Marine Environmental Research 161 (2020) 105129 Contents lists available at ScienceDirect Marine Environmental Research journal homepage: http://www.elsevier.com/locate/marenvrev Ghost fishing impacts on hydrocorals and associated reef fish assemblages T.M. Beneli a, P.H.C. Pereira b, J.A.C.C. Nunes a,c, F. Barros a,d,* a Laboratorio´ de Ecologia Bentonica,^ CIENAM, PPGEcologia, Instituto de Biologia, Rua Barao~ de Geremoabo s/n., Campus Ondina, Universidade Federal da Bahia, CEP 40170-115, Salvador, BA, Brazil b Projeto Conservaçao~ Recifal (PCR), Recife-Brasil. PC Maciel Pinheiro, 369 - Sala 01, Boa Vista. Recife, PE, Brazil c Reef Ecology Group, N42, CEP, 40155-010, Salvador, BA, Brazil d Instituto Nacional de Ci^encia e Tecnologia em Estudo Interdisciplinares e Transdisciplinares em Ecologia e Evoluçao~ (INCT IN-TREE), Brazil ARTICLE INFO ABSTRACT Keywords: Ghost fishingis a threat to many marine environments, as lost or discarded fishinggear (e.g., fishinglines, nets) Fire-coral continues to fishby entangling, damaging or killing various organisms. Among the benthic organisms that live on Fishing line tropical reefs, the group probably most affected, due to their shape, are the branching corals. These corals Coral mortality provide refuge, foraging and breeding sites, especially for fishes and therefore impacts on coral structure could Fish behavior compromise the ecology of associated species. We tested if fishing lines entangled on the branching coral Mil­ Habitat degradation Coral-fish interaction lepora alcicornis would result in an increase in colony mortality, decrease in abundance and richness of fishesand changes in the behavior of associated reef fish.In the field,we estimated the volume of M. alcicornis colonies and its mortality percentages, and videos were recorded to evaluate abundance and richness of fishassemblages and fish behavior. Our results showed that coral mortality increased with increasing amounts of entangled fishing lines. Fish assemblages were similar in M. alcicornis colonies with or without entangled fishing lines. Never­ theless, we observed a significant decrease in the frequency of feeding attempts in two herbivore fish species (Acanthurus bahianus and Ophioblennius trinitatis) that play an important role in coral-reef dynamics, controlling algae abundances. Therefore, ghost fishing has negative impacts on shallow reef ecosystems, directly affecting branching corals and important coral-fish interactions. Management of tropical shallow reef environments should consider regulation and monitoring of coastal fisheries to ensure reef integrity. 1. Introduction ghost fishing on sessile invertebrates (Chiappone et al., 2005) and its interactions with fish are virtually unknown. Ghost fishing is the term used when fishing gear that is abandoned, Lost fishinglines entangled on branching corals might damage their discarded or lost, continues to fish or to exert negative effects (e.g. fragile polyps and tissue or even literally rip away branches (Asoh et al., entanglement, ingestion, death) on marine organisms (Gilman et al., 2004; Chiappone et al., 2005; Valderrama Ballesteros et al., 2018). 2016; Matsuoka et al., 2005). Many lost fishing gears, such as traps, When the injury is severe, coral recovery may become debilitated, fishing nets, and lines, can persist in the sea for centuries due to their compromising their survival (Matsuoka et al., 2005; Yoshikawa and resistant and non-bio-degradable composition (Brown and Macfadyen, Asoh, 2004). However, the effects of ghost fishing on branching corals 2007). Ghost fishingeffects on marine megafauna (e.g. turtles, dolphins, have not yet been fully addressed and could be underestimated. whales) are very well known and widely publicized and it has been Branching corals are very important in coral reefs around the world suggested that ghost fishing mortality can affect fish stock assessment due to their complex and delicate architectural structure. The branching models (Gilman, 2015; Gilman et al., 2016). The impacts can also affect hydrocoral species of the genus Millepora are abundant in the South benthic habitats, for instance by damaging benthic communities on Atlantic Ocean, therefore, it is an important habitat-builder on south- vulnerable and significant coastal ecosystems such as coral reefs and western Atlantic reef systems (de Souza et al., 2017). Millepora com­ seagrass beds (Gilman, 2015; Shester and Micheli, 2011; Yoshikawa and plex tridimensional structure provides habitat and resources for many Asoh, 2004). Nevertheless, studies regarding the potential effects of marine invertebrates and fishes, resulting in complex patterns of * Corresponding author. Laboratorio´ de Ecologia Bentonica,^ CIENAM, PPGEcologia, Instituto de Biologia, Rua Barao~ de Geremoabo s/n., Campus Ondina, Uni­ versidade Federal da Bahia, CEP 40170-115, Salvador, BA, Brazil. E-mail address: [email protected] (F. Barros). https://doi.org/10.1016/j.marenvres.2020.105129 Received 23 June 2020; Received in revised form 21 August 2020; Accepted 22 August 2020 Available online 27 August 2020 0141-1136/© 2020 Elsevier Ltd. All rights reserved. T.M. Beneli et al. Marine Environmental Research 161 (2020) 105129 biological interactions (Coni et al., 2012; Garcia et al., 2008; Leal et al., assemblages dominated by turf algae, zoantharians, sponges and echi­ 2015, 2013; Lewis, 2006; Pereira et al., 2012). Large branching coral noderms (Ferreira et al., 2015). Other abundant benthic organisms colonies (i.e. high volume) exhibit large abundances and high richness found in the area ascidians and coral colonies of Favia gravida, Agaricia associated fishassemblages (Agudo-Adriani et al., 2016; Counsell et al., agaricites, Montastraea cavernosa, Mussismilia hispida, Siderastrea spp., 2018; Johnson et al., 2011; Leal et al., 2015; Pereira and Munday, 2016). and fire corals (Millepora spp.) (Ferreira et al., 2015). Reefs at the TSB Nevertheless, branching corals are likely among the most affected entrance are exploited by human activities such as artisanal fisheries, benthic group by hooks and fishing lines (Chiappone et al., 2005). marine ornamental trade and spearfishing, mostly because it is located Reef fish assemblages are broadly affected by the loss of live corals within the great urban center of Salvador city (Ferreira et al., 2015; (e.g. Lokrantz et al., 2009; Bonin et al., 2011) and different fishspecies Nunes et al., 2012). may have distinct responses (Wilson et al., 2006). For instance, it is expected that impacts on branching corals will likely affect specificfish 2.2. Ghost fishing on hydrocorals assemblages. These assemblages associated with hydrocorals use the colonies mostly for shelter/refuge (Coni et al., 2012), as territory (e.g. Fieldwork was conducted between June and August 2018 by snor­ territorial herbivores) and as a food source by foraging on colony polyps keling at low tide between 0800 and 1700 h, always with good visibility (Leal et al., 2015, 2013). Hence, fishing lines entangled on hydrocoral (~10 m). A total of 30 colonies of Millepora alcicornis were haphazardly colonies may limit fish use, i.e. if there is loss of shelter or resource sampled, at least 2 m apart. Each colony had their length, width and limitation for fishes that forage among colony polyps. Importantly, the height estimated (cm) using a tape measure. It is well known that presence of resident fishes amid coral colonies could be beneficial for M. alcicornis colonies present a high heterogeneity regarding their shape coral resilience and recovery since they remove competing seaweeds (de Weerdt, 1981; Edmunds, 1999), and that colony volume may have a (Chase et al., 2018; Dixson and Hay, 2012). positive influenceon the abundance and richness of the associated reef Here, we investigate the potential impact of ghost fishing (i.e. fishes( Leal et al., 2015). Therefore, colony volume (m3) was estimated entangled fishinglines) on the branching hydrocoral Millepora alcicornis using the formula V = L. W . H, where L is the length (the longest base and associated reef fish assemblages. We aim to analyze the conse­ axis of the colony), W is the width (orthogonal to the firstand the second quences of ghost fishingon hydrocoral mortality as well as for associated longest base axis) and H is the height (the height measured from the reef fish assemblages. Specifically, we hypothesized that an increase in substrate to the largest branch of the colony) (adapted from Coni et al., fishing lines entangled on M. alcicornis colonies, (i) would increase the 2012; Leal et al., 2015). All measurements were taken manually by the mortality of hydrocoral colonies (M. alcicornis), (ii) would decrease the same person (TMB) (ESM Fig. 1). The same procedure was applied to abundance and richness of associated reef fish assemblages. Addition­ measure the entangled fishinglines in each colony. We used colony and ally, we assessed whether fishing lines in M. alcinornis colonies would fishing line volumes to calculate the proportion of fishing line occu­ change fish behaviors such as sheltering, feeding, agonistic and non- pancy (percentage) in each colony. The mortality of the colonies was occupational swimming. visually estimated by the same observer (TMB) following standard methods (Leao~ et al., 2015). 2. Materials and methods 2.1. Study site 2.3. Reef fish assemblages The present study was conducted at Todos os Santos Bay (TSB), Underwater videos were recorded in all 30 sampled colonies. To Salvador, Brazil