Reef manta rays Mobula alfredi are large, filter-feeding elasmobranchs known to aggregate in coastal areas and island archipelagos. Effective spatial conservation strategies, such as marine protected areas (MPAs), for this mobile marine species rely on a comprehensive understanding of movement behavior. To better understand movement patterns, we externally deployed 58 acoustic tags on reef mantas at the Palmyra Atoll National Wildlife Refuge and monitored the presence of mantas on an extensive array of acoustic receivers (n = 85) for close to a decade. We documented an average maximum residency rate of 88% as well as consistent use of all 4 primary habitat types at Palmyra-the lagoon system, reef terrace, forereef, and channel. Notably, the highest rates of detection were recorded in the nutrient rich lagoon habitats (69% of detections). Manta movements displayed a diel structure, with a preference for the forereef, reef terrace, and channel during daylight hours, and the lagoon at night. We also found bimodal peaks of activity during new and full moons. In addition, detections around the atoll increased during the cooler periods of fall and winter. Our findings demonstrate that the no-fishing regulations at Palmyra Atoll are an effective spatial management strategy for this resident population of reef mantas and indicate that reef ecosystems in remote locations may be well-suited for designation as MPAs, offering protection for threatened elasmobranch species.

Marine Protected Areas (MPAs) have been implemented globally as a conservation tool to improve the health and function of marine ecosystems. Research has focused on assessing MPA effectiveness, however certain habitats and communities are often avoided because they are difficult or expensive to monitor. Mesophotic (30-100m) rocky reef fish communities are a valuable commercial and recreational resource that is highly targeted but often overlooked in monitoring due to depth restricted sampling. We used two MPAs in California’s statewide protection network, along with parried reference sites, to test how protection status along with environmental conditions influenced the abundance and biomass of three highly targeted species with varying life histories and habitat preferences. Depth and habitat were strong predictors for all groups; ocean whitefish ( Caulolatilus princeps ), California sheephead ( Semicossyphus pulcher ), and targeted rockfish ( Sebastes spp ). The pattern of these effects however, differed between the species groups and the influence of protection was mixed. This work highlights how species with high habitat affinities benefit differently from protection, as a function of depth and habitat representation within the MPA/reference pair. To accurately evaluate MPAs, and the network as a whole, researchers must recognize organism-habitat relationships and incorporate them when assessing conservation efforts. ### Competing Interest Statement The authors have declared no competing interest.

Marine protected areas (MPAs) have become a popular tool utilised across global oceans to achieve a variety of conservation goals. Because the reasons for MPA implementation can differ, it is imperative that resource managers design and execute management strategies that allow them to effectively assess MPA performance relative to the goals they set.We compared three MPA monitoring techniques commonly utilised to survey groundfish populations across different depth strata of temperate rocky reef habitat: underwater visual census (0-20 m), scientific hook and line fishing (10-50 m) and baited remote underwater video (30-100 m). We compared the strength and direction of standardised metrics, including response ratios, diversity indices and community structure, examining results through the lens of MPA performance.While each of our monitoring techniques detected similar MPA effects on groundfish biomass and density aggregated across species, MPA effects for individual species varied across methods.Each technique was shown to survey distinct groundfish community assemblages with varying levels of species diversity and richness.Synthesis and applications. While each technique was found to measure similar general trends in marine protected area (MPA) performance over time, we found compelling evidence that the utilization of multiple techniques allows managers to create the most comprehensive, effective and inclusive MPA monitoring regimes.

Ecosystems are changing at alarming rates because of climate change and a wide variety of other anthropogenic stressors. These stressors have the potential to cause phase shifts to less productive ecosystems. A major challenge for ecologists is to identify ecosystem attributes that enhance resilience and can buffer systems from shifts to less desirable alternative states. In this study, we used the Northern Channel Islands, California, as a model kelp forest ecosystem that had been perturbed from the loss of an important sea star predator due to a sea star wasting disease. To determine the mechanisms that prevent phase shifts from productive kelp forests to less productive urchin barrens, we compared pre- and postdisease predator assemblages as predictors of purple urchin densities. We found that prior to the onset of the disease outbreak, the sunflower sea star exerted strong predation pressures and was able to suppress purple urchin populations effectively. After the disease outbreak, which functionally extirpated the sunflower star, we found that the ecosystem response-urchin and algal abundances-depended on the abundance and/or size of remaining predator species. Inside Marine Protected Areas (MPAs), the large numbers and sizes of other urchin predators suppressed purple urchin populations resulting in kelp and understory algal growth. Outside of the MPAs, where these alternative urchin predators are fished, less abundant, and smaller, urchin populations grew dramatically in the absence of sunflower stars resulting in less kelp at these locations. Our results demonstrate that protected trophic redundancy inside MPAs creates a net of stability that could limit kelp forest ecosystem phase shifts to less desirable, alternative states when perturbed. This highlights the importance of harboring diversity and managing predator guilds.

The Islas Marías Biosphere Reserve, made up of 4 islands in Pacific waters off central Mexico, supports a large diversity of marine life. However, scientific research was restricted for decades by the occupation of Isla María Madre by the Federal Penitentiary Colony of Mexico from 1905 to 2019. Aside from a list of coastal fish species published in 2011, little has been published about the fish biodiversity in the area. While the limited access to the archipelago may have acted as a de-facto marine reserve, there is evidence that fishing continued both legally for the benefit of the colony and illegally by trespassing vessels. In order to establish baseline ecological data for future conservation planning, we used baited remote underwater video (BRUV) surveys at all 4 islands during 3 expeditions to the archipelago in 2018. A total of 131 BRUV surveys representing ~150 h of footage were analyzed to create the most current compilation of species and abundance data on coastal marine fishes at Islas Marías. Ninety-nine species were identified, 3 of which were additions to the previous assessment. We found strong separation of fish communities based on both habitat and depth, and an association between hard-bottom habitats and high biodiversity of reef fishes. With the declaration of Islas Marías as a natural reserve and relocation of the prison in 2019, there is an opportunity for the reserve to become a priority area for marine conservation on the Pacific coast of Mexico. Spatial analyses of fish biodiversity at Isla María Cleofas can help develop sustainable management strategies at a time when the governmental jurisdiction of the iconic archipelago is uncertain.

The life cycle of most benthic marine species includes a planktonic larval stage. Movement, largely by ocean currents, and survival during this stage drive patterns of variability and long-term persistence in adult populations, as well as connectivity among spatially separated populations. Here, we describe recent advances- many by PISCO-in understanding this stage and the resulting insights into population dynamics. Empirically, the past decade has seen advances in the use of both genetics (primarily parentage analysis) and ocean circulation simulations to resolve larval connectivity at ever-finer spatial and temporal scales. Additionally, deployment of standardized larval collectors at coast-wide scales has revealed striking patterns of spatial and interannual variability. In some cases, variability in larval settlement can be explained by oceanographic processes. However, there is a growing realization that predicting how many new juveniles will enter the adult population at a given location requires understanding not only larval transport pathways but also the spatial pattern and timing of larval production, and how the larval journey might affect post-larval survival and growth. Hence, a full understanding of larval connectivity requires information from benthic populations as well. This is particularly true in the context of climate change, as patterns of productivity and survival shift.

Shipwrecks can have significant localized effects when grounded on shallow coral reefs. These effects are not limited to the immediate physical damage, but can have wide-spread and lasting impacts due to alteration of the chemical makeup of the surrounding water column. This can subsequently impact the growth of benthic organisms, often leading to phase shifts and high levels of mortality of corals in the vicinity of the wreck. At Palmyra atoll, the grounding of a longline fishing vessel on the shallow reef terrace is associated with a phase shift to the corallimorph, Rhodactis howesii. In 2013, a wreck removal effort initiated by the US Department of Fish and Wildlife resulted in the successful extraction and disposal of the wreckage, after which the density and percent cover of R. howesii in the immediate vicinity of the wreck site dropped precipitously. Here, we document the response of the fish community to the wreck removal and localized decline in R. howesii. We show that the biomass of scarid parrotfishes and acanthurid surgeonfishes and unicornfishes (primarily herbivores) increased after the removal of the wreck, while biomass of chaetodontid butterflyfishes (primarily invertivores, many species are known to feed on coelenterate polyps) declined over the study period. The density of small scarids and acanthurids also increased, but only after a few years post removal. Overall these results indicate that Palmyra’s unfished herbivore population has rapidly responded to the removal of the wreck and associated decrease in corallimorph cover, can maintain high levels of grazing where space is made available for colonization of early successional algae species, and may have the potential to facilitate reef recovery.

In terrestrial systems it is well known that the spatial patterns of grazing by herbivores can influence the structure of primary producer communities. On coral reefs, the consequences of varied space use by herbivores on benthic community structure are not well understood, nor are the relative influences of bottom-up (resource abundance and quality), horizontal (competition), and top-down (predation risk) factors in affecting spatial foraging behaviors of mobile herbivorous fishes. In the current study we quantified space use and feeding rates of the parrotfish, Chlorurus spilurus , across a strong gradient of food resources and predator and competitor abundance across two islands with drastically different fisheries management schemes. We found evidence that while feeding rates of this species are affected by direct interference competition and chronic predation risk, space use appears to be primarily related to exploitative competition with the surrounding herbivore community. We found no evidence that predation risk influences diurnal foraging space use in this small bodied parrotfish species. Additionally, we found the influence of chronic predation risk on feeding rates of this species to be less dramatic than the results of recent studies that used model predators to measure acute behavioral responses of other species of herbivorous fishes. Our results indicate that the non-consumptive effects of predators on the foraging behaviors of coral reef herbivores may be less dramatic than previously thought.

Herbivory by fishes and sea urchins is a powerful mechanism on coral reefs that mitigates coral-algal competition by physically removing algae and creating bare space. Spatially constrained grazing by herbivores, particularly parrotfishes, may foster coral recruitment by creating a spatially continuous refuge of bare substrate for settlement and survival. However, frequent bouts of concentrated feeding potentially remove newly settled corals. Understanding the frequency and intensity of parrotfish foraging behavior at appropriate scales (months and meters) is essential for connecting herbivory with benthic processes. We documented the foraging behavior of a large, mobile coral reef herbivore (the steephead parrotfish Chlorurus microrhinos) on Palmyra Atoll using various techniques (observational follows, fish surveys, and bite scar tracking) across 2 habitat states (one dominated by algal turfs, one dominated by live coral and crustose coralline algae) that are representative of reefs throughout the Central Pacific. Large differences in the abundance of a preferred resource were associated with major differences in feeding behavior. Where resources were abundant and regrew quickly, foraging areas were small and spatially focused, resulting in dense patches of bite scars (> 100 bites m(-2)). Feeding behavior also showed a temporal periodicity, with individuals defending and regrazing the same area after regrowth occurred. In areas where resources were less abundant and recovered more slowly, parrotfish movements and foraging areas were significantly larger and bites were distributed sparsely across food patches. The large variability we observed within a single atoll suggests that characterizing species-specific foraging patterns from small-scale studies may not be appropriate.

Herbivorous fishes are being increasingly valued for their ecological function in coral reef systems, and consequently they have become the focus of management actions on many reefs around the world. Because many conservation actions require an understanding of the space use patterns of species of interest, there has been an increased effort in recent years to study the movement patterns and home range sizes of many herbivorous taxa. Also of great interest are the fine-scale foraging patterns of parrotfishes and the spatial and temporal scale of their interactions with benthic organisms. In this study, we performed a comprehensive evaluation of the movement patterns of the parrotfish Chlorurus microrhinos at multiple spatial and temporal scales at Palmyra Atoll in 2013-2015. We found that these fish have large home ranges when accounting for migrations to spawning and night refuge sites, but that within feeding territories, their activity is highly non-random and is quite spatially constrained and temporally episodic, indicating a high level of feeding selectivity. These patterns of foraging activity result in the patchy removal of algae from the reef, which may have consequences for the space competition between algae and corals.