Ecological evaluation of a marine protected area network: a progressive‐change BACIPS approach

Abstract

Marine protected area (MPA) networks, with varying degrees of protection and use, can be useful tools to achieve both conservation and fisheries management benefits. Assessing whether MPA networks meet their objectives requires data from Before the establishment of the network to better discern natural spatiotemporal variation and preexisting differences from the response to protection. Here, we use a Progressive‐Change BACIPS approach to assess the ecological effects of a network of five fully and three moderately protected MPAs on fish communities in two coral reef habitats (lagoon and fore reef) based on a time series of data collected five times (over three years) Before and 12 times (over nine years) After the network's establishment on the island of Moorea, French Polynesia. At the network scale, on the fore reef, density and biomass of harvested fishes increased by 19.3% and 24.8%, respectively, in protected areas relative to control fished areas. Fully protected areas provided greater ecological benefits than moderately protected areas. In the lagoon, density and biomass of harvested fishes increased, but only the 31% increase in biomass in fully protected MPAs was significant. Non‐harvested fishes did not respond to protection in any of the habitats. We propose that these responses to protection were small, relative to other MPA assessments, due to limited compliance and weak surveillance, although other factors such as the occurrence of a crown‐of‐thorns starfish outbreak and a cyclone after the network was established may also have impeded the ability of the network to provide benefits. Our results highlight the importance of using fully protected MPAs over moderately protected MPAs to achieve conservation objectives, even in complex social–ecological settings, but also stress the need to monitor effects and adapt management based on ongoing assessments.

Same species, different prerequisites: investigating body condition and foraging success in young reef sharks between an atoll and an island system

“…Prey resources and their caloric value may deteriorate in nearshore areas with substantial anthropogenic impacts 28,49 . Indeed, the abundance of small reef-associated teleosts is declining through large-scale habitat degradation 27,50 , and artisanal fishing 51 .…”

Increased connectivity and depth improve the effectiveness of marine reserves

“…In cases where fish were absent either inside or outside the reserve (i.e. zero values), one individual fish and the average (mean) weight of an individual fish was added to one replicate (inside and outside the reserve) to allow calculation of the log ratio for abundance and biomass, following Thiault et al (2019). Effect sizes were calculated as follows:where E m , i is the log response ratio for each marine reserve i based on the metric m (abundance or biomass) and and are the mean of each metric m in protected ( P ) and fished ( F ) areas respectively.…”

Evaluating Impact Using Time-Series Data

“…In ecological impact evaluation, trends have only very recently been included. Thiault et al [29,30] introduced the 'Progressive Change BACIPS' approach in 2017, as an extension of BACIPS that considers trends in the 'after' period, but still assumes no change through time in the 'before' period. Chevalier et al [9] addressed this by considering trends and averages both before and after, and also introduced 'CI-measures', which further quantify the nature of impact in a BACI framework [31].…”