A report on six cases of seagrass-associated gastric impaction in bottlenose dolphins (Tursiops sp.)

Marine debris such as plastic and other foreign objects (e.g., nylon fishing line, cigarette wrappers, metal bottle caps) are commonly found in odontocete stomachs (Walker and Coe 1990), but due to the often small amounts and diversity of the debris, the impact on animal health is unclear (Walker and Coe 1990, Laist 1997, Baird and Hooker 2000). Small quantities can however, have large effects if they are capable of intermittently or consistently blocking the pyloric outflow tract (e.g., Tarpley and Marwitz 1993, Stamper et al. 2006, Jacobsen et al. 2010) causing longterm malnutrition and death (Gomerˇci´c et al. 2006); either directly due to acute gastric rupture or complete pyloric obstruction, or indirectly as a result of chronic malnutrition due to partial/intermittent pyloric obstruction. Kastelein and Lavaleije (1992) documented the persistence of undigested algae in the forestomach of a harbor porpoise for at least 3 d. Several other odontocete species (e.g., bottlenose dolphins (Tursiops truncatus, e.g., McBride 1940), northern right whale dolphins (Lissodelphus borealis,Walker and Coe 1990), and spinner dolphins (Stenella longirostris, Trianni and Kessler 2002)) have been found to ingest marine plants, such as kelp (Egregia sp., Macrocystic pyrifera), seaweed (Fucus vesiculosus) or seagrass (Enhalus acroides, Haldule uninervis). However, death due to gastric impaction by marine plants (high densities of intertwined marine plant(s) preventing efficacious pyloric emptying and gastric evacuation (Santos et al. 2001)) is rarely reported (see McBride 1940, Trianni and Kessler 2002).