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Many marine species have been shown to be threatened by both ocean acidification and ocean warming which are reducing survival, altering behavior, and posing limits on physiology, especially during earlier life stages. The commercially important Florida stone crab, Menippe mercenaria , is one species that is affected by reduced seawater pH and elevated seawater temperatures. In this study, we determined the impacts of reduced pH and elevated temperature on the distribution of the stone crab larvae along the West Florida Shelf. To understand the dispersion of the larvae, we coupled the multi-scale ocean model SLIM with a larval dispersal model. We then conducted a connectivity study and evaluated the impacts of climate stressors by looking at four different scenarios which included models that represented the dispersion of stone crab larvae under: 1) present day conditions as modelled by SLIM for the temperature and NEMO-PISCES for the pH, 2) SSP1-2.6 scenario (-0.037 reduction in pH and +0.5°C compared to present-day conditions), 3) SSP2-4.5 scenario(-0.15 reduction in pH and +1.5°C) and 4) SSP5-8.5 scenario (-0.375 reduction in pH and +3.5°C). Our results show a clear impact of these climate change stressors on larval dispersal and on the subsequent stone crab distribution. Our results indicate that future climate change could result in stone crabs moving north or into deeper waters. We also observed an increase in the number of larvae settling in deeper waters (defined as the non-fishing zone in this study with depths exceeding 30 m) that are not typically part of the commercial fishing zone. The distance travelled by larvae, however, is likely to decrease, resulting in an increase of self-recruitment and decrease of the size of the sub-populations. A shift of the spawning period, to earlier in the spring, is also likely to occur. Our results suggest that habitats in the non-fishing zone cannot serve as a significant source of larvae for the habitats in the fishing zone (defined as water depth< 30 m) since there is very little exchange (< 5% of all exchanges) between the two zones. These results indicate that the stone crab populations in Florida may be susceptible to community fragmentation and that the management of the fishery should consider the potential impacts of future climate change scenarios.
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Will Climate Change Alter the Swimming Behavior of Larval Stone Crabs?: A Guided-Inquiry Lesson
The ocean has absorbed ~one third of the excess atmospheric carbon dioxide (CO2) released since the Industrial Revolution. When the ocean absorbs excess CO2, a series of chemical reactions occur that result in a reduction in seawater pH, a process called ocean acidification. The excess atmospheric CO2 is also resulting in warmer seawater temperatures. These stressors pose a threat to marine organisms, especially during earlier life stages (i.e., larvae). The larvae of species like the Florida stone crab (Menippe mercenaria) are free swimming, allowing a population to disperse and recruit into new habitats. After release, stone crab larvae undergo vertical swimming excursions in response to abiotic stimuli (gravity, light, pressure) allowing them to control their depth. Typically, newly hatched larvae respond to abiotic cues that would promote a shallower depth distribution, where surface currents can transport them offshore to complete development. As larvae develop offshore, they become less sensitive to certain abiotic stimuli, which promotes a deeper depth distribution that may expose them to variable current speeds, thus influencing the direction of advection (horizontal movement). Environmental stressors like ocean acidification and elevated seawater temperatures may also impact the larvae’s natural response to these abiotic stimuli throughout ontogeny (development). Changes in their natural swimming behavior due to climate stressors could, therefore, influence the transport and dispersal of the species. This guided-inquiry lesson challenges introductory marine biology and oceanography students to determine how future ocean pH and temperature projections could impact the swimming behavior of Florida stone crab larvae.
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- Award ID(s):
- 2049047
- PAR ID:
- 10593377
- Publisher / Repository:
- Ubiquity Press
- Date Published:
- Journal Name:
- Current: The Journal of Marine Education
- Volume:
- 39
- Issue:
- 2
- ISSN:
- 0889-5546
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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This guided, inquiry-based, hands-on lesson uses data from a local monitoring station in Tampa Bay, Florida, to guide students toward understanding how coastal acidification may impact the reproductive success of the Florida stone crab, an important regional fishery. The objectives of the lesson are for students to: (1) determine how pH varies between different habitats, (2) determine how pH can affect the reproductive success of an important commercial fishery, the Florida stone crab, and (3) evaluate whether exposure to variable seawater pH results in greater reproductive success in stone crabs relative to individuals that are not exposed to pH variability.more » « less
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Abstract Anthropogenic activities like habitat degradation, excess nutrient runoff, and sewage outfalls can decrease seawater pH in coastal environments. Coastal waters can also experience frequent fluctuations in seawater pH due to biological activity (i.e., photosynthesis and respiration). Commercially important species like the Florida stone crab, Menippe mercenaria (Say, 1818), inhabit coastal waters and experience fluctuations in seawater pH on both diurnal and seasonal scales. Organisms exposed to reductions in seawater pH may have difficulty sensing chemical cues due to physiological changes and the associated metabolic stress of compensating for a more acidic environment. Here we determined the foraging activity of the Florida stone crab when exposed to reduced pH conditions (control pH 7.8, reduced pH 7.6). The impacts of reduced pH on foraging activity were determined by monitoring activity time, stress, predation attempts, and handling time when crabs were exposed to lower seawater pH for 12 hrs. Crabs exposed to reduced pH conditions experienced elevated stress levels and reduced activity than crabs in the control pH treatment. These results suggest that exposure to more extreme pH conditions may limit the foraging activity of stone crabs.more » « less
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Rising atmospheric CO 2 reduces seawater pH causing ocean acidification (OA). Understanding how resilient marine organisms respond to OA may help predict how community dynamics will shift as CO 2 continues rising. The common slipper shell snail Crepidula fornicata is a marine gastropod native to eastern North America that has been a successful invader along the western European coastline and elsewhere. It has also been previously shown to be resilient to global change stressors. To examine the mechanisms underlying C. fornicata’s resilience to OA, we conducted two controlled laboratory experiments. First, we examined several phenotypes and genome-wide gene expression of C. fornicata in response to pH treatments (7.5, 7.6, and 8.0) throughout the larval stage and then tested how conditions experienced as larvae influenced juvenile stages (i.e., carry-over effects). Second, we examined genome-wide gene expression patterns of C. fornicata larvae in response to acute (4, 10, 24, and 48 h) pH treatment (7.5 and 8.0). Both C. fornicata larvae and juveniles exhibited resilience to OA and their gene expression responses highlight the role of transcriptome plasticity in this resilience. Larvae did not exhibit reduced growth under OA until they were at least 8 days old. These phenotypic effects were preceded by broad transcriptomic changes, which likely served as an acclimation mechanism for combating reduced pH conditions frequently experienced in littoral zones. Larvae reared in reduced pH conditions also took longer to become competent to metamorphose. In addition, while juvenile sizes at metamorphosis reflected larval rearing pH conditions, no carry-over effects on juvenile growth rates were observed. Transcriptomic analyses suggest increased metabolism under OA, which may indicate compensation in reduced pH environments. Transcriptomic analyses through time suggest that these energetic burdens experienced under OA eventually dissipate, allowing C. fornicata to reduce metabolic demands and acclimate to reduced pH. Carry-over effects from larval OA conditions were observed in juveniles; however, these effects were larger for more severe OA conditions and larvae reared in those conditions also demonstrated less transcriptome elasticity. This study highlights the importance of assessing the effects of OA across life history stages and demonstrates how transcriptomic plasticity may allow highly resilient organisms, like C. fornicata , to acclimate to reduced pH environments.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5334/cjme.117
