Host-parasite Interactions between a Copepod () and Small Reef-associated Gobies () in the British Virgin Islands.

The effects of parasitic copepods on free-living hosts are infrequently documented, and the copepod has remained virtually unstudied since described. For the first time, we document its host range in the British Virgin Islands (BVI), the prevalence and intensity of infections on wild hosts, and its impacts on host morphology and performance. Infections were observed on four benthic gobies in the BVI (, , and ) but not on other host species previously reported from other parts of the western Atlantic.

Using DNA barcoding to identify host-parasite interactions between cryptic species of goby (Coryphopterus: Gobiidae, Perciformes) and parasitic copepods (Pharodes tortugensis: Chondracanthidae, Cyclopoida).

Previous work, using morphological characters, identified a generalist copepod parasite (Pharodes tortugensis) at high prevalence on two common gobies (Coryphopterus glaucofraenum and C. dicrus) in the British Virgin Islands (BVI). DNA barcoding subsequently revealed C.

Behavioural mechanisms underlying parasite-mediated competition for refuges in a coral reef fish.

Parasites have been increasingly recognized as participants in indirect ecological interactions, including those mediated by parasite-induced changes to host behaviour (trait-mediated indirect interactions or TMIIs). In most documented examples, host behaviours altered by parasites increase susceptibility to predation because the predator is also a host (host-manipulation). Here, we test for a TMII in which a parasitic copepod modifies the predator-prey interaction between a small goby host and several larger predatory fish.

Boat anchoring contributes substantially to coral reef degradation in the British Virgin Islands.

Community decline is often linked to anthropogenic activities. Coral reef declines, for example, have been linked to overfishing and climate change, but impacts of coastal development, pollution, and tourism have received increasing attention. Here, we isolated the impact of one little-studied aspect of recreational activity on coral reefs-damage from boat anchoring-by performing a survey of 24 sites in the British Virgin Islands (BVI) subject to varying levels of anchoring activity.

Evaluating how variants of floristic quality assessment indicate wetland condition.

Biological indicators are useful tools for the assessment of ecosystem condition. Multi-metric and multi-taxa indicators may respond to a broader range of disturbances than simpler indicators, but their complexity can make them difficult to interpret, which is critical to indicator utility for ecosystem management. Floristic Quality Assessment (FQA) is an example of a biological assessment approach that has been widely tested for indicating freshwater wetland condition, but less attention has been given to clarifying the factors controlling its response.

Comparing fishers' and scientific estimates of size at maturity and maximum body size as indicators for overfishing.

We tested whether fishers' local ecological knowledge (LEK) of two fish life-history parameters, size at maturity (SAM) at maximum body size (MS), was comparable to scientific estimates (SEK) of the same parameters, and whether LEK influenced fishers' perceptions of sustainability. Local ecological knowledge was documented for 82 fishers from a small-scale fishery in Samaná Bay, Dominican Republic, whereas SEK was compiled from the scientific literature. Size at maturity estimates derived from LEK and SEK overlapped for most of the 15 commonly harvested species (10 of 15).

Episodic Disturbance from Boat Anchoring Is a Major Contributor to, but Does Not Alter the Trajectory of, Long-Term Coral Reef Decline.

Isolating the relative effects of episodic disturbances and chronic stressors on long-term community change is challenging. We assessed the impact of an episodic disturbance associated with human visitation (boat anchoring) relative to other drivers of long-term change on coral reefs. A one-time anchoring event at Crab Cove, British Virgin Islands, in 2004 caused rapid losses of coral and reef structural complexity that were equal to the cumulative decline over 23 years observed at an adjacent site.

High population density enhances recruitment and survival of a harvested coral reef fish.

A negative relationship between population growth and population density (direct density dependence) is necessary for population regulation and is assumed in most models of harvested populations. Experimental tests for density dependence are lacking for large-bodied, harvested fish because of the difficulty of manipulating population density over large areas. We studied a harvested coral reef fish, Lutjanus apodus (schoolmaster snapper), using eight large, isolated natural reefs (0.

Marine reserves as linked social-ecological systems.

Marine reserves are increasingly recognized as having linked social and ecological dynamics. This study investigates how the ecological performance of 56 marine reserves throughout the Philippines, Caribbean, and Western Indian Ocean (WIO) is related to both reserve design features and the socioeconomic characteristics in associated coastal communities. Ecological performance was measured as fish biomass in the reserve relative to nearby areas.

Inter-cohort competition drives density dependence and selective mortality in a marine fish.

For organisms with complex life cycles, the transition between life stages and between habitats can act as a significant demographic and selective bottleneck. In particular, competition with older and larger conspecifics and heterospecifics may influence the number and characteristics of individuals successfully making the transition. We investigated whether the availability of enemy-free space mediated the interaction between adult goldspot gobies (Gnatholepis thompsoni), a common tropical reef fish, and juvenile conspecifics that had recently settled from the plankton.

Recent region-wide declines in Caribbean reef fish abundance.

Profound ecological changes are occurring on coral reefs throughout the tropics, with marked coral cover losses and concomitant algal increases, particularly in the Caribbean region. Historical declines in the abundance of large Caribbean reef fishes likely reflect centuries of overexploitation. However, effects of drastic recent degradation of reef habitats on reef fish assemblages have yet to be established.

Musical chairs mortality functions: density-dependent deaths caused by competition for unguarded refuges.

Structural refuges within which prey can escape from predators can be an important limiting resource for the prey. In a manner that resembles the childhood game of musical chairs, many prey species rapidly retreat to shared, unguarded refuges whenever a predator threatens, and only when refuges are relatively abundant do all prey individuals actually escape. The key feature of this process is that the per capita prey mortality rate depends on the ratio of prey individuals to refuges.

SPATIAL DENSITY DEPENDENCE SCALES UP BUT DOES NOT PRODUCE TEMPORAL DENSITY DEPENDENCE IN A REEF FISH.

Field experiments provide rigorous tests of ecological hypotheses but are typically of short duration and use small spatial replicates. We assessed empirically whether the results of experiments testing for density dependence applied at larger spatial domains and explained temporal population dynamics. We studied a small coral reef fish, the goldspot goby (Gnatholepis thompsoni), in the Bahamas.

Parasitism and a shortage of refuges jointly mediate the strength of density dependence in a reef fish.

Various predator-prey, host-pathogen, and competitive interactions can combine to cause density dependence in population growth. Despite this possibility, most empirical tests for density-dependent interactions have focused on single mechanisms. Here we tested the hypothesis that two mechanisms of density dependence, parasitism and a shortage of refuges, jointly influence the strength of density-dependent mortality.

Assessing the magnitude of intra- and interspecific competition in two coral reef fishes.

Many field experiments have tested for effects of competition in nature, but relatively few have used designs allowing simultaneous assessment of the influence of intra- and interspecific competition. Using a response surface design and a press manipulation of densities, we tested effects of competition within and between two species of coral reef fishes (Coryphopterus glaucofraneum and Gnatholepis thompsoni). By tracking individually tagged fishes, we showed that the per-capita effect of intraspecific competitors on individual growth was at least twice as great as the effect of interspecific competitors.

Small-scale field experiments accurately scale up to predict density dependence in reef fish populations at large scales.

Field experiments provide rigorous tests of ecological hypotheses but are usually limited to small spatial scales. It is thus unclear whether these findings extrapolate to larger scales relevant to conservation and management. We show that the results of experiments detecting density-dependent mortality of reef fish on small habitat patches scale up to have similar effects on much larger entire reefs that are the size of small marine reserves and approach the scale at which some reef fisheries operate.

Growth of estuarine fish is associated with the combined concentration of sediment contaminants and shows no adaptation or acclimation to past conditions.

We tested whether the growth rates of small benthic fish (Gillichthys mirabilis) in three southern California estuaries corresponded with the local concentrations of contaminants. Fish originating from each estuary were transplanted to cages in each estuary in two reciprocal transplant experiments. The growth rates of caged fish, and the size-distribution of natural populations, showed the same pattern of difference among estuaries.

Strong density-dependent survival and recruitment regulate the abundance of a coral reef fish.

Debate on the control of population dynamics in reef fishes has centred on whether patterns in abundance are determined by the supply of planktonic recruits, or by post-recruitment processes. Recruitment limitation implies little or no regulation of the reef-associated population, and is supported by several experimental studies that failed to detect density dependence. Previous manipulations of population density have, however, focused on juveniles, and there have been no tests for density-dependent interactions among adult reef fishes.

Effects of trout on the diel periodicity of drifting in baetid mayflies.

Some benthic invertebrates in streams make frequent, short journeys downstream in the water column (=drifting). In most streams there are larger numbers of invertebrates in the drift at night than during the day. We tested the hypothesis that nocturnal drifting is a response to avoid predation from fish that feed in the water column during the day.