How will climate change affect the life cycles of fish?

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by Asta Mail, RJD Intern

In a coffee shop the other day, I overheard two teens discussing technology and how it affected their lives. “How did anyone ever grow up without cell phones?” they wondered aloud. “How did they know when and where to meet up?”

Hearing this, I began to consider the ways people navigate the world, and how differently we do so now than we did in the past. Today’s youth has quickly learned and adapted to a very different social climate than that the previous generation. Growing up in an age of rapid development, they are accustomed to regular advances in communication, travel, and social interaction. Young people encounter very different obstacles through the stages of their development than their parents once did.

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Fatal Attraction: Debris and Sea Turtles

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by Nick Perni, RJD Intern

 

For decades there has been a steady increase in the production of plastic materials. Due to negligent disposal techniques and the resiliency of the material, plastic accounts for 80% of all Marine debris in some areas. The large abundance of plastic in the world’s oceans and coastal areas has detrimental effects on marine organisms. Sea turtles in particular have been heavily affected; all six species have been recorded to ingest debris nearly 90% of which is made up of plastic. The two main ways that plastic debris affects turtles is by entanglement and ingestion. Entanglement can kill organisms by preventing it from escaping predators or drowning the animal. Ingestion can also be lethal; many animals that ingest plastics can suffer from a punctured or impacted digestive system and are also susceptible to chemicals leeching from the plastic.

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University of Miami scientists catch great white shark in Florida Keys

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5/14/13
David Shiffman, Abess Center for Ecosystem Science and Policy student

Yesterday, during the course of sampling for our ongoing shark population survey, the RJ Dunlap Marine Conservation Program (RJD)  team caught a great white shark estimated at 10-11 feet in length. The shark was caught east of Islamorada in the Florida Keys, in approximately 100 feet of water.

A great white shark caught in the Florida Keys on 5/13/13. Photo credit: Virginia Ansaldi, RJ Dunlap Marine Conservation Program intern

A great white shark caught in the Florida Keys on 5/13/13. Photo credit: Erik Mohker, a Coral Shores high school student

 

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Fish Aggregating Devices: Ecological Problems with a Common Fishing Technique

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by Tom Tascone, RJD Intern

If you’ve seen the television show “Wicked Tuna” on National Geographic, then you are certainly familiar with some of the techniques associated with long line fishing of these species.  While this is the method of choice for recreational fishermen, commercial fishermen seeking various species of tropical tuna have abandoned the traditional “rod-and-reel” technique for a far more effective tool.  Known as the Fish Aggregating Device (FAD), this tool relies on the natural behavior of tuna to congregate under floating objects on the surface of the ocean.  Most FADs are made from bamboo rafts in order to mimic natural logs and other marine debris that often drift out at sea, and large numbers have been deployed. Besides dramatically increasing the number of tuna caught in fisheries operations, how have the use of FADs modified the “floating object environment” in the ocean, and what effects can they have on marine ecosystems? A recent article published by Dr. Laurent Dagorn has attempted to answer these important questions.

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Anthropogenic Noise Pollution and Cetaceans

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Brittany Bartlett, RJD Intern

It is no secret that our oceans and the species within them face a wide range of anthropogenic, human induced threats. And, as a result, the health of the ocean is rapidly declining. Among these threats is that of pollution; plastics, oil, runoff, etc. One form of pollution that tends to be overlooked is noise pollution, specifically the use of Navy Sonar.

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Seismic airguns: A threat to our oceans

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by Zackery Good, RJD Intern

As the third anniversary of the Deepwater Horizon oil spill approaches on April 20th it is important to look at the lessons learned as well as the current state of offshore drilling.  The Deepwater Horizon spill released over four million barrels of oil into the Gulf of Mexico before finally being capped after 84 days (Camilli et al. 2010, Crone and Tolstoy 2010) .

Figure 1. NASA satellite image of oil slick from Deepwater Horizon spill May 24, 2010 (Wikimedia Commons)

Figure 1. NASA satellite image of oil slick from Deepwater Horizon spill May 24, 2010 (Wikimedia Commons)

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Cruise Ship Pollution

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by Dani Escontrela, RJD Intern

On a regular basis I am at Port Everglades which is one of the biggest cruise ships ports in the world and on any given day can house six or seven cruise ships, if not more. Every Saturday and Sunday the Oasis of the Seas and the Allure of the Seas are there, which are the biggest cruise ships in the world. These floating cities are extraordinary, everything needed to survive is on there and it functions just like any other city. They can even carry thousands of people at a time. I’ve been on cruise ships before and it feels like magic; everything is taken care off and at times it doesn’t feel like you’re out at sea. Cruise ships provide an important source of income through tourism not only to those working on the ships but to the ports of call that are visited (Cohen 2002); however, something we don’t think about the damage that cruise ships can cause. These ships can be a major source of waste and many times different cruise lines have been found guilty of illegally disposing of their waste. In fact some cruise lines like Regency Cruises, Celebrity Cruises, Princess Cruises, the Holland America line, and Royal Caribbean, among others, have been convicted in the past of illegally dumping oil, garbage, paint, plastic, ballast water and food waste into the waters of Alaska and the Caribbean (Cohen 2002). These acts have either been due to negligence, by accident or have been willful acts (Cohen 2002).

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Porpoises in Peril: Assessing Conservation Efforts for the Yangtze Finless Porpoise

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by Zackery Good, RJD Intern

Imagine you are a Yangtze finless porpoise, swimming through the Yangtze River in China (Figure 1).  As you go about your daily business of finding food, you must navigate your way through heavy boat traffic, fishing gear, and water construction projects. The water you swim in is likely polluted and filled with debris.  However, there are some relatively safe areas in which you can seek refuge from these dangers.  The usefulness of these safe areas is evaluated in Zhao et al.’s 2013 publication Distribution patterns of Yangtze finless porpoises in the Yangtze River: implications for reserve management.

Figure 1, a Yangtze finless porpoise. Image via WikiMedia comons

Figure 1, a Yangtze finless porpoise. Image via WikiMedia comons

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Whale Funeral: Underwater Decomposition of Large Carcasses

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by Emily Rose Nelson,
RJD Intern

Like any living thing, the lives of whales must come to an end at some point. Upon the death of these massive creatures some may strand and end up on shore, others may float and quickly be removed by other animals, and at least 50 percent will sink to the bottom of the seafloor. Whale carcasses reaching the depths of the ocean support high diversity by providing immense quantities of organic matter, a phenomenon known as a whale fall. The cold deep water acts as a refrigerator and slows decomposition significantly. Under these circumstances whales have the ability to live on after their death for over 50 years supporting entire communities in the deep sea.

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Who’s your daddy? A scientific perspective into the evolution of great white sharks

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by Becca Shelton, RJD Intern

There are few things I love more than sharks and a good debate. The white shark, or great white, (Carcharodon carcharias) is my favorite species of extant sharks and the megalodon shark (Carcharodon megalodon) is my favorite extinct species. It just so happens that both species are in the center of an interesting dispute. Who is the ancestor to the white shark? For a long time, I personally had no doubt it was the megalodon shark because of similar looking teeth and jaws. In reality, this is not an easy question to answer. One of the reasons is that the species of sharks that are theorized to be the “closest” ancestor are extinct. Since sharks possess a cartilaginous skeleton, there is almost never a fully preserved skeleton since cartilage does not preserve well, unlike animals with boney skeletons. However, shark teeth are covered in enamel which helps in preservation and fossilized shark teeth can be found all over the world. Most of the debates surrounding this white shark ancestry involve teeth, especially morphology and serration. The two major theories I will be discussing are the megalodon hypothesis (Carcharodon megalodon) and the hastalis hypothesis (Isurus hastalis).

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