Tidewater Gobies occupy cool (16-25oC) brackish water in lagoons created by coastal streams. Gobies favor salinities less than 10 ppt but may survive at levels up to 40 ppt. The lagoons may become isolated in dry summer months threatening gobies when the water is not well-oxygenated. In contrast high flows and tidal environments can have a greater negative affect on goby populations than predators. Favorable habitat includes shallow open water with emergent vegetation. Aquatic vegetation is important for protection and presumably feeding, while open water is important to breeding. Gobies are found in the greatest population densities within emergent or submerged vegetation. Juvenile Tidewater Gobies may move as far as 12 km and share habitat with a variety of fish species depending upon their distribution. Gobies feed by capturing prey in one of three ways: sediment sifting, midwater capture, or plucking individuals from the bottom. They feed opportunistically and primary food sources change throughout the year. Prey items include benthic organisms such as aquatic insects and small crustaceans. Adults feed primarily at dawn and dusk while juvenile gobies feed around the clock. Tidewater Gobies rarely live more than a year and breeding may occur multiple times during a period of several months. Spawning may occur year round but it is less frequent in December through March. Female gobies produce an average of 15 to 1,100 eggs per spawn, and may spawn up to 12 times over the course of several months. Gobies are capable of rapid re-colonization and rebound from low numbers quickly. Spawning among Tidewater Gobies is sometimes preceded by elaborate courtship and competitive behavior. Males and females typically only breed with one member of the opposite sex per spawning session. Male gobies create burrows where one female enters for 1 - 3 days. Fertilized eggs are attached to a burrow wall and left by the females. Male gobies guard and attend to the embryos for 9-11 days. Once the embryos hatch they take on a planktonic form and the male goby abandons the young. Young gobies become benthic again when they reach a standard length of 16-18 mm.
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