Parasite communities of the Salzhaff (Northwest Mecklenburg, Baltic Sea) II. Guild communities, with special regard to snails, benthic crustaceans, and small-sized fish

Abstract

Metazoan parasites of guilds of benthic snails and crustaceans and of four fish families--Gobiidae, Gasterosteidae, Syngnathidae, and Zoarcidae--were investigated off the brackish Salzhaff area (Southwest Baltic) in the semienclosed Salzhaff and the near Rerik Riff in the free Baltic. Comparisons revealed greater similarities in parasite populations and communities within the fish guilds than between them. According to an evaluation of the core-/satellite-species concept using abundance values, the most important parasites of fish were some generalists, such as Cryptocotyle spp., Podocotyle atomon, and Diplostomum spathaceum, as well as some specialists, such as Acanthostomum balthicum, Thersitina gasterostei, and Aphalloides timmi. These specialists revealed high degrees of prevalence in their main hosts and lower degrees in one or two by-hosts. Additional importance is assigned to parasites that cause harm to their hosts due to their large size, e.g., Schistocephalus spp., or via massive infestation, e.g., several digenean metacercariae. Because specialists were more prominent in snails and fish from the Rerik Riff, the correlation of host numbers with prevalence resulted in only a slight increase instead of a more rapid rise in regression among crustaceans and fish from the entire Salzhaff, where the generalists were more prevalent. The selected host guilds demonstrated the entire life cycles of three digeneans (P. atomon, A. balthicum, A. timmi), one acanthocephalan (Echinorhynchus gadi), and one nematode (Hysterothylacium sp.). The prevalence increased in these cycles from host level to host level and attained relatively high values in all guilds. The parasite fauna of the Salzhaff area is influenced by eutrophication stress, which leads to a high level of productivity and, consequently, to great densities in primary consumers such as snails and crustaceans. These are attractive for several secondary consumers such as fish and birds, which is the reason for the existence of at least 24 autogenic and 20 allogenic parasite species at this locality. The slight surplus of the first category indicates a yet-balanced environment in the investigation area.

The parasites of the invasive Chinese sleeperPerccottus glenii(Fam. Odontobutidae), with the first report ofNippotaenia mogurndaein Ukraine

“…The gradual scale for the intensity of infection was adopted: 1) sporadic occurrence, "S" -1 or a few specimens in the examined material; 2) not numerous, "NN" -a few specimens in a few fields of vision; 3) numerous, "N" -up to 20 individuals in most fields of vision; 4) very numerous, "VN" -more than 20 individuals in most fields of vision; 5) mass occurrence, "M" -hundreds of individuals in each field of vision. The relative importance of parasites was judged by the core-satellite concept according to their abundance (A): >2 = core species, 0.6-2 = secondary species; 0.2-0.6 = satellite species; and <0.2 = rare species (Zander et al, 2000). The Index of Czekanowski-Sørensen, ICS (Sørensen, 1948), was used to compare the parasite faunas: ICS = 2c a+b × 100%, where a is the number of parasite species found in locality A, b is the number of parasite species found in locality B, and c is the number of parasitic species common to both localities.…”

Communities of metazoan parasites of two fishes of the Proterorhinus genus (Actinopterygii: Gobiidae)

“…The similarity between the metazoan parasite fauna of P. marmoratus and P. semilunaris (ICS) was 12.5 %. The analysis of importance of parasites follows the scale of Zander et al (2000) which shows that there are five core species in the parasite component community of P. marmoratus: Cryptocotyle concavum (Creplin, 1825) was a core species in all localities of occurrence (except the Gulf of Odessa), C. lingua (Creplin, 1825) in all localities, Timoniella imbutiforme (Molin, 1859) was a core species only in the Hryhorivsky Estuary, and Acanthocephaloides propinquus (Dujardin, 1845) in all localities (except the Hryhorivsky Estuary) ( Table 2). The only secondary spe- (Table 2).…”

“…The prevalence (P, %), intensity (presented as intensity range, IR), mean intensity (MI), and abundance (A) were calculated according to Bush et al (1997). The importance of parasites is judged by an altered core-/satellite concept according to their abundance: >2 = core species, 0.6 -2 = secondary species; 0.2 -0.6 = satellite species; and <0.2 = rare species (Zander et al, 2000). The tendency to join the infracommunity was evaluated according to the Infracommunity Index, ICI (Zander, 2004):…”

Metazoan parasites from herring (Clupea harengus L.) as biological indicators in the Baltic Sea

“…Metacercaria of the digenean parasite Diplostomum spathaceum only occurred in the northernmost sampling sites (sampling site 5, 6), where the salinity was lowest (6.9 and 5.5PSU, resp.). The distribution limit is linked to the occurrence of their first intermediate host, the snail Radix ovata (Zander et al 2000). Zander and Reimer (2002) reported a distribution range of R. ovata at a salinity below 8PSU in the Baltic Sea.…”