1 Introduction: Cape Falcon SCUBA Invertebrate Surveys

SCUBA invertebrate sampling targets the density of specific, conspicuous, solitary and mobile invertebrates. Organisms are chosen due to the large abundance, economic value, or ecological value. Only targeted invertebrates greater than 2.5 cm are counted along a 30 x 2 m belt transects across two target depths, 12.5 and 20 meters. No write-ins are allowed.

Our SCUBA invertebrate sampling at Cape Falcon began in 2016, the year harvest restrictions began. Sampling attempts were made in 2015 but did not result in data collection due to poor visibility and challenging weather conditions. Sampling is conducted in the marine reserve and three comparison areas that represent varying levels of fishing pressure (see methods Appendix for additional information about comparison area selection). We conducted two years of sampling that are included in our analysis and report. Note, we were not able to successfully collect data in the comparison areas until 2017.

Table 1: Cape Falcon SCUBA Invertebrate Monitoring Efforts. Sample sizes represent the number of transects per year at each site

Data from SCUBA invertebrate monitoring efforts can be used to explore questions about invertebrate diversity, community composition and density. Questions about diversity and community composition can be used to compare across monitoring tools to understand tool bias or to validate trends seen across tools. This can further help us understand how the invertebrate communities at these sites are similar or different. Data on density enable us to explore changes over time; and whether these changes are similar both inside the reserve and outside in comparison areas. For all data our main focus is exploring trends by site and year.

1.1 Survey Maps

1.1.1 Cape Falcon Marine Reserve

Fig. 14: Map of SCUBA transect locations at Cape Falcon Marine Reserve

1.1.2 Low Fishing Pressure Comparison Area

$Fig. 14: Map of SCUBA transect locations at Low Fishing Pressure Comparison Area$

Fig. 14: Map of SCUBA transect locations at Low Fishing Pressure Comparison Area

1.1.3 Moderate Fishing Pressure Comparison Area

Fig. 14: Map of SCUBA transect locations at Moderate Fishing Pressure Comparison Area

1.1.4 High Fishing Pressure Comparison Area

Fig. 14: Map of SCUBA transect locations at High Fishing Pressure Comparison Area

1.2 Research Questions

Diversity

Does species diversity vary by site or year?

Community Composition

Does community composition vary by site or year?
- If yes, what species drive this variation?

Aggregate Abundance

Does aggregate density vary by site or year?

Focal Species Abundance

Does focal species density vary by site or year?

2 Takeaways

Here we present a summary of our SCUBA invertebrate monitoring results and conclusions. Our conclusions are written with an evaluation of our sampling design, knowledge from prior marine reserves monitoring reports, and future directions of marine reserves monitoring in mind.

2.1 SCUBA Invertebrate Results Summary

Limited sampling indicates estimates of diversity were highly variable. There may be greater species diversity at the Cape Falcon Marine Reserve, but more sampling in comparison areas is needed.

Species diversity indices were greater at the Cape Falcon Marine Reserve compared to the comparison areas; however, sample sizes are low at all comparison areas and estimates of diversity were highly variable. Additional sampling will be needed to more precisely describe invertebrate diversity at Cape Falcon.

Limited sampling indicates no differences in invertebrate community composition between the Cape Falcon Marine Reserve and its associated comparison areas.

There was no structuring of the invertebrate community at the Cape Falcon Marine Reserve and its comparison areas by site or year. However, the data available for this analysis were limited, with fewer than eight replicates available for the three comparison area sites. More sampling is needed to gain greater confidence in similarity among sites.

Four taxonomic groups dominate aggregate density analyses: anemones, barnacles, cucumbers and gastropods.

There are four dominant taxonomic groups when we compare aggregate invertebrate densities - anemones, barnacles, cucumbers and gastropods. There are no clear differences in mean densities of these taxonomic groups among sites. Further sampling is needed to better understand the relative abundances of invertebrates among sites.

Not enough observations of all focal species to detect differences between sites or years

The minimal sampling effort resulted in too few observations for all focal species to detect differences in densities by site or year. Raw data plots hint at some differences in sea urchins between the High Fishing Pressure Comparison Area and the other sites but limited transects per site and year prohibited statistical analyses for this report.

We observed eight Sunflower Sea Stars on a single transect at the Cape Falcon Marine Reserve in 2016.

This observation of the Pycnopodia helianthoides (Sunflower Sea Star) was the only one detected across shallow nearshore reefs at all marine reserve sites and comparison areas post 2016. Sea star wasting disease hit the Oregon Coast in 2014.

2.2 Conclusions

More sampling is needed to fully characterize the Cape Falcon Marine Reserve and its associated comparison areas, but current species lists provide a valuable foundation for these sites.

This is the first report attempting to analyze SCUBA invertebrate data at Cape Falcon and its associated comparison areas. A total of 29 invertebrate species were recorded at the Cape Falcon Marine Reserve, and 17 at the Low Fishing Pressure Comparison Area. The comparison areas with higher fishing pressure (Moderate and High) had fewer documented invertebrate species (21 and 19 respectively) than the Cape Falcon Marine Reserve. This is likely due to the comparatively low sample sizes at comparison area sites. The most abundant invertebrate species in terms of total counts, in the Cape Falcon Marine Reserve were the Leafy Hornmouth Snail (Cerastoma foliatum), and the Giant Plumose Anemone (Metridium farcimen). In the Low Fishing Pressure Comparison Area, the Giant Plumose Anemone and the Leather Sea star (Dermasterias imbricata) were the most abundant invertebrates. The Embedded Sea Cucumber (Cucumaria miniata) and the Giant Plumose Anemone were the most abundant species in the Moderate Fishing Pressure Comparison Area. In the High Fishing Pressure Comparison Area the Purple Sea Urchin (Stronglyocentrotus purpuratus) and the Red Sea Urchin (Mesocentrotus franciscanus) were the most abundant invertebrate species observed. Limited sampling hindered out ability to appropriately characterize these four sites to 1) determine the appropriate nature of the Low Fishing Pressure Comparison Area as a reference site to the marine reserve and 2) document the invertebrate community at all sites. Still, these data provide a first snapshot of the expected list of invertebrate species found at Cape Falcon Marine Reserve and its associated comparison areas.

This sampling provided the first look into sea star and sea urchin trends at Cape Falcon Marine Reserve and its comparison areas.

This report provides a first snapshot of subtidal sea star and sea urchin populations at the northern-most marine reserve site and its comparison areas. Sampling occurred after sea star wasting disease hit the Oregon coast in 2014, so we don’t know the conditions prior to this outbreak. At the aggregate level sea star densities are fairly low across all sites, and while sea urchin densities also appear low at most sites, more sea urchins are found at the High Fishing Pressure Comparison Area. While no statistical analyses were conducted with species level sea star or sea urchin data due to low sample sizes, boxplots show high outliers in sea star abundances at the Cape Falcon Marine Reserve for Pisaster ochraceus and P.helianthoides than at the other sites. We also observe larger interquartile ranges in density of both sea urchin species (Red M.franciscanus, and Purple S.purpuratus) at the High Fishing Pressure Comparison Area than any of the other comparison areas or the Cape Falcon Marine Reserve. Although data are not presented, the species lists of frequency of occurrence and total counts indicate that other sea star species such as D. imbricata, Henricia spp. (Blood Star) and Evasterias troschellii (False Ochre Star) may be common at multiple sites. As more surveys are conducted at these sites it will be interesting to see the relationships develop among these species at the four sites.

A move toward permanent sites or transects is needed to confidently detect future trends in benthic invertebrates with SCUBA surveys.

The first ODFW Ecological Monitoring Report (ODFW 2014) indicated that a minimum of 10 transects are needed to appropriately characterize Oregon’s invertebrate community at each site. We only achieved this sample size at the Cape Falcon Marine Reserve in 2017 (one of two survey years); we did not achieve that sample size at any of the comparison area sites. Limited sample sizes were a result of challenging logistics related to a small boat based survey method in Oregon’s nearshore environment and the challenge to implement monitoring across all marine reserve sites with limited staff. Reducing required sample sizes needed to detect change such as moving to permanant transects, would be beneficial because of these challenges. In order for our program to confidently detect future changes in benthic invertebrates, increased sampling effort or a a move toward permanent sites or transects is needed. Increased sampling effort would likely require an increase to the research budget. With a better understanding of the sea states, visibility and communities of nearshore reefs, we can now select the appropriate permanent locations to focus monitoring efforts, maximizing efficiency in data collection and power to detect change over time.

3 SCUBA Invertebrate Methods

SCUBA invertebrate sampling is conducted in the Cape Falcon Marine Reserve and its associated comparison areas (Low, Moderate, High Fishing Pressure) following PISCO protocols, modified for diving safety in Oregon. Monitoring attempts with SCUBA at Cape Falcon Marine Reserve began in 2016, but resulted in successful data collection only at cape Falcon. Successful data collection of comparison area sites occurred in 2017. Sampling effort targeted 4 days for both spring and fall monitoring, splitting effort between the marine reserve and comparison areas based on ocean conditions.

The purpose of invertebrate sampling is to estimate density of specific, conspicuous, solitary and mobile invertebrates. Organisms are chosen due to the large abundance, economic value, or ecological value. Only targeted invertebrates greater than 2.5 cm are counted along a 30 x 2 m belt transects across two target depths, 12.5 and 20 meters. Sub-sampling occurs within each 10 m segment of the transect for those target species with very high densities (more than 30 individuals per 10 m segment).

No kelp habitat is located in the Cape Falcon Marine Reserve and its associated comparison areas, so dive site locations were randomly generated from available habitat within the targeted depth ranges. Two replicate transects are conducted at each site (see methods Appendix for more details). The unit of replication is at the transect level. Only fully completed, independent transects were included in analysis. For additional details on data collection, please review documentation in the Methods Appendix.

3.1 Diversity

With SCUBA fish surveys, we explored several concepts related to species diversity at a given site:

species richness
unique, common & rare species
diversity indices
diversity through time

3.1.1 Species Richness

To explore species richness at a given site, we reported total observed species richness and also calculated total estimated species richness.

To report total observed species richness at a given site we used incidence data across all sampling years because species turnover at each site (reserve or comparison area) likely occurs on timescales greater than one year.

To calculate estimated species richness, we used a rarefaction and extrapolation technique as described in Hsieh et al 2016, to calculate the effective number of species at each given site. This is the equivalent of calculating Hill diversity = 0. Hill numbers represent a unified standardization method for quantifying and comparing species diversity across multiple sites (Hill 1973), and they represent an intuitive and statistically rigorous alternative to other diversity indices (Chao et al 2014).

We used the same sampling based incidence data as used to document total observed species richness, using the iNext package in R to estimate the asymptote of the species accumulation curve, or the estimated total number of species observable by SCUBA invertebrate surveys at a given site. We also calculated confidence intervals associated with these rarefaction and extrapolation curves and can therefore compare across sites to explore similarity of total estimated species richness for a given sampling effort.

3.1.2 Unique, Common, and Rare Species

Richness alone does not sufficiently describe species biodiversity; additionally uniqueness, rarity and common species also shape and define concepts of biodiversity.

As a first step to exploring unique, rare and common species we generated species count tables. The species count tables include a total count for each species summed for all years by site, and for each year-site combination, as well as mean frequency of occurrence across all samples. This information can tell us both about how frequently the species is observed, as well as its relative abundance.

From the species count tables we identified rare species, as those with a frequency of occurrence of 10% or less (Green and Young 1993), and common species as those with a frequency of occurrence greater than 50% (in other words, the species is observed on one of every two transects). We also identified species that were unique to each marine reserve and comparison area.

3.1.3 Diversity Indices

To gain additional insight into species diversity, we explored several diversity indices by comparing Hill diversity numbers across sites using the iNEXT diversity package in R (Hsieh et al 2016). Hill numbers are parameterized by a diversity order q, which determines the measures’ sensitivity to species relative abundances (Hsieh et al 2016). Hill numbers include the three most widely used species diversity measures; species richness (q = 0), Shannon diversity (q=1) and Simpson diversity (q=2) (Hsieh et al 2016). We used sampling based incidence data with the iNext package in R, to plot rarefaction and extrapolation curves for each Hill number, and compare results across sites. We also calculated 95% confidence intervals associated with these rarefaction & extrapolation curves.

3.1.4 Diversity Through Time

Finally we explored how diversity changed through time. First we plotted each species yearly rarefaction curve against the total cumulative rarefaction curve for all years combined to determine if we had sampled appropriately to compare species diversity from year to year. When our sampling effort was not adequate to compare across years, we pooled data from all years to compare average daily diversity using an anova. This would provide useful information about site diversity for an average sampling day of effort.

All analyses and graphs were created in R v4.0.2, using the iNEXT and Vegan packages.

3.2 Community Composition

We focused our community composition analysis on the question of whether variation in invertebrate community composition was driven by spatial (site) or temporal (year) factors. We did this through both data visualizations with non-multidimensional scaling (nMDS) plots and with statistical tests such as principal coordinates analyses (PCO), multivariate ANOVA tests (PERMANOVA), and dispersion tests (PERMDISP). In addition to site and year, we also explored several species-specific drivers of variation.

To explore variation by site and year, we used invertebrate density data collected on SCUBA invert transects. We used raw data because there were no apparent dominant species and transformations all overly increased the distributions of less common species (Clarke et al. 2006).Densities were calculated from SCUBA invertebrate count data (# inverts/ area) so a similarity-based resemblance matrix was selected. A dummy variable (=1) was added prior to creating the resemblance matrix due to the high prevalence of zeros in the dataset. To visualize the data, we ran a cluster analysis and generated nMDS plots by site and year.

We chose to test for significance in our data by site and depth. We did not test for year because monitoring efforts resulted in only two consecutive years of data and large differences in sampling intensity. We ran a permutational analysis of variance (PERMANOVA), using a mixed model with site as a fixed factor, and depth as a random factor. To explore if any significant results of the PERMANOVA were related to true differences in location or differences in dispersion of samples, we ran a PERMDISP, a distance based test for homogeneity of multivariate dispersions for any factors that were significant in the PERMANOVA (Anderson and Walsh 2013). If a factor was significant in the PERMANOVA but not the PERMDISP, then it can be inferred that the significance is related to a location effect, but not a dispersion effect. If the factor is also significant in the PERMDISP, then significance in the PERMANOVA is related to dispersion, but there may also be a location effect.

Beyond site and depth, we explored species-specific drivers in the variation of invertebrate community structure. We extended our data visualization, by performing a vector analysis of invertebrate species in the community, selecting only the species with > 0.5 Pearson correlations (Hinkle et al. 2003). If more than four species were identified, we only reported on species with a high ( > 0.7) Pearson correlations. We then generated density plots of the identified species to visualize their relationship to site or year. To better understand how these species contributed to variation in the data, we ran a principal coordinates (PCO) analysis, using a Bray-Curtis resemblance matrix, which provides information on the percent of variation explained by each axis.

All analyses and graphs were made in PRIMERe version 7 with PERMANOVA extension.

3.3 Abundance

We explored changes in aggregate and focal species densities by site and year. For aggregate density we summarized data across invertebrate taxonomic groups (similar to Lester et al. 2009) to identify broad scale differences in target invertebrates by site and year. Based on the target list of invertebrates, we had 11 broad taxonomic groupings (Table 2). A list of which species are included in each taxonomic groupings is provided in Table 3.

To determine which taxonomic groups were the most dominant, we summarized means and 95% confidence intervals grouped by site.

For focal species, we explored changes in aggregate and focal species densities by site and year with generalized additive mixed models (GAMMs). We modeled densities using raw count data with the offset of transect area (Maunder and Punt 2004, Zuur 2012) and a negative binomial distribution. GAMMs were chosen to account for non-linear trends in density by year detected in preliminary data exploration (Veneables and Dichmont 2004, Zuur et al. 2009). GAMMs were fitted using the mgcv package in R. Site was treated as a fixed categorical variable, while Year was continuous and smoothed with the thin-plate smoother ‘s()’ (Zuur et al 2009; Zuur 2012), grouped by Site, and k was restricted to 3 knots to prevent over-fitting. Depth-Bin was included as a random effect in the model to account for the sampling design targeting three fixed depths. We limited our modeling exercise to focus on Site and Year as these are two of the primary questions of interest. For species with very low densities across most sites and years, no statistical analyses were conducted as the data violated assumptions of the model framework.

There are eight focal invertebrate species for the OR Marine Reserves Ecological Monitoring Program; seven of which can be found in the shallow water habitats targeted by SCUBA surveys. They include the following:

Ochre Sea Star; Pisaster ochraceus
Sunflower Star; Pycnopodia halianthoides
Purple Sea Urchin; Strongylocentrotus purpuratus
Red Sea Urchin; Mesocentrotus franciscanus
Rock Scallop; Crassadoma gigantea
California Sea Cucumber; Parastichopus californicus
Giant Plumose Anemone; Metridium farcimen

These species were chosen based on their ecological, economic or management importance. For more information please refer to the methods Appendix detailing focal species selection. Additional species beyond focal species were included for analysis when they were identified in community analysis as being an important driver of variation.

All analyses and data plots were created in R v4.0.2, using the mgcv (version 1.8-36), mgcViz and gratia packages. Models were structured in R as follows:

Density = mgcv::gam(Counts ~ Site + s(Year, by = Site, k = 3) + s(Depth-Bin, bs = “re”), offset = log(Transect Area), family = nb)

4 Cape Falcon Results

SCUBA invertebrate sampling efforts at the Cape Falcon Marine Reserve and its comparison areas resulted in two years of data collection, where varying sample sizes were collected per year (Fig. 2). Sampling efforts resulted in more transects completed in the marine reserve than in the comparison areas; with only one year of sampling effort in the comparison areas.

Fig. 2: SCUBA invertebrate monitoring efforts at the Cape Falcon Marine Reserve and its comparison areas resulted in varied sample sizes over the five years of data collection. Sample size is represented in number of transects.

Table 4: Cape Falcon SCUBA Invertebrate Monitoring Efforts

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4.1 Diversity

4.1.1 Species richness

Invertebrate species richness is most similar between the Cape Falcon Marine Reserve and Moderate Fishing Pressure Comparison Area.

Over the two initial years of sampling with SCUBA invertebrate surveys, a total of 29 species (or species groups) were observed in the Cape Falcon Marine Reserve (Table 5). A smaller number of observed species were found in comparison areas (Table 5). For the marine reserve and Moderate Fishing Pressure Comparison Area total estimated richness was higher than observed richness, for the other sites, observed numbers of species richness are similar to the estimated numbers of total species richness (Table 5). The greatest uncertainty in total estimated species was at Cape Falcon Marine Reserve and the Moderate Fishing Pressure Comparison Area.

library(kableExtra)

pna <- data.frame(Area = c("Cape Falcon Marine Reserve",
                           "Low Fishing Pressure Comparison Area",
                           "Moderate Fishing Pressure Comparison Area", 
                           "High Fishing Pressure Comparison Area"),
                  Observed_Richness = c("29","17", "21","19"), 
                  Estimated_Richness = c("37","19", "35", "20"), 
                  LCL = c("30","17", "24", "19"),
                  UCL = c("90", "28", "94", "26"))


  kbl(pna, caption = "Table 5: Observed and estimated invertebrate species richness by site with lower (LCL) and upper (UCL) 95% confidence limits") %>% 
  kableExtra::kable_classic()

Table 5: Observed and estimated invertebrate species richness by site with lower (LCL) and upper (UCL) 95% confidence limits
Area	Observed_Richness	Estimated_Richness	LCL	UCL
Cape Falcon Marine Reserve	29	37	30	90
Low Fishing Pressure Comparison Area	17	19	17	28
Moderate Fishing Pressure Comparison Area	21	35	24	94
High Fishing Pressure Comparison Area	19	20	19	26

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Species rarefaction curves indicate that species richness is greatest at Cape Falcon Marine Reserve compared to any of the comparison areas - even at low sample sizes (Fig. 3). Rarefaction curves appear to level off at Cape Falcon Marine Reserve and the High Fishing Pressure comparison area, suggesting saturation in species richness with this tool at these sites.

Fig. 3: Species rarefaction curves for the Cape Falcon Marine Reserve and its associated comparison areas. Data are pooled across all years of sampling for each site.

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4.1.2 Unique, common and rare species

More unique and rare species found in the Cape Falcon Marine Reserve, but also more sampling

The Cape Falcon Marine Reserve was the only survey site with unique species (n = 5) (Table 6).

Similar numbers of common species were observed between the marine reserve (n=9) and its comparison areas (Low =13, Moderate = 8, High = 11) (Table 7, 10, 13, 16). All commonly observed species found in the Cape Falcon Marine Reserve were observed commonly also in at least one comparison area. Only the Cape Falcon Marine Reserve had any species considered rare (n=4). Note that for comparison areas, these estimates of common and rare species are based on seven SCUBA transects or less.

Many of the other target invertebrate species were not caught frequently resulting in low pooled counts. Not all species were observed each year, for a summary of species counts over the years by site please see tables below.

Unique species, pooled species counts across all years and species counts by individual sampling year are included in the following tables:

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4.1.2.1 Cape Falcon Marine Reserve

Fig. 4: Relative frequency of occurrence of invertebrate species observed at the Cape Falcon Marine Reserve and its associated comparison areas from SCUBA transects. See separate tabs for each site.

4.1.2.2 Low Fishing Pressure Comparison Area

Fig. 4: Relative frequency of invertebrate species observed at the Cape Falcon Marine Reserve and its associated comparison areas from SCUBA transects. See separate tabs for each site.

4.1.2.3 Medium Fishing Pressure Comparison Area

Fig. 4: Relative frequency of invertebrate species observed at the Cape Falcon Marine Reserve and its associated comparison areas from SCUBA transects. See separate tabs for each site.

4.1.2.4 High Fishing Pressure Comparison Area

Fig. 4: Relative frequency of invertebrate species observed at the Cape Falcon Marine Reserve and its associated comparison areas from SCUBA transects. See separate tabs for each site.

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4.1.3 Diversity Indices

Diversity indices were greatest at Cape Falcon Marine Reserve compared to the comparison areas.

Across diversity indices, the effective number of species was appears greatest at Cape Falcon Marine Reserve (Fig. 5). Sample sizes were limited across all comparison areas, and the estimated confidence intervals are broad. Additional sampling will be needed to more accurately describe diversity indices across all comparison areas.

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Fig. 5: Comparing effective number of species (Hill diversity numbers) across the Cape Falcon Marine Reserve and its associated comparison areas fom SCUBA invertebrate transects. Hill numbers include the three most widely used species diversity measures; species richness (q = 0), Shannon diversity (q=1) and Simpson diversity (q=2) (Hsieh et al 2016).

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4.1.4 Diversity through time

We did not get enough samples to evaluate change in species diversity through time at the Cape Falcon Marine Reserve and its associated comparison areas.

Species rarefaction curves by year for each site indicated that we did not sample enough on a yearly basis to compare changes in mean species richness through time (Fig. 6-9).

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For an average day of sampling, invertebrate species diversity does not differ between the Cape Falcon Marine Reserve and its associated comparison areas.

When comparing mean species richness for an average day of sampling, there was no difference between the marine reserve and either of its associated comparison areas (F = 1.493, p > 0.05) (Fig. 10).

Fig. 10: Mean species richness by area with 95% confidence intervals at the Cape Falcon Marine Reserve and its associated comparison areas from SCUBA invertebrate transects.

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4.2 Community Composition

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4.2.1 Variation by Site and Year

There was no clear structuring of invertebrate community composition by site or year at the Cape Falcon Marine Reserve and its comparison areas.

There was no structuring of invertebrate community composition data by site or year at the Cape Falcon Marine Reserve and its comparison areas. (Fig. 11).

Multivariate statistics indicate some differences by depth, but explain little total variation in the data.

PERMANOVA results indicate that depth and the interaction between depth and site (p < 0.05) are significant for invertebrate community composition with SCUBA density data at Cape Falcon Marine Reserve and its comparison areas (Table 18). Estimated variation described by each of the variables and variable interactions was somewhat small. Depth accounted for the highest variability of all the variables/interactions (18%), and depth by site interaction accounted for 19%. The residuals describe over 54% of the variation in the results. Therefore, while these factor/interactions were significant, the variability observed among samples in the nMDS plot indicates that patterns between depth and depth by site interactions are likely weak.

Table 18: PERMANOVA results

PERMDISP results do not indicate differences in dispersion by depth (p > 0.05) (Table 19). This suggests the significance identified in the PERMANOVA is likely because of differences in spatial location among depths, rather than dispersion among depths.

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4.2.1.1 Site

Fig. 11: Results from nMDS plots with SCUBA invertebrate data, demonstrating similarity in invertebrate community composition by site and year at the Cape Falcon Marine Reserve and its comparison areas. See separate tabs for site and year.

4.2.1.2 Year

Fig. 11: Results from nMDS plots for SCUBA invertebrate data, demonstrating similairity in invertebrate community composition by site and year at the Cape Falcon Marine Reserve and its surrounding comparison areas. See separate tabs for site and year

4.2.1.3 Depth

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4.2.2 Species specific drivers of variation

Three invertebrate species drive the majority of variation in community composition data.

We explored species-specific drivers of variation, and found that B. nubilus, M. farcimen and C. miniata were driving the majority of variation in the benthic invertebrate community (Fig. 12). Principal coordinate analysis revealed that ~34% of the variation along the x-axis is explained by B. nubilus and M. farcimen and 16% of variation is explained along the y-axis from C. miniata (Fig. 12). Together the abundance of these three species accounts for ~ 50% of model variability.

4.2.2.1 PCO Vector Overlay

Fig. 12: Results from species correlations and principal coordinate analysis demonstrating that B. nubilus, M. farcimen and C. miniata drive variaiton in community structure at the Cape Falcon Marine Reserve and its comparison areas. Bubble color/size represents species-specific densities in each sample (species density range indicated in legend). See separate tabs for vector overlay and bubble plot.

4.2.2.2 PCO Bubble Plot

Fig. 20: M. farcimen densities at the Cape Falcon Marine Reserve and its associated comparison areas.

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4.5 Additional Species Density

4.5.1 Giant Acorn Barnacle, Balanus nubilus

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4.5.1.1 Density

Too few observations of B. nubilus to detect differences in density by site or year

Despite identification in the community analysis as a significant driver of variation in the invertebrate community, densities of B. nubilus were low across sites and years at the Cape Falcon Marine Reserve and its associated comparison areas, so statistical analyses were not conducted (Fig. 21).

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4.5.1.1.1 B. nubilus Density

Fig. 21: B. nubilus densities at the Cape Falcon Marine Reserve and its associated comparison areas.

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4.5.2 Embedded Sea Cucumber, Cucumaria miniata

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4.5.2.1 Density

Too few observations of C.miniata to detect differences in density by site or year

Despite identification in the community analysis as a significant driver of variation in the invertebrate community, densities of C.miniata were low across sites and years at the Cape Falcon Marine Reserve and its associated comparison areas, so statistical analyses were not conducted (Fig. 22).

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4.5.2.1.1 C. miniata Density

Fig. 22: C. miniata densities at the Cape Falcon Marine Reserve and its associated comparison areas.

5 References

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Hsieh, T. C., Ma, K. H., & Chao, A. (2016). iNEXT: an R package for rarefaction and extrapolation of species diversity (H ill numbers). Methods in Ecology and Evolution, 7(12), 1451-1456.

Legendre P. and Anderson M.J. 1999. Distance-based redundancy analysis: Testing multispecies responses in multifactorial ecological experiments. Ecological Monographs 69(1): 1-24.

Lester, S. E., Halpern, B. S., Grorud-Colvert, K., Lubchenco, J., Ruttenberg, B. I., Gaines, S. D., … & Warner, R. R. (2009). Biological effects within no-take marine reserves: a global synthesis. Marine Ecology Progress Series, 384, 33-46.

Love, M. S., & Yoklavich, M. M. (2006). Deep rock habitats. In The ecology of marine fishes (pp. 253-266). University of California Press.

ODFW (2014). Oregon Marine Reserve Ecological Monitoring Report 2010-2011. Oregon Department of Fish and Wildlife. Marine Resources Program. Newport Oregon. 1-131.

R Core Team (2020). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL: https://www.R-project.org/.

Venables, W. N., & Dichmont, C. M. (2004). GLMs, GAMs and GLMMs: an overview of theory for applications in fisheries research. Fisheries research, 70(2-3), 319-337.

Zuur, A., Ieno, E. N., Walker, N., Saveliev, A. A., & Smith, G. M. (2009). Mixed effects models and extensions in ecology with R. Springer Science & Business Media.

Zuur, A. F. (2012). A beginner’s guide to generalized additive models with R (pp. 1-206). Newburgh, NY, USA: Highland Statistics Limited.

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