Quantification and classification of the main environmental impacts on a Halodule wrightii seagrass meadow on a tropical island in northeastern Brazil

Abstract

Multiple stress mechanisms have caused a worldwide decrease in seagrasses, which are vulnerable to environmental and/or anthropogenic pressure. The loss of seagrass meadows of Halodule wrightii is reported for the littoral of Itamaracá Island (Northeastern Brazil). The present study identified the main anthropogenic factors that negatively influenced over the abundance and distribution of seagrass meadows between July and September 2007 at the Jaguaribe and Pilar Beaches, Eastern littoral of Itamaracá. Anthropogenic impact included the discharge of untreated sewage through fluvial channels, urban and commercial development along the coast, the anchoring of motorized and non-motorized boats, diverse fishing techniques and the dumping of solid waste. The data indicates that the Pilar is an environment with a higher impact index (71.43%) when compared with the Jaguaribe (57.14%), standing out the number of boats with a central motor, the total number of boats, the presence of shellfish gatherers and coastal urban development. The present study reinforces the need for defining management and conservation measures for this ecosystem, which has high ecological and economic value.

Effect of trampling and digging from shellfishing on <em>Zostera noltei</em> (Zosteraceae) intertidal seagrass beds

“…Seagrass beds are among the most valuable ecosystems in the world (Costanza et al 2014), but they are also among those most affected by human activities (Pitanga et al 2012) and have decreased significantly in recent decades (Short and WyllieEcheverria 2000), now occupying a much lower area than in the past (Short et al 2011). This reduction in coverage has been related to direct and indirect human activities (Hastings et al 1995, Baden et al 2003, along with global climate change .…”

“…Among the several pressures and impacts affecting seagrasses, those occurring in the intertidal zone are mainly caused by human presence in general (Eckrich and Holmquist 2000, Pitanga et al 2012), and by shellfish activity for human consumption and for live bait in particular (Boese 2002, Dolch and Reise 2010, Nordlund and Gullström 2013.…”

Seagrass and Submerged Aquatic Vegetation (VAS) Habitats off the Coast of Brazil: state of knowledge, conservation and main threats

“…By comparing historical observations and studies (of the 1970s and 1980s) with recent monitoring and experimental studies (of the 1990s and 2000s), major seagrass changes and losses (up to 50% losses) have been detected, mainly surrounding metropolitan areas such as Recife ALVES, 2002;PITANGA, 2012), Rio de Janeiro, Búzios, Cabo Frio (CREED, 2000a;CREED, 2003), Santos Bay (E. C. OLIVEIRA, Pers. Comm.)…”

“…In the northeast region, anthropogenic and natural impacts on seagrasses have been qualified and quantified along the Pernambuco coast, indicating significant changes in the meadows' extension and abundances (PITANGA et al, 2012). The losses have been attributed to impacts such as continental discharge, urban development, boating activity, destructive fishing techniques and the dumping of solid waste (PITANGA et al, 2012).…”

“…The losses have been attributed to impacts such as continental discharge, urban development, boating activity, destructive fishing techniques and the dumping of solid waste (PITANGA et al, 2012). While some losses have been attributed to natural causes or extreme events , many meadows have been reduced due to seagrass harvesting to feed captive manatees (MAGALHÃES; ALVES, 2002).…”