Long‐term stability of eelgrass fish assemblages in two highly developed coastal estuaries

Abstract

Changes in fish assemblages were tracked in representative eelgrass (Zostera marina L.) beds within two estuaries on the urbanised coast of southern California, USA, San Diego Bay and Mission Bay, from 1987 to 2010. Assemblages were sampled twice yearly (spring and summer) at day and night using beach seines. Assemblage stability was examined over time along with changes in assemblage structure across time of day and season, including the influence of temporally variable abiotic variables. Only the occasionally occurring fish, those present in <70% of samples, in Mission Bay appeared to be shifting to a new assemblage. Although season and sampling time significantly affected assemblages, correlations with abiotic factors were low. Given the long history of urban development of these estuaries, community shifts may have occurred prior to the onset of sampling, giving the appearance of stability. Alternatively, eelgrass habitat may be providing a refuge from long‐term disturbances.

Porewater Carbonate Chemistry Dynamics in a Temperate and a Subtropical Seagrass System

“…2). It is a semi-enclosed but well-mixed, mesotidal estuary spanning 17.1 km 2 with extensive anthropogenic modifications including artificial islands and beaches (Obaza et al 2015). Due to low freshwater inputs and high evaporation rates, Mission Bay is typically slightly hypersaline (S ≈ 34-36) compared to open ocean water (Largier et al 1997).…”

What is the impact on fish recruitment of anthropogenic physical and structural habitat change in shallow nearshore areas in temperate systems? A systematic review protocol

“…Today, controversies remain as to what the primary causes of larval and juvenile fish declines are; whether anthropogenic alteration or loss of nursery coastal habitats are responsible for the declines; to what extent various habitat restoration approaches are effective; and what, if anything, can be done to reverse the declines of fish stocks [5,12]. However, recently, researchers have focused their attention on the links between anthropogenic pressures and fish recruitment success, and the accumulation of new data (see for example: [31][32][33][34][35]) suggests that a systematic review on the topic could find relevant evidence to support management actions directed towards maintaining the function of shallow nearshore and coastal areas and the conservation or restoration of fish populations.…”

A continuous involvement of stakeholders promotes the ecosystem approach to fisheries in the 8-fjords area on the Swedish west coast

“…Fry and juvenile fish can use eelgrass beds as feeding grounds and as protection against predators. Eelgrass beds can thus widen the bottleneck for survival that the fry and juvenile stages and their exposure to food constraints and predators comprise (Obaza et al, 2015).…”