Tag: Caitlin Plowman

Differences in the Morphology and Reproduction of Boltenia villosa Across a Latitudinal Gradient

Presenter: Carmen Sanchez-Reddick – Marine Biology

Faculty Mentor(s): Craig Young, Caitlin Plowman

Session: (Virtual) Poster Presentation

While the larval and early juvenile stages of Boltenia villosa are well documented in the literature, little is known about the adults. Early documentation of B. villosa describes a relationship between the body size and the stalk length as individuals with smaller bodies tend to have longer stalks and individuals with larger bodies tend to possess very short stalks. Anecdotal evidence suggests that larger individuals with short stalks make up the populations found in Washington, while Oregon populations consist of smaller individuals with longer stalks. The present study aimed to develop a qualitative understanding of the changes across the latitudinal gradient of Boltenia villosa. This was achieved by using a combination of morphometrics to determine any significant differences between different populations and histology to compare reproductive output. Preliminary results suggest a significant morphological difference between the two populations in body proportions and spine character despite their genetic similarities. Our understanding of the reproductive differences are continuing to be developed. These results indicate the possible existence of a subspecies of Boltenia villosa due to the distinct populations, but more research into each morphotype’s range is needed. This research also provides a broader understanding of how different marine environments can curate specific characteristics to appear in their inhabitants’ populations.

Reduced success of S. purpuratus fertilization under low pH conditions

Presenter(s): Clara Rehmann

Co Presenter(s): Joe Dahlke

Faculty Mentor(s): Lisa Munger & Caitlin Plowman

Poster 59

Session: Sciences

The oceans serve as an important carbon sink, but rising amounts of dissolved carbon are reducing their pH. Projections anticipate a decrease in mean surface pH from 8.07 to 7.67 by 2100, and some regions are already experiencing pH fluctuations with lows below 7.15 units. Studies have demonstrated Strongylocentrotus purpuratus urchins to be evolving in response to acidifying conditions, but successful spawning amongst this species may be inhibited by more acidic seawater. To determine the effect of reduced pH on fertilization success, we simulated spawning by mixing collected gametes in seawater solutions of decreasing pH and assessed eggs for fertilization using a compound microscope. We found that mean percent fertilization decreased significantly from pH 8.06 (M=98%, SD=1.81) to pH 7.00 (M=84%, SD=12.33) seawater; t(8)=-2.52, p=.026. Natural pH fluctuations combined with ocean acidification could bring pH levels below 7.00 in the near future, possibly inhibiting the success of S. purpuratus reproduction. The resultant decline in urchin populations would have negative consequences for the Pacific kelp forests in which this species lives and could disrupt these fragile ecosystems.