Inside Marine Protected Areas Research Articles

Community-wide effects of protection reveal insights into marine protected area effectiveness for reef fish

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 620:99-117 (2019) - DOI: https://doi.org/10.3354/meps12970 Community-wide effects of protection reveal insights into marine protected area effectiveness for reef fish E. R. Heyns-Veale1,2,*, A. T. F. Bernard2,3, A. Götz1,4, B. Q. Mann5, J. Q. Maggs5, M. K. S. Smith6 1South African Environmental Observation Network (SAEON), Elwandle Node, NMMU Ocean Sciences Campus, 4 Gomery Avenue, Summerstrand, Port Elizabeth, 6031, South Africa 2South African Institute for Aquatic Biodiversity (SAIAB), Somerset Street, Makhanda 6140, South Africa 3Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa 4Zoology Department, Nelson Mandela University, Port Elizabeth 6031, South Africa 5Oceanographic Research Institute, PO Box 10712, Marine Parade, Durban 4056, South Africa 6Rondevlei Scientific Services, South African National Parks, Sedgefield 6573, South Africa *Corresponding author: elodieheyns@gmail.com ABSTRACT: Marine protected areas (MPAs) are not designed the same, nor are they equally effective. Efficacy of MPAs is frequently gauged by measuring the direct ecological responses of fish communities. However measuring the indirect, or knock-on effects from protection can provide additional insight into MPA effectiveness at the community level. Here we applied trait-based and community analyses to investigate MPA effectiveness by evaluating both direct and indirect effects of protection on fish assemblages using baited remote underwater stereo-video data from inside and outside 5 no-take MPAs along the South African coastline. The trait-based analyses indicated the presence of a significant overall direct effect (increased abundance of mature individuals targeted by fisheries) and indirect effects (reduction of the abundance of species not targeted by fisheries) inside MPAs, and highlighted that fish maturity is an essential trait to incorporate when assessing direct effects of protection. However, investigation of the species data of the individual MPAs showed positive reserve effects at the community level (both direct and indirect effects) in only 3 MPAs. For the most part these results conform with current theories on the factors that contribute to MPA effectiveness. Yet, one old, large and isolated no-take MPA showed no direct effects of protection, which is attributed to the lack of adequate offshore reef habitat throughout this MPA. While these results support the value of MPAs as ecosystem management tools, they highlight the need for appropriate site selection when designing MPAs. KEY WORDS: MPA effectiveness · NEOLI · Stereo-BRUVs · Functional entities · Life-stage · Ecological isolation Full text in pdf format Supplementary material PreviousNextCite this article as: Heyns-Veale ER, Bernard ATF, Götz A, Mann BQ, Maggs JQ, Smith MKS (2019) Community-wide effects of protection reveal insights into marine protected area effectiveness for reef fish. Mar Ecol Prog Ser 620:99-117. https://doi.org/10.3354/meps12970 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 620. Online publication date: June 18, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Enhancing fish Underwater Visual Census to move forward assessment of fish assemblages: An application in three Mediterranean Marine Protected Areas.

Monitoring fish assemblages is needed to assess whether Marine Protected Areas (MPAs) are meeting their conservation and fisheries management goals, as it allows one to track the progress of recovery of exploited species and associated communities. Underwater Visual Census techniques (UVC) are used to monitor fish assemblages in MPAs. UVCs should be adapted to fish abundance, body-size and behaviour, which can strongly affect fish detectability. In Mediterranean subtidal habitats, however, UVC strip transects of one surface area (25x5 m2) are commonly used to survey the whole fish assemblage, from large shy fish to small crypto-benthic fish. Most high trophic level predators (HTLPs) are large shy fish which rarely swim close to divers and, consequently, their abundance may be under-estimated with commonly used transects. Here, we propose an improvement to traditional transect surveys to better account for differences in behaviour among and within species. First, we compared the effectiveness of combining two transect surface areas (large: 35x20 m2; medium: 25x5 m2) in quantifying large, shy fish within and outside Mediterranean MPAs. We identified species-specific body-size thresholds defining a smaller and a larger size class better sampled by medium and large transects respectively. Combining large and medium transects provided more accurate biomass and species richness estimates for large, shy species than using medium transects alone. We thus combined the new approach with two other transect surface areas commonly used to survey crypto-benthic (10x1 m2) and necto-benthic (25x5 m2) species in order to assess how effectively MPAs protection the whole fish assemblage. We verified that MPAs offer significant protection for HTLPs, their response in terms of biomass and density increase in MPAs was always higher in magnitude than other functional groups. Inside MPAs, the contribution of HTLP reached >25% of total fish biomass, against < 2% outside MPAs. Surveys with multiple transect surface areas allow for a more realistic assessment of the structure of the whole fish assemblage and better assessment of potential recovery of HTLPs within reserves of HTLP.

Evaluating the importance of Marine Protected Areas for the conservation of hawksbill turtles Eretmochelys imbricata nesting in the Dominican Republic

Understanding spatial and temporal habitat-use patterns to protect both foraging and breeding grounds of species of concern is crucial for successful conservation. Saona Island in Del Este National Park (DENP), south-eastern Dominican Republic (DR), hosts the only major hawksbill (Eretmochelys imbricata) nesting area in the DR (100 nests yr �1 , SD = 8.4, range = 93�111), with the population having been critically reduced through hunting. We satellite tracked 9 female hawksbill turtles, and present analyses of their core-use areas with respect to Marine Protected Areas (MPAs) in both their internesting and foraging areas. Kernel utilization distribu- tions indicated that during the internesting period all turtles remained close to their nesting beaches in small home ranges in the territorial waters of the DR, mostly over the continental shelf (<200 m depth). Common core-use areas were located inside the DENP, and 82.7% of all locations were within the DENP. In foraging areas, only 23% of locations were inside MPAs, either in waters of the DR or in waters of the Bahamas, Nicaragua and Honduras. Our results highlight that the protected areas of the DR are vital for hawksbill conservation, and the enforcement of existing leg- islation governing protected areas in the country is crucial. The present study also corroborates that the waters off Nicaragua and Honduras are exceptionally important foraging areas for hawksbills in the Caribbean, showing the turtle's vulnerability in these waters.

Silent fish surveys: bubble‐free diving highlights inaccuracies associated with SCUBA‐based surveys in heavily fished areas

Summary Underwater visual census (UVC) using SCUBA is a commonly used method for assessing reef fish communities. Evidence suggests, however, that fish avoid divers due to the sound of bubbles produced by open‐circuit SCUBA, and avoidance behaviour is more pronounced as fishing pressure increases. Despite the potential for producing biased counts and conclusions, these behavioural effects have rarely been quantified, especially when assessing the effectiveness of marine protected areas (MPAs). To test the magnitude of avoidance behaviour, we surveyed fish populations inside and outside two MPAs in Guam, using two diving systems: standard open‐circuit (OC) SCUBA and a closed‐circuit rebreather (CCR) that produces no bubbles. Data were collected using a diver‐operated stereo‐video system (stereo‐DOV), which provided counts of relative abundance, measures of fish length and the minimum approach distance of the diver to a fish. Inside MPAs, fish surveys conducted with CCR recorded similar community metrics to fish surveys conducted with conventional OC SCUBA. In contrast, outside the MPAs, the bubble‐free diving system recorded 48% more species and up to 260% greater fish abundance. These differences reflected the ability of a diver wearing the silent CCR unit to sample the larger, most heavily targeted species that are shy of divers in fished areas. This difference was also large enough to change some results from ‘reject’ to ‘accept’ the null hypothesis of ‘no significant differences exist between fished and protected areas’. The use of CCR for fish surveys clearly minimizes behavioural biases associated with fish avoiding open‐circuit SCUBA divers. We recommend the use of this bubble‐free diving system for surveys assessing reef fish populations, especially in areas where fish are heavily targeted by spearfishing. If fish behaviour is not accounted for, surveys using SCUBA could result in erroneous conclusions when comparing fished and protected areas. While the behaviour of fish towards divers is rarely mentioned in conclusions from studies using UVC, it is an important source of bias that should be acknowledged and minimized where possible.

Herbivorous fishes and the potential of Caribbean marine reserves to preserve coral reef ecosystems

Abstract The development of macroalgae to the detriment of corals is now one of the major threats to coral reefs. Herbivorous fishes are partly responsible for algal regulation on coral reefs and their overexploitation favours the shift from scleractinian coral‐dominated systems towards macroalgae‐dominated systems. Marine protected areas (MPAs) that have been established worldwide may benefit coral reefs through the maintenance of high densities of herbivorous fishes which regulate algal growth. The paper assesses whether small MPAs in the Caribbean are able to enhance herbivorous fish stock and by controlling macroalgae help to maintain reef ecosystems. A visual census using band‐transects was undertaken around Guadeloupe island where marine reserves have been in place since 1979. The effects of MPAs on both benthic communities and herbivorous fishes are examined. Inside MPAs, herbivorous fish biomass was almost twice as high as outside MPAs and macroalgal cover was significantly lower. Fish size class distributions revealed that large individuals occurred mainly inside MPAs and that few male individuals were found outside MPAs. Copyright © 2010 John Wiley &amp; Sons, Ltd.