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Destructive fishing and fisheries enforcement in eastern Indonesia
Bailey, M.L. ; Sumaila, U.R. - \ 2015
Marine Ecology Progress Series 530 (2015). - ISSN 0171-8630 - p. 195 - 211.
coral-reefs - management - economics - conservation - bioeconomics - population - illegal
A simple bioeconomic leader-follower model was constructed to simulate snapper (family Lutjanidae) and grouper (family Serranidae) fisheries in Raja Ampat, Indonesia, an area of significant coral and fish biodiversity. We developed a leader-follower game, wherein the Regency government as the leader chooses an enforcement model to discourage illegal fishing. Fishers are then given a choice to fish using legal gears, such as handlines, or to fish with illegal gears, e.g. dynamite (for snapper) or cyanide (for grouper). Given prices and costs of legal and illegal fishing, the status quo simulations with no Regency enforcement result in a large amount of illegal catch throughout the 50 yr simulation, which agrees with expert opinion that destructive illegal fishing is occurring in the region. In an attempt to include ecosystem-based management principles into Raja Ampat governance, we introduce an enforcement regime in the form of detecting and punishing illegal fishing. Results suggest that current fishing practices do not account for the disproportionate ecosystem effects of destructive fishing, and that elimination of dynamite fishing may be easier for the government due to the high profitability of the live fish trade connected with cyanide fishing.
Creating a safe operating space for iconic ecosystems
Scheffer, M. ; Barrett, S. ; Carpenter, S.R. ; Folke, C. ; Green, A.J. ; Holmgren, M. ; Hughes, T.P. ; Kosten, S. ; Leemput, I.A. van de; Nepstad, D.C. ; Nes, E.H. van; Peeters, E.T.H.M. ; Walker, B. - \ 2015
Science 347 (2015)6228. - ISSN 0036-8075 - p. 1317 - 1319.
climate-change - coral-reefs - deforestation - resilience - impacts - amazon - shifts - fire
Although some ecosystem responses to climate change are gradual, many ecosystems react in highly nonlinear ways. They show little response until a threshold or tipping point is reached where even a small perturbation may trigger collapse into a state from which recovery is difficult (1). Increasing evidence shows that the critical climate level for such collapse may be altered by conditions that can be managed locally. These synergies between local stressors and climate change provide potential opportunities for proactive management. Although their clarity and scale make such local approaches more conducive to action than global greenhouse gas management, crises in iconic UNESCO World Heritage sites illustrate that such stewardship is at risk of failing.
Cell Turnover and Detritus Production in Marine Sponges from Tropical and Temperate Benthic Ecosystems
Alexander, B.E. ; Liebrand, K. ; Osinga, R. ; Geest, H.G. van der; Admiraal, W. ; Cleutjens, J.P.M. ; Schutte, B. ; Verheyen, F. ; Ribes, M. ; Loon, E. van; Goeij, J.M. de - \ 2014
PLoS One 9 (2014)10. - ISSN 1932-6203 - 11 p.
fresh-water sponge - stem-cells - ephydatia-fluviatilis - intestinal epithelium - tissue homeostasis - coral-reefs - in-vitro - demospongiae - cycle - population
This study describes in vivo cell turnover (the balance between cell proliferation and cell loss) in eight marine sponge species from tropical coral reef, mangrove and temperate Mediterranean reef ecosystems. Cell proliferation was determined through the incorporation of 5-bromo-2'-deoxyuridine (BrdU) and measuring the percentage of BrdU-positive cells after 6 h of continuous labeling (10 h for Chondrosia reniformis). Apoptosis was identified using an antibody against active caspase-3. Cell loss through shedding was studied quantitatively by collecting and weighing sponge-expelled detritus and qualitatively by light microscopy of sponge tissue and detritus. All species investigated displayed substantial cell proliferation, predominantly in the choanoderm, but also in the mesohyl. The majority of coral reef species (five) showed between 16.1±15.9% and 19.0±2.0% choanocyte proliferation (mean±SD) after 6 h and the Mediterranean species, C. reniformis, showed 16.6±3.2% after 10 h BrdU-labeling. Monanchora arbuscula showed lower choanocyte proliferation (8.1±3.7%), whereas the mangrove species Mycale microsigmatosa showed relatively higher levels of choanocyte proliferation (70.5±6.6%). Choanocyte proliferation in Haliclona vansoesti was variable (2.8–73.1%). Apoptosis was negligible and not the primary mechanism of cell loss involved in cell turnover. All species investigated produced significant amounts of detritus (2.5–18% detritus bodyweight-1·d-1) and cell shedding was observed in seven out of eight species. The amount of shed cells observed in histological sections may be related to differences in residence time of detritus within canals. Detritus production could not be directly linked to cell shedding due to the degraded nature of expelled cellular debris. We have demonstrated that under steady-state conditions, cell turnover through cell proliferation and cell shedding are common processes to maintain tissue homeostasis in a variety of sponge species from different ecosystems. Cell turnover is hypothesized to be the main underlying mechanism producing sponge-derived detritus, a major trophic resource transferred through sponges in benthic ecosystems, such as coral reefs.
Deep-water sponges (Porifera) from Bonaire and Klein Curacao, Southern Caribbean
Soest, R.W.M. ; Meesters, H.W.G. ; Becking, L.E. - \ 2014
Zootaxa 3878 (2014)5. - ISSN 1175-5326 - p. 401 - 443.
southwestern atlantic - brazilian coast - coral-reefs - demospongiae - plakinidae
Four submersible dives off the coast of Bonaire (Caribbean Netherlands) and Klein Curaçao (Curaçao) to depths of 99.5–242 m, covering lower mesophotic and upper dysphotic zones, yielded 52 sponge specimens belonging to 31 species. Among these we identified 13 species as new to science. These are Plakinastrella stinapa n. sp., Pachastrella pacoi n. sp., Characella pachastrelloides n. sp., Geodia curacaoensis n. sp., Caminus carmabi n. sp., Discodermia adhaerens n. sp., Clathria (Microciona) acarnoides n. sp., Antho (Acarnia) pellita n. sp., Parahigginsia strongylifera n. sp., Calyx magnoculata n. sp., Neopetrosia dutchi n. sp., Neopetrosia ovata n. sp. and Neopetrosia eurystomata n. sp. We also report an euretid hexactinellid, which belongs to the rare genus Verrucocoeloidea, recently described (2014) as V. liberatorii Reiswig & Dohrmann. The remaining 18 already known species are all illustrated by photos of the habit, either in situ or ‘on deck’, but only briefly characterized in an annotated table to confirm their occurrence in the Southern Caribbean. The habitat investigated—steep limestone rocks, likely representing Pleistocene fossil reefs—is similar to deep-water fossil reefs at Barbados of which the sponges were sampled and studied by Van Soest and Stentoft (1988). A comparison is made between the two localities, showing a high degree of similarity in sponge composition: 53% of the present Bonaire-Klein Curaçao species were also retrieved at Barbados. At the level of higher taxa (genera, families) Bonaire-Klein Curaçao shared approximately 80% of its lower mesophotic and upper dysphotic sponge fauna with Barbados, despite a distance between them of 1000 km, indicating high faunal homogeneity. We also preliminarily compared the shallow-water (euphotic) sponge fauna of Curaçao with the combined data available for the Barbados, Bonaire and Klein Curaçao mesophotic and upper dysphotic sponges, which resulted in the conclusion that the two faunas show only little overlap.
A baseline water quality assessment of the coastal reefs of Bonaire, Southern Caribbean
Slijkerman, D.M.E. ; León, R. de; Vries, P. de - \ 2014
Marine Pollution Bulletin 86 (2014)1-2. - ISSN 0025-326X - p. 523 - 529.
urchin diadema-antillarum - coral-reefs - netherlands-antilles - nutrient enrichment - curacao - eutrophication - nitrogen - decline
Bonaire is considered to harbor some of the best remaining coral reefs of the Caribbean, but faces multiple pressures including eutrophication. We measured multiple water quality indicators twice annually, from November 2011 to May 2013, at 11 locations at the west coast of Bonaire. This study resulted in 834 data points. DIN concentrations ranged from below quantification to 2.69 µmol/l, phosphate from below quantification to 0.16 µmol/l, and chlorophyll-a from 0.02 to 0.42 µg/l. Several indicators showed signs of eutrophication, with spatial and temporal effects. At southern and urban locations threshold levels of nitrogen were exceeded. This can be a result of brine leaching into sea from salt works and outflow of sewage water. Chlorophyll-a showed an increase in time, and phosphorus seemed to show a similar trend. These eutrophication indicators are likely to exceed threshold levels in near future if the observed trend continues. This is a cause for concern and action.
Toward Principles for Enhancing the Resilience of Ecosystem Services
Biggs, R. ; Schlüter, M. ; Biggs, D. ; Bohensky, E.L. ; BurnSilver, S. ; Cundill, G. ; Dakos, V. ; Daw, T.M. ; Evans, L.S. ; Kotschy, K. ; Leitch, A.M. ; Meek, C. ; Quinlan, A. ; Raudsepp-Hearne, C. ; Robards, M.D. ; Schoon, M.L. ; Schultz, L. ; West, P.C. - \ 2012
Annual Review of Environment and Resources 37 (2012)10. - ISSN 1543-5938 - p. 421 - 448.
social-ecological-systems - complex adaptive systems - natural-resource management - great-barrier-reef - response diversity - protected areas - climate-change - river-basin - coral-reefs - networks
Enhancing the resilience of ecosystem services (ES) that underpin human well-being is critical for meeting current and future societal needs, and requires specific governance and management policies. Using the literature, we identify seven generic policy-relevant principles for enhancing the resilience of desired ES in the face of disturbance and ongoing change in social-ecological systems (SES). These principles are (P1) maintain diversity and redundancy, (P2) manage connectivity, (P3) manage slow variables and feedbacks, (P4) foster an understanding of SES as complex adaptive systems (CAS), (P5) encourage learning and experimentation, (P6) broaden participation, and (P7) promote polycentric governance systems. We briefly define each principle, review how and when it enhances the resilience of ES, and conclude with major research gaps. In practice, the principles often co-occur and are highly interdependent. Key future needs are to better understand these interdependencies and to operationalize and apply the principles in different policy and management contexts
The resilience and resistance of an ecosystem to a collapse of diversity
Downing, A.S. ; Nes, E.H. van; Mooij, W.M. ; Scheffer, M. - \ 2012
PLoS One 7 (2012)9. - ISSN 1932-6203
lake victoria - stable states - east-africa - coral-reefs - nile perch - food-web - biodiversity - productivity - communities - populations
Diversity is expected to increase the resilience of ecosystems. Nevertheless, highly diverse ecosystems have collapsed, as did Lake Victoria's ecosystem of cichlids or Caribbean coral reefs. We try to gain insight to this paradox, by analyzing a simple model of a diverse community where each competing species inflicts a small mortality pressure on an introduced predator. High diversity strengthens this feedback and prevents invasion of the introduced predator. After a gradual loss of native species, the introduced predator can escape control and the system collapses into a contrasting, invaded, low-diversity state. Importantly, we find that a diverse system that has high complementarity gains in resilience, whereas a diverse system with high functional redundancy gains in resistance. Loss of resilience can display early-warning signals of a collapse, but loss of resistance not. Our results emphasize the need for multiple approaches to studying the functioning of ecosystems, as managing an ecosystem requires understanding not only the threats it is vulnerable to but also pressures it appears resistant to
Suspended sediment load in the tidal zone of an Indonesian river
Buschman, F.A. ; Hoitink, A.J.F. ; Jong, F.M. de; Hoekstra, P. ; Hidayat, H. ; Sassi, M.G. - \ 2012
Hydrology and Earth System Sciences 16 (2012). - ISSN 1027-5606 - p. 4191 - 4204.
coral-reefs - east kalimantan - hbv model - r-factor - soil - erosion - runoff - flux - catchment - impacts
Forest clearing for reasons of timber production, open pit mining and the establishment of oil palm plantations generally results in excessively high sediment loads in tropical rivers. The increasing sediment loads pose a threat to coastal marine ecosystems, such as coral reefs. This study presents observations of suspended sediment loads in the Berau River (Kalimantan, Indonesia), which debouches into a coastal ocean that is a preeminent center of coral diversity. The Berau River is relatively small and drains a mountainous, still relatively pristine basin that receives abundant rainfall. In the tidal zone of the Berau River, flow velocity was measured over a large part of the river width using a horizontal acoustic Doppler current profiler (HADCP). Surrogate measurements of suspended sediment concentration were taken with an optical backscatter sensor (OBS). Averaged over the 6.5 weeks covered by the benchmark survey period, the suspended sediment load was estimated at 2 Mt yr-1. Based on rainfall-runoff modeling though, the river discharge peak during the survey was supposed to be moderate and the yearly averaged suspended sediment load is most likely somewhat higher than 2 Mt yr-1. The consequences of ongoing clearing of rainforest were explored using a plot-scale erosion model. When rainforest, which still covered 50–60% of the basin in 2007, is converted to production land, soil loss is expected to increase with a factor between 10 and 100. If this soil loss is transported seaward as suspended sediment, the increase in suspended sediment load in the Berau River would impose a severe stress on this global hotspot of coral reef diversity.
Increased recruitment rates indicate recovering populations of the sea urchin Diadema antillarum on Curacao
Vermeij, M. ; Debrot, A.O. ; Hal, N. van der; Bakker, J. ; Bak, R.P.M. - \ 2010
Bulletin of Marine Science 86 (2010)3. - ISSN 0007-4977 - p. 719 - 725.
mass mortality - coral-reefs - tripneustes-ventricosus - netherlands-antilles - community structure - philippi - density - echinodermata - degradation - echinoidea
Recruitment of the sea urchin Diadema antillarum philippi, 1845 was studied on artificial recruitment panels along the leeward coast of the island of Curaçao, southern Caribbean. Data were compared with historical data from the same coast that were collected before (1982-1983) and after (1984) the Caribbean-wide mass mortality of Diadema in October 1983. Average recruitment rates observed in 2005 were equal to 2.2 times lower compared to those observed before the D. antillarum die-off (1982 and 1983), but 56.5 times higher than those observed after the die-off in 1984. The increase in recruitment rates between 1984 and 2005 was 5-51 times greater than the increase in abundance of adult individuals over the same period. This suggests that despite the largely recovered recruitment rates of this important reef herbivore, unknown sources of high post-settlement mortality currently prevent a similar recovery of its adult population
Exploring industry specific social welfare maximizing rates of water pollution abatement in linked terrestrial and marine ecosystems
Roebeling, P.C. ; Hendrix, E.M.T. ; Grieken, M.E. van - \ 2009
Journal of Coastal Research 2009 (2009)SI 56. - ISSN 0749-0208 - p. 1681 - 1685.
coastal ecosystems - coral-reefs - baltic sea - land - catchments - management - runoff
Marine ecosystems are severely affected by water pollution originating from coastal catchments, while these ecosystems are of vital importance from an environmental as well as an economic perspective. To warrant sustainable economic development of coastal regions, we need to balance the marginal costs from coastal catchment water pollution abatement and the associated marginal benefits from marine resource appreciation. Water pollution abatement costs are, however, not equal across industries and, consequently, the question arises to what extent marine water quality improvement can efficiently be pursued across industries. In this paper we develop an optimal control approach to explore, analytically as well as quantitatively, social welfare maximizing rates of water pollution abatement across industries. For a case study of Dissolved Inorganic Nitrogen (DIN) water pollution in the Great Barrier Reef region of Australia, water pollution abatement cost functions for two agricultural industries are estimated to, in turn, explore social welfare maximizing rates of water pollution abatement per industry. Results for the Tully-Murray catchment show that DIN water pollution can be reduced by about 25% through the adoption of win-win management practices in the sugarcane industry. However, when taking into account the benefits from reduced DIN water pollution in the downstream marine environment, this study shows that maximum social welfare gains can be obtained by reducing DIN water pollution through a reduction in the agricultural production area in combination with the adoption of lose-win management practices in the sugarcane as well as the grazing industry.
Effects of Great Barrier Reef degradation on recreational reef-trip demand: a contingent behaviour approach
Kragt, M.E. ; Roebeling, P.C. ; Ruijs, A.J.W. - \ 2009
The Australian Journal of Agricultural and Resource Economics 53 (2009)2. - ISSN 1364-985X - p. 213 - 229.
coral-reefs - travel cost - quality improvements - stated preference - nonmarket goods - florida-keys - valuation - responses - models - benefits
There is a growing concern that increased nutrient and sediment runoff from river catchments are a potential source of coral reef degradation. Degradation of reefs may affect the number of tourists visiting the reef and, consequently, the economic sectors that rely on healthy reefs for their income generation. This study uses a contingent behaviour approach to estimate the effect of reef degradation on demand for recreational dive and snorkel trips, for a case study of the Great Barrier Reef in Australia. Results from a negative binomial random effects panel model show that the consumer surplus current reef visitors derive from a diving or snorkelling trip is approximately A$185 per trip. Furthermore, results indicate that reef trips by divers and snorkellers could go down by as much as 80 per cent given a hypothetical decrease in coral and fish biodiversity. This corresponds to a decrease in tourism expenditure by divers and snorkellers on full-day reef trips in the Cairns management area of the Great Barrier Reef Marine Park of about A$103 million per year.
Pulse driven loss of top-down control: The critical-rate hypothesis
Scheffer, M. ; Nes, E.H. van; Holmgren, M. ; Hughes, T. - \ 2008
Ecosystems 11 (2008)2. - ISSN 1432-9840 - p. 226 - 237.
exploitation ecosystems - climate-change - coral-reefs - el-nino - stability - shifts - photosynthesis - cyanobacteria - productivity - degradation
In systems ranging from lakes and woodlands to coral reefs, the long-term ecosystem state may often be determined largely by rare extreme events such as wet ENSO years, droughts, or disease outbreaks. Such events can flip these systems into a contrasting state that represents either an alternative attractor or a transient that is slow enough to persist even if the frequency of events that push the system to this state is low. Here we show that escape from herbivores is a mechanism that can play a role in several state shifts of this kind. This can happen if plants become less susceptible to herbivory as they grow. Using a model we show that, surprisingly, this mechanism can lead to a situation where a brief resource pulse for plants may invoke a persistent shift to a high biomass state whereas gradual enrichment to the same resource level is insufficient to allow such a change. This counterintuitive phenomenon occurs if the numerical response of herbivores is sufficiently slow to allow the plants to use the resource pulse to escape to a safe biomass at which herbivory is reduced. Our results imply that rates of environmental change can sometimes be more important than their magnitude. This has many ramifications. On the conceptual side, our findings suggest that key mechanisms that regulate long-term ecosystem dynamics are easily missed by the traditional focus of modelers on equilibria. A more practical corollary is that increased climatic variability may have more profound effects in some ecosystems than gradual change in conditions.
Response of secondary production and its components to multiple stressors in nematode field populations.
Doroszuk, A. ; Brake, E. te; Crespo-Gonzalez, D. ; Kammenga, J.E. - \ 2007
Journal of Applied Ecology 44 (2007)2. - ISSN 0021-8901 - p. 446 - 455.
life-history - caenorhabditis-elegans - macroinvertebrate production - acrobeloides-nanus - ecosystem function - nitrogen budgets - mountain streams - soil nematodes - coral-reefs - biodiversity
Realistic measures of the impact of individual or multiple stressors are important for ecological risk assessment. Although multiple anthropogenic stressors are common in human-dominated environments, knowledge of their influence on functional population parameters such as secondary production (P) and biomass turnover (P/B) is very limited. Secondary production integrates population characteristics such as biomass, size¿frequency distribution and body growth rate, and provides a link between population and system ecologies. 2. The influence of copper and pH stress on yearly secondary production and biomass turnover of field populations of the nematode Acrobeloides nanus was investigated by using a randomized factorial block design. The responses of the components of secondary production were also analysed in order to elucidate the mechanisms underlying the change in secondary production. 3. Secondary production and biomass turnover showed reduced values in soil of low pH. A negative effect of copper on both parameters was observed only when the copper load was combined with low pH, otherwise higher copper concentrations resulted in higher secondary production and biomass turnover. 4. The observed response of production and biomass turnover was mainly driven by changes in mean relative growth rate (MRGR), a measure of body growth rate estimated in a laboratory soil experiment. The biomass was higher on average in the plots with high copper load, while no significant response to pH was found. 5. Synthesis and applications. Our results demonstrate that populations of soil organisms may experience strong synergistic effects of combined stressors (acidification and copper stress) on functional population parameters while showing no detrimental effects on biomass. Moreover, the effects on secondary production and biomass turnover rate are predominantly driven by effects on body growth rate. We recommend that ecological risk assessment methodologies should include consideration of soil contamination on the basis of conservation of functional properties of ecosystems and their key components
Cumulative impacts of seabed trawl disturbance on benthic biomass, production, and species richness in different habitats
Hiddink, J.G. ; Jennings, S. ; Kaiser, M.J. ; Queiros, A.M. ; Duplisea, D.E. ; Piet, G.J. - \ 2006
Canadian Journal of Fisheries and Aquatic Sciences 63 (2006)4. - ISSN 0706-652X - p. 721 - 736.
soft-sediment communities - mobile fishing gear - southern north-sea - ecosystem function - coral-reefs - macrofauna - shelf - size - bioturbators - assemblages
Bottom trawling causes widespread disturbance of sediments in shelf seas and can have a negative impact on benthic fauna. We conducted a large-scale assessment of bottom trawl fishing of benthic fauna in different habitats, using a theoretical, size-based model that included habitat features. Species richness was estimated based on a generalized body mass versus species richness relationship. The model was validated by sampling 33 stations subject to a range of trawling intensities in four shallow, soft sediment areas in the North Sea. Both the model and the field data demonstrated that trawling reduced biomass, production, and species richness. The impacts of trawling were greatest in areas with low levels of natural disturbance, while the impact of trawling was small in areas with high rates of natural disturbance. For the North Sea, the model showed that the bottom trawl fleet reduced benthic biomass and production by 56% and 21%, respectively, compared with an unfished situation. Because of the many simplifications and assumptions required to synthesize these data, additional work is required to refine the model and evaluate applicability in other geographic areas. Our model enables managers to understand the consequences of altering the distribution of fishing activities on benthic production and hence on food web processes.
Observations of suspended sediment from ADCP and OBS measurements in a mud-dominated environment
Hoitink, A.J.F. ; Hoekstra, P. - \ 2005
Coastal Engineering 52 (2005)2. - ISSN 0378-3839 - p. 103 - 118.
banten nw java - acoustic backscatter - optical backscatter - ocean measurements - settling velocity - coral-reefs - sound - sand - size - transport
The ability of a 1.2-MHz Acoustic Doppler Current Profiler (ADCP) to measure suspended sediment concentration (SSC) and particle size variation in a mud-dominated environment has been investigated. Experiments were conducted in the Bay of Banten, Indonesia, where clays and silts in the range of 3-55 ¿m are prevalent. The ADCP backscatter depends both on SSC and on the size of the scatterers. Over the time span of several separate deployments, which lasted 20 days at most, SSC was found to be proportional to the acoustically normative grain size squared. Using this relation, the ADCP could be calibrated to yield depth profiles of SSC. The obtained calibrations, however, were spatially and seasonally dependent. Differences between the calibrations could not be completely ascribed to variation in grain size distributions, due to the largely unknown influences of aggregates and organic scatterers. The ADCP backscatter measurements provided insight into diurnal events of erosion and subsequent deposition. An increase or decrease of SSC generally coincided with a raise or decline of the average grain size in the sediment suspension (respectively).
Regime shifts, resilience, and biodiversity in ecosystem management
Folke, C. ; Carpenter, S. ; Walker, B. ; Scheffer, M. ; Elmqvist, T. ; Gunderson, L. ; Holling, C.S. - \ 2004
Annual Review of Ecology, Evolution, and Systematics 35 (2004). - ISSN 1543-592X - p. 557 - 581.
alternative stable states - coral-reefs - baltic sea - species-diversity - phase-shifts - trophic cascades - climate-change - shallow lakes - el-nino - vegetation
We review the evidence of regime shifts in terrestrial and aquatic environments in relation to resilience of complex adaptive ecosystems and the functional roles of biological diversity in this context. The evidence reveals that the likelihood of regime shifts may increase when humans reduce resilience by such actions as removing response diversity, removing whole functional groups of species, or removing whole trophic levels; impacting on ecosystems via emissions of waste and pollutants and climate change; and altering the magnitude, frequency, and duration of disturbance regimes. The combined and often synergistic effects of those pressures can make ecosystems more vulnerable to changes that previously could be absorbed. As a consequence, ecosystems may suddenly shift from desired to less desired states in their capacity to generate ecosystem services. Active adaptive management and governance of resilience will be required to sustain desired ecosystem states and transform degraded ecosystems into fundamentally new and more desirable configurations.