DOI: 10.5061/dryad.47d7wm3m0
title: Density data for Lake Erie benthic invertebrate assemblages from 1930 to 2019

description: Benthic invertebrates are important trophic links in food webs and useful
 bioindicators of environmental conditions, but long-term benthic organism
 abundance data across broad geographic areas are rare, and historic data
 sets are often not readily accessible. This data set for a companion paper
 by Karatayev et al. (2022) provides densities of benthic
 macroinvertebrates collected from 1930 to 2019 during surveys in Lake
 Erie, a Laurentian Great Lake. The surveys were funded by the governments
 of the United States and Canada to investigate the status and changes in
 benthic community. From the total of 21 lake- and basin-wide benthic
 surveys conducted in Lake Erie from 1929 to 2019, we were able to acquire
 data for 17 surveys, including species-level data for 10 surveys and data
 by higher taxonomic groups for 7 surveys. Our amassed Lake Erie dataset
 includes data from 11 surveys (including 5 with species-level data)
 conducted in the western basin in 1930–2019, 7 surveys (6 with
 species-level data) in the central basin, and 8 surveys (7 with
 species-level data) in the eastern basin (1973–2019). This Lake Erie
 dataset represents the most extensive temporal dataset of benthic
 invertebrates available for any of the Laurentian Great Lakes. Benthic
 samples were collected using Ponar or Shipek bottom dredges and taxa
 densities were calculated as individuals per m2 using the area of the
 dredge. Density data are provided for taxa in the Annelida, Arthropoda,
 Mollusca, Cnidaria, Nemertea, and Platyhelminthes phyla. Current taxonomy
 was used for most groups, but in a few cases, older taxonomic names were
 used for consistency with historical data. Analysis of this dataset
 indicated that eutrophication, water quality improvement, and dreissenid
 introduction were the major drivers of changes in the benthic community in
 the western basin, while hypoxia was a major factor in the central basin,
 and dreissenid introduction was most important in the eastern basin. The
 previously diverse benthic community of the western basin has changed
 dramatically over 90 years, transitioning from a diverse benthic species
 assemblage indicative of good water quality in the 1930s to a one of low-
 diversity assemblage dominated by oligochaetes and other
 pollution-tolerant species in the 1960s, followed by recovery in the early
 2000s to a state similar to that reported in 1930. In contrast, the
 central basin benthic community has over the past 60 years been
 consistently dominated by low oxygen-tolerant taxa, signifying the
 persistence of hypoxia. The eastern basin community changed dramatically
 in recent decades, with the disappearance of Diporeia after the
 introduction of Dreissena in the 1990s and more recent declines in
 oligochaetes, amphipods, gastropods, sphaeriid clams, and leeches.
 Considering the rarity of high taxonomic resolution long-term benthic data
 for lake ecosystems, this data set could be useful to explore broader
 aspects of ecological theory, including effects of eutrophication,
 hypoxia, invasive species, and other factors on community organization,
 phylogenetic and functional diversity, and spatial and temporal scales of
 variation in community structure. In addition, the data set could be
 useful for studies on individual species including abundance and
 distribution, species co-occurrence, and how the patterns of dominance and
 rarity change over space and time. Use of this data set for academic or
 educational purposes is encouraged. In doing so, we kindly request the
 data source be properly cited using the title of this dataset, the names
 of the authors, the year of publication, and the link to Dryad. 
description: Lake Erie (surface area 25,690 km<sup>2</sup>) is one
 of five Laurentian Great Lakes of North America centered at 42°15’N and
 81°15’W. It is bounded on the north by the Canadian province of Ontario,
 and on the south, west, and east by the U.S.A. states of Michigan, Ohio,
 Pennsylvania, and New York (moving west to east). The Canadian and the
 U.S. water boundaries meet in the middle of the lake.
 Benthic habitats where samples were collected ranged from depths
 2 to 63.5 m. All benthic invertebrate data were collected during surveys
 conducted in the summer and fall months between 1930 and 2019. Historical
 basin-wide surveys in Lake Erie varied in sample design, number of
 stations sampled per year, sampling gear (Ekman, Petersen,
 Franklin-Anderson, Shipek, and Ponar grabs), the mesh size of the sieve
 used to wash sediments (180 – 760 µm), and the numbers of surveys per year
 (Karatayev et al., 2022, Table 1). The level of taxonomic identification
 and taxa reported also varied among surveys from reporting only
 Oligochaeta and <em>Hexagenia</em> to reporting all species
 collected (Karatayev et al., 2022, Table 1). The weight of benthic
 invertebrates was measured only in a few surveys and different methods and
 units were used to report biomass, including volume (wet ml/sample) in
 1962 – 1965 (Barton, 1988), dry weight in 1978, (Dermott, 1994), and wet
 weight in 2014 and 2019 (Burlakova et al., 2017; Karatayev et al., 2021).
 To reconstruct the benthic wet biomass for all years except 2014 and 2019,
 we multiplied the density of the major taxa (Oligochaeta, Chironomidae,
 Sphaeriidae <em>Dreissena polymorph</em> and <em>D. r.
 bugensis</em>, and <em>Hexagenia</em>) by their
 individual wet weights. Individual wet weights were estimated separately
 for each taxon and each basin by dividing the taxon's average biomass
 for 2019 by their average density (Hrycik et al. in
 preparation).  <em>Western
 basin</em> A total of 18 benthic surveys were
 conducted in the western basin of Lake Erie between 1929 and 2019
 (Karatayev et al., 2022). These studies varied in the number of stations
 sampled (8 – 63), number of sampling events (1 – 24 samplings), and
 duration (from a few days to three years). 1929 – 1930.
 The 1929 – 1930 studies (Wright 1955) were conducted to assess the status
 of benthic and water resources of western Lake Erie. The 1930 study was
 one of the first and most extensive benthic studies conducted in the Great
 Lakes in the early 20th century (Schloesser et al. 2017). In 1929, benthic
 invertebrates were sampled from 14 stations only, using an Ekman dredge.
 In 1930 a more extensive survey was conducted that sampled 80 stations
 using a Petersen dredge (Wright 1955). In addition, the 1929 study was
 less consistent as different numbers of replicate samples were obtained at
 individual stations and sampling periods, thus we excluded the 1929 survey
 from our analysis. <strong>Table
 1</strong>. Lake-wide (or basin-wide) benthic surveys conducted in
 Lake Erie between 1929 – 2019. Surveys marked with shading were excluded
 from analysis due to small sample sizes, incompatible methods, or
 unavailable data. Sampling Date Number of stations 
 Grab sampler type Mesh size, µm Taxonomic resolution 
 Study 
 
 <strong>Western Basin</strong> 
 
      
 
     
 
 1929, June-September 
 14(13)<sup>a</sup> Ekman
 
 500 Groups (genera for selected
 taxa) Wright 1955 
 1930, June-September*
 
 80(67)<sup>a</sup> 
 Petersen 500 Groups (genera
 for selected taxa) Wright 1955 
 1961, May-June* 
 
 40 Petersen 600
 
 Groups (species for selected taxa) Carr and
 Hiltunen 1965 1963-1965 (24
 samplings) 11 
 Franklin-Anderson 500-600
 
 Groups, genera, species Barton
 1988 1967,
 April-August 42<sup>b</sup>
 
 Ponar 650 
 Species Veal and Osmond 1968
 1970, July-August 
 
 12 Ponar 760
 
 Groups Schelske and Roth 1973
 1973, June-October (3
 samplings) 13 Ponar
 
 425 Groups (species for selected
 taxa) Herdendorf 1979; 
 Britt et al. 1980 
 1979,
 October 52 Shipek
 
 153 Species Dermott
 1994 1982,
 June* 40 Ponar
 
 600 Groups, genera 
 Manny and
 Schloesser 1999 1992,
 July-August 9(1)<sup>c</sup>
 
 Ponar 580/180 
 Species Provided by Dermott
 1993, September 
 
 9(2)<sup>c</sup> Ponar
 
 250 Groups, genera 
 Dermott
 and Dow 2008 1993,
 June* 47<sup>d</sup>
 
 Ponar 600 Groups and
 genera for selected taxa Kennedy et al.
 2023 1998,
 April-June 7 Ponar
 
 250 Groups, genera 
 Dermott
 and Dow 2008 2003,
 April-May* 60 Ponar
 
 600 Groups (species for selected
 taxa) Kennedy et al. 2023
 2009, June, September
 
 14 Ponar 500
 
 Groups, genera, species Burlakova et al.
 2014 2010,
 March-April* 31<sup>d</sup>
 
 Ponar 600 
 Species Kennedy et al. 2023
 2014, April, August*
 
 52(1)<sup>c</sup> Ponar
 
 500 Species Schloesser et
 al., 2017; Burlakova et al. 2017 
 
 2019, April-August* 
 26(3)<sup>c</sup> Ponar
 
 500 Species Present
 study 
 <strong>Central Basin</strong> 
 
      
 
     
 
 1963-1965 (24 samplings) 45
 
 Franklin-Anderson 500-600
 
 Groups, species Barton
 1988 1973,
 June-October (3 samplings) 36
 
 Ponar 425 Groups (species
 for selected taxa) Herdendorf 1979;
 Britt et al. 1980 
 1978,
 October 52 Shipek
 
 153 Species Dermott
 1994 1979,
 October 17 Shipek
 
 153 Species Dermott
 1994 1992,
 July-August 22 Ponar
 
 580/180 Species Provided by
 Dermott 1993,
 September 20(4)<sup>c</sup>
 
 Ponar 250 Groups, genera,
 species Dermott and Dow 2008
 1998, April-June 
 
 9 Ponar 250
 
 Groups, genera Dermott and Dow
 2008 2009, June,
 September 18 Ponar
 
 500 Groups, genera, species
 
 Burlakova et al. 2014 
 
 2014, August 3(11)<sup>c</sup>
 
 Ponar 500 
 Species Burlakova et al. 2017
 2019, July-August 
 
 32(17)<sup>c</sup> Ponar
 
 500 Species Present
 study 
 <strong>East Basin</strong> 
 
      
 
     
 
 1963-1965 (24 samplings) 27
 
 Franklin-Anderson 500-600
 
 Groups, species Barton
 1988 1973-1975 only
 average data available (reported as 1974) 26
 
 Ponar 600 Groups
 
 Flint and Merckel 1978; Mullin 1980 
 1976, September 
 
 25 Ponar 600
 
 Species Great Lakes Laboratory 1978
 1978, October 
 
 37 Shipek 153
 
 Species Dermott 1994 
 1992, July-August 
 
 15 Ponar 580/180
 
 Species Provided by Dermott
 1993, September 
 
 10 Ponar 250
 
 Species Dermott and Dow 2008
 1998, April-June 
 
 13(15)<sup>c</sup> Ponar
 
 250 Species Dermott and Dow
 2008 2009, June,
 September 14 Ponar
 
 500 Groups, genera, species
 
 Burlakova et al. 2014 
 
 2014, August 28(15)<sup>c</sup>
 
 Ponar 500 
 Species Burlakova et al. 2017
 2019, July-August 
 
 19(5)<sup>c</sup> Ponar
 
 500 Species Present
 study 
 <sup>a</sup>The number of stations where samples were
 collected successfully (n indicated in parenthesis) and data are
 available. <sup>b</sup>No primary data
 available. <sup>c</sup>The number of
 additional stations where samples were collected for Dreissena only (n
 indicated in parenthesis). <sup>d</sup>No
 data for Dreissena spp. *Surveys that contain the nine
 consistently sampled stations.  
 From the 80 stations sampled in 1930, 13 stations were located in
 areas with hard bottom preventing the collection of quantitative samples,
 and therefore only 67 stations were sampled successfully (Wright 1955).
 Unfortunately, during the 1930 study laboratory analysis methods varied in
 the level of data resolution and the number of taxa reported. While
 Tubificidae and <em>Hexagenia </em>densities were reported
 from all 67 stations, only 11 stations contain information for all taxa, 8
 additional stations also have data for Chironomidae, and Sphaeriidae, and
 29 additional stations have data for Gastropoda, therefore different
 numbers of stations were used to calculate averages for different
 taxa.  1961. A
 number of local studies of bottom fauna in the western basin of Lake Erie
 were conducted in the 1950s (Brown 1953; Britt 1955a, 1955b; Beeton 1961),
 but the next basin-wide survey to be conducted was not until 1961 (Carr
 and Hiltunen 1965; Table 1). Carr and Hiltunen (1965) collected benthic
 samples using a Petersen dredge from 40 stations, including revisiting 33
 stations from Wright’s 1930 study. This study was designed to assess the
 impacts of nutrient pollution primarily from rivers that carried wastes
 away from the population centers of Detroit, Michigan, and Toledo, Ohio.
 As such, the 1961 study was systematic in that it included samples
 primarily from near river mouths (open water sites were also included
 primarily for reference benthos), collected in a short period of time in
 spring before most insects emerge from the water (May – June),
 consistently collected an equal number of replicates at each site (n = 3),
 and followed detailed and consistent laboratory methodology (Schloesser et
 al. 2017). 1963 – 1967.
 In 1963 – 1965, the University of Toronto Great Lakes Institute conducted
 an intensive lake-wide benthic survey comprised of 83 stations annually
 (11 stations in the western basin, 45 stations in the central basin, and
 27 stations in the eastern basin) during 24 cruises (Barton 1988). This
 was the first and the most extensive lake-wide survey in Lake Erie. In
 addition, this was the first basin-wide benthic study in both central and
 eastern basins (Table 1). Unfortunately, this survey has several serious
 sampling limitations including inefficient sampling gear (use of a
 Franklin-Anderson grab as opposed to a Ponar or Petersen grab) and
 problems with the storage and laboratory processing of samples. The
 efficiency of a Franklin-Anderson grab is very low and often collected
 samples that did not contain any benthic organisms (Brinkhurst et al.
 1968; Barton 1988; Barton and Anholt 1997). According to Barton (1988),
 densities averaged by Lake Erie basins in 1962-1965, “were only one-tenth
 to one-third as large as those reported from other studies, most likely
 due to the way the samples were handled prior to preservation”. Moreover,
 20 – 30% of the samples collected from the central and western basins
 during June – August contained no living animals. Because the study was
 conducted during the peak of eutrophication in Lake Erie when extremely
 high oligochaete densities were known to be present, the large
 underestimation of benthic organisms during the 1963 – 1965 surveys is
 obvious. Therefore, we excluded this survey from our analysis. We were not
 able to find data for the 1967 survey mentioned in Veal and Osmond
 (1968). 1970 – 1975.
 In July – August of 1970, 12 stations were sampled by the University of
 Michigan, Ann Arbor using a Ponar grab and washed through 760 µm nylon
 screen (Table 1; Schelske and Roth 1973). This survey was followed by a
 1973 – 1975 study of 13 stations in the western basin and 36 stations in
 the central basins (Britt et al. 1980). From this study, we were able to
 find only 1973 data collected during June – October cruises (Herdendorf
 1979). 1978 – 1979.
 A large, lake-wide benthic survey of 158 stations was conducted in 1978
 –1979 that included 52 stations in the western basin (sampled in 1979
 only), 69 stations in the central basin, and 37 stations in the eastern
 basin (sampled in 1978 only) (Dermott 1994). Unfortunately, this study
 utilized a Shipek grab, and samples were washed through a 153 µm mesh,
 factors which limit the comparability of this survey to other surveys
 (Table 1). 1982 – 2019.
 In June of 1982, benthic samples in the western basin were collected from
 40 stations (Table 1). This survey was performed to assess the progress of
 pollution-abatement programs that were initiated in the early 1970s. J. K.
 Hiltunen (U.S. Fish and Wildlife Service, Great Lakes Fishery Laboratory,
 Ann Arbor, MI) performed both the 1961 and 1982 studies and provided field
 and laboratory guidance to maintain continuity of study comparisons. The
 following surveys were conducted by the U.S. Geological Survey in June
 1993 (47 stations sampled), April – May 2003 (60 stations), March – April
 2010 (31 stations), and April 2014 (31 stations) (Schloesser et al., 2017;
 Kennedy et al. 2023).  Fourteen stations were sampled
 in June – September of 2009 (Burlakova et al., 2014). Based on data
 collected in 2009 and smaller surveys undertaken in 2011 and 2012,
 Burlakova et al. (2014) documented significant changes in benthic
 community composition from 1963 to 2012, with the largest difference found
 between pre- and post-dreissenid invasion communities. While our study
 confirmed these findings, the 2009 survey was largely biased toward the
 shallow (&lt;5 m) zone along the southern shore of the lake exhibiting
 very low benthic density, with several stations having no organisms at all
 (Burlakova et al., 2014). In addition, benthic organisms in this survey
 were live-picked, which also may contribute to underestimation of density,
 compared to picking organisms from preserved samples under the dissection
 scope as was done in other surveys. The combination of all these factors
 led to the unusually low benthic density (e.g., western basin average
 oligochaete density in 2009 was &lt; 10% of the density measured in
 2010). Therefore, we excluded the 2009 survey from the analysis.
 Eighty benthic stations were sampled in July-August of 2014 by
 the SUNY Buffalo State Great Lakes Center (GLC) collecting three replicate
 samples at each station with a Ponar grab. Each sample was placed
 separately into an elutriation device and then washed through a 500-µm
 mesh screen. All retained organisms and sediments were placed into a
 collection jar and preserved with neutral buffered formalin with Rose
 Bengal stain to a final formalin concentration of 5 – 10%. Details are
 described in Schloesser et al. (2017) and Burlakova et al. (2017). Both
 April and summer 2014 samples were processed by the GLC and were combined
 for the long-term analysis. Finally, Lake Erie benthos
 was studied in April 2019 and July-August 2019 by the EPA and GLC. In
 2019, a total of 249 benthic samples were collected at 77 stations,
 including 55 stations sampled aboard R/V <em>Lake
 Guardian</em> in July during the Lake Erie Cooperative Science and
 Monitoring Initiative (CSMI, 2022) benthic survey and 10 Long-Term
 Monitoring (LTM) stations sampled during the U.S. Environmental Protection
 Agency (US EPA) Great Lakes Biology Monitoring Program (GLBMP 2022) summer
 survey in August using a Ponar grab (sampling area 0.0523
 m<sup>2</sup>). Three shallow CSMI stations (973, DO2, ER03)
 in the western basin were sampled by a National Oceanic and Atmospheric
 Administration (NOAA) small vessel in July (Fig. 7). Another 25 CSMI
 stations were sampled aboard the R/V <em>Lake Guardian</em> in
 July only for the assessment of the distribution and population size of
 <em>Dreissena</em>. In addition, 9 stations in the western
 basin were sampled for benthos on April 24, 2019, aboard SUNY Buffalo
 State’s <em>John J. Friedhoff </em>using a petit Ponar
 (sampling area 0.0231 m<sup>2</sup>). These 9 stations (3D,
 8D, 15D, 2L, 6L, 1M, 7M, 8M, and 4R) were sampled consistently over 90
 years (see detail description below). All field operations were conducted
 according to the EPA Standard Operating Procedures for Benthic
 Invertebrate Field Sampling SOP LG406 (US EPA, 2019). Three replicate
 Ponar samples were collected from each station to determine benthic
 species richness, density (number of
 individuals/m<sup>2</sup>) and total wet biomass
 (g/m<sup>2</sup>). All samples collected in 2019 were
 elutriated through a 500 µm mesh sieve and preserved with neutral buffered
 formaldehyde with Rose Bengal stain to a final formalin concentration of 5
 – 10%. Environmental parameters used in this study were collected 1 m
 above the bottom from each of the stations using a Rosette sampler
 equipped with a Seabird CTD, WETlab C‐Star transmissometer measuring beam
 attenuation due to particles (660 nm wavelengths) across a 25 cm
 pathlength, and a Sea-Bird Scientific SBE 43 DO sensor, all deployed from
 the R/V <em>Lake Guardian</em>. Details of
 laboratory sample processing are described in the EPA Standard Operating
 Procedure for Benthic Invertebrate Laboratory Analysis SOP LG407 (US EPA,
 2015) and in Karatayev et al. (2022). All benthic invertebrates were
 picked out of samples under low magnification using a dissecting
 microscope. All <em>Dreissena</em> were identified to species,
 counted, and measured using a digital caliper (0.01 mm). Next, all mussels
 in each replicate were combined into 5 mm size groups and weighed with
 shells to the nearest 0.0001 g after being blotted on absorbent paper.
 Other invertebrates (Amphipoda, Chironomidae, Oligochaeta, Mollusca) were
 identified, counted, and weighed after being blotted dry. Adult
 oligochaetes were identified to species; immatures were taken to the
 lowest taxonomic level possible, usually family, and included in abundance
 estimates. Oligochaete fragments, though counted, were excluded from
 density but used for biomass estimates because they could be weighed but
 not attributed to individuals. Other invertebrates were identified to
 species or genus, when possible. Meiobenthic organisms (e.g., Nematoda,
 Hydracarina, Ostracoda, benthic Cladocera, Copepoda, and Harpacticoida)
 were not recorded in our samples and were excluded from historical data
 analysis, if present.  Data reported by Dermott and Dow
 (2008) from the western basin for 1992, 1993, and 1998 had fewer than 10
 benthic stations per survey and were excluded from all benthos, but 1992
 and 1993 data were included in the analysis of
 <em>Dreissena</em> population dynamics as more stations were
 sampled for <em>Dreissena</em> than for all benthos.
 Therefore, from a total of 18 studies conducted in the western basin of
 Lake Erie over 90 years, we were only able to use data from 11 surveys in
 our analysis. Nevertheless, available data represent the longest and most
 complete dataset of benthic invertebrate time series available for the
 Great Lakes. Another unique aspect of the long-term
 benthic data set collected in the western basin is that while there was a
 large variation in the number of stations and sampling designs over 90
 years, a subset of 9 stations (3D, 8D, 15D, 2L, 6L, 1M, 7M, 8M, and 4R)
 was sampled more consistently by the USGS Great Lakes Science Center
 (formerly the Bureau of Commercial Fisheries and U.S. Fish and Wildlife
 Service) in 1930 (Wright, 1955), 1961 (Carr and Hiltunen, 1965), 1982
 (Manny and Schloesser, 1999), 1993, 2003, and 2010 (Kennedy et al. 2023),
 2014 (Schloesser et al., 2017), and in 2019 by the SUNY Buffalo State
 Great Lakes Center (Karatayev et al. 2022). All of these surveys were
 conducted during springtime, with a similar protocol, using the same mesh
 size (500 – 600 µm), and are likely the most comparable dataset of all the
 surveys. Please note that the 1993 and 2010 studies conducted in on these
 9 stations do not report data on <em>Dreissena</em>.
 <em>Central and eastern basins</em>
 A total of 10 benthic basin-wide surveys were conducted from 1963
 – 2019 in both the central and eastern basins (Table 1). As indicated
 above, data collected by the University of Toronto Great Lakes Institute
 in 1963 – 1965 were excluded from the analysis. In 1973 and 1975, the
 central basin was repeatedly surveyed (4 – 5 times per year) by Britt et
 al. (1980) at 36 stations. Although we were not able to locate primary
 data for 1974 and 1975, data for 1973 were reported by Herdendorf (1979).
 In 1973 – 1976, the eastern basin was surveyed 1 – 3 times per year by
 Flint and Merckel (1978) at 26 stations, however, we were able to locate
 only averaged data for 1973 – 1975 (Mullin, 1980) and another dataset
 reported by species and stations averaged for all surveys conducted in
 1976 (GLC, 1978 report) (Table 1). In 1992 and 1993 respectively, 22 and
 20 stations were sampled in the central basin and 15, 10, and 13 stations
 were sampled in 1992, 1993, and 1998 (Dermott and Dow 2008; Table 1).
 Again, central basin surveys conducted in 1998 had fewer than 10 stations
 sampled (Dermott and Dow, 2008) and were excluded from the analysis of the
 long-term dynamics of benthos (Table 1). Organisms were
 picked out of samples under low magnification using a dissecting
 microscope. Oligochaetes and chironomids were mounted on slides and
 identified under a compound microscope; other organisms were identified
 under a dissecting microscope. Adult oligochaetes were identified to
 species; immatures were taken to the lowest taxonomic level possible,
 usually family, and included in abundance estimates. Fragments were
 excluded from density. Chironomids were identified to the lowest practical
 taxonomic level, usually genus. Other invertebrates were identified to
 species, when possible. Meiobenthic organisms occasionally present in
 samples (e.g., Nematoda, Hydracarina, Ostracoda, benthic Cladocera,
 Copepoda, and Harpacticoida) were not recorded in our samples and were
 excluded from historical data. We report the average density of
 macroinvertebrate (invertebrates retained by a 500 µm sieve) taxa
 (individuals m<sup>-2)</sup> found in all replicate samples
 collected at each station. For the 2019 survey sample, processing is
 described in Standard Operating Procedure for Benthic Invertebrate
 Laboratory Analysis (SOP LG407) (US EPA 2015).  In
 2019, taxonomy followed Kathman and Brinkhurst (1998) (Oligochaeta);
 Holsinger (1972) and Bousfield (1958) (Amphipoda); Epler (2001) and
 Wiederholm (1983) (Chironomidae); and Smith (2001), Merritt et al. (2008),
 and Thorp and Covitch (2001) (for other groups). Details are described in
 Standard Operating Procedure for Benthic Invertebrate Laboratory Analysis
 (SOP LG407, Revision 09, April 2015) (US EPA 2015). Due to inconsistency
 of the level of taxonomic resolution across surveys, species with rare
 occurrences (at 1 to 3 stations total in the whole data set) were pooled
 into higher taxonomic units (e.g., family). We used the Integrated
 Taxonomic Information System (ITIS, https://www.itis.gov/)
 for current taxonomy, but in a few cases, we used taxonomic names listed
 in common identification guides (i.e. species groups) or older names
 consistent with historical data (i.e. Sphaeriidae for family Pisidiidae;
 <em>Mysis relicta; Physa</em>). We
 published an analysis of this dataset and station averages of species
 densities for each year in this article: Karatayev, A. Y., L. E.
 Burlakova, A. R. Hrycik, S. E. Daniel, K. Mehler, E. K. Hinchey, R.
 Dermott, R. Griffiths. 2022. Long-term dynamics of Lake Erie benthos: One
 lake, three distinct communities. Journal of Great Lakes Research. 48(6):
 1599-1617. https://doi.org/10.1016/j.jglr.2022.09.006
description: **Density data for Lake Erie benthic invertebrate assemblages from 1930 to
 2019** This data set for a companion paper by Karatayev et al. (2022)
 provides densities of benthic macroinvertebrates collected from 1930 to
 2019 during surveys in Lake Erie, a Laurentian Great Lake, funded by the
 governments of the United States and Canada to investigate the status and
 changes in benthic community. Of a total of 21 lake- and basin-wide
 benthic surveys conducted in Lake Erie from 1930 to 2019, we were able to
 acquire species-level data for 10 surveys; another 7 surveys only
 identified benthic organisms to higher taxonomic groups. These include
 data from 11 surveys conducted in the western basin of Lake Erie in
 1930–2019, 7 surveys in the central basin, and 8 surveys in the eastern
 basin (1973–2019). This represents the longest dataset of benthic
 invertebrates available for the Great Lakes. Density data are provided for
 taxa in the Annelida, Arthropoda, Mollusca, Cnidaria, Nemertea, and
 Platyhelminthes phyla.   **Description of the data and file structure**
 *File “ErieBenthosTaxaDensity.csv”:* The first row contains the column
 headers. The first 7 columns cover station information and labeled as:
 “Year” (1930, 1961, 1970, 1973, 1974, 1976, 1978, 1979, 1982, 1993, 1998,
 2003, 2010, 2014, 2019), “Basin” (Western, Central, Eastern), “Authors”
 (citation of published paper or report), “Station” (original station
 number), “Depth_m” (in meters), “Latitude_decimal” and “Longitude_decimal”
 (both in decimal degrees). The next 6 columns provide the names of the
 identified species and larger taxonomic groups: Chironomidae;
 Dreissenapolymorpha; Dreissenar.bugensis; Hexagenia; Oligochaeta;
 Sphaeriidae. Please note that in this “ErieBenthosTaxaDensity.csv” file we
 summed densities of all species belong to family Chironomidae; in
 contrast, “ErieBenthosSpeciesDensity.csv” file has entries of Chironomidae
 individuals that were not identified to lower taxonomic level, in addition
 to other species in the family that were identified to tribe or genus.
 Cell numbers in columns 8 – 13 provide the average density
 (individuals/m2) of individuals of each taxon found at each station (as
 average of all replicates collected at this station). Missing data (“NA”)
 include depth and coordinates of some stations in 1930, density of
 Dreissenidae in 1993 and 2003 in the western basin, and densities of
 Sphaeriidae in 1993.   *File “ErieBenthosSpeciesDensity.csv”*: The first
 row contains headers. The first 7 columns cover station information and
 labeled as: “Year” (1976, 1978, 1979, 1992, 1993, 1998, 2003, 2010, 2014,
 2019), “Basin” (Western, Central, Eastern), “Authors” (short citation of
 published paper or report), “Station” (original station number), “Depth_m”
 (in meters), “Latitude_decimal” and “Longitude_decimal” (both in decimal
 degrees). The subsequent 104 columns provide the names of the identified
 macroinvertebrate species or genus in alphabetical order. Cell numbers in
 columns 8 – 111 provide the average density (individuals/m2) of
 individuals of each taxon found at each station (as average of all
 replicates collected at this station).   *File “ErieBenthosTaxonomy.cvs”*:
 The first row contains headers: “Species”, “Genus”, “Family”, “Order”,
 “Class”, and “Phylum”. The following rows contain taxonomic information
 for all benthic macroinvertebrate species (or higher taxa) recorded during
 the Lake Erie 1930 – 2019 surveys. When an organism was not identified to
 species, we used genus name and “sp.”. When more than one species was
 likely in the same genus, we used “spp.” “NA” is used when the specimen
 was not identified to lower taxonomic level.   **Missing value codes**
 *ErieBenthosTaxaDensity.csv*: Missing data (NA) include depths, latitude
 and longitude for 27 stations of the earliest (1930) benthic survey and
 not counted density of Dreissenidae and Sphaeriidae in 1994 and 2003 USGS
 surveys of the western basin (Kennedy et al. 2023, 107 entries).
 *ErieBenthosSpeciesDensity.csv*: missing data (NA) include not counted
 density of Dreissenidae in 2003 USGS surveys of the western basin (Kennedy
 et al. 2023, 60 entries). *ErieBenthosTaxonomy.cvs*: Missing values (NA)
 include absent taxonomic data for organisms not identified to species,
 genus or family levels.   **Sharing/Access information** Analysis of this
 dataset was published in article: Karatayev, A. Y., L. E. Burlakova, A. R.
 Hrycik, S. E. Daniel, K. Mehler, E. K. Hinchey, R. Dermott, R. Griffiths.
 2022. Long-term dynamics of Lake Erie benthos: One lake, three distinct
 communities. Journal of Great Lakes Research. 48(6): 1599-1617.
 Use of this data set
 for academic or educational purposes is encouraged. In doing so, we kindly
 request the data source be properly cited using the title of this dataset,
 the names of the authors, the year of publication, and the link to Dryad.