A colleague, friend, and former roommate of mine took a post doc position over in Australia around this time last year, doing harmful algal research. He recently sent me this video:
It’s pretty wild. And to think, people here on the east coast are complaining because their streets weren’t plowed fast enough! Imagine these rapidly moving flood waters racing down your street? Absolutely nuts. It has claimed lives and caused considerable devastation. Obviously, due to the harsh weather we have been receiving here, we haven’t heard all that much about the flooding. You can read about some of it here, here, here, and here. My friend Tim even blogged about it. Google it too, theres plenty of info about it out there.
An interesting article I came across piqued my interest – the flooding has supposedly given bull sharks access to the town streets, and a couple have been spotted swimming around. Could you imagine? I mean wow! I find that both exciting and petrifying. On one hand, it just speaks to the incredible adaptive ability of bull sharks. On the other hand, they are often considered among the most aggressive sharks in the world, and you wouldn’t expect to see them wading through floodwaters in the middle of you town. Many of you are probably thinking how impossible that must be. But bull sharks are tolerant of fresher waters, and in some parts of the world, are found venturing up rivers! They are extremely tolerant of wide-ranging salinities via unique osmoregulation abilities. In fact, these sharks are often found in rivers, even in the US, like Alabama and the Potomac River. It is also thought that a bull shark is responsible for the Matawan creek attacks in 1916, an event originally attributed to a white shark and the inspiration for the movie Jaws.
Maybe Chuck over at Ya Like Dags or David over at Southern Fried Science might have some more insight into the reasons bull sharks are so freshwater tolerant. But I thought it was interesting and worthy of mention.
Edit- Shark biologist Lyndell Bade informed me that bull sharks can be found up the Mississippi all the way to St Louis and can live in Lake Nicaragua. These are quite amazing fish.
Well, more bipartisan cooperation this week, which after almost 2 full years of bickering is a bit refreshing. Especially when it comes to a fisheries related issue – shark finning. Yesterday, the bill went through the Senate, and this morning, passed through the House. Now all Big-O has to do is sign the thing into law. Although some measures of protecting sharks have been in place for some time, shark finning was popular since the fins fetch considerably more dollars than other shark meat. This practice involves catching sharks, cutting off their fins and throwing the finless fish back overboard. I guess this is in an attempt to maximize landings of valuable meat, as I assume catch quotas are on a poundage basis. Now, all sharks landed have to be kept whole. Additionally, other vessels cannot transport fins. Not knowing much about the shark fin trade, my guess is that most shark people will see this as good news. Of course, there is always exceptions, and a smooth dogfish fishery will be allowed to continue finning practices, but such is the cost of compromise in getting enough support for the bill to pass. Hopefully this is all a step in the right direction. WhySharksMatter over at Southern Fried Science blogged about it today, so check it out. Also, to learn more about shark finning, check out this post from Ya Like Dags from last month.
Well not quite. White sharks have been receiving a considerable amount of press this summer in the northeast (see here, here, here, and here). Apparently, there were so many sightings that the US Coast Guard issued a white shark advisory, warning people of the northeast that (shocker!) there are white sharks in the water. However, these sea creatures hardly pose a threat to Long Island bathers, Dr. Demian Chapman, shark biologist from the Institute for Ocean Conservation Science, School of Marine and Atmospheric Sciences, Stony Brook, assured the general audience at Southampton College last Friday night.
True, the northeast used to be a hot spot for white sharks. There were a great many sightings in the 50s and 60s, sighting of both juveniles, adults and even some pairs that were believed to be mating. While little is known about the white sharks around Long Island at this time period, Dr. Chapman said that some researchers believe this might have been a spawning and nursery ground. That being said, there is little data on white sharks from this time period other than sightings. White shark fishing then became quite common, and some of the largest white sharks ever caught were landing on Long Island, particularly out in Montauk, where Captain Frank Mundus was renowned for being a top shark fisherman.
What happened over the course of the past decades is that white shark populations have dwindled in the northeast. While there might be some debate as to the magnitude of the decline, I think most researchers will agree that it is significant. Dr. Chapman is looking to use genetic tools to get a grip on how small (or big) the white shark population might be. Using samples from around 50 sharks, the data thus far shows that northeast white sharks have a low genetic diversity, indicative of a species that has experiences a considerable decline, also known as a bottleneck. This could be potentially devastating to coastal ecosystems along the US, as these animals are apex predators in the coastal food web.
So maybe the white shark advisory shouldn’t have been alerting the public about their presence in the waters of New England, but perhaps, they should have been warning us about their disappearance.
That all being said, I am no shark biologist, and the above information was from my notes at the lecture. To learn more about sharks, you should check out some other websites, like the one about New England Sharks, and other blogs by people in the know, such as this entry at Ya Like Dags
(My best shark photo, sorry!) So I check out Underwater Times from time to time to see whats new in the underwater news world. So when I happened upon this article from the United Arab Emirates, it reminded me of a Science paper that came out a few years back that is near and dear to my heart. But first, the news article. Essentially, sharks are a major fishery in the Arabian Gulf. From 1985 to 2000, shark landings in the UAE ranged from 1350 to 1900 tons of sharks, and the UAE is a major exporter of shark fins to Asia. However, scientists and fishermen alike have started to notice that the loss of shark predators has impacted the ecology of the Arabian Gulf. This has lead to a study to be undertaken examining these impacts.
In the article, a sentence mentions how the loss of sharks on the Atlantic coasts has lead to a collapse in bay scallops. So you guessed right, this is where the 2007 Science paper which I find so particularly fascinating comes in. This paper, entitled “Cascading Effects of the Loss of Apex Predatory Sharks from a Coastal Ocean,” by the late Ransom Myers and others detailed a study whose base conclusion was that the loss of sharks due to overfishing cascaded down the food web and resulted in the loss of bay scallops in North Carolina. They examined fisheries data for trends in individual species of elasmobranchs, the family of fishes to which sharks belong, from 1970-2005 between Cape Cod, MA and Cape Canaveral, FL. They were able to demonstrate strong decreasing trends in the abundance of great sharks, which are the apex predators. Over the same 35 year period, the populations of smaller elasmobranchs, including smaller sharks, skates and rays, were shown to be increasing. Many of these species, and the cownose ray in particular, are known consumers of benthic prey, including a variety of shellfish. In North Carolina, cownose rays move into the estuaries to feed in the summer, and were capable of removing entire bay scallop populations before they could spawn, and decimating populations to a point that densities were so low, that successful fertilization could not take place. By 2004, the North Carolina scallop fishery was gone. These mesopredators are also likely to be impacting the recovery of other shellfish species through consumption. Thus, the loss of sharks, even through by-catch, is likely to have devastating ecosystem impacts, not just in North Carolina, but likely in many coastal areas. (For other reasons why sharks matter, check out this website, this cool blog called Ya Like Dags, and the ongoing series of shark posts over on Southern Fried Science).
Myers RA, Baum JK, Shepherd TD, Powers SP, & Peterson CH (2007). Cascading effects of the loss of apex predatory sharks from a coastal ocean. Science (New York, N.Y.), 315 (5820), 1846-50 PMID: 17395829
Another paper that came out of the Charles Peterson group (he was a co-author on the above Science paper) investigated restoration options for scallops in North Carolina. Obviously, cownose rays still prevent a major problem. One mode of restoration they examined was a way to protect adult scallops in a spawner sanctuary from predation by the rays. They were able to accomplish this via a fairly simple method of using PVC stakes into the sediment that reached out of the water at high tide, evenly spaced narrowly enough so that the rays could not fit inside. This method was capable of successfully maintaining dense populations of adult scallops during the period when the rays were in the estuary. Obviously, allowing populations of adults to survive to spawning is a major step in enhancing scallop populations.
Stephen R. Fegley,* Charles H. Peterson, Nathan R. Geraldi and David W. Gaskill (2009). Enhancing the Potential for Population Recovery: Restoration Options for Bay Scallop Populations, Argopecten irradians concentricus, in North Carolina Journal of Shellfish Research, 28 (3), 477-489 : 10.2983/035.028.0309
I am a marine biologist that is currently attending graduate school at the School of Marine and Atmospheric Sciences, Marine Sciences Research Center, of Stony Brook University, New York. I am very interested in marine ecology and have been focusing my studies on bay scallop interactions with their habitats. I plan to investigate various anthropogenic impacts on bay scallop populations for my PhD dissertation. This blog will highlight the details of my graduate research, from bay scallop-eelgrass interactions as previously mentioned, to alternative habitats for scallops, such as Codium, to trophic cascades, and more. Enjoy!
Artificial Seagrass
Is a useful experimental tool to mimic natural seagrass while controlling many factors, such as density, canopy height, leaf number, which are usually confounding in natural eelgrass meadows.
Scallops seem to love this stuff!
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