Seasonal abundance of the shipworm Neoteredo reynei (Bivalvia, Teredinidae) in mangrove driftwood from a northern Brazilian beach

Abstract

ABSTRACT. Shipworms are important decomposers of wood, especially in mangrove forests where productivity is high. However, little emphasis has been given to the activity of shipworms in relation to the export of nutrients from mangroves to adjacent coastal areas. As a first step to obtaining such information, the frequency of colonized mangrove driftwood as well as shipworm density and length were studied by collecting washed up logs during a year at Ajuruteua beach, state of Pará, northern Brazil. A single species, Neoteredo reynei (Bartsch, 1920), was found colonizing driftwood. Although large colonized logs were most common on the beach, shipworm density was higher in small logs, especially during the dry season. In general, however, density was higher during the wet season (January to April) and lowest in July. Overall shipworm mean length was 9.66cm. In large logs, mean length increased between the wet and dry seasons. However, there was no difference in length among log size categories. Mean shipworm length was similar throughout most of the year but tended to be greater in July. Although salinity varied between 10.9 and 40 during the year, no relationship was found between salinity and density or length. The results suggest that shipworm activity in driftwood logs is relatively constant throughout the year. Increased air humidity and rainfall may promote survival during the wet season. Large logs may take longer to colonize and thus have lower densities than small ones which are scarce probably because they are destroyed rapidly by shipworm activity. However, data on the disintegration of logs would be necessary to test this hypothesis. Larger size of shipworms in the dry season may be related to growth after an earlier recruitment period. Shipworms in large logs during the dry season may be better protected from dessication and high temperatures by the insulating properties of the larger volume of wood. KEYWORDS.Teredinidae, shipworm, mangrove, driftwood. RESUMO. Abundância sazonal do turuNeoteredo reynei (Bivalvia, Teredinidae) em madeira de mangue à deriva de uma praia da Costa Norte do Brasil. Turus são importantes decompositores de madeira, especialmente em manguezais, onde a produtividade é alta. Entretanto, pouca ênfase tem sido dada à atividade de turus em relação à exportação de nutrientes de manguezais para as áreas costeiras adjacentes. Como um passo inicial para obter tais informações, a freqüência de madeira do mangue à deriva colonizada por turus, bem como a densidade e comprimento de turus, foram estudados através da coleta de troncos encalhados durante 12 meses na praia de Ajuruteua, Estado do Pará, norte do Brasil. Uma única espécie, Neoteredo reynei (Bartsch, 1920), foi encontrada colonizando a madeira à deriva. Embora troncos grandes colonizados fossem mais comuns na praia, a densidade de turus foi maior nos troncos menores, especialmente na estação seca. Em geral, a densidade foi maior durante a estação chuvosa (janeiro a abril) e menor em julho. O comprimento médio geral de turus foi ...

Biodiversity of Shipworms (Mollusca: Bivalvia: Teredinidae) in the Vicinity of a Tropical Mangrove Ecosystem along Bay of Bengal, Andhra Pradesh, India

“…24 Earlier, Natarajan et al 25 also noticed that casuarina poles used in pen-culture at Killai near Chidambaram in Tamilnadu were heavily damaged by marine borers in 6 months. In a recent study on the seasonal abundance of shipworms in mangrove driftwood from a northern Brazilian beach, Filho et al 10 could recover only a single species of teredinid, Neoteredo reynei (Bartsch) from as low as 87 logs out of as many as 720 logs collected. Therefore, absence of other groups of borers as in the present instance, or even other genera/species within a group in the collections, may not be surprising.…”

“…1,2 In order to reduce the material and monetary losses, various aspects of marine wood biodeterioration have been pursued worldwide for long and among them, the recent works of SanchezAlferz & Alferz-Leon, 3 Leonel et al 4 Brearley et al, 5 Santos et al, 6 Brooks, 7 Borges et al, 8 Cragg, 9 Filho et al, 10 Borges et al 11 deal with the occurrence, diversity or distribution of marine wood borers at various geographical localities. Similar efforts have also been put in India for quite some time.…”

Rhizophora stylosa prop roots even when damaged prevent wood-boring teredinids from toppling the trees

“…However, it is thought that sphaeromids are unable to burrow into older developed roots that reach the substratum due to the development of woody tissue in the older roots (Perry, 1988). The development of woody tissue may be an attractive habitat for larval teredinids to settle upon, but teredinids predominantly process dead wood in the mid-to-low intertidal (Filho et al, 2008;Hendy et al, 2013). Increased tidal inundation may then enhance the breakdown of damaged mangrove roots because densities of wood borers become more numerous with longer immersion (Robertson & Daniel, 1989;Svavarsson et al, 2002).…”

Habitat creation and biodiversity maintenance in mangrove forests: teredinid bivalves as ecosystem engineers

“…Teredinids create many tunnels in LWD (Filho, Tagliaro & Beasley, 2008). When the teredinids die, the tunnels may support biodiversity when vacant, for animals to exploit (Cragg & Hendy, 2010; Hendy et al, 2013).…”