Why stop at the surface when addressing marine ecosystems? A preliminary assessment of trophic positions for the seabirds of south Florida using C and N stable isotopes
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...
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ftnsoutheastern:oai:nsuworks.nova.edu:cnso_osj-1044 2023-05-15T17:41:47+02:00 Why stop at the surface when addressing marine ecosystems? A preliminary assessment of trophic positions for the seabirds of south Florida using C and N stable isotopes Kerstetter, David 2016-05-20T21:30:00Z https://nsuworks.nova.edu/cnso_osj/may-2016/day2/19 unknown NSUWorks https://nsuworks.nova.edu/cnso_osj/may-2016/day2/19 HCAS Ocean Science Research Symposium Marine Biology Oceanography article 2016 ftnsoutheastern 2022-04-10T21:44:02Z 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. 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). Article in Journal/Newspaper 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 |
spellingShingle |
Marine Biology Oceanography Kerstetter, David Why stop at the surface when addressing marine ecosystems? A preliminary assessment of trophic positions for the seabirds of south Florida using C and N stable isotopes |
topic_facet |
Marine Biology Oceanography |
description |
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. 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 |
Article in Journal/Newspaper |
author |
Kerstetter, David |
author_facet |
Kerstetter, David |
author_sort |
Kerstetter, David |
title |
Why stop at the surface when addressing marine ecosystems? A preliminary assessment of trophic positions for the seabirds of south Florida using C and N stable isotopes |
title_short |
Why stop at the surface when addressing marine ecosystems? A preliminary assessment of trophic positions for the seabirds of south Florida using C and N stable isotopes |
title_full |
Why stop at the surface when addressing marine ecosystems? A preliminary assessment of trophic positions for the seabirds of south Florida using C and N stable isotopes |
title_fullStr |
Why stop at the surface when addressing marine ecosystems? A preliminary assessment of trophic positions for the seabirds of south Florida using C and N stable isotopes |
title_full_unstemmed |
Why stop at the surface when addressing marine ecosystems? A preliminary assessment of trophic positions for the seabirds of south Florida using C and N stable isotopes |
title_sort |
why stop at the surface when addressing marine ecosystems? a preliminary assessment of trophic positions for the seabirds of south florida using c and n stable isotopes |
publisher |
NSUWorks |
publishDate |
2016 |
url |
https://nsuworks.nova.edu/cnso_osj/may-2016/day2/19 |
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 |
HCAS Ocean Science Research Symposium |
op_relation |
https://nsuworks.nova.edu/cnso_osj/may-2016/day2/19 |
_version_ |
1766143518499143680 |