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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 Shannon-Wiener Simpson’s Weighted towards evenness Weighted towards Measures representation of Measures the probability of Diversity at a minimum at Diversity at a maximum at a species throughout a sample 0 abundance two organisms being the same species 0 Hard-Substrates: Cobble Shannon-Wiener Simpson’s 1.2 1.4 1 1 Simpson's Diversity Shannon Weiner Diversity 1.2 0.8 y = -0.0021x + 0.8395 R² = 0.0147 0.6 y = 0.0031x + 0.4823 R² = 0.0922 0.8 0.6 0.4 0.4 0.2 0.2 0 0 0 20 P=0.6545 40 60 Percentage of Cobble Cover 80 100 0 20 P=0.2206 40 60 Percentage of Cobble Cover 80 100 Significance 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 1.6 1.4 Shannon Wiener Diversity 1.2 y = 0.1195x + 0.4252 R² = 0.2169 1 0.8 0.6 0.4 0.2 0 0 0.5 1 1.5 2 2.5 3 Number of Substrates per Quadrat 3.5 4 4.5 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. Chi2 Test for Biomass Bar Road Green’s Point: Right Indian Point Green’s Point: Left 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 Green’s Point Right 82 50 Indian Point 82 30 Bar Road 48 30 Species Distribution Indian Point 1600 1420 Number of Individuals 1400 1200 1089 1000 892 800 538 600 400 200 0 163 34 1 3 5 10 2 9 1 Species 13 1 2 1 Species Distribution Bar Road 500 474 450 400 Number of Individuals 400 337 350 300 250 200 150 117 100 50 16 1 0 Balanus balanus Buccinum undatum Gammarus oceanicus 23 19 Isopoda Littorina littorea Littorina obtusata Mytilus edulis unknown Species Semibalanoides Species Distribution Green’s Point: Left 1000 909 900 Number of Individuals 800 700 600 553 500 400 353 316 300 194 200 100 0 29 160 3 30 1 Species 11 Species Distribution Green’s Point: Right No Barnacles 600 515 Number of Individuals 500 400 306 300 220 200 113 100 51 6 0 6 1 12 Species 10 13 20 1 Jenkins, Norton & Hawkins, 1999 Negative interaction between algae and cyprid. Positive interaction between algae and adult. Soft Substrates: Algae Algae and Barnacle interactions Sampling Site Number of Barnacles % of total Algae coverage Green’s Point Left 0 87 Green’s Point Right 11 63.5 Indian Point 1294 1.3 Bar Road 811 2.53 Soft Substrates: Algae Vertebrata lanosa and Ascophyllum nodosum 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?