Invasive species are a growing global economic and ecological problem. Invasive Indo-Pacific lionfish (Pterois spp.) are known to have extreme negative effects on coral-reef communities in the Bahamas, so understating their distribution within and among reefs, what limits their local movements, and the effects they have on native prey species...
Although only a minority of introduced species become established and have noticeable consequences in their new communities, some can displace native species, alter food webs, and cause local extinctions. Studying these invasive species can provide new insights into basic ecological questions as well as inform management strategies. Pacific lionfish (Pterois...
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MarkA. Hixon
Although only a minority of introduced species become established and
Biological invasions have been identified as one of the prominent drivers of global environmental change. In particular, invasive predators typically have substantial negative effects on populations of native prey, even driving species to extinction in extreme cases. However, beyond direct predatory effects, little is understood regarding the specific mechanisms by...
What makes invasive species successful, and how do they affect native populations and communities? I addressed these key questions in the context of the invasion of Atlantic coral reefs by Pacific red lionfish (Pterois volitans). To assess the role of parasites in contributing to the success of this invasion, I...
Patterns of settlement of larvae and population dynamics
of juveniles are poorly known for coral reef fishes. During
1987 to 1989, I studied these phenomena in the domino
damselfish (Dascyllus albisella), a species endemic to the
Hawaiian Islands. Larvae settle onto branching coral heads
as new recruits (10-15 mm in...
Early theoretical models for the evolution of male-female
pairing were based largely on studies of birds. These models
assumed that biparental care of eggs and young was an
essential component of pairing. However, male-female pairing
is also a relatively common social system in coral-reef
fishes, and biparental care of young...
Ecologists have long questioned why fluctuating populations tend to persist rather than go extinct. Populations that persist indefinitely are regulated by mechanisms that cause demographic density dependence, which works to bound fluctuation above zero. In a series of studies, I have sought to determine the processes and mechanisms that regulate...
I examined two aspects of the reproductive behavior of the garibaldi, Hypsypops rubicundus, a temperate marine damselfish with male parental care. My primary objective was to determine the relationship between female choice and male parental investment in the care of offspring. In particular, I sought to determine: (1) how the...
The threespot damselfish, Stegastes planifrons,
maintains individual territories that are clustered on
coral patch reefs. My objective was to understand the
effects of territory clustering on behavior and fitness.
Fish with territories in the center of a cluster had
(relative to edge fish): higher mating success (number of
eggs), higher...
Understanding the dynamics of open marine populations is difficult. Ecological processes may vary with the spatial structure of the habitat, and this variation may subsequently affect demographic rates. In a series of observational and experimental studies in the Bahamas, I examined the roles of emigration, mortality, and predation in the...
Predatory lionfishes (Pterois volitans and P. miles) were introduced to Florida waters during the mid to late 1980s, and eventually established self-sustaining breeding populations in the tropical western Atlantic. These invasive species are now widespread along the southeastern seaboard of the United States, across the Caribbean Sea, and in the...
Understanding the processes that influence the composition of animal communities is a central goal in ecology. Interactions between established residents and colonizing juveniles that affect the subsequent survival of juveniles may influence community composition. In a series of experiments on coral reef fish communities in the Bahamas and Australia, I...
Many marine fish populations are severely declining due to over-fishing, loss of both juvenile and adult habitats, and accelerating environmental degradation. Fisheries management and the implementation of marine protected areas (MPAs) and other conservation tools are currently hindered by large gaps in knowledge about larval dispersal and its subsequent effects...
Many species have complex life cycles in which a dispersive larval stage is
followed by a relatively sedentary adult stage. For such species, reproductive output
is often high and large variation in survivorship throughout early life-history phases
(eggs and larvae) can lead to dramatic fluctuations in recruitment which may in...
Studies of geographic variation are central to understanding ecological and evolutionary processes. Geographic variation in the shell of the black abalone (Halioth cracherodii), a marine intertidal gastropod, involves both
clinal and local variation along the eastern Pacific coast in the number and size of tremata (=respiratory pores) on the shell....
Predators are fundamentally important for regulating and driving prey population dynamics as well as structuring ecological communities. Over-exploitation of marine resources has caused dramatic depletions of predatory fish species and shifts in marine community composition, with attendant declines in productivity and diversity of marine ecosystems. Despite the important ramifications of...
There is increasing awareness that human activities are altering the ways that natural systems operate and that local shifts in species composition and abundance can lead to abrupt and irreversible global change. Therefore, understanding the processes that buffer biological communities from critical shifts and how our actions affect natural stabilizing...
The lionfish (Pterois volitans) is a successful invasive predator with large impacts on native fish populations in the western Atlantic. Lionfish predation may affect competition between prey species so it is important to understand whether lionfish display preferences between prey species. I investigated lionfish and native graysby grouper prey preference...
he Great Barrier Reef Marine Park is widely known as one of the best-managed marine protected areas in the world. The park is divided into different management zones, the most prevalent of which are marine national park zones, which are designated as no-take, and conservation zones in which some regulated...
Because many coral-reef fishes are observable in situ, are amenable to transplantation, have small home ranges and short generation times, they provide a excellent system to investigate many topics within general ecology, fisheries biology, and conservation biology. The primary goal of this dissertation was to use the coral-reef fishes system...