Biology Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/2749

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    Influence of prey density and dietary supplementation on the growth and development of the blue crab, Callinectes sapidus
    (2017) Maurer, Leah Marie; Chung, Sook; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The early developmental stages of arthropods often vary and appear to be influenced by dietary conditions. It is hypothesized that food availability and dietary components may affect the number and length of developmental stages of the blue crab, Callinectes sapidus, specifically those that are reared in aquaculture settings. This hypothesis was examined with C. sapidus 1) larvae and 2) juveniles. 1) During the zoeal period, development from stage 1 to megalopae was monitored under a full factorial experiment with treatments: high and low prey density coupled with and without poly-β-hydroxybutyrate (PHB) supplementations. Our data showed that prey density influences variation in the zoeal development of C. sapidus by increasing stage skipping, reducing the number of the stages from 7-8 to 5-8. Additionally, a high prey density coupled with PHB supplementation caused increasing instances of stage skipping. 2) During the juvenile period, the growth was monitored for three molting events (57-165 days) under the following treatments: 0, 5, 10, and 20% chitin supplemented diets and squid control. Our data showed that chitin supplementation did not affect the growth of the juvenile C. sapidus (molt increment or interval).
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    Influence of environmental conditions on the age, hatch dates, and growth of juvenile Atlantic menhaden in the Choptank River, MD
    (2016) Atkinson, Alexandra Nicole; Secor, David H; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Since 1993 Atlantic menhaden has experienced sustained low juvenile production (recruitment) in the Chesapeake Bay. Factors controlling growth, abundance, and mortality of larval and juvenile menhaden change throughout ontogeny such that larval growth rates could carry over to juvenile growth and survival. The effects of winter thermal conditions on the hatch dates and growth of larval and juvenile Atlantic menhaden in Atlantic shelf and Chesapeake Bay habitats were examined using otolith (ear-stone) increment analyses and growth models. For 2010-2013, truncated hatch-date distributions provided evidence for a winter recruitment bottleneck in Atlantic menhaden caused by cold temperatures. Hatch-dates of surviving juveniles were skewed towards warmer months for years characterized by colder temperatures. Reduced larval growth rates, influenced by reduced temperature and food availability, carried over to juvenile growth rates. A growing degree-day model performed well in simulating observed juvenile growth rates in the Choptank River tributary of Chesapeake Bay.