Diel and tidal effects on surf zone fish fauna in Southern Brazil


447Lat. Am. J. Aquat. Res., 38(3): 447-460, 2010
DOI: 10.3856/vol38-issue3-fulltext-9

Research Article

Diel and tidal variation in surf zone fish assemblages of a sheltered beach in
southern Brazil


Fabiana C. Félix-Hackradt1, Henry L. Spach1, Pietro S. Moro2, Helen A. Pichler1, Aline S. Maggi1,
Maurício Hostim-Silva3 & Carlos W. Hackradt4
1Departamento de Ecología e Hidrología, Universidad de Murcia, Campus Espinardo, 30100 Murcia, Spain
2Universidade Federal do Ceará-UFC., Av. da Universidade 2853, 60020-181 Fortaleza, Ceará, Brazil
3Universidade Federal do Espírito Santo, Departamento de Ciências da Saúde, Biológicas e Agrárias
Rua Humberto de Almeida Francklin 257, 29933-415 São Mateus, Espirito Santo, Brazil
4Instituto Nautilus de Pesquisa e Conservação da Biodiversidade, Av. Senador Souza Naves 655, 80050-040
Curitiba, Paraná, Brazil



ABSTRACT. Diel and tidal variations of fish assemblages were assessed at Pontal beach, southern Brazil,
using a seine net. Species richness was greater at night, whereas fish number, weight, and richness
(community indicators) were all influenced by the tidal state. Samples from rising tides were more
representative, probably due to onshore fish movements for feeding purposes. However, lower catches were
associated with high tides, mainly through net avoidance, indicating that sampling in these conditions is not
highly informative. Clupeoids exhibited greater variation in a 24 h period, and the night occurrence of A.
tricolor and daylight shoaling of Harengula clupeola, Anchoa parva and Sardinella brasiliensis suggested
distinct strategies for avoiding daylight predators. In some species, this behaviour may have been induced by
the bottom morphology and tidal state, facilitating nearshore grouping. In addition to being caught at night, the
occurrences of Menticirrhus littoralis, Pomadasys corvinaeformis, Umbrina coroides and Hyporhamphus
unifasciatus indicated a spatial niche partition according to tidal state. Although not evaluated properly,
temporal fluctuations could reflect species recruitment patterns. Seasonal fluctuations have to be considered
when analysing short-term changes in the community as such fluctuations are synchronized with the natural
history of the species, making it difficult to interpret short-term variations in isolation.
Keywords: diel cycle, tidal dynamics, species pattern, predators, shoals, southern Brazil.


Variación diaria y mareal de ensambles de peces en la zona de surf de una playa
protegida en el sur de Brasil

RESUMEN. Se utilizó una red de arrastre para evaluar la variación diaria y mareal del ensamble de peces en
la playa de Pontal, sur de Brasil. Se encontró la mayor riqueza de especies durante la noche mientras que la
abundancia, peso y riqueza (indicadores de la comunidad) fueron influenciados por la marea. Las muestras de
marea creciente fueron las más representativas debido probablemente a los movimientos costeros con fines
alimentarios; sin embargo, las menores capturas estuvieron asociadas a pleamares debido a la evasión a la red,
indicando que los muestreos en estas condiciones son poco informativos. Los clupeidos fueron los peces que
más variaron durante un periodo de 24 h; la ocurrencia nocturna de A. tricolor y el agrupamiento matutino de
Harengula clupeola, Anchoa parva and Sardinella brasiliensis sugieren distintas estrategias en la evasión de
los depredadores diurnos. La morfología del fondo asociada con la marea, puede haber influenciado el
comportamiento de algunas especies, facilitándoles el agrupamiento costero. Además de haber sido capturadas
por la noche, la ocurrencia de Menticirrhus littoralis, Pomadasys corvinaeformis, Umbrina coroides and
Hyporhamphus unifasciatus indicó la repartición espacial del nicho según el estado de la marea. Aunque no
evaluadas correctamente, las fluctuaciones temporales pueden reflejar los patrones específicos de
reclutamiento; la estacionalidad debe ser incluida cuando se estudian desplazamientos de corto plazo en la
comunidad debido a su sincronización con la historia natural de las especies, haciendo que las variaciones de
corto plazo sean difíciles de interpretar por sí solas.

Lat. Am. J. Aquat. Res.


448
Palabras clave: ciclo diario, dinámica mareal, patrones específicos, depredadores, cardúmenes, sur de Brasil.

________________________
Corresponding author: Fabiana C. Félix Hackradt (felixhackradtfc@gmail.com)

INTRODUCTION
Studies of fish assemblages in surf zones can provide
not only information of the temporal structure of
populations on both seasonal and diel basis, but also
of the life-history phases that occupy the surf zone
habitats. However, in such dynamic environment it is
difficult to compare studies due to possible seasonal
and diel differences in sampling effort, or gear
susceptibility of different life stages (Ross, 1983). In
general, seasonal changes in surf zone ichthyofaunas
are characterised by low abundance and diversity
during winter and the opposite pattern during warmer
months (Fox & Mack, 1968; Naughton & Saloman,
1978; Modde & Ross, 1981; Allen, 1982; Ross, 1983;
Lasiak, 1984b). These trends suggest that surf zone
habitats may be briefly used by fish moving along the
coast through passes into more protected waters, or by
species that remain in the outer beach system for
longer periods (Ross, 1983).
Short-term changes in abundance occur mainly due
to the tidal cycle, moon phase, and alternation of night
and day (Oliveira-Neto et al., 2004). Many studies
have found different patterns of fish habitat use, with
greater daytime catches (Allen, 1982; Nash & Santos,
1998; Rooker & Dennis, 1991) and higher number of
species and diversity during the night (Livingston,
1976; Nash & Santos, 1998; Lin & Shao, 1999). Nash
(1986) and Gibson et al. (1996) concluded that
community structure variation is strongly influenced
by the dominant species peculiarities and as a
consequence, failed to find a clear periodic pattern.
In this context, the present work aims to investigate
the diel variability of the structure of a surf-zone fish
community on a sheltered beach in southern Brazil.
The study was carried out over a one-year period and
emphasized the description of the patterns of variation
of the most abundant species.
MATERIAL AND METHODS
Study site
Pontal do Sul is a sheltered sandy beach that is
influenced by Ilha do Mel (island), which is located at
Paranaguá estuary mouth. In addition, submerged
channels created by ebb and flood tides reduce the
incidental wave energy (Fig. 1). The beach is
microtidal with two ebb tides per day. According to
Godefroid et al. (1997) who investigated surf zone
fishes on the same beach using different fishing gears,
this beach is classified as dissipative due to the fine to
medium sediment grain sizes, flat slope and medium
wave heights. The weather is classified as subtropical
humid with a warm and wet summer (December to
February) and an undefined dry season (Maack, 1981),
usually considered winter (June to August).
Furthermore, spring and autumn months are defined as
from September to November and March to May,
respectively.
Sampling
The surf zone of Pontal beach, Paraná, Brazil, was
extensively studied from August 2004 to June 2005.
Bimonthly over a period of six months, three seine
hauls were performed at 3 h intervals for 24 h on each
sampling date. Due to weather conditions, April
samples were postponed to the following month, May.
Sampling occurred during spring tides at 8, 11, 14, 17,
20, 23, 2 and 5 h, in order to coincide with high, mid-
falling, low and mid-rising tides, but this pattern could
not always be followed. According to the day length,
four samples were collected in daylight and other four
at night-time during the entire studied period. All
these samplings were considered replicates.
All hauls covered a 30 m extension and were
separated by 5 m to minimize the influence on the
subsequent haul. A 15 m x 2.6 m seine net, with 2 m2
bag and 0.5 cm2 mesh throughout was used to collect
the ichthyofauna. The net was laid parallel to the shore
at approximately 1.5 m depth of water between 10 and
30 m offshore, and was hauled by two people, one on
each end of the net, following the direction of the
current.
All fish collected were identified to species level
following Fischer (1978), Figueiredo & Menezes
(1978, 1980, 2000), Menezes & Figueiredo (1980,
1985) and Barletta & Corrêa (1992). These fishes
were then weighted (g) and measured to the nearest 1
mm (total length and standard length), except when
samples were very large. In these occasions,
measurements were restricted to a sub-sample of 30
individuals per species. The excess was weighted,
counted and incorporated as weight and number
counts. In addition, sex (male, female or not
identified) and maturity stages were documented for
the sub-sample through direct observation, according