J-3 
dance/biomass or excessive abundance/biomass. The scoring thresholds for 
these two metrics vary with habitat type (salinity regime and substrate type) as 
summarized in Figure J-2. In this process, a site is classified as degraded by 
low dissolved oxygen” if the abundance (and/or biomass) metric scores a 1 
due to insufficient abundance (and/or biomass). Alternatively, if the abundance 
(and/or biomass) metric scores a 1 because of excessive abundance (and/or 
biomass) the site is classified as degraded by “eutrophication”. 
2. Segment classification: The assignment of probable causes of benthic degra¬ 
dation for the overall segment is accomplished using a simple 25% rule. If the 
percent of total sites in a segment impacted by a single cause (i.e. sediment 
contaminants, low dissolved oxygen, or eutrophication) exceeds 25%, then that 
cause is assigned. If no causes exceed 25%, the cause is considered unknown. 
The cause(s) should be identified as a suspected (vs. verified) cause of benthic 
community degradation in the ADB database. 
Table J-l shows the possible conclusions from applying the above protocol. The 
States should carefully review the results from application of the protocol to ensure 
all findings and conclusions are rational and reasonable. Best profession judgment, 
common sense, and ancillary information about each segment should be utilized as 
necessary and available. 
Habitat 
Metric 
Lower Limit 
(Metric 
Score=1) 
Upper Limit 
(Metric 
Score=1) 
Tidal Freshwater 
Abundance (# m-2) 
Biomass (q m-2) 
<800 
a 5500 
Oligohaline 
Abundance (U m-2) 
Biomass (g m-2) 
<180 
2 4050 
Low Mesohaline 
Abundance (# m-2) 
Biomass (g m-2) 
<500 
<1 
2 6000 
2 30 
High Mesohaline Sand 
Abundance (# m-2) 
Biomass (g m-2) 
<1000 
<1 
5 5000 
2 50 
High Mesohaline Mud 
Abundance (# m-2) 
Biomass (g m-2) 
<1000 
<0.5 
a 5000 
> 50 
Polyhaline Sand 
Abundance (# m-2) 
Biomass (g m-2) 
<1500 
<1 
2 8000 
2 50 
Polyhaline Mud 
Abundance (# m-2) 
Biomass (g m-2) 
<1000 
<0.5 
2 8000 
2 30 
Figure J-2. Metric scoring for eutrophication and low dissolved oxygen causes. 
Source: Llanso 2002, Table 9, pages 24-26. 
appendix j • Bay Estuarine Benthic Communities Assessment Protocol tor Maryland and Virginia 
