Recruitment of estuarine dependent species of commercial and recreational importance through the Aransas Ship Channel

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2018-12

Authors

Buskey, Edward J.

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Several species of shellfish and finfish of commercial or recreational importance in the Nueces and Mission-Aransas Estuaries possess life history patterns that are dependent upon estuaries, whereby juvenile members of these species live and mature in these estuary “nurseries”, then migrate to the Gulf of Mexico as reproductive adults, releasing their eggs and planktonic larvae in the open ocean. The larvae feed, grow and develop in the Gulf of Mexico, but must return back to these estuaries to complete their life cycle. These planktonic larvae possess weak swimming skills and are too small to migrate directly back into the estuaries under their own power, so they must depend on hydrodynamic and environmental signals to selectively ride tidal and meteorologically driven currents back into the estuaries and avoid being flushed back out when these currents reverse. Tides are relatively small in the Northwestern Gulf of Mexico, and especially for estuaries in South Texas with little inflow of freshwater, meteorological forcing over times scales of several days play a significant role in estuarine-shelf water exchanges (Smith 1978). The Aransas Pass connecting the Nueces and Mission-Aransas Estuaries to the Gulf of Mexico was originally a shallow inlet between Mustang and San Jose Islands and it has been dredged to allow access for ocean-going vessels to the Port of Corpus Christi. This deeper channel now delivers most of the water exchange between the Nueces/Mission-Aransas Estuaries and the Gulf of Mexico, which has reduced the flow through other shallow historical passes between these estuaries and the Gulf, causing them to fill in with sediments and close unless maintained through dredging (e.g. Fish Pass, Cedar Bayou). As a result of historical passes closing due to the already permitted deepening of the Aransas Pass, this channel is now the main route available for larvae to recruit from the Gulf to local estuaries. It is unclear how additional alterations to the depth of the Aransas Pass and adjacent waters will alter hydrodynamics in this channel, or other remaining channels, and affect the recruitment of estuarine dependent larvae. Below are several examples of important estuarine species that could be impacted

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