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Rocky shore trematodes of the west coast of Sweden: distribution and life cycle strategies

100%

Granovitch A. I., Mikhailova N. A.

Acta Parasitologica

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2004

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tom 49

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nr 3

Direct access to intermediate and final hosts is critical for successful trematode life cycle completion. The harsh environmental conditions of the wave-exposed rocky shores of the Swedish west coast seriously hamper trematode transmission. Limited numbers of potential host species are another obstacle for survival. In this case, paraxenia, or the ability of parasites to simultaneously use multiple host species, is of utmost importance in promoting distribution in a wide range of microhabitats. Our purpose was to examine trematode spatial distribution and life cycle strategies under these severe conditions in order to assess specific life history patterns linked to their transmission. Estimation of overall parasitological load was carried out by extensive sampling of all available potential hosts in a wide range of microhabitats (rock pools, rock surfaces, cracks and crevices) from lower to upper littoral levels on the rocky shores of two islands in the Skagerrak Strait, Saltö and Ursholmen. Log-linear analysis was performed separately for sporocysts and metacercariae to evaluate parasite prevalence and intensity values for the second intermediate snail host Littorina saxatilis. A detailed study of the spread of Renicola spp. metacercariae using randomly amplified polymorphic DNA technique revealed two additional previously unreported second intermediate hosts (L. littorea and L. saxatilis) for R. thaidus. Several interesting combinations of transmission patterns were noted demonstrating species plasticity in terms of host use.

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Recovery of macrobenthic assemblages following experimental sand burial

84%

Yanez B., Carballo J. L., Olabarria C., Barron J. J.

Oceanologia

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2008

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tom 50

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nr 3

391-420

Periodic inundation by sand is a very common feature of rocky coasts throughout the world. Even so, there have been few direct observations or experiments to investigate the role of sediments on intertidal rocky shores. We designed a field experiment in Mazatl´an Bay, Mexico, to test the initial impact and subsequent recovery of intertidal macrobenthic assemblages exposed to sand burial at two sites of varying wave exposure. Both sites supported different natural assemblages. Treatment plots for the addition of sediment and control plots (50×50 cm), separated by at least 1.5 m, were randomly placed across the mid-water tidal level. The initial response of the resident macrobenthos and the subsequent recolonization was monitored over a period of 95 days. The main effect of sediment deposition at both sites was mortality and removal of biota due to smothering. The recovery process was rapid and may in part have been the result of the mechanism by which the small, disturbed patches were recolonized. Most of the invertebrates colonized the patches as adults; several seaweeds exhibited vegetative growth as the major mechanism of colonization (e.g., Ulva lactuca Linnaeus, 1753, Amphiroa valonioides Yendo, 1902 and Chaetomorpha antennina (Borgensen) Kutzing, 1849). The rate of recovery varied between the sites, however. Recovery of species numbers proceeded quickly at the sheltered site (day 7), but took 95 days at the exposed site. In contrast, biomass reached control levels by day 45 at the sheltered site, but already by day 15 at the exposed site. By day 95, the assemblages recovered to 83.5% and 81% similarity with the controls at the sheltered and exposed sites respectively. Although differences in wave exposure could be very important in determining the different patterns of recovery at both sites, other biological processes may also play an important part.

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Spring development of hydrolittoral rock shore communities on wave-exposed and sheltered sites in the Northern Baltic proper

67%

Eriksson Wiklund A.-K., Malm T., Honkakangas J., Eklund B.

Oceanologia

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2012

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tom 54

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nr 1

Spring development in the hydrolittoral zone was investigated at five wave-sheltered and five wave-exposed sites on four occasions from late March to late May (every third week). The number of species was higher at the sheltered locations and increased significantly over time. The difference in community structure was significant: over 95% of the Bray-Curtis dissimilarities were due to the biomass of only eleven taxa, and the total Bray-Curtis dissimilarity between exposed and sheltered sites was 75%. Macroalgae made up 70–80% of the total biomass and was dominated by filamentous species. In contrast to previous studies, macroalgal biomass was higher at the exposed sites, which may be due to the fact that this was a spring study, unlike previous studies, which were conducted during summer.

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Predation by drilling gastropods and asteroids upon mussels in rocky shallow shores of southernmost South America: Paleontological implications

51%

Acta Palaeontologica Polonica

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2012

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tom 57

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nr 3

To achieve a better understanding of predation pattern recorded in the fossil record it is essential to study predator−prey interactions in the modern seas. It includes the data collected from the field observations as well as from the experiments in captivity. Such an approach allows recognition of the bioeroders, its description and also provides quantification of these interactions. This work offers a case study of the traces of predation resulting from the predator−prey interactions between three mussels: Mytilus chilensis, Brachidontes purpuratus, and Aulacomya atra; and their five natural enemies: the gastropods Trophon geversianus, Xymenopsis muriciformis, and Acanthina monodon, and the asteroids Cosmasterias lurida and Anasterias antarctica living along the intertidal and/or subtidal rocky shores in Tierra del Fuego. The predatory damage to mussel shells varies according to the predator and prey species and techniques for attacking prey are highly specialized. A. monodon drills a hole in B. purpuratus but uses the outer lip of its shell as a wedge to open the valves of M. chilensis and A. atra. T. geversianus always makes holes, but while it drills the valve walls of M. chilensis, it prefers to drill the valve edges of A. atra and B. purpuratus, with different characteristic patterns. Usually the shells of mussels killed by C. lurida do not suffer from any mechanical damage, but some other shells were crushed or fractured along the margins. Comparatively, time required to successfully attack a prey was shorter in C. lurida (24 hours), followed by A. monodon (36 hours), and longer in T. geversianus (9 to 10 days). Traces of predation are not randomly distributed across size classes of mussel prey, reflecting selectivity for a particular size class. Also, drill holes are usually placed at specific sectors of the shell, indicating site selectivity. These observations offer some paleontological implications for investigating the pattern of predation in fossil record. They show that different patterns of shell damage can be due to different predator species (e.g., wall vs. edge drillings), although the same predator species can leave different marks when consuming different prey (e.g., T. geversianus). Most disconcerting for paleontologists are cases of predation which do not leave any marks on the prey shell detectable in the fossil record (e.g., predation by asteroids), or leave ambiguous marks (A. monodon when preying with the spine). In conclusion, besides the opportunity to identify some traces of predation by drilling gastropods in fossil mussels, this work gives criteria to address predation in some particular paleontological cases that would otherwise be dismissed by researchers.

Ograniczanie wyników

2 Oceanologia

1 Acta Palaeontologica Polonica

1 Acta Parasitologica

1 Barron J. J.

1 Carballo J. L.

1 Eklund B.

1 Eriksson Wiklund A.-K.

1 Granovitch A. I.

1 Honkakangas J.

1 Malm T.

1 Mikhailova N. A.

1 Olabarria C.

1 Yanez B.

2 2012

1 2008

1 2004

Rocky shore trematodes of the west coast of Sweden: distribution and life cycle strategies

Recovery of macrobenthic assemblages following experimental sand burial

Spring development of hydrolittoral rock shore communities on wave-exposed and sheltered sites in the Northern Baltic proper

Predation by drilling gastropods and asteroids upon mussels in rocky shallow shores of southernmost South America: Paleontological implications