Date

2002

Document Type

Capstone Project

Degree Name

Bachelor of Science (B.S.)

Department

Science & Environmental Policy

Abstract

Crabs play an important role in Elkhorn Slough. The three main species found in the slough, that are native to it, and that I will be looking at are Pachygrapsus crassipes, the striped shore crab, Hemigrapsus oregonensis, the yellow shore crab, and Cancer antennarius, the Pacific Rock Crab. There is one non native species of crab that is found in the slough, the European green crab, Carcinus maenas. Not much is known about the population sizes of any of these four crab species. The goal of my project was to create and implement a long term monitoring program that could be carried out by interns and or volunteers and school groups. The research question I wanted to answer was whether or not the crab populations change over time and if they do why. In order to monitor the populations of crabs in the slough I chose four trapping sites in the upper part of the slough that had easy accessibility and not too much disturbance from the tides and people. At each of these sites, the size, sex, and species of each crab that was caught was recorded. After eleven months of collecting data I found that Hemigrapsus oregonensis was the most abundant crab in the slough and that Kirby Park had the largest population of crabs. The populations of all the four crab species changed with time and that there were more male crabs caught than females. I don't know why this is and I think in order to come to a more precise conclusion more research needs to be done for a longer period of time to see if the fluctuations in populations are seasonal, due to rain, or some other unknown source.

Comments

Capstone Project (B.S.) Earth Systems Science & Policy Institute

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