by Jake Jerome, RJD Intern

There is no debate that an oil spill is devastating to the marine environment. While many oppose the idea of drilling for oil in the ocean, the fact remains that it is currently happening and will continue into the future. Whether it be from direct drill sites in the ocean or oil tankers traveling the seas, we need to be prepared when there is an accident and oil leaks into the ocean. As our past actions have revealed, we still have a lot to learn about how to cope with an oil spill. Because no one agrees that one method is perfect, it is important to be well informed on some options and seek input so that an educated decision can be made.

Once an oil spill occurs, the first action that should immediately take place is stopping the pollution from the source (5). This can sometimes prove to be difficult as we learned from the Deepwater Horizon Oil Spill in April 2010. Once the oil is stopped, a variety of cleanup methods can be deployed to cope with the disaster. Each cleanup method has pros and cons. A review of possible options follows.

Booms/skimmers:

Booms vary in type but all have the same general design: a sub-surface skirt that prevents oil from escaping below the floating boom, a flotation device, and tension on the boom (2).  The purpose of booms are to contain surface oil within its boundaries so that collection of the oil can take place. Collection of the oil is often carried out by skimmers. Skimmers recover oil without altering its physical or chemical properties and can do so in a variety of ways, including suction and adhesion (5,2). While using booms and skimmers in conjunction is seen as the best option because the oil will be completely removed from the surface, it does face many challenges (2). One of the biggest limitations in the use of this method is surface conditions. Wind and waves encourage oil to carry out its natural tendency, to fragment and disperse itself in the water (2). Rough seas can prevent skimmers from functioning properly and can easily carry oil over the top of booms (2). Another downfall to this method is the ability to get the equipment operating and to the site in a timely manner. Even if the equipment is ready in a few hours, the oil will have had ample time to spread over several square kilometers, making the removal of the oil nearly impossible (2).

In situ burning:

In situ burning of surface oil involves a controlled ignition of spilled oil to essentially burn it off the surface of the water (5). In situ burning is often considered for Arctic or sub-Arctic environments because of their remoteness and sea ice formations that can constrict deployment of other methods (1). In situ burning has been shown to be less effective when used in ice corridors due to the high rate of melting sea ice (1). This reduces the thickness of oil, making it hard to ignite (1). In situ burning also presents environmental problems. Large clouds of black smoke rise from burning sites that not only pollute the air, but can impact communities both on the coast and far inland (2). In situ burning also leaves a residue that can coat coastlines or even worse, sink to cover benthic organisms (2).

Chemical dispersants:

Chemical dispersants are employed on oil spills for the purpose of accelerating the natural dispersion of oil in water (2). The dispersants release the tension between the oil and water and subsequently reduce the droplet size of the oil so it can be distributed in the water column (4). Once in small enough droplet sizes, the oil can be biodegraded by naturally occurring microorganisms (2). Chemical dispersants can quickly break up oil slicks and prevent large quantities of oil from covering coastlines and sensitive habitats. This method is considered to be a favorable option for coping with an oil spill. However, as in the other options, there are negative implications when using this method. There is great concern and debate that adding these chemical dispersants to the ocean is poisoning fish, corals, and other marine species. Goodbody-Gringley et al, found that the popular dispersant Corexit (R) 9500 significantly decreased the larval settlement and survival of two coral species. While this and other studies are telling, more research is needed to fully quantify the affect that dispersants have on the marine environment.

As you can see, choosing the correct method for cleaning up an oil spill can be difficult and is always situation dependent. There are many options that need to be considered before a decision is made, specifically determining the risks associated with each method. Although a quick response time is essential to eliminating a majority of the problems associated with an oil spill, more research needs to be done to help scientists fully understand the ramifications of each method. Overall effectiveness is vital, but unintended consequences must be weighed as well. For the present time these options appear to be the best available, but each should be weighed individually and in comparison to determine the most efficient and effect way to manage an environmental disaster such as an oil spill.

REFERENCES

Bellino, P.W., Rangwala, A.S., Flynn, M.R. “A study of in situ burning of crude oil in an ice channel” Proceedings of the Combustion Institute. Volume 34, Issue 2 (2013): 2539-2546

“Clean Up & Response.” ITOPF. N.p., 2013. Web. 28 Oct. 2013

Goodbody-Gringley, G., et al. “Toxicity Of Deepwater Horizon Source Oil And The Chemical Dispersant, Corexit® 9500, To Coral Larvae.” Plos ONE 8.1 (2013): 1-10

Kujawinski, E.B., Kido Soule, M.C., Valentine, D.L., Boysen, A.K., Longnecker, K., Redmond, M.C. “Fate of Dispersants Associated with the Deepwater Horizon Oil Spill” Environmental Science and Technology. 45. 4 (2011): 1298-1306

Ventikos, N.P., Vergetis, E., Psaraftis, H.N., Triantafyllou, G. “A High-Level Synthesis of Oil Spill Response Equipment and Countermeasures” Journal of Hazardous Materials. 107 (2004): 51-58

by Jacob Jerome, RJD Intern

It is well documented that our climate on Earth is changing and new evidence suggests that marine organisms are adapting. This alteration by marine species is often characterized by adjusting their home range (i.e. where they live). As our climate warms, you would expect marine species to move away from the equator or into deeper water to adjust for the change in temperature. However, not all species are responding in this manner. Unlike other explanations that use biological distinctions among species as the catalyst, Pinsky et al (2013) looked at climate velocities as the driving force.

Climate velocity can be defined as the rate and direction that climate shifts across the landscape. The study aimed to use local climate velocities to explain why all of the species did not move as expected and why some were moving faster than others. North American scientific surveys and bottom-trawl data across nine regions from 1968 to 2011 were reviewed for the study. The data captured 128 million organisms belonging to 360 marine species. From this data, range shifts were measured for each species and then groups were formed based on their geographic region. It was noted that of the nine groups formed, four shifted poleward (i.e. away from the equator) and five shifted south.

Each group was then compared to its corresponding regional bottom temperature changes and it was found that this explained over half of the variation in shifts (It should be noted that one group was omitted due to geographic constraints). While increasing surface temperatures did not promote latitudinal shifts in groups, it did push groups deeper. Although this data is revealing, the researches wanted to examine how individual species responded to climate velocities rather than as a region.

To do this, they first had to recalculate climate velocities to accurately reflect each species’ home range. The results showed that there was variation in the movement from species to species and still a considerable amount did not shift as expected. Over all the species, they found that 74% shifted latitude in the same direction as climate velocity, and 70% shifted depth in the same direction. These results were similar for the species that did not shift as expected. Of those, 73% of shifts to lower latitudes and 75% of shifts into shallower water were explained by climate velocity. The rate at which species shifted was also compared to the climate velocity and it was found that on average, species do not lag behind the speed at which the climate moves.

To ensure that climate velocities were the leading factor in the shifts of species, the researchers added other variables that were related to species characteristics to a multiple regression model. The outcome showed that adding these variables, in addition to climate velocities, only increased the explained variation from 38% to 42%. They concluded that variation in climate velocities has a much greater influence on species shifts than variation in life history.

Understanding these differences in climate velocities may greatly enhance our ability to explain why species are shifting and help predict future events. There is already evidence that climate induced movements of commercially important species has caused conflicts between bordering fishing communities and has made traditional management approaches less effective. Acknowledging the above results will allow scientists and managers to anticipate the scale and magnitude of future events.

by Heather Alberro, RJD Intern

 This article focuses on the issue of ocean acidification and the complexity of its impacts on the marine environment, marine organisms, and on humans societies that depend on the goods and services provided by thriving oceans. The authors of the article stress that, due to the trans-disciplinary nature of the causes and effects of ocean acidification, a more holistic approach should be adopted in order to study this problem more effectively. Any policies addressing ocean acidification, as well as other environmental threats, should be implemented with concern for current as well as future impacts of such policies. This article points out the salience of the 2010 International Workshop in Monaco, a remarkable step towards more holistic research, which brought economists and scientists together in order to combine their contrasting knowledge bases and thus facilitate a multidisciplinary approach to ocean acidification studies.

Ocean acidification has been spurred largely by CO2-increasing anthropogenic activities such as the burning of fossil fuels. The oceans sequester CO2, but as the amounts being taken up increase, ocean acidification occurs, after a series of chemical processes. CO2 sequestration by the oceans does help mitigate the effects of climate change, yet these increases in CO2 sequestration also alter the ocean’s chemistry. Current data on the effects of ocean acidification on ecosystems and organisms is limited and only just beginning to be understood. Some direct effects include physiological disruptions such as changes in behavior and reductions in fertility. However, the indirect effects of ocean acidification are much more difficult to predict and analyze because of the complex nature of ecological interactions. Generalizations are difficult to make because the effects of ocean acidification vary across species, and very few species have been studied. More research is needed on the abilities of organisms to adapt to rising CO2 levels, as well as on the dynamics between ocean temperature, CO2, and other environmental factors, particularly in coastal regions where these dynamics are not so well understood. Further research would help gage the socio-economic effects of ocean acidification on coastal communities dependent on tourism and other goods from the oceans. Research would also greatly facilitate the implementation of effective socio-economic policy.

The article noted the need for a more thorough understanding of the ability of societies to adapt to future changes brought on by ocean acidification. The interactions between societies and the environment are indeed complex and multifaceted, as the attempts to address such interactions should be. Therefore, models designed to study these interactions should be designed to explore their multidimensional nature, not just one side of the relationship, as both ends indeed influence each other. Research programs must be designed which bring together biologists and economists in order to gain more insight into the “bio-socioeconomic” effects of ocean acidification. Effective research and policy take into consideration the various factors that shape particular issues of concern. Therefore, in the case of ocean acidification, one can’t simply study it in isolation from other environmental occurrences such as climate change and biodiversity loss. Often, such issues are very much intertwined. The same idea applies to approaches to research. One must adopt multidisciplinary strategies that incorporate input from various fields of study, ranging from economics and sociology to biology and chemistry. The further these various approaches are integrated in research, the more accurate the data and extrapolations will be, along with their relevance to society.

by Hannah Calich, RJD Intern

Elevated carbon dioxide (CO₂) levels have been shown to not only impact the health of coral reefs, but the health of coral reef associated fish as well. Coral-dwelling gobies are among the most habitat-specialized fish on coral reefs. Since these fish are rarely found outside of their preferred habitat they are a great species to monitor when trying to determine how CO₂ levels influence the habitat choice of reef-fish.

A recent study by Devine and Munday (2013) aimed to determine how short-term exposure to high CO₂ levels influences the habitat preference of coral-dwelling gobies. This study used two goby species, yellow-green gobies, Paragobiodon xanthosomus, who preferentially inhabit only one coral species and broad-barred gobies, Gobiodon histrio, who preferentially inhabit a small number of coral species. The gobies were caught in the wild (Lizard Island, Australia) and moved to aquaria with continuous seawater pumps. The pumps either diffused ambient seawater (as a control, 440 µatm CO₂), or high levels of CO₂ (880 µatm) into the water. The fish remained in the aquaria for 4 days before the experiments began.

Laboratory Olfactory Cue Experiment

A laboratory experiment was used to determine if yellow-green gobies that have been exposed to high levels of CO₂ can distinguish between two olfactory (scent) cues. To do this, a goby that had been exposed to either ambient seawater or high levels of CO₂ was put into a container with two different coral species. The goby could not see the corals, but was able to smell them. The coral species were Seriatopora hystrix (the preferred coral species of yellow-green gobies) and Pocillopora damicornis (a non-preferred coral). The researchers noted which coral species the goby associated with during a 2-minute observation period. If the goby did not approach either coral it was recorded as making “no choice”. This procedure was repeated for 20 control gobies and 19 CO₂ exposed gobies.

Field Habitat Choice Experiment

A field experiment was used to determine if broad-barred gobies could locate an alternative habitat if their host coral died. To begin, a goby that had been exposed to either ambient seawater or high levels of CO₂ was released over a dead colony of Acropora nasuta (the preferred coral species of broad-barred gobies). Surrounding the dead coral was live colonies of A. nasuta and Acropora tenuis (a non-preferred coral species). Each goby had the option of either staying on the dead coral, moving to a live preferred coral, or moving to a live non-preferred coral. After 24 hours the researchers came back to the reef and documented what habitat the goby chose. This procedure was repeated for 20 control gobies and 20 CO₂ exposed gobies.

Laboratory Olfactory Cue Experiment

When yellow-green gobies were exposed to ambient seawater (as a control) they chose to swim towards their host corals 70% of the time. In contrast, the gobies exposed to elevated CO₂ displayed no preference for their host coral. In fact, only 16% of the gobies swam towards the host coral, 42% swam towards the non-host coral, and 42% did not choose a coral.

Field Habitat Choice Experiment

Within 24 hours of being released over a dead host coral, 100% of the broad-barred gobies that were exposed to ambient seawater had relocated to a live preferred coral. In comparison, only 45% of gobies exposed to elevated CO₂ moved to a live preferred coral, 10% moved to a live non-preferred coral, and 45% remained on the dead coral.

Healthy gobies (those raised in ambient seawater) were more attracted to the scent of their preferred coral species than the scent a non-preferred coral species. Additionally, healthy gobies would move from a dead coral to a live preferred coral. However, gobies that had been exposed to high levels of CO₂ were rarely attracted to their preferred coral species. Additionally, when the CO₂ exposed gobies were released on a dead coral they may not leave it.

Results from this study suggest that permanently elevated CO₂ levels may significantly impact the ability of highly specialized fish to locate suitable habitat types following disturbances such as coral bleaching. If a goby is unable to locate a suitable habitat type it will be vulnerable to predation, malnutrition and eventually, death.

Occasionally, a goby may decide to inhabit a non-preferred coral when its preferred coral host dies. This is not an advantageous strategy for the goby as it is adapted to living within its preferred coral. Additionally, since gobies are naturally competitive, if they move onto a new coral they may displace other reef fish that were previously living on that coral. This displacement could theoretically cause a cascading effect that could influence the entire reef.

In conclusion, as CO₂ levels are expected to rise beyond the threshold of many coral communities within the next century, it is not only the corals that are at risk but the coral-associated species as well.

REFERENCE

Devine, B. M., & Munday, P. L. (2013). Habitat preferences of coral-associated fishes are altered by short-term exposure to elevated CO₂. Marine Biology, 160, 1955-1962. doi:10.1007/s00227-012-2051-1

by Jessica Ann Wingar, RJD Intern

Coral reefs are a very important part of the ecosystem, and over the years, the condition of the world’s coral reefs has changed drastically; this condition has not changed for the better. There are many resources that coral reefs provide to the world. Some of these include tourism value and the fact that they provide a natural nursing area for fisheries. A lot of research has been done on corals and what features of a reef, give the reef more monetary value. This research has found some conflicting results. While, some claim that fish biodiversity is more valued than coral biodiversity, some claim the opposite. Although, this research has looked at many aspects of what makes a reef valuable, not a lot has been done with looking at the value of each component of the biological attributes of a reef. This study aimed to look at different levels of biodiversity in fish and corals, in addition to, looking at each condition under different levels of conservation effort. This study also looked at whether or not artificial reefs could be used to cause an increase in ecotourism across the world.

Researchers from the Ben Gurion University of Negev and the Interuniversity Institute for Marine Sciences at Eliat in Israel created a survey to give to divers in the city of Eliat in Israel to see what monetary values they would put on these artificial reefs. The survey presented a number of different biological conditions of artificial reefs and at varying levels of conservation effort. These biological conditions were coral size, coral diversity, fish abundance, coral abundance, varying numbers of fish and corals, and different levels of biodiversity of fish and coral. The survey also asked about how much money they would be willing to pay for each scenario and why they decided on that monetary amount.

This study showed that many of the divers would be willing to pay money for a more diverse environment that could be created by artificial reefs. The greatest motivation for paying more money was for their own enjoyment, but many of them also wanted to pay money to ensure that the reef would continue to exist. The survey showed that the divers wanted to pay more for fish species richness over abundance and they wanted to pay more for coral abundance rather than species richness.

Studies of this nature are very important because they show how recreational water activities can be used as a catalyst for conservation science. This ecotourism can be used as a tool for people to communicate conservation efforts. If people are willing to pay more for high biodiversity, then that is phenomenal because oceans thrive in higher biodiversity. Despite the fact that artificial reefs could help increase conservation awareness, they can sometimes attract certain types of organisms. Thus, creating a community built around them. Artificial reefs and transplantation of reefs hold a lot of potential to increase biodiversity and the health of today’s oceans.

REFERENCE

Polak, O, and Nadav Shashar. “Economic value of biological attributes of artificial coral reefs.” ICES Journal of Marine Science 70.4 (2013): 904-912.