• Gen consumption and the O2 to C conversion) is needed to fully understand the vulnerability of sea. M–2, Valiela 1995). These data were transformed to sub- surface quantum irradiance following Kirk (1983) to ac- count for the reflection at the sea surface. Valiela I (1995) Marine ecological processes, 2nd edn.
• This book includes a comprehensive review of the processes controlling marine ecosystems, communities, and populations, as well as introduces concepts, approaches, and methods in the fast-changing fields of marine ecology and oceanography.

1. Ecological Processes Impact Factor

In Tayrona National Natural Park (Colombian Caribbean), abiotic factors such as light intensity, water temperature, and nutrient availability are subjected to high temporal variability due to seasonal coastal upwelling. These factors are the major drivers controlling coral reef primary production as one of the key ecosystem services.

This offers the opportunity to assess the effects of abiotic factors on reef productivity. We therefore quantified primary net ( P n) and gross production ( P g) of the dominant local primary producers (scleractinian corals, macroalgae, algal turfs, crustose coralline algae, and microphytobenthos) at a water current/wave-exposed and-sheltered site in an exemplary bay of Tayrona National Natural Park.

A series of short-term incubations was conducted to quantify O 2 fluxes of the different primary producers during non-upwelling and the upwelling event 2011/2012, and generalized linear models were used to analyze group-specific O 2 production, their contribution to benthic O 2 fluxes, and total daily benthic O 2 production. At the organism level, scleractinian corals showed highest P n and P g rates during non-upwelling (16 and 19 mmol O 2 m −2 specimen area h −1), and corals and algal turfs dominated the primary production during upwelling (12 and 19 mmol O 2 m −2 specimen area h −1, respectively).

At the ecosystem level, corals contributed most to total P n and P g during non-upwelling, while during upwelling, corals contributed most to P n and P g only at the exposed site and macroalgae at the sheltered site, respectively. Despite the significant spatial and temporal differences in individual productivity of the investigated groups and their different contribution to reef productivity, differences for daily ecosystem productivity were only present for P g at exposed with higher O 2 fluxes during non-upwelling compared to upwelling.

Ecological Applications, 17(5) Supplement, 2007, pp. S17–S30 2007 by the Ecological Society of America NLOAD: AN INTERACTIVE, WEB-BASED MODELING TOOL FOR NITROGEN MANAGEMENT IN ESTUARIES JENNIFER L. BOWEN, 1 JOY M. RAMSTACK,2 S. MAZZILLI,3 AND IVAN VALIELA 1,4 Boston University Marine Program, Marine Biological Laboratory, Woods Hole.

Our findings therefore indicate that total benthic primary productivity of local autotrophic reef communities is relatively stable despite the pronounced fluctuations of environmental key parameters. This may result in higher resilience against anthropogenic disturbances and climate change and Tayrona National Natural Park should therefore be considered as a conservation priority area. Seasonality in water temperature, salinity and nitrate availability in Gayraca Bay. Therefore, the goals of the study were to (1) identify dominant functional groups of benthic primary producers and their relative benthic cover at a current/wave-exposed (EXP) and -sheltered (SHE) site in one exemplary bay of TNNP, (2) quantify O 2 fluxes of all dominant benthic primary producers and apply 3D surface area estimations, and hence (3) estimate the specific contribution of each group to total benthic O 2 fluxes. Study site and sampling seasons This study was conducted in Gayraca Bay (11.33°N, 74.11°W), one of several smaller bays in TNNP, located near the city of Santa Marta. The continental shelf in the area is relatively narrow due to the proximity to the Sierra Nevada de Santa Marta–the world’s highest coastal mountain range.

The TNNP contains small fringing coral reefs reaching to a water depth of ∼30 m (; ). The region is subjected to strong seasonality caused by the Caribbean Low-Level Jet of northeast (NE) trade winds (; ), resulting in two major seasons; a dry season from December to April and a rainy season from May to November (; ).

Whereas the rainy season (non-upwelling) is characterized by low wind velocities (mean 1.5 m s −1) and high precipitation (80% of the annual rainfall) , during the dry season (upwelling), strong winds prevail (mean 3.5 m s −1, max 30 m s −1) (; ) resulting in a seasonal coastal upwelling. The upwelling-related changes in key water parameters are well characterized by the comprehensive study of. During upwelling, water temperature can decrease to 20 °C while salinity and nitrate availability increase up to 39 and 3.59 µmol L −1, respectively. Water currents triggered by prevailing winds predominantly move from NE to SW, and a clear gradient in wave exposure between the exposed western (EXP) and -sheltered northeastern (SHE) sides of the bay can be observed (; ).The study was carried out during non-upwelling in 2011 (1st November–2nd December 2011) and during the consecutive upwelling event (20th March–29th March 2012), allowing for the investigation of the influence of seasonality on benthic primary production. Benthic assessment For the assessment of benthic community structure, the dominant groups of benthic primary producers and the percentage of benthic cover were identified at EXP and SHE prior to primary production measurements using line point intercept transects at a water depth of 10 m (50 m length, n = 3), modified from.

Benthic cover was monitored at 0.5 m intervals directly below the measurement points (101 data points per transect). The dominant benthic autotrophs at the study sites consisted of scleractinian corals, frondose macroalgae, algal turfs (multispecific assemblage of primarily filamentous algae of up to 1 cm height, sensu ), crustose coralline algae (CCA), and sand potentially associated with microphytobenthos. These categories represented 97 ± 1% of the total seafloor coverage at SHE and 91 ± 2% at EXP and were therefore selected as representative primary producers for the subsequent incubation experiments. During benthic community assessment, rugosity was determined at both sites using the chain method described. Rugosity was quantified along three 10 m sub-transects within each of the 50 m transects and were used to calculate the rugosity factor for each study site as described by (SHE: 1.53 ± 0.12, EXP: 1.32 ± 0.13).

Sampling of organisms Specimens of scleractinian corals, macroalgae, algal turfs, and CCA as well as sand samples, from 10 ± 1 m water depth were used for quantification of O 2 fluxes (see for number of replicates). All samples were brought to the water surface in Ziploc ® bags and transported directly to the field laboratory. Scleractinian corals of the genera Montastraea (including the species M.

Faveolata, M. Franksi and M. Annularis, currently belonging to the genus Orbicella; ) and Diploria (including D.

Strigosa, currently belonging to the genus Pseudodiploria ) accounted for more than 80% of the total coral cover at the study sites and were therefore used as representative corals in our study. Coral specimens were obtained from the reef using hammer and chisel, fragmented with a multifunction rotary tool (8,200–2/45; mean fragment surface area: 13.16 ± 7.96 cm 2, Dremel Corp.), and fixed on ceramic tiles using epoxy glue (Giesemann GmbH, Aquascape). After fragmentation, specimens were returned to their natural habitat and left to heal for one week prior to the incubation experiments.

Algae of the genus Dictyota (mainly D. Bartayresiana) amounted to nearly 100% of macroalgal cover. Therefore small bushes of Dictyota spp.

(surface area 1.86 ± 0.88 cm 2) were used as representatives for macroalgae. Macroalgae were transferred to a storage tank (volume: 500 L in which water was exchanged manually 3–5 times per day and water temperature was within the ranges of incubation experiments; ) one day before incubation experiments and left to heal. All other functional groups were incubated immediately after sampling. Rubble overgrown by algal turfs and CCA served as samples for the respective functional group (surface area covered by the organisms: 15.63 ± 10.80 cm 2 and 7.48 ± 3.60 cm 2, respectively). For sand samples, custom-made mini corers with defined surface area (1.20 cm 2) and sediment core depth (1.0 cm) were used. All necessary permits (DGI-SCI-BEM-00488) were obtained by Instituto de Investigaciones Marinas y Costeras (INVEMAR) in Santa Marta, Colombia which complied with all relevant regulations. Surface area quantification Digital photographs of coral specimens were used to quantify planar projected surface areas of samples by image-processing software (ImageJ, V.

1.46r, National Institute of Health). The 3D surface area of the samples was estimated via multiplication of the planar projected surface areas by the genera-specific 2D to 3D surface area conversion factors derived from computer tomography measurements of Diploria and Montastraea skeletons (2.28 ± 0.16 and 1.34 ± 0.56, respectively), as described. Planar leaf area of spread out macroalgal specimens was likewise quantified by digital image analysis and multiplied by the factor 2 to obtain 3D surface area of the samples. Image analysis of in situ photographs and whole spread out macroalgal thalli were used to obtain covered substrate areas (2D surface) as well as 3D surface areas in order to calculate the 2D to 3D conversion factor for macroalgae (4.29 ± 0.82).

This conversion factor was used to correct for the overlap of macroalgal tissue. The 2D surface area of algal turf samples was determined by image analysis of digital photographs. For CCA, the simple geometry method described by was used to estimate the surface area of overgrown pieces of rubble. The obtained surface areas were related to the planar projected surface area of the samples to generate 2D to 3D conversion factors for CCA (2.10 ± 0.89). Specimen surface area for sand samples was defined by the size of the utilized mini corer (1.20 cm 2). Incubation Experiments Prior to incubation experiments, water temperature (°C) and light intensity (lx) were monitored at the sampling sites with intervals of 2 min using light and temperature loggers (Onset HOBO Pendant UA-002-64) in order to adjust light and temperature during incubations to in situ conditions.

The availability of light during light incubations was adjusted to the in situ light regimes using net cloth. Temperature and light intensity was continuously monitored during incubations as described above. Light intensities were converted to photosynthetically active radiation (PAR, µmol photons m −2 s −1, 400–700 nm) using the approximation of. Light availability was generally higher during the upwelling event ( t-test, p. Data analyses and statistics To quantify net O 2 production ( P n) and respiration of functional groups, O 2 concentration before incubations was subtracted from concentration after incubations and blank control values were subtracted from the measured O 2 fluxes. Individual gross O 2 production ( P g) of investigated functional groups was calculated by adding values of P n and respiration; individual O 2 fluxes were expressed as mmol O 2 m −2 specimen surface area h −1. The contribution of each functional group to total reef production (given as: mmol O 2 m −2 seafloor area h −1) was estimated as follows.

C i = p i s i b i r taking into account the individual production rates ( p i), the respective mean 2D to 3D surface conversion factor ( s i), group-specific benthic coverage ( b i) as well as the rugosity factor ( r). Estimation of total daily benthic productivity was furthermore calculated by summing up the contribution of the investigated groups and extrapolating the incubation periods to a 12 h light and 12 h dark cycle. After testing for normal distribution (Kolmogorov-Smirnoff test) and homogeneity of variances (Levene test), benthic coverage of functional groups were analyzed using two-way ANOVA and Bonferroni’s post hoc tests to detect possible effects of season (upwelling vs. Non-upwelling) and site (EXP vs. SHE) and their interaction on benthic cover. We tested the influence of benthic groups, season, wave exposure, and their interactions on O 2 productivity by generalized linear models (GLMs) for individual P n and P g of the investigated groups, their contribution to reef metabolism as well as total benthic productivity. We used Markov-chain Monte Carlo (MCMC) estimations of GLM regression coefficients.

In traditional Frequentist statistics, the parameters of interest (i.e., the O 2 productivity describing regression coefficients) are estimated just once (e.g., using Maximum-Likelihood) and their significance is inferred indirectly based on a test-statistic. In contrast, Bayesian methods reallocate the coefficients across a set of possible candidates during each MCMC generation. If the bulk of these values, that is the 95% highest posterior density (HPD), does not include zero, one can directly conclude that the regression coefficient is credible different than zero and an effect on O 2 productivity exists. Moreover, we here performed pair-wise comparisons between benthic groups at different sites and seasons, traditionally being performed by post-hoc testing with P-value correction for preventing false positive results. A Bayesian GLM does not suffer this drawback because difference of groups can be directly estimated by the posterior. Again, there is credible evidence in non-equal group-means, if the posterior-based 95% HPD interval of the group differences does not include zero. Model performance for all 19 possible combinations of the three independent variables and their interactions was assessed by the deviance information criterion (DIC), a Bayesian measure of model fit that penalizes complexity.

In this information theory based model selection, often there is not a single best model describing the data. Therefore, averaging of regression coefficients for all models within ΔDIC. Benthic community composition At EXP, scleractinian corals dominated the benthic community during non-upwelling and upwelling (41 ± 12 and 39 ± 12%, respectively; ).

At SHE, corals, algal turf, and sand cover was similar during non-upwelling (24 ± 3%, 26 ± 6%, and 25 ± 13%, respectively), while during upwelling, macroalgae exhibited highest benthic cover (47 ± 3%, ). During the entire study period, coral and CCA cover was significantly higher at EXP than at SHE, whereas sand showed a contrary pattern with significantly more coverage at SHE. Macroalgae was the only group where interaction between sites and seasons occurred with significantly higher cover at SHE and higher abundances during upwelling at both sites. CCA cover also differed between the seasons, showing a significant decrease during the upwelling event. O 2 fluxes of organisms More complex Bayesian GLMs, including interactions among the three independent variables season, benthic group, and site, described individual O 2 fluxes better than simple models (For details see ).

Of all investigated functional groups, scleractinian corals had highest individual net ( P n) and gross production ( P g), followed by algal turfs, macroalgae, CCA, and microphytobenthos (; see also for detailed results of all pair-wise comparisons). Regarding spatial differences in individual productivity, significant differences were detected for algal turfs and CCA.

During upwelling, P n of algal turfs and P g of CCA was higher at SHE than EXP. On the contrary, during non-upwelling, P n and P g of CCA was higher at EXP. Contribution of organism-induced O 2 fluxes to total reef O 2production As in the case of individual O 2 fluxes, contribution and total reef production were better explained by GLMs of higher complexity. Contribution of functional groups to benthic productivity exhibited similar pattern than individual productivity with corals contributing generally most to total reef P n and P g, but macroalgae contributed most to benthic P n and P g at SHE at the end of upwelling (; see also for detailed results of all pair-wise comparisons). Contribution of functional groups to benthic net and gross production. Significant spatial differences in contribution to total benthic P n within functional groups were detected for corals, algal turf, and macroalgae, and spatial differences for P g were present in all investigated groups except CCA. At EXP, Corals contributed more to total P n and P g during non-upwelling and upwelling.

At SHE, contributions of macroalgae ( P n and P g) and microphytobenthos ( P g) were higher only during upwelling, and algal turfs contributed more to P g at SHE during non-upwelling. Temporal differences in contribution to total benthic productivity within the investigated groups were present for corals, macroalgae, CCA (for P n and P g), and for algal turfs (only P g). During non-upwelling, corals contributed more to the total productivity at SHE and CCA at EXP, whereas during upwelling, macroalgae contributed more to the total productivity at SHE and algal turf at EXP. Total benthic net and gross production. Regarding the total daily benthic O 2 fluxes , no spatial differences between EXP and SHE were detected, neither during non-upwelling nor during upwelling (see also for detailed results of all pair-wise comparisons). During the study, significant temporal differences were only present for P g at the exposed site with higher O 2 fluxes during the upwelling in 2011/2012 compared to non-upwelling.

Comparing total benthic productivity during the upwelling event in 2010/2011 with the subsequent non-upwelling and upwelling, P n and P g were significantly higher during the upwelling 2010/2011 for all comparisons. O 2 fluxes of organisms Individual mean P n and P g were generally highest for corals at both sites during the study periods ( P n: 11.2–16.1 and P g: 17.4–20.8 mmol O 2 m −2 specimen area h −1). These high productivity rates of corals compared to other investigated primary producers (see ) may be attributed to the mutualistic relationship between zooxanthellae and coral host leading to enhanced photosynthetic efficiency under high CO 2 and nutrient availability (; ). Estimated daily P g per m 2seafloor for the investigated coral genera, (441–610 mmol O 2 m −2 seafloor d −1), is within the range of other Caribbean corals (67–850 mmol O 2 m −2 seafloor d −1, ), and O 2 fluxes of all investigated organism groups are comparable to values reported in the literature. Significant spatial differences during non-upwelling were found for CCA with higher productivity at EXP compared to SHE. These differences may be attributed to the prevailing water current regime in the bay together with high water temperatures during non-upwelling ( and ). An increase in water temperature typically intensifies metabolic activity in CCA (; ).

However, the lower water flow at SHE may have prevented the required gas exchange and nutrient uptake, resulting in lower individual CCA productivity at this site. In contrast, the higher rates in individual productivity of algal turfs and CCA at SHE during upwelling are potentially a result of the differences in species composition (sensu;;; ). Temporal differences in individual O 2 production within the investigated organism groups generally showed two contrary patterns: whereas scleractinian corals on both sites and CCA at EXP produced less O 2 during upwelling, algal turfs and CCA at SHE produced more O 2. The decreased productivity rates of corals and CCA at EXP during upwelling indicate that low water temperature has an adverse effect on the productivity of these groups. This argument is supported by studies showing that low water temperatures lead to a decrease in photosynthetic performance of primary producers in coral reefs (; ). In contrast, the two-fold higher photosynthetic performance of algal turfs during upwelling may be due to higher nutrient concentrations together with higher water currents during this season (; ), facilitating gas exchange and nutrient uptake.

Our findings are supported by, showing that photosynthesis of algal turfs in coral reefs is mainly limited by nutrient uptake, which in turn depends on nutrient availability and water current speed. Whereas productivity of CCA at EXP seems to be temperature-limited, our findings indicate that their productivity at SHE is limited by nutrient availability as previously suggested for benthic algal communities in water current-sheltered coral reef locations (; ). Contribution of organism-induced O 2 fluxes to total benthic O 2 production Our results indicate that the spatial differences in contribution to total benthic O 2 production for scleractinian corals, macroalgae, CCA, and microphytobenthos are directly linked to spatial differences in their benthic coverage. For instance, the major contribution of corals can be explained by their comparably high benthic coverage (ranging from 24 to 39%; ) and highest quantified individual O 2 production rates among all investigated groups. This finding is supported by the estimates of, showing that corals accounted for about two-thirds of the total benthic primary production in a Southern Caribbean fringing reef.

Although individual macroalgal production rates were rather low as compared to coral productivity , the extremely high cover of macroalgae at SHE during upwelling (47 ± 3%, ) resulted in macroalgae being the main contributors to total benthic production. Macroalgal cover (incl. The dominant genus Dictyota) has previously been found to be particularly high during upwelling (;; ) probably due to elevated nutrient concentrations and low water temperatures. The elevated contributions of corals and CCA at EXP as well as macroalgae and microphytobenthos at SHE during upwelling might be due to site-specific differences in abundances , which in turn are likely caused by site-specific differences in water current regimes (; ). Corals, macroalgae, algal turfs, and CCA also exhibited distinct temporal differences in contribution to total benthic productivity.

At SHE, corals contributed more to the benthic O 2 production during non-upwelling and macroalgae and algal turfs during upwelling, whereas contribution of CCA at EXP was higher during non-upwelling. These differences can be explained with seasonal growth patterns, temperature-dependent changes in individual O 2 productivity and temporal shifts in abundances ( and ). Opposite abundance patterns of CCA and macroalgae are, for example, in agreement with previous studies showing that macroalgae can shade CCA, usually leading to negative correlated abundances of these groups (; ). Total benthic O 2 fluxes and ecological perspective The estimated total daily benthic O 2 production at both sites during non-upwelling and upwelling are, although comparable, on average slightly lower than the values previously reported for other fore reefs communities. These differences might be due to a methodological bias. Whereas previous studies utilized flow respirometry techniques, the current study used incubation methodology, which accounts for production values in the target groups only. Mean benthic oxygen production of reef communities and their dominant functional groups of primary producers.

Despite the high spatial and temporal differences in benthic coverage and group-specific O 2 fluxes of investigated benthic primary producers as well as their contribution to total benthic productivity, no spatial differences in total benthic O 2 fluxes were detected between EXP and SHE. These results were consistent during both non-upwelling and upwelling. Our findings are supported by, showing that the relative coverage of benthic photoautotrophs in a reef community may have little effect on its areal production rate. In TNNP, seasonal differences were only present for P g at EXP with higher rates during upwelling compared to non-upwelling. These differences are mainly related to individual productivity of algal turfs, being generally two-fold higher during upwelling compared to non-upwelling , and to the absence of macroalgae at EXP during non-upwelling.

This is in agreement with studies by and, reporting that algae, as one of the most seasonal component in coral reefs, account for seasonal shifts in benthic reef productivity. The lack of seasonality of P n and P g regarding communities at SHE as well as P g at EXP stands in contrast to earlier studies (;;; ), which found an approximately two-fold difference in benthic primary production between seasons. This lack of seasonality in P n and partly in P g might be related to seasonal changes of abiotic factors in TNNP that compensate for each other. The observed similarity in productivity rates during different seasons suggest that coral reefs in TNNP can cope with pronounced seasonal variations in light availability, water temperature, and nutrient availability.

Nevertheless, total P n and P g during the upwelling in 2010/2011 ( P n: 244–272 and P g: 476–483 mmol O 2 m −2 seafloor d −1) were not only higher compared to non-upwelling but also higher than during the subsequent upwelling in 2011/2012. These findings suggest that interannual variations affect the productivity of TNNP coral reefs. Dramatic ENSO-related water temperature increases and high precipitation in the study area (; ) led to coral bleaching at the end of 2010. Surprisingly, bleached corals in the bay recovered quickly in the course of the following upwelling event and exhibited similar O 2 production rates during all study periods , indicating a high resilience of TNNP corals.

Moreover, macroalgae and algal turf seemed to benefit from the environmental conditions during the upwelling following the ENSO-related disturbance events, resulting in higher group-specific productivity during the upwelling in 2010/2011 compared to subsequent study periods. The elevated production rates of macroalgae and algal turfs together with the quick recovery of corals from bleaching likely accounted for a higher benthic productivity during the upwelling in 2011/2011 compared to non-upwelling and the upwelling in 2011/2012. These findings indicate that extreme ENSO-related disturbances do not have long-lasting effects on the functioning of local benthic communities in TNNP. In conclusion, the present study showed that total benthic productivity in TNNP is relatively constant despite high variations in key environmental parameters. This stable benthic productivity suggests a relatively high resilience of local benthic communities against natural environmental fluctuations and anthropogenic disturbances.

We therefore recommend that TNNP should be considered as a conservation priority area. Table S2 Goodness of fit for generalized linear models: Goodness of fit for all 19 general linear models including the three independent variables benthic group, season, and site and their interactions.

Dependent variables have been individual net and gross production, contribution of functional groups to benthic net and gross production, and total daily benthic net and gross production, respectively. Grey box indicates inclusion of the independent variable in the respective model. Abbreviations: DIC, deviance information criterion delta; DIC, difference in DIC compared to the model with highest fit; DICwt, DIC weights, i.e., the support for respective the mode.

The oceans represent a vast, complex and poorly understood ecosystem. Marine Ecological Processes is a modern review and synthesis of marine ecology that provides the reader with a lucid introduction to the intellectual concepts, approaches, and methods of this evolving discipline. Comprehensive in its coverage, this book focuses on the processes controlling marine ecosystems, communities, and populations and demonstrates how general ecological principles-derived from terrestrial and freshwater systems as well-apply to marine ecosystems.

Ecological Processes Impact Factor

Global warming and increased eutrophication and wetland destruction in recent years has made the study of ecological processes even more important for the preservation of marine environments. This thoroughly updated and expanded edition will provide students of marine ecology, marine biology, and oceanography with numerous illustrations, examples, and references which clearly impart to the reader the current state of research in this field: its achievements as well as unresolved controversies.