Spatial pattern of hydrolittoral rock encrusting assemblages along the salinity gradient of the Baltic Sea

Abstract

This study compared the diversity parameters and structures of encrusting assemblages in two habitats situated at two levels of shallow rocky shore: hydrolittoral and littoral along the Baltic Sea system. We investigated the variability and level of distinctiveness of the hydrolittoral encrusting fauna based on species biodiversity and distribution, and compared these features with those of communities inhabiting the adjacent shallow littoral zone (3-m depth). Structural similarities and differences between the encrusting assemblages from adjacent hydrolittoral and littoral zones were studied within 14 locations distributed along the northern coastline of the Baltic Sea. Multivariate analysis indicates that salinity had the greatest influence on the structure of the investigated assemblages. Most of the observed hydrolittoral assemblages contained the same species as the littoral zone. This result indicated a shared common species pool with similar large-scale patterns of species distributions with some variability in the dominating species between zones. The similarity between species composition of the hydrolittoral and littoral assemblages decreased with increase of salinity. Additionally, with higher species richness and the occurrence of marine specialists adapted to hydrolittoral conditions, the role of the rock size in the frequency of species occurrence and assemblage diversity was less significant.

First true brackish-water nudibranch mollusc provides new insights for phylogeny and biogeography and reveals paedomorphosis-driven evolution

“…There are several brackish water invertebrates which are common in Scandinavian fjords and particularly in the Swedish Idefjord, including cnidarian hydroid polyp Cordylophora caspia (Pallas, 1771), nemertean Cyanophthalma obscura (Schultze, 1851), polychaete Hediste diversicolor (O.F. Müller, 1776), crustaceans Neomysis integer (Leach, 1814), Gammarus zaddachi Sexton, 1912, Gammarus duebeni Lilljeborg, 1852 and Palaemon varians Leach, 1813 [ 53 – 60 ] and the bryozoan Einhornia crustulenta (Pallas, 1766) [ 61 ]. Some invasive brackish-water species present in the inner part of the Idefjord are the gastropod mollusc Potamopyrgus antipodarum (Gray, 1843) [ 62 ] and the polychaete Marenzelleria viridis (Verrill, 1873) [ 63 ].…”

Local Interactions Affect Spread of Resource in a Consumer-resource System With Group Defense

“…However, other potential factors of heterogeneity not accounted by our analysis are substratum topography [12,21] and resource availability [13]. These factors can be included in our model with spatially variable survival or reproductive functions.…”

Polymorphism ofCaCO3and the variability of elemental composition of the calcareous skeletons secreted by invertebrates along the salinity gradient of the Baltic Sea

“…Barnacles Amphibalanus improvisus and mussels Mytilus spp. are the most widely distributed encrusting calcifiers in the Baltic Sea, typical for littoral and sublittoral bottoms of intertidal and estuarine communities (Grabowska & Kukliński, 2016; Thomsen et al, 2018). They are euryhaline organisms with a geographical salinity range of about 3–40; thus, they inhabit almost the entire coastal region of the Baltic Sea.…”

“…Barnacles Amphibalanus improvisus and mussels Mytilus spp. are the most widely distributed encrusting calcifiers in the Baltic Sea, typical for littoral and sublittoral bottoms of intertidal and estuarine communities (Grabowska & Kukliński, 2016;Thomsen et al, 2018). The Baltic Sea is an isolated marine area and acts as a hybridization zone for Mytilus species that cross-fertilize and create…”

“…It decreases from fully marine values near the North Sea to approximately 7 in the southern region and to almost freshwater conditions at the northern end of the Gulf of Bothnia and at the eastern end of the Gulf of Finland (Bergström et al, 2005; Gustafsson & Westman, 2002; Russell, 1985). Many marine organisms, especially those producing CaCO 3 skeletons, exhibit poor tolerance to reduced salinity and are not able to thrive in brackish environments (Bonsdorff, 2006; Grabowska & Kukliński, 2016; Westerbom et al, 2002; Zettler et al, 2007). Therefore, the Baltic Sea has low calcareous species diversity, which increases towards more saline waters, peaking near the North Sea (Gogina & Zettler, 2010; Zettler et al, 2007).…”