NARRAGANSETT The ocean off Rhode Island has warmed 3.5 degrees Fahrenheit since 1959, when the University of Rhode Island began conducting bottom trawls.

The trawls, which are conducted weekly throughout the year, involve dragging nets along the ocean floor and collecting fish and other sea life to determine what is living in Narragansett Bay.

Joe Langan, a Ph.D candidate at the Graduate School of Oceanography at the University of Rhode Island, told the audience at a June 22 seminar that the weekly trawls, one of the longest-running data-collection initiatives in the world, had also revealed dramatic changes in the populations of fish and crustaceans that live in the bay.

Langan and fellow Ph.D student Ali Johnson were presenting the first in the new Bay Informed discussion series. Sponsored by Rhode Island Sea Grant, the free talks, which encourage members of the public to ask questions, will take place once a month.

Me and a couple of other grad students here, we were the founders, Johnson said. We came up with the idea and we all came together and created this event.

Johnson said she hoped that people attending the talks would come away with a better understanding of the ocean research taking place at URI. The lectures also give students opportunities to hone their communication skills.

I hope people are going to come away with a broader knowledge of some of the basic research that we do here, she said.

Johnson, who is studying physical oceanography, focused her presentation on the science-based evidence of climate change and included a tutorial on how ocean currents circulate around the globe.

In order to understand how these processes are going to change, its really important that we first understand whats going on, she told the audience. We know very, very little about the ocean. We know basics compared to some of the other science thats out there. It is so important that we learn what these physical processes are in order for us to better predict how these processes are going to change with increasing sea-surface temperatures and increasing air temperatures.

Langan is working on a Ph.D in biological oceanography and a masters in statistics.

My research is in quantitative fisheries ecology, which is just a fancy way of saying I like to do math about fish, he said.

Langan described Rhode Island as being on an ecosystem knife edge between the cold waters of the Gulf of Maine to the North and to the South, the Mid-Atlantic Bight. Traditional fish-migration patterns involved southern species coming to Rhode Island in the summer and northern species moving here for a period during the winter. Those patterns, which scientists refer to as residence times, have changed in recent years, because warm-water species are staying longer and species that prefer colder water arrive in Rhode Island later and leave sooner.

This is summer flounder, Langan said, pointing to a graph illustrating fish populations. Their residence time has changed by about five months. This is a very aggressive predator thats also a bit of a bully on the sea floor. It pushes other species out of different habitats. A five-month difference of how long a species spends in Narragansett Bay is a tremendous difference in the ecosystem. Theyre going to be eating a lot more. Theyre going to be out-competing other species. This is a massive ecological difference.

Winter flounder, on the other hand, have all but disappeared from Rhode Island waters, with a population decline of 99 percent. This population crash is also attributed to warming seas. Langan explained that predatory sand shrimp are now active earlier in the season, devouring winter flounder larvae.

They would show up when winter flounder were too big to eat, and maybe hide and defend themselves, but spring warming happens faster, and now these shrimp show up when winter flounder are mostly still larvae, and they eat them all, Langan said.

Winter flounder also face competition from scup. The population of scup in the bay has exploded in recent years, leaving less for the flounder to eat.

These and other changes, Langan said, show how seemingly minor temperature differences can affect an entire ecosystem.

When we think about climate change and ecosystems, its all about an interconnected web, where you dont have to change much, Langan said. If you change a little bit of seasonality for one species, it can have a huge ripple effect.

cdrummond@thewesterlysun.com

@cynthiadrummon4

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Warmer ocean brings changes to R.I., wreaks havoc on state's ... - The Westerly Sun