Assessment of Trophic Positions for the Seabirds of South Florida using 13C and 15N Stable Iotopes
Background/Question/Methods Seabirds outside the Northeast Pacific and Northeast Atlantic regions are poorly understood from a trophic perspective. To elucidate trophic level relationships, we examined the concentration of ∂13C and ∂15N in the blood, breast muscle, and feathers (proximal and distal...
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ftnsoutheastern:oai:nsuworks.nova.edu:occ_facpresentations-1652 2023-05-15T17:41:47+02:00 Assessment of Trophic Positions for the Seabirds of South Florida using 13C and 15N Stable Iotopes Young, Michael Hirons, Amy Martinez, Zara Kerstetter, David 2016-08-11T07:00:00Z https://nsuworks.nova.edu/occ_facpresentations/661 unknown NSUWorks https://nsuworks.nova.edu/occ_facpresentations/661 Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures Marine Biology Oceanography and Atmospheric Sciences and Meteorology conference 2016 ftnsoutheastern 2022-04-10T22:08:40Z Background/Question/Methods Seabirds outside the Northeast Pacific and Northeast Atlantic regions are poorly understood from a trophic perspective. To elucidate trophic level relationships, we examined the concentration of ∂13C and ∂15N in the blood, breast muscle, and feathers (proximal and distal sections) of nine species of adult marine-associated birds commonly found in South Florida: osprey Pandion haliaetus (n=1), black skimmer Rynchops niger (n=1), brown pelican Pelecanus occidentalis (n=36), northern gannet Morus bassanus (n=19), double-crested cormorant Phalacrocorax auritus (n=22), royal tern Thalasseus maximus (n=7), herring gull Larus argentatus (n=5), laughing gull Leucophaeus atricilla (n=11), and ring-billed gull Larus delawarensis (n=3). We collected specimens from four wildlife rehabilitation centers after death due to trauma or illness; specimens were frozen at the respective centers and dissected in the laboratory. Three centers (Broward and Dade counties) were in mainland-coastal areas, while one (Monroe county; Florida Keys) was in a coastal-island environment. Tissues were compared between species and tissue types to determine patterns of ∂13C and ∂15N enrichment. Results/Conclusions Calculated mean trophic levels (TLs) of all study species ranged from 5.15 (osprey and northern gannet) to 3.64 (ring-billed gull), findings consistent with existing diet information, and all species exhibited expected ∂13C:∂15N ratios. Broadly varying, but consistent, relationships were seen between tissues, with blood:feather comparisons showing the largest differences. Herring and laughing gulls (TL 4.59 and 3.90, respectively) appear to have a straight trophic enrichment based on coastal POM, although perhaps influenced by occasional anthropogenic waste. Northern gannets (TL 5.15) are likely consuming a limited diet in offshore areas consistent with POM-based enrichment patterns and feeding strategies. Brown pelicans, osprey, and royal terns (TLs 4.78, 5.15, and 4.11, respectively) overlap diets when in the South Florida region, likely reflecting feeding areas; consistent with field observations, when onshore winds are strong, these species feed inshore on carbon-enriched prey, but when winds are weak, they feed near/offshore on carbon-depleted prey, such as lipid-rich fishes. However, cormorants (TLs 3.40 to 5.59) appear to have an unusally bifurcated ∂13C and ∂15N signal between specimens, apparently representing the two habitats inhabited by individual birds in South Florida: one along the coastal/nearshore ecotone (Monroe county) and one along the inland/coastal ecotone (Dade and Broward counties). Conference Object Northeast Atlantic osprey Pandion haliaetus Nova Southeastern University: NSU Works Monroe ENVELOPE(-46.050,-46.050,-60.600,-60.600) Pacific |
institution |
Open Polar |
collection |
Nova Southeastern University: NSU Works |
op_collection_id |
ftnsoutheastern |
language |
unknown |
topic |
Marine Biology Oceanography and Atmospheric Sciences and Meteorology |
spellingShingle |
Marine Biology Oceanography and Atmospheric Sciences and Meteorology Young, Michael Hirons, Amy Martinez, Zara Kerstetter, David Assessment of Trophic Positions for the Seabirds of South Florida using 13C and 15N Stable Iotopes |
topic_facet |
Marine Biology Oceanography and Atmospheric Sciences and Meteorology |
description |
Background/Question/Methods Seabirds outside the Northeast Pacific and Northeast Atlantic regions are poorly understood from a trophic perspective. To elucidate trophic level relationships, we examined the concentration of ∂13C and ∂15N in the blood, breast muscle, and feathers (proximal and distal sections) of nine species of adult marine-associated birds commonly found in South Florida: osprey Pandion haliaetus (n=1), black skimmer Rynchops niger (n=1), brown pelican Pelecanus occidentalis (n=36), northern gannet Morus bassanus (n=19), double-crested cormorant Phalacrocorax auritus (n=22), royal tern Thalasseus maximus (n=7), herring gull Larus argentatus (n=5), laughing gull Leucophaeus atricilla (n=11), and ring-billed gull Larus delawarensis (n=3). We collected specimens from four wildlife rehabilitation centers after death due to trauma or illness; specimens were frozen at the respective centers and dissected in the laboratory. Three centers (Broward and Dade counties) were in mainland-coastal areas, while one (Monroe county; Florida Keys) was in a coastal-island environment. Tissues were compared between species and tissue types to determine patterns of ∂13C and ∂15N enrichment. Results/Conclusions Calculated mean trophic levels (TLs) of all study species ranged from 5.15 (osprey and northern gannet) to 3.64 (ring-billed gull), findings consistent with existing diet information, and all species exhibited expected ∂13C:∂15N ratios. Broadly varying, but consistent, relationships were seen between tissues, with blood:feather comparisons showing the largest differences. Herring and laughing gulls (TL 4.59 and 3.90, respectively) appear to have a straight trophic enrichment based on coastal POM, although perhaps influenced by occasional anthropogenic waste. Northern gannets (TL 5.15) are likely consuming a limited diet in offshore areas consistent with POM-based enrichment patterns and feeding strategies. Brown pelicans, osprey, and royal terns (TLs 4.78, 5.15, and 4.11, respectively) overlap diets when in the South Florida region, likely reflecting feeding areas; consistent with field observations, when onshore winds are strong, these species feed inshore on carbon-enriched prey, but when winds are weak, they feed near/offshore on carbon-depleted prey, such as lipid-rich fishes. However, cormorants (TLs 3.40 to 5.59) appear to have an unusally bifurcated ∂13C and ∂15N signal between specimens, apparently representing the two habitats inhabited by individual birds in South Florida: one along the coastal/nearshore ecotone (Monroe county) and one along the inland/coastal ecotone (Dade and Broward counties). |
format |
Conference Object |
author |
Young, Michael Hirons, Amy Martinez, Zara Kerstetter, David |
author_facet |
Young, Michael Hirons, Amy Martinez, Zara Kerstetter, David |
author_sort |
Young, Michael |
title |
Assessment of Trophic Positions for the Seabirds of South Florida using 13C and 15N Stable Iotopes |
title_short |
Assessment of Trophic Positions for the Seabirds of South Florida using 13C and 15N Stable Iotopes |
title_full |
Assessment of Trophic Positions for the Seabirds of South Florida using 13C and 15N Stable Iotopes |
title_fullStr |
Assessment of Trophic Positions for the Seabirds of South Florida using 13C and 15N Stable Iotopes |
title_full_unstemmed |
Assessment of Trophic Positions for the Seabirds of South Florida using 13C and 15N Stable Iotopes |
title_sort |
assessment of trophic positions for the seabirds of south florida using 13c and 15n stable iotopes |
publisher |
NSUWorks |
publishDate |
2016 |
url |
https://nsuworks.nova.edu/occ_facpresentations/661 |
long_lat |
ENVELOPE(-46.050,-46.050,-60.600,-60.600) |
geographic |
Monroe Pacific |
geographic_facet |
Monroe Pacific |
genre |
Northeast Atlantic osprey Pandion haliaetus |
genre_facet |
Northeast Atlantic osprey Pandion haliaetus |
op_source |
Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures |
op_relation |
https://nsuworks.nova.edu/occ_facpresentations/661 |
_version_ |
1766143521411039232 |