SeagrassNet monitoring across the Americas: case studies of seagrass decline

Abstract

Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land–sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world's oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1–2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action.

Cover versus recovery: Contrasting responses of two indicators in seagrass beds

“…3): when LAI standing increases, relative recovery decreases. This observation seems contradictory with the concept behind the basic monitoring approaches looking at biomass or cover to estimate a seagrass meadow resilience and health status (Orth and Moore, 1988;McKenzie et al, 2003;Short et al, 2006) and the concept of seagrass conservation. Seagrass meadows with a high cover, relating to a healthy status, are supposed to have higher tolerance to stress.…”

“…For most monitoring programs like seagrass watch or seagrass net, seagrass density or percent ground cover are commonly used indicators to evaluate a meadow status along transects or quadrats (McKenzie et al, 2003;Duarte et al, 2004;Short et al, 2006). With these measurements, seagrass status can be evaluated by comparing cover maps over defined periods of time and to observe the evolution and status of the meadow (i.e.…”

“…healthy or in decline). These monitoring programs also use environmental parameters such as water and sediment quality in combination with seagrass measurements to infer the causes of changes in seagrass cover and distribution (Duarte et al, 2004;Short et al, 2006;Neckles et al, 2012).…”

Classifying Ecological Quality and Integrity of Estuaries

“…, DOI: 10.1016/B978-0-12-374711-2.00 1 10 Treatise on Estuarine and Coastal Science, 162, 9-1 125-Mediterranean Sea, P. oceanica beds cover between 25 000 and 50 000 km 2 of the coastal areas corresponding to 25% of the sea bottom at depths between 0 and 40 m. Additional details on seagrasses from North and South America can be found in Short et al (2006) and SeagrassNet website.…”

“…Hence, established in 2001, SeagrassNet is a monitoring program for seagrasses worldwide, which uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and envir onmental variables (Short et al, 2006). This program is designed to statistically detect change over a relatively short time frame (1-2 years) through quarterly monitoring of per manent plots.…”