Hilary Hamilton, Samantha Scriber, Isla Murphy, Jenna Munden, Katherine Fraser, Joe McSheffery Interactions between Individual Substrate Type and Macrofauna Biodiversity in the Midlittoral Rocky Intertidal

Overview Introduction Research Questions and Hypotheses Materials and Methods Results and Discussion Conclusions

Introduction

Background Information Sediment characteristics reflect the salinity, oxygen content, pore-water content, temperature, food availability, sedimentation rate, substrate consistency, turbidity, and predation found in a particular environment sediment characteristics define what organisms can survive in the environment Biodiversity: describes the sum total variation of life forms in a specific environment.

Previous Studies community structure varies with the type, complexity and heterogeneity of the substrate (Holland & Elmore, 2008). Previous studies have reported that substrate heterogeneity enhances the diversity of macrobenthos species (Wang et al, 2009). preferable environment for settling, breeding, and preying, as well as better shelter, and richer food sources in comparison to other habitats

Rocky Intertidal Zone Interface between marine and terrestrial habitats Substrates typically found in the rocky intertidal zone include bedrock, boulder, cobble, gravel, sand and algae The mixture of substrates changes based on tidal location and other environmental factors such as wave exposure at a particular location.

Gap in Knowledge Details relating to substrate types are often overlooked leading to an oversimplified experimental design Time consuming Complex intertidal conditions

Research Questions Goals - in depth analysis of substrate composition and biodiversity Among heterogeneous substrates, which types of substrate promote the highest level of biodiversity in the rocky shore intertidal zone located off of the Passamaquoddy Bay?

Hypothesis Biodiversity will be highest at sites with algal cover. provides a buffer of external stressors such as heat, desiccation, and wave stress for invertebrates in high densities algae may trap sediment and smother the invertebrates or limit feeding but this effect will be reduced by the high wave action characteristic of the rocky intertidal zone.

Materials and Methods

Materials 1 m2 quadrat 100m Transect Plastic bags to transport specimens Aquarium to store specimens at Hunts Species Identification guide

Methods Sampled at Indian Point, Bar Road, Left and Right of Road at Green’s Point Mid-intertidal zone Parallel with shore. Limiting factors between quadrats.

Methods Sampled 10m intervals. Each quadrat recorded substrate coverage

Substrates Sand/Mud/Silt= Any sediment smaller than a fingernail Algae= Ascophyllum nodosum, Vertebrata lanosa, Fucus vesiculosus Cobble= Stones smaller than your fist, larger than fingernail < x < Rock= Larger than your fist, large enough to move easily Bedrock

Methods Members of group counted organisms and they were recorded Identified in the field Given identifying characteristic and brought back to Huntsman Marine Center Identified at Huntsman Marine Center using identification key, dissecting scope. Recorded in excel

Results and Discussion

Diversity Indices Weighted towards evenness Shannon-Wiener Simpson’s Weighted towards evenness Measures representation of a species throughout a sample Diversity at a minimum at 0 Weighted towards abundance Measures the probability of two organisms being the same species Diversity at a maximum at 0 Both the Shannon-Wiener Index and the Simpson’s Diversity Index are ways to measure a habitat’s diversity with regard to the evenness of species and the abundance of species. However, Simpson’s Diversity is weighted more towards the abundance of species while the Shannon-Wiener Index is weighted more towards the evenness of species. Simpson’s Diversity Index measures the probability that two individuals randomly selected from a population will be the same species. The Shannon-Wiener Index measures whether species are well represented throughout the entire sample. We used both measures of diversity for an extra measure of diversity. One’s not better than the other

Hard-Substrates: Cobble Shannon-Wiener Simpson’s These graphs are an example of the primary method of data manipulation used in our experiment. For all substrate types Shannon-Wiener Index and Simpson’s Diversity were plotted against the percentage of substrate covering a quadrat, in this case it was cobble. Both graphs show a general increase in diversity as the percentage of cobble cover increases and p-values were calculated from a linear regression analysis to tell us whether the slopes of the line were significantly different than 0. P=0.6545 P=0.2206

Significance To determine whether trendlines fit the data for the graphs comparing substrate cover and species diversity, a linear regression test was performed. Other that Shannon-Wiener Index data for bedrock cover, no substrates had a significant trend with increasing or decreasing diversity. Significance of trendline determined by linear regression analysis

Bedrock Significance Significant p-value of 0.0174 for linear analysis with Shannon’s diversity Increasing bedrock cover relates to decreasing biodiversity Significant cover range 10% to 100% Intermediate Disturbance Hypothesis

Habitat Complexity and Biodiversity To look at how the complexity of a habitat affects diversity, diversity was plotted against the number of substrates observed in each quadrat. This was done with each sampling site and repeated with each measure of diversity

Wikstrom & Kautsky (2007) Increased biomass of understory organisms in areas with Fucus compared to areas without Fucus. Since no species were specific to Fucus, this result can be assumed to be due to the characteristic of Fucus being an ecosystem engineer. Habitat amelioration-shading properties, thermal and dessication stress buffering abilities.

Chi2 Test for Biomass Bar Road Indian Point Green’s Point: Right Green’s Point: Left To determine whether substrate has an affect on biomass, a t-test was performed. This was done by comparing the number of species found in each quadrat to the expected values if all were distributed evenly. All sampling sites were determined to have a non random distribution over the transect.

Soft Substrates: Algae Biomass Each transect showed significant difference in the number of animals in each plot than what would be expected by chance. Sampling Site 3 plots with highest algal coverage Observed % of biomass Expected % of biomass Green’s Point Left 68 30 Right 82 50 Indian Point Bar Road 48 Shows effect of substrate? Environment? Could be many factors but will concentrate on substrate. Using plots with the highest % of algal coverage. At green’s point left there was 5 with 100% algal coverage so they all were used. Chi SqUaReD!!!

Species Distribution Indian Point Another way we manipulated the data was by looking at the number of each species found at each sampling site. In the red boxes, you can see the number of barnacles found at Indian Point

Species Distribution Bar Road And again at bar road

Species Distribution Green’s Point: Left But something that we found interesting is that on either side of bar road, there were little

Species Distribution Green’s Point: Right No Barnacles Or no barnacles found

Jenkins, Norton & Hawkins, 1999 Negative interaction between algae and cyprid. Positive interaction between algae and adult. In general Negative interaction: macro algae interacts negatively by reducing access to the substratum, due to reduced flow under the canopy. The sweeping motion of the fronds during submersion enhances this negative effect and functions to destroy or sweep away cyprids. Positive interaction: buffering capacity, thermal and water stress Varying results with specific algae species as well as exposure of the shore

Soft Substrates: Algae Algae and Barnacle interactions Sampling Site Number of Barnacles % of total Algae coverage Green’s Point Left 87 Right 11 63.5 Indian Point 1294 1.3 Bar Road 811 2.53 Clearly there is a relationship between barnacles the substrate algae…algae is appearing to inhibit barnacles.

Soft Substrates: Algae Vertebrata lanosa and Ascophyllum nodosum Hemiparastic, A plant, such as mistletoe, that obtains some nourishment from its host but also photosynthesizes Polysiphonia attaches to the receptacles, air bladders and damaged blades of Ascophyllum This is accomplished by the extensive network of Polysiphonia’s rhizoids (Ciciotte & Thomas, 1997). Polysiphonia lanosa and its host exchange photoassimilates, energy storing compounds created by photosynthesis (Ciciotte & Thomas, 1997). Vertebrata lanosa not acting as a shading algae. In our research, polysiphoina was only found with ascophyllum Polysiphonia does not affect diversity of the ascophyllum environment

Conclusions Although we observed some interactions between substrates and biodiversity Significant findings: Bedrock = significant negative interaction Chi-squared test for heterogeneity of substrate and biomass Simplistic substrate definitions Greater sample sizes could lead to more concrete conclusions

Questions?