versus “10% die post surgery.” To the patient, the latter does not sound as approachable or appealing as the first. At a cattle and camping station in Western Australia that catch limit is stated to be “no more than 2 fish per day to ensure the sustainability of the wonderful resource. We have a possession limit of 5kg. Catch a fish each day, no need to freeze, there is no comparison to the taste.” (Mackay, S., Putten, Sibly, & Yamazaki, 2018). The message is framed using descriptive versus punitive wording (i.e. the use of the adjective, “wonderful”). 2 fish per day is also lower than the 5kg limit, hence encouraging participants to utilize the lower bag limit as a reference point. (See Figure 1).

Figure 1. Ruler to measure fish size using interactive language markers to encourage fishers to comply with size limits. (Mackay, S., Putten, Sibly, & Yamazaki, 2018)

The article discusses the idea that individuals will do the “right thing” if they feel they are being watched. Changes to the physical environment such as displaying some similar watching-eye initiatives such as a message along with a picture of eyes encouraging fishers to report any instances of non-compliance. Both framing and changes to the environment are discernable and patent to users, making the message hard to avoid.

Figure 2. Using both framing and changes to the physical environment as measures to encourage compliance among fishers. (Mackay, S., Putten, Sibly, & Yamazaki, 2018)

Large-scale initiatives have been put in place through green energy policies, specifically with Tasmanian fishing licensing giving the user the choice to opt in for digital licenses. By digitizing the licensing market, the renewal process would be automatic and potentially reduce the number of cases where fishers do not have a license to fish. By reducing printing costs too, money can be allocated elsewhere making more resources available for other purposes. There are also gray areas or gaps in the system where language or framing can be incorporated. I.e. “if you renew this way, then you sign an agreement to comply with no go areas,” while still offering the possibility to opt out. This would not serve as a forced mechanism, rather an encouraged, giving the user a choice in the matter while making one more environmentally attractive than the other.

Individuals also tend to do or act in ways others do via mimicry. According to the study, social norms and normative messaging with respect to compliance behavior seem to have a positive correlation. The presence of social norms in social media has not only elicited recognition of non-compliance but also an emotional upset among the fishing community. When one instance of non-compliance was shared on Facebook, an argument was circulated through commenting and sharing the post. This feedback can be used by fisheries departments to show the depict a social norm, disapproval of noncompliance.

Figure 3. Summary of potential nudges to be used in fisheries management: simplification/framing, changes to physical environment, Changes to default policy, and social norms and comparison. (Mackay, S., Putten, Sibly, & Yamazaki, 2018)

Interweaving nudges into fisheries management may be a potential to add dimensionality to the punitive enforcement mechanisms that are already in place. Framing, changes to the physical environment, presenting default options, and changes to social norms are nudges that may change the choice environment by making choices more desirable or attractive (See Figure 3). By targeting the overall behavior instead of the individual actions desired outcome of sustainable fishing is more likely. Changing the overall arena in which these actions (i.e. overfishing) are done in makes them less foreseeable. More research should be done looking into the effectiveness of nudge incorporation, as some might serve better in one community versus that of another. Incorporation of the nudge theory into what exists already, as they did in Australian fisheries management, might be a good place to start rather than making a complete shift to one versus the other.

Works Cited

Hardin, G. (1968). The Tragedy of the Commons. Science Mag , 162 (3859), 1243-1248.

Leonard, T. C. (2008). Nudge. Retrieved from Princeton: https://www.princeton.edu/~tleonard/reviews/nudge.pdf

Mackay, M., S., J., Putten, E. v., Sibly, H., & Yamazaki, S. (2018). When push comes to shove in recreational fishing compliance, thing ‘nudge’. Retrieved from Science Direct: https://www.sciencedirect.com/science/article/pii/S0308597X18300939

Starostina, Y. (2013, October 10). Forcing Child Development: Implications for Emotional Well-being of a Preschooler. Retrieved from ScienceDirect: https://www.sciencedirect.com/science/article/pii/S1877042813026724?via%3Dihub

Sunstein, R. C. (2014). Nudging: A Very Short Guide. Retrieved from DASH Harvard: https://dash.harvard.edu/handle/1/16205305

Global Fisheries and the Growth of Greenhouse Gas Emissions

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

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.