Sponsor
Portland State University. Department of Environmental Science and Management
First Advisor
Paola López-Duarte
Term of Graduation
Summer 2026
Date of Publication
7-28-2026
Document Type
Thesis
Degree Name
Master of Science (M.S.) in Environmental Science and Management
Department
Environmental Science and Management
Language
English
Subjects
Climate warming, Embryonic development, Estuarine crabs, Estuarine crabs, Larval survival, Thermal sensitivity
Physical Description
1 online resource (ix, 101 pages)
Abstract
Temperature is a major driver of physiological and developmental processes in marine organisms, and continued climate warming is expected to affect reproduction and recruitment in estuarine species. Early life stages are often particularly sensitive to environmental stress, yet relatively little is known about how warming influences embryonic development, hatching success, and larval survival across co-occurring native and introduced crab species.
This study examined the effects of temperature on embryonic development, hatching success, and early larval survival in four estuarine crab species from the Pacific Northwest: the introduced European green crab, Carcinus maenas, and the native shore crabs Hemigrapsus nudus, Hemigrapsus oregonensis, and Pachygrapsus crassipes. Gravid females were maintained under controlled laboratory conditions across environmentally relevant temperature treatments, and embryos were monitored throughout development. Larval survival was assessed during the first four days following hatching. Comparisons between attached and detached embryos in C. maenas were conducted to evaluate the potential role of maternal care during embryonic development.
Warmer temperatures accelerated embryonic development across all study species, supporting predictions that rising temperatures increase developmental rates in marine ectotherms. In C. maenas, developmental rates more than doubled between 12°C and 20°C, and similar warming-associated increases in developmental progression were observed in H. nudus, H. oregonensis, and P. crassipes. Cross-species analyses further indicated that the magnitude of developmental acceleration differed among species. However, faster development did not consistently result in greater reproductive success. Detached C. maenas embryos exhibited significantly lower hatching success at 20°C than at 12°C or 16°C, and H. nudus showed evidence of thermal stress through embryo consumption and reduced larval performance at elevated temperatures. In contrast, P. crassipes maintained relatively strong developmental and larval performance under warmer conditions. Across treatments, attached embryos generally performed better than detached embryos, suggesting that maternal care may help buffer embryos from environmental stress.
These findings indicate that in addition to accelerating embryonic development, warming also produces species-specific impacts on hatching success and larval survival. Differences in thermal sensitivity among species may be associated with reproductive seasonality, habitat-associated thermal exposure, and life-history characteristics. As ocean temperatures continue to rise, variation in early-life-stage responses to warming may influence recruitment dynamics, species interactions, and community structure within Pacific Northwest estuarine ecosystems.
Rights
© 2026 Keria Moritsugu-Vandehey
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
Persistent Identifier
https://archives.pdx.edu/ds/psu/45138
Recommended Citation
Moritsugu-Vandehey, Keria, "Thermal Sensitivity of Native and Introduced Crabs: Implications for Reproductive Success" (2026). Dissertations and Theses. Paper 7204.