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University of MarylandCENTER FOR ENVIRONMENTAL SCIENCECHESAPEAKE BIOLOGICAL LABORATORY
COMIDA: Trophic patterns of lipids in the Chukchi shelf benthos
University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory, Solomons, Maryland 20688 ([email protected])
Karen A. Taylor and H. Rodger Harvey
INTRODUCTION
ABSTRACT RESULTS and DISCUSSION
STUDY AREA
SUMMARY Bibliography
Acknowledgements
A suite of lipid biomarkers (sterols, glycerol ethers, fatty acids, alcohols) were examined in the foot muscle tissue of nothern Neptune whelks (Neptunea heros) and body tissue of their primary prey, the northern clam (Astarte borealis), as well as surface sediment and particulate organic matter (POM) to investigate trophic patterns and potential carbon sources and cycling on the Chukchi Sea shelf. While fatty acids were the dominant lipid class found in both animal tissues and environmental samples, a broad diversity of lipid signatures were present with Astarte showing the highest total concentration. Among all samples algal-specific lipids were found in significant concentrations and suggest the incorporation of primary production in Neptunea either directly through detrital feeding or via trophic transfer through their prey. Other lipid signatures representing multiple potential sources that include both algae and invertebrates. The abundance of these biomarkers found in both animal tissues and environmental samples may reflect assimilation or multiple trophic levels of consumption by Neptunea.
The Chukchi Offshore Monitoring in Drilling Area (COMIDA) Program integrates both biological and chemical disciplines to provide a comprehensive baseline assessment of the Chukchi shelf and benthos prior to potential oil and gas development. Efforts to characterize the biota, water column properties and sediment chemical composition began in the summer of 2009 and have continued through the summer of 2010. An important goal is to expand beyond simple concentration information to examine trophic links using lipid biomarkers in the foot muscle of northern whelks (Neptunea) and body tissue of their primary prey, northern clams (Astarte) as well as surface sediment and POM. Molecular organic markers are well established proxies for tracing both the sources and processing of organic matter in the environment, but have limitations due to source specificity [1]. Phytoplankton produce a diagnostic suite of lipid signatures that include algal sterols and polyunsaturated fatty acids or PUFAs, but others represent multiple potential sources and thus provide no further discrimination of their organic origin [2,3]. While whelks are both carnivores and detritivores, clams are filter feeders and thus we found it important to investigate lipid biomarkers in the invertebrates as well as the POM and surface sediment.
% Phytol as an algal tracer
0
Neptunea
93
Astarte
15
POM (35m)
51
0-1cm Sediment
Fig. 1. Map of the Chukchi Sea showing COMIDA sampling sites and locations of samples analyzed and described here.
Fig. 7.Astarte and Neptunea collected during COMIDA.
This project was supported by the Bureau of Ocean Energy Management, Regulation and Enforcement. We thank the captains and crews of the R/V Alpha Helix and R/V Moana Wave for sampling and technical support. COMIDA scientists are thanked for assistance with sample collection and identification.
[1] P. A. Meyers. 1997. Org Geochem 27: 213-250.[2] D. M. Orcutt, G. W. Patterson. 1975. Comp Biochem and Physiol 50B: 579-583.[3] J. K. Volkman. 1986. Org Geochem 9: 83-99.[4] A. Mannino, H. R. Harvey. 1999. Geochim Cosmochim Acta 63: 2219-2235.
Neptunea
10 cm
Astarte
4 cm
!
!
!
!
Barrow
Atqasuk
Point Lay
Wainwright
0 5025Nautical Miles
COMIDA
0
-220
170o0'0''W
72o0'0''N
71o0'0''N
70o0'0''N
69o0'0''N
160o0'0''W165o0'0''W
Bathymetry(m below MSL)
09
8
7
6
5
4
3
2
1105
106
107
1013
1014
1015
1016
8
70 29
1
43
6
32
22
1
0 4
2
6
2
32 30
89
9 7
65
43
21
11
1 1
11
11
2
2
5 3
2
3
5
3 4
22
2
4 4
4
7
1
3
4
3
4
4
7
5
8
3
4
3
Collection site of Astare, Neptunea and sediment described here Collection site of POM described here
All COMIDA sampling sites
METHODOLOGY
Fig. 2. Schematic of analytical method [4]
Microwave Assisted Extraction
(80oC, 30mins)
Alkaline Hydrolysis
Fatty Acids
Gas chromatography (GC)/GC-mass spectrometry
Total Lipid Extract
Samples were spiked with internal standards (5a-cholestane & C19:0n
fatty acid) for quantification.
Astarte bodiesNeptunea foot muscle
Surface sedimentPOM
+ Derivatization
AlcoholsSterols
Lipid class: Sterols
0 .05 .10 .15
24-nor-cholesta-5,22-dien-3b-ol27-nor-24-cholesta-5,22-dien-3b-ol
Cholesta-5,22-dien-3b-olCholesterol
24-methylcholesta-5,22-dien-3b-ol24-methylcholesta-5,24(28)-dien-3b-ol
24-methylcholest-5-en-3b-ol24-ethylcholest-5-en-3b-ol
24-ethylcholesta-5,24(28)-dien-3b-ol
24-methylcholesta-5,22-dien-3b-ol24-methylcholesta-5,24(28)-dien-3b-ol
24-methylcholest-5-en-3b-ol24-ethylcholest-5-en-3b-ol
24-ethylcholesta-5,24(28)-dien-3b-ol
mg/g Neptunea muscle
AstarteNeptunea
mg/g OCPOM (35m)0-1cm Sediment 0 200 400 600 800 1000 1200
24-nor-cholesta-5,22-dien-3b-ol27-nor-24-cholesta-5,22-dien-3b-ol
Cholesta-5,22-dien-3b-olCholesterol
mg/g Sediment70 1 2 3 4 5 6
64 50 1 2 3
mg/g Astarte body mass
Fig. 3. Concentration of sterols in invertebrate and environmental samples.
Fig. 4. Relative abundance of phytol to the total alcohols in invertebrate and environmental samples.
Results and ImplicationsCholesterol is the most abundant sterol in Astarte, Neptunea and surface sediment samples.
Significant concentrations of algal-derived sterols found in all Neptunea demonstrates that it incorporates algal carbon directly through detrital feeding or perhaps indirectly through carnivory of their filter-feeding prey, Astarte.
Multiple sources
1.81.6
Algal derived sources
20001400 1600 1800
Multiple sources
Algal derived sources
Lipid class: Fatty Acids
Algal derived sources Bacterial sourcesMultiple sources
0
100
200
300
400
1200
C14
C15
C16 P
UFA
C16
C17
C18 P
UFA
C18
C20 P
UFA
C20
C21 P
UFA
C21
C22 P
UFA
C22
C23-28
mg/
g m
uscl
e ti
ssue
Neptunea
Polyunsaturated
Monounsat.
Sat./ Branched
0
25
50
75
100
300
C14
C15
C16 P
UFA
C16
C17
C18 P
UFA
C18
C20 P
UFA
C20
C21 P
UFA
C21
C22 P
UFA
C22:2
C23-28
mg/
g se
dim
ent
0-1cm SedimentMonounsat.Sat./
Branched
Polyunsaturated
C14
C15
C16 P
UFA
C16
C17
C18 P
UFA
C18
C20 P
UFA
C20
C21 P
UFA
C21
C22 P
UFA
C22
C23-28
0
2
4
6
8
10
12
mg/
g O
C
POM
C14
C15
C16 P
UFA
C16
C17
C18 P
UFA
C18
C20 P
UFA
C20
C21 P
UFA
C21
C22 P
UFA
C22
C23-28
0
5
10
15
20
25
30
35
mg/
g bo
dy m
ass
Astarte
Polyunsaturated
Monounsat.
Sat./ Branched
Monounsat.
Polyunsaturated
Sat./ Branched
A diversity of fatty acids are shared among all animal & environmental samples.
Algal-specific lipid markers are present in substantial amounts in Neptunea, suggesting the incorporation of primary production either directly through detrital feeding or via trophic transfer through their prey.
Linkages of benthic feeders to organic contaminants are shown on the accompanying poster.
Lipid analysis reveals significant inputs of algal-derived organic matter to surface sediment and suggests that a fraction of bloom material reaches the benthos and is not recycled in the water column.
Lipid profiles of Astarte body mass show substantial amounts algal-specific signatures and reflect their consumption through filter-feeding.
Algal-derived fatty acids are abundant in Astarte and reflect filter-feeding of the water column after the spring bloom.
The dominance of PUFAs and abundance of saturated, branched and monounsaturated fatty acids in Neptunea reflect the consumption of primary producers as well as higher trophic levels.
Fig. 6. Concentration and relative abundance of fatty acids in invertebrate and environmental samples.
Results and Implications
Results and Implications
0
10
20
30
125
150
mg/
g tis
sue
Astarte
mg/
g tis
sue
Neptunea0
1
2
3
4
5
6
mg/
g se
dim
ent
0-1cm Sediment0
.02
.04
.06
.08
.05
.6
.7
mg/
g OC
POM (35m)0
10
20
30
40
50
60
Glycerol ethers Sterols Alcohols Fatty acids TOTAL LIPIDS
Among all samples fatty acids are the most abundant lipid class.
Fig. 5. Concentration of total lipid classes in animal and environmental samples
Results and ImplicationsAstarte show the highest concentration of total lipids.
Phytol accounts for over half of the alcohols found in surface sediment and reflects large algal inputs to the benthos as samples were collected after the spring bloom.
While phytol is only 15% of the total alcohols in POM, its abundance in Astarte suggest filter-feeding and storage of phytol in the gut.
