All species of anguilliform eels have pelagic leptocephalus larval stages, which provides a means of monitoring the population dynamics of these otherwise cryptic and hard to study species. The goals of this study were to: 1) describe the distribution and abundance of anguilliform eel leptocephali across the northern Gulf of Mexico, and 2) examine the trophic ecology of leptocephali using stable isotope values of carbon and nitrogen (δ13C and δ15N). A 25-year (1990-2014) ichthyoplankton dataset provided by the National Oceanic and Atmospheric Administration (NOAA) Southeast Area Monitoring and Assessment Program (SEAMAP) was used to examine interannual variations in leptocephalus distribution, abundance, and occurrence. Family-level indices of abundance and occurrence were significantly and positively correlated over the time series within season (spring and fall) and gear types (bongo net and neuston net). Ten of the reported twelve eel families known from the Gulf of Mexico were collected during this time series. Decreases in abundance and occurrence for dominant families (Ophichthidae, Congridae, and Muraenidae) were observed during the latter part of the time series. Leptocephalus, zooplankton, and particulate organic matter (POM) samples were collected during the SEAMAP Fall Plankton Survey in 2016 and analyzed for stable isotopes. Variability in the isotope values of leptocephali was driven by variability in baseline POM isotope values. Diet composition analyses indicated leptocephali used POM and small zooplankton as diet sources. Information about leptocephali taxonomic diversity, abundance, distribution, and trophic ecology add to our understanding of their ecological role in the ocean.
","abstract_html":"<p>All species of anguilliform eels have pelagic leptocephalus larval stages, which provides a means of monitoring the population dynamics of these otherwise cryptic and hard to study species. The goals of this study were to: 1) describe the distribution and abundance of anguilliform eel leptocephali across the northern Gulf of Mexico, and 2) examine the trophic ecology of leptocephali using stable isotope values of carbon and nitrogen (δ13C and δ15N). A 25-year (1990-2014) ichthyoplankton dataset provided by the National Oceanic and Atmospheric Administration (NOAA) Southeast Area Monitoring and Assessment Program (SEAMAP) was used to examine interannual variations in leptocephalus distribution, abundance, and occurrence. Family-level indices of abundance and occurrence were significantly and positively correlated over the time series within season (spring and fall) and gear types (bongo net and neuston net). Ten of the reported twelve eel families known from the Gulf of Mexico were collected during this time series. Decreases in abundance and occurrence for dominant families (Ophichthidae, Congridae, and Muraenidae) were observed during the latter part of the time series. Leptocephalus, zooplankton, and particulate organic matter (POM) samples were collected during the SEAMAP Fall Plankton Survey in 2016 and analyzed for stable isotopes. Variability in the isotope values of leptocephali was driven by variability in baseline POM isotope values. Diet composition analyses indicated leptocephali used POM and small zooplankton as diet sources. Information about leptocephali taxonomic diversity, abundance, distribution, and trophic ecology add to our understanding of their ecological role in the ocean.</p>","abstract_has_math":false,"creators":["Collins, Lillian"],"institution":null,"degree_name":"Master of Science (MS)","degree_level":"Masters Thesis","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Frank Hernandez","Kevin Dillon","Jesse Filbrun"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2019,"date_issued":"2019-12-01T08:00:00Z","date_published":"2019-12-01T08:00:00Z","updated_at":"2026-07-24T05:45:12Z","subjects":["anguilliformes","leptocephali","eel","Marine Biology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://aquila.usm.edu/masters_theses/687","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Frank Hernandez","Kevin Dillon","Jesse Filbrun"]},{"key":"dc:creator","label":"Author","values":["Collins, Lillian"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2019-10-18T07:00:00Z"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Masters Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["anguilliformes","leptocephali","eel","Marine Biology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://aquila.usm.edu/masters_theses/687"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["All species of anguilliform eels have pelagic leptocephalus larval stages, which provides a means of monitoring the population dynamics of these otherwise cryptic and hard to study species. The goals of this study were to: 1) describe the distribution and abundance of anguilliform eel leptocephali across the northern Gulf of Mexico, and 2) examine the trophic ecology of leptocephali using stable isotope values of carbon and nitrogen (δ13C and δ15N). A 25-year (1990-2014) ichthyoplankton dataset provided by the National Oceanic and Atmospheric Administration (NOAA) Southeast Area Monitoring and Assessment Program (SEAMAP) was used to examine interannual variations in leptocephalus distribution, abundance, and occurrence. Family-level indices of abundance and occurrence were significantly and positively correlated over the time series within season (spring and fall) and gear types (bongo net and neuston net). Ten of the reported twelve eel families known from the Gulf of Mexico were collected during this time series. Decreases in abundance and occurrence for dominant families (Ophichthidae, Congridae, and Muraenidae) were observed during the latter part of the time series. Leptocephalus, zooplankton, and particulate organic matter (POM) samples were collected during the SEAMAP Fall Plankton Survey in 2016 and analyzed for stable isotopes. Variability in the isotope values of leptocephali was driven by variability in baseline POM isotope values. Diet composition analyses indicated leptocephali used POM and small zooplankton as diet sources. Information about leptocephali taxonomic diversity, abundance, distribution, and trophic ecology add to our understanding of their ecological role in the ocean.
"]},{"key":"dc:title","label":"Title","values":["Distribution, Abundance, and Trophic Ecology of Anguilliform Leptocephali in the Northern Gulf of Mexico"]}]}],"canonical_facts":{"dc:contributor":["Frank Hernandez","Kevin Dillon","Jesse Filbrun"],"dc:creator":["Collins, Lillian"],"dc:date.available":["2019-10-18T07:00:00Z"],"dc:description.abstract":["All species of anguilliform eels have pelagic leptocephalus larval stages, which provides a means of monitoring the population dynamics of these otherwise cryptic and hard to study species. The goals of this study were to: 1) describe the distribution and abundance of anguilliform eel leptocephali across the northern Gulf of Mexico, and 2) examine the trophic ecology of leptocephali using stable isotope values of carbon and nitrogen (δ13C and δ15N). A 25-year (1990-2014) ichthyoplankton dataset provided by the National Oceanic and Atmospheric Administration (NOAA) Southeast Area Monitoring and Assessment Program (SEAMAP) was used to examine interannual variations in leptocephalus distribution, abundance, and occurrence. Family-level indices of abundance and occurrence were significantly and positively correlated over the time series within season (spring and fall) and gear types (bongo net and neuston net). Ten of the reported twelve eel families known from the Gulf of Mexico were collected during this time series. Decreases in abundance and occurrence for dominant families (Ophichthidae, Congridae, and Muraenidae) were observed during the latter part of the time series. Leptocephalus, zooplankton, and particulate organic matter (POM) samples were collected during the SEAMAP Fall Plankton Survey in 2016 and analyzed for stable isotopes. Variability in the isotope values of leptocephali was driven by variability in baseline POM isotope values. Diet composition analyses indicated leptocephali used POM and small zooplankton as diet sources. Information about leptocephali taxonomic diversity, abundance, distribution, and trophic ecology add to our understanding of their ecological role in the ocean.
"],"dc:identifier":["https://aquila.usm.edu/masters_theses/687"],"dc:subject":["anguilliformes","leptocephali","eel","Marine Biology"],"dc:title":["Distribution, Abundance, and Trophic Ecology of Anguilliform Leptocephali in the Northern Gulf of Mexico"],"thesis:degree_level":["Masters Thesis"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T05:45:12Z"}