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Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
Soft-bottom benthic assemblage changes due
to tropical seasonal upwelling (Bahía Salinas, Costa Rican Pacific)
Jeffrey A. Sibaja-Cordero1,2,*; https://orcid.org/0000-0001-5323-356X
Jorge Cortés1,2; https://orcid.org/0000-0001-7004-8649
Viktoria Bogantes1,2,3; https://orcid.org/0000-0002-9650-5913
Rita Vargas2; https://orcid.org/0000-0003-0561-2121
Kimberly García–Mendez1,2,4; https://orcid.org/0000-0001-7059-1860
1. Centro de Investigación en Ciencias del Mar y Limnología (CIMAR), Ciudad de la Investigación, Universidad de Costa
Rica, San Pedro, 11501–2060 San José, Costa Rica; jeffrey.sibaja@ucr.ac.cr, jorge.cortes@ucr.ac.cr
2. Escuela de Biología, Museo de Zoología, Universidad de Costa Rica, San Pedro, 11501–2060 San José, Costa Rica;
rita.vargas@ucr.ac.cr
3. Department of Biology, University of West Florida, 11000 University Pkwy Pensacola, FL 32514, USA;
vikbogantes79@gmail.com
4. O’Dea Lab, Smithsonian Tropical Research Institute, Panama; kimberly13@gmail.com
Received 04-IX-2024. Corrected 18-XI-2025. Accepted 28-I-2025.
ABSTRACT
Introduction: Seasonal upwelling is a displacement offshore of surface seawater and replacement by cool deeper
water with higher nutrient levels by the influence of the wind. On the north Pacific coast of Costa Rica the
upwelling is present from December to April.
Objective: Within this seasonal upwelling area, Salinas Bay was sampled to determine whether the upwelling has
an effect on the diversity, composition, and trophic guilds of the soft-bottom benthic community.
Methods: The bay was visited during the upwelling and non-upwelling seasons of 2007-2009. A number of six to
nine grab samples were taken in each sampling event.
Results: Richness and abundance were lower in the non-upwelling season and the highest values were observed
at the end of the upwelling. The taxa composition of assemblages varied partially across the seasons, depending
on the upwelling intensity.
Conclusions: The species composition was more diverse and abundant at the end of the upwelling season than at
the start or in the non-upwelling season. Differences in infaunal assemblages during the seasonal upwelling could
be explained by the change in characteristics of the sediment-water interface, nutrients, and sediment movements
that promote the increase of planktonic productivity, and thus food availability.
Key words: diversity; benthos; sediment processes; recruitment; nutrient dynamics; mollusks; population
dynamics.
RESUMEN
Cambios en el ensamblaje bentónico de fondos blandos debido
al afloramiento estacional tropical (Bahía Salinas, Pacífico, Costa Rica)
Introducción: El afloramiento estacional es un desplazamiento de agua de mar superficial hacia la costa y su
reemplazo por agua más profunda y fría con mayores niveles de nutrientes por la influencia del viento. En la costa
norte del Pacífico de Costa Rica, el afloramiento está presente de diciembre a abril.
https://doi.org/10.15517/rev.biol.trop..v73iS1.63714
SUPPLEMENT
2Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
INTRODUCTION
In upwelling areas, the warm surface water
is pushed offshore by winds and replaced by
cool deeper water with higher nutrient levels
(Witman, 2007). Marine benthic communities
respond to these water column fluctuations
(Alongi, 1989a). This coupling between water
column processes and the benthos has been
documented by Alongi (1990), Graf (1992),
Posey et al. (1995), and Witman (2007). In this
context, input of organic matter from plankton
can result in an increase of benthic biomass, or
it could sustain the macrobenthos in posterior
oligotrophic environments (Cosentino & Gia-
cobbe, 2008; Escobar-Briones & Soto, 1997).
The upwelling process results in positi-
ve and negative effects on the marine fauna.
For example, in Peru and Africa the upwe-
lling has a positive influence on the biomass
of benthic fauna (Alongi, 1990). Conversely,
Alongi (1989b) points out that intense or cons-
tant upwelling on these shelves, and on the
California coast, can have deleterious effects by
exposing the benthos to anoxia. Additionally,
the larval recruitment of benthic taxa can be
reduced with an increase in the intensity (tem-
poral permanence) of the upwelling (Menge
et al., 1997, Menge et al., 2003), by exporting
larval stages offshore.
The intensity or temporal permanen-
ce of the upwelling causes variations in taxa
composition, as observed in rocky shore com-
munities of both temperate and tropical loca-
lities (Cortés et al., 2014; Menge et al., 1997;
Menge et al., 2003; Sibaja-Cordero & Cortés,
2008). Connolly & Roughgarden, (1999); Menge
et al., (1997) and Phillips, (2005) have docu-
mented that areas with less intense upwelling,
such as Oregon and the north of California,
exhibit increased density, biomass, and growth
of filter feeders compared to areas with stronger
upwelling, like the south of California. These
increases are attributed to the more stable and
favorable conditions for filter feeders and their
recruits in these less intense upwelling zones.
Another example is the Galapagos Islands
where both the number and the cover of rocky
subtidal species (mainly suspension feeders)
increased twofold when the upwelling events
(causing the water temperature to drop by 3 to
9 ºC in less than a day) became more frequent
and predictable from June to February (Wit-
man & Smith, 2003). Sibaja-Cordero & Cortés
(2008) report a change in the composition of
rocky shore assemblages with more macroalgae
cover during the season of upwelling in contrast
with a less diverse assemblage dominated by
barnacles in the non-upwelling season in Bahía
Salinas, Costa Rica. In the case of soft-bottom
systems, Quintana et al. (2015) noted that lower
abundance values during non-upwelling perio-
ds compared to upwelling seasons in southeast
Brazil can be the result of the decreased organic
Objetivo: Dentro de esta área de afloramiento estacional, se muestreó la Bahía de Salinas para determinar si el
afloramiento tiene un efecto sobre la diversidad, composición y gremios tróficos de la comunidad bentónica de
fondos blandos.
Métodos: La bahía fue visitada durante las temporadas de afloramiento y no afloramiento de 2007-2009. Se toma-
ron de seis a nueve muestras al azar en cada evento de muestreo.
Resultados: La riqueza y abundancia fueron menores en la temporada sin afloramiento y los valores más altos se
observaron al final del afloramiento. La composición de taxones de los ensamblajes varió parcialmente a lo largo
de las estaciones, dependiendo de la intensidad del afloramiento.
Conclusiones: La composición de especies fue más diversa y abundante al final de la temporada de afloramiento
que al inicio o en la temporada sin afloramiento. Las diferencias en los conjuntos infaunales durante el aflo-
ramiento estacional podrían explicarse por el cambio en las características de la interfaz sedimento-agua, los
nutrientes y los movimientos de sedimentos que promueven el aumento de la productividad planctónica y, por lo
tanto, la disponibilidad de alimentos.
Palabras clave: diversidad; bentos; procesos sedimentarios; reclutamiento; dinámica de nutrientes, moluscos;
dinámica poblacional.
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matter quality (detritus from phytoflagellate or
diatom blooms) on the bottom.
A seasonal upwelling system has a tempo-
ral displacement offshore of the coastal surface
seawater by the strong influence of wind. As the
wind relaxes, the coastal system changes toward
its initial condition. Seasonal upwellings in the
neotropics occur in the Gulf of Tehuantepec
(Mexico), Bay of Panama (Panama), and the
Pacific coast of south of Nicaragua to Gulf of
Papagayo, Costa Rica. During the dry season
(December to April) the Trade Winds blow
across Mesoamerica, from the Caribbean to
the Pacific, producing strong Northeasterly
winds, and resulting in a coastal upwelling of
cooler nutrient-rich waters with lowest dissol-
ved oxygen content (Alfaro & Cortés, 2012;
Chelton, 2000a, Chelton, 2000b; Legeckis, 1988;
McCreary et al., 1989).
During the upwelling season, the water
temperature in the Gulf of Papagayo dropped
by 7 °C to 9° C, while the nutrient concen-
trations rose by 3 to 15-fold. This stimulated
phytoplankton growth, resulted in a 3 to 6-fold
increase in chlorophyll concentration (Stuhl-
dreier et al., 2015). This primary production
and nutrient availability in the water column
during upwelling possibly promote the develo-
pment of diverse and abundant macrobenthic
populations in the sediments of these areas
(Alongi, 1990; Lee 1978; Menge et al., 2003).
The small bay of Bahía Salinas (North Pacific
of Costa Rica) is located in an area where the
Trade Winds blow can blow with more inten-
sity, because this zone has a low altitude of
mainland, and a marked east-west axis which
allows the winds to pass through without much
obstruction (Alfaro & Cortés, 2021).
This study examines how the benthic taxa
and feeding guilds vary in number, abundan-
ce, and composition between upwelling and
non-upwelling seasons in Bahía Salinas. It also
describes the oceanological and environmental
conditions during the study period and the
spatial variability of the benthic macrofauna
within the bay.
MATERIALS AND METHODS
The oceanological and environmental con-
ditions were measured to describe the periods
of upwelling vs no upwelling in the specific
locality of Bahía Salinas, North Pacific of Costa
Rica during December 2007 to April 2009 (Fig.
1). Data on chlorophyll (µg/L) concentration,
sea surface temperature (ºC), and wind velocity
(m/s) to characterize the bay were obtained
from the satellite data MODIS, AVHRR P5.1,
QuickCAT, respectively available in NOAA
Ocean Watch Voyager (http://www.pacioos.
hawaii.edu/voyager/oceanwatch.html). The
data are monthly averages derived from a box
between 85° 38’ 32.64” W to 86° 15’ 0.36” W
and 10° 56’ 56.76” N to 11° 9’ 2.16” N (Fig.
1). Additionally, seawater temperature at the
bottom was recorded in situ with Hobo®Temp
sensors, every 30 min at 3–6 m and 6.5–9 m
depth, within the bay and outside the bay, sta-
tions H1-H2 and H3-H4, respectively, during
the study period (Fig. 1). The mean ± standard
deviation, minimum, and maximum values
of these variables recorded were presented as
indicators of upwelling.
Four sampling visits (December 2007,
August 2008, December 2008 and April 2009)
were carried out to study the subtidal benthic
community of Bahía Salinas. The bottom of
the bay (Fig. 1) was divided into three zones:
the inner bay (3 to 18 m depth at chart datum),
middle bay (18 to 35 m depth) and outside bay
(35 to 40 m depth).
A Petite Ponar grab (sampling area: 15.2
x 15.2 cm) was used to sample the sediment
and biotic assemblages from an 11 km tran-
sect from the inner to outside bay (Fig. 1). In
December 2007 (start of the upwelling season),
nine grabs were collected, three in each zone of
the bay (Fig. 1). In August 2008 (non–upwe-
lling season), five grabs were taken, two in
the inner bay, two in the middle bay, and one
in the outside bay. In both December 2008
(start of the upwelling season) and April 2009
(end of the upwelling season), six grabs were
collected, two in each zone of the bay (Fig. 1).
The number of sampled stations vary between
4Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
dates by the presence of adverse weather or
severe oceanographic conditions. All sediment
samples were preserved with formalin diluted
to 5 % in seawater and stained with Rose Ben-
gal. The samples were sieved through a 500 μm
mesh, gently cleaned with fresh water as per
Vargas (1987). The organisms were separated
and identified to the lowest possible taxo-
nomic category. Polychaetes were identified
following Dean (1998), Dean (2001a), Dean
(2001b) and de León-González et al. (2009),
the mollusks following Keen (1971), and the
crustaceans following Fischer et al. (1995),
Hendrickx (1997), Hendrickx (1999), Rathbun
(1918), Wicksten (1983), and Williams (1986).
The identification for other groups was done
with Carlton (2007).
Total taxa and total abundance per sam-
pling date and zone of the bay were analyzed
using a chi-squared test with expected values
corrected by sampling effort (number of grab
samples) following Krebs (1999). Additionally,
mean diversity (H) using the Shannon-Wiener
function with Ln, and mean equitability (J)
were compared between dates of the bay with a
Friedman test (F). With a Kendall’s coefficient
(Wt) was determined the degree of concordan-
ce in the values of biodiversity measures across
zones of the bay (0 = no concordance to 1 = total
concordance) (Krebs, 1999; Siegel, 1956). This
statics were carried out in R. A non-metric
Multidimensional Scaling (nMDS) based in the
Euclidean distance of the abundances (transfor-
med by Ln x+1) was used to visualize the dis-
similarity between samples according with the
zones of the bay and sampling dates (Hammer
et al., 2001). Euclidean distance of transformed
data represented a gradient in a better way than
a Bray-Curtis of the abundance data (Legendre
& Gallagher, 2001). This analysis was conduc-
ted using the vegan package in R (Oksanen
et al., 2019). In the PAST software, a two-way
ANOSIM test was carried out to determine the
degree of discrimination (R value as in Clarke,
l993) between sampling date and zone of the
bay, and a SIMPER analysis was applied to the
data (Ln x+1) that provides the percentage con-
tribution of each taxa to the between-group dis-
similarity by sampling dates and zones (Clarke
& Warwick, 1994; Hammer et al., 2001).
Additional, each taxon was catalogued by
feeding guild using the information of (Fau-
chald & Jumars, 1979), Jumars et al. (2015),
and MacDonald et al. (2010), assuming that the
taxa found feed in a similar manner to species
within the same major group: suspension fee-
der (active, passive, and mixed), deposit feeder
(surface and subsurface), mobile predators,
Fig. 1. Stations for benthic grab samples during December 2007 (stations 1–9), August 2008 (stations 1, 3, 4, 6 and 8),
December 2008 and April 2009 (stations 1, 3, 4, 6, 8 and 9). Sites for Hobo®Temp sensors, labeled H1-H2 in the bay and
H3-H4 outside the bay. The satellite data of wind, seawater temperature and chlorophyll concentration comes from the box
on the figure on the right.
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scavengers, omnivores, and herbivores to des-
cribe the functional composition of the faunal
assemblages. Finally, ANOSIM and SIMPER
tests were conducted using the feeding guilds
data (Ln x+1) with Euclidean distance. The
density of individuals per m2 was calculated
from the means through a back transformation
from the estimates of the SIMPER output.
RESULTS
Oceanological and environmental condi-
tions: Wind speeds reached above 4 m/s from
November to the end of March, and presented
the minimum speeds from April to July (Fig.
2A). Sea surface temperature (SST) from sate-
llite data was lowest during the upwelling sea-
son (with minimum values of 24–25 ºC), than
during the non-upwelling season (with mini-
mum values above 28 ºC) (Fig. 2B). Mean and
minimum seawater temperature from the in-
situ sensor had lower values during upwelling
season (April: 19–21 ºC and 15–17 ºC), and
reached a higher mean during non-upwelling
season (August: 28–28.5 ºC and 25–26.2 ºC)
at the two depths and the two sites recorded
(Table 1). Water temperature was 3 to 4 ºC
cooler at 6.5–9 m than 3–6 m in both seasons
(Table 1). Increased chlorophyll concentration
was concordant with the increase in wind velo-
city and decrease of SST (Fig. 2C).
Fauna diversity and assemblages com-
position: A total of 1 969 individuals from 157
taxa were collected (Table 2). The nine grabs
from December 2007 contained 683 individuals
from 75 taxa; 136 individuals from 40 taxa
were found in August 2008 (five grabs); 252
individuals from 76 taxa in December 2008 (six
grabs); and 898 individuals from 101 taxa in
April 2009 (six grabs). Polychaetes showed the
highest percentage of total abundance and taxa,
followed by crustaceans and mollusks (Table 3).
Other relatively abundant taxa were sipuncu-
lids, nemerteans, nematodes, and echinoderms;
remaining taxa corresponded to a flatworm
(Platyhelminthes), a brachiopod, a cephalo-
chordate, and a demersal fish (Table 2, Table 3).
Differences in the number of taxa between
zones of the bay varied across sampling dates
(χ2 = 17.09, d.f. = 6, P = 0.009) (Table 4). Post-
hoc comparisons revealed that a similarly low
number of taxa were found between the zones
in August 2008 (non-upwelling season) (χ2 =
0.52, d.f. = 2, P = 0.771). In December 2007
(the start of the upwelling season), a lower taxa
number were found at mid bay (χ2 = 9.72, d.f.
= 2, P = 0.008). However, in December 2008,
there was a peak in the number of taxa in the
Table 1
Sea water temperature in the bottom by depth and date, measured at two sites in the region of Bahía Salinas, Costa Rica.
Depth (m) Mouth of the bay Out of the bay
H1 Dec 2007 Aug 2008 Dec 2008 Apr 2009 H3 Dec 2007 Aug 2008 Dec 2008 Apr 2009
3-6 Mean 23.4 28.4 26.6 19.7 Mean 23.8 28.3 24.4 21.2
Desv 1.3 0.9 0.4 0.8 Desv 1.2 0.8 1.0 3.2
Max 26.6 29.8 27.3 22.3 Max 26.8 29.4 27.4 29.0
Min 20.0 25.4 25.4 17.0 Min 21.3 25.0 22.4 16.2
Depth (m) H2 Dec 2007 Aug 2008 Dec 2008 Apr 2009 H4 Dec 2007 Aug 2008 Dec 2008 Apr 2009
6.5-9 Mean 22.98 28.28 24.07 20.41 Mean 23.6 28.5 24.0 20.8
Desv 0.38 0.96 1.01 3.05 Desv 1.2 0.7 0.7 3.1
Max 23.64 29.71 27.13 28.82 Max 26.7 30.0 26.3 28.7
Min 21.74 25.16 21.82 15.77 Min 20.9 26.2 22.1 15.4
The highest temperatures are in bold font. The minimum temperatures are underlined. H1 to H4 are the Hobo®Temp sensors.
6Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
mid bay (χ2=9.14, d.f.=2, P = 0.010). The num-
ber of taxa was higher and similar across the
bay in April 2009 (upwelling season) (χ2 = 2.87,
d.f. = 2, P = 0.238) (Table 4).
Similar to the number of taxa, the values
of the total abundance (Table 4) varied in
their distribution within the bay (factor zone)
across the sampling dates (χ2 = 145.00, d.f. = 6,
Fig. 2. A. Wind velocity, B. superficial seawater temperature, and C. Chlorophyll concentration from satellite data offshore
of Bahía Salinas, Costa Rica. Data from NOAA Ocean Watch Voyager. The gray areas represent the benthic sampling events.
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Table 2
Taxa found during the benthic grab samples by dates in Bahía Salinas, Costa Rica.
Taxonomic group Taxa Feeding
guilds
SU NU SU U
Total
Dec.
2007
Aug.
2008
Dec.
2008
Apr.
2009
Polychaeta Acrocirridae Acrocirridae indet. Ds 1 1 2
Ampharetidae Amphicteis sp. Ds 7 2 1 9 19
Melinna sp. Ds 3 15 18
Capitellidae Capitella sp. Dss 2 2
Capitellidae indet. Dss 1 1
Dasybranchus lumbricoides Dss 1 1
Decamastus nudus Dss 1 5 6
Heteromastus filiformis Dss 1 1
Mediomastus ambiseta Dss 2 1 3 6
Mediomastus californiensis Dss 4 4
Nootmastus tenuis Dss 2 2
Notomastus lineatus Dss 1 1 2
Peresiella sp. Dss 1 1
Chaetopteridae Mesochaetopterus sp. Sfa 1 1
Cirratulidae Cirratulidae indet. Ds 28 2 16 198 244
Cossuridae Cossura brunnea Dss 1 1 3 5
Dorvilleidae Dorvillea sp. Pm-Sca 1 1 5 7
Eulepethidae Grubeulepis ecuadorensis Pm 1 1
Glyceridae Glycera sp. Pm 3 5 4 12
Goniadidae Glycinde armigera Pm 2 1 1 4
Goniada sp. A Pm 3 18 21
Goniada sp. B Pm 4 4
Goniadidae indet. Pm 3 1 4
Hesionidae Gyptis sp. Pm 1 3 8 12
Hesione panamena Pm 2 2
Hesionides arenarius Pm 1 1
Lumbrineridae Lumbrineridae indet. A Pm 2 2 4
Lumbrineridae indet. B Pm 13 4 3 24 44
Magelonidae Magelona californica D-Pm 4 1 2 7
Magelona pacifica D-Pm 9 10 11 30
Maldanidae Heteroclyne cf. glabra Dm 1 1
Maldanidae indet. Dm 1 1
Maldanidae Indet. A Dm 1 1
Nepthyidae Aglaophamus sp. Pm 2 2
Aglaophamus verrilli Pm 4 12 10 4 30
Nepthys panamanensis Pm 26 4 7 12 49
Nereididae Ceratonereis singularis
(Juvenile) Om 1 1
Gymnonereis crosslandi Om 3 1 1 5
Neanthes microma Om 1 1
Nereis sp. (Juvenile) Om 2 2
Nereididae (Juvenile) Om 2 2
Nereid larvae Om 1 1 2
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Taxonomic group Taxa Feeding
guilds
SU NU SU U
Total
Dec.
2007
Aug.
2008
Dec.
2008
Apr.
2009
Onuphidae Diopatra tridentata Om 3 1 1 13 18
Kinbergonuphis microcephala Om 7 3 4 17 31
Ophelidae Armandia brevis Dss 8 1 1 25 35
Orbiniidae Scoloplos armiger Dss 1 1 1 3
Scoloplos sp. Dss 3 2 5
Owenidae Owenia fusiformis SFp-Ds 1 1
Paraonidae Acesta (Acmira) lopezi Dm 1 1 2 4
Aricidea (Acmira) catherinae Dm 25 4 15 42 86
Aricidea (Aedicira) sp. A Dm 3 2 5 10
Aricidea (Aedicira) sp. B Dm 2 2 4
Levensenia gracilis Dm 1 1
Phyllodocidae Eumida longicornuta Pm-Sca 1 1
Phyllodoce madeirensis Pm-Sca 2 7 9
Phyllodoce sp. Pm-Sca 1 1 11 13
Phyllodocidae indet. A Pm-Sca 1 1
Phyllodocidae indet. B Pm-Sca 1 1
Pilargidae Loandalia riojai Pm 1 2 4 7
Parandalia tricuspis Pm 3 4 7
Sigambra sp. Pm 1 1
Sigambra tentaculata Pm 22 22
Polynoidae Polynoidae indet. Pm 3 1 4
Sabellariidae Idanthyrsus sp. SFp-Ds 1 1
Sabellidae Sabellidae indet. SFp 28 4 6 103 141
Sigalionidae Sthenelais fusca Pm 2 2 2 6
Spionidae Apoprionospio pygmaea SFp-Ds 10 1 2 13
Dipolydora socialis SFp-Ds 1 1
Paraprionospio pinnata SFp-Ds 167 1 17 25 210
Prionospio (Minuspio)
multibranchiata Ds 28 15 18 61
Prionospio (Prionospio)
ehlersi Ds 1 1
Prionospio delta Ds 5 5
Prionospio sp. A Ds 3 3
Scolelepis (Scolelepis)
squamata SFp 1 26 27
Spiophanes duplex SFp-Ds 19 1 4 3 27
Spiophanes sp. A SFp-Ds 1 1 2
Syllidae Brania sp. Om 1 1
Exogone breviantenata Om 2 1 3
Exogone dispar Om 2 1 3 6
Terebellidae Terebellidae indet. Ds 2 1 3
Trichobranchidae Terebellides reishi Dss 21238
Oligochaeta Oligochaeta indet. Dss 5 5
Sipuncula Aspidosiphonidae Aspidosiphon sp. Dm 1 1 2 4
Aspidosiphon sp. A Dm 1 1 2
Phascolosomatidae Apionsoma sp. Dm 5 28 14 20 67
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Taxonomic group Taxa Feeding
guilds
SU NU SU U
Total
Dec.
2007
Aug.
2008
Dec.
2008
Apr.
2009
Mollusca /
Class Gastropoda
Bullidae Bullidae indet. H 3 3
Caecidae Caecidae indet. Pm 1 1
Naticidae Natica sp. Pm 1 1 2
Sinum noyesii Pm 2 2
Naticidae (Juvenile) Om 1 1
Bivalvia indet. SFa 1 2 3
Mollusca /
Class Bivalvia
Corbulidae Corbullidae indet. SFa 2 2
Donacidae Donacidae indet. SFa 1 2 3
Mytilidae Mytilidae indet. (Juvenile) SFa 1 1
Nuculidae Nucula (Saccella) elenensis SFa 1 1
Veneridae Pitar helenae SFa 1 1
Veneridae indet. (Juvenile) SFa 1 12 13
Tellinidae Tellina (Eurytellina) eburnea
eburnea SFa 3 1 4
Tellinidae indet. (Juvenile) SFa 4 1 30 35
Crustacea / Class
Malacostraca / O.
Decapoda /I.O. Brachyura
Raninidae Raninoides benedicti
Om 4 2 1 7
Pseudorhombilidae Malacoplax californiensis Pm 1 6 3 10
Parthenopidae Mesorhoea bellii Om 1 1
Pinnotheridae Pinnotheridae indet. Om 1 1
Parthenopidae Upogebia jonesi Om 1 1
Thalassinidea Thalassinidea indet. Om 3 3
Crustacea /
Class Malacostraca / O.
Decapoda /
I.O. Caridea
Caridea indet. A
Om 1 1
Caridea indet. B Om 1 1
Caridea indet. C Om 1 1
Caridea indet. D Om 1 1
Processidae Processa peruviana Om 2 2
Pasiphaeidae Leptochela gracilis Om 1 1
Penaeidae Penaeidae indet. Om 3 3
Alpheidae Alpheus sp. Pm 2 1 1 4
Automate dolichognatha Pm 1 1
Zoea larvae Om 1 1
Crustacea / Class
Malacostraca / O.
Amphipoda
Amphipoda indet. A
Om 174 36 15 23 248
Amphipoda indet. B Om 1 2 3
Amphipoda indet. C Om 1 2 7 10
Amphipoda indet. D Om 1 1 2
Amphipoda indet. E Om 1 6 7
Amphipoda indet. F Om 1 10 11
Amphipoda indet. G Om 1 2 3
10 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
Taxonomic group Taxa Feeding
guilds
SU NU SU U
Total
Dec.
2007
Aug.
2008
Dec.
2008
Apr.
2009
Amphipoda indet. H Om 1 2 3
Amphipoda indet. I Om 1 1
Amphipoda indet. J Om 10 10
Amphipoda indet. K Om 1 1
Amphipoda indet. L Om 1 1
Amphipoda indet. M Om 11 11
Caprellidae indet. H 1 7 8
Crustacea / Class
Malacostraca / O.
Cumacea
Cumacea indet. A
Om 1 1 2 4
Cumacea indet. B Om 1 1
Cumacea indet. C Om 1 1
Cumacea indet. D Om 2 2 4
Crustacea / Class
Malacostraca / O. Isopoda
Gnathiidae Gnathia sp. Pm 1 1
Isopoda indet. A Om 1 1
Isopoda indet. B Om 1 1
Isopoda indet. C Om 3 3
Isopoda indet. D Om 2 2
Crustacea / Class
Malacostraca / O.
Leptostraca
Nebaliidae Nebalia sp.
Pm 1 1 2
Crustacea / Class
Copepoda / O.
Harpacticoida
Harpacticoida indet. A
Om 8 1 9
Harpacticoida indet. B Om 5 2 7
Harpacticoida indet. C Om 1 1
Crustacea / Class
Ostracoda
Ostracoda indet. A Om 2 2
Ostracoda indet. B Om 1 1
Ostracoda indet. C Om 1 1
Ostracoda indet. D Om 6 6
Ostracoda indet. E Om 1 1
Ostracoda indet. F Om 1 1
Nemertea Nemertea indet. Pm 6 1 6 19 32
Platyhelminthes / Class
Rabditophora / O.
Tricladida
Tricladida indet.
Pm 1 1
Brachiopoda / Class
Inarticulata
Lingulidae Glottidia albida Sfa 1 2 3
Nematoda Nematoda indet. Om 13 13
Echinodermata / Class
Asteroidea
Asteroidea indet. Pm 3 1 4
Echinodermata / Class
Holothuroidea
Holuthuroidea indet. Dss 1 1
Echinodermata / Class
Ophiuroidea
Ophiuroidea Ophiuroidea indet. Sfa 1 6 7
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Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
Taxonomic group Taxa Feeding
guilds
SU NU SU U
Total
Dec.
2007
Aug.
2008
Dec.
2008
Apr.
2009
Chordata / Subphyllum
Cephalochordata / Class
Leptocardii
Branchiostomatidae Branchiostoma californiense
SFa 2 2
Chordata / Subphylum
Vertebrata / Class Teleostei
Ophichthidae Ophichthidae indet. Pm 1 1
SU: Start upwelling season, NU: non–upwelling season, and U: upwelling season. Feeding guilds, D: Deposit feeder, s: surface,
ss: subsurface, m: mixed; SF: Suspension feeder, a: active, p: passive; Pm: Predator mobile; Sca: Scavenger; Om: Omnivore,
H: Herbivore.
Table 3
Percentage of taxa and total abundance of each faunal group by dates. Bahía Salinas, Costa Rica.
Taxa %
Dec–07 Aug–08 Dec–08 Apr–09
Annelida 69 65 53 64
Crustacea 19 15 39 23
Mollusca 8 10 4 8
Others 4 10 4 5
Abundance Dec–07 Aug–08 Dec–08 Apr–09
Annelida 67 60 67 80
Crustacea 29 34 27 11
Mollusca 2 4 1 6
Others 3 3 4 3
The total number of taxa and individuals was lower during the non-upwelling season, at the start of the upwelling season,
these values increased. By the end of the upwelling season, both values were even higher (taxa: χ2 = 29.24, d.f. = 3, P < 0.001;
individuals: χ2 = 678.75, d.f. = 3, P < 0.001, Table 4).
P < 0.001). Post-hoc comparisons revealed that
the middle of the bay showed the lowest abun-
dance in December 2007 (χ2 = 254.46, d.f. = 2, P
< 0.001), while higher abundance was observed
in the mid bay during August and December
2008 (P < 0.001, d.f. = 2, with χ2 = 17.71 and χ2
= 33.17, respectively). Finally, the abundance
values were high at mid and outer bay areas
during April 2009 (χ2 = 91.25, d.f. = 2, P <
0.001) (Table 4).
A temporal effect was found for the Shan-
non-Wiener diversity index (Friedman test, χ2
= 8.20, d.f. = 3, P = 0.042), with the highest
value during upwelling season (April 2009) and
the lowest value during non-upwelling season
(Table 4). This pattern was concordant in high
degree across the zones of the bay (Kendall’s
concordance: Wt = 0.91). However, a non-
temporal trend was found for the equitability
(Friedman, χ2 = 1.8, d.f. = 3, P = 0.615) by the
low concordance of values between the zones
of the bay (Kendall’s concordance: Wt = 0.20)
(Table 4). The trend consisted in a decrease of
equitability from inner to outside bay (Table 4).
The NMDS (Fig. 3) showed that the bio-
logical assemblage composition of samples
collected in August was more similar to each
other than to samples collected during other
periods at the same location. In contrast, high
variation was found in the samples collected in
April 2009. Dimension 1 of the NMDS revealed
the pattern of change in the community from
non-upwelling to upwelling season, where the
assemblages presented a mid-degree of discri-
mination between sampling dates (ANOSIM, R
= 0.46, P = 0.0004). No difference in the assem-
blages was found between the start of upwelling
season (December) and non-upwelling season
12 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
Table 4
Biodiversity parameters by date and zone of the bay of the benthic macrofauna of Bahía Salinas, Costa Rica.
Species
Zone December 2007 August 2008 December 2008 April 2009 Total number of species
Inner bay 36 16 29 49 88
Middle bay 26 19 52 67 103
Outer bay 53 15 30 56 96
Total number of species 75 40 76 101 157
Abundance
Zone December 2007 August 2008 December 2008 April 2009 Total abundance
Inner bay 137 26 52 166 381
Middle bay 122 66 125 348 661
Outer bay 424 44 75 384 927
Total abundance 683 136 252 898 1969
Shannon-Wiener
Zone December 2007 August 2008 December 2008 April 2009 Mean Diversity
Inner bay 2.04 1.75 2.19 2.92 2.20
Middle bay 2.03 1.88 3.16 3.01 2.46
Outer bay 2.08 1.77 2.53 2.77 2.33
Mean Diversity 2.05 1.81 2.63 2.90 2.33
Equitability
Zone December 2007 August 2008 December 2008 April 2009 Mean equitability
Inner bay 0.87 0.84 0.83 0.87 0.86
Middle bay 0.84 0.73 0.91 0.80 0.82
Outer bay 0.62 0.66 0.91 0.76 0.73
Mean equitability 0.78 0.76 0.89 0.81 0.81
The highest values are in bold font and the lowest values are underlined.
Fig. 3. MDS to show the similarity between sampling dates and zones of the bay based on their benthic macrofauna. Bahía
Salinas, Costa Rica. The ellipses are the convex hull that contains all the samples in the group.
13
Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
indet. A and three polychaete taxa had high-
density values outside of the bay. Additionally,
the spionid Prionospio (Minuspio) multibran-
chiata had a peak of abundance at mid bay, and
P. pinnata also had high abundance at the inner
section (Table 6). In August 2008, a sipunculan
worm and the onuphid polychaete Kinbergonu-
phis microcephala presented highest densities
at the outside bay. An amphipod and a sabe-
llid polychaete had their highest abundance at
mid bay, and the decapod crustacean Malaco-
plax californiensis showed high densities at the
inner bay (Table 6). Samples from December
2007 and December 2008 recovered the same
taxa but presented higher densities in different
zones of the bay (Table 6). For example, the
polychete Aricidea (A.) catherinae and the afo-
rementioned amphipod changed the dominan-
ce from outside to mid bay (Table 6).
Finally, in April 2009 the five taxa that
contributed the most to the change in the
bay were completely different from previous
sampling dates, and the polychaetes presented
higher densities outside of the bay (Table 6).
(August) (ANOSIM, P > 0.05), but there was
degree of discrimination of 0.50–0.59 between
the assemblage in the start of upwelling season
(December) with the assemblage at the end of
the upwelling season (April). Similar situation
occurs between assemblages in the non-upwe-
lling and upwelling seasons with a degree of
discrimination 0.48 (ANOSIM, P ≤ 0.01).
The taxa that changed the most between
sampling dates corresponded to two polychae-
tes: Cirratulidae indet. that had a peak at the
upwelling season (April 2009) and the spionid,
Paraprionospio pinnata with a peak in Decem-
ber 2007 (Table 5). Both taxa presented their
lowest density in August 2008 (non-upwelling
season) (Table 5). Additionally, the amphi-
pod indet. A presented low-density values in
December 2008, and the polychaete, Aglaopha-
mus verrilli, was more abundant during the
non-upwelling season (Table 5).
The taxa that mainly contributed to the
spatial change in composition of the assembla-
ges between the zones of the bay are presented
in Table 6. In December 2007, the amphipod
Table 5
Results of the SIMPER analysis, and individuals per m2 per sampling date in Bahía Salinas, Costa Rica.
Taxa Feeding
guild
Overall average
dissimilarity Contribution
%
Cumulative
Contribution %
Dec.
2007
Aug.
2008
Dec.
2008
Apr.
2009
51.37
Cirratulidae indet. Ds 4.188 8.153 8.153 83 14 73 1062
Paraprinospio pinnata SFp-Ds 3.445 6.707 14.86 402 6 62 147
Amphipoda indet. A Om 2.851 5.55 20.41 290 134 72 117
Sabellidae indet. SFp 2.815 5.48 25.89 73 22 30 280
Aricidea (Acmira) catherinae Dm 1.885 3.67 29.56 71 28 44 235
Apionsoma sp. Dm 1.596 3.106 32.67 20 76 71 87
Prionospio (Minuspio) multibranchiata SFp-Ds 1.572 3.06 35.73 71 0 58 100
Tellinidae indet. (Juvenile) SFa 1.502 2.925 38.65 8 6 0 194
Scolelepis (Scolelepis) squamata SFp 1.117 2.175 40.83 3 0 0 91
Nepthys panamanensis Pm 1.068 2.078 42.9 93 22 24 74
Lumbrineridae indet. B Pm 1.061 2.065 44.97 38 32 18 106
Sigambra tentaculata Pm 1.06 2.064 47.03 0 0 0 95
Armandia brevis Dss 1.045 2.034 49.07 29 6 5 61
Kinbergonuphis microcephala Om 1.037 2.018 51.09 20 14 18 83
The composition of the benthic fauna showed a marked change from inner to outside of the bay (ANOSIM, R= 0.60, P
= 0.0001). In the NMDS (Fig. 3) this trend was observed within each sampling date, most notably in April 2009 (average
dissimilarity: ad = 69.75, Table 5), followed by December 2007 (ad = 38.85, Table 5) and 2008 (ad = 35.04, Table 6), with the
lowest differentiation observed in August 2008 (ad = 21.34, Table 6; Fig. 3).
14 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
Table 6
Results of the SIMPER analysis, and individuals per m2 by zone of the bay. Bahía Salinas, Costa Rica.
Dec 2007 Average dissimilarity
38.85 %Cumulative % Inner Middle Outer
Amphipoda indet. A 5.26 13.54 13.54 40 290 1307
Paraprinospio pinnata 3.90 10.03 23.56 229 184 1362
Aricidea (Acmira) catherinae 2.12 5.46 29.02 11 35 300
Sabellidae indet. 1.84 4.73 33.75 35 53 165
Prionospio (Minuspio) multibranchiata 1.82 4.67 38.42 70 151 25
Aug 2008 Average dissimilarity
21.34 %Cumulative % Inner Middle Outer
Apiosoma sp. 4.48 21.00 21 0 63 1084
Amphipoda indet. A 4.44 20.81 41.81 18 690 43
Malacoplax californiensis 1.42 6.65 48.46 71 0 0
Kinbergonuphis microcephala 0.96 4.50 52.97 0 0 130
Sabellidae indet. 0.90 4.22 57.19 0 79 0
Dec 2008 Average dissimilarity
35.04 %Cumulative % Inner Middle Outer
Aricidea (Acmira) catherinae 2.99 8.52 8.523 0 307 0
Prionospio (Minuspio) multibranchiata 2.20 6.27 14.79 0 43 229
Paraprinospio pinnata 1.91 5.44 20.23 93 71 32
Amphipoda indet. A 1.47 4.21 24.44 18 246 43
Cirratulidae indet. 1.35 3.85 28.29 63 79 79
Apr 2009 Average dissimilarity
69.75 %Cumulative % Inner Middle Outer
Sabellidae indet. 5.88 8.43 8.429 63 141 1690
Goniada sp. A 3.31 4.74 13.17 0 0 332
Armandia brevis 3.22 4.62 17.79 0 32 307
Scolelepis (Scolelepis) squamata 2.42 3.48 21.27 18 141 169
Sigambra tentaculata 2.29 3.29 24.55 32 43 363
Additionally, sabellid worms were the domi-
nant group outside of the bay in that month
(Table 6).
The ANOSIM test indicated the change
of the feeding guilds composition by sampling
dates (R = 0.47, P = 0.001) and zones of the bay
(R = 0.34, P = 0.007). The SIMPER test by sam-
pling date indicated that surface deposit feeders,
passive suspension feeders, omnivores, and
active suspension feeders were the main feeding
guilds to explain the changes in the assemblages
between sampling dates (Table 7). These groups
presented low densities and taxa values during
the non-upwelling season, the number of taxa
increased at the start of the upwelling season,
and the groups reached higher densities during
the upwelling season. Among the groups that
reached higher densities during the upwelling
season, the highest corresponded mainly to
the surface deposit feeders and the active sus-
pension feeders. This pattern was present in
the rest of the feeding guilds (Table 7). Finally,
the assemblage was dominated by omnivores,
mobile predators, and deposit feeders with
mixed strategies during the non-upwelling sea-
son, but their densities were lower than during
the upwelling season.
The variation of the assemblages between
zones of the bay was marked by the surface
deposit feeders, passive suspension feeders,
omnivores, and mobile predators (Table 7).
The general trend was that the density increa-
sed from inner to outside bay in the feeding
guilds with contribution higher than 8 %. In
15
Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
the rest, the trend was a peak of density at mid
bay (Table 7). The number of taxa by feeding
guild was less variable between zones of the bay
(Table 7).
DISCUSSION
In the present study, the macrofauna had
a low diversity and abundance in the non-
upwelling season, which increased to a peak
with the development of the upwelling season.
Lee (1978) also found a change in the subtidal
benthos of Panama Bay, concordant with the
upwelling seasonality. The opportunist taxa
such as spionids and cirratulids polychaetes
of the benthos of Bahía Salinas can better uti-
lize the input of food from the high plankton
production during the upwelling months, as
pointed out by Alongi (1989b) and Alongi
(1990) in other localities. In the present study,
there was a degree of discrimination (R) of 0.36
in the composition of taxa between December
2007 and December 2008, but the degree of
discrimination had lower magnitude (R = 0.17)
in the feeding guilds composition between
these years.
During the start of the upwelling sea-
son (December 2007 and 2008), taxa such as
Table 7
Number of taxa (S) and density (D): ind/m2, and % of the community by feeding guilds of the Bahía Salinas.
Feeding
guild
SIMPER Species Density (ind/m2)
Av. Dissim.
19.98 Contrib. % Cumulative % Dec 2007 Aug 2008 Dec 2008 Apr 2009 Dec 2007 Aug 2008 Dec 2008 Apr 2009
Ds 4.1 20.5 20.5 8 2 5 6 213 22 169 1404
SFp 3.1 15.6 36.1 7 2 3 5 82 22 30 355
Om 2.0 10.2 46.3 8 5 6 6 539 277 332 800
SFa 1.8 9.2 55.6 6 4 6 6 42 32 68 468
Dm 1.8 9.0 64.6 8 4 5 6 122 196 196 463
Pm 1.7 8.6 73.2 9 5 6 6 705 175 495 967
Dss 1.6 8.0 81.2 6 4 5 5 55 53 54 267
SFp-Ds 1.2 6.1 87.3 6 2 4 3 71 14 61 28
D-Pm 1.1 5.4 92.6 6 4 3 5 59 32 22 112
Pm-Sca 1.0 4.8 97.5 2 1 1 5 7 6 5 108
H 0.5 2.6 100.0 0 0 1 4 0 0 5 53
Feeding
guild
SIMPER Species Density (ind/m2)
Av. Dissim.
40.16 Contrib. % Cumulative % Inner Middle Outer Total of
species Inner Middle Outer Mean
density
Ds 3.6 18.8 18.8 6 7 8 9 112 252 474 279
SFp 3.1 16.1 34.9 4 7 6 2 24 100 187 104
Om 2.2 11.7 46.6 8 9 8 56 238 690 620 516
Pm 1.8 9.2 55.8 9 9 8 32 367 474 967 603
Dm 1.7 9.1 64.9 7 8 8 11 129 206 340 225
Dss 1.6 8.2 73.2 5 7 8 17 41 80 167 96
SFa 1.5 7.8 81.0 8 7 7 13 99 65 114 93
SFp-Ds 1.2 6.5 87.5 2 7 6 7 23 62 55 47
D-Pm 1.1 5.8 93.3 4 8 6 2 20 78 74 57
Pm-Sca 0.8 4.3 97.7 2 4 3 6 10 24 32 22
H 0.4 2.3 100.0 1 3 1 2 3 22 6 10
Av. Dissim. = Avarage dissimilarity. Feeding guilds, D: Deposit feeder, s: surface, ss: subsurface, m: mixed; SF: Suspension
feeder, a: active, p: passive; Pm: Predator mobile; Sca: Scavenger; Om: Omnivore, H: Herbivore.
16 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
Cirratulidae, Paraprinospio pinnata, Sabellidae,
and Amphipoda presented considerable popu-
lations in the benthos. At the end of the upwe-
lling season (April 2009), the high abundance
of Cirratulidae, Sabellidae, Aricidea, and Telli-
nidae. This trend highlights the impact of sea-
sonal nutrient influx in both the water and the
sediment surface, similar to what occurs during
the seasonal upwelling in Las Perlas, Panama
Bay, which features comparable assemblage
components (Mair et al., 2009). In the case of
Kinbergonuphis possiby utilizing the abundan-
ce of phyto and zooplankton preys during this
period (Checon et al., 2017; Jumars et al., 2015).
In contrast, the non-upwelling season (August
2008) showed a decline in these groups, with a
shift towards certain taxa such as Amphipoda,
Apionsoma, Prionospio, Aricidea and Lumbri-
neridae that persisted, forming a resilient core
that adapts to food availability in the sediment,
ensuring the continuity of the assemblage even
in less favorable conditions as in other tropical
soft bottom assemblages (Tavakoly-Sany et al.,
2018). Pacheco et al. (2010) suggested that
diverse pathways in the succession process can
produce different end points of the communi-
ties in subtidal benthos within the same locality.
In the present study, year to year, the decline of
certain populations during the non-upwelling
season results in variable group of survival taxa.
This condition allows other taxa to dominate or
to be recruited to fill the empty niches resulted
in a major taxonomic dissimilarity than the
feeding guild dissimilarity.
During the upwelling season, the commu-
nity was composed mainly of surface deposit
feeders (Cirratulidae and Paraonidae worms)
and active suspension feeders (tellinid and
venerid clams), both in high densities, but both
groups decreased during the non-upwelling sea-
son. Guzmán-Alvis et al. (2006) indicated that
in Bahía Portete in the Colombian Caribbean
deposit feeders dominated the fauna during
the upwelling season because of the increase in
available food on the seabed. This is the case
of a Cirratulidae indet. and Aricidea (Acmira)
catherinae (surface or mixed deposit feeders),
which were within the main contributors to
the total abundance during upwelling season,
but had low abundance during the non-upwe-
lling season. Similarly, surface deposit feeders
accounted for less than a third of the number
of polychaete taxa during the non-upwelling
season in the Gulf of Panama (Mair et al.,
2009). Another opportunist group that decrea-
sed drastically during the non-upwelling season
were the passive suspension feeders, for exam-
ple the tube worms (Sabellidae). Lee (1978) also
indicated a rapid decrease in benthic biomass
of opportunist taxa when primary production
dropped during the reduction of the winds,
following the upwelling season in Panama Bay.
Similar to the present study, Quintana et al.,
(2015) found that high abundance of macrofau-
na is the result of the increase in wind velocity
and phytoflagellate blooms in a coastal upwe-
lling system in SE Brazil. It is possible that the
macrofauna responds positively to the organic
matter from the phytoplankton blooms that
occur during the upwelling events in this region
of Costa Rica (Morales-Ramírez et al., 2016).
Deposit feeders with a mixed strategy
(surface and subsurface) such as sipunculans,
mobile omnivores (mainly amphipods), and
predators (the polychaete Aglaophamus verrilli
and the crustancean Malacoplax californiensis)
were the remaining fauna during the non-
upwelling season. Within the deposit feeders, a
few taxa of Ampharetidae, Cirratulidae, Cossu-
ridae, Maldanidae, Spionidae, Paraonidae and
Capitellidae persisted in low numbers during
the non-upwelling season, because these taxa
were able to compete during the period of low
food supply. One example was the opportu-
nist capitellid Mediomastus ambiseta, which
was found in the non-upwelling season, whilst
other capitellids were not recorded. In con-
trast, other capitellids have not been recorded
during this season because these are opportu-
nist taxa (Fauchald & Jumars, 1979), but this
pattern could be due to numerous factors,
such as nutrient availability, water temperature
changes, and variations in granulometry, or
biological interactions whether these factors
are directly related to upwelling phenomena
or not (Alongi, 1990). Graf (1982) pointed out
17
Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
that some infaunal organisms bury for food
into the sediment, thus avoiding competition
with surface deposit feeders. That food could
be used later during a period of scarcity. Addi-
tionally, populations that persist through the
year (i.e. spionid worms and tellinid bivalves)
would have the capacity to use different food
sources by switching between surface detritus
or suspension feeding when necessary (Cosen-
tino, & Giacobbe, 2008). This could explain in
part the coexistence of some subsurface deposit
and filter feeders after the upwelling events in
the present study.
Finally, the number of taxa varied among
zones of the bay in December, but the number
of taxa was similar across the bay during August
(non-upwelling season) and April (upwelling
season). The abundance was low in August and
higher during April. The harsh benthic condi-
tions in Bahía Salinas at the beginning of the
upwelling season (December), including lower
bottom water temperature and lower concen-
tration of dissolved oxygen are similar to those
in the Culebra Bay, Gulf of Papagayo (Rixen et
al., 2012). These conditions could explain the
pattern of spatial variation, as found in other
benthic systems (Alongi, 1990; Gray & Elliot,
2009; Mair et al., 2009). Additionally, dry and
rainy seasons can influence tropical benthic
systems abundance and distribution as in Golfo
de Nicoya, Costa Rica (Maurer & Vargas, 1984;
Maurer et al., 1988). The abundance and diver-
sity index values were more spatially variable,
but results show low equitability in the outside
bay. This is the result of several taxa that chan-
ged their distribution within the bay through
the study period due to differences in the envi-
ronmental conditions. For example, changes
in the dynamic distribution of sediments (data
not available), food availability (low during the
non-upwelling season, based on chlorophyll
concentration), and depth promote the settling,
growth, or prevalence of the different benthic
populations (Little, 2000). In this way the spa-
tial variability of the assemblages was higher
during the upwelling season, and the popula-
tions from the outside bay reached maximum
density values. Moreover, the spatial pattern
of the feeding guilds within the bay was more
stable that the taxonomic composition of the
assemblage, with an increase of the main fee-
ding guilds from inner to outside bay.
During the upwelling season, the abun-
dance and diversity of benthic communities
increased in comparison with the non-upwe-
lling season. The variation in the composition
of assemblages and diversity occurs in all the
zones of this bay, although the outside bay
presents lower values of equitability. During
the upwelling season, the community was com-
posed mainly of surface deposit feeders and
active suspension feeders. These groups possi-
bly utilize the organic matter that sinks to the
bottom, produced by planktonic organisms.
At the non-upwelling season, the community
was dominated by deposit feeders with a mixed
strategy (surface and subsurface), mobile omni-
vores, and predators.
During the upwelling season in Bahía Sali-
nas, species richness and abundance of benthic
fauna peak, likely due to high plankton pro-
ductivity. In contrast, the non-upwelling season
shows a decline in these parameters, shifting
from surface deposit and suspension feeders
to mixed strategies and omnivore feeders.
These findings highlight the dynamic nature
of benthic communities, adapting their traits to
environmental variations in tropical seasonal
upwelling areas.
Ethical statement: the authors declare
that they all agree with this publication and
made significant contributions; that there is
no conflict of interest of any kind; and that we
followed all pertinent ethical and legal proce-
dures and requirements. All financial sources
are fully and clearly stated in the acknowled-
gments section. A signed document has been
filed in the journal archives.
ACKNOWLEDGMENTS
Davis Morera and Eleazar Ruiz helped
in the field work. We thank Damien Waits
for improving the English of the manuscript.
This study is part of the Project 808-A5-037,
18 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73(S1): e63714, enero-diciembre 2025 (Publicado Mar. 03, 2025)
“Comunidades bentónicas y caracterización
física y química de Bahía Salinas” funded by
the Vicerrectoría de Investigación, Universidad
de Costa Rica.
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