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Effects of a Non-Native Crab on the Restoration of Cordgrass in San Francisco Bay

Julie A. Gonzalez, Gregory M. Ruiz, Andrew L. Chang and Katharyn E. Boyer
Ecological Restoration, March 2024, 42 (1) 28-41; DOI: https://doi.org/10.3368/er.42.1.28

Article Figures & Data

Figures

  • Figure 1.
    Figure 1.

    A depiction of the five experimental treatments.

  • Figure 2.
    Figure 2.

    Bars represent the average decline in stem density (no. stems per m2 plot) from June through August across treatments. Error bars show ± one standard error about the mean. Shades of grey are according to treatment and letters denote significant differences among treatments.

  • Figure 3.
    Figure 3.

    Bar plot shows the average stem density (no. stems per m2 plot) across treatments in August, and error bars represent ± one standard error. Shades of grey represent different treatments. Letters denote significant differences among treatments.

  • Figure 4.
    Figure 4.

    Bars show average (A) number of individuals, (B) species richness, and (C) Shannon-Weiner diversity index for invertebrates processed from one sediment core taken from each treatment plot at the end of the experiment. Individual data points are displayed in addition to the mean. Error bars denote ± one standard error and different letters denote significantly different groups.

  • Figure 5.
    Figure 5.

    Non-metric multidimensional scaling (NMDS) of the Bray-Curtis dissimilarity matrix comparing benthic invertebrate (epifaunal plus infaunal) abundances from cores collected at the end of the experiment in October (Stress = 0.120, stress value <0.2 indicates a good fit of the model). Ellipses and shapes according to treatment. Ellipses represent 95% confidence intervals around the group centroid. Species vectors represent coefficients of variation relative to the discriminant axes.

  • Figure 6.
    Figure 6.

    Bars show mean sediment (A) percent organic matter values (B) percent nitrogen (C) carbon to nitrogen ratio and (D) percent carbon by treatment derived from soil cores taken at the end of the experiment. Individual data points are presented in addition to the mean. Error bars represent ± one standard error.

  • Figure 7.
    Figure 7.

    Boxplots show A) H. oregonesis catch per unit effort (CPUE, crabs/trap/day) and B) C. maenas CPUE at four sites in San Francisco Bay, illustrating the spread and skewness of the data. Diamonds represent the average value. Colored bars represent CPUE in areas with “no Spartina” (white) or “Spartina” (dark grey). Pie charts along the bottom represent the visual estimates of habitat substrate categorized as percent “riprap/rock/brick”, “mud”, and “Spartina” in each area at each site. These substrates are the same for C. maenas and H. oregonensis as traps placed in each habitat had the potential to capture both crab species.

  • Figure 8.
    Figure 8.

    A diagram depicting our findings and potential interactions based on the literature. Dark grey arrows show elements that were assessed by this study and light grey arrows show other potential connections. Solid, large arrows suggest strong support based on our findings and solid, smaller arrows represent some evidence based on our findings. Positive symbols represent positive impacts, negative symbols represent negative impacts, zero symbols represent neutral impacts, and a slash in between symbols represent the potential for both types of impacts.

Tables

  • Table 1.

    Comparison of densities (mean ± standard error) of benthic epifaunal and infaunal taxa, and total amphipods and bivalves, across treatments, grouped by order or roughly equivalent clade. The core (area of 15.7 cm2 by 10 cm deep) was sieved through a 500 μm mesh sieve. Annelids were excluded from analysis due to their poor preservation. Letters in parentheses: (i) for introduced or (n) for native.

    SpeciesNo CageC. maenasH. oregonensisPartial CageFull Cage
    Amphipoda
    Ampithoe valida (i)  1.8 (0.7)  3.4 (2.2)  0.4 (0.4)  3.2 (1.1)  1.5 (1.0)
    Corophiidae spp.  0.1 (0.1)  0.0 (0.0)  0.0 (0.0)  0.0 (0.0)  0.3 (0.3)
    Grandidierella japonica (i)14.5 (2.8)  5.3 (1.6)  6.4 (2.6)11.7 (2.1)18.5 (4.6)
    Monocorophium acherusicum (i)  1.4 (1.1)  0.0 (0.0)  0.0 (0.0)  0.0 (0.0)  0.0 (0.0)
    Monocorophium spp.  1.6 (1.1)  1.7 (1.6)  0.2 (0.2)  1.5 (0.5)  0.8 (0.5)
    Sinocorophium c.f. alienense (i)  2.8 (3.6)  1.1 (2.2)  4.8 (7.0)  4.2 (8.3)  2.3 (1.7)
    Cumacea
    Nippoleucon hinumensis (i)  6.9 (3.3)  1.9 (0.9)  1.0 (0.5)  6.3 (3.5)  7.8 (3.5)
    Bivalvia
    Gemma gemma (i)  3.4 (2.0)  3.4 (1.4)  1.0 (0.6)  2.5 (0.7)  1.0 (0.4)
    Potamocorbula amurensis (i)  3.5 (1.4)  1.1 (0.5)  5.0 (3.0)  1.8 (2.4)  6.3 (1.0)
    Limecola balthica (i)  0.1 (0.1)  0.1 (0.1)  0.0 (0.0)  0.0 (0.0)  0.0 (0.0)
    Isopoda
    Gnorisphaeroma oregonensis (n)  0.0 (0.0)  1.1 (1.1)  0.2 (0.2)  0.7 (0.7)  0.0 (0.0)
    Ostracoda
    Osctracoda spp.  0.5 (0.4)  0.3 (0.2)  0.4 (0.2)  1.0 (0.5)  0.5 (0.5)
    Cephalaspidea
    Haminoea c.f. vesicula (n)  0.4 (0.2)  0.0 (0.0)  0.0 (0.0)  0.0 (0.0)  0.0 (0.0)
    Tanaidacea
    Sinelobus c.f. stanfordi (i)  4.6 (2.9)  0.0 (0.0)  0.2 (0.2)  0.2 (0.2)  0.0 (0.0)
    Total amphipods22.1 (3.4)11.6 (5.3)11.8 (2.3)21.8 (4.1)23.3 (5.8)
    Total bivalves  7.0 (2.9)  4.7 (1.5)  6.0 (3.6)  4.3 (1.5)  7.3 (3.4)
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Effects of a Non-Native Crab on the Restoration of Cordgrass in San Francisco Bay
Julie A. Gonzalez, Gregory M. Ruiz, Andrew L. Chang, Katharyn E. Boyer
Ecological Restoration Mar 2024, 42 (1) 28-41; DOI: 10.3368/er.42.1.28
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