Helminths of Three Species of Goby (Pisces: Gobiidae) from Mission Bay, San Diego

Pteria sterna is an eastern Pacific pearl oyster of commercial value from Peru to central Baja California, Mexico. The continuous presence of this species in San Diego for a decade is unique as it is approximately 600 km north of the expected range for the species. A minimum of three generations are present in Mission Bay at any point in time and the preferred substrate for attachment are gorgonian corals. The species is also found off shore in cooler water. The continued presence of this oyster raises the question as to the status of this population; is it a permanent range extension or simply a transient population and what has changed that allowed its continued presence?

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Survival and re-establishment of vegetative fragments of eelgrass (Zostera marina)

Canadian Journal of Botany ◽

10.1139/b96-191 ◽

1996 ◽

Vol 74 (10) ◽

pp. 1584-1590 ◽

Cited By ~ 35

Author(s):

Patrick J. Ewanchuk ◽

Susan L. Williams

Keyword(s):

Population Growth ◽

Water Column ◽

Asexual Reproduction ◽

Aquatic Plants ◽

Zostera Marina ◽

San Diego ◽

Potential Contribution ◽

Mission Bay ◽

Survival And Growth ◽

Eelgrass Beds

Vegetative fragmentation of clonal aquatic plants is considered a form of asexual reproduction. Although vegetative fragmentation of eelgrass (Zostera marina L.) is considered a mode of asexual reproduction and dispersal, no data exist to evaluate the potential contribution of fragments (rhizomes with meristems and green leaf shoots) to eelgrass populations. We estimated (i) the size of the fragment population relative to the size of adjacent eelgrass populations, and (ii) the potential for fragments to re-establish in eelgrass beds in Mission Bay, San Diego, Calif. We surveyed the abundance of fragments on adjacent beaches and determined the survival and growth of detached fragments and of fragments re-established in eelgrass beds after varying time spent in the water column. Although vegetative fragments occurred throughout the year, but mostly in winter, they represented a loss of <4% of the leaf shoots in adjacent eelgrass populations. Only 60% of the fragments survived in the water column after 6 weeks, and growth and survivorship of re-established fragments declined with time spent in the water column. Thus, fragmentation represents a small net loss to the eelgrass beds studied and is not a common recruitment mechanism. This result does not support the hypothesis that asexual reproduction in the form of vegetative fragments contributes to eelgrass population growth. Because successful re-establishment is improbable, vegetative fragments also are not likely to contribute substantially to eelgrass dispersal, at least in Mission Bay. Keywords: eelgrass, asexual reproduction, clone fragmentation, Zostera marina.

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CASE HISTORY OF MISSION BAY INLET SAN DIEGO, CALIFORNIA

Coastal Engineering Proceedings ◽

10.9753/icce.v13.40 ◽

1972 ◽

Vol 1 (13) ◽

pp. 40 ◽

Cited By ~ 1

Author(s):

William J. Herron

Keyword(s):

Los Angeles ◽

Case History ◽

San Diego ◽

Aerial Photographs ◽

Army Corps ◽

Army Corps Of Engineers ◽

Littoral Drift ◽

Cross Sectional ◽

Corps Of Engineers ◽

Mission Bay

The Mission Bay Inlet was designed as a "Non-Scouring" entrance channel by the Los Angeles District, Corps of Engineers, in 1946. Construction of the inlet was completed in 1959 and the entire project was completed in 1963. A channel with over twice the cross sectional area required by the "O'Brien" equation was developed to reduce the average cross-sectional tidal currents to less than two feet per second. The design depth of -20 feet MLLW eliminated bottom movement induced by wave action- except during the most severe storms. The jetties are sealed to the +4 foot elevation and extend to the -25 foot depth almost entirely eliminating the intrusion of littoral drift. The channel has shoaled at a rate of less than 20,000 cubic yards per year since final dredging in 1959) indicating the soundness of this concept. This case history was prepared under contract to the Coastal Engineering Research Center, U. S. Army, Corps of Engineers, and project data and aerial photographs were obtained from the Los Angeles District, U. S. Army, Corps of Engineers, and the City of San Diego.

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