Ocean News – Page 27 – Shark Research & Conservation Program (SRC)

What 19th century stories can tell us about modern fish stocks

March 13, 2015/0 Comments/in Conservation, Ocean News /by aanstett

By Stephen Cain, RJD Intern

Shifting baselines, a term introduced by Daniel Pauly in 1995, occur when successive generations view contemporary environmental conditions as the baseline to measure future change against. The problem with this sort of bounded rationality is that it fails to account for long-term historic trends, and risks myopic decision-making in the greater context. This has been the error of monitoring global fish stocks. In 2001, Jeremy Jackson and several researchers suggested that humans began interacting in coastal ecosystems 10,000 years ago. However, developed nations only recently implemented monitoring fish stocks after the Second World War, with reliable reporting covering the last 40 years. Some of the more robust reporting involve economically important species, and often provide sparse information on non-target species. In the end, our understanding of virginal abundance, and the overall depletion of it, is piecemeal.

Enter Ruth Thurstan and researchers from The University of Queensland, in a partnership with the Australian government. In their recent study on the iconic Australian Snapper (Pagrus Auratus), Thurstan and her team examined two times sets of data: from 1879 to 1939 (development of the fishery), and 1940 to 2003. They devised a novel approach that has extended the baseline for the fishery back to the late 19^th century. They argue that catch rates based on current fishing effort depict a fishery in decline since 1879. By their estimates, Snapper have declined by as much as 90%. Stable catch rates over time may have masked local declines as the fishery expanded its grounds and better technology became available.

Snapper are a species of bony fish that inhabit the rocky reefs of Eastern, Southern, and Western Australia. They range seas from New Zealand to Japan, and can live up to 30 years. In Eastern and Southern Australia, where the team collected data, the recreational Snapper fishery is estimated to be as much as 3 times larger than the commercial fishery. Because the relationship between Australians and Snapper goes back at least 130 years, the social and cultural context matters. According to Thurstan et al., while current gear, size, and allowable catch restrictions are in place, any future efforts to preserve the stock must exercise an understanding of the social ties to Snapper.

Historical ecology, or the study of ecosystems over time, is a discipline that has helped to address some of the issues of shifting baselines. As Thurstan et al. discuss, the trouble with examining their historical data, such as old newspapers, popular literature, and early scientific surveys, is that that information was incomplete, difficult to quantify, or suffered from reporting bias. On the other hand, they suggested that early data yielded qualitative insights that shaped assumptions about fishing effort over a longer time scale.

By piecing missing data together using relevant multiple imputation, the team generated catch rate data (derived from the number of fish, number of fishers, and time spent) that did not statistically differ from complete sources that allowed for cross-reference. The results were encouraging. By using narrative accounts of fish abundance, gear types, and information on the number of fishers of late 19^th century recreational charters, Thurstan et al. were able to expand the data set to 278 entries. This is was a success considering that between all media only 47 records were replete with all 3 of the variables necessary for calculating fishing effort.

Snapper are considered data deficient according to the IUCN Red List. In Queensland, Australia they are considered overfished. The designation from the local governing body there has caused great public debate. As Australia’s governing bodies mull over how best to proceed, similar stories are unraveling worldwide. If the information we have available to us on fishery abundance is at best piecemeal, Thurstan et al.’s research breathes new hope into looking back so that we may go forward.

Nineteenth century narratives reveal historic catch rates for Australian snapper (Pagrus auratus) Ruth H Thurstan, Alexander B Campbell, & John M Pandolfi DOI: 10.1111/faf.12103

Rising Ocean CO2 Levels are Hurting Cephalopods

March 11, 2015/0 Comments/in Conservation, Ocean News /by aanstett

by Jessica Wingar, RJD intern

In the last decade, the concerns of how global climate change is going to affect our planet have grown. One of the main components of what is causing this climate change is the increase in carbon dioxide in our environment. There was a major increase in carbon dioxide in the atmosphere after the industrial revolution. The level of carbon dioxide in the atmosphere has risen from 280ppm to 390ppm. The carbon dioxide from the atmosphere diffuses into the ocean, which has created an increase in carbon dioxide in the ocean. With the increasing carbon dioxide levels in the ocean, the pH of the ocean will decrease leading to many detrimental effects on the animals that live there. It is predicted that by 2300 the carbon dioxide levels in the ocean will be around 1900 μAtm, which will cause the pH of the ocean to drop by 0.77. This decrease in pH will cause extreme changes in the ocean and how organisms develop and survive under these conditions is of utmost importance (Heuer, R., 2014). One of the many classes that has been studied is cephalopoda. The cephalopods include such animals as squid, cuttlefish, and octopus. They are a very important class to ocean trophic levels and to the economy and it is essential to determine what negative effects will occur to them in the coming years (Kaplan, M.B., 2013).

One of these economically important species is Doryteuthis pealeii, the longfin squid. Squid are a critical part of the food chain in the ocean because not only do they serve as prey for many organisms, such as tuna, but they also serve as predators of many organisms. In a study conducted in 2013, this certain species of squid was used. D. pealeii lives in shallow waters in coastal regions. In this study, individuals were taken from Vineyard Sound, Massachusetts on two separate occasions during their breeding seasons which lasts from May to August. The aim of this study was to calculate the difference in mantle size, statolith size, statolith characteristics, and hatching time between control embryos and embryos at an elevated carbon dioxide level of about 2200 μAtm. This is slightly above the predicted levels for the year 2300. The study found that in both trials, embryos hatched later in the carbon dioxide treatment than the control embryos. For example, in the first trial on the first day of hatching, 62.6% of embryos hatched, whereas only 0.7% of the embryos with increased carbon dioxide hatched. The negative effects of this delay may be that there is an increased chance for predation.

Picture 1: Embryo hatching times for both trials

In addition to the hatching time, there were also many other negative changes in other parts of the squid. When the mantle length was looked at between the two conditions, the mantle was significantly shorter when the squid was reared in the carbon dioxide conditions. With a shorter mantle, the squid has less ability to move. Therefore, a shorter mantle can lead to slower swim speeds and lower migration causing a smaller chance of survival. Squid also have statoliths, which are calcified structures that are critical in balance and how the animal moves in the water. Seeing as these are calcified structures, their formation is greatly related to the acid content in the water. In this study, it was found that the statoliths of the squid in carbon dioxide had decreased surface area and a greater likelihood of abnormal shape and abnormal porosity. With decreased function of the statolith, the squid cannot orient itself the correct way in the water and again has decreased survival (Kaplan, M.B., 2013). Along with this type of cephalopod, cuttlefish also show a change in an inner calcareous structure in increased carbon dioxide conditions.

Picture 2: Average statolith surface area in the control treatment vs. the carbon dioxide treatment

Some cuttlefish have a calcareous structure called a cuttlebone that is located dorsally that goes from just behind the head to the end of its body. The purpose of this bone deals with buoyancy. During the day, the chambers of the cuttlebone are filled with fluid, which make the cuttlefish able to sink, and at night this fluid is expelled, which causes the cuttlefish to stay in the same place in the water column. A study done on Sepia officinalis, the common cuttlefish, looked at morphological changes in the cuttlebone in a carbon dioxide rich environment. In this study they found that carbon dioxide exposed cuttlebones had significantly less height and length, but had a 20-55% increase in mass. The shorter height can be accounted for by the fact that the lamellae in the cuttlebone in the carbon dioxide treatment were a lot closer together, compacting the cuttlebone. In addition, the inner pillars of the cuttlebone were found to have doubled in thickness, showing a build up of carbonate and an increase in mass. A heavier cuttlebone is detrimental to a cuttlefish because in order for that structure to control buoyancy it needs to be as light as possible; the cuttlefish will not be easily able to move up the water column because it will take more work to make the animal neutrally or positively buoyant. In addition, it will be more difficult for the cuttlefish to maintain a position in the water column while hunting, which could cause starvation in the organism (Gutowska, M.A., 2010).

Average cuttlebone measurements in the control vs. carbon dioxide treatments

Research into the consequences of ocean acidification is increasingly necessary in order to determine what will happen to the ocean in the next few hundred years. The spike in the carbon dioxide content in the oceans has been directly caused my humans and it is imperative that now something is done to slow down this increase.

References
Gutowska, M.A., Melzner, F, Pörtner, H.O., and Sebastian Meier. (2010). Cuttlebone calcification increases during exposure to elevated seawater pCO2 in the cephalopod Sepia officinalis. Marine Biology, 157 (7): 1653-1663.

Heuer, R.M., and Martin Grosell. (2014). Physiological impacts of elevated carbon dioxide and ocean acidification on fish. American Journal of Physiology, 307 (9): R1061-R1084.

Kaplan, M.B., Mooney, T.A., McCorkle, D.C., and Anne L. Cohen. (2013). Adverse Effects of Ocean Acidification on Early Development of Squid (Doryteuthis pealeii). PLOS ONE, 8 (5): 1-10.

Offshore Windmill’s Impact on the Marine Environment

March 4, 2015/0 Comments/in Conservation, Ocean News /by aanstett

by James Keegan, RJD intern

Global demand for renewable energy is increasing as nations strive to decrease their carbon emissions, pollution, and dependence on non-renewable resources like coal or oil. Because of its energy output and potential to compete in energy markets, wind energy may be the most promising renewable energy (IEA 2013). Consequently, wind energy has been rapidly expanding, reaching a capacity in 2012 that was 5 times greater than the capacity in 2005 (IEA 2013). Expectations for offshore wind energy are particularly high, as wind conditions are often stronger and more stable over sea (Bergström et al. 2014). Moreover, offshore wind farms allow for higher total levels of energy production and larger windmill units, which may be transported and constructed more easily (Bergström et al. 2014). Offshore wind farms also appease dissenters who contest that the visual disturbance caused by windmills ruins the aesthetics of local landscapes. As technology has advanced, the average capacity of turbines and size of offshore wind farms have been increasing, and they are being installed in deeper waters further from the coast (Bailey et al. 2014). By the end of 2013, operational wind farms were in an average water depth of 16 meters (~52 ft.) and 29 kilometers (~18 miles) from shore in Europe (Bailey et al. 2014). With such an increase in the encroachment on the marine environment, the focus on offshore wind farms’ impact on the local marine ecosystem continues to grow as well.

Windmill park in Oresund between Copenhagen, Denmark and Malmo, Sweden. (Photo source: Wikimedia Commons)

Although conservationists are studying the impact of offshore wind farms, the novelty of the technology and construction processes make it difficult to identify and quantify all of the stressors. The first commercial scale offshore wind farm, Horns Rev 1, only became operational in 2002 (Bailey et al. 2014). Moreover, the impact offshore wind farms have depends on local ecosystems, which can vary wildly. However, the understanding of the potential effects of offshore wind farms on marine ecosystems, as well as marine biodiversity, is steadily improving as empirical evidence from operational wind farms accumulates (Bergström et al. 2014). The two phases of offshore wind farms, construction and operation, have different potential effects, and these effects differ among species, depending on their likelihood of interaction with the structures and cables, sensitivities, and avoidance responses (Bailey et al. 2014). The major environmental concerns related to offshore wind farms are increased noise levels, risk of collisions, changes to benthic and pelagic habitats, alterations to food webs, pollution from increased vessel traffic, bird collisions, electromagnetic fields, and release of contaminants from seabed sediments (Bailey et al. 2014). However, offshore windmill farms also benefit the local ecosystem by acting as artificial reefs as well as de-facto marine reserves, providing protection against fishing pressures. With both beneficial and adverse contributions to the marine environment, offshore wind farms continue to intrigue conservationists.

Figure 2: An overview of the main pressures from offshore wind farms during the operational phase. Expected effect on the local abundance of marine organisms is indicated as (+) aggregation/increase, or (−) avoidance/decrease (Bergström et al. 2014).

The two fundamental stages of the development and use of offshore wind farms provide their own challenges and have their own environmental concerns. The construction phase is likely to have the greatest impact on marine mammals, and the activities of greatest concern are pile driving and increased vessel traffic (Bailey et al. 2014). Pile driving is the mechanical process of imbedding poles into sediment to provide foundational support for the proposed structure. Pile driving is currently the most common method used to secure turbine foundations to the seafloor, and it emits a considerable amount of noise (Bailey et al. 2014). The sounds emitted during pile driving could potentially cause hearing damage, mask calls, or displace animals as they leave the area to avoid the noise (Bailey et al. 2014). Moreover, the noise produced by pile driving can cause mortality and tissue damage in fish (Bergström et al. 2014). Alternatively, wind farms can use gravity foundations, which anchor windmills essentially by means of their own weight. The intensity of the noise caused by their installation is low, and animals are likely to return soon after the exposure has ended, thus lowering the impact (Bergström et al. 2014). However, this type of installation does cause high sediment dispersal due to dredging, or the removal of underwater sediments, but typically organisms inhabiting the sites of gravity foundation wind farms are tolerant of turbidity (Bergström et al. 2014). In addition to the installation of the windmills themselves, the increased vessel traffic associated with surveying and installation activities also creates the risk of collision and noise disturbance to marine mammals, sea turtles, and fish (Bailey et al. 2014). Although the construction phase of offshore wind farms only creates problems for the marine environment, its impact can be curtailed by avoiding significant habitats and seasons.

The operational phase of offshore wind farms requires a more challenging and complex assessment because of the duality of its environmental impacts. Like the construction phase, the operational phase raises concerns about acoustic disturbances, but from electricity generation and boat traffic for service and maintenance. The acoustic disturbances caused by the operation of the windmills are within the hearing range of fish and mammals, but underwater sound levels are unlikely to reach dangerous levels or mask acoustic communication of marine mammals (Bergström et al. 2014), (Bailey et al. 2014). Transmission cables transporting the generated electricity produce electromagnetic fields, which can affect cartilaginous fish, like sharks, which use electromagnetic signals in detecting prey (Bergström et al. 2014). The electromagnetic fields could also disturb fish migration patterns by interfering with their capacity to orientate themselves in relation to Earth’s magnetic field (Bergström et al. 2014). However, the production of these electromagnetic fields can be mitigated by proper cable design (Bergström et al. 2014). The major concerns for this phase of offshore wind farms are seabird mortality caused by collision with the moving turbine blades and seabird displacement from key habitats as a result of avoidance responses (Bailey et al. 2014). These issues can affect birds migrating through the area as well as those that breed or forage in the vicinity.

Although the operation of offshore windmills has negative impacts on the local ecosystem, these impacts may be matched or even outweighed by the positive ones that wind farms also introduce. Windmills can produce habitat gain by acting as artificial reefs, thereby enhancing local species abundances and biodiversity (Bergström et al. 2014). Moreover, studies have found that fish are seasonally attracted to wind farms with high fidelity, and that seals are potentially using wind farms as foraging sites (Reubens et al. 2014), (Russell et al. 2014). However, increased species abundance can be problematic when some species benefit more than others, or when wind farms introduce non-indigenous species (Bergström et al. 2014). Another major positive contribution wind farms make to the local ecosystem is fisheries exclusion. Although wind farms restrict fisheries’ intrusions for the safety and preservation of the farm itself, the local species benefit, both targeted species and non-targeted bycatch species (Bergström et al. 2014). This exclusion also prevents bottom trawling, the dragging of nets on the sea floor, so benthic organisms benefit as well (Bergström et al. 2014). Moreover, an abundance of fish caused by the exclusion of fisheries may have spillover, and surrounding areas may also see an increase in species abundance (Bergström et al. 2014). There may also be opportunities in the future to combine offshore wind farms with open ocean aquaculture (Bailey et al. 2014). With notable contributions to biodiversity and species abundance, windmill farms mitigate their negative impacts on the local environment.

With an increasing demand for renewable energy and, by extension, wind energy, offshore wind farms will continue to develop and grow around the world. Therefore, an increasing understanding of the impacts offshore wind farms have on marine environments is needed. Currently, investigations show that the construction phase consistently inflicts negative impacts, and that pressures during the operational phase may impose both negative and positive effects, depending on local environmental conditions as well as prevailing management targets (Bergström et al. 2014). However, confidence in these findings is not perfect because of their variable nature and because of the relatively short time frame offshore wind farms have operated, limiting data collection. In order to gain a better understanding of potential impacts, conservationists need to further investigate population dynamics and migrations in areas that already have wind farms and areas that are under consideration for them.
References:

IEA (2013), World Energy Outlook 2013, IEA. doi: 10.1787/weo-2013-en
Bergström, L., Kautsky, L., Malm, T., Rosenburg, R., Walberg, M., Capetilli, N. Å., and Wilelmsson, D. (2014) Effects of Offshore Wind Farms on Marine Wildlife – A Generalized Impact Assessment. Environmental Research Letters, 9. doi:10.1088/1748-9326/9/3/034012

Bailey, H., Brookes, K.L., and Thompson, P.M. (2014) Assessing Environmental Impacts of Offshore Wind Farms: Lessons Learned and recommendations for the Future. Aquatic Biosystems, 10:8. doi:10.1186/2046-9063-10-8

Reubens, J.T., Degraer, S., and Vincx, M. (2014) The Ecology of Benthopelagic Fishes at Offshore Wind Farms: A Synthesis of 4 Years of Research. Hydrobiologia, 727: 121-136. doi:10.1007/s10750-013-1793-1

Russell, D.J.F., Brasseur, S.M.J.M., Thompson, D., Hastie, G.D., Janik, V.M., Aarts, G., McClintock, B.T., Matthiopoulous, J., Moss, S.E.W., and McConnell, B. (2014) Marine Mammals Trace Anthropogenic Structures at Sea. Current Biology, 24(14): R638- R639. doi:10.1016/j.cub.2014.06.033

The Understanding of Giant Clams’ Contributions to Coral Reef Health Continues to Grow

February 27, 2015/0 Comments/in Conservation, Ocean News /by aanstett

by James Keegan, RJD intern

Coral reefs suffer from a multitude of problems, such as global warming and ocean acidification, which can be deadly for the reefs. Other issues, like losing individual species, although troublesome, do not garner the same attention because they do not cause as much harm. However, each reef organism has their role to play in the ecosystem, and because of their wide range of functions and highly threatened status, giant clams may deserve special consideration. Currently, the 13 known species of giant clams live in the Indo-West Pacific. The largest species, Tridacna gigas, can reach shell lengths of 120 cm (~3 ft 11 in) and weights in excess of 200 kg (~441 lbs). Because of their high tissue mass and heavy calcified shells, humans have been using them for both food and building material. Along with this demand, habitat degradation, technological advances in exploitation, and expanding trade networks have decreased giant clam numbers throughout their range. Moreover, giant clams are especially vulnerable to this sort of depletion because of their late sexual maturity, sedentary lifestyle, and external fertilization through broadcast release of reproductive cells. Fertilization success requires a sufficient number of spawning individuals, and low densities result in reduced, or zero, juvenile survival and eventual population collapse.

Although giant clams are protected under international law, their stocks are declining rapidly in many countries, and local extinctions are occurring. Such losses could have an unknown number of consequences because giant clams’ significance in coral reefs is not well understood. Giant clams serve several ecological functions in coral reef ecosystems, but conservationists have not previously assessed the extent to which these functions impact the local ecosystem. To rectify this, Neo et al. 2015 used data from literature and their own studies to determine a more accurate assessment of the role giant clams play in coral reefs.

Neo et al. 2015 sought out to properly establish and quantify giant clams’ contribution to reef ecosystems. They used the data obtained from the literature to consolidate information as well as calculate parameters like population density, size distribution, biomass, shell weight, and production. They found that giant clams provide food for local organisms directly through their tissue and indirectly through the discharge of feces, gametes (reproductive cells), and zooxanthellae (photosynthetic algae). Other organisms can also take up and host the zooxanthellae that giant clams expel.

Figure 1: Maximum net primary productivity (NPP) of different reef flora and fauna, measured in terms of net oxygen production (units are in terms of grams of oxygen produced per meter squared per day). The two giant clam species listed have the second and third greatest NPP, beating out hard corals and most algae. (Neo et al. 2015)

Furthermore, the shells of giant clams provide a surface for colonization by epibionts, organisms that live on the surface of other living organisms. An example of an epibiont would be a barnacle. Giant clams serve as nurseries and refugees for fish on the reef as well, and they can even shelter anemone fish in the absence of host anemones. The space between the outer wall of the clam’s soft body and its internal organs, known as the mantle cavity, also provides a habitat for symbiotic organisms.

Figure 2: Epibiota diversity among giant clam species. The ones shown on the giant clams in each picture are: (a) another clam (b) hard coral (c) algae and (d) a variety of encrusting organisms. (Neo et al. 2015)

Moreover, giant clams counteract eutrophication, the nutrient enrichment of water that typically leads to excessive algal growth, by filtering the water and sequestering nutrients. Giant clams also contribute to the topographic relief of reefs, which in itself modifies or creates habitat and affects local water flow. This alteration in water flow benefits the reef by hindering sedimentation and improving food influx. Finally, giant clams make their shells out of calcium carbonate, the same material hard corals use for their skeletons, so their shell material can be incorporated into the reef framework.

Giant clams benefit coral reefs in many ways, and their presence is indicative of reef health. Unfortunately, overfishing has put giant clams under great pressure, and their local extinction could be detrimental to coral reefs. By enhancing the understanding of giant clam contributions to coral reefs, Neo et al. 2015 hope to reinforce the case for their conservation.

References

Neo, M.L., Eckman, W., Vicentuan, K., Teo, S.L.-M., Todd, P.A. (2015) The Ecological Significance of Giant Clams in Coral Reef Ecosystems. Biological Conservation, 181: 111-123. doi:10.1016/j.biocon.2014.11.004

The Consequences of the Indo-Pacific Lionfish invasion into Atlantic Waters

February 26, 2015/0 Comments/in Conservation, Ocean News /by aanstett

by Laurel Zaima, RJD intern

The introduction of an invasive species into a foreign ecosystem has dire and often unforeseen consequences. An invasive species is considered any living organism that is not native to the ecosystem and causes harm to the local environment (“Invasive Species”). Non-native organisms alter the ecosystem, which affects the native species, habitat structures, human health, and even our economy. Invasive species are actually one of the leading threats to native wildlife and are the primary risk to approximately 42% of threatened or endangered species (“Invasive Species”). The inevitable alteration to the ecosystem from the invasive species causes commercial, agricultural, and recreational activities to suffer. The current invasion of the lionfish is an extremely disconcerting issue that has been damaging and disrupting the native species and the balance of the ecosystem.

Lionfish are originally from the Indo-Pacific and Red Sea, but they have recently invaded Atlantic waters near Florida and the Caribbean and into the Gulf of Mexico (“Lionfish- Pterois volitans”). Lionfish were some of the most commonly imported tropical fish for aquariums; however, owners would often release them into the Atlantic when they grew too large for their aquariums (“Venomous Lionfish”). Lionfish were first reported off Florida’s Atlantic Coast near Dania Beach in 1985, and since then the lionfish populations have exponentially increased and spread (“Lionfish- Pterois volitans”). [Picture 1: In the summer of 2001, this lionfish was found about 40 miles off the coast of North Carolina.]

Lionfish have an extremely high success rate for a variety of reasons. Since the lionfish are not natively found in the Atlantic waters, they have no natural predators in this region to control their populations. Lionfish have 18 venomous spines that are used as a defense mechanism (“Lionfish- Pterois volitans”). Any native predators that have unknowingly tried to consume this new food source has fallen victim to their venomous spines. The lionfish also breed at a very rapid pace because both males and females sexually mature in less than a year and have the ability to spawn 12,000 to 15,000 eggs every four days in warm climates (“Lionfish- Pterois volitans”). Lionfish have quickly spread their populations throughout the Atlantic because are tolerant to a variety of habitat conditions. They have been found in shallow waters and in depths up to 1,000 feet; they can withstand temperatures as cold as 48 to 50 degrees; and they can survive in low salinities for short periods of time (“Lionfish- Pterois volitans”). Lionfish have easily assimilated into Atlantic waters, but the main concern about the lionfish is their broad diet that negatively impacted the native ecosystem.
Lionfish hurt the wellbeing of coral reefs because of their massive predation of native species, and they compete with the native predators for food. As a predatory reef fish, lionfish are known to prey on more than 70 marine and invertebrate species including yellowtail snapper, Nassau grouper, parrotfish, banded coral shrimp, and cleaner species (“Lionfish- Pterois volitans”). These feeding habits drastically reduce the native populations in coral reefs, which result in negative effects on the reef habitat. Some of the species targeted by the lionfish play important ecological roles in limiting the amount of algae on the reefs, and without their presence, the coral reefs can be overgrown by algae (“Lionfish- Pterois volitans”). Lionfish often target the native juvenile species as another source of food. Albins and Hixon (2008) found that lionfish caused significant reductions in the recruitment of native fish by an average of 79% over a 5-week study period. Targeting the coral-reef fish at the early stages of life declines the abundance and diversity of the local fish (Albins and Hixon, 2008). Complete eradication of lionfish from the Atlantic and Gulf of Mexico is probably unobtainable; however, efforts need to be made in order to control their rapidly growing populations.
There are a couple solutions that can be implemented towards the extermination of the invasion of lionfish. The first step that must be taken is to educate the public about lionfish in the Atlantic and Gulf of Mexico and the damaging effects they have on the natural ecosystem. Local fishermen should be encouraged to remove any lionfish that they catch to help limit the negative impact this species has on the native marine life (“Lionfish- Pterois volitans”). Commercial fisheries and recreational fishermen should also be encouraged to target lionfish as a main catch (Hixon, Albins, Redinger, 2009). When filleted and cooked properly, lionfish are very delicious. This species could be profitable to fisheries if they target to catch and sell them as a form of sustainable seafood. The recovery and maintenance of healthy populations of native predators, such as large grouper and sharks, can help regulate lionfish populations as well (Hixon, Albins, Redinger, 2009). Lionfish population controls can be regulated on a regional and nation wide level. Regions need to ensure that they are prioritizing the removal of lionfish from key areas such as marine protected areas (MPAs), high tourist areas, spawning aggregation sites, and nursery areas (Akins, 2012). These regions are extremely vulnerable to the lionfish, and an invasion by these predators could be detrimental to the recruitment and survival of local reef fish. A nation wide control effort of the lionfish in the Atlantic could help to reduce the lionfish in mass quantities (Akins, 2012). However, in order to monitor the progress of the nation’s control plan, commercial and recreational fishermen and scientists need to continue to report and document the lionfish caught in order to gauge the effectiveness of the implemented programs (Akins, 2012). [Picture 2: A Virgin Islands biological technician examines the Indo-Pacific lionfish captured off the coast.] By enacting some of these invasion control plans, the lionfish population can be better regulated, and the coral reefs and native species would be better preserved.
Works Cited
Akins JL (2012) Control Strategies: Tools and Techniques for Local Control. Pages 24-47 in: JA Morris Jr. (ed.) Invasive Lionfish: A Guide to Control and Management. Gulf and Caribbean Fisheries Institute Special Publication Series Number 1, Marathon, Florida USA. 113 pp.
Albins MA, Hixon MA (2008) Invasive Indo-Pacific lionfish Pterois volitans reduce recruitment of Atlantic coral-reef fishes. Mar Ecol Prog Ser 367: 233-238.
Hixon M, Albins M, Redinger T. “Lionfish Invasion: Super Predator Threatens Caribbean Coral Reefs.” NOAA’S Undersea Research Program. NOAA, 8 Mar. 2009. Web. 4 Feb. 2015.
“Invasive Species.” National Wildlife Federation. n.p. n.d. Web. 4 Feb. 2015.
“Lionfish- Pterois volitans.” Florida Fish and Wildlife Conservation Commission. n.p. n.d. Web. 4 Feb. 2015.
“Venomous Lionfish Invade South Florida Waters.” Lionfishhunters.org. n.p. 2010. Web. 4 Feb. 2015.

Exploitation and Cooperation by Cleaner Wrasse

February 20, 2015/0 Comments/in Conservation, Ocean News /by aanstett

By Laura Vander Meiden, RJD Intern

The relationship between cleaner wrasse and reef fish has long been one of the textbook examples of mutualism, a partnership in which both individuals benefit. In this relationship, the cleaner wrasses set up “cleaning stations” where they eat parasites and dead skin cells off of willing reef fish. The reef fish benefit through the removal of those parasites, while the wrasses gain a food source. However, the cleaner wrasses’ preferred food source is actually a type of mucus given off by the reef fish. Because of this, the cleaner wrasses sometimes deviate from mutualistic parasite removal by eating mucus given off by the client (Grutter et al 2003). This cheat disrupts the balance of the symbiotic interaction making participation detrimental to the reef fish that need the mucus for protection from bacteria and parasites. If this cheating behavior were to become the norm for cleaning wrasses, the reef fish would eventually stop participating because the partnership is no longer beneficial for them. Fortunately, both cleaner wrasse and reef fish have developed behaviors that limit the detrimental effects of cheating and keep the mutualistic relationship stable.

A cleaner wrasse and a moray eel. (picture by Albert Kok from wikimedia commons)

Non-predatory reef fish employ several different behaviors to keep the cleaner wrasse from sneaking bites of mucus. If there are multiple cleaner wrasse in the area, a fish who has had mucus stolen will immediately leave and visit another wrasse’s cleaning station. If there is only one wrasse in the area, the exploited fish will end the cleaning session and aggressively chase the wrasse. Both of these behaviors temporarily reduce the wrasse’s ability to feed by the termination of the session, and in the case of chasing behavior, are energetically intensive for the wrasse. Bshary et al (2005) has provided evidence that these two behaviors actually teach the wrasse to feed against their food preferences, limiting their mucus stealing. These two behaviors are called alternative control behaviors; they are termed such because non-predatory reef fish, the ones targeted by exploitation, have no option to cheat in this partnership, so instead they work to affect the outcome by these alternative means. Predatory reef fish on the other hand can reciprocate cheating behavior by eating the cleaner wrasse, it is likely for this reason that cleaner wrasse have not been observed to cheat in interaction with predatory reef fish (Bshary 2005).

These alternative control behaviors do not completely eradicate the cheating behaviors of cleaner wrasse. Instead, the cleaners have the ability to switch back and forth between mutualistic and parasitic behavior, based on the circumstances (Gingins 2013). The experimental conditions that were found to affect the cleaner’s decision to exploit were the level of temptation to cheat and the extent to which the partner employed alternative control behaviors. A higher level of temptation combined with a lack of controlling behaviors led to the highest level of exploitation while low temptation no matter the level of control behaviors utilized led to increased mutualism (Gingins 2013). Furthermore this ability to distinguish between different conditions was unique to cleaner wrasses. When a pinstripe wrasse, a non-cleaning wrasse species, was tested in the same situation it failed to adjust its behavior to the conditions(Gingins 2013). This is likely due to the fact that non-cleaning species have no reason to have evolved the cognitive capacity to decide when or when not to cheat.

Kelp bass and a cleaner wrasse. (Photo by Tomarin – wikimedia commons)

The back and forth between cleaners and reef fish may seem a bit excessive for what is supposed to be a mutually beneficial relationship. However, one has to realize that both the cleaner wrasse and the reef fish are focused on their own best interests. When these interests coincide with one another, the two are able to interact to the mutual benefit of all involved. When these interests do not coincide, such as when a cleaner wrasse attempts to cheat and eat mucus, the cooperation between the two will either disappear or strategies such as the reef fishes’ alternative control behaviors will develop. These behaviors decrease the benefits of the wrasse’s cheating behavior until it is in its own best interest to return to eating only ectoparasites and dead skin cells. Ultimately, the evolution of alternative control behaviors in this system has allowed for the continuance of this mutualistic behavior.

Works Cited

Bshary, R., & Grutter, A. S. (2005). Punishment and partner switching cause cooperative behaviour in a cleaning mutualism. Biology Letters, 1, 396-399.

Gingins, S., Werminghausen, J., Johnstone, R. A., Grutter, A. S., & Bshary, R. (2013). Power and temptation cause shifts between exploitation and cooperation in a cleaner wrasse mutualism. Proceedings of the Royal Society B: Biological Sciences, 280, 20130553-20130553.

Grutter, A. S., & Bshary, R. (2003). Cleaner wrasse prefer client mucus: support for partner control mechanisms in cleaning interactions. Proceedings of the Royal Society B: Biological Sciences,270, S242-S244.

Summary of “Competitive interactions for shelter between invasive Pacific red lionfish and native Nassau grouper”

February 11, 2015/0 Comments/in Conservation, Ocean News /by aanstett

Hannah Armstrong, RJD Intern

Invasive species have the potential to negatively effect normal ecological function in any environment. Marine biological invasions are increasingly common, most notably that of the Pacific red lionfish (Pterois volitans). While the lionfish invasion and its direct effects on native fish communities has been well researched, there has been little documented evidence regarding non-predatory interactions. In a 2014 study by Raymond, Albins and Pusack, they observed whether Pacific red lionfish and Nassau grouper, two species that occupy similar habitats, compete for shelter and whether or not the competition is size-dependent.

Pacific red lionfish (Pterois volitans) have been reported in the Atlantic Ocean since the mid-1980s and now pose a threat to the western Atlantic and Caribbean coral reef systems. As small-bodied predators, they are capable of significantly reducing the abundance and diversity of native fishes via predation. Nassau groupers (Epinephelus striatus), despite being regionally endangered, are a larger predator found throughout the lionfish’s invasive range. Because these two species use similar resources and compete for similar habitats, it is important to understand how they interact and what may result from their competition.

The invasive Pacific red lionfish, Pterois volitans. (Source: Smithsonian Marine Station at Fort Pierce)

In order to investigate how Pacific red lionfish and Nassau grouper affect each other’s behavior, the three scientists set up an experiment to compare their distance from and use of shelter when in isolation versus when both species were in the presence of each other with limited shelter. The two species were first held in separate cages with partitions to allow for isolation periods lasting 24 hours, and interaction periods lasting 48 hours, with each cage containing a shelter that the scientists constructed. The trials were based on size-ratio treatments: first they observed similarly sized lionfish and Nassau grouper, then they observed a juvenile lionfish and a substantially larger juvenile Nassau grouper, and lastly they observed an adult lionfish and a much smaller juvenile grouper. Finally, to test for predation between the two species, they incorporated a prey fish in some of the trials.

The native Nassau grouper, Epinephelus striatus. (Source: IUCN Red List)

Upon statistical analyses, Raymond, Albins and Pusack eventually came to two conclusions regarding the interactions between these two species, and specifically Nassau grouper avoidance behavior: first, they found that when Nassau grouper interacted with smaller lionfish, they avoided them by moving further from the shelter occupied by lionfish, and by using the shelter less often, and second, they found that when Nassau grouper interacted with similarly sized lionfish, they avoided them by increasing their proportion of shelter use, and by avoiding the part of the experimental cage where lionfish were consistently present. The scientists ultimately found that the Nassau grouper significantly changed position relative to shelter in the presence of lionfish, however the lionfish did not change their positioning upon interacting with the Nassau grouper. This demonstrates how they have a tendency to compete for limited shelter, and the manner in which the Nassau grouper avoid lionfish is size-dependent.

Configuration of experimental cages used in this study.

While this study highlights the competitive interactions for shelter between invasive Pacific red lionfish and Nassau grouper, it is important to note that it was performed in a laboratory setting. For future conservation efforts, it will be critical to consider how this might apply in a natural reef habitat, and whether or not this competition could lead to lionfish being a dominant predator rather than the native Nassau grouper, a shift that may result in trophic cascades.

Reference:

Raymond, WW, Albins MA, Pusack TJ. Competitive interactions for shelter between invasive Pacific red lionfish and native Nassau grouper. Environ Biol Fish (2015) 98:57-65. 31 January 2014.

Fish are Friends and Food: The rise of the US federal seafood certification

February 6, 2015/0 Comments/in Conservation, Ocean News /by aanstett

by RJD Intern Daniela Ferraro

As appetite increases, people are looking towards federally managed fisheries to provide a seafood certification system. With rising levels of overfishing, habitat destruction, and mismanagement, there has been an emphasis placed upon fishing regulations and sustainable fishing practices (Jackson et al 2001). This began with adjustments to the Magnuson-Stevens Fisheries Conservation and Management Act (MSA) in 2006, giving the National Marine Fisheries Service (NMFS) and Regional Fishery Management Councils permission to establish annual catch limits. Fishing limits are an attempt at keeping stocks from being overfished. Sustainable fishing is the process of maintaining a balance in favor of the number of fish reproduced versus stocks fished. Unfortunately, stocks are not rebuilding and continuing to decline in number (Rothschild et al).

400 tons of Chilean jack mackerel caught in a purse seine. Photo source: Wikimedia Commons

The federal government’s jurisdiction reaches as far as the end of the Exclusive Economic Zone from 3 to 200 miles offshore. In the past 8 years, from 2007 to 2014, the federal government has worked to develop a framework for seafood import and certification as well as an eco-label program. These guidelines abide by the standards set in the MSA with input from eight of the Marine Fisheries Advisory Committee meetings (Sasser et al 2006). Currently, there are at least 200 consumer guides and 70 certifications and eco-labels that focus on wild caught fisheries and aquaculture. The largest certification program is the Marine Stewardship Council (MSC), which acts to align fisheries based on a specific set of standards that support sustainability. MSC’s guidelines take the status of the fishery, efficacy of management, and the impact to habitat into effect when assigning certifications (Christian C 2013). In developing countries, MSA has certified fishing fleets involved in fisheries improvement projects (FIPs) to encourage sustainability. While FIPs relay the means towards sustainable fishing, these fleets don’t meet MSA standards (Bush et al). Large corporations in the United States, such as McDonald’s and Walmart, along with the European Union recently agreed to buy only MSC-certified seafood (MSC 2013).

The MSC Ecolabel, Photo source: Wikimedia Commons

Opposition comes in the form of Senator Lisa Murkowski’s Responsible Seafood Certification and Labeling Act (S. 1521), a bill introduced on September 18, 2013. Murkowski proposes to prevent the federal government from granting contracts to third party certification seafood vendors, promoting a label based on criteria developed by a third party, and upholding standards that recommend third party seafood. This bill directly opposes third party seafood certifications. The National Marine Fisheries Service (NMFS) assisted MAFAC and NOAA in developing FishWatch, an agency dedicated to providing seafood consumers with information on federally managed fisheries (30). It competes with nongovernmental efforts by the Monterey Bay Aquarium and Blue Ocean Institute to “provide(s) easy-to-understand science-based facts to help consumers make smart sustainable seafood choices” (NMFS 2013). While still claiming neutrality, NMFS has taken a step towards federal certification and eco-labeling.

Fishermen in Sesimbra, Portugal. Photo source: Wikimedia Commons

In attempt to reconcile a national fishing industry and local fisherman with third party certifiers, NMFS has space to be the go-between and resolve conflict. In creating its own labeling and certification program, NMFS will serve as an advocate for fishermen in an economy that serves the consumer over seafood sustainability. The necessity and demand for a federally-managed certification program deals with issues such as market, fisheries, and communication. A reinforcing of existing structure coincides with the thought that third-party organizations and their certifications are methods of privatizing governance. MAFAC and NMFS tackle not only the definitions of sustainable fisheries but issues of control and who should have the authority to claim sustainability. In the future, fishery certification and eco-labeling could become the next wave of categorizing seafood, with “sustainable” sitting right alongside “organic” and the Organic Foods Protection Act (Stoll et al. 2014).

References

Bush S, Toonen H, Oosterveer P, Mol A. The ‘devils triangle’ of MSC certification: balancing credibility, accessibility and continuous improvement. Mar Policy 2013l 3:288-93

Christian C, et al. A review of formal objections to Marine Stewardship Council fisheries certifications. Biol Conserv 2013; 161: 10-7

Jackson J, et al. Historical overfishing and the recent collapse of coastal ecosystems. Science 2001; 293 (5530): 629-37

Marine Stewardship Council (MSC). McDonald’s first USa national restaurant chain to serve MSC certified sustainable seafood to all US locations. 2013b

National Marine Fisheries Service (NMFS). FishWatch. 2013

Rothschild B, Keiley E, Jiao Y. Failure to eliminate overfishing and attain optimum yield in the New England groundfish fishery. ICES J Mar Sci: J du Cons 2013:fst118

Sasser E, Prakash A, Cashore B, Auld G. Direct targeting as an NGO political strategy: examining private authority regimes in the forestry sector. Bus Polit 2006; 8(no. 3): 1-32

Stoll J, Johnson T. Under the banner of sustainability: The politics and prose of an emerging US federal seafood certification. Mar Pol 51 2015: 415-422

Towards more efficient longline fisheries: fish feeding behavior, bait characteristics and development.

January 26, 2015/0 Comments/in Conservation, Ocean News /by aanstett

By Sarah Hirth, RJD Intern

There has been a growing demand for bait resources seeing that standard bait types, such as squid, herring and mackerel are also used for human consumption. As a result, bait prices have increased, thus increasing the demand for an alternative bait, one that is not based on resources used for human consumption. This study highlights factors that need to be taken into consideration when looking for alternative bait, and explores attempts of alternative baits that have been made.

Løkkeborg at al. agree that an alternative bait should be “effective, species- and size-selective, practical for storage and baiting, and based on low-cost surplus products.” An alternative bait that would meet all of these characteristics would also make the procedure of longline fishing more environmentally friendly.

Although there have been several attempts to develop alternative baits, these have had limited success (e.g. Bjordal and Løkkeborg 1996; Januma et al. 2003; Polet al. 2008; Henriksen 2009). There have been two main methods, which have been used to create the alternative bait. These are natural resources, such as surplus products from the fishing industry and synthetic ingredients as attractants. Mentioned types of alternative bait are: Norbait, artificial bait invented by William E.S. Carr, bait bags, and arom bait.

When these baits were tested, they all resulted in some positive factors. However, they still had undesirable outcomes. For example Norbait, which is based on surplus products, where minced fish products are mixed with alginate (a gelling agent, used as the binder) and extruded into a fiber mesh tube, has resulted in species –selective effects. In fishing trials Norbait has resulted in increased catch rates of two to three hundred per cent for haddock, yet Norbait compared poorly to natural bait for cod. “Compared to natural bait, minced herring enclosed in a nylon bag resulted in a 58% higher catch rates for haddock, a non-significant catch increase for tusk and ling, and a considerably lower catch rate for cod.” Similar results were observed with the other types of alternative baits.

The efficiency of longline baits depends on several factors, which are important to take into consideration when finding alternative baits. Some factors include: bait size, texture, and taste. An alternative bait also needs to be based on an odor source, and attractants need to be released over a considerable period of time. Løkkeborg et al. state that “the knowledge of food search behavior in fish is the basis of bait development efforts.” The list of factors affecting feeding behavior in this review includes: temperature, feeding motivation and hunger state, diel, tidal and annual rhythms, light levels, seasonal change in photoperiod, and water currents.

Although there currently are no alternative baits used in longline fishing, Løkkeborg et al. hope that improved knowledge of how fish respond to baited gear will aid future research aimed at the development of alternative baits. As the demand for marine resources for human consumption continues to increase, costs for longline bait are also likely to keep increasing. “The development of alternative baits used on resources not used for human consumption may therefore prove to be critical to a viable longline fisheries.”

Løkkeborg, S., et al. (2014). “Towards more efficient longline fisheries: fish feeding behaviour, bait characteristics and development of alternative baits.” Reviews in Fish Biology and Fisheries 24(4): 985-1003.

“Near-future Ocean Acidification Will Require Single-Species Approach to Management”

January 23, 2015/0 Comments/in Conservation, Ocean News /by aanstett

By Stephen Cain, RJD Intern

It’s difficult to predict the effects of near-future ocean acidification (OA) across ecoregions and ocean habitat. The body of research has been conducted under a variability of circumstances and conditions. While evidence continues to mount for OA as a global mega trend, researchers like Christopher E. Cornwall and Tyler D. Eddy call for the need to contextualize OA within local coastal communities. It is there, after all, that the combined effects of pollution, resource extraction, and preservation interact within geographically distinct units. The results of multiple stressors, anthropogenic or otherwise, can alter an ecosystem’s structure and function. In their recent study, Cornwall and Eddy suggest that management regimes rely on current global predictions as well as modeling of single-species’ response to changes in ocean chemistry.

For their study, Cornwall et al. used the intertidal and subtidal habitats from the Wellington south coast, and the Taputeranga Marine Reserve off New Zealand. Both possess similar substrate and habitat, and fall within the larger Cook Strait Region. Wellington features extant commercial and recreational fisheries that primarily target Lobster (Jasus edwardsii), Abalone (Haliotis australis and Haliotis iris), as well as Blue Cod (Parapercis colias) and Butterfish (Odax pullus). According to cited work by Breen & Kim (2006), Cornwall et al. note at the time of study that Lobster abundance had been maintained at 20% of original unfished biomass. Taputeranga Marine Reserve (MR), by contrast, was established as a no-take zone at its outset in 2008.

Jasus edwardsii (http://commons.wikimedia.org/wiki/File:Jasus_edwardsii_02.JPG)

Building on a model developed by Eddy et al. (2014), Cornwall and Eddy describe the challenge of scaling down global predictions of OA to their study area. In the body of literature, the effects for net-calcification have been generated from a variety of “carbonate chemistry conditions.” The resulting baselines do not, on their own, serve as complete proxies that the research team could use to base their predictions on. They relied on calculating levels of “dissolved inorganic carbon and total alkalinity, pH on total scale, and partial pressure of CO2” in the survey area, and compared this to the predicted rise of CO2 concentrations between 2014 (380 ppm) and 2050 (550 ppm).

To measure the ecosystem dynamics they used Eco-modeling software EwE. They examined a fully factored set of scenarios comprised of four criteria: fished areas (Wellington), non-fished areas (MR), and the presence or absence of OA. In order to generate estimates for 2050, fishing mortality was held constant from 2008 biomass. The scenario for fished area with an absence of OA was used as the baseline of the study. To further delineate changes over time, four indicators of ecosystem interaction were synthesized:

Proportion of benthic biomass affected
Proportion of pelagic biomass affected
Impact by Trophic Level
Mean Trophic Level of community

After initial modeling, they noted that certain species showed dramatic changes in abundance across scenarios. Further sensitivity analyses, referred to as “blanket modifiers,” strengthened their assumptions about the changes in food web interaction and ecosystem function. One of the more noteworthy findings were the predictions of abundance for Lobster, a keystone species. Outside of the marine reserve Lobster numbers were maintained, albeit at a “fraction” of their original unfished biomass. In a scenario of MR + OA in 2050, however, Lobster abundance was reduced by 42%. This was due to heightened sensitivity to OA. As a result, researchers predicted there would be fewer predations on species at lower trophic levels, and subsequent shifts in the structure of the food web. In that same scenario, “Abalone, piscivorous fishes, and herbivorous fishes increased in biomass by 52%, 11%, and 13% respectively.”

These results may be counterintuitive because there is the expectation that protected areas better compensate for additional stressors than do areas under fishing exploitation. This is the case, and that was what the team correctly hypothesized. However, Cornwall et al. point out the nuances of near-future ocean acidification at a species-specific level. They maintain that the effects will be “subtle, species specific, and context dependent.” Apart from calcareous species, not all species stand to lose, and, in fact, some may flourish. Cornwall and Eddy suggest that these findings can be useful when comparing regions, and targeted catches of species, especially those that will face increased pressure from changes in ocean chemistry.