Small alteration – big impacts: effects of small-scale riparian forest management on host–parasite dynamics in streams

Infection status of masu salmon Oncorhynchus masou by the parasite Salmonema cf. ephemeridarum (Nematoda, Cystidicolidae)

Nematodes that parasitize salmonids are found in both seawater and freshwater. Unlike seawater species such as those in family Anisakidae, freshwater species have not been well studied. In particular, the influences of these nematodes on the body condition of salmonids remain unclear. We studied the effects of Salmonema cf. ephemeridarum on the body condition of masu salmon Oncorhynchus masou. We found a positive relationship between the number of parasites and fish fork length. In contrast, we found a negative relationship between the body condition (condition factor) of fish and the number of parasites. These results suggest that nematode infection could affect host energy reserves for future growth.

The general architecture of black fly-parasite interactions: Parasitism in lotic systems at a continental scale

We examined the general architecture of interactions between stream-dwelling larval black flies (Diptera: Simuliidae) and their common parasites in 1736 collections across North America. Mermithid nematodes (family Mermithidae), microsporidia (phylum Microsporidia), and the fungus Coelomycidium simulii Debaisieux (phylum Blastocladiomycota) infected larval black flies. We found similar continental distributions for these three parasite taxa across North America. At least one of these taxa was represented in 42.2% of all black fly collections. Species interactions in ecological networks typically imply that each link between species is equally important. By employing quantitative measures of host susceptibilities and parasite dependencies, we provide a more complete structure for host-parasite networks. The distribution of parasite dependencies and host susceptibilities were right-skewed, with low values indicating that most dependencies (parasites) and susceptibilities (hosts) were weak. Although regression analysis between host frequency and parasite incidence were highly significant, frequency analysis suggested that the distributions of parasites differ significantly among the four most common and closely related (same subgenus) species of hosts. A highly significant pattern of nestedness in our bipartite host-parasite network indicated that specialized parasites (i.e., those that interact with few host species) tend to occur as subsets of the most common hosts.

Conservation and Management Strategies Create Opportunities for Integrative Organismal Research

Conservation and management activities are geared toward the achievement of particular goals for a specific species, or groups of species, at the population level or higher. Conversely, organismal or functional research is typically organized by hypothesis tests or descriptive work that examines a broader theory studying individual organismal traits. Here, we outline how integrative organismal biologists might conduct mutually beneficial and meaningful research to inform or assist conservation and management biologists. We argue that studies of non-target species are very useful to both groups because non-target species can meet the goals of managers and organismal biologists alike, while also informing the other. We highlight our work on a threatened lizard species' thermal physiology, behavior, and color pattern-all of which are impacted by species management plans for sympatric, threatened, bird species. We show that management practices affect activity time, thermal adaptation, and substrate use, while also altering predation rates, crypsis, ectoparasite load, and sexual coloration in the study species. These case studies exemplify the challenges of conservation and management efforts for threatened or endangered species in that non-target species can be both positively and negatively affected by those efforts. Yet, the collaboration of organismal biologists with conservation and management efforts provides a productive system for mutually informative research.