SOUTHEASTERN US MARINE SOUTHEASTERN US MARINE ECOSYSTEMS AND ECOSYSTEMS AND
HYDROCARBON EXPLORATIONHYDROCARBON EXPLORATION
Steve W. Steve W. Ross Ross
SEUS Marine SEUS Marine EcosystemsEcosystems
• Large estuaries and numerous rivers• Long coastlines, inshore and offshore• Extremely high marine and estuarine biodiversity (> 1000 spp. of fishes < 200 m, more than anywhere else in US except FL)
Moderate climateTemperate latitudes (warm and cool temperate with
subtropical inputHabitat diversity high (shallow and deep)Gulf Stream (nutrient dynamics, temperature modulation, transport)
Manteo ProspectHatteras Middle Slope
(“The Point”)
Since the late 1980s to early 1990s, there has been substantial progress in understanding offshore ecology.Even so, the farther offshore we go, the less we know, and in some cases there are almost complete knowledge gaps.
500 m
1000 m
• Dynamic oceanography• Rugged terrain• High carbon deposition• High infaunal biomass• Unusual communities• High productivity and biological activity
Depths in meters
Muds and canyons north of Cape Hatteras
Hard grounds and carbonate sands south of Cape Hatteras
A virtual data desert beyond 2000 m, esp. for benthic ecology & biology
Gulf Stream dominates regional oceanography.
Influences:•Weather/climate•zoogeography•genetic connectivity•nutrient delivery to shelf via upwelling•Designated as EFH
Sargassso Sea
Spawning migration
Juvenile recruitmentEstuarine-dependent species:Atlantic croakerAtlantic menhadenGulf flounderSpotSilver perch
Spring
FallWinter
Summer
Juvenile recruitment
Spawning migrationAnadromous species:American shadBlueback herring Hickory shadStriped bassAtlantic sturgeon
Catadromous species: American eelSpawning migration
Juvenile recruitment
Reef-associated species:Snapper/grouper
Juvenile recruitment
Freshwater Estuaries Nearshore Offshore
Michel 2011
Great connectivity between river/estuarine and offshore systemsBut less connectivity with deeper (> 200 m) waters
Takes place generally inshore
of 200 m
Big issues facing these resources are
degraded habitat and overfishing (by
catch issues).
Demersal fishes
Cat
ch (
mil
lion
ton
nes
)
0
2000
4000
6000
8000
10000
12000Pelagic fishes
0
8000
16000
24000
32000
40000
48000
0
500
1000
Reef associated fishes and flatfishes
Year
19501955
19601965
19701975
19801985
19901995
20002005
0
1000
2000
3000
4000
5000
6000
Flatfishes
All fishes
19501955
19601965
19701975
19801985
19901995
20002005
0
15000
30000
45000
60000
75000
90000
105000
120000
135000
Regional commercial fish landings. The great majority of these are caught in shelf depths. There are few current fisheries deeper than 200 m (exceptions = wreckfish, offshore pelagics)
(Michele 2011, www.seaaroundus.org)
This example of detailed estuarine and nearshore habitat mapping is typical of many states. This level of detail or precision is very rare offshore. Ecological knowledge declines rapidly with increasing distance offshore.
after Deaton et al. 2010
South Atlantic BightMarine Assessment
Benthic Habitat Hardbottom
Anderson et al. (in review 2015)
Shelf (<200 m) Hardbottom•Dominant resources = snapper, grouper, porgy complex & other reef fishes•Invertebrate fauna very rich but poorly studied•Reefs support diverse subtropical communities•Designated as EFH•Overfishing & habitat degradation are issues. Do the 6 shelf edge MPAs offer sufficient protection?
Deep-sea (> 300m) Coral Habitats• Banks scattered, but common on SEUS slope (370-
800 m), also on rocks and in canyons
• Very rugged topography (30-100 m tall mounds)
• High species richness, high numbers of species new to science and new to region
• Provide shelter, feeding areas, and possibly spawning areas to many species
• Support commercial & potentially commercial spp.
• Influenced by Gulf Stream dynamics, large environmental variations
Environmental data (2 Dec 09 – 16 May 10) from lander deployed at deep coral mounds off Cape Lookout, NC (430 m).
Note Gulf Stream intrusions on bottom (Temp & other spikes).
Gulf of Mexico 425 m
Gulf Stream
Loop Current
More deep-sea heterogeneity than expected
Deep Reef & Canyon Study Areas (groupings based on fish communities)
Genetic discontinuity also displayed by L. pertusa deep corals: GOM differs from SEUS
South Atlantic Fishery Management Council created 4 deep coral HAPCs (23,000 sq. miles) that protect most deep coral habitat off the SEUS.
The largest protected area off the continental US.
Off Cape Hatteras
Pelagic to Mesopelagic Environment:•Important fisheries (billfishes, sharks, dolphin, mackerels, tunas)•Highly migratory species•Charismatic & endangered species (mammals, turtles, seabirds, whale sharks)•Mesopelagic may have greatest abundance & biomass of any marine habitat•Role of mesopelagic fauna in carbon movement probably far underestimated•Important conduit for larval movement•Surface to mid-depth is area of likely spill impacts (as in DWH)•Important nursery and feeding habitats (Sargassum)
At least 80 fish species use Sargassum(Casazza & Ross 2008)
NE FACING SLOPE TOP WEST FACING SLOPE
¯ ¯
Cape Fear coral mound 3-D view
Cape Fear Bank
Baltimore Canyon
Areas recently (2006- ) mapped with high
detail, high precision multibeam sonar
Mapped boxes are only 4.4% of the two
planning areas.
RESEARCH TO RESEARCH TO CONSIDERCONSIDER
• Severe lack of biological data > 200 m (benthic & mesopelagic)Severe lack of biological data > 200 m (benthic & mesopelagic)• Multibeam mapping of interest/target areasMultibeam mapping of interest/target areas
– Strong need for better habitat descriptionsStrong need for better habitat descriptions• Trophodynamic studies (most bang per $$)Trophodynamic studies (most bang per $$)
– Complete unfinished studies, add othersComplete unfinished studies, add others• Interaction of physical oceanography and biologyInteraction of physical oceanography and biology
– larval transport, genetic continuity, dispersal barriers or larval transport, genetic continuity, dispersal barriers or conduitsconduits
• Population structure & connectivity studiesPopulation structure & connectivity studies• Marine larvae dynamicsMarine larvae dynamics
– distributions, seasonality, movementsdistributions, seasonality, movements• Locate ocean spawning areas for important speciesLocate ocean spawning areas for important species
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