Deep Sea Research Part I: Oceanographic Research Papers
Stable C and N isotopic composition of cold-water corals from the Newfoundland and Labrador continental slope: Examination of trophic, depth and spatial effects
Introduction
There has been increasing interest in cold-water coral ecosystems over the past decade. Cold-water corals may live for decades to hundreds or even thousands of years (Druffel et al., 1995; Roark et al., 2006; Sherwood et al., 2006) and create structurally complex habitat for invertebrates and fish (Henry and Roberts, 2007; Husebø et al., 2002; Krieger and Wing, 2002; Costello et al., 2005; Edinger et al., 2007). Despite the great deal of recent interest in cold-water corals, relatively little is known about their trophic ecology (Roberts et al., 2006).
Previous research on the trophic ecology of cold-water corals has focused mainly on the scleractinian Lophelia pertusa reefs of the northeast Atlantic. Aquarium and field observations show that L. pertusa may capture live zooplankton up to 2 cm in length (Mortensen et al., 2001; Freiwald et al., 2002). Fatty acid and stable nitrogen isotope signatures suggest cold-water scleractinia may also feed on detrital particulate organic matter (POM; Duineveld et al., 2004, Duineveld et al., 2007; Kiriakoulakis et al., 2005). Suspension feeding cnidarians at the Porcupine Abyssal Plain occupy a wide trophic niche, feeding on resuspended material and swimmers to compensate for seasonal shortages in fresh phytodetritus (Iken et al., 2001). Shallower-water octocorals consume a wide range of prey items, from bacteria to zooplankton and detrital POM in proportion to availability (Fabricius et al., 1995; Ribes et al., 1999; Coma et al., 2001; Orejas et al., 2003; Tsounis et al., 2006).
Here, we use stable isotopes to examine the trophic ecology of cold-water ‘corals’ (Alcyonacea, Pennatulacea, Antipatharia, Scleractinia) collected off Newfoundland and Labrador, in the northwest Atlantic Ocean (Gass and Willison, 2005; Mortensen and Buhl-Mortensen, 2005a; Wareham and Edinger, 2007). We present new data on tissue carbon (δ13C) and nitrogen (δ15N) stable isotopic composition of 11 species collected over a depth range of 50–1400 m. The δ13C and δ15N values of organisms are used to interpret food sources and trophic levels, respectively (Fry, 1988; Hobson et al., 1995; Vander-Zanden and Rasmussen, 2001). This is particularly useful when traditional methods of diet analysis, such as gut contents or incubations (Ribes et al., 1999), are impracticable.
A second objective of this study is to explore geographic patterns in δ13C and δ15N of coral tissues. Isotopic composition of primary consumers provides time-integrated data on processes operating near the base of the food web, such as eutrophication (Heikoop et al., 2000; Ward-Paige et al., 2005; Vander-Zanden et al., 2005) and nutrient dynamics across oceanographic gradients (Dunton et al., 1989; Schell et al., 1998; Sherwood et al., 2005a). A previous study from Newfoundland and Labrador reported higher δ15N in fish and invertebrates inhabiting the inner reaches of the continental shelf than in fish and invertebrates living near the shelf break (Sherwood and Rose, 2005). Here, we assess the strength of similar isotopic gradients along the main axis of the outer Labrador Current, from its origin near the Hudson Strait to the southern Grand Banks.
Section snippets
Sampling
Since 2003, coral specimens caught as trawl by-catch during stock assessment surveys and fisheries operations have been collected and stored at the Northwest Atlantic Fisheries Center in St. John's, Newfoundland (Wareham and Edinger, 2007). The dataset consisted of 169 coral tissue samples, representing 11 species, three regions and a depth range of 47–1433 m (Table 1). The regions represented were Hudson Strait, Labrador Slope, and southern Grand Banks (Fig. 1). The Hudson Strait and Labrador
Results
Within the pooled dataset, the effect of species was highly significant on δ13C (one-way ANOVA; F10,142=10.46, p<0.001), δ13C′ (F10,138=20.18, p<0.001) and δ15N (F10,154=16.81, p<0.001). Fig. 2 shows the distribution of coral species in δ15N vs. δ13C (uncorrected for lipid effects) space compared with previously published values for other components of the Newfoundland and Labrador marine foodweb. As a proxy for resuspended POM, we used sedimentary organic matter (SOM) data from the Labrador
Inter-specific variation in stable isotopic composition
Stable isotope values of δ13C and δ15N varied significantly among species, but showed weak and inconsistent patterns of variation in relation to depth or latitude. We hypothesise that differences in feeding habits account for the strong inter-specific variation, based on the wide range of habitats and colony morphologies, and the need to reduce inter-specific competition in food-limited, deep-sea environments (Iken et al., 2001). The distribution of data in Fig. 2, Fig. 3 provide a convenient
Acknowledgements
We gratefully acknowledge the fisheries observers and the officers and crews of the Canadian Coast Guard Ships Teleost and Wilfred Templeman for providing samples. We also thank Kent Gilkinson for logistical support, Alison Pye for assisting with stable isotope analysis, Graham Sherwood for sharing isotope data on Newfoundland and Labrador fish and invertebrates and for valuable discussions. The manuscript was improved by comments from two anonymous reviewers. This work was supported by the
References (75)
- et al.
Patterns of seasonal dynamics of remotely sensed chlorophyll and physical environment in the Newfoundland region
Remote Sensing of the Environment
(2001) Variations in nitrogen isotopic composition between sinking and suspended particles: implications for nitrogen cycling and particle transformation in the open ocean
Deep-Sea Research
(1988)- et al.
Temporal and regional variability in sources and cycling of DOC and POC in the northwest Atlantic continental shelf and slope
Deep-Sea Research II
(2002) - et al.
Gerardia: bristlecone pine of the deep-sea?
Geochimica et Cosmochimica Acta
(1995) Stable carbon isotope ratios of plankton carbon and sinking matter from the Atlantic sector of the Southern Ocean
Marine Chemistry
(1991)- et al.
Nitrogen-15 signals of anthropogenic nutrient loading in reef corals
Marine Pollution Bulletin
(2000) - et al.
Biodiversity and ecological composition of macrobenthos on cold-water coral mounds and adjacent off-mound habitat in the bathyal Porcupine Seabight, NE Atlantic
Deep-Sea Research I
(2007) - et al.
Food web structure of the benthic community at the Porcupine Abyssal Plain (NE Atlantic): a stable isotope analysis
Progress in Oceanography
(2001) - et al.
Organic biogeochemistry of the Darwin Mounds, a deep-water coral ecosystem, of the NE Atlantic
Deep-Sea Research I
(2004) - et al.
Kinetic fractionation of stable nitrogen isotopes during amino-acid transamination
Geochimica et Cosmochimica Acta
(1986)
Depth-dependence in stable isotopic ratio δ15N of benthic POM consumers: the role of particle dynamics and organism trophic guild
Deep-Sea Research I
Burial rates of organic matter along the eastern Canadian margin and stable isotope constraints on its origin and diagenetic evolution
Marine Geology
Seasonal variation in the stable carbon and nitrogen isotope biogeochemistry of a coastal cold ocean environment
Geochimica et Cosmochimica Acta
Geographical variation of the water column distribution of suspended particulate organic nitrogen and its 15N natural abundance in the Pacific and its marginal seas
Deep-Sea Research
Stable isotope analysis of some representative fish and invertebrates of the Newfoundland and Labrador continental shelf food web
Estuarine Coastal and Shelf Science
Late Holocene radiocarbon and aspartic acid racemization dating of deep-sea octocorals
Geochimica et Cosmochimica Acta
Food supply mechanisms for cold-water corals along a continental shelf edge
Journal of Marine Systems
Spatial and temporal variability of particulate matter in the benthic boundary layer at the NW European Continental Margin (Goban Spur)
Progress in Oceanography
Carbon and nitrogen isotopic composition of sedimenting particulate material at Station Papa in the subarctic northeast Pacific
Deep-Sea Research II
Field observations of Flabellum spp. and laboratory study of the behavior and respiration of Flabellum alabastrum
Bulletin of Marine Science
Feeding and prey capture cycles in the aposymbiotic gorgonian Paramuricea clavata
Marine Ecology Progress Series
The ultimate opportunists: consumers of seston
Marine Ecology Progress Series
Role of cold-water Lophelia pertusa coral reefs as fish habitat in the NE Atlantic
The effects of flow on feeding of three gorgonians from southern Taiwan
Journal of Experimental Marine Biology and Ecology
Mechanism of carbon isotope fractionation associated with lipid synthesis
Science
Particle flux and food supply to a seamount cold-water coral community (Galicia Bank, NW Spain)
Marine Ecology Progress Series
Trophic structure of a cold-water coral mound community (Rockall Bank, NE Atlantic) in relation to the near-bottom particle supply and current regime
Bulletin of Marine Science
Trophic relationships and isotopic gradients among arctic and subarctic marine fauna
Marine Ecology Progress Series
Patterns of groundfish diversity and abundance in relation to deep-sea coral distributions in Newfoundland and Labrador waters
Bulletin of Marine Science
Flow-dependent herbivory and growth in zooxanthellae-free soft corals
Limnology and Oceanography
The Sula Reef Complex, Norwegian Shelf
Facies
Food-web structure on Georges Bank from stable C, N, and S isotopic compositions
Limnology and Oceanography
An assessment of the distribution of deep-sea corals in Atlantic Canada by using both scientific and local forms of knowledge
Are Antarctic suspension-feeding communities different from those elsewhere in the world?
Polar Biology
Sources of carbon to deep-sea corals
Radiocarbon
Main lipid classes in some species of deep-sea corals in the Newfoundland and Labrador region (Northwest Atlantic Ocean)
Coral Reefs
Potential climate signals from the deep-sea gorgonian coral Primnoa resedaeformis
Hydrobiologia
Cited by (65)
Consumer isoscapes reveal heterogeneous food webs in deep-sea submarine canyons and adjacent slopes
2024, Progress in OceanographyECOfast – An integrative ecological evaluation index for an ecosystem-based assessment of shallow rocky reefs
2023, Journal of Environmental ManagementReinterpreting radiocarbon records in bamboo corals – New insights from the tropical North Atlantic
2023, Geochimica et Cosmochimica ActaCommensalism, antagonism or mutualism? Effects of epibiosis on the trophic relationships of mussels and epibiotic barnacles
2021, Journal of Experimental Marine Biology and EcologyCitation Excerpt :In fact, B-Epibiotic barnacles were notably smaller (max 5 mm) than the B-Free individuals (max 10 mm), suggesting that they might feed on different size particles. Indeed, the size of an individual can determine the size of particles ingested (Sherwood et al., 2008), with small organisms such as epibiotic barnacles being able to acquired smaller food particles in comparison to bigger free-living barnacles or mussels. These two characteristics (body size and filtration mechanism) could influence the type and the size of the particles ingested and generate the observed FA differences between barnacle states, as well as between the two species (barnacle vs. mussel).
Stable isotopes (δ<sup>13</sup>C and δ<sup>15</sup>N) in black coral as new proxies for environmental record
2021, Marine Pollution BulletinProteinaceous corals as proxy archives of paleo-environmental change
2020, Earth-Science Reviews