Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
• Data Files
• Supplemental Files
• Related Publications
• Parameters
• Instruments
• Project Information
• Funding

Location: Gulf of Mexico Estuary near Port Aransas, Texas. FAML: pier at in Corpus Christi Channel, Port Aransas, TX, United States, Fisheries and Mariculture Laboratory of the University of Texas Marine Science Institute (lat. 27.8396111, lon. -97.0827222); MI: Mud Island in Aransas Bay, TX, United States (lat. 27.9362222, lon. -97.0217777)).

RNA:DNA ratios, which are indicators of animal condition, were measured for samples of egg consumers collected from the field as well as those used in laboratory experiments. Samples of small fishes were collected with cast nets or seines. Fishes were euthanized with lethal dose of MS-222. The euthanized fish were placed on ice and muscle plugs were collected. All samples were lyophilized and stored at -80°C until being processed for RNA:DNA analysis. The time between collection and analysis ranged from 15 to 444 days. Results of the analysis were reported as the ratio of RNA content to DNA content.

Measurements of RNA:DNA were made on individuals. DNA and RNA were measured using the ethidium bromide (EB) fluorometric technique (Westerman and Holt 1988) based on aliquots (10 µL) of homogenates. Calculations were based upon comparisons with DNA-EB and RNA-EB calibration curves from calf thymus DNA and yeast RNA (Type 111) standards. RNA:DNA ratios were normalized using a standardization factor based on the common RNA:DNA slope ratio procedure described by Caldarone et al. (2006). Results of the analysis were reported as the ratio of RNA content to DNA content. Measurements of RNA:DNA were unsuccessfully attempted for invertebrates.

The microplate fluorometer is operated using SoftMax Pro version 5.4 also by Molecular Devices. Raw data were exported to Microsoft Excel for further processing.

Quality control procedure:

Individual samples for which the means were greater than 3 standard deviations from the taxon mean were removed from the data set.

A primary check value was assigned as follows:

1 Perfectly fine

2 Data not evaluated because of too few data points for quality control check

BCO-DMO Data Manager Processing Notes:
* Sheet 1 of file "RNA DNA field data.xlsx" (submitted in our online submission system 2023-06-23) was imported into the BCO-DMO data system with values "NA" as missing data values. 
** Missing data values are displayed differently based on the file format you download.  They are blank in csv files, "NaN" in MatLab files, etc.
* Column names adjusted to conform to BCO-DMO naming conventions designed to support broad re-use by a variety of research tools and scripting languages. [Only numbers, letters, and underscores.  Can not start with a number]
* Taxon name and associated LSID for names in this dataset as of 2023-06-23 (source: World Register of Marine Species). Added this list to Methods and Sampling section.
* Date formats converted to ISO 8601.
* Site lat and lon added as data columns from values provided in metadata.

After correspondence with the submitter, "Spotfin mojarro, Eucinostomus melanopterus " in this dataset was updated to "Spotfin mojarra, Eucinostomus argenteus"

NSF Award Abstract:
Marine animals release extremely large numbers of eggs when they spawn. Most of these eggs are eaten by animals ranging from microscopic plankton to fish. Many egg consumers are smaller than the animals that released the eggs, representing a reversal of the usual food web. The consumption of eggs provides animals with highly nutritious molecules called essential fatty acids which are very concentrated in eggs. These essential fatty acids are important for the health of animals and the health of the whole ecosystem. When marine fishes form spawning aggregations to coordinate the timing and location of spawning, they release trillions of eggs. This results in an "egg boon" an immense but temporary concentration of highly nutritious fatty acids. This project combines field-based sampling with laboratory experiments to assess how fatty acids in the egg boons affect food webs. The project is determining whether consumption of eggs is beneficial to the condition of the egg consumers. New findings from this project are advancing the understanding of aquatic food webs and contributing to improved management of marine resources. For example, commercial harvest of fish can remove tons of fatty acids from an ecosystem by reducing egg boons and leading to cascading and unforeseen effects on those biological communities. The project is fostering the participation of women in science by substantially advancing the professional training of a female postdoctoral fellow. The project is supporting K-12 STEM education through inquiry-based and place-based programs for teachers and youth. Findings are being communicated to the public locally and nationally through participation in public lectures and contributions to the Science and the SeaTM radio program, podcast, and website.

Super-abundances of eggs released in temporally and spatially discrete patches create pulsed nutritional resources for egg consumers, called "egg boons", which are potentially important components of marine food webs. While various marine animals have been shown to consume eggs, the role of egg boons in energy transfer through food webs has received little attention. Three hypotheses are being tested: 1) egg boons provide a pathway through which essential fatty acids (EFAs) are redistributed counter to the main direction of trophic flow; 2) stores of EFAs in egg consumers increase during egg boons and remain elevated after the spawning season; and 3) egg boons are beneficial to the condition of egg consumers. The proposed research takes advantage of an annual egg boon produced by a spawning aggregation of the marine fish, red drum (Sciaenops ocellatus) near Port Aransas, Texas. In a combination of field sampling and laboratory experiments, fatty acid profiles, lipid content, and bulk stable isotope ratios are measures used to define trophic links between the egg boon and a selection of lower-trophic-level taxa. Egg boons are simulated in laboratory feeding experiments that are designed to enhance interpretation of data collected from field based sampling by comparing taxa that consume fish eggs with those that do not. A nucleic acid biomarker (RNA/DNA ratios) is being used to assess changes in condition that can be attributed to egg consumption in target taxa. In the environment, the importance and persistence of counter-gradient flow of fatty acids in the food web is being gauged through comparisons of samples taken inside and outside the spatial and temporal extent of the egg boon. The effects of egg consumption on consumers is being quantified in controlled experiments to identify dietary biomarkers of egg consumption in consumer tissues that can be applied to field samples. The proposed research examines how egg consumption redistributes EFAs within food webs and provides a context for considering potential controls and trophic bottlenecks that cannot be explained from the traditional element-limitation models. The integration of fatty acid and stable isotope approaches is expected to provide greater resolution for tracking organic matter through food webs and to advance the application of multi-tracer techniques in trophic investigations. Further, if egg boons are indeed an important nutritional subsidy to select groups of consumers, then subsequent studies investigating the energetic contribution of egg boons to secondary production in marine food webs are warranted. An analysis of how reduction or removal of egg resources through the harvest of fishes in spawning aggregations changes nutrient flow in food webs could have implications for ecosystem-based fisheries management.