DOI: 10.5061/dryad.5dv41ns6f
title: Body size, trophic position, and the coupling of different energy pathways across a saltmarsh landscape

description: Here, we listed the bulk stable isotope values (δ13C and δ15N) and body
 size measurements of organisms that were analyzed in the manuscript
 "Body size, trophic position, and the coupling of different energy
 pathways across a saltmarsh landscape", published in Limnology and
 Oceanography Letters. Our dataset is a compilation of samplings obtained
 by the Southern Louisiana marsh food webs project within the Coastal
 Waters Consortium (CWC) II (Lopez-Duarte et al. 2017a
 [https://doi.org/10.7266/N7XS5SGD], Lopez-Duarte et al. 2017b
 [https://doi.org/10.7266/N79W0CJW], Polito et al. 2019
 [https://doi.org/10.7266/n7-6277-1216]). The dataset consists of 1563
 individual samples from 77 taxa, including basal sources (plants,
 phytoplankton, detritus, and microphytobenthos), fishes, invertebrates
 (insects, crustaceans, and spiders), infauna, seaside sparrows (Ammospiza
 maritima), and marsh rice rats (Oryzomys palustris). Samplings were
 conducted in three sites, Bay Sansbois, Bay Batiste, and West Pointe à la
 Hache, located in northeastern Barataria Bay. Bay Sansbois and Bay Batiste
 were sampled in May and October 2015, and May 2016, whereas West Pointe à
 la Hache was sampled only in May 2016. Body size measurements are
 available for 59% of all samples (52 taxa) while δ13C and δ15N are
 available for all samples.
description: Samplings were conducted in three sites, Bay Sansbois, Bay
 Batiste, and West Pointe à la Hache, located in the northeastern Barataria
 Bay. Bay Sansbois and Bay Batiste were sampled in May and October of 2015,
 and May of 2016, whereas West Pointe à la Hache was sampled only in May of
 2016. Fishes were sampled using multiple fishing gears
 (minnow traps, seines, trawls, and gill nets) and frozen upon capture.
 Minnow traps baited with dog food were placed in ponds, creeks, and the
 edge of the marshes. Trawl samplings (5-m otter trawl behind a vessel
 traveling ~2.5 knots) were carried out along the marsh channel while gill
 nets (Memphis Net and Twine: 1-1/2-inch, 3-inch, 8-inch deep) were set in
 creeks.  Seine net (Memphis Net and Twine: 25 ft long, 4 ft high, 1/4-in
 mesh) samplings were focused on ponds and creeks. For each specimen
 collected, a sample of the white tissue located on the dorsal region of
 the body was taken. The most common marsh plant species
 were sampled in each site by clipping them at ground level. For this
 study, we analyzed only samples from fresh leaves. Phytoplankton was
 obtained from water sampled at the marsh main channel. Water samples were
 passed it through 105μm mesh screens to remove most zooplankton and large
 debris and then filtered through pre-combusted Whatmann GF/F glass-fiber
 filters. Chlorophyll was measured on the screened and unscreened water to
 determine how much of the phytoplankton were excluded by the screening. 
 We found that on average 93% of phytoplankton chlorophyll was included in
 our samples.  Detritus, which consisted of soil organic matter, was
 obtained from the upper 1-2cm of marsh soil. Microphytobenthos was
 extracted from the upper 1-2cm of marsh soil. Extraction methods are based
 on the protocol described by Levin & Currin (2012).
 Terrestrial insects and spiders were collected using sweep nets
 along a transect from the border of the marsh to 20m inland, covering an
 area of approximately 40 m². Other invertebrates common to saltmarshes,
 including crabs, snails, and mussels, were sampled opportunistically by
 hand or indirectly through sampling techniques (e.g., seine nets)
 targeting other animal groups. After collection, crabs and mussels were
 dissected to extract soft tissue for stable isotope analysis.
 Marsh rice rats were sampled using baited (oatmeal-peanut butter
 balls) Sherman live traps that were set overnight. Rats were euthanized
 with isoflurane and sampled for muscle tissue. Seaside sparrows were
 flushed into a continuous line of four to five, 12-m mist nets oriented
 perpendicular to the marsh edge. Netted individuals were briefly held in
 cloth bags until euthanized via thoracic compression. All individuals were
 immediately sampled for muscle tissue. All isotope
 samples obtained were transported to the lab in coolers with dry ice and
 then sealed and stored in the freezer (-20°C). Samples were cleaned with
 distilled water, lyophilized for 48 hours, and then grounded to a fine
 pounder using pestle and mortar. Next, lipid extraction was conducted
 following chloroform-methanol practices (Folch et al. 1957).  Subsamples
 weighing 0.3-0.5 mg were packed into Ultra-Pure tin capsules and then sent
 to the Great Lakes Institute for Environmental Research Stable Isotope
 Analysis Facility for analysis of stable isotope ratios of δ13C and δ15N.
 The isotope analyses were carried out on a Thermo Finnigan DeltaPlus mass
 spectrometer (Thermo Finnigan San Jose, California, USA) coupled with an
 elemental analyzer (Costech, Valencia, California, USA).
 Body size was measured for 59% of all animals sampled (52 taxa).
 Body mass was measured for the seaside sparrow and marsh rice
 rats whereas body length (e.g., total length for fish, carapace width for
 crabs) was measured for the
 remaining species.
   References: Folch J, Lees
 M, Sloane Stanley GH. 1957. A simple method for the isolation and
 purification of total lipides from animal tissues. Journal of Biological
 Chemistry 226: 497–509. Levin LA, Carolyn C. 2012.
 Stable isotope protocols: Sampling and sample processing. UC San Diego:
 Library – Scripps Digital Collection. Retrieved from
 https://escholarship.org/uc/item/3jw2v1hh