Bioaccumulation of Toxins in Shellfish and the Consequences for Human Health


By James Keegan, RJD Intern Toxic shellfish and toxic seafood in general are not modern phenomena. Human practices and records indicate that shellfish poisoning has been around for hundreds if not thousands of years. Many believe that diet restrictions dictated by the Bible demonstrate a wariness of shellfish poisoning. Moreover, Native Americans would keep watch for the flickering of ocean waves, an indication of dinoflagellate abundance, in order to know when to stop eating shellfish (Williams et al. 1999). Dinoflagellates are tiny marine organisms ultimately responsible for shellfish toxicity as well as the infamous red tides. More recently, the first … Continue reading

Modeling for Management: Predicting Ideal Conditions for Seagrass Habitat


By Emily Rose Nelson, RJD Intern Seagrasses are an essential part of the marine ecosystem. They provide food, habitat, and safe nursery areas to a wide range of species. Seagrasses help to stabilize the sea floor during intense currents and storms, filter nutrients coming from land-based runoff, increase water clarity by trapping sediments, generate oxygen, and store excess carbon. Unfortunately, seagrass area is in significant decline around the world largely due to cumulative impacts of human activities such as coastal development, increasing pollution, and reckless boating. It is of utter importance that conservation and restoration efforts are put into place … Continue reading

Competitive Interactions Between South American Sea Lions and Fishermen in Southern Brazil

Study area showing two fishing harbors (Imbé and Passo de Torres) in Southern Brazil. The gray circles represent fishing operations based out of Imbé and the gray triangles represent fishing operations based out of Passo de Torres. (Machado et al. 2015)

By James Keegan, RJD Intern Often, humans and top predatory carnivores compete for the same resources, even in the marine environment. This conflict occurs where fishing operations of humans and feeding areas of the predators overlap. In South America, fishermen complain of adverse competition from South American sea lions, which interact with all types of fishing gear. South American sea lions can interact with fishing effort either directly or indirectly. They can damage the fish captured by nets or the nets themselves, or they can decrease the relative abundance of local fish, decreasing the fishermen’s yield. Conversely, this competition can … Continue reading

Masked, diluted and drowned out: how global seafood trade weakens signals from marine ecosystems


By Jake Jerome, RJD Graduate Student It has been shown that global seafood trade inherently drives seafood production, negatively impacting marine ecosystems worldwide. While it is well known that these ecosystems are deteriorating, most research has been focused on global stock assessments, catch trends, or fisheries dynamics, with little attention given to researching the ways in which global trends are linked to consumers through trade. Fish prices can potentially be used as a feedback signal to consumers about the state of fisheries and marine ecosystems, but this method faces several issues. Crona et al 2015 dive deeper into the usefulness … Continue reading

Shark Tagging With Steve Brodie Charter

Dr. Neil Hammerschlag explaining RJD’s shark workup procedure

By Alison Enchelmaier, RJD Intern Friday morning couldn’t come fast enough. It felt like forever since I had been on a tagging trip and I was chomping at the bit to get started. The crew arrived an hour early to load gear and everyone seemed to be in a genial mood as we hauled drumlines and bait. Today our new intern, Julia Whidden, was joining us for her first trip! Just as we were loading up, we were joined by our group of UM citizen scientists. We headed out to Stiltsville, a series of stilt houses that reside offshore in … Continue reading

Shark Tagging with Riviera High


By Rachel Skubel, RJD Intern Last Sunday we had a fin-tastic trip with Riviera High, wherein we were fortunate enough to come across three unique species of sharks just a couple miles off of South Miami Beach – including a breathtaking 4-meter great hammerhead. This was our first secondary-school trip of fall 2015, and we were excited to get the students involved! When we set off in the morning, conditions were perfect for fishing offshore in deeper waters. The water was relatively calm, and the current not too strong. This meant we were able to head ‘offshore’ into deeper waters … Continue reading