[Submission]: Benthic Invertebrate Indices

[sgaichas]

Primary Contact

[email protected]

Secondary Contact

No response

Data Name (This will be the displayed title in Catalog)

Benthic Invertebrate Indices

Indicator Name (as exists in ecodata)

benthos_index

Family (Which group is this indicator associated with?)

• Oceanographic
• Habitat
• Lower trophic levels
• Megafauna
• Social
• Economic

Data Description

Aggregate macrobenthos and megabenthos invertebrate indices from fish stomach contents

Introduction to Indicator (Please explain your indicator)

Benthic invertebrates provide supporting ecosystem services as important prey for many economically important fish species on the Northeast US shelf. Changes to the benthic invertebrate forage base could have important implications for regional food webs. However, we lack direct measurements of benthic invertebrate biomass for most unexploited taxa.

We define Macrobenthos as bottom-dwelling invertebrates retained on a 0.5-1.0 mm sieve. These include polychaete worms, small crustaceans, bivalves (non-commercial), gastropods, nemerteans, tunicates, cnidarians, brittle stars, sea cucumbers, and sand dollars.

We define Megabenthos as sea stars (Echinodermata: Asteroidea) and large Arthropods (horseshoe crabs (Merostomata), mantis shrimp (Crustacea: Stomatopoda), and crabs (Crustacea: Decapoda: Brachyura and Anomura other than hermit crabs)).

The indices developed here use similar methods to the Forage Fish Index. The spatially-explicit macrobenthos and megabenthos indices estimate the combined biomass of 833 and 105 taxa, respectively, using stomach contents information from 88 predator/size combinations from fish collected on bottom trawl surveys.

In addition to an index of benthic invertebrate biomass in each EPU, the coastwide center of gravity for the combined benthic biomass was estimated to evaluate whether distributions of benthic invertebrate biomass have changed over time.

Key Results and Visualization

Time series extend from 1980-2023. Macrobenthos and Megabenthos are included on separate plots for each EPU.

Variables plotted are Fall Macrobenthos or Megabenthos Biomass Estimate and Spring Macrobenthos or Megabenthos Biomass Estimate with error bands from Fall Macrobenthos or Megabenthos Biomass Estimate SE and Spring Macrobenthos or Megabenthos Biomass Estimate SE, respectively.

Eastward and Northward components of the Center of Gravity, along with the Center of Gravity SE are plotted for Fall and Spring Macrobenthos or Megabenthos Biomass.

Implications

Macrobenthos indices show long term declines in spring in all EPUs and coastwide. In contrast, Megabenthos indices show long term increases in fall coastwide and in GOM and GB, and in spring coastwide and in MAB.

Center of gravity indicators show no long term trends for Megabenthos. In contrast, Macrobenthos center of gravity shows a significant long term trend towards the west over time. This is the opposite direction observed for aggregate forage fish and surveyed fish species in aggregate.

Spatial Scale

by EPU and full shelf

Temporal Scale

Spring (January-June), Fall (July-December)

Synthesis Theme

• Multiple System Drivers
• Regime Shifts
• Ecosystem Reorganization

Define Variables

Spring Macrobenthos Biomass Estimate = aggregate macrobenthos biomass months 1-6, units relative grams per stomach
Spring Macrobenthos Biomass Estimate SE = standard error of aggregate macrobenthos biomass months 1-6, units relative grams per stomach
Fall Macrobenthos Biomass Estimate = aggregate macrobenthos biomass months 7-12, units relative grams per stomach
Fall Macrobenthos Biomass Estimate SE = standard error of aggregate macrobenthos biomass months 7-12, units relative grams per stomach
Fall Eastward Macrobenthos Center of Gravity = average eastward location of macrobenthos biomass months 7-12, units kilometers
Fall Eastward Macrobenthos Center of Gravity SE = standard error of average eastward location of macrobenthos biomass months 7-12, units kilometers
Fall Northward Macrobenthos Center of Gravity = average northward location of macrobenthos biomass months 7-12, units kilometers
Fall Northward Macrobenthos Center of Gravity SE = standard error of average northward location of macrobenthos biomass months 7-12, units kilometers
Spring Eastward Macrobenthos Center of Gravity = average eastward location of macrobenthos biomass months 1-6, units kilometers
Spring Eastward Macrobenthos Center of Gravity SE = standard error of average eastward location of macrobenthos biomass months 1-6, units kilometers
Spring Northward Macrobenthos Center of Gravity = average northward location of macrobenthos biomass months 1-6, units kilometers
Spring Northward Macrobenthos Center of Gravity SE = standard error of average northward location of macrobenthos biomass months 1-6, units kilometers
Spring Megabenthos Biomass Estimate = aggregate megabenthos biomass months 1-6, units relative grams per stomach
Spring Megabenthos Biomass Estimate SE = standard error of aggregate megabenthos biomass months 1-6, units relative grams per stomach
Fall Megabenthos Biomass Estimate = aggregate megabenthos biomass months 7-12, units relative grams per stomach
Fall Megabenthos Biomass Estimate SE = standard error of aggregate megabenthos biomass months 7-12, units relative grams per stomach
Fall Eastward Megabenthos Center of Gravity = average eastward location of megabenthos biomass months 7-12, units kilometers
Fall Eastward Megabenthos Center of Gravity SE = standard error of average eastward location of megabenthos biomass months 7-12, units kilometers
Fall Northward Megabenthos Center of Gravity = average northward location of megabenthos biomass months 7-12, units kilometers
Fall Northward Megabenthos Center of Gravity SE = standard error of average northward location of megabenthos biomass months 7-12, units kilometers
Spring Eastward Megabenthos Center of Gravity = average eastward location of megabenthos biomass months 1-6, units kilometers
Spring Eastward Megabenthos Center of Gravity SE = standard error of average eastward location of megabenthos biomass months 1-6, units kilometers
Spring Northward Megabenthos Center of Gravity = average northward location of megabenthos biomass months 1-6, units kilometers
Spring Northward Megabenthos Center of Gravity SE = standard error of average northward location of megabenthos biomass months 1-6, units kilometers

Indicator Category

• Published Methods
• Extensive analysis, not yet published
• Syntheses of published information
• Database pull
• Database pull with analysis
• Other

If other, please specify indicator category

No response

Data Contributors

Sarah Gaichas, James Gartland, Brian E. Smith, Sarah Weisberg, Sean Lucey

Point(s) of Contact

Sarah Gaichas ([email protected])

Affiliation

NEFSC

Public Availability

Source data are publicly available. All data and code available on GitHub at https://github.com/NOAA-EDAB/benthosindex

Accessibility and Constraints

No response