June 1, 2018

MIT Sea Grant Ocean Acidification Project Completion Seminar Tuesday June 26th at 10:00 AM

Please join us Tuesday June 26th at MIT Sea Grant for in depth presentations by three MIT Sea Grant funded researchers summarizing the completion of their ocean acidification projects.

Tuesday June 26th
10:00-12:00
NW98-152 MIT Sea Grant Large Conference Room
12 Emily St. Cambridge, MA

The seminar is open to the public. Please pass this announcement along to interested parties. Questions can be sent to KBaltes@mit.edu.

If you are unable to attend in person, the seminar will be streamed live on MIT Sea Grant Youtube.


Quantification of the Contribution of Wastewater Effluent to Coastal Ocean Acidification
Scott Doney and Jennie Rheuban
Woods Hole Oceanographic Institution

The objective of our SeaGrant project is to determine the influence of wastewater treatment facility effluent on coastal acidification in Buzzards Bay. Over the past few decades, estuaries around Buzzards Bay have experienced degrading water quality due to coastal nutrient eutrophication that can also lead to acidification. Our study combines hydrodynamic/plume modeling with a field sampling campaign to characterize the dispersion and biogeochemical impact of wastewater discharge. Note, this project is ongoing and will be completed at the end of the summer.

Impact of ocean acidification on calcification dynamics of commercially important mollusks across critical life stages
Justin B. Ries
Northeastern University

This project aims to investigate the vulnerability of commercially important calcifying marine mollusks to ocean acidification (OA) at various stages of their life history. Specific projects include investigating: (1) impact of OA on calcification rates of limpets (Crepidula fornicata) and eastern oysters (Crassostrea virginica) during juvenile vs. adult stages; (2) impact of OA on shell structure of limpets (Crepidula fornicata), quahogs (Mercenaria mercenaria), soft shell clams (Mya arenaria), bay scallops (Argopecten irradians), sea scallops (Placopecten magellanicus), eastern oysters (C. virginica), and mussels (Mytilus edulis); (3) impacts of OA and warming on dissolution kinetics of mollusk shells; and (4) development of novel approaches to measuring pH and dissolved inorganic carbon of molluscan extrapallial fluid (EPF) for assessing the impact of OA on the carbonate chemistry of the fluid from which mollusks calcify. Initial results suggest that early-life-stage limpets are more vulnerable to OA than during their adult stage, while early-life-stage oysters are more resistant to OA than during their adult stage. Results also show that OA negatively impacts calcification rate and shell microstructure of a range of aragonitic (quahogs, soft-shell clams, limpets) and calcitic (oysters, bay scallops, sea scallops) mollusks, but has no impact on calcification rate or shell microstructure of blue mussels. Controlled dissolution experiments reveal that dissolution rates of mollusk shells will be faster under warmer conditions predicted for the future, and that baseline dissolution of mollusk shells occurs even in seawater conditions that are oversaturated with respect to the abiogenic forms of the aragonite, low-Mg calcite, and/or high-Mg calcite mineral polymorphs that are incorporated into mollusk shells. Finally, novel approaches were developed for measuring pH and DIC in the EPF of bivalve mollusks—an approach that we will utilize in the future to explore mollusks’ surprisingly disparate responses to OA across species and life-stages.


Examining the integrated effects of ocean acidification and warming on shell development, structural integrity, and incidence of epizootic shell disease in the juvenile American lobster, Homarus americanus
San Antonio, C. (presenter), Krick, K., Poynton, H., Tlusty, M., and Hannigan, R.
University of Massachusetts Boston

The American lobster fishery is a significant component of the coastal New England economy and community. Native lobster populations are currently experiencing rapid warming and acidification due to climate change. We are examining these combined effects on shell development in juvenile American lobsters, an inherently stressful life stage due to the energetic demands on rapid growth and associated molting. We hypothesize that increased stress due to warming and acidification will compromise the structural integrity of the juvenile lobster shell leading to deformation, deficient mineral presence, altered gene expression, and leading to a potential increase in incidence and severity of epizootic shell disease. Preliminary data from our pilot experiment suggests that juvenile American lobsters grown under low pH and high temperature conditions show differential gene expression compared with the control treatment. Genes coding for calcification proteins (CASP-2 and CP14), cuticle growth proteins, and chitinase were all upregulated under the multi-stressor conditions. Shell mineralogy was similarly affected with significantly less weight percent of calcium detected through energy dispersive x-ray spectroscopy (EDS) in lobsters grown in the low pH/high temperature treatment, impacting smaller juveniles more severely. Evidence of shell disease lesions and bacterial colonies was detected in some specimens using scanning electron microscopy (SEM), but the duration of the pilot study was insufficient to properly compare lesion appearance and severity between treatments. To more thoroughly and quantitatively evaluate our initial findings, we conducted a 50-day trial growing 15-month-old juvenile lobsters under fully replicated treatment conditions (n=18/treatment) crossing three pH set points (8.0, 7.8, 7.6) with two temperatures (15oC and 20oC) tracking growth, ecdysis, and mortality throughout. We will again sequence RNA from the dermal tissue underlying the carapace to a minimum depth of 10 million reads and align it with our previously created reference transcriptome. We expect to see similar upregulation of key shell formation genes under low pH and high temperature conditions. We will image cross sections of the carapace on the SEM and, using EDS analysis, we will determine the density, distribution and weight percent of key mineral elements (Ca, Mg, P) to compare across treatments. We will perform crystallography on any discretely visible calcite, aragonite and calcium apatite (Ca5(PO4)3(OH)) crystals. We anticipate an interaction effect of pH and temperature on shell mineralogy showing a diminished mineral presence and structural integrity compared to control. We will quantitatively compare percent coverage of shell disease lesions between treatments via SEM and imaging software. Cross sections of lesions will be taken for additional mineralogy analysis to examine structural changes to the shell compounded by disease. We expect to see some disease lesions across all treatments, but severity and spread to be greater in the multi-stressor treatment with associated evidence of decreased mineral density and structural integrity. The results of this intensive experiment can enhance our understanding of shell development in the juvenile American lobster: how it precipitates and distributes mineral polymorphs within the cuticle layers, the role that these minerals have on protection from bacterial and disease intrusion, and how these components together may be affected by pH and temperature stressors associated with climate change. Ultimately, these findings could help guide the management of the American lobster fishery as climate change effects continue to worsen and shell disease becomes more prevalent.