Transcript No Slide Title - Metcalf Institute for Marine & Environmental Reporting

The Changing Climate
and Ecology
in Narragansett Bay
Candace Oviatt
10/12/12
Objective
To examine some of the local
environmental
and ecological patterns in Rhode
Island
waters associated with the recent
warming.
NARRAGANSETT BAY
Rhode Island Region
Warm
Cool
Warm
Climate Trends in Rhode Island
Changes in the Narragansett Bay 1970s- 1990s
Positive North Atlantic Oscillation - Biological Events
(Winter water temperature increase of ~ +2.4 C in Narragansett Bay)
1) Winter flounder decrease perhaps due to predation by Crangon (sand shrimp) on the eggs.
2) American lobster and other decapods increase in Rhode Island waters.
3) The winter-spring bloom fails in warms years in Narragansett Bay.
4) Eelgrass beds after some recovery to the 1960s, again decline.
5) Change in jellyfish cycle of abundance: ctenophores become most abundant in early summer
in contrast to former early fall abundance and prey upon copepods and larval fish in the water
column.
6) Oysters re-populate Narragansett Bay in 1990s; southern oyster disease, Dermo, invades
Rhode Island waters.
7) Increase in more southern species, like the smallmouth flounder.
Winter flounder decrease perhaps due to predation by Crangon on the eggs and larvae.
Collie et al. 2008: Abundance changes at the Fox Island station.
Narragansett Bay Trawl Survey, total per decade
25000
20000
15000
Northern Searobin
Lobster
10000
5000
0
60 - 70
70 - 80
80 - 90
90 - 00
10.00
8.00
6.00
4.00
Percent of Total
Fox Island Trawl
14.00
Cancer Crbs
Searobin
12.00
2.00
0.00
2001
1999
1997
1995
1993
1991
1989
1987
1985
1983
1981
1979
1977
1975
1973
1971
1969
1967
1965
1963
1961
1959
The winter-spring bloom fails in warms years in Narragansett Bay.
From Nixon files
Eelgrass beds now confined to the lower Bay. Bradley and Raposa 2007.
Change in jellyfish cycle of abundance: ctenophores become
most abundant in early summer in contrast to former early fall abundance
and prey upon larval fish in the water column.
Sulliv an, BK D Van Keuren, M C lancy (In press) Tim ing and size of bloo ms of the
ctenopho re Mnemiopsis leidyi in r elation to temp eratur e i n N arragansett Bay, RI
Hyd robio logia
Figure 1. Mnemiopsis leidyi . Pho to by H . Wes Pratt.
Copepods
Copepods
Mnemiopsis
leidyi
Mnemiopsis
leidyi
Chl a
Chl a
Cold Winter
J
M
M
J
S
N
Warm Winter
J
M
M
J
S
N
Summary
1) Annual temperature has increased about 1oC, rainfall has increased about 25%, cloudy days
have increased about 20%, and wind speed has decreased by about 20% since the 1950s.
2) New ecological patterns associated with warming in Rhode Island waters include:
Decreased northern bottom fish; increased decapods, including lobster.
Failure of the winter-spring bloom.
Eelgrass decline.
Changes in Ctenophore jellyfish cycles.
Questions?