Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Climate change causing significant shift in composition of coastal fish communities

01.07.2008
Invertebrates and warm-water species increase, bottom feeders decrease

A detailed analysis of data from nearly 50 years of weekly fish-trawl surveys in Narragansett Bay and adjacent Rhode Island Sound has revealed a long-term shift in species composition, which scientists attribute primarily to the effects of global warming.

According to Jeremy Collie, professor of oceanography at the University of Rhode Island's Graduate School of Oceanography, the fish community has shifted progressively from vertebrate species (fish) to invertebrates (lobsters, crabs and squid) and from benthic or demersal species – those that feed on the bottom – to pelagic species that feed higher in the water column. In addition, smaller, warm-water species have increased while larger, cool-water species have declined.

"This is a pretty dramatic change, and it's a pattern that is being seen in other ecosystems, including offshore on Georges Bank and other continental shelf ecosystems, but we're in the relatively unique position of being able to document it. These patterns are likely being seen in estuaries around the world, but nowhere else has similar data," said Collie.

Results of the research by Collie and URI colleagues Anthony Wood and Perry Jeffries will be published in the July issue of the Canadian Journal of Fisheries and Aquatic Sciences.

The weekly trawl survey by URI scientists began in 1959 and continues to the present, making it one of the longest data sets of fish species composition available. The survey has recorded 130 species, though the analysis focused only on the top 25 species, which accounted for 96 percent of the total number of animals collected.

Collie said that while most of the changes occurred slowly, an abrupt change appeared to take place in 1980 and 1981 when benthic species like winter flounder and silver hake declined and pelagic species including butterfish and bluefish increased.

"We think there has been a shift in the food web resulting in more of the productivity being consumed in the water column," Collie explained. "Phytoplankton are increasingly being grazed by zooplankton, which are then eaten by planktivorous fish, rather than the phytoplankton sinking to the bottom and being consumed by bottom fish. It's a rerouting of that production from the bottom to the top."

Collie noted that the increase in the numbers of lobsters and crabs is a result of their taking advantage of the benthic habitat abandoned by the bottom-feeding fish species.

Overall, the survey analysis found huge changes in the abundance of some species. Butterfish and bluefish, for instance, have increased in abundance by a factor of about 100 times while cunner has decreased by almost 1,000 times.

The analysis also found that while the total number of fish caught in each trawl increased over time, peaking in the 1990s, the size of those fish decreased.

"While we're catching more fish now, we're also catching smaller fish," said Collie, "and that corresponds with how the preferred temperatures of the fish here have changed. The fish community now is dominated by warm-water adapted species compared with what we started with, and fish that live in warmer water are smaller."

Collie added that fishing may also be a factor in the decline in fish size, since fishing removes the largest individuals from a population while leaving the smaller ones. However, he believes that climate is "the dominant signal." Sea surface temperature in the area of the trawls has increased by 2 degrees Centigrade since 1959, and the preferred temperature of the fish caught in the trawls has also increased by 2 degrees C.

"That seems to be direct evidence of global warming," he said. "It's hard to explain any other way."

The shift in species composition also correlates with the winter North Atlantic Oscillation index and with chlorophyll concentrations, which declined by 50 percent, both of which are related to warmer sea temperatures.

What do these changes mean for the future of Narragansett Bay?

"Our overall prediction is that Narragansett Bay is soon going to resemble estuaries to the south of us – Delaware Bay, Chesapeake Bay – so we'll experience what they are experiencing now," Collie said. "It will continue to get warmer and attract more southern species, such as blue crabs. Species that couldn't complete their life cycle here before may be able to do that now."

Todd McLeish | EurekAlert!
Further information:
http://www.uri.edu

More articles from Ecology, The Environment and Conservation:

nachricht Air pollution leads to cardiovascular diseases
21.08.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz

nachricht Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Air pollution leads to cardiovascular diseases

21.08.2018 | Ecology, The Environment and Conservation

Researchers target protein that protects bacteria's DNA 'recipes'

21.08.2018 | Life Sciences

A paper battery powered by bacteria

21.08.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>