Bart Christiaen Jaime Miller

Outline  Background Information  Survey Sites  Questions + Methods  Results  Inferences  Conclusions

Why Care?  Feed on pytoplankton, detritus, epiphytes, microzooplankton  Food source for many post larval and juvenile finfish  Epifaunal communities as bioindicators  Vazquez-Luis et al (2009)  Guerra-Garcia et al (2006)  Sanchez-Moyano et al (2000) reef.eden.net tamug.edu deepseavoyage.research.pdx.edu

CIMAR  Patchy P. oceanica beds  No barrier from wind/wave action  Higher anthropogenic impact

Tabarca  Large meadows of P. oceanica  Natural barriers from wind/wave action  Less anthropogenic impact (MPA)

Through survey techniques: 1 : Is there a difference in the invertebrate community between CIMAR and Tabarca when you look at patches of Posidonia oceanica with similar characteristics (large, equal density, sampling in the center of the patch)? 2:Is there a difference between day-night communities of benthic invertebrates ? Research Questions Possible inferences?

Methods  5 transects per location  10m transects in similar looking parches  Handheld net  Samples in cooler with seawater till processed  Shoot density

Meadow comparison NMeanStdev Tabarca CIMAR Density (shoots/m2) Two-sample T for Tabarca vs CIMAR T-Value = 0.40 P-Value = DF = 18

Invertebrate communities  3 locations (CIMAR day, CIMAR night, Tabarca), 15 samples, benthic epifauna > 0.5 mm  Total count: 911 animals  7 categories: gastropod, amphipod, isopod, mysid, shrimp, crab, fish  Each category divided in 6 length classes (mm): 0-2.5, 2.5-5, 5-10, 10-20, 20-50, 50+ Graphical Representation, “Diversity” Indices, Multidimensional Scaling

Tabarca: more Mysids and Shrimp, higher size classes CIMAR - Tabarca

No difference between CIMAR and Tabarca CIMAR - Tabarca

CIMAR night: higher abundance of amphipods and gastropods, bigger size classes CIMAR day vs. night

CIMAR night: higher abundance of Mysids and Shrimp, bigger size classes

Diversity indices TabarcaCIMAR nightCIMAR day OTU5 +/ / /- 1.8 individuals12.8 +/ / /- 3.4 Shannon index1.5 +/ / /- 0.4 One-way ANOVA: Normality and equal variance test passed P = R-Sq(adj) = 70.30% Tukey test: Cimar night vs. day: P < Cimar night vs. Tabarca: P < Tabarca vs. Cimar: P = 0.482

Temporal Variation - Site MDS plot CIMAR night CIMAR day Tabarca stress: Invert community distinctly different at night

More abundant in CIMAR CIMAR vs. TABARCA what we expected to see

CIMAR vs. TABARCA what we expected to see More abundant in Tabarca

effect of the weather conditions? limited amount of data CIMAR vs. TABARCA No difference? effect is not there?

CIMAR DAY vs. NIGHT diurnal migration to avoid visual predation?

Sampling during the day = severe underestimation of diversity and abundance of invertebrate communities in beds of Posidonia oceanica If you want to study epifauna diversity in seagrass beds: prepare to spend some sleepless nights!

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