Proportionality of Population Descriptors of Metacercariae of Clinostomum marginatum in the Orobranchial Cavity of Black Bass (Micropterus spp.) from Arkansas Ozark and Ouachita Streams

In a previous study of Clinostomum marginatum metacercariae in Micropterus dolomieu, I reported that the population parameters of mean abundance, standard deviation, maximum abundance, mean intensity and mean intensity standard deviation were proportional between the total population and the orobranchial numbers for 16 locations in Arkansas Ozark and Ouachita streams. This allowed an assessment of the parasite populations by only examining the mouth and gill areas without sacrificing a valued sports fish. The present study examined the same orobranchial parameters utilizing correlation and descriptive statistics to determine if proportionality also existed between the different localities. I have now included an analysis of skewness and kurtosis (drift and shape) of the populations’ curves. Proportionality of regression values was highly significant in terms of R² and P between all parameters except prevalence, which showed much weaker correlations with the other parameters. The interpretation of these results is that the distribution of infections in the different bass populations are density independent i.e., although the numbers of parasites change from location to location, the pattern of distribution in the host populations remains similar. This may best be explained by a spatiality of distance from the infection source (snails) and nonrandom distribution of hosts (bass) producing aggregation near the snails and a negative binomial distribution throughout the population

Proportionality Between Population Descriptors (Covariables) in an Aggregated Acanthocephalan (Helminth) Infection of a Microcrustacean: Crofton Revisited

We have previously shown that population parameters of the trematode metacercariae of Clinostomum marginatum in black bass (Micropterus spp.) were closely correlated with each other with the exception of prevalence (Daly et al. 2007, Daly (2014). Crofton (1971) and Haynes and Nicholas (1963) published raw data on an acanthocephalan, (Polymorphus minutus) in an amphipod intermediate host collected on 6 different sites on a stream. That data was used herein to examine similar correlations, as with Clinostomum, to see if another helminth infection, in this case from a different phylum, also had similar descriptor relationships. Forty one regression analyses were done on parameter data from the populations of P. minutus as described by Crofton and Haynes and Nichols. Descriptors used were mean abundance and standard deviation, maximum number, prevalence, mean intensity and standard deviation, dispersion coefficient, and skewness and kurtosis (shape parameters of the population curves). Results showed that the parameters most usually reported to describe helminth infections were, as with Clinostomum, strongly correlated with each other. One difference being prevalence, in which P. minutus prevalence was significantly correlated with other parameters. Dispersion coefficients (standard deviation/mean) were independent (not significant) of an effect by the other parameters. Skewness and kurtosis were very highly correlated within the two population types (mean and mean intensity) but not with other descriptors. Since population parameters are important in the description of parasitic infections, it would seem that more data on more helminths are needed to determine if this proportionality is a universal phenomenon of stochastic and random helminth infections or just coincidentally found in C. marginatum and P. minutus juvenile infections

Non-Invasive Technique for Assessing the Population Parameters of Metacercariae of Clinostomum marginatum in Smallmouth Bass (Micropterus dolomieu)

Clinostomllm marginatum is a trematode that uses a fish as its final intennediate host. The wonns in the fish are in metacercarial cysts and are known as yellow grub. Yellow grubs give the fish\u27s flesh a wonny, unappetizing appearance and are a problem for commercial fish fanners in that heavily infected fish are not suitable for marketing. The parasite is common in smallmouth bass (Micropterus dolomieu) living in upland streams of Arkansas where the bass may serve as a wild reservoir for contamination of commercial fish ponds. Because smallmouth bass are a prized game fish, it would be desirable to be able to assess the extent of yellow grub infections by a non-invasive method whereby the fish could be examined and returned to its habitat without destructive necropsy. In this study strong correlations were found between the parasites seen in the orobranchial region and the rest of the host body. These correlations were found for all of the population parameters usually reported. The significance of these findings are mainly three fold: (I) The correlations allowed a reasonable estimate of yellow grub loads in populations of smallmouth bass using only orobranchial counts, (2) in situ examination of the mouth and gills alone allows the fish to be returned unharmed to the stream and (3) similar anatomical-site density correlations applied to other parasitic infections might dramatically reduce the amount of necropsy time needed for estimating total parasite numbers. Examples for the latter are given from other studies with Clinostomum complanatum and Proteocephalus ambloplitis species that show similar anatomical site density relationships in their respective hosts

State of the California current 2013-14: El niño looming

In 2013, the California current was dominated by strong coastal upwelling and high productivity. Indices of total cumulative upwelling for particular coastal locations reached some of the highest values on record. Chlorophyll a levels were high throughout spring and summer. Catches of upwelling-related fish species were also high. After a moderate drop in upwelling during fall 2013, the California current system underwent a major change in phase. Three major basin-scale indicators, the PDO, the NPGO, and the ENSO-MEI, all changed phase at some point during the winter of 2013/14. The PDO changed to positive values, indicative of warmer waters in the North Pacific; the NPGO to negative values, indicative of lower productivity along the coast; and the MEI to positive values, indicative of an oncoming El Niño. Whereas the majority of the California Current system appears to have transitioned to an El Niño state by August 2014, based on decreases in upwelling and chlorophyll a concentration, and increases in SST, there still remained pockets of moderate upwelling, cold water, and high chlorophyll a biomass at various central coast locations, unlike patterns seen during the more major El Niños (e.g., the 97-98 event). Catches of rockfish, market squid, euphausiids, and juvenile sanddab remained high along the central coast, whereas catches of sardine and anchovy were low throughout the CCS. 2014 appears to be heading towards a moderate El Niño state, with some remaining patchy regions of upwellingdriven productivity along the coast. Superimposed on this pattern, three major regions have experienced possibly non-El Niño-related warming since winter: the Bering Sea, the Gulf of Alaska, and offshore of southern California. It is unclear how this warming may interact with the predicted El Niño, but the result will likely be reduced growth or reproduction for many key fisheries species