Fatty acid trophic markers and trophic links among seston, crustacean zooplankton and the siphonophore Nanomia cara in Georges Basin and Oceanographer Canyon (NW Atlantic)

A grant to MJY from the National Science Foundation (NSF-0002493), and USDa CRIS Project FLA-FAS-03978 supported this work. This is contribution no. 1696 to the Harbor Branch Oceanographic Institution.Fatty acid concentrations expressed as percentages of total fatty acid pools in seston, stage V copepodites of Calanus finmarchicus, adults of the euphausiid Meganyctiphanes norvegica, and the physonect siphonophore Nanomia cara were used to elucidate trophic links in Georges Basin and Oceanographer Canyon in September 2003. Seston at both locations was refractory and comprised mainly of saturated fatty acids. Phytoplankton did not contribute significantly to the fatty acid composition of seston or higher trophic levels. Only four fatty acids, i.e. 14:0, 16:0, 16:1 (n-7) and 18:1 (n-7), were transferred from seston to C. finmarchicus or M. norvegica, which suggested weak trophic interactions. Fatty acids transferred from the two species of crustaceans to N. cara included the same four fatty acids, along with three polyunsaturated fatty acids found in relatively high concentrations in both crustaceans, i.e. 20:3 (n-6), 20:5 (n-3) and 22:6 (n-3). In addition, 18:1 (n-9), which occurred in relatively high concentrations only in M. norvegica, and 18:0 and 18:2 (n-6), which were found in low concentrations in both crustaceans, also appeared to be transferred to N. cara. Overall, fatty acid trophic markers proved useful for identifying trophic links to N. cara.En este estudio se utilizaron las concentraciones de ácidos grasos (expresadas como porcentajes) para identificar posibles relaciones tróficas entre el seston, el estadio V (copepoditos) de Calanus finmarchicus, los adultos del eufáusido Meganyctiphanes norvegica, y el sifonóforo fisonecto Nanomia cara en Georges Basin y el cañón submarino Oceanographer durante Septiembre de 2003. En ambos lugares el seston era muy refractario y compuesto básicamente por ácidos grasos saturados. El fitoplancton no contribuyó de forma significativa a la composición de ácidos grasos del seston o de niveles tróficos superiores. Sólo cuatro ácidos grasos [14:0, 16:0, 16:1 (n-7) y 18:1 (n-7)] se transfirieron potencialmente del seston a C. finmarchicus o M. norvegica, lo que sugiere una débil conexión trófica entre estos eslabones de la cadena. Los ácidos grasos transferidos de las dos especies de zooplancton crustáceo a N. cara incluyen los mismos descritos más arriba y otros tres ácidos grasos poliinsaturados [20:3 (n-6), 20:5 (n-3) y 22:6 (n-3)] encontrados en concentraciones relativamente elevadas en ambos crustáceos. Además, tanto el 18:1 (n-9) (encontrado en elevadas concentraciones en M. norvegica) y los 18:0 y 18:2 (n-6) (encontrados en bajas concentraciones en ambas especies de crustáceos) se transfieren a N. cara. Los ácidos grasos demuestran ser una herramienta útil para identificar conexiones tróficas en N. cara

Net negative growth detected in a population of Leptogorgia sarmentosa: quantifying the biomass loss in a benthic soft bottom-gravel gorgonian

13 pages, 7 figures, 4 tablesGorgonian species may contribute to the three-dimensional seascape in soft bottom-gravel areas, but the information on their biology and ecology is very scarce. The biometry and secondary production of the Mediterranean soft bottom-gravel passive suspension feeder Leptogorgia sarmentosa (Cnidaria: Octocorallia) was studied using photographic monitoring of the primary branches from May 1998 to September 2000. The primary branches observed had a high density of polyps (2.2 ± 0.2 SD polyps mm−1) and a high organic matter content (63.2 ± 9.1 SD %). During the two-year sampling period, there was a net negative growth in 90% of the gorgonian population. The mean loss during the 27-month period was −2.9 ± 0.9 SD cm per branch (5.7 mg C branch−1). However, considering only the initial and final diameters and maximum height in the 27 months elapsed time, the gorgonians showed positive growth, which meant that photographic sampling of single branches was a more appropriate method for gorgonian secondary production monitoring. A water mass anomaly detected in 1999 in the north-western Mediterranean Sea may have been the cause of the net negative growth in L. sarmentosa in the studied area. Partial mortality due to different factors, such as strong currents, predation, disease, etc., could be a common strategy in sessile colonial benthic populations that would facilitate their maintenance even during very stressful circumstancesSupport for this work was provided by an F.P.I. fellowship from the Spanish Ministry of Education and Culture (MEC), which was granted to SR under D.G.I.C.Y.T. project PB94-0014-C02-01, and Ramón y Cajal contract RyC-2007-01327Peer reviewe

X.; Fatty acid trophic markers and trophic links among seston, crustacean zooplankton and the siphonophore Nanomia cara

SuMMarY: Fatty acid concentrations expressed as percentages of total fatty acid pools in seston, stage V copepodites of Calanus finmarchicus, adults of the euphausiid Meganyctiphanes norvegica, and the physonect siphonophore Nanomia cara were used to elucidate trophic links in georges basin and oceanographer Canyon in September 2003. Seston at both locations was refractory and comprised mainly of saturated fatty acids. Phytoplankton did not contribute significantly to the fatty acid composition of seston or higher trophic levels. only four fatty acids, i.e. 14:0, 16:0, 16:1 (n-7) and 18:1 (n-7), were transferred from seston to C. finmarchicus or M. norvegica, which suggested weak trophic interactions. Fatty acids transferred from the two species of crustaceans to N. cara included the same four fatty acids, along with three polyunsaturated fatty acids found in relatively high concentrations in both crustaceans, i.e. 20:3 (n-6), 20:5 (n-3) and 22:6 (n-3). in addition, 18:1 (n-9), which occurred in relatively high concentrations only in M. norvegica, and 18:0 and 18:2 (n-6), which were found in low concentrations in both crustaceans, also appeared to be transferred to N. cara. overall, fatty acid trophic markers proved useful for identifying trophic links to N. cara. Keywords: fatty acids, trophic relationships, siphonophora, gulf of Maine. reSuMen: Ácidos grasos como marcadores de las relaciones tróficas entre el seston, el zooplancton crustáceo y el sifonóforo NaNomia cara en Georges Basin y el cañón Oceanographer (NO Atlántico). -en este estudio se utilizaron las concentraciones de ácidos grasos (expresadas como porcentajes) para identificar posibles relaciones tróficas entre el seston, el estadio V (copepoditos) de Calanus finmarchicus, los adultos del eufáusido Meganyctiphanes norvegica, y el sifonóforo fisonecto Nanomia cara en georges basin y el cañón submarino oceanographer durante Septiembre de 2003. en ambos lugares el seston era muy refractario y compuesto básicamente por ácidos grasos saturados. el fitoplancton no contribuyó de forma significativa a la composición de ácidos grasos del seston o de niveles tróficos superiores. Sólo cuatro ácidos grasos [14:0, 16:0, 16:1 (n-7) y 18:1 (n-7)] se transfirieron potencialmente del seston a C. finmarchicus o M. norvegica, lo que sugiere una débil conexión trófica entre estos eslabones de la cadena. los ácidos grasos transferidos de las dos especies de zooplancton crustáceo a N. cara incluyen los mismos descritos más arriba y otros tres ácidos grasos poliinsaturados [20:3 (n-6), 20:5 (n-3) y 22:6 (n-3)] encontrados en concentraciones relativamente elevadas en ambos crustáceos. además, tanto el 18:1 (n-9) (encontrado en elevadas concentraciones en M. norvegica) y los 18:0 y 18:2 (n-6) (encontrados en bajas concentraciones en ambas especies de crustáceos) se transfieren a N. cara. los ácidos grasos demuestran ser una herramienta útil para identificar conexiones tróficas en N. cara

Fatty acid trophic markers and trophic links among seston, crustacean zooplankton and the siphonophore Nanomia cara in Georges Basin and Oceanographer Canyon (NW Atlantic)

A grant to MJY from the National Science Foundation (NSF-0002493), and USDa CRIS Project FLA-FAS-03978 supported this work. This is contribution no. 1696 to the Harbor Branch Oceanographic Institution.Fatty acid concentrations expressed as percentages of total fatty acid pools in seston, stage V copepodites of Calanus finmarchicus, adults of the euphausiid Meganyctiphanes norvegica, and the physonect siphonophore Nanomia cara were used to elucidate trophic links in Georges Basin and Oceanographer Canyon in September 2003. Seston at both locations was refractory and comprised mainly of saturated fatty acids. Phytoplankton did not contribute significantly to the fatty acid composition of seston or higher trophic levels. Only four fatty acids, i.e. 14:0, 16:0, 16:1 (n-7) and 18:1 (n-7), were transferred from seston to C. finmarchicus or M. norvegica, which suggested weak trophic interactions. Fatty acids transferred from the two species of crustaceans to N. cara included the same four fatty acids, along with three polyunsaturated fatty acids found in relatively high concentrations in both crustaceans, i.e. 20:3 (n-6), 20:5 (n-3) and 22:6 (n-3). In addition, 18:1 (n-9), which occurred in relatively high concentrations only in M. norvegica, and 18:0 and 18:2 (n-6), which were found in low concentrations in both crustaceans, also appeared to be transferred to N. cara. Overall, fatty acid trophic markers proved useful for identifying trophic links to N. cara.En este estudio se utilizaron las concentraciones de ácidos grasos (expresadas como porcentajes) para identificar posibles relaciones tróficas entre el seston, el estadio V (copepoditos) de Calanus finmarchicus, los adultos del eufáusido Meganyctiphanes norvegica, y el sifonóforo fisonecto Nanomia cara en Georges Basin y el cañón submarino Oceanographer durante Septiembre de 2003. En ambos lugares el seston era muy refractario y compuesto básicamente por ácidos grasos saturados. El fitoplancton no contribuyó de forma significativa a la composición de ácidos grasos del seston o de niveles tróficos superiores. Sólo cuatro ácidos grasos [14:0, 16:0, 16:1 (n-7) y 18:1 (n-7)] se transfirieron potencialmente del seston a C. finmarchicus o M. norvegica, lo que sugiere una débil conexión trófica entre estos eslabones de la cadena. Los ácidos grasos transferidos de las dos especies de zooplancton crustáceo a N. cara incluyen los mismos descritos más arriba y otros tres ácidos grasos poliinsaturados [20:3 (n-6), 20:5 (n-3) y 22:6 (n-3)] encontrados en concentraciones relativamente elevadas en ambos crustáceos. Además, tanto el 18:1 (n-9) (encontrado en elevadas concentraciones en M. norvegica) y los 18:0 y 18:2 (n-6) (encontrados en bajas concentraciones en ambas especies de crustáceos) se transfieren a N. cara. Los ácidos grasos demuestran ser una herramienta útil para identificar conexiones tróficas en N. cara