Effects of surrounding land use and water depth on seagrass dynamics relative to a catastrophic algal bloom

Abstract

Seagrasses are the foundation of many coastal ecosystems and are in global decline because of anthropogenic impacts. For the Indian River Lagoon (Florida, U.S.A.), we developed competing multistate statistical models to quantify how environmental factors (surrounding land use, water depth, and time [year]) influenced the variability of seagrass state dynamics from 2003 to 2014 while accounting for time-specific detection probabilities that quantified our ability to determine seagrass state at particular locations and times. We classified seagrass states (presence or absence) at 764 points with geographic information system maps for years when seagrass maps were available and with aerial photographs when seagrass maps were not available. We used 4 categories (all conservation, mostly conservation, mostly urban, urban) to describe surrounding land use within sections of lagoonal waters, usually demarcated by land features that constricted these waters. The best models predicted that surrounding land use, depth, and year would affect transition and detection probabilities. Sections of the lagoon bordered by urban areas had the least stable seagrass beds and lowest detection probabilities, especially after a catastrophic seagrass die-off linked to an algal bloom. Sections of the lagoon bordered by conservation lands had the most stable seagrass beds, which supports watershed conservation efforts. Our results show that a multistate approach can empirically estimate state-transition probabilities as functions of environmental factors while accounting for state-dependent differences in seagrass detection probabilities as part of the overall statistical inference procedure.

A human impact metric for coastal ecosystems with application to seagrass beds in Atlantic Canada

“…This is similar to bays in Gulf NB+NS but is much higher than PEI where only 11% of bays have no coastal land protection. Seagrass beds bordered by land managed for conservation purposes usually have higher temporal stability than beds associated with unprotected land (Breininger et al 2016). Not surprisingly, our results show that coastal land protection at the bay-scale correlates well with the extent of riparian land alteration adjacent to seagrass beds i.e.…”

Sampling rare and elusive species: Florida east coast diamondback terrapin population abundance

“…One possible explanation is that predatory river otters (Lontra canadensis) and alligators (Alligator mississippiensis) patrol along the water's edge and the shallowest waters are not the best areas for seagrass where there is much potential terrapin prey (Breininger et al 2016). One possible explanation is that predatory river otters (Lontra canadensis) and alligators (Alligator mississippiensis) patrol along the water's edge and the shallowest waters are not the best areas for seagrass where there is much potential terrapin prey (Breininger et al 2016).…”

“…We observed more terrapins in deeper waters in contrast to our a priori predictions of terrapins preferring shallow waters along mangrove edges. One possible explanation is that predatory river otters (Lontra canadensis) and alligators (Alligator mississippiensis) patrol along the water's edge and the shallowest waters are not the best areas for seagrass where there is much potential terrapin prey (Breininger et al 2016). We initially searched salt marsh and mangrove edges when trying to locate terrapins while accidentally noticing terrapins behind us in open water lagoons and we do not know if other terrapin researchers had a similar search image leading to less frequent terrapin sittings.…”

“…The Indian River lagoonal system makes up much of the subspecies' range along the east central Florida coast, being about 251 km long and usually <8 km wide having shallow lagoons (mostly 0.0-3.0 m) with little tidal influence, but high biological diversity (Swain et al 1995). The IRL open water area is undergoing harmful algae blooms, seagrass die-offs, and fish kills (Breininger et al 2016, Tiling and Proffitt 2017, Hanisak and Davis 2018 that might affect terrapins. Most of the IRL shoreline has become urbanized since the 1950s except for large barrier island complexes (>60,000 ha) dedicated to the space program and conservation (Duncan et al 2004).…”

Transport of Nano- and Microplastic through Unsaturated Porous Media from Sewage Sludge Application

“…Eutrophication of coastal lagoons is a serious problem worldwide (see e.g., the cases of Ria Formosa, Portugal, Newton et al, 2003;Maryland, US, Boynton et al, 1996;Sacca de Goro, Italy, Naidi and Viaroli, 2002; Lake Shinji, Japan, Nakamura and Kerciku, 2000;Lagune de Thau, France, Mesnage and Picot, 1995; Rhode Island, US, Lee and Olsen, 1985). The input of nutrients to coastal lagoons contributes dramatically to algal blooms (Breininger et al, 2017) that can reach levels of toxicity to wildlife and humans. Thus, eutrophication also causes negative impacts on tourism and, correspondingly, on the economy (McCrakin et al, 2017).…”