Bioengineers and their associated fauna respond differently to the effects of biogeography and upwelling

Temperature and primary production (often linked to nutrient supply) are two of the few factors influencing species diversity and abundances across mesoscale gradients, while at smaller scales the habitat complexity offered by bioengineers is important. Previous studies have illustrated effects of upwelling and biogeography on intertidal bioengineers, but it is not known if these processes influence assemblages associated with those bioengineers in a similar way. We examined the habitat structure offered by two species of mussels and their associated fauna in five regions across 3000 km and three biogeographic provinces of the South African coast, replicating upwelling and non-upwelling areas within each region. Upwelling and region influenced the structure of mussel beds (the density and size of mussels). In contrast, upwelling did not influence mesoscale differences in composition, abundance, and numbers of species of crustaceans, mollusks, or polychaetes in mussel beds. Regardless of trophic level or mode of reproduction, mussel bed fauna were influenced only by region. Regional differences were strongly influenced by biogeography. The associated fauna was, however, also strongly correlated with the structure of the habitats created by mussels. Our results support the importance of upwelling to a critical ecosystem engineer, but show that these effects do not extend directly to the assemblages of associated fauna, which are more influenced by regional-scale effects and biogeography. We suggest that mesoscale patterns in the associated fauna of this bioengineered habitat are driven by the direct effects of biogeography, combined with the influence of biogeography and upwelling on mussel bed structure.     

Long-Term Effectiveness of Restoration Treatments on Closed Wilderness Campsites

This study assessed long-term recovery of vegetation on six wilderness campsites in subalpine forests in Oregon that were closed to use and that received common restoration treatments (scarification, soil amendments, mulch, transplanting, and seeding). Vegetation cover was assessed every year for the first 7 years following treatment, as well as 10 and 15 years after treatment. This made it possible to compare long-term treatment effectiveness to short-term efficacy. Plots that were closed and not scarified had virtually no vegetation cover even after 15 years without use. If long-used campsites in these subalpine forests are simply closed and allowed to recover on their own, restoration of undisturbed conditions will require hundreds if not thousands of years. Study results show, however, that simple treatments can accelerate recovery rates substantially. Scarification and transplanting were highly effective treatments, with seeding and soil amendment with organic matter and compost also contributing to success, but to a lesser degree. The use of a mulch mat, in contrast, had no effect, either positive or negative. Assessments of success conducted within the first few years of treatment overestimate treatment efficacy, particularly the effectiveness of soil amendments and seeding.     

Transient ontogenetic expression of hermaphroditic gonad morphology within the Gobiosoma group of the Neotropical seven-spined gobies (Teleostei: Gobiidae)

The Neotropical seven-spined gobies (tribe Gobiosomatini), including the Gobiosoma and Microgobius groups, constitute a speciose, monophyletic gobiid taxon. In particular, member species of the Gobiosoma group exhibit a combination of behavioral diversification and microhabitat specialization that may have played a major role in their collective rapid evolution and high rate of speciation. Functional hermaphroditism, which is common among gobiids, can promote exploitation of patchily distributed micro-niches by countering potential reductions in reproductive opportunities. However, the possible role of functional hermaphroditism in the exploitation of microhabitats and rapid speciation in the Gobiosoma group is unknown. One member species, Tigrigobius multifasciatus, is a functional hermaphrodite. Two other Gobiosoma group species are functionally gonochoric (i.e., constant-sexed), but exhibit transient hermaphroditic ovarian structure among immatures. In this study, ovarian morphology among immature and adult females of several Gobiosoma group species was examined to see if hermaphroditic gonadal features are present. Although no evidence of functional hermaphroditism in the form of precursive accessory gonadal structures (pAGS) associated with the adult ovary was found among newly examined species, all species exhibited the transient expression of hermaphroditic gonadal features associated with the immature ovary. In contrast, among six species of non-Gobiosomatini genera having no record of hermaphroditism, none exhibited similar transient hermaphroditic features associated with the immature ovary. These findings suggest that hermaphroditism may have been an ancestral trait which has been secondarily lost within some Gobiosoma group species. This study also shows that ontogenetic and morphogenic processes within the gobiid reproductive system may provide new insights into the evolution of life history traits and significantly further our understanding of the extraordinary evolutionary success of this group.     

Social spacing in the temperate marine goby Coryphopterus nicholsi

Coryphopterus nicholsi is a temperate marine goby that occupies rock rubble in protected subtidal areas along the Pacific coast of NOrth America. In field populations, fish of all sizes and both sexes are found in the same habitat. All observed fish over 25 mm standard length defended space during both the reproductive and the non-reproductive seasons, with territory size being directly correlated with fish size. There was peripheral overlap of territories, particularly between adjacent adult conspecifics of different size classes, but also with smaller fish that had territories centered in the interstices of larger territories. However, zones of overlap were used at different times by space-sharing fish so that defended areas remained temporally discrete. Access to areas of overlap appeared to be determined by dominance rank. More dominant (usually larger) fish used areas of overlap at will; the defense and use of shared areas by less dominant fish was contingent upon the absence of larger fish. Social organization in C. nicholsi appears to be defined by a combination of territorial behavior and dominance relationships among adjacent individuals, permitting the coexistence of all members of the population under circumstances of limited habitat availability.     

Conservation Implications of Introduced Game Birds in High-Elevation Hawaiian Shrubland

The Ring-necked Pheasant ( Phasianus colchicus ) and the Chukar ( Alectoris chukar ) are the dominant avifauna in high-elevation shrubland (2070–3000 m) of Haleakala National Park, Maui, Hawaii. We studied the food habits, ecological niche, and effects of these alien game birds on the native biota in this Hawaiian ecosystem. Analyses of crop contents indicated that pheasant and Chukar consumed predominantly fruits of native, woody dicots (39% and 47% respectively) and leaves (29% and 24% respectively) and flower parts (12% and 17% respectively) of alien, herbaceous dicots. Both species generally selected food items according to their relative availability, although other factors influenced choice of certain items. Invertebrates were a minor component of the game-bird diet, suggesting that their impact on native invertebrate populations is minimal. Pheasant and Chukar occupy, at least partially, an ecological niche once held by now-extinct or rare birds, and they appear not to be significant competitors with the endangered Nene. The role of these alien birds in facilitating seed dispersal and germination of native plant species is beneficial in restoring degraded ecosystems.     

Analysis of prospective epidemiologic studies on the neurobehavioural effects of lead

High-level lead exposure can have serious effects on the intellectual and behavioural development of young children. There has been much controversy in the last decade concerning the possible impact of low-level lead exposure upon the neurobehavioural and psychomotor development of children. Five longitudinal studies (Boston, Cincinnati, Cleveland, Port Pirie and Sydney) examining lead effects on child development were initiated in the early 1980s. These studies share multiple design features and include data on blood lead and neurobehavioural measurements from birth, six months, or annual intervals to seven years. All the studies use multivariate analysis to take into account possible confounding covariates with outcome measures.The studies tend to have varying results based on the covariates used and type of subject population. An analysis of the results of the five studies with regard to effects associated with prenatal and postnatal lead exposure and pregnancy outcome has been carried out and reveals inconsistencies in the onset, stability, and nature of neurobehavioural effects correlated with different indices of lead exposure. it is possible that the variation in reported results may be due to the use of different covariates and analyses among studies. A common analysis should be carried out among ail studies to further determine consistency of results. Although individual studies may show some effects, taken as a whole, the current published data from the five studies in this review are inconsistent and do not lend support to the concept that low level lead exposure resulting in blood lead levels below 25 g dL^–1 is associated with neurobehavioural deficits in children.     

Soil and water characteristics of a young surface mine wetland

Coal companies are reluctant to include wetland development in reclamation plans partly due to a lack of information on the resulting characteristics of such sites. It is easier for coal companies to recreate terrestrial habitats than to attempt experimental methods and possibly face significant regulatory disapproval. Therefore, we studied a young (10 years) wetland on a reclaimed surface coal mine in southern Illinois so as to ascertain soil and water characteristics such that the site might serve as a model for wetland development on surface mines. Water pH was not measured because of equipment problems, but evidence (plant life, fish, herpetofauna) suggests suitable pH levels. Other water parameters (conductivity, salinity, alkalinity, chloride, copper, total hardness, iron, manganese, nitrate, nitrite, phosphate, and sulfate) were measured, and only copper was seen in potentially high concentrations (but with no obvious toxic effects). Soil variables measured included pH, nitrate, nitrite, ammonia, potassium, calcium, magnesium, manganese, aluminum, iron, sulfate, chloride, and percent organic matter. Soils were slightly alkaline and most parameters fell within levels reported for other studies on both natural and manmade wetlands. Aluminum was high, but this might be indicative more of large amounts complexed with soils and therefore unavailable, than amounts actually accessible to plants. Organic matter was moderate, somewhat surprising given the age of the system.     

Imperfectly optimal animals

Summary We consider models of behavior that apply to two different problems: when a predator should leave a foraging site and how a female should choose the best available male. In each case we derive rules for an optimal solution to the problem. We also derive models based on very simple, plausible rules of behavior that we suspect animals may actually use. Although the expected payoffs from optimality models always exceed the expected payoffs from our simpler behavioral models, under certain conditions the difference is not large. When good foraging sites last but a short time and when females' mobility in their habitat is limited, the results of simple models and optimal models are very close indeed.Because of the difficulty of distinguishing between the results of each type of model and because natural selection will presumably provide a best mix of solutions to a range of problems rather than a best solution to any one problem, we suggest that behavioral ecologists expend more effort on simple, plausible models of animal behavior. Such models provide ready-made testable hypotheses about the animal's approximation to optimality and about the actual mechanisms of behavior.     

Changes in interacting species with disturbance

Human-influenced changes in the diversity and abundance of native wildlife in a southern boreal forest area, which became a national park in 1975, are used to develop working hypotheses for predicting and subsequently measuring the effects of disturbance or restoration programs on groups of interacting species. Changes from presettlement conditions began with early 1900 hunting, which eliminated woodland caribou (Rangifer tarandus) and elk (Cervus elaphus), and reduced moose (Alces alces) to the low numbers which still persist. Increases in white-tailed deer (Odocoileus virginianus), as these other cervid species became less abundant or absent, provided enough alternative food to sustain the system's carnivores until plant succession on previously burned or logged areas also caused deer to decline. With increased competition for reduced food, carnivore species also became less abundant or absent and overexploited some prey populations. The abilities of interacting species to maintain dynamically stable populations or persist varied with their different capacities to compensate for increased exploitation or competition. These relationships suggested a possible solution to the problem of predicting the stability of populations in disturbed systems. For the 1976–1985 period, a hypothesis that the increased protection of wildlife from exploitation in a national park would restore a more diverse, abundant, and productive fauna had to be rejected.