Data Name (This will be the displayed title in Catalog)
Expected Number of Species
Indicator Name (as exists in ecodata)
exp_n
Family (Which group is this indicator associated with?)
[ ] Oceanographic
[ ] Habitat
[ ] Lower trophic levels
[X] Megafauna
[ ] Social
[ ] Economic
Data Description
Diversity metric from the Northeast Fisheries Science Center (NEFSC) Bottom Trawl Surveys.
Introduction to Indicator (Please explain your indicator)
Diversity estimates have been developed to understand whether the overall structure of the ecosystem has remained stable or is changing. There are a large number of diversity indices that can be used to measure diversity; for the purposes of the State of the Ecosystem report we report on the expected number of species in a sample size (E(Sn)). These “rarefied” samples allow for comparisons between sample sites with varying number of species present. The estimate of (E(Sn) is less biased than other diversity indices which usually increase with sample size. It also has a more meaningful biological interpretation than other indices. For example, if a predator eats 10 random individuals,
E(Sn) will predict the number of species consumed.
Key Results and Visualization
Due to the shift to the NOAA vessel Henry B. Bigelow in 2009 and the inability to correct for species composition, the time series is broken into Albatross and Bigelow stanzas. The only apparent trend in the data is from the Albatross time period in the Gulf of Maine.
Implications
Diversity is used as a proxy for stability. Changes in ecological diversity over time may indicate altered ecosystem structure with implications for fishery productivity and management [@friedland_changes_2020]. This indicator shows that the underlying ecosystem is relatively stable with the possibility that the Gulf of Maine is becoming more diverse. Increasing adult diversity in the Gulf of Maine suggests an increase in warm-water species and should be closely monitored.
Spatial Scale
By EPU
Temporal Scale
Spring (March-May) and Fall (September-November)
Synthesis Theme
[X] Multiple System Drivers
[X] Regime Shifts
[X] Ecosystem Reorganization
Define Variables
1) Name: Season Region Expected Number of Species - Vessel; Definition: The expected number of species per 1000 randomly sampled individuals from a region for a given season on either the Albatross or Bigelow. For example "FALL GB Expected Number of Species - Albatross"; Units: n species per 1000 ind.
2) Name: Season Region Expected Number of Species Standard Deviation - Vessel; Definition: The variance around the expected number of species per 1000 randomly sampled individuals from a region for a given season on either the Albatross or Bigelow. For example "FALL GB Expected Number of Species Standard Deviation - Albatross"; Units: n species per 1000 ind.
Primary Contact
Sean.Lucey@NOAA.gov
Secondary Contact
Andrew.Beet@NOAA.gov
Data Name (This will be the displayed title in Catalog)
Expected Number of Species
Indicator Name (as exists in ecodata)
exp_n
Family (Which group is this indicator associated with?)
Data Description
Diversity metric from the Northeast Fisheries Science Center (NEFSC) Bottom Trawl Surveys.
Introduction to Indicator (Please explain your indicator)
Diversity estimates have been developed to understand whether the overall structure of the ecosystem has remained stable or is changing. There are a large number of diversity indices that can be used to measure diversity; for the purposes of the State of the Ecosystem report we report on the expected number of species in a sample size (E(Sn)). These “rarefied” samples allow for comparisons between sample sites with varying number of species present. The estimate of (E(Sn) is less biased than other diversity indices which usually increase with sample size. It also has a more meaningful biological interpretation than other indices. For example, if a predator eats 10 random individuals,
E(Sn) will predict the number of species consumed.
Key Results and Visualization
Due to the shift to the NOAA vessel Henry B. Bigelow in 2009 and the inability to correct for species composition, the time series is broken into Albatross and Bigelow stanzas. The only apparent trend in the data is from the Albatross time period in the Gulf of Maine.
Implications
Diversity is used as a proxy for stability. Changes in ecological diversity over time may indicate altered ecosystem structure with implications for fishery productivity and management [@friedland_changes_2020]. This indicator shows that the underlying ecosystem is relatively stable with the possibility that the Gulf of Maine is becoming more diverse. Increasing adult diversity in the Gulf of Maine suggests an increase in warm-water species and should be closely monitored.
Spatial Scale
By EPU
Temporal Scale
Spring (March-May) and Fall (September-November)
Synthesis Theme
Define Variables
1) Name: Season Region Expected Number of Species - Vessel; Definition: The expected number of species per 1000 randomly sampled individuals from a region for a given season on either the Albatross or Bigelow. For example "FALL GB Expected Number of Species - Albatross"; Units: n species per 1000 ind. 2) Name: Season Region Expected Number of Species Standard Deviation - Vessel; Definition: The variance around the expected number of species per 1000 randomly sampled individuals from a region for a given season on either the Albatross or Bigelow. For example "FALL GB Expected Number of Species Standard Deviation - Albatross"; Units: n species per 1000 ind.
Indicator Category
If other, please specify indicator category
No response
Data Contributors
Sean Lucey, Andrew Beet, and Sarah Gaichas.
Point(s) of Contact
Andrew Beet (Andrew.Beet@NOAA.gov)
Affiliation
NEFSC
Public Availability
Source data are publicly available.
Accessibility and Constraints
No response