Marine invertebrates associated with rhodoliths/maërl beds from northeast Brazil (State of Paraíba)

Abstract

This study investigates the marine macroinvertebrate fauna of rhodolith beds (non-geniculated red corallinaceaous algae) in northeast Brazilian. A total of 57 species were identified, belonging to six phyla (Platyhelminthes, Annelida, Sipuncula, Mollusca, Arthropoda and Echinodermata), of which 50 are considered here as new records for the Paraíba State. Annelids (Class Polychaeta) were the most representative taxa in Miramar and Seixas Beaches, while molluscs were dominant in Maceió Beach. This is the first study that includes an identification key, diagnostic features and distribution patterns worldwide and local (including new records) of the marine invertebrate fauna associated with rhodolith beds in northeast Brazil (State of Paraíba). Sampling events were performed in 2018, at low tide in the intertidal to shallow subtidal zones (1.5 and 4.0 m depth), in Miramar, Seixas and Maceió Beaches. A total of 17 species were found for the first time on Seixas Beach, as well as all identified species for Miramar and Maceió. This study tries to contribute to the knowledge of marine invertebrates in northeast Brazilian shallow habitats, providing a baseline for future environmental studies.

An Overview of Rhodoliths: Ecological Importance and Conservation Emergency

“…One of the taxonomic groups with a wider geographic distribution range and larger climatic and bathymetric amplitudes include the rhodolith-forming algae [41]. The oceanic photic area is home to both living and dead calcareous structures, which are found from the intertidal zone to depths of 270 m [5,7,17,42].…”

“…Rhodoliths can be divided into three types based on their morphology: boxwork, unattached branches and pralines (Figure 2, e.g., [1,8,41,79]):…”

“…Due to the variety of niches it offers, the rhodolith provides shelter and protection for associated fauna against physical disturbances and predators and allows coexistence [75,85]. Rhodoliths have been recognised as places of the recruitment of marine species, providing refuge for the early stages of growth of commercially significant fishes [17] and for several species of marine invertebrates [17,82,[86][87][88][89], such as polychaetes, bivalves, molluscs and echinoderms [81,85,[90][91][92]. A rhodolith's internal space may further contain particles of organic matter for filtering organisms and may provide microphytobenthos for herbivorous scavengers [93].…”

“…[12,21,44,53]. The similar ecological niches of L. corallioides and P. calcareum are influenced by environmental drivers, such as wave motion and seabed currents-resulting from rivers, tides and salinity differentials-and the interaction between depth, light accessibility and water quality in general [21,41,138,139]. These coralline algae are typically better adapted to low-energy oceanographic environments (they usually do not occur when exposed to strong wave activity), more frequently found in coves and bays [21].…”

“…,[8,80,81]):(a) Warty growth: branches can be cylindrical or compact, and are typically organized radially; (b) Lumpy growth: protuberances are enlarged, numerous and contiguous and rarely branched; (c) Fruticose growth: branches are remarkably detached from each other.…”