Differences of density and diversity of diurnal caridean shrimps between seagrass meadows of the invasive species Halophila stipulacea and the native species Thalassia testudinum
Abstract
Background. The invasive tropical seagrass Halophila stipulacea was reported for the first time in north Puerto Rico in 2017 and it has spread throughout the island since. It differs significantly from the native seagrass species Thalassia testudinum in terms of nutrient composition and morphology, representing a different habitat for small invertebrates.
Methods. To evaluate the effect of the arrival of the seagrass species Halophila stipulacea on seagrass-associated invertebrates, caridean shrimps were sampled in meadows dominated by the native seagrass Thalassia testudinum and the invasive Halophila stipulacea at three zones in southwestern Puerto Rico. Samples were collected in triplicate 10-meter transects during two sampling periods over a span of three months during summer 2024 using a 1.2-mm mesh push net.
Results. Total caridean abundance was significantly higher (p < 0.01) in Halophila stipulacea meadows than in Thalassia testudinum meadows. Eight genera of caridean shrimps were collected. However, 82.19% of the total abundance (N = 3,203) was accounted for by four genera. Hippolyte sp. (28.11%), Palaemonella sp. (26.47%), and Thor sp. (11.13%) were more abundant in H. stipulacea beds while Latreutes fucorum (15.98%) was more abundant in T. testudinum beds. The genus with the consistently highest overall abundance was Hippolyte spp. in both seagrass species, followed by Palaemonella sp. or Latreutes fucorum in H. stipulacea and T. testudinum, respectively. On the other hand, Leander tenuicornis was the least abundant species overall, followed by Tozeuma carolinense, which was found only in T. testudinum in one zone.