Fig 1.
NES study system with the location of stations from the bottom trawl survey core strata shown in red. Blue lines denote divisions of the core area into a northern band above 41.75°N, a southern band located below 40°N, and a middle band in between. Dashed line marks the 100m depth contour.
Table 1.
Number of sample stations and their average position.
Mean longitude and latitude (Lon and Lat) with respective standard deviations (SD) for trawl stations (n, number of stations) within core survey strata during spring and autumn. Longitude and latitude outside mean ±SD are highlighted; also highlighted are years with fewer than 200 trawl stations.
Fig 2.
Trend in species richness for all species.
Estimated species richness as number of species for all taxa over the full extent of the survey in a given year (a). Estimated species richness for all species within the core strata of the survey only (b). No trend tests were conducted on the data in panel (a) since there is no standardizing criteria applied. Data in panel b were tested for trend, solid lines indicate trends found significant at p<0.01. Error bars for estimated number of species are standard errors.
Table 2.
Trend tests for species richness by species groups.
Theil–Sen estimators of trend (expressed as decadal rates) by species group and season with associated p-value of Mann-Kendall Test For Monotonic Trend.
Fig 3.
Trend in species richness by taxonomic groups.
Estimated species richness as number of species for vertebrate (a) and invertebrate (b) taxa over the core strata of the survey by season. Solid lines indicate trends found significant at p<0.01. Error bars for estimated number of species are standard errors.
Fig 4.
Trend in species richness by fish groups.
Estimated species richness as number of species for Osteichthyes (a) and Chondrichthyes (b) taxa over the core strata of the survey by season. Solid lines indicate trends found significant at p<0.01, the absence of a line indicates a non-significant trend. Error bars for estimated number of species are standard errors.
Fig 5.
Trend in species richness by functional groups.
Estimated species richness as number of species for Benthivores (a), Piscivores (b), and Planktivores (c) taxa over the core strata of the survey by season. Solid lines indicate trends found significant at p<0.01, the absence of a line indicates a non-significant trend. Error bars for estimated number of species are standard errors.
Fig 6.
Trend in species richness by latitude band and season.
Estimated species richness as number of species for the northern (a), middle (b), and southern (c) latitude band over the core strata of the survey by season. Solid lines indicate trends found significant at p<0.01, the absence of a line indicates a non-significant trend. Error bars for estimated number of species are standard errors.contour.
Table 3.
Trend tests for species richness by latitude band.
Theil–Sen estimators of trend (expressed as decadal rates) by latitude band and season with associated p-value of Mann-Kendall Test For Monotonic Trend.
Fig 7.
Species richness and forcing factors in spring.
Scatterplots of species richness as number of species by taxonomic and functional groups versus NES Biomass, mean annual surface temperature (ST), and mean annual bottom temperature (BT). Species groups include: All species (ALL, a,b,c); vertebrates (VER, d,e,f); invertebrates (INV, g,h,i); Osteichthyes (OST, j,k,l); Chondrichthyes (CHO, m,n,o); Benthivores (BEN, p,q,r); Piscivores (PIS, s,t,u); and, Planktivores (PLA, v,w,x). In each scatterplot, the absence of line indicate a non- significant correlation with a p>0.05, dashed line indicates a significant correlation of p≤0.05, and a solid line indicates a significant correlation of p≤0.01.
Fig 8.
Species richness and forcing factors in autumn.
Scatterplots of species richness as number of species by taxonomic and functional groups versus NES Biomass, mean annual surface temperature (ST), and mean annual bottom temperature (BT). Species groups include: All species (ALL, a,b,c); vertebrates (VER, d,e,f); invertebrates (INV, g,h,i); Osteichthyes (OST, j,k,l); Chondrichthyes (CHO, m,n,o); Benthivores (BEN, p,q,r); Piscivores (PIS, s,t,u); and, Planktivores (PLA, v,w,x). In each scatterplot, the absence of line indicate a non- significant correlation with a p>0.05, dashed line indicates a significant correlation of p≤0.05, and a solid line indicates a significant correlation of p≤0.01.