Original Article Rodrigues dos-Santos et al.: Serranidae larvae in the SoutheasternBJOCE Brazilian Bight Composition and distribution of Serranidae (Actinopterygii:Perciformes) larvae in the Southeastern Brazilian Bight Mariana Rodrigues dos-Santos1* , Mario Katsuragawa1, Maria de Lourdes Zani-Teixeira1, Jana Menegassi del Favero2 1 Instituto Oceanográfico da Universidade de São Paulo, Laboratório de Biologia e Ecologia do Ictioplâncton Marinho (Praça do Oceanográfico, 191, 05508-120 - São Paulo - SP - Brazil) 2 Instituto Nacional de Pesquisas Espaciais, Divisão de Sensoriamento Remoto (Av. dos Astronautas, 1758, 12227-010 - São José dos Campos - SP - Brazil) *Corresponding author: [email protected] ABSTRACT This study describes the taxonomic composition and horizontal distribution of Serranidae larvae along the Southeastern Brazilian Bight (SBB, approximately 22°S and 28°S), and investigates how environmental and biological factors influence the larval distribution. Ichthyoplankton samples were collected in 10 oceanographic cruises conducted from 1975 to 1981. Serranidae larvae were identified into 15 species, including 11 genera and four subfamilies. Except for Diplectrum formosum, which was widely distributed throughout the SBB, Hyporthodus spp. and Baldwinella vivanus were distributed in the southern portion of the SBB, while other species were distributed mainly in the northern portion of the SBB, inside the 200 m isobath. Local depth, latitude, distance from the closest island and salinity were factors that influenced significantly on the distribution and abundance of the most abundant taxa D. formosum, Diplectrum spp., Serranus spp. and Mycteroperca spp. Significant progress was made in identifying grouper larvae from the SBB (Epinephelus morio, Epinephelus itajara and Hyporthodus nigritus). Descriptors: Anthiadinae, Epinephelinae, Ichthyoplankton, Serraninae. INTRODUCTION They have high longevity (e.g. Epinephelus itajara lives approximately 37 years, according to Bullock et al. Serranids (e.g. groupers) are economically and eco- (1992) and Bueno et al. (2016)), relatively slow growth logically important (e.g. Heemstra et al., 2002; Craig et and late maturation (Heemstra and Randall, 1993; Bueno al., 2011). According to Fricke et al. (2019), there are ap- et al., 2016). They are synchronic or protogynous her- proximately 571 valid species of serranids in the world, maphrodites (Sadovy and Shapiro, 1987; Heemstra and divided into five subfamilies (Serraninae, Anthiadinae, Randall, 1993; Bezerra and Silva, 2011). In addition, the Epinephelinae, Grammistinae and Liopropomatinae). formation of large reproductive aggregations at speci- Along the Brazilian coast, Menezes et al. (2003) and fic sites during certain periods of the year contributes to Bonecker et al. (2014) reported approximately 50 spe- making them more susceptible to overfishing (Helfman cies comprised of 18 genera and five subfamilies. In the et al., 2009; Bezerra and Silva, 2011). Thus, some spe- Southeastern Brazilian Bight (SBB), there are about 38 cies of serranids are listed by the International Union for species of serranids (data based on Froese and Pauly, Conservation of Nature (IUCN, 2019) as: (i) critically en- 2018). dangered (e.g. Epinephelus striatus), (ii) vulnerable (e.g. Epinephelus itajara, Hyporthodus niveatus, Mycteroperca microlepis) or (iii) at low risk/ near threatened (e.g. Submitted on: 24/April/2019 Hyporthodus nigritus, Paralabrax dewegeri). Approved on: 29/April/2019 It is always the concern of the species future and its http://dx.doi.org/10.1590/S1679-87592019026406701 preservation that leads researchers and scientists to deepen BRAZILIAN JOURNAL OF OCEANOGRAPHY. 2019;v67:e19264 1 Rodrigues dos-Santos et al.: Serranidae larvae in the Southeastern Brazilian Bight their knowledge of the biological and ecological aspects São Francisco do Sul Island (SC) and Santa Catarina Island of adults. However, to understand these aspects, it is ne- (SC); smaller islands usually located inside bays, and archi- cessary to know about the early life stages cycle (Leis and pelagos, such as Alcatrazes Archipelago (SP) (Castro et al., Trnski, 1989; Katsuragawa et al., 2006). Nevertheless, be- 2006) (Figure 1). These islands constitute a site of great biolo- fore studying a species early life cycle, it is necessary to gical diversity and marine biomass, especially for endangered identify its eggs and larvae. species, which find shelter and suitable places for feeding and Descriptions of larval development are essential for reproduction (Luiz Jr et al., 2008). ichthyoplankton identification. Focusing on serranids, it is The Brazil Current (BC), a west contour current as- relevant to cite Kendall Jr. (1979), who described larval sociated with the South Atlantic Subtropical Gyre, de- stages from 17 of the 23 genera that occur in the Pacific termines the hydrodynamics of the region. According to and Atlantic coasts of the United States; and Johnson Silveira et al. (2000), it is responsible for the transport of and Keener (1984) about the morphology of the elonga- five water masses, among which the following are rele- ted spines of the Epinephelini tribe larvae. Other authors vant in this work: Tropical Water (TW), with temperatu- also collaborated to describe serranid larval stages, such res higher than 20ºC and salinity higher than 36.4; South as Baldwin (1990) (Anthiadinae subfamily), López et Atlantic Central Water (SACW) with temperature lower al. (2002) (Diplectrum radiale), and Cunha et al. (2013) than 20ºC, salinity between 34.6 - 36, and nutrient rich; (Epinephelus marginatus). and Coastal Water (CW), characterized by lower salinities There is a lack of studies on serranid larvae at a speci- as a result of mixing of the shelf water with continental fic level in Brazil (e.g. Katsuragawa et al., 2006; Bonecker waters (Campos et al., 1996; Silveira et al., 2000). et al., 2012; Macedo-Soares et al., 2014; Bonecker et al., There are records of waters close to the coast wi- 2014; Katsuragawa et al., 2014; Bonecker et al., 2019). In th temperatures below 18ºC associated with the coastal these studies, it was only possible to identify the majority upwelling of SACW in the region of Cape Frio (RJ) and of the larvae to genus, confirming the difficulty of identi- Cape Santa Marta Grande (SC). This upwelling occurs se- fying the larvae of Serranidae in Brazilian waters. asonally, between spring and summer (Castro et al., 2006). The aim of this study was to contribute to improve The cold water upwelled in Cape Frio (RJ) moves towards the knowledge about the taxonomic composition and the the southeast, reaching even the vicinity of São Sebastião distribution of the serranid larvae in the SBB and discuss Island (SP) in some years (Pereira et al., 2009). how environmental and biotic factors can influence their distribution. Data collection and sample preparation Zooplankton samples were collected during 10 oce- MATERIAL AND METHODS anographic cruises conducted from December 1975 to January 1981, between Cape Frio (23°S) and Cape Santa STUDY AREA Marta Grande (roughly 29°S). A total of 1,113 oceano- The coastline extension of the Southeastern Brazilian graphic stations were sampled. The stations were distri- Bight (SBB), is about 1,100km, including the region be- buted over the neritic zone from the coast out to the shelf tween Cape Frio - RJ (23ºS) and the Cape Santa Marta break. On some cruises, some extra stations were done in Grande - SC (28º40’S) (Figure 1) (Castro et al., 2006). two transects up to approximately 260km from the coast Its shape resembles a crescent moon, with the narrowest (3,000m isobath), one offC ape Frio (RJ) and one offC ape ends (Cape São Tomé - 50km width and Cape Santa Marta Santa Marta Grande (SC) (Table 1; Figure 1). Grande - 70km width) and a wider central portion (region Hydrographic observations were made at each station. off Santos - 230km width) (Castro et al., 2006; Rohr and Water samples for salinity measurement were collected Almeida, 2006). The shelf break varies from 120 to 180m using Nansen bottles and analyzed with an inductive sali- (Mahiques et al., 2010). The bottom of the SBB is cove- nometer. Reversible thermometers coupled to the Nansen red by sand and muddy sediments, but north of Cape Frio bottles registered the temperature at the surface and at (RJ), sediments of greater particle size (gravel and sands) 10m depth. predominate (Figueiredo Jr. and Tessler, 2004). Zooplankton samples were collected with a bongo net The region presents some larger islands located near the of 0.61m diameter mouth opening, equipped with paired coast (e.g. Grande Island (RJ), São Sebastião Island (SP), cylindrical-conical 0.333mm and 0.505mm mesh size 2 BRAZILIAN JOURNAL OF OCEANOGRAPHY. 2019;v67:e19264 Rodrigues dos-Santos et al.: Serranidae larvae in the Southeastern Brazilian Bight Figure 1. Study area in the Southeastern Brazilian Bight (SBB, approximately between 22ºS and 28ºS), between December of 1975 and January of 1981. The black stars represent 14 islands: (1) Cagarras Parcel, (2) Laje Marambaia, (3) Grande Island, (4) Parcel, (5) Anchieta Island, (6) Mar Virado Island, (7) Búzios Island, (8) Montão de Trigo Island, (9) Alcatrazes Archipelago, (10) Vitória Island, (11) Moela Island, (12) Laje de Santos, (13) Queimada Grande Island and (14) Bom Abrigo Island. Table 1. Oceanographic cruise number, period and a number nets, following Smith and Richardson (1977). In this stu- of oceanographic stations analyzed in the present study. dy, only the 0.505mm mesh size samples were analyzed. Cruise Period Stations The bongo nets were towed obliquely from the surface to FINEP 1 December 1975 140 the maximum depth possible, not exceeding 200m depth. FINEP 2 January 1976 140 At sites with less than 60m depth, the oblique tow was re- FINEP 3 May 1976 140 peated to increase the volume of water filtered through the net. A flowmeter was attached at the center of each mouth- FINEP 4 September 1976 140 -opening bongo net to measure the filtered water volume. FINEP 5 December 1976 140 The method proposed by Kramer et al. (1972) was used in FINEP 6 January 1977 112 order to obtain the volume of zooplankton sampled.