Faunal communities and habitat characteristics of the Big Bend seagrass meadows, 2009–2010.

Abstract

Seagrass meadows are important habitats that serve as nursery, feeding, and sheltering grounds for many marine species. In addition to the ecosystem functions and services they provide, seagrass habitats and associated fauna are commonly observed to have naturally high levels of heterogeneity, making them ideal for the study of ecological patterns and processes across multiple spatial scales. However, seagrass systems worldwide have undergone sharp declines in coverage and increased levels of fragmentation at both local and regional spatial scales, thus compromising their ecological functions and services and reducing their value as unaltered marine systems in which to conduct ecological studies. Covering nearly 3000 km2, the seagrass meadows of the Big Bend region in the eastern Gulf of Mexico represents one of the largest in the world, and given its separation from human population centers and coastal development, is also considered to be one of the most intact and least disturbed. The objective of our study was to provide the first region‐wide characterization of the habitats and faunal communities in seagrass meadows of the Big Bend. This two‐year study occurred in 2009 and 2010 during the summers when peak productivity in seagrass systems is highest. Sites were selected using a spatially balanced approach and sampling was conducted with beam trawls. A total of 170 sites were sampled, and all animals were identified to lowest taxonomic level possible, counted, and their sizes measured. Habitat characteristics were concurrently measured at both local (e.g., seagrass areal coverage and composition, volume of drift algae) and regional scales (e.g., latitude, type of adjacent coastal habitat).

Trophic niche size and overlap decreases with increasing ecosystem productivity

“…Sampling sites were chosen in a spatially-balanced manner (Stevens and Olsen 2004) that mimicked the distribution of seagrass, with the constraint that each site had a seagrass density >10% (Stallings et al 2015a). Detailed information on sampling protocols can be found in the published dataset (Stallings et al 2015a).…”

“…Sampling sites were chosen in a spatially-balanced manner (Stevens and Olsen 2004) that mimicked the distribution of seagrass, with the constraint that each site had a seagrass density >10% (Stallings et al 2015a). Detailed information on sampling protocols can be found in the published dataset (Stallings et al 2015a). Nekton at each site was sampled during the summer of 2009 using a beam trawl (mouth opening: 1.87 × 0.40 m, bag dimensions: 19 mm mesh with 3 mm mesh liner) towed on both sides of a 6.1 m research vessel for 2.5 min at a standard speed of 1.8-2.0 km h −1 (~85 m tow length).…”

“…Orthopristis chrysoptera (pigfish) and Lagodon rhomboides (pinfish) individuals, as well as representative samples of all available primary production channels, were collected via the beam trawl protocol described above and subjected to stable isotope analysis. Orthopristis chrysoptera and L. rhomboides represent two omnivorous, ubiquitous species native to this ecosystem (Stallings et al 2015a, Faletti et al 2019, that undergo ontogenetic shifts in their diet (Stoner 1980, Darcy 1983, and use resources over similar, small home ranges (Potthoff and Allen 2003). Epiphytes, seagrass detrius and benthic microalgae are known to make up a large portion of the diet of both species (Hansen 1969, Adams 1976, Stoner and Livingston 1984, both via direct consumption and via the consumption of benthic invertebrates relying on those production channels (Carr andAdams 1973, Stoner 1980).…”

Niche Differentiation and Prey Selectivity among Common Bottlenose Dolphins (Tursiops truncatus) Sighted in St. George Sound, Gulf of Mexico

“…George Sound is located in the Big Bed region of Florida which is home to the second largest contiguous seagrass meadow in Florida and subsequently one of the largest seagrass meadows in the world (Zieman and Zieman, 1989;Hale et al, 2004;Stallings and Koenig, 2011). Though it also remains one of the least disturbed seagrass meadows in the world (Stallings et al, 2015), the seagrass meadow in this region is considered "poor and declining" by Florida's Wildlife Legacy Initiative's Comprehensive Wildlife Conservation Strategy in part because increased nutrient loading has led to declining light levels and subsequent seagrass retreat from deeper waters (Hale et al, 2004). The dependence of the St. George Sound community on seagrass and associated epiphytes suggests that alteration of that seagrass habitat could have catastrophic consequences for this ecosystem (Zieman and Zieman, 1989).…”

Disentangling fine- and broad- scale effects of habitat on predator–prey interactions

“…Pinfish are an ecologically important species for several reasons. First, they are commonly the most abundant vertebrate found in 116 seagrass beds (Nelson et al, 2013;Stallings et al, 2015). Second, juveniles feed on a suite 117 of invertebrates influencing entire assemblages of benthic macrofauna (Young et al, 1976; 118 Young and Young, 1977;Nelson, 1978;Stoner, 1980;Nelson, 2002).…”