biomass and secondary production of juvenile stages of acartia (copepoda: calanoida) populations...

BIOMASS AND SECONDARY PRODUCTION OF JUVENILE STAGES OF ACARTIA (COPEPODA: CALANOIDA) POPULATIONS FROM A SOUTHERN EUROPEAN ESTUARY (CANAL DE MIRA – RIA DE

AVEIRO, PORTUGAL

Sérgio Miguel Leandro ([email protected]) Marine Resources Research Group, School of Tourism and Mari:me Technology, Polytechnic Ins:tute of Leiria, Campus 4, 2520-‐641 Peniche, Portugal

Keywords: Acar:a tonsa; A.clausi; biomass; secondary producQon rate; Canal de Mira (Ria de Aveiro – Portugal)

Sérgio Miguel Leandro1*, Peter Tiselius2, Sónia Cotrim Marques3, Francisco Avelelas1, Pedro Sá1, Henrique Queiroga4 1 GIRM –Marine Resources Research Group, School of Tourism and Mari:me Technology, Polytechnic Ins:tute of Leiria, Campus 4, 2520-‐641 Peniche, Portugal

2 Department of Biological and Environmental Sciences, University of Gothenburg, Kris:neberg 566 SE-‐451 78 Fiskebäckskil, Sweden 3CEF -‐ Centre for Func:onal Ecology, Department of Life Sciences, University of Coimbra, PO Box 3046, 3001-‐401 Coimbra, Portugal

4 CESAM and Department of Biology, University of Aveiro, Campus Unversitário de San:ago, 3810-‐193 Aveiro, Portugal

Outline: 1. Overview 2. What we have done 3. Results 4. Discussion 5. Take home message

InternaQonal Conference on Challenges in AquaQc Sciences March 15-‐21 (2013) – Keelung Taiwan

Leandro et al (2013) [email protected]

ü  Zooplankton is a group of organisms extremely important on the transfer of maeer and energy in marine ecosystem.

ü  Among zooplankton, copepods are the most abundant organisms comprising as much as 80% of its total biomass (Kiorboe 1998).

ü  I n No r t h A t l a nQc e s t u a r i n e ecosystems, species of Acar:a genus frequently dominates the pelagic environment (Durbin & Durbin 1981, Lawrence et al. 2004, Marques et al. 2006) and may be considered a key species in the carbon flux.

1. Overview 2. What we have done 3. Results 4. Discussion 5. Take home message


Other microalgae


ü  The impact of a given species on the carbon flux and on higher trophic levels can be assessed by the calculaQon of its secondary producQon rate.

ü  Zooplanktonic producQon can be measured by: ü  the esQmate of growth and mortality in

cohorts over consecuQve sampling intervals (Parslow & Sonntag, 1979) (not reasonable to perform);

ü  the esQmate of growth rates, as weight-‐specific egg producQon or somaQc growth;

ü  SomaQc growth is frequently measured as juvenile grow, nauplii and copepodites.

ü  Hirst & Bunker 2003, revealed that juvenile copepods in the field grow at rates close to maximum laboratory rates determined at food saturated condiQons.

Uye 1988

Hirst AG, Bunker AJ (2003) Growth of marine planktonic copepods: Global rates and paeerns in relaQon to chlorophyll a, temperature, and body weight. Limnology and Oceanography 48:1988-‐2010




ü  Although, the growth models should be species-‐specific and not general growth equaQons because different copepod species shows different generaQon Qmes (Leandro et al 2006a).

ü  AddiQonally, the specific growth model should be defined for a parQcular copepod populaQon since allopatric populaQons could have different responses (Leandro et al 2006b).

ü  In previous studies (Leandro et al 2006 a, b) addressed the temperature-‐dependent growth rate of Acar:a and defined site-‐ and species-‐specific temperature-‐dependent growth models.

Leandro SM, Queiroga H, Rodriguez L, Tiselius P (2006b). Temperature dependent development and somaQc growth in two allopatric populaQons of AcarQa clausi (Copepoda: Calanoida). Marine Ecology Progress Series 322: 189-‐197 (2.315), doi: 10.3354/meps322189

Leandro SM, Tiselius P, Queiroga H (2006a) Growth and development of nauplii and copepodites of the estuarine copepod Acar:a tonsa from southern Europe (Ria de Aveiro, Portugal) under saturaQng food condiQons. Marine Biology 150: 121-‐129 (1.754), doi: 10.1007/s00227-‐006-‐0336-‐y




•  Based on that evidence, realisQc esQmates of juvenile producQon can be easily determined by:

•  combining in situ data (copepod biomass and water temperature)

•  with temperature-‐dependent growth models.

In the present study we aeempt to: (1)  describe seasonal biomass paeerns of

A.tonsa and A.clausi along a salinity gradient (Canal de Mira – Ria de Aveiro, Portugal)

(2)  esQmate secondary producQon rates of non-‐adult stages.

Fig. 1 Regression between weight-‐specific growth rate (g, day−1) and temperature (°C) for nauplii (filled symbols and con:nuous line) and copepodites (open symbols and dashed line) of Acar:a tonsa from Ria de Aveiro (Portugal) (Leandro et al 2006)

Fig. 2 Acar:a clausi -‐ Non-‐linear regression of the weight-‐specific growth rate (g, d–1) on temperature (T, °C) for nauplii and copepodites of both populaQons. The relaQonship proposed by Huntley & Lopez (1992) is indicated by the dashed line (Leandro et al 2006b)




Study area •  Canal de Mira, a sub-‐estuarine system of Ria de

Aveiro -‐ Portugal (laQtude 40º 38’ N, N, longitude 8º 44’W).

•  Tides – semidiurnal, average range of 2.1 m

•  Average depth is about 1 m

•  No thermal or salinity straQficaQon occurs, except during high peaks of freshwater discharge (mainly from rainfall and runoff from the margins)

•  Based on the abundance and distribuQon paeerns of Acar:a populaQons, Canal de Mira was divided into three disQnct zones: Zone 1 (lower estuary), Zone 2 (middle estuary) and Zone 3 (upper estuary (Leandro et al., 2013).

Fig. 3 LocaQon of Ria de Aveiro coastal lagoon (A), Canal de Mira (B), sampling sites (C) and the 3 zones previously defined by Leandro et al (2013).

Leandro SM, Tiselius P, Queiroga H (2013) SpaQal and temporal scales of environmental forcing of Acar:a populaQons (Copepoda: Calanoida) in the Canal de Mira (Ria de Aveiro, Portugal). ICES Journal of Marine Science DOI: 10.1093/icesjms/fst008




Sampling

•  Zooplankton and environmental data (salinity, temperature, chlorophyll a and SPM ) were collected at 6 fixed locaQons

•  Sampling performed between August 2000 and June 2002

•  Copepods collected by towing a 125 µm Bongo net

•  Species idenQficaQon (A.tonsa, A.clausi) and quanQficaQon of the different developmental stages, nauplii (NI to NVI), copepodites (CI to CV) and adults (males and females).

Copepod biomass

•  DW corrected for weight lost during preservaQon by a factor of 1.3 (corresponding to a loss of 30%) and converted to carbon weight (µg C) assuming this to be 40 % of DW (Omori & Ikeda 1984, Båmstedt 1986).

Fig. 4 LocaQon of Ria de Aveiro coastal lagoon (A), Canal de Mira (B), sampling sites (C)




Copepod secondary produc@on •  Daily secondary producQon rate was esQmated by the

product of biomass and the growth rate: P = B x g

where P is the daily secondary producQon (mg C m-‐3 d-‐1), B is the biomass (mg C m-‐3) and g is growth rate (d-‐1)

•  Nauplii and copepodites growth rates were taken

from specific temperature-‐dependent growth models previously defined (Table 1)

•  Mean biomass and mean daily secondary producQon

rate were calculated for each zone and month. •  In order to obtain an esQmate of biomass and

producQon for Canal de Mira (Ria de Aveiro – Portugal), the water volume for each zone and for the whole estuarine ecossysytem was taken into account (Table 2).

Species Nauplii Copepodites Reference

A.tonsa g = 0.0517 e (0.130 x T) g = 0.0364 e (0.114 x T) Leandro et al. 2006a

A.clausi g = 0.0914 e (0.0701 x T) g = 0.0591 e (0.0775 x T) Leandro et al. 2006b

Area (m2) Volume (m3)

Zone 1 2 372 800 4 887 728

Zone 2 4 017 600 3 496 352

Zone 3 592 000 374 352

Canal de Mira 6 982 400 8 758 342

Table 1. Temperature-‐dependent growth model for A.tonsa and A.clausi of Ria de Aveiro (Portugal)

Table 2. EsQmated area (m2) and water volume (m3) for Canal de Mia and each Zone. (Dias, pers. Comm)







Rainfall regime and hydrological parameters

Fig. 5 Rainfall and air temperature regime in Aveiro (July 2000 – July 2002). PrecipitaQon graph refers to the weekly accumulated rainfall and temperature curve shows the average, maximum and minimum monthly air temperature (Leandro et al 2013)

Fig. 6 Monthly mean values of (a) salinity, (b) water temperature (ºC), (c) chlorophyll a (mg m-‐3), (d) SPM (mg l-‐1), (e) POM (mg l-‐1), and Chla/SPM (mg g-‐1) in Canal de Mira (Ria de Aveiro, Portugal) between August 2000 and June 2002 (Leandro et al 2013)


Copepods biomass



Copepods produc@on


§  Secondary producQon rate, in terms of juvenile producQon, was obtained by combining in situ da ta on abundance w i th spec ific temperature-‐dependent growth models defined at food saturated condiQons.

§  This methodology is assumed to give realisQc esQmates based on studies that concluded that growth rates of juveniles under in situ condiQons are close to maximum laboratory rates determined at food saturated condiQons (Hirst & Bunker 2003).





DISCUSSION

•  The relaQve contribuQon of juvenile forms (nauplii and copepodites) to the respecQve total copepod biomass accouted to more than 54% (A.clausi) and 70% (A.tonsa).

§  This fact, in conjugaQon with the highest growth rates of juveniles compared to the adults (Hirst & Bunker 2003), supports the growing evidence that measurements of secondary producQon, based on fecundity rates and extrapolated to the enQre populaQon, certainly underesQmate the total copepod producQon.





DISCUSSION

•  The average daily juvenile secondary producQon of Acar:a populaQons was esQmated as equal to 1.208 mg C m-‐3 d-‐1, with A.tonsa represenQng more than 94%.

•  Although our approach was based only on juvenile forms, AcarQa producQon revealed to represent 32.6% (Huntley & Lopez model) to 41.7% (Hirst & Bunker model) of the total copepod community producQon of Ria de Aveiro (Leandro et al. 2007).

•  Nearly 25% of the biomass daily produced by Acar:a populaQons will be available for higher trophic levels.

Leandro SM, Morgado F, Pereira F, Queiroga H (2007) Temporal changes of abundance, biomass and producQon of copepod community in a shallow temperate estuary (Ria de Aveiro, Portugal). Estuarine Coastal and Shelf Science 74: 215-‐222, doi: 10.1016/j.ecss.2007.04.009

Huntley & Lopez model: 3.71 ± 0.540 mg C m-3

Hirst & Bunker model: 2.90 ± 0.422 mg C m-3




TAKE HOME MESSAGE


The present work was parQally supported by FCT (Portuguese FoundaQon for Science and Technology) through COMPARE Project (PTDC/MAR/121788/2010) financed by POPH (Portuguese OperaQonal Human PotenQal Program), QREN Portugal (Portuguese NaQonal Strategic Reference Framework), and MCTES (Portuguese Ministry of Science, Technology, and Higher EducaQon).

ACKNOWLEDGEMENTS


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Thank you . . .

biomass and secondary production of juvenile stages of acartia (copepoda: calanoida) populations...

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