Trawling on seamounts: effects on corals

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By Jennifer Dean,
Marine Conservation student

Have you ever wondered how your seafood is caught?  Many of the species commonly consumed by humans, such as cod, flounder, and shrimp, are caught by a method called bottom trawling (montereybayaquarium.org).  Bottom trawling is a large scale fishing method that has been used for many years, consisting of dragging a large net or nets along the seafloor to scoop up fish that live near the bottom.  Unfortunately, this method is not very ecosystem-friendly.  Most trawl nets include heavy wooden or metal frames to keep the nets open, and these frames drag along the bottom, creating troughs, re-suspending sediment, and damaging organisms.  Recently people have begun to realize just how devastating these impacts can be on seafloor habitats.  In fact, just this past September it was shown that bottom trawling severely alters the ocean floor through smoothing of the local topography (Puig et al. 2012).  One ocean habitat that has been heavily impacted by bottom trawling is that of seamounts.

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Satellite Tagging and Manta Ray Conservation

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By Kayleigh Michaelides
Marine conservation student

The Manta Ray:

The giant manta ray (Manta birostris) is the world’s largest ray species with a disc width of up to 7m from wing tip to wing tip (Graham et al. 2012). Despite their large size, mantas are harmless to humans. Manta rays have a broad distribution throughout the world’s tropical and temperate oceans, and little is known about the size of the global population (Marshall et al. 2011). Manta rays aggregate in large groups in areas off the coasts of Mexico, Mozambique, Hawaii, and the Maldives. It is thought they gather in these areas to breed and visit cleaning stations (Graham et al. 2012). Manta rays are long lived, late to mature, and produce 1 to 2 live pups every few years, making them vulnerable to fishing pressure and slow to recover from population threats or disturbances (Marshall et al. 2012). The rate of population decline in the past 75 years in parts of their range may be as high as 80%. Globally, it is suspected that manta rays are declining at an estimated 30%. This population decline has been attributed mainly to both targeted fishing and incidental (by-catch) mortality (Marshall et al. 2012). Currently, M. birostris is listed as “vulnerable” on the International Union for Conservation of Nature’s Red List.

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Dietary preferences of lionfish in the United States

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by Audra Burchfield,
Marine conservation student

Imagine being a reef fish around twenty years ago. You are swimming around when all of the sudden a new fish you have never seen before is on the reef. Over the next few years more of these strange fish are present and pretty soon they are common place. The reef has been invaded by an alien.

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Incidental captures of sea turtles in the driftnet and longline fisheries in northwestern Morocco

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By Ana Zangroniz, Marine Conservation Student

One important issue in marine conservation lies with the preservation of a healthy sea turtle population. Of the seven species (Leatherback, Green, Loggerhead, Hawksbill, Olive Ridley, Kemps Ridley, and Flatback), six are endangered or threatened. Besides the fact that these creatures are visually stunning, they play a crucial role in marine ecosystems, which can directly affect human beings and our livelihoods. For example, green sea turtles feed on seagrass. This grazing keeps seagrass beds healthy, helping maintain critical habitats for many life stages of scallops and mollusks that humans depend upon as a food source (Carroll et al. 2012, Nizinski 2007). Additionally, when female sea turtles come ashore to lay their eggs, beach ecosystems are enriched, as turtle eggs are a significant source of nutrients for plant life (Vander Zanden et al. 2012).

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Are Marine Protected Areas Effective?

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By Natalie Torkelson,
Marine conservation student

Living in South Florida, most people are familiar with the concept of Marine Protected Areas (MPAs). The Florida Keys National Marine Sanctuary is just one of these protected areas in Florida. Six percent of the sanctuary consists of fully protected zones. Along with the fully protected zones, 27 management areas were designated when the sanctuary was created, and the sanctuary also includes 20 existing management areas that have been designated by other agencies (National Marine Protected Areas of the United States). Biodiversity, or the amount of different species in an area, is often used as an indicator of what areas are important and should be protected (Chapin et al., 2000). However, there is much evidence that there are other factors that should be taken into account when making decisions about what areas should be conserved. Many ecosystems depend more on functional diversity to remain healthy and productive than on the number of different species that it has (Nystrom 2006). Functional diversity is the number of different biological functions or processes in an ecosystem, and this, as well as trophic levels can be used to compare the communities in different areas. Measuring each of these things can help determine what areas are important to conserve, but are marine protected areas really effective? One study in the Mediterranean set out to answer this question by comparing the species, trophic, and functional diversity of protected and non-protected areas. The hypothesis was that species, trophic, and functional diversity were higher in protected areas than in adjacent non-protected areas (Villamor and Mikel 2012).

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Possible Links Between Estuarine Pollution and Invertebrate Biodiversity

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by Monica Yasunaga,
Marine conservation student

Marine degradation from coastal pollution is difficult to measure without the appropriate frame of reference.  The parameters that must be considered include the physical, chemical, and biological interactions that are taking part in an area. To understand the extent to which human-induced development and activities affect marine ecosystems, biologists can look to the bottom of the food chain for the meat of the story.  Benthic invertebrates, namely those organisms inhabiting the seafloors, are vital to the rest of the food web.  Unlike the popular macro invertebrates of the sea (i.e. octopi, squids, and sea jellies) benthic invertebrates are significantly smaller in size– from microscopic to just a few centimeters long (Figure 1 below).  On the sea floor they inhabit the surface of rocks, vegetation, coral, and the tiny spaces between sedimentary deposits.  These animals support entire food webs, provide ecological services by overturning sediment via burrowing, and are an integral part of aquatic nutrient exchange (Gray et al. 1990).  Changes in benthic invertebrate biodiversity over time may be linked to marine pollution trends in coastal ecosystems.

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Ruling from the top-down: Sharks as Apex Predators and the Need for Better Management

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by Tom Tascone, RJD Intern

An apex predator is defined as a predator residing at the top of the food web in its ecosystem.  Life at the top has its benefits – reigning supreme in its environment, the apex predator feeds on lower levels in the food chain and has no natural predators of its own, allowing it to enjoy the freedom that comes with being the hunter, not the hunted.  Many examples of apex predators exist in both terrestrial and marine habitats, and if you were to ask anyone, despite their scientific expertise, to name a marine apex predator, you would certainly get some type of shark as your most common answer.

The influence of apex predators like sharks on marine ecosystems, however, has been little studied.  Marine food webs are incredibly large and complex, and encompass a wide variety of species. Additionally, many of these species act as both predator and prey and interact with multiple other species in both capacities, complicating research that much further.  However, as anthropogenic (human-induced) changes to marine ecosystems through activities like commercial fishing continue to deplete many fish populations, sometimes upwards of 90%, growing concern has spurred new research in this area (Baum and Worm 2009).  Focusing on the potential effects that anthropogenic change can have on the structure of marine food webs, this research has identified just how important sharks are in their role as apex predators.

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Jellyfish Blooms are the Result of Global Oscillations

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by Megan Piechowski, RJD Intern

A recently observed increase in the abundance of jellyfish populations has been suggested to be a symptom of deteriorating oceans. Other indicators include: ocean acidification, eutrophication, and declining fish stocks. However, this conclusion might have been reached prematurely as a thorough and formal analysis of the long-term fluctuation of global jellyfish populations did not exist. In Recurrent Jellyfish Blooms Are a Consequence of Global Oscillations, Condon et al gathered data sets containing the distribution of jellyfish populations from thirty-seven locations around the world between the years of 1790 to 2011 (picture 1).

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Coastal Habitat Modification and its Impact on Sharks

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by Fiona Graham, RJD Intern and Masters student

New canals are being built, waterways are undergoing modification, coastal urbanization is on the rise and mangrove, seagrass and other coastal vegetation cover is decreasing. Changes in coastal geomorphology alter sedimentation patterns and consequently the physical and biological structure of nearshore habitats is changing. Artificial habitats generally replace rocky reef substrate with smoother concrete structures and therefore differ from natural habitats in structural and surface complexity. These types of coastal habitat modifications are occurring on a global scale, and these changes can have lasting implications for the species that inhabit these areas. Some of these species include sharks, particularly those shark species that rely on coastal ecosystems for at least one stage of their life history.

One of these such species is the bull shark, Carcharhinus Leucus. Bull sharks are particularly vulnerable to coastal habitat modification due to their consistent use of estuarine and freshwater areas. They are one of the few shark species that are capable of tolerating freshwater for long periods of time, thereby resulting in increased encounters with humans. This overlap subjects them to increased anthropogenic impacts such as high fishing pressure and, of course, changes in the environments they inhabit.

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Reproduction in the deep sea

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by Megan Piechowski, RJD Intern

Have you ever wondered how small, sparsely populated fish find each other to mate in the deep, dark ocean? Due to the unusual light organ that is found dangling over the mouth of a certain deep-sea creature it is likely one of the most well-known and recognizable fish that dwells in the deep sea (Picture 1). These fish were discovered ninety years ago and have been studied extensively due to their use of an extremely unique and successful reproduction strategy. Over sixty years ago this discovery remained unfathomable to many. The first scientist to descend into the deep abyss, William Beebe, likely faced much disbelief about these unknown organisms:

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