Fish ectoparasite detection, collection and curation

Fish parasitology is a dynamic and internationally important discipline with numerous biological, ecological and practical applications. We reviewed optimal fish and parasite sampling methods for key ectoparasite phyla (i.e. Ciliophora, Platyhelminthes, Annelida and Arthropoda) as well as recent advances in molecular detection of ectoparasites in aquatic environments. Ideally, fish capture and anaesthesia as well as parasite recovery methods should be validated to eliminate potential sampling bias and inaccuracy in determining ectoparasite population parameters. There are considerable advantages to working with fresh samples and live parasites, when combined with appropriate fixation methods, as sampling using dead or decaying materials can lead to rapid decomposition of soft-bodied parasites and subsequent challenges for identification. Sampling methods differ between target phyla, and sometimes genera, with optimum techniques largely associated with identification of parasite microhabitat and the method of attachment. International advances in fish parasitology can be achieved through the accession of whole specimens and/or molecular voucher specimens (i.e. hologenophores) in curated collections for further study. This approach is now critical for data quality because of the increased application of environmental DNA (eDNA) for the detection and surveillance of parasites in aquatic environments where the whole organism may be unavailable. Optimal fish parasite sampling methods are emphasised to aid repeatability and reliability of parasitological studies that require accurate biodiversity and impact assessments, as well as precise surveillance and diagnostics.

Checklist of parasitic isopods from Brazil: Bopyroidea and Cryptoniscoidea (Isopoda: Cymothoida: Epicaridea)

All species of Brazilian parasitic isopods belonging to Epicaridea (Bopyroidea and Cryptoniscoidea) known to date, including references and distribution information, are listed. The list comprises 37 valid species, 18 of which are endemic to the country, 17 are also recorded from other countries in the Americas, and only two species are distributed outside of the American continent as well. Synonym list, known hosts and distribution are given for each of the species, along with taxonomic and ecological remarks when relevant.

Effects of River Hydrology and Physicochemistry on Anchovy Abundance and Cymothoid Isopod Parasitism

The flow regime of a river is an important driver of many ecosystem components. However, few studies explore how differences in flow rates and water chemistry can influence communities of parasites and their hosts. Here, we investigate the impact of dissolved oxygen, pH, salinity, water temperature, and river flow on the abundance and prevalence of cymothoid isopod parasitism (Lironeca ovalis) of the Bay Anchovy (Anchoa mitchilli) in the Alafia and Hillsborough rivers of Tampa Bay (Florida). We also explore seasonality by comparing monthly samples preserved throughout 2005-2007. Although both the Alafia and Hillsborough rivers had similar average water temperatures and salinity, and similar wet and dry season cycles, the upstream damming of the Hillsborough River had numerous negative effects on water flow rate, dissolved oxygen content, and acidity. This disruption in water quality corresponded with a lower abundance of anchovy hosts, fewer free-swimming cymothoids, and low prevalence of anchovy parasitism. Anchovies were much more abundant in the Alafia River, but flow negatively affected abundance-a negative effect that could be mitigated by positive changes in water temperature, salinity, and pH. Flow rates also negatively affected free-swimming cymothoid abundance; however, water flow was less important in predicting their parasitism of anchovies. In Alafia, fewer anchovies were parasitized when dissolved oxygen was high and water acidity was low, but more were parasitized during the wet season. These findings corroborate predictions that flow can moderate habitat stability and complexity which, in turn, can impact opportunities for parasitism of host communities.

Life Cycle and Life History Strategies of Parasitic Crustacea

Different parasitic life strategies are described including four new life cycles: complex rebrooding, micro-male, mesoparasite and prey-predator transfer. Four new life cycle behaviours are named: nursery hiding, mid-moult stage, positive precursor (intraspecific antagonism) and negative precursor (ambush strategy). Further strategies discussed are opossum attack, double parasitism (doubling of the normal reproductive set), duplex arrangement (separated male-female pairs), simple rebrooding, and describing how displaced parasites and superinfections may partly elucidate life cycles. Proportional stunting masks life history effects of parasitism; cuckoo copepods are true parasites and not just associates; burrowing barnacles (acrothoracicans) are not parasites. Further findings based on life cycle information: branchiurans and pentastomes are possibly not related; firefly seed shrimp are not parasites; copepod pre-adult life cycle stages are common in the western pacific but rare in Caribbean; harpacticoids on vertebrates are not parasites; cuckoo copepods are true parasites; explained the importance of pennellid intermediate hosts. Crustacean parasite life cycles are largely unknown (1% of species). Most crustacean life cycles represent minor modifications from the ancestral free-living mode. Crustacean parasites have less complex and less modified life cycles than other major parasite groups. This limits their exploitation of, and effectiveness, in parasitism. However, these life cycles will be an advantage in Global Change. Most metazoan parasites will be eliminated while crustaceans (and nematodes) will inherit the new world of parasites.

History of Discovery of Parasitic Crustacea

Parasitic Crustacea have been present in scientific literature since Linnaeus introduced the first classification system (binomial nomenclature). Crustaceans are considered to be the most morphologically diverse arthropods, with currently 19 parasitic orders known to science. This chapter reviews the history of discovery for each of the major parasitic Crustacea groups, highlighting some of the key developments that have influenced our current understanding of these parasites. Each taxonomic group is briefly introduced, followed by a synopsis on some of the outstanding contributions within that group. Knowledge development is followed, from the first parasites discovered to other historical highlights that influenced the groups up to this point. Other important discoveries (both taxonomic and ecological) are also noted, serving as a preview to the host-parasite interactions covered in the subsequent chapters. Additionally, several researchers who have added significant contributions to our knowledge of the parasitic Crustacea (specifically in taxonomy and discovery) are introduced, along with photographs of a select few. This historical review of the crustacean parasites provides a background to these diverse and abundant organisms and will contribute to a better understanding of their unique niche in the aquatic environment.