Baumann, H., Talmage, S.C., and Gobler, C.J. 2012. <a href="http://dx.doi.org/10.1038/NCLIMATE1291">Reduced early life growth and survival in a fish as a direct response to elevated CO2 levels</a>. Nature Climate Change 2:38-4.

Chambers, RC, Candelmo, AC, Habeck, EA, Poach, ME, Wieczorek, D, Cooper, KR, Greenfield, CE, and Phelan, BA. 2014. Effects of elevated CO2 in the early life stages of summer flounder, Paralichthys dentatus, and potential consequences of ocean acidification. Biogeosciences, 11, 1613-1626, <a href="https://doi.org/10.5194/bg-11-1613-2014">doi:10.5194/bg-11-1613-2014.</a>

Davidson MI, Targett TE, Grecay PA. 2016. Evaluating the effects of diel-cycling hypoxia and pH on growth and survival of juvenile summer flounder Paralichthys dentatus. Marine Ecology Progress Series 556:223-235. <a href="https://doi.org/10.3354/meps11817">https://doi.org/10.3354/meps11817</a>.

Depasquale, E, Baumann, H, and Gobler, CJ. 2015. <a href="http://dx.doi.org/10.3354/meps11142">Variation in early life stage vulnerability among Northwest Atlantic estuarine forage fish to ocean acidification and low oxygen</a>. Marine Ecology Progress Series 523:145-156.

Lifavi DM, Targett TE, Grecay PA. 2017. Effects of diel-cycling hypoxia and acidification on juvenile weakfish Cynoscion regalis growth, survival, and activity. Marine Ecology Progress Series 564:163-174. <a href="https://doi.org/10.3354/meps11966">https://doi.org/10.3354/meps11966</a>.

Malvezzi, AJ, Murray, CM, Feldheim, KA, Dibattista, JD, Garant, D, Gobler, CJ, Chapman, DD, and Baumann, H. 2015. <a href="http://dx.doi.org/10.1111/eva.12248">A quantitative genetic approach to assess the evolutionary potential of a coastal marine fish to ocean acidification</a>. Evolutionary Applications 8:352-362.

Miller, SH, Breitburg, DL, Burrell, RB and Keppel, AG. 2016. Acidification increases sensitivity to hypoxia in important forage fishes. Marine Ecology Progress Series, 549:1-8. <a href="http://dx.doi.org/10.3354/meps11695">http://dx.doi.org/10.3354/meps11695</a>.

Murray, CM, Malvezzi, A, Gobler, CJ, and Baumann, H. 2014. <a href="http://dx.doi.org/10.3354/meps10791">Offspring sensitivity to ocean acidification changes seasonally in a coastal marine fish</a>. Marine Ecology Progress Series 504:1-11.

To date (2023), only 24 fish species of the Mid-Atlantic, including about a dozen of commercial or recreational importance, have been studied for their response and sensitivity to ocean and coastal acidification. Most studies are based on laboratory experimentation where the earliest, most sensitive life-stages of fish (gametes, embryos, larvae, and young juveniles) are exposed to different levels of carbon dioxide (CO2) that are intended to mimic future oceanic and coastal conditions.
This is a new yet very active research front with studies becoming ever more realistic and sophisticated.

Jacob Snyder/Silversides Schooling Above Black Sea Bass

Study advances include:
<ul>
<li>using variable CO2 typical of inshore and estuarine waters</li>
<li>estimating the effects of simultaneously acting environmental stressors, such as low dissolved oxygen (DO), elevated temperatures, and contaminants typical of inshore waters</li>
<li>assessing the degree to which young fish can survive and function normally when exposed to these stressors and evaluating whether existing genetic variation exists that might allow adaptation to future high-CO2 conditions.</li>
</ul>
The kinds of complexities revealed in these studies underscore species differences as well as provide evidence that stocks within a species may differ in their responses to acidification.

Hannes Baumann/Northern Sand Lance

Several laboratory studies have been conducted on summer flounder. After exposure to elevated levels of CO2, researchers found summer flounder egg fertilization rate to be lower and, among those that were successfully fertilized, fewer survived to hatching. For larvae, rates of growth and development were accelerated but larval survival was unaffected. In nature, a consequence of accelerated development would be young juvenile summer flounder arriving in bay waters earlier in the season and at smaller sizes than historically normal.
These altered features in size and timing of early life events could heighten the risks of death due to consumption by predators or prolonged exposure to the cold inshore waters typical of winter in coastal Mid-Atlantic fish nurseries. Older summer flounder juveniles also showed increased mortality when subjected to highly variable CO2 and DO conditions.

The responses of winter flounder to elevated levels of CO2 differ from that reported for summer flounder. Among other findings, winter flounder fertilization rates increased with increasing CO2 to a point, then decreased at the highest CO2 levels (most acidic) tested. The fertilization rates decreased with elevated temperatures. Interestingly, the fertilization rate response of New Jersey winter flounder differed from flounder collected in Massachusetts/Southern Gulf of Maine waters in that Massachusetts fish displayed increased fertilization rates at even the most acidic waters but were more sensitive than New Jersey fish to warmer temperatures.

Juvenile weakfish exposed to short-term (30 day) exposures to constant and fluctuating CO2 and DO levels showed negative effects only at the highest level of variability in water chemistry. They appeared to be robust when faced with current-day and projected future CO2 conditions in nursery habitats.

Forage fish, including Atlantic silverside, inland silverside, and sheepshead minnow, are key players in the Mid-Atlantic food web and face significant risks from elevated CO2 and combined stressors like low dissolved oxygen (DO) and high temperatures. These species typically spawn in the subtidal zones of estuaries, exposing adults and offspring to extreme daily variability in CO2, DO, and summer heat.
High acidification CO2 has led to increased embryo mortality, altered hatching timing and sizes, and reduced larval growth rates. Adults may also face direct mortality from elevated CO2 and low DO, as well as increased predation risk under these combined stressors. Research on parent-offspring relationships reveals that offspring from summer-spawning parents, who experience warmer, more acidic, and lower-oxygen conditions, are more resilient to acidification.
Additionally, offspring resilience varies significantly between families, suggesting potential for these species to adapt to future CO2 conditions.

Winter and summer flounder photos courtesy of NOAA/NEFSC

Finfish (any fish with a fin versus a shell) are a diverse group of fish species essential for marine ecosystems and a vital resource for global fisheries and aquaculture.

Finfish

Batiuk, R. A., Bergstrom, P., Karrh, L., Naylor, M., Wilcox, D., Moore, K. A., Kemp, M., Koch, E., Murray, L., Stevenson, J. C., Bartleson, R., Ailstock, S., Teichberg, M., Carter, V., Rybicki, N. B., Landwehr, J. M., &amp; Gallegos, C. (2000). Chesapeake Bay Submerged Aquatic Vegetation Water Quality and Habitat-Based Requirements and Restoration Targets: A Second Synthesis. <a href="https://d38c6ppuviqmfp.cloudfront.net/content/publications/cbp_13051_13053.pdf">https://d38c6ppuviqmfp.cloudfront.net/content/publications/cbp_13051_13053.pdf</a>

Invers, O., Zimmerman, R. C., Alberte, R. S., Pérez, M., &amp; Romero, J. (2001). Inorganic carbon sources for seagrass photosynthesis: An experimental evaluation of bicarbonate use in species inhabiting temperate waters. Journal of Experimental Marine Biology and Ecology, 265(2), 203–217. <a href="https://doi.org/10.1016/S0022-0981(01)00332-X">https://doi.org/10.1016/S0022-0981(01)00332-X</a>

Lloyd, N. D. H., Canvin, D. T., &amp; Bristow, J. M. (1977). Photosynthesis and photorespiration in submerged aquatic vascular plants. Canadian Journal of Botany, 55(24), 3001–3005. <a href="https://doi.org/10.1139/b77-337">https://doi.org/10.1139/b77-337</a>

Moore, K. A., &amp; Jarvis, J. C. (2008). Environmental Factors Affecting Recent Summertime Eelgrass Diebacks in the Lower Chesapeake Bay: Implications for Long-term Persistence. Journal of Coastal Research, 10055, 135–147. <a href="https://doi.org/10.2112/SI55-014">https://doi.org/10.2112/SI55-014</a>

Orth, R. J., Luckenbach, M. L., Marion, S. R., Moore, K. A., &amp; Wilcox, D. J. (2006). Seagrass recovery in the Delmarva Coastal Bays, USA. Aquatic Botany, 84(1), 26–36. <a href="https://doi.org/10.1016/j.aquabot.2005.07.007">https://doi.org/10.1016/j.aquabot.2005.07.007</a>

Zimmerman, R. C., Hill, V. J., &amp; Gallegos, C. L. (2015). Predicting effects of ocean warming, acidification, and water quality on Chesapeake region eelgrass. Limnology and Oceanography, 60(5), 1781–1804. <a href="https://doi.org/10.1002/lno.10139">https://doi.org/10.1002/lno.10139</a>

Zimmerman, R. C., Kohrs, D. G., Steller, D. L., &amp; Alberte, R. S. (1997). Impacts of CO2 Enrichment on Productivity and Light Requirements of Eelgrass. Plant Physiology, 115(2), 599–607. <a href="https://doi.org/10.1104/pp.115.2.599">https://doi.org/10.1104/pp.115.2.599</a>

Zimmerman, R., Hill, V., Jinuntuya, M., Celebi, B., Ruble, D., Smith, M., Cedeno, T., &amp; Swingle, W. (2017). Experimental impacts of climate warming and ocean carbonation on eelgrass Zostera marina. Marine Ecology Progress Series, 566, 1–15. <a href="https://doi.org/10.3354/meps12051">https://doi.org/10.3354/meps12051</a>

The extensive system of bays, barrier islands, and shallow coastal lagoons of the Mid-Atlantic region provide important habitat for both fresh and saltwater vascular plants, collectively known as submerged aquatic vegetation (SAV).
SAV are shallow-water ecosystem engineers that modify their physical and chemical environment as they grow. In doing so, they provide many ecosystem services:
<ul>
<li>Act as essential nursery habitat and feeding grounds for juvenile marine species</li>
<li>Stabilize and allow sediments accumulation</li>
<li>Reduce the impacts of waves and shoreline erosion</li>
<li>Remove excess nutrients and CO2 through biological processes</li>
<li>Oxygenate the surrounding water as they photosynthesize</li>
</ul>

Despite historic abundance, SAV populations in the Mid-Atlantic have been adversely affected by deteriorating water quality associated with human activity. Declining water quality, combined with disease outbreaks and damage from hurricanes in the early 20th century, have left the SAV area at a fraction of its historic range in the Mid-Atlantic. Beyond the Mid-Atlantic, SAV are in decline globally, facing ongoing threats from coastal development, dredging, pollution, and climate change.

While SAV losses have been severe, many Mid-Atlantic states are committed to protecting and expanding current SAV habitat. Efforts to control nutrient and sediment loading from the land have led to improved water quality conditions in many areas, aiding in the recovery of SAV beds.
On the seaside of Virginia’s Eastern Shore, restoration efforts have resulted in the growth of over 7,000 acres of eelgrass (seagrass species). While progress has been made,, concerns remain for the future of SAV in the Mid-Atlantic as CO2 induced climate and water warming may be particularly stressful for heat-intolerant species such as eelgrass.

Because aquatic plants require CO2 to perform photosynthesis, future increases in CO2 could improve growth among SAV species. In fact, present day CO2 limits photosynthetic rates of most SAV species, including wild celery, widgeon grass, and eelgrass.
Consequently, the negative effects of climate warming induced by elevated CO2 may be at least partially offset in these species by increased photosynthetic rates in an acidified coastal environment, as demonstrated by recent theoretical and experimental efforts.

SAV, comprising attached macroalgae and seagrass species, support coastal ecosystems by providing habitat, improving water quality, and buffering against climate change impacts.

Submerged Aquatic Vegetation (SAV)

Baumann, H. (2019). Experimental assessments of marine species sensitivities to ocean acidification and co-stressors: How far have we come? Canadian Journal of Zoology, 97(5), 399–408. <a href="https://doi.org/10.1139/cjz-2018-0198">https://doi.org/10.1139/cjz-2018-0198</a>

Cai, W.-J., Feely, R. A., Testa, J. M., Li, M., Evans, W., Alin, S. R., Xu, Y.-Y., Pelletier, G., Ahmed, A., Greeley, D. J., Newton, J. A., &amp; Bednaršek, N. (2021). Natural and Anthropogenic Drivers of Acidification in Large Estuaries. Annual Review of Marine Science, 13(1), 23–55. <a href="https://doi.org/10.1146/annurev-marine-010419-011004">https://doi.org/10.1146/annurev-marine-010419-011004</a>

Doney, S. C., Busch, D. S., Cooley, S. R., &amp; Kroeker, K. J. (2020). The Impacts of Ocean Acidification on Marine Ecosystems and Reliant Human Communities. Annual Review of Environment and Resources, 45(1), 83–112. https://doi.org/10.1146/annurev-environ-012320-083019

Glaspie, C. N., Longmire, K., &amp; Seitz, R. D. (2017). Acidification alters predator-prey interactions of blue crab Callinectes sapidus and soft-shell clam Mya arenaria. Journal of Experimental Marine Biology and Ecology, 489, 58–65. <a href="https://doi.org/10.1016/j.jembe.2016.11.010">https://doi.org/10.1016/j.jembe.2016.11.010</a>

Guinotte, J. M., &amp; Fabry, V. J. (2008). Ocean Acidification and Its Potential Effects on Marine Ecosystems. Annals of the New York Academy of Sciences, 1134(1), 320–342. <a href="https://doi.org/10.1196/annals.1439.013">https://doi.org/10.1196/annals.1439.013</a>

Hoegh-Guldberg, O., Poloczanska, E. S., Skirving, W., &amp; Dove, S. (2017). Coral Reef Ecosystems under Climate Change and Ocean Acidification. Frontiers in Marine Science, 4, 158. <a href="https://doi.org/10.3389/fmars.2017.00158">https://doi.org/10.3389/fmars.2017.00158</a>

Jin, P., Hutchins, D. A., &amp; Gao, K. (2020). The Impacts of Ocean Acidification on Marine Food Quality and Its Potential Food Chain Consequences. Frontiers in Marine Science, 7, 543979. <a href="https://doi.org/10.3389/fmars.2020.543979">https://doi.org/10.3389/fmars.2020.543979</a>

Marshall, K. N., Kaplan, I. C., Hodgson, E. E., Hermann, A., Busch, D. S., McElhany, P., Essington, T. E., Harvey, C. J., &amp; Fulton, E. A. (2017). Risks of ocean acidification in the California Current food web and fisheries: Ecosystem model projections. Global Change Biology, 23(4), 1525–1539. <a href="https://doi.org/10.1111/gcb.13594">https://doi.org/10.1111/gcb.13594</a>

Ricart, A. M., Ward, M., Hill, T. M., Sanford, E., Kroeker, K. J., Takeshita, Y., Merolla, S., Shukla, P., Ninokawa, A. T., Elsmore, K., &amp; Gaylord, B. (2021). Coast‐wide evidence of low pH amelioration by seagrass ecosystems. Global Change Biology, 27(11), 2580–2591. <a href="https://doi.org/10.1111/gcb.15594">https://doi.org/10.1111/gcb.15594</a>

Saba, G. K., Goldsmith, K. A., Cooley, S. R., Grosse, D., Meseck, S. L., Miller, A. W., Phelan, B., Poach, M., Rheault, R., St.Laurent, K., Testa, J. M., Weis, J. S., &amp; Zimmerman, R. (2019). Recommended priorities for research on ecological impacts of ocean and coastal acidification in the U.S. Mid-Atlantic. Estuarine, Coastal and Shelf Science, 225, 106188. <a href="https://doi.org/10.1016/j.ecss.2019.04.022">https://doi.org/10.1016/j.ecss.2019.04.022</a>

Smithsonian Environmental Research Center, Breitberg, D., Salisbury, J., Bernhard, J., Cai, W.-J., Dupont, S., Doney, S., Kroeker, K., Levin, L., Long, W. C., Milke, L., Miller, S., Phelan, B., Passow, U., Seibel, B., Todgham, A., &amp; Tarrant, A. (2015). And on Top of All That… Coping with Ocean Acidification in the Midst of Many Stressors. Oceanography, 25(2), 48–61. <a href="https://doi.org/10.5670/oceanog.2015.31">https://doi.org/10.5670/oceanog.2015.31</a>

Stevens, A., &amp; Gobler, C. (2018). Interactive effects of acidification, hypoxia, and thermal stress on growth, respiration, and survival of four North Atlantic bivalves. Marine Ecology Progress Series, 604, 143–161. <a href="https://doi.org/10.3354/meps12725">https://doi.org/10.3354/meps12725</a>

Waldbusser, G. G., &amp; Salisbury, J. E. (2014). Ocean Acidification in the Coastal Zone from an Organism’s Perspective: Multiple System Parameters, Frequency Domains, and Habitats. Annual Review of Marine Science, 6(1), 221–247. <a href="https://doi.org/10.1146/annurev-marine-121211-172238">https://doi.org/10.1146/annurev-marine-121211-172238</a>

An ecosystem comprises a community of living things, their non-living environment, and the interactions that link species to one another and to their surroundings. Acidification, among other stressors, such as increasing ocean temperatures, harmful algal bloom occurrences, and sea level rise, will affect individual species and the ecosystems they inhabit in diverse ways. Understanding the influence of acidification on entire ecosystems is difficult due to the complexity of the water chemistry, co-occurring biological processes, and the complexity of marine ecosystems themselves.

When acidification impacts one species, whether that’s in a positive or negative way, it can cause a ripple effect that alters ecosystem dynamics in general.
For example:
<ul>
<li>Changes in species abundance or behavior can alter food webs and predator/prey dynamics.</li>
<li>Loss of habitat-forming species, like corals, can leave marine life without shelter or nursery habitat.</li>
<li>Some species can alter their abiotic environment, to the benefit (or detriment) of other species. For example, faster growth by seagrasses due to elevated CO2 may theoretically help to locally increase pH, which can benefit the species that live in the grasses.</li>
</ul>

The severity of ocean acidification, and the impact it has on species, varies based on local and regional environmental conditions. Because of this, organisms living in vastly different ecosystems, like estuaries versus the open ocean, experience different pH “weather”. In contrast to the open ocean, the coastal ocean regularly experiences large fluctuations in pH on timescales ranging from hours (tides) to years (changing climate conditions).
pH &#8220;weather&#8221; events are influenced by:
<ul>
<li>Precipitation</li>
<li>Nutrient runoff &amp; eutrophication due to storm water runoff and seasonal patterns</li>
<li>Day-night cycles of biological activity (respiration at night produces CO2 while photosynthesis during the day consumes CO2)</li>
<li>Oceanic events like upwelling that could be caused by changing wind direction and storms</li>
</ul>

Oftentimes, acidification is not the only stressor marine species are facing. When considering temperatures, eutrophication, oxygen availability, and more, the ultimate impact of acidification on marine life can change; sometimes the abiotic environment exacerbates acidification effects or in other cases buffers against them. Careful and extensive experiments are necessary to understand how low pH interacts with other environmental variables for different species.

Many acidification experiments to date have been performed with only a single species in isolation. However, ecosystems are a complex network of species that interact via food webs, symbiotic relationships, and a myriad of other mechanisms. More and more, experts are working on understanding the intricacies of ecosystem response to acidification.

Ecosystems are highly complex webs of species that mix in space and time, creating intricate relationships that can be difficult or complex to study.

Ecosystems

Cooper, HL, Potts, DC, Paytan, A. 2016. Metabolic responses of the North Pacific krill, Euphausia pacifica, to short- and long-term pCO2 exposure. Marine Biology 163:207. doi: <a href="https://link.springer.com/article/10.1007/s00227-016-2982-z">10.1007/s00227-016-2982.</a>

Cooper, HL, Potts, DC, Paytan, A. 2017. Effects of elevated pCO2 on the survival, growth, and moulting of the Pacific krill species Euphausia pacifica. ICES Journal of Marine Science 74: 1005-1012. doi: <a href="http://dx.doi.org/10.1093/icesjms/fsw021">10.1093/icesjms/fsw021</a>.

Cripps, G, Lindeque, P, Flynn, KJ. 2014. Have we been underestimating the effects of ocean acidification in zooplankton? Global Change Biology 20: 3377-3385. doi: <a href="http://onlinelibrary.wiley.com/doi/10.1111/gcb.12582/abstract">10.1111/gcb.12582</a>.

Cripps, G, Flynn, KJ, Lindeque, PK, Dam, HG. 2016. Ocean Acidification Affects the Phyto-Zoo Plankton Trophic Transfer Efficiency, PLoS ONE 11(4): <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0151739">e0151739</a>.

Garzke, J, Hansen, T, Ismar, SMH, Sommer, U, Ross, P. 2016. Combined Effects of Ocean Warming and Acidification on Copepod Abundance, Body Size and Fatty Acid Content, PLoS ONE 11(5): <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0155952">e0155952</a>.

Kawaguchi, S, Kurihara, H, King, R, Hale, L, Berli, T, and others. 2010. Will krill fare well under Southern Ocean acidification? Biology Letters 7: 288-291. doi:<a href="http://rsbl.royalsocietypublishing.org/content/7/2/288">10.1098/rsbl.2010.0777</a>.

Kawaguchi, S, Ishida, A, King, R, Raymond, B, Waller, N, and others. 2013. Risk maps for Antarctic krill under projected Southern Ocean acidification. Nature Climate Change 3: 843–847. doi:<a href="http://www.nature.com/nclimate/journal/v3/n9/full/nclimate1937.html">10.1038/nclimate1937</a>.

Kurihara, H. 2008. Effects of CO2-driven ocean acidification on the early developmental stages of invertebrates. Marine Ecology Progress Series 373: 275-284. doi:<a href="http://dx.doi.org/10.3354/meps07802">10.3354/meps07802</a>.

Maas, AE, Elder, LE, Dierssen, HM, Seibel, BA. 2011. The metabolic response of Antarctic pteropods (Mollusca: Gastropoda) to regional productivity: implications for biogeochemical cycles. Marine Ecology Progress Series 441: 129-131. doi: <a href="http://www.int-res.com/articles/meps2011/441/m441p129.pdf">10.3354/meps09358</a>.

Rossoll, D, Bermúdez, R, Hauss, H, Schulz, KG, Riebesell, U, and others. 2012. Ocean Acidification-Induced Food Quality Deterioration Constrains Trophic Transfer. PLoS ONE 7(4): <a href="https://doi.org/10.1371/journal.pone.0034737">e34737</a>.

Saba, GK, Schofield, O, Torres, JJ, Ombres, EH, Steinberg, DK. 2012. Increased feeding and nutrient excretion of adult Antarctic krill, Euphausia superba, exposed to enhanced carbon dioxide (CO2). PLoS ONE 7: <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0052224">e0052224</a>.

Seibel, BA, Maas, AE, Dierssen, HM. 2012. Energetic plasticity underlies a variable response to ocean acidification in the pteropod, Limacina helicina antarctica. PLoS ONE 7(4): <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030464">e30464</a>.

Zhang, D, Li, S, Wang, G, Guo, D. 2011. Impacts of CO2-driven seawater acidification on survival, egg production rate and hatching success of four marine copepods. Acta Oceanologica Sinica 30: 86-94. doi:<a href="https://link.springer.com/article/10.1007/s13131-011-0165-9">10.1007/s13131-011-0165-9</a>.

Zooplankton hold a key position in aquatic food webs. They feed on phytoplankton, bacteria, and other zooplankton, and are a major food source for fish, seabirds, and baleen whales. The zooplankton are a diverse group of animals, some of which form calcium carbonate structures (foraminifera, pteropods, and heteropods). Thus, the zooplankton response to acidification is variable.

Direct responses to acidification can include reduced calcification rates and disturbance to acid-base (metabolic) physiology, which can affect other bodily functions. Pteropods, with thin snail-like shells, have been shown to be highly sensitive to decreases in ocean pH causing shell dissolution.
<img loading="lazy" decoding="async" class="alignnone wp-image-4930 size-full" src="https://macancms.3lanemarketing.com/wp-content/uploads/2025/01/phytoplankton.jpg" alt="" width="512" height="153" srcset="https://macancms.3lanemarketing.com/wp-content/uploads/2025/01/phytoplankton.jpg 512w, https://macancms.3lanemarketing.com/wp-content/uploads/2025/01/phytoplankton-300x90.jpg 300w" sizes="auto, (max-width: 512px) 100vw, 512px" />
Indirect effects, while more difficult to measure, include changes to the abundance, composition, and quality of their food source (phytoplankton), which can significantly impact zooplankton metabolic function.

Adult non-calcifying zooplankton are thought to be more tolerant of acidification, but negative effects tend to be amplified in their younger life stages. This has been demonstrated with reduced survival and hatching success and irregular larval development at early developmental stages in several zooplankton groups, including copepods and krill. Krill are an important food source for many marine mammals.
Both direct and indirect responses to acidification can impact zooplankton development, growth, reproduction, and overall population.

Due to variable responses of different species to acidification and differential effects to various zooplankton life stages, it is difficult to predict how natural zooplankton communities will respond to acidification and how those changes will reverberate through food webs.
Furthermore, other stressors including changes in water temperature, food source, and levels of dissolved oxygen can also affect zooplankton abundance and community composition and therefore need to be considered simultaneously with acidification.

Zooplankton are tiny drifting animals that play a critical role in aquatic food webs, linking phytoplankton to larger marine species.

Zooplankton

Baco, A. R., Morgan, N., Roark, E. B., Silva, M., Shamberger, K. E., &amp; Miller, K. (2017). Defying dissolution: discovery of deep-sea scleractinian coral reefs in the North Pacific. Scientific Reports, 7(1), 5436. <a href="https://doi.org/10.1038/s41598-017-05492-w">https://doi.org/10.1038/s41598-017-05492-w</a>

Cairns, S. D. (2007). Deep-water corals: an overview with special reference to diversity and distribution of deep-water scleractinian corals. Bulletin of Marine Science, 81(3), 311-322.

Fillinger, L., &amp; Richter, C. (2013). Vertical and horizontal distribution of Desmophyllum dianthus in Comau Fjord, Chile: a cold-water coral thriving at low pH. PeerJ, 1, e194. <a href="https://doi.org/10.7717/peerj.194">https://doi.org/10.7717/peerj.194</a>

Fisher, R., O’Leary, R. A., Low-Choy, S., Mengersen, K., Knowlton, N., Brainard, R. E., &amp; Caley, M. J. (2015). Species richness on coral reefs and the pursuit of convergent global estimates. Current Biology, 25(4), 500-505. <a href="https://doi.org/10.1016/j.cub.2014.12.022">https://doi.org/10.1016/j.cub.2014.12.022</a>

Guinotte JM, Orr J, Cairns S, Freiwald A, Morgan L, George R. 2006. Will human-induced changes in seawater chemistry alter the distribution of deep-sea scleractinian corals? Frontiers in Ecology and the Environment 4:141-146. <a href="https://doi.org/10.1890/1540-9295(2006)004[0141:WHCISC]2.0.CO;2">https://doi.org/10.1890/1540-9295(2006)004[0141:WHCISC]2.0.CO;2</a>

Hennige, S. J., Wicks, L. C., Kamenos, N. A., Perna, G., Findlay, H. S., &amp; Roberts, J. M. (2015). Hidden impacts of ocean acidification to live and dead coral framework. Proceedings of the Royal Society B: Biological Sciences, 282(1813), 20150990. <a href="https://doi.org/10.1098/rspb.2015.0990">https://doi.org/10.1098/rspb.2015.0990</a>

Kurman, M. D., Gomez, C. E., Georgian, S. E., Lunden, J. J., &amp; Cordes, E. E. (2017). Intra-specific variation reveals potential for adaptation to ocean acidification in a cold-water coral from the Gulf of Mexico. Frontiers in Marine Science, 4, 111. <a href="https://doi.org/10.3389/fmars.2017.00111">https://doi.org/10.3389/fmars.2017.00111</a>

Raybaud, V., Tambutté, S., Ferrier-Pagès, C., Reynaud, S., Venn, A. A., Tambutté, É., Nival, P, and Allemand, D. (2017). Computing the carbonate chemistry of the coral calcifying medium and its response to ocean acidification. Journal of Theoretical Biology, 424, 26-36. <a href="https://doi.org/10.1016/j.jtbi.2017.04.028">https://doi.org/10.1016/j.jtbi.2017.04.028</a>

Roberts, J. M., Wheeler, A. J., &amp; Freiwald, A. (2006). Reefs of the deep: the biology and geology of cold-water coral ecosystems. Science, 312(5773), 543-547. <a href="https://doi.org/10.1126/science.1119861">https://doi.org/10.1126/science.1119861</a>

Thresher, R., Tilbrook, B., Fallon, S., Wilson, N., &amp; Adkins, J. (2011). Effects of chronic low carbonate saturation levels on the distribution, growth and skeletal chemistry of deep-sea corals and other seamount megabenthos. Marine Ecology Progress Series, 442, 87–99. <a href="https://doi.org/10.3354/meps09400">https://doi.org/10.3354/meps09400</a>

While most people think of shallow water reefs when they think of corals, the deep-sea hosts an expansive habitat of corals far beneath the surface. These cold-water coral reefs can support a diversity of life and form important fishery habitat and nursery grounds.

Deep-sea surveys conducted by NOAA from 2012-2015 in the Mid-Atlantic, discovered an abundance of gorgonian sea fans and bamboo corals. In January of 2017, the new Frank R. Lautenberg Deep-Sea Coral Protection Area was created, safeguarding approximately 40,000 square miles of deep-sea coral habitat offshore from New York to Virginia. This area hosts a diversity of cold-water corals that are now protected from many types of commercial bottom fishing gear.

There have been few conclusive studies on the effects of acidification on deep-sea corals and effects often vary by species. While some research indicates that acidification may negatively impact cold-water stony corals, deep-sea explorations have observed resilience of scleractinian corals exposed to acidic conditions (aragonite saturation Ω &lt; 1) (Thresher et al., 2011). The mechanisms enabling them to thrive despite unfavorable calcification conditions remain mysterious. However, the capacity of deep-sea corals to alter their internal carbonate chemistry in favor of calcification has been proposed as a plausible explanation.
While there is contradictory evidence regarding the potential consequences of future ocean acidification levels on deep-sea corals, there is widespread agreement concerning its probable adverse effects. Acidification is expected to reduce the concentration of dissolved minerals needed for corals to make their skeletons, making it harder for corals to grow and repair themselves. Moreover, their slow growth and limited ability to recover make them particularly vulnerable to human activities such as bottom trawling, seabed mining, cable and pipe laying, and mineral, oil, and gas exploration.

Deep-sea corals are cold-water ecosystems that thrive without sunlight, providing vital habitats for diverse marine species.

Deep-sea Corals

Barton, A, Hales, B, Waldbusser, GG, Langdon, C, and Feely, RA. 2012. The Pacific oyster, Crassostrea gigas, shows negative correlation to naturally elevated carbon dioxide levels: Implications for near-term ocean acidification effects. Limnology and Oceanography 57(3): 698–710. <a href="https://doi.org/10.4319/lo.2012.57.3.0698">https://doi.org/10.4319/lo.2012.57.3.0698</a>

Clements, JC, Woodard, KD, and Hunt, HL. 2016. Porewater acidification alters the burrowing behavior and post-settlement dispersal of juvenile soft-shell clams (Mya arenaria). Journal of Experimental Marine Biology and Ecology, 477: 103-111. <a href="https://doi.org/10.1016/j.jembe.2016.01.013">https://doi.org/10.1016/j.jembe.2016.01.013</a>

Gazeau, F, Parker, LM, Comeau, S, Gattuso, JP, O’Connor, WA, Martin, S, Pörtner, HO, and Ross, PM. 2013. Impacts of ocean acidification on marine shelled molluscs. Marine Biology. 160: 2207-2245. <a href="https://doi.org/10.1007/s00227-013-2219-3">https://doi.org/10.1007/s00227-013-2219-3</a>

Gobler, CJ, et al. 2014. Hypoxia and Acidification Have Additive and Synergistic Negative Effects on the Growth, Survival, and Metamorphosis of Early Life Stage Bivalves. PLoS ONE. 9(1): e83648. <a href="https://doi.org/10.1371/journal.pone.0083648">https://doi.org/10.1371/journal.pone.0083648</a>

Green, MA, Waldbusser, GG, Hubazc, L, Cathcart, E, and Hall, J. 2013. Carbonate mineral saturation state as a recruitment cue for settling bivalves in marine muds. Estuaries and Coasts 36(1): 18-27. <a href="https://doi.org/10.1007/s12237-012-9549-0">https://doi.org/10.1007/s12237-012-9549-0</a>

Miller, AW, Reynolds, AC, Sobrino, C, and Riedel, GF. 2009. Shellfish face uncertain future in high CO2 world: influence of acidification on oyster larvae calcification and growth in estuaries. PLoS ONE, 4(5), e5661. <a href="https://doi.org/10.1371/journal.pone.0005661">https://doi.org/10.1371/journal.pone.0005661</a>

Ruesink, JL, van Raay, K, Witt, A, Herrold, S, Freshley, N, Sarich, A, and Trimble, AC. 2014. Spatio-Temporal Recruitment Variability of Naturalized Manila Clams (Ruditapes philippinarum) in Willapa Bay, Washington, USA. Fisheries Research 151: 199-204. <a href="http://dx.doi.org/10.1016/j.fishres.2013.11.011">http://dx.doi.org/10.1016/j.fishres.2013.11.011</a>

Talmage, SC and Gobler, CJ. 2010. Effects of past, present, and future ocean carbon dioxide concentrations on the growth and survival of larval shellfish. Proceedings of the National Academy of Sciences. 107: 17246–17251. <a href="https://doi.org/10.1073/pnas.0913804107">https://doi.org/10.1073/pnas.0913804107</a>

Waldbusser, GG, Bergschneider, H, and Green, MA. 2010. Size-dependent pH effect on calcification in post-larval hard clam Mercenaria spp. Marine Ecology Progress Series 417:171-182. <a href="https://doi.org/10.3354/meps08809">https://doi.org/10.3354/meps08809</a>

Waldbusser, GG, Voigt, EP, Bergschneider, H, Green, MA, and Newell, RI. 2011. Biocalcification in the eastern oyster (Crassostrea virginica) in relation to long-term trends in Chesapeake Bay pH. Estuaries and Coasts, 34(2): 221-231. <a href="https://doi.org/10.1007/s12237-010-9307-0">https://doi.org/10.1007/s12237-010-9307-0</a>

Waldbusser, GG, Hales, B, Langdon, CJ, Haley, BA, Schrader, P, Brunner, EL, Gray, M, Miller, C, and Gimenez, I. 2014. Saturation-state sensitivity of marine bivalve larvae to ocean acidification. Nature Climate Change, 5: 273–280. <a href="https://doi.org/10.1038/nclimate2479">https://doi.org/10.1038/nclimate2479</a>

Schwaner C, Barbosa M, Schwemmer TG, Pales Espinosa E, Allam B. Increased Food Resources Help Eastern Oyster Mitigate the Negative Impacts of Coastal Acidification. Animals. 2023 Mar 25;13(7):1161. <a href="https://doi.org/10.3390/ani13071161">https://doi.org/10.3390/ani13071161</a>

Mollusks are invertebrates, and their body forms vary widely from clams and scallops, to snails and slugs, to octopus and squid. Not only are mollusks a highly diverse group of animals, they are also the basis of a number of major world fisheries and a large component of global marine aquaculture.

In the Mid-Atlantic, bivalve and cephalopod mollusks – clams, oysters, scallops, and squid – are among the largest and most valuable commercial fisheries. Bivalve clams and oysters are also the foundation of the majority of marine aquaculture produced in the Mid-Atlantic region.
Many mollusks have shells made of calcium carbonate, a material that can be vulnerable to low pH or acidified conditions. In a recent review of species sensitivity to changing climate, the shellfisheries of the Mid-Atlantic were identified as being at particularly high risk of negative impacts due to both acidification and sea water temperature increases.

Kristen Jabanoski/Atlantic Sea Scallops

The larval stages of bivalves are especially sensitive to changes in pH and alkalinity, because their shells are thin, newly developing, and made of a highly soluble form of calcium carbonate called aragonite, which could dissolve easily at lower pH.
Low pH and undersaturation of calcium carbonate can easily dissolve thin aragonite shells and have been shown in laboratory experiments to lead to reduced survival and growth for bivalve larvae. In the Pacific and Northeast, calcium carbonate undersaturation has negatively impacted shellfish hatchery production, leading to regional and national economic impacts.

NOAA Fisheries/Eastern Oyster

Research suggests that later life stages of bivalves, like juvenile clams and oysters, may still be susceptible to OA. The sensitivity of bivalves to OA is highly variable among species and life stages. Further research is required to understand how OA interacts with impacts from other environmental conditions like increasing temperature and decreasing salinity, which are expected to occur due to climate change.
Nonetheless, the sensitivity of larval and young juvenile bivalves has important consequences in terms of population size and reproducibility of these economically and ecologically important species.

Mark Dixon NOAA Fisheries/Oysters

Bivalve shellfish are filter-feeders (remove particles and compounds from water) and important coastal ecosystem builders (create habitat for other species), and are often the focus of restoration and ecosystem resilience planning. To effectively implement coastal resilience or restoration priorities that include shellfish, it is imperative to better understand the ways that future acidified conditions will interact with these species throughout their life cycle.

Mark Dixon NOAA Fisheries/Surf Clam

Mollusks are a varied group of soft-bodied animals, many of which have hard shells. They are essential to both marine ecosystems and human economies.

Mollusks

Glandon, HL, Kilbourne, KH, Schijf, J, Miller, TJ. submitted. Counteractive effects of increased temperature and pCO2 on the carapace thickness and chemistry of juvenile blue crab, Callinectes sapidus, from the Patuxent River, Chesapeake Bay. Journal of Experimental Marine Biology and Ecology, 498, 39–45. <a href="https://doi.org/10.1016/j.jembe.2017.11.005">https://doi.org/10.1016/j.jembe.2017.11.005</a>

Glandon, HL, Miller, TJ. 2017. No effect of high pCO2 on juvenile blue crab, Callinectes sapidus, growth and consumption despite positive responses to concurrent warming. ICES Journal of Marine Science: Journal du Conseil 74, 1201-1209. <a href="https://doi.org/10.1093/icesjms/fsw171">https://doi.org/10.1093/icesjms/fsw171</a>

Glitz, SM, Taylor, CM. 2017. Reduced growth and survival in the larval blue crab Callinectes sapidus under predicted ocean acidification. Journal of Shellfish Research 36, 481-485. <a href="https://doi.org/10.2983/035.036.0219">https://doi.org/10.2983/035.036.0219</a>

Kroeker, KJ, Kordas, RL, Crim, R, Hendriks, IE, Ramajo, L, Singh, GS, Duarte, CM, Gattuso, JP. 2013. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology 19, 1884-1896. <a href="https://doi.org/10.1111/gcb.12179">https://doi.org/10.1111/gcb.12179</a>

Ries, JB, Cohen, AL, McCorkle, DC. 2009. Marine calcifiers exhibit mixed responses to CO2-induced ocean acidification. Geology 37, 1131-1134. <a href="https://doi.org/10.1130/G30210A.1">https://doi.org/10.1130/G30210A.1</a>

Coffey, W. D., Nardone, J. A., Yarram, A., Long, W. C., Swiney, K. M., Foy, R. J., &amp; Dickinson, G. H. (2017). Ocean acidification leads to altered micromechanical properties of the mineralized cuticle in juvenile red and blue king crabs. Journal of Experimental Marine Biology and Ecology, 495, 1–12. <a href="https://doi.org/10.1016/j.jembe.2017.05.011">https://doi.org/10.1016/j.jembe.2017.05.011</a>

Crustacean species support productive fisheries in the Mid-Atlantic region, making them not only ecologically important, but critical to the region&#8217;s economy. Certain crustacean species, such as the blue crab, are essential (keystone) species which also serve as a link between the ocean floor (benthic) and the open ocean (pelagic) environment.
Decapods are an order of crustacean, which include the following:
<ul>
<li>Crabs</li>
<li>Lobsters</li>
<li>Shrimp</li>
</ul>

There have been limited studies on crustacean responses to acidification, and those studies have demonstrated variable responses in growth and survival under acidified conditions.
Studies have found that:
<ul>
<li>Decapods are less sensitive to acidification than other calcifiers due to their efficient shell-building processes</li>
<li>Decapod responses to acidification depend on length of exposure to a pH range of 7.40 to 7.80</li>
<li>Younger life stages of crustaceans are more sensitive to acidification than juveniles and adults</li>
</ul>

Early life stages of crustaceans are more sensitive to ocean acidification than juveniles and adults because of higher metabolism, growth and shell forming rates, stronger stress responses to low oxygen, and higher mortality.
Studies have found that:
<ul>
<li>Larval blue crabs have lower survival and smaller size at a reduced pH</li>
<li>In a laboratory setting, adult blue crabs calcify more quickly when exposed to high acidity</li>
<li>In juvenile blue crab studies, acidic conditions:
<ul>
<li>increased calcium carbonate; and</li>
<li>did not impact growth rate or food consumption.</li>
</ul>
</li>
</ul>

Board Members

Despite the fact that older crustaceans may be less vulnerable to ocean acidification, it is important to take into account the higher vulnerability of younger crustaceans to understand how populations of crustacean species will be affected in the future.
In order to fully understand crustaceans&#8217; responses to future climate stressors, more studies must be conducted on additional species at different life stages.

Our crustacean species are ecologically important, and critical to the economy of the Mid-Atlantic.

Crustaceans

Bach, L. T., Riebesell, U., &amp; Schulz, K. G. (2011). Distinguishing between the effects of ocean acidification and ocean carbonation in the coccolithophore Emiliania huxleyi. Limnology and Oceanography, 56(6), 2040–2050. <a href="https://doi.org/10.4319/lo.2011.56.6.2040">https://doi.org/10.4319/lo.2011.56.6.2040</a>

Eggers, S. L., Lewandowska, A. M., Barcelos E Ramos, J., Blanco‐Ameijeiras, S., Gallo, F., &amp; Matthiessen, B. (2014). Community composition has greater impact on the functioning of marine phytoplankton communities than ocean acidification. Global Change Biology, 20(3), 713–723. <a href="https://doi.org/10.1111/gcb.12421">https://doi.org/10.1111/gcb.12421</a>

Fu, F., Place, A., Garcia, N., &amp; Hutchins, D. (2010). CO2 and phosphate availability control the toxicity of the harmful bloom dinoflagellate Karlodinium veneficum. Aquatic Microbial Ecology, 59, 55–65. <a href="https://doi.org/10.3354/ame01396">https://doi.org/10.3354/ame01396</a>

Fu, F., Warner, M. E., Zhang, Y., Feng, Y., &amp; Hutchins, D. A. (2007). Effects of increased temperature and CO2 on photosynthesis, growth, and elemental ratios in marine Synechococcus and Prochlorococcus (Cyanobacteria). Journal of Phycology, 43(3), 485–496. <a href="https://doi.org/10.1111/j.1529-8817.2007.00355.x">https://doi.org/10.1111/j.1529-8817.2007.00355.x</a>

Goldman, J. A. L., Bender, M. L., &amp; Morel, F. M. M. (2017). The effects of pH and pCO2 on photosynthesis and respiration in the diatom Thalassiosira weissflogii. Photosynthesis Research, 132(1), 83–93. <a href="https://doi.org/10.1007/s11120-016-0330-2">https://doi.org/10.1007/s11120-016-0330-2</a>

Hong, H., Shen, R., Zhang, F., Wen, Z., Chang, S., Lin, W., Kranz, S. A., Luo, Y.-W., Kao, S.-J., Morel, F. M. M., &amp; Shi, D. (2017). The complex effects of ocean acidification on the prominent N2 -fixing cyanobacterium Trichodesmium. Science, 356(6337), 527–531. <a href="https://doi.org/10.1126/science.aal2981">https://doi.org/10.1126/science.aal2981</a>

Hoppe, C. J. M., Hassler, C. S., Payne, C. D., Tortell, P. D., Rost, B., &amp; Trimborn, S. (2013). Iron Limitation Modulates Ocean Acidification Effects on Southern Ocean Phytoplankton Communities. PLoS ONE, 8(11), e79890. <a href="https://doi.org/10.1371/journal.pone.0079890">https://doi.org/10.1371/journal.pone.0079890</a>

Kim, J.-M., Lee, K., Shin, K., Kang, J.-H., Lee, H.-W., Kim, M., Jang, P.-G., &amp; Jang, M.-C. (2006). The effect of seawater CO2 concentration on growth of a natural phytoplankton assemblage in a controlled mesocosm experiment. Limnology and Oceanography, 51(4), 1629–1636. <a href="https://doi.org/10.4319/lo.2006.51.4.1629">https://doi.org/10.4319/lo.2006.51.4.1629</a>

King, A., Jenkins, B., Wallace, J., Liu, Y., Wikfors, G., Milke, L., &amp; Meseck, S. (2015). Effects of CO2 on growth rate, C:N:P, and fatty acid composition of seven marine phytoplankton species. Marine Ecology Progress Series, 537, 59–69. <a href="https://doi.org/10.3354/meps11458">https://doi.org/10.3354/meps11458</a>

Passow, U., &amp; Laws, E. A. (2015). Ocean acidification as one of multiple stressors: Growth response of Thalassiosira weissflogii (diatom) under temperature and light stress. Marine Ecology Progress Series, 541, 75–90. <a href="https://doi.org/10.3354/meps11541">https://doi.org/10.3354/meps11541</a>

Shi, D., Xu, Y., Hopkinson, B. M., &amp; Morel, F. M. M. (2010). Effect of Ocean Acidification on Iron Availability to Marine Phytoplankton. Science, 327(5966), 676–679. <a href="https://doi.org/10.1126/science.1183517">https://doi.org/10.1126/science.1183517</a>

Tatters, A. O., Roleda, M. Y., Schnetzer, A., Fu, F., Hurd, C. L., Boyd, P. W., Caron, D. A., Lie, A. A. Y., Hoffmann, L. J., &amp; Hutchins, D. A. (2013). Short- and long-term conditioning of a temperate marine diatom community to acidification and warming. Philosophical Transactions of the Royal Society B: Biological Sciences, 368(1627), 20120437. <a href="https://doi.org/10.1098/rstb.2012.0437">https://doi.org/10.1098/rstb.2012.0437</a>

Wu, Y., Campbell, D. A., Irwin, A. J., Suggett, D. J., &amp; Finkel, Z. V. (2014). Ocean acidification enhances the growth rate of larger diatoms. Limnology and Oceanography, 59(3), 1027–1034. <a href="https://doi.org/10.4319/lo.2014.59.3.1027">https://doi.org/10.4319/lo.2014.59.3.1027</a>

Xu, Y., Shi, D., Aristilde, L., &amp; Morel, F. M. M. (2012). The effect of pH on the uptake of zinc and cadmium in marine phytoplankton: Possible role of weak complexes. Limnology and Oceanography, 57(1), 293–304. <a href="https://doi.org/10.4319/lo.2012.57.1.0293">https://doi.org/10.4319/lo.2012.57.1.0293</a>

Like land plants, phytoplankton use sunlight to convert carbon dioxide (CO2) and water into organic carbon for their body parts and release oxygen as a byproduct of photosynthesis. CO2 is therefore an essential nutrient for phytoplankton and higher concentrations of CO2 in the surface ocean have the potential to support higher rates of phytoplankton photosynthesis and growth.
Phytoplankton are essential for removing CO2 from the water and supplying O2, however, this balance can be disturbed when there is excess CO2 in the water.

The impacts of acidification to phytoplankton are highly complex and not well understood. With over 100,000 different species of phytoplankton, the responses of each individual species to acidification are highly varied and challenging to pinpoint. In laboratory experiments with pure cultures of individual species of phytoplankton, little or no change in growth is typically observed in cultures grown with CO2 levels expected in the year 2100.
However, other more subtle effects have been noted including interactions of elevated CO2 with demand for other nutrients such as nitrogen, phosphorus, and iron, which suggest that higher CO2 may be most beneficial to phytoplankton under nutrient rich conditions. Conversely, elevated CO2 can lead to reduced phytoplankton growth when occurring in combination with light or temperature stress.

Elizabeth Cosper/Brown Tide Aerial

While the effects of acidification on many phytoplankton species remain unclear, some information has been discovered about several key species important in coastal waters and central ocean basins.
Coccolithophores: In coccolithophores, a species of phytoplankton that produce calcium carbonate plates on their cell surface, decreases in pH can alter growth, calcification, and organic carbon production.
Trichodesmium: Lower pH may negatively affect the ability of Trichodesmium, an important species of photosynthetic cyanobacteria, to provide inorganic nitrogen to the ocean through nitrogen fixation, particularly in the vast areas of the ocean that are generally limited by nitrogen.

Harmful algal blooms (HABs) occur when there is rapid growth of certain species of phytoplankton, including Karenia brevis (red tide) and Aureococcus anophagefferens (brown tide), resulting in toxic conditions for both marine species and humans. Phytoplankton, such as Karenia brevis (red tide), tend to thrive in high CO2 conditions. Aureococcus anophagefferens is another HAB species that thrives under high nitrogen and phosphorus conditions, which often accompany high CO2 conditions. HABs are considered co-stressors to acidic conditions and can have compounding negative impacts on coastal habitat and animals. Some species of Karenia have been found as far north as New Jersey but are more common in southeastern US waters. As ocean water temperatures increase, it is expected that more of these species will be found farther north.

As multiple factors influence photosynthesis and growth of phytoplankton in the ocean, it is difficult to predict the effects of higher CO2 on the productivity of natural phytoplankton communities. For example, concurrent increases in both CO2 and temperature could enhance phytoplankton or macroalgae growth, however, as in the case of HABs, this increase in growth is not always good for the environment or animals. Similarly, increases in CO2 expected over the next 100 years may favor the growth of larger diatom species whose growth can be limited by lower CO2 and nutrient levels. Diatoms are known to require more nutrients and CO2 than other species. Increases in CO2 levels in the open ocean and coastal waters could lead to changes in phytoplankton community composition with potential secondary effects on biogeochemical cycles and food webs.

Marine phytoplankton are microscopic, photosynthetic organisms that form the foundation of the ocean&#8217;s food web and produce over half of Earth&#8217;s oxygen.

Marine Phytoplankton

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Special Announcement

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Events

Stay informed on the latest research, partnerships, and regional efforts to address ocean and coastal acidification.

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Browse Webinars

Don't miss out, Explore our on-demand webinars.

The  Mid-Atlantic Coastal Acidification Network&#8217;s (MACAN) annual webinar series launches January 26! Join us to learn about the latest research on flounder, forage fish, and acidification in coastal waters from Chris Chambers, a research fishery biologist at NOAA.
In February, we&#8217;ll explore the impacts of ocean acidification and other climate change impacts on shipwrecks, shell middens, and cultural resources with Susan Langley, Maryland&#8217;s State Underwater Archaeologist. March and April webinar topics will be available soon. 
<figure id="attachment_5703" aria-describedby="caption-attachment-5703" style="width: 603px" class="wp-caption aligncenter"><img loading="lazy" decoding="async" class="wp-image-5703 size-full" src="https://macancms.3lanemarketing.com/wp-content/uploads/2025/07/rsw_1280-6.webp" alt="" width="603" height="452" srcset="https://macancms.3lanemarketing.com/wp-content/uploads/2025/07/rsw_1280-6.webp 603w, https://macancms.3lanemarketing.com/wp-content/uploads/2025/07/rsw_1280-6-300x225.webp 300w" sizes="auto, (max-width: 603px) 100vw, 603px" /><figcaption id="caption-attachment-5703" class="wp-caption-text">A 150-year-old locomotive wreck off the New Jersey coast (photo by Monmouth University)</figcaption></figure>

Webinars to Explore Acidification Impacts on Fish, Shipwrecks

Join us on April 12 at 1 p.m. for &#8216;U.S. State-Led OA Action Planning in the Mid-Atlantic.&#8217; 
<a class="x-el x-el-a c2-9 c2-a c2-53 c2-c c2-d c2-54 c2-f c2-55 c2-3 c2-3j c2-n c2-10 c2-p" href="https://register.gotowebinar.com/register/5804464133441407245" target="_blank" rel="noopener noreferrer">Click here</a> to register for this free discussion.   
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U.S. State-Led OA Action Planning in the Mid-Atlantic

Monday, September 11, 1:00-5:00 PM
Session 1: Assessing Vulnerability in Mid-Atlantic Species, Ecosystems, and Industries
This session will focus on the biological impacts and socioeconomic vulnerability of species, habitats, and the shellfish industry in the Mid-Atlantic. Lessons learned from interviews with growers and fishermen about their adaptation capacity will also be highlighted.
Session 2: New Initiatives in Outreach and Community Engagement
This session will focus on the latest outreach initiatives and available resources from the East Coast CAN’s (coastal acidification networks) and their partners (OAP, The OA Alliance, and the Aquarium Conservation Partnership).
Session 3: Updates on Federal and State OA Initiatives and DEIJA Considerations
This session will provide an overview of national, federal, and state initiatives in monitoring and mitigating COA. There will be an extended time for discussion at the end of this session.
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Tuesday, September 12 9:00-2:30 PM
Session 1: Monitoring, Technology, and Data to Inform Management Decisions
This session will highlight some of the latest research, monitoring, and data tools being developed for community scientists, resource managers, and the aquaculture industry.
Session 2: mCDR and Panel Discussion
mCDR is a key component of the national Ocean Climate Action Plan (OCAP). This session will focus on newly funded NOAA projects, governance considerations, and how industry is advancing mCDR monitoring, reporting, and verification methods.
Session 3: Nature-Based Solutions for healthy ecosystems and mCDR:
This session will discuss approaches to mCDR and maintaining healthy ecosystems through restoration or enhancement of shellfish, SAV, and ecologically important habitats.

MACAN Coastal & Ocean Acidification Workshop

MACAN’s biennial state-of-the-science meeting and technical assistance workshop will be hosted in partnership with the NOAA Ocean Acidification Program (OAP) from July 15-17 at the Smithsonian Environmental Research Center, in Edgewater, Maryland.
<a href="https://macancms.3lanemarketing.com/wp-content/uploads/2025/07/MACAN_Workshop_5-28-25.pdf" target="_blank" rel="noopener">A draft agenda can be viewed here.</a>
<img loading="lazy" decoding="async" class="size-medium wp-image-5268 alignright" src="https://macancms.3lanemarketing.com/wp-content/uploads/2025/04/1752850971770-300x200.png" alt="" width="300" height="200" srcset="https://macancms.3lanemarketing.com/wp-content/uploads/2025/04/1752850971770-300x200.png 300w, https://macancms.3lanemarketing.com/wp-content/uploads/2025/04/1752850971770-1024x682.png 1024w, https://macancms.3lanemarketing.com/wp-content/uploads/2025/04/1752850971770-768x512.png 768w, https://macancms.3lanemarketing.com/wp-content/uploads/2025/04/1752850971770.png 1310w" sizes="auto, (max-width: 300px) 100vw, 300px" />
Workshop goals include:
<ul class="wp-block-list">
<li>Improve/support regional collaboration on standards of practice/validation methods for various types of instruments and coastal and estuarine waters</li>
<li>Build capacity to fill spatio-temporal gaps in coastal acidification monitoring, by connecting people and resources to set up effective monitoring, while leveraging existing programs/sensors</li>
<li>Build capacity for mCDR readiness (monitoring, research, and validation)</li>
<li>Strengthen connections and collaborations across regional CANs</li>
</ul>
The event is free to attend. <a href="https://docs.google.com/forms/d/e/1FAIpQLSeOhkkwkc_8nESz_36Y9TdFZQz4PPQgIoNluJAak-SfgKPjTg/closedform" target="_blank" rel="noopener">Registration</a> is required. Questions can be directed to Kirstin Wakefield at <a href="mailto:kirstin@maracoos.org">kirstin@maracoos.org</a>.
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Who should attend?
State, Federal, and Tribal agencies and resource managers, water quality analysts, acidification researchers and modelers, mCDR industry members, blue carbon practitioners, aquaculture and fishery industry members.
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Hotel Room Blocks
The following hotel options are available at a discounted conference rate.
Hilton Garden Inn Annapolis
Cost: $109 per night
Last Day to Book: Saturday, June 14, 2025
<a href="https://www.hilton.com/en/book/reservation/rooms/?ctyhocn=BWIANGI&amp;arrivalDate=2025-07-18&amp;departureDate=2025-07-20&amp;groupCode=MARC&amp;room1NumAdults=1&amp;cid=OM%2CWW%2CHILTONLINK%2CEN%2CDirectLink" target="_blank" rel="noopener">CLICK HERE</a> for reservations and more information.
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SpringHill Suites Annapolis
Cost: $161 per night
Last Day to Book: Saturday, June 14, 2025
<a href="https://www.marriott.com/event-reservations/reservation-link.mi?id=1741119693367&amp;key=GRP&amp;guestreslink2=true&amp;app=resvlink" target="_blank" rel="noopener">CLICK HERE</a> for reservations and more information

MACAN State of the Science and Technical Training Workshop

State of Coastal and Ocean Acidification in the U.S. Mid-Atlantic
<img loading="lazy" decoding="async" class="size-medium wp-image-5777 alignleft" src="https://macancms.3lanemarketing.com/wp-content/uploads/2025/08/Grace-Saba1-300x300.webp" alt="" width="300" height="300" srcset="https://macancms.3lanemarketing.com/wp-content/uploads/2025/08/Grace-Saba1-300x300.webp 300w, https://macancms.3lanemarketing.com/wp-content/uploads/2025/08/Grace-Saba1-1024x1024.webp 1024w, https://macancms.3lanemarketing.com/wp-content/uploads/2025/08/Grace-Saba1-150x150.webp 150w, https://macancms.3lanemarketing.com/wp-content/uploads/2025/08/Grace-Saba1-768x768.webp 768w, https://macancms.3lanemarketing.com/wp-content/uploads/2025/08/Grace-Saba1.webp 1120w" sizes="auto, (max-width: 300px) 100vw, 300px" />
Coastal and ocean acidification have significant scientific and societal ramifications including the alteration of ocean biogeochemistry, ecological consequences associated with altered ecosystems, and economic losses due to the decreased survival of commercially important organisms. Guest speaker Dr. Grace Saba, Assistant Professor in the Department of Marine and Coastal Sciences, Center for Ocean Observing Leadership at Rutgers University will cover what we know and do not yet know about acidification in the Mid-Atlantic. We will examine recommendations from the Mid-Atlantic Coastal Acidification Network (MACAN) to enhance regional acidification monitoring and improve understanding of potential ecological impacts.
Free and open to the public

UCI Marine and Environmental Luncheon Speaker Series

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If you are interested in learning more about MACAN and the work we do, please sign up for our <a href="https://macan.vercel.app/subscribe/">monthly newsletter</a>. You can also read our <a href="https://macancms.3lanemarketing.com/wp-content/uploads/2025/09/MACAN-5-Year-Workplan-2024-2028.pdf" target="_blank" rel="noopener">2024 to 2028 Work Plan</a>.

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About Us

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MACAN’s committed to understanding, predicting, and mitigating the impact of acidification on our oceans and coastal ecosystems.

A collaborative team committed to addressing the pressing environmental issue of coastal acidification in our region.

What is Acidification

Increased atmospheric carbon dioxide drives ocean acidification, lowering pH.

Diverse monitoring addresses complex coastal and estuarine acidification drivers.

Factors such as geography, climate, and human activities vary across different regions, impacting the extent and rate of ocean acidification.

Ocean acidification is driven by excess global carbon dioxide and water pollution from land runoff, and there are ways communities can help.

Species Impact

Converting ocean acidification data into insights about the species living in our water.

Microscopic marine plants that form the base of ocean food webs.

Blue crabs are crucial to Mid-Atlantic ecology and economy.

Gorgonian sea fans and bamboo corals create vital deep-sea habitats.

A diverse group of animals vital to fisheries.

Mid-Atlantic finfish are essential to marine ecosystems and economies alike.

Vital food web organisms with varying responses.

SAV, including eelgrass, provide vital coastal habitat.

Highly complex webs of species that mix in space and time.

Webinars

OA Policy and mCDR

Ocean acidification action planning is states coordinating efforts to monitor, mitigate, and build resilience against acidification threats.

Marine carbon dioxide removal (mCDR) is a technique being investigated to mitigate climate change.

News & Events

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