Spatial and Temporal Distribution of the Shrimp Nematopalaemon Schmitti
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Journal of the Marine Biological Association of the United Kingdom, 2009, 89(8), 1581–1587. # Marine Biological Association of the United Kingdom, 2009 doi:10.1017/S0025315409990439 Spatial and temporal distribution of the shrimp Nematopalaemon schmitti (Decapoda: Caridea: Palaemonidae) at a subtropical enclosed bay in South America vivian fransozo1, antonio lea~o castilho1,fu’ lvio aure’lio morais freire1,2, michele furlan1, aria’ dine cristine de almeida1, gustavo monteiro teixeira1 and juan antonio baeza3,4,5 1NEBECC (Crustacean Biology, Ecology and Culture Study Group), Departamento de Zoologia, Instituto de Biocieˆncias, Universidade Estadual Paulista, 18.618.000—Botucatu, SP, Brazil, 2Departamento de Cieˆncias Animais, Universidade Federal Rural do Semi-A´ rido, 59625-900, Mossoro´, RN, Brazil, 3Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Balboa, Anco´n, Republic of Panama, 4Smithsonian Marine Station at Fort Pierce, 701 Seaway Drive, Fort Pierce, Florida 34949, USA, 5Departamento de Biologı´a Marina, Facultad de Ciencias del Mar, Universidad Cato´lica del Norte, Larrondo 1281, Coquimbo, Chile The spatio-temporal distribution of the soft bottom dwelling shrimp Nematopalaemon schmitti and the effect of environ- mental conditions (sediment characteristics, temperature, salinity and dissolved oxygen) on its abundance were studied at Ubatuba Bay, south-eastern coast of Brazil. Surveys were conducted monthly from September 1995 to August 1996. Each sampling set comprised eight different transects distributed within the bay. Comparisons of CPUE of shrimp among sampling stations demonstrated that the abundance of N. schmitti was the greatest during winter, when average water temperature within the bay was considerably lower than during the rest of the year. Most shrimps (more than 95%) were collected at a single transect located at the northernmost side of the bay, demonstrating the extremely patchy distribution of this species. A multiple regression analysis using data only from this northernmost transect indicated that temperature was the most relevant factor affecting the abundance of N. schmitti during the year. Keywords: distribution, abundance, temperature, shrimp, Ubatuba Bay, Brazil Submitted 2 March 2009; accepted 5 May 2009; first published online 3 August 2009 INTRODUCTION 1998; Fransozo et al., 2002; Costa et al.,2007:Artemesia long- inaris Bate, 1888—Fransozo et al., 2004; Costa et al., 2005a: Studies on the distribution, abundance, and population Pleoticus muelleri (Bate, 1888)—Costa et al., 2004: Arenaeus cri- dynamics of marine organisms are most relevant given the brarius (Lamarck, 1818)—Pinheiro et al., 1994: Callinectes pervasive effects of habitat degradation, alteration, and con- danae Smith, 1869—Chacur & Negreiros-Fransozo, 2001). tamination on tropical and temperate areas around the These studies suggest that the combined effect of temperature, world. Among crustaceans, most of these studies have been sediment composition, and organic matter availability is most conducted in intertidal and shallow subtidal species from relevant in determining the distribution of crustaceans inhab- hard bottom environments (Jensen & Armstrong, 1991; iting soft bottom environments (Buchanan & Stoner, 1988; Nucci et al., 2001; Caillaux & Stotz, 2003; Takeda et al., Costa et al., 2005a, b; Fransozo et al., 2005; Henderson et al., 2004; Pallas et al., 2006; Viegas et al., 2007). The distribution 2006; Castilho et al.,2008a,b). and conditions explaining the abundance of crustaceans from The white belly shrimp Nematopalaemon schmitti (Holthuis, soft bottom habitats and environments deeper than 10 m are 1950) is found from Venezuela to Brazil in marine and estuar- much less known. ine waters, from very shallow depths up to 75 m (Holthuis, The south-eastern Brazilian coast might be considered one 1980). This species is not commercially exploited given its out of a few localities in the southern hemisphere where inten- small size, but it may play an important ecological role within sive efforts to understand the distribution of soft bottom crus- the trophic web of soft bottom environments to which it per- taceans have taken place. Most of the studies on this coast have tains. Nematopalaemon schmitti is one of several by-catch focused on species of economic importance (Xiphopenaeus species in fisheries targeting large penaeid shrimps, including kroyeri (Heller, 1862)—Nakagaki & Negreiros-Fransozo, Farfantepenaeus paulensis (Perez-Farfante, 1967), F. brasiliensis (Latreille, 1817), Litopenaeus schmitti (Burkenroad, 1936), and Xiphopenaeus kroyeri (Heller, 1862). Nevertheless, the biology of this shrimp is poorly known. Corresponding author: J.A. Baeza The aim of the present study was to characterize the tem- Email: [email protected] poral and spatial distribution of Nematopalaemon schmitti in 1581 1582 vivian fransozo et al. a subtropical semi-enclosed bay located in the south-eastern Shrimp collection and transect description Atlantic. We also attempted to identify those environmental conditions, namely, temperature, salinity, dissolved oxygen, To describe the spatio-temporal distribution of N. schmitti at and sediment characteristics, explaining the abundance of Ubatuba Bay, shrimp samples were collected monthly from this shrimp at small temporal scales (within a year) at the September 1995 to August 1996 using a fishing boat carrying study site. two otter-trawl nets (3.5 m wide; 15 mm and 10 mm mesh diameter at the body and cod end of the net, respectively). A total of 8 permanent transects were established within the outer (I, II, III and IV) and inner area (V, VI, VII and VIII) MATERIALS AND METHODS of the bay (Figure 1). During sampling, each transect was trawled for 1 km (each trawl lasted 30 minutes). Each month, sampling was conducted during three consecutive Study site 2 days and covered a total area of 7 km . Shrimps captured Ubatuba Bay (238250S0 458030W), located on the northern during each trawl were immediately stored in ethanol (70%) coast of Sa˜o Paulo State, Brazil, faces eastward, and it is shel- and transported to the laboratory where they were counted. tered from southern and south-western waves coming from During trawling, water samples taken with Nansen bottles the open sea (Burone & Pires-Vanin, 2006). This bay can be were used for measuring dissolved oxygen, salinity and temp- divided in a protected inner area (intertidal to 10 m, low erature at the different stations. For dissolved oxygen esti- hydrodynamic energy) and an outer more exposed area mations, we employed the modified Winkler method that (10–16 m). Within the bay, five sandy beaches are flanked included the addition of azide (Golterman & Clymo, 1969). by rocky shores (Figure 1). Freshwater from four small Sediment was collected at each transect with a 0.06 m2 Van rivers (Indaia´, Grande, Lagoa and Acarau´) originating from Veen grab. Samples were transported to the laboratory and the Atlantic coastal forest (Mata Atlaˆntica) as well as smaller oven-dried (70ºC for 72 hours). Grain size composition of streams from surrounding mangrove-dominated areas flow the different samples was analysed following the protocols into the bay. The effect of this freshwater discharge is the of Hakanson & Jansson (1983) and Tucker (1988). In short, occasional decrease in salinity in the shallow areas of the bay. two sub-samples of 50 g were treated with 250 ml of NaOH Fig. 1. Ubatuba Bay, indicating the sampling transects (In, inner bay; Out, outer bay). distribution of a soft bottom shrimp 1583 (0.2 mol/l) and stirred for 5 minutes. This procedure resulted version 9.1 (SAS Institute, 2004). Because sample size was in the release of silt and clay particles. Next, sub-samples were small (the ratio of observations to model parameters was rinsed in a 0.063 mm sieve. Sediments were sieved again less than 40), the corrected AIC (AICc) was used to select through a series of meshes with different diameters; 2 mm between models (Burnham & Anderson, 2002). The model (for gravel retention); 2.0–1.0 mm (very coarse sand); with the lowest AICc value (the best-fitting and most parsimo- 1.0–0.5 mm (coarse sand); 0.5–0.25 mm (medium sand); nious model) was selected as the best model. Lastly, we deter- 0.25–0.125 mm (fine sand) and 0.125–0.063 mm (very fine mined the effect of each variable contained in this best model sand). Smaller particles were classified as silt–clay. on the abundance of the shrimp. Cumulative particle-size curves were plotted using the Phi scale. Phi values were calculated using the formula w ¼ –log2d, where d ¼ grain diameter (mm). The mean RESULTS diameter (MD) of sediment samples was determined from these Phi values (corresponding to the 16th, 50th and 84th Ubatuba Bay was characterized by moderate changes in temp- percentiles) using the formula MD ¼ (w16 þ w50 þ w84)/3 erature and salinity throughout the year. Average temperature (Suguio, 1973). Sediment texture was examined visually by was greater during summer and autumn than during spring plotting triangular diagrams using the three granulometric and winter (Figure 2). In turn, average salinity was rather con- classes with the highest proportions (Magliocca & Kutner, stant through the year other than during spring where it 1965). Granulometric Class A corresponds to sediments in decreased all along the bay (Figure 2). Sediment grain compo- which intermediate sand (IS), coarse sand (CS), very coarse sition remained almost the same throughout the year at each sand (VCS) and gravel (G .