Reef corals are likely to have many subtle but four gross responses to anomalous warm water. These are (1) not bleach and live (mortality <10%), (2) not bleach and die (mortality >20%), (3) bleach ...and live, and (4) bleach and die. The frequency of these four possible gross responses was determined for 18 common coral taxa over an exceptionally warm 1998 El Nino where intense bleaching was observed, and mortality determined from line transects averaged 41.2+/-34.7 (+/-SD). Field studies included (1) recording the loss of color (bleaching) and observing recently dead individuals among 6,803 colonies during five sampling periods and (2) estimating mortality based on 180 m of line-intercept transects completed 4 months before and near the end of the bleaching episode. There was no clear relationship between the loss of color and either direct observation or transect-based estimates of mortality for the 18 taxa. The morphology of the taxa did not influence color loss but branching and encrusting taxa had higher mortality than massive and submassive taxa. Loss of color and mortality are the most common responses to warm water as only Pavona did not lose color or die and only two taxa, Cyphastrea and Millepora, did not significantly lose color but died. Of the 15 taxa that lost color, five taxa, Astreopora, Favia, Favites, Goniopora, and Leptoria, did not die. These taxa are those most likely to have reduced potential mortality by the loss of pigments and associated algal symbionts. Death of the branching taxa was detected reasonably by direct field observation but some taxa were underestimated when compared with mortality estimates based on line transects. Death of encrusting and massive taxa including Echinopora, Galaxea, Hydnophora, Montipora, Platygyra, and massive Porites was poorly detected from direct observations but they proved to have modest to high mortality (20-80%) based on line transects. There was no single response of these common corals to warm water but these data, collected during an extreme warm-water anomaly, indicate that the loss of color is most frequently a sign of morbidity, particularly for branching and encrusting taxa. PUBLICATION ABSTRACT
Decadal-scale observations of marine reserves suggest that indirect effects on taxa that occur through cascading trophic interactions take longer to develop than direct effects on target species. ...Combining and analyzing a unique set of long-term time series of ecologic data in and out of fisheries closures from disparate regions, we found that the time to initial detection of direct effects on target species (±SE) was 5.13 ± 1.9 years, whereas initial detection of indirect effects on other taxa, which were often trait mediated, took significantly longer (13.1 ± 2.0 years). Most target species showed initial direct effects, but their trajectories over time were highly variable. Many target species continued to increase, some leveled off, and others decreased. Decreases were due to natural fluctuations, fishing impacts from outside reserves, or indirect effects from target species at higher trophic levels. The average duration of stable periods for direct effects was 6.2 ± 1.2 years, even in studies of more than 15 years. For indirect effects, stable periods averaged 9.1 ± 1.6 years, although this was not significantly different from direct effects. Populations of directly targeted species were more stable in reserves than in fished areas, suggesting increased ecologic resilience. This is an important benefit of marine reserves with respect to their function as a tool for conservation and restoration.
The role of a marine reserve and fisheries regulations in restoring fish populations on reefs disturbed by climate impacts was evaluated. Eight patch reefs, divided equally between no-fishing and ...fished zones in the remote Glover’s Reef atoll lagoon, were studied for 22 yr: 13 yr before and 9 yr after a ban on parrotfish capture. Findings indicate that the main effect of the fisheries closure was the recovery of targeted carnivorous species, notably snappers, jacks, and groupers. Recovery continued for most of the time series, including the later period when parrotfish capture was banned. Parrotfish abundance slowly declined in both management zones and across the ban period. The loss occurred for both small non-fished species, such as the striped parrot fish Scarus iserti, and for larger fished species, such as the stoplight Sparisoma viride and red-band parrotfish Sparisoma aurofrenatum. Consequently, parrotfish abundance appeared to be controlled by the ecology of these patch reefs rather than fishing mortality. We suggest that the high and persistent cover of late-successional algae reduces the renewal rates of algae, which had negative consequences for all studied parrotfish populations. Low ocean currents and physical energy in the lagoon appeared to promote algal persistence. Thus, parrotfish bans may be more effective in promoting reef recovery in environments that promote rapid algal turnover. Fisheries regulations are unlikely to rapidly restore hard corals on these patch reefs, which have slowly transitioned to algal dominance since first described in 1970.
We used linear and multivariate models to examine the associations between geography, biodiversity, per capita economic output, national spending on conservation, governance, and cultural traits in ...55 countries. Cultural traits and social metrics of modernization correlated positively with national spending on conservation. The global distribution of this spending culture was poorly aligned with the distribution of biodiversity. Specifically, biodiversity was greater in the tropics where cultures tended to spend relatively less on conservation and tended to have higher collectivism, formalized and hierarchical leadership, and weaker governance. Consequently, nations lacking social traits frequently associated with modernization, environmentalism, and conservation spending have the largest component of Earth's biodiversity. This has significant implications for setting policies and priorities for resource management given that biological diversity is rapidly disappearing and cultural traits change slowly. Therefore, we suggest natural resource management adapt to and use characteristics of existing social organization rather than wait for or promote social values associated with conservation spending. Supporting biocultural traditions, engaging leaders to increase conservation commitments, cross-national efforts that complement attributes of cultures, and avoiding interference with nature may work best to conserve nature in collective and hierarchical societies. Spending in modernized nations may be a symbolic response to a symptom of economic development and environmental degradation, and here conservation actions need to ensure that biodiversity is not being lost. Utilizamos modelos lineales y multivariados para examinar las relaciones entre la geografía, la biodiversidad, la producción per cápita y económica, el gasto nacional en conservación, la governanza y las características culturales en 55 países. Las características culturales y las medidas sociales de la modernización tuvieron una correlación positiva con el gasto nacional en conservación. La distribución global de esta cultura de gasto tuvo una alineación mínima con la distribución de la biodiversidad. En específico, la biodiversidad fue mayor en los trópicos en donde las culturas tuvieron la tendencia a gastar relativamente menos en la conservación y tuvieron la tendencia a tener un colectivismo mayor, liderazgo formalizado y jerárquico y gobiernos más débiles. En consecuencia, los países carentes de características sociales asociadas frecuentemente con la modernización, el ambientalismo y el gasto de conservación tienen el mayor componente de biodiversidad de la Tierra. Esto tiene implicaciones significativas para establecer políticas y prioridades para el manejo dado que la diversidad biológica está desapareciendo rápidamente y las características culturales cambian lentamente. Por esto, sugerimos que el manejo de recursos naturales se adapte y use las características de las organizaciones sociales existentes en lugar de esperar o promover valores sociales asociados con el gasto de conservación. Apoyar las tradiciones bioculturales, involucrar a los líderes para incrementar los compromisos de conservación, realizar esfuerzos internacionales que complementen los atributos de las culturas y evitar la interferencia con la naturaleza puede funcionar mejor para conservar la naturaleza en sociedades colectivas y jerárquicas. El gasto en los países modernizados puede ser una respuesta simbólica al síntoma del desarrollo económico y la degradación ambiental, y es aquí donde la conservación tiene que asegurar que no se está perdiendo la biodiversidad.
The hypothesis that herbivory is higher in areas without fishing and will increase the rate at which hard coral communities return to pre-disturbance conditions was tested in and out of the marine ...protected areas (MPA) of Kenya after the 1998 El Niño Southern Oscillation (ENSO). Herbivory was estimated by assay and biomass methods, and both methods indicated higher herbivory in fishery closures. Despite higher herbivory, the effect of the ENSO disturbance was larger within these closures, with reefs undergoing a temporary transition from dominance by hard and soft coral to a temporary dominance of turf and erect algae that ended in the dominance of calcifying algae, massive Porites, Pocillopora and a few faviids six years after the disturbance. The fished reefs changed the least but had a greater cover of turf and erect algae and sponge shortly after the disturbance. Higher herbivory in the fishery closures reduced the abundance and persistence of herbivore-susceptible erect algae and created space and appropriate substratum for recruiting corals. Nonetheless, other post-settlement processes may have had strong influences such that annual rates of coral recovery were low (~2%) and not different between the management regimes. Recovery, as defined as and measured by the return to pre-disturbance coral cover and the dominant taxa, was slower in fishery closures than unmanaged reefs.
► Vulnerability has three dimensions: exposure, sensitivity, and adaptive capacity. ► We explore vulnerability of coastal communities to the impacts of coral bleaching on fisheries. ► We develop a ...network-based approach to measure sensitivity to changes in the fishery. ► The three dimensions of vulnerability differ considerably. ► Key policy actions to reduce vulnerability at varying spatial and temporal scales.
Coral reefs support the livelihood of millions of people especially those engaged in marine fisheries activities. Coral reefs are highly vulnerable to climate change induced stresses that have led to substantial coral mortality over large spatial scales. Such climate change impacts have the potential to lead to declines in marine fish production and compromise the livelihoods of fisheries dependent communities. Yet few studies have examined social vulnerability in the context of changes specific to coral reef ecosystems. In this paper, we examine three dimensions of vulnerability (exposure, sensitivity, and adaptive capacity) of 29 coastal communities across five western Indian Ocean countries to the impacts of coral bleaching on fishery returns. A key contribution is the development of a novel, network-based approach to examining sensitivity to changes in the fishery that incorporates linkages between fishery and non-fishery occupations. We find that key sources of vulnerability differ considerably within and between the five countries. Our approach allows the visualization of how these dimensions of vulnerability differ from site to site, providing important insights into the types of nuanced policy interventions that may help to reduce vulnerability at a specific location. To complement this, we develop framework of policy actions thought to reduce different aspects of vulnerability at varying spatial and temporal scales. Although our results are specific to reef fisheries impacts from coral bleaching, this approach provides a framework for other types of threats and different social-ecological systems more broadly.
The failure of fisheries management among multispecies coral reef fisheries is well documented and has dire implications for the 100 million people engaged in these small‐scale operations. Weak or ...missing management institutions, a lack of research capacity, and the complex nature of these ecosystems have heralded a call for ecosystem‐based management approaches. However, ecosystem‐based management of coral reef fisheries has proved challenging due to the multispecies nature of catches and the diversity of fish functional roles. We used data on fish communities collected from 233 individual sites in 9 western Indian Ocean countries to evaluate changes in the site's functional composition and associated life‐history characteristics along a large range of fish biomass. As biomass increased along this range, fish were larger and grew and matured more slowly while the abundance of scraping and predatory species increased. The greatest changes in functional composition occurred below relatively low standing stock biomass (<600 kg/ha); abundances of piscivores, apex predators, and scraping herbivores were low at very light levels of fishing. This suggests potential trade‐offs in ecosystem function and estimated yields for different management systems. Current fishing gear and area restrictions are not achieving conservation targets (proposed here as standing stock biomass of 1150 kg/ha) and result in losses of life history and ecological functions. Fish in reefs where destructive gears were restricted typically had very similar biomass and functions to young and low compliance closures. This indicates the potentially important role of fisheries restrictions in providing some gains in biomass and associated ecological functions when fully protected area enforcement potential is limited and likely to fail. Our results indicate that biomass alone can provide broad ecosystem‐based fisheries management targets that can be easily applied even where research capacity and information is limited. Of particular value, is our finding that current management tools may be used to reach key ecosystem‐based management targets, enabling ecosystem‐based management in many socioeconomic contexts.
Knowing the responses of high-latitude corals to thermal impacts will be critical to predicting the possibility for range expansion of reefs provoked by climate change. We, therefore, tested how ...oceanographic and island geography variation and subsequent interactions between chronic and acute environmental stresses would influence the temperate corals of Mauritius (~ 20°S). Specifically, we predicted higher impacts of thermal stress due to rare events on ocean-impacted windward than leeward reefs. To test this prediction, surveys of benthic cover and corals in the shallow lagoon’s perimeter reefs were repeated between 2004 and 2019—an interval with frequent warm thermal anomalies. Hard and soft coral cover declined 40% and 83%, respectively, and erect algae increased 78% over the 15-yr interval. Coral taxa were distributed along a
Montipora
-community axis dominant on the island’s leeward reefs and an
Acropora
-axis dominant on the windward reefs. Nine of the 30 originally encountered sub-genera were not observed in the second sampling, of which most losses were on the windward reefs and among taxa that were initially uncommon during the initial 2004 sampling. The largest declines occurred in the southeast where rare acute stress was higher and open-ocean conditions interacted strongly with the island. The north and western corals experienced less acute stress and greater persistence of taxa. Searching an additional 15 sites in 2019 found six of the missing coral taxa, often in deeper reef edges. Screening of potential environmental variables indicated that that skewness of the degree heating weeks and thermal stress anomalies were the strongest predictor of the changes. A chronic stress metric was more difficult to identify but water flow variability and chlorophyll-a concentrations were part of the oceanographic conditions associated with attenuated responses to acute stress. Frequent acute stress was associated with lower thermal acclimation rates over the 15-yr interval and more evident for the dominant than subdominant taxa. The extra-equatorial location of Mauritius will not ensure latitudinal sanctuary, apart from the leeward reefs.
Herbivory is a key process that controls the abundance and accumulation of algal turf on tropical coral reefs. The capacity of reefs to prevent algal accumulation hinges on the balance between algal ...production and consumption (i.e., grazing). In this study, we quantify algal turf biomass accumulation and grazing using experimental substrata and herbivore exclusion cages across sites in Kenya that represent different levels of fisheries management: heavily fished reefs, community marine-protected areas less than 10 yr old, and older government-managed marine-protected areas. These reefs had different assemblages of grazing herbivores with fished reefs being dominated by sea urchins, while government closures had a high abundance of grazing fishes, in particular parrotfishes. The community fisheries closures had an intermediate mix of sea urchins and grazing fishes, with the latter dominated by surgeonfishes. These management regimes mediated algal biomass on experimental substrata such that urchins consumed as much as 90% on fished reefs and fishes as much as 96% at the government marine-protected areas by the end of the 390-d trial. The younger community fisheries closures lacked the herbivory to significantly reduce algal biomass, and consumption was less than 50% of production and never greater than 2 g algae m
−2
d
−1
. These findings point to the importance of recovery dynamics of herbivorous fishes from heavy fishing pressure. They also suggest that while sea urchins might be effective grazers to prevent macroalgal dominance, they are not a functional replacement for fishes due to their ability to reduce reef accretion through bioerosion and prevent settlement of crustose coralline algae in this system.
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