Distribution, Relative Abundance, and Diet of the Sand Shrimp ( Crangon septemspinosa Say) in the Sheepscot, Kennebec, and Damariscotta River Estuaries, Maine
Crangon septemspinosa Say, the sand shrimp, is an ecologically important and common inhabitant of coastal and estuarine waters of the western Atlantic, ranging from the Gulf of St. Lawrence to eastern Florida. Although sand shrimp are widely distributed, abundant, and considered to play an important...
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| Format: | Text |
| Language: | unknown |
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DigitalCommons@UMaine
2006
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| Online Access: | https://digitalcommons.library.umaine.edu/etd/1467 https://digitalcommons.library.umaine.edu/context/etd/article/2494/viewcontent/AlbrightJL2006.pdf |
| Summary: | Crangon septemspinosa Say, the sand shrimp, is an ecologically important and common inhabitant of coastal and estuarine waters of the western Atlantic, ranging from the Gulf of St. Lawrence to eastern Florida. Although sand shrimp are widely distributed, abundant, and considered to play an important role in the energetics of estuarine ecosystems, gaps in knowledge exist. To help fill this void, the present investigation was undertaken to describe the intertidal distribution and relative abundance of sand shrimp in relation to environmental variables in three adjacent estuarine systems, the Sheepscot, Kennebec, and Damariscotta Rivers, located along the mid-coast of Maine. Additionally, diet composition and feeding intensity of sand shrimp were determined by identifying prey items and examining the relative degree of gut fullness. Monthly sampling (June - October) using an epibenthic sled resulted in the collection of over 14,000 shrimp from wide ranges of temperature (9.4 - 25.9°C), salinity (3 - 34), and dissolved oxygen concentration (6.52 - 13.15 mg l-1). However, most large catches of sand shrimp were confined to narrower ranges of these environmental conditions. Maximum concentration and distribution of sand shrimp occurred when surface temperatures were between 10 and 18° C and salinities were ≥22 in the three estuaries. High shrimp abundance and widespread distribution in the estuaries occurred late in the sampling season as freshwater discharge declined and temperatures dropped below 20° C. Sand shrimp were differentially distributed according to sex and reproductive status. Ovigerous females and males were more abundant in the lower estuary where low temperatures and high salinities predominated. Penetration up the estuary by female and juvenile shrimp did not appear to be as limited. Overall, juvenile shrimp were a substantial portion of the total catch in each estuary despite their limited abundance and patchy distribution during the early part of the sampling season. Visual analysis of foregut ... |
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