Effects of rocky intertidal algal cover on invertebrate diversity at Green’s Point, NB Marissa Hackman Clay Steell Hannah Kienzle Jessica Browne Alanna MacDonald

Pro Plant Cover Plant cover can provide protection from the tide The presence of macroalgae can increase invertebrate colonization (Downes 2000) Plant richness has been noted to increase invertebrate richness (Knops et al. 1989) Some research has shown that canopy algae can host more invertebrate diversity (Bustamante et al. 2014).

Con: Plant cover Plant cover may increase invertebrate abundance rather than richness (Gunnill 1982) In a study examining Fucus vesiculosis, a decrease in biomass affected abundance and biomass not richness (Wikstrom and Kautsky 2007)

Purpose and Hypothesis To investigate the effect of plant cover on invertebrate richness Hypothesis: Increasing plant cover will increase overall invertebrate richness Photo by David Fenwickh

The Algae A. nodosum dominant F. vesiculosis distribution more variable (Thomas, 1994) Fucus vesiculosis Ascophyllum nodosum http://www.aphotomarine.com/images/seaweed/brown_seaweed_bladder_wrack_fucus_vesiculosus_12-07-10_1.jpg http://www.mer-littoral.org/62/photos-600x400/ascophyllum-nodosum-jcj08-600x400.jpg

Notable Invertebrates Littorina spp. Testudinalia Testudinalos Balanus balanus Semibalanus balanoides Buccinum undatum Gammarus oceanicus Asterias forbesi Carcinus maenas Bryozoan spp. Periwinkles, Common Tortoise Limpet, Common Whelk, amphipod, Forbes Sea star, Green Crab, http://upload.wikimedia.org/wikipedia/commons/f/f6/Littorina_scutulata_2881_cropped.jpg, http://www.clarku.edu/departments/biology/biol201/2008/VLocker/website/Images/tectura1.280.jpg, http://www.marlin.ac.uk/imgs/o_IFSmith20110524.jpg, http://www.lightscapes.info/onewithnature/wp-content/uploads/2013/03/Acorn-Barnacle-Semibalanus-balanoides-03.jpg, http://upload.wikimedia.org/wikipedia/commons/thumb/5/5d/Buccinum_undatum.jpg/220px-Buccinum_undatum.jpg, http://www.uri.edu/cels/bio/rishores/images/asteria.jpg, http://www.mikedelaney.org/images/Img31.png, http://nas.er.usgs.gov/taxgroup/bryozoans/images/lacy_crust_bryozoan.jpg, http://upload.wikimedia.org/wikipedia/commons/3/3f/Gammarus_roeselii.jpg

Sampling Area: Greens Point Large, rocky substrate Relatively high wave exposure

Methods - Sampling Two transects with 10 quadrats each Surveyed elevation up beach % cover and type of algae recorded Organisms collected to identify later Species identified next day to determine richness

Methods - Statistical Analysis Multiple regression Independent variables: % cover Fucus % cover Ascophyllum Distance Do these variables predict invertebrate diversity (species richness)?

Results 12 species Primarily gastropods and crustaceans

Results Most likely model incorporates only Fucus % cover has a significant effect on richness (R2=0.21, p=0.043) Ascophyllum cover and distance from shore Not significant predictors in models where they were included Model AIC likelihood Fucus -9.31 0.437062051 Fucus + Distance -7.57 0.183107823 Fucus + Ascophylum -7.383 0.166763256 Null model -6.965 0.135310911 Full model -5.857 0.077755958

Results

Discussion Greater Fucus coverage may increase invertebrate richness Ascophyllum coverage had no relationship with invertebrate richness Reflects the variation found in the literature

Discussion Research has shown that macroalgae coverage is associated with increased faunal diversity In contrast, several studies have reported no relationship

Discussion Plant coverage may provide protection from desiccation or temperature extremes May be able to support more herbivores and hence attract predatory invertebrates These factors may explain trends observed in Fucus

Discussion This relationship may be affected by interaction with other physical factors (i.e. epiphytes, wind exposure) and other plant species Potential influence of structural differences between Fucus and Ascophyllum May explain differences

Discussion: Future Research Measure abundance of each species Using diversity indices rather than solely richness Increased number of samples Taken from various sites will allow a more thorough analysis more accurate description of this relationship

Questions and Comments