Comanagement of small-scale fisheries and ecosystem services

Marine ecosystem services are in global decline, which requires new transformational changes in governance to cope with multiple anthropogenic stressors. We perform a systematic literature review of the biodiversity and ecosystem services outcomes of a governance transformation toward comanagement through the allocation of territorial user rights to artisanal fisher associations (TURFs) in Chile. We synthesize the implications of more than 25 years of establishing a TURF policy over ecosystem services. Results show TURFs sustain biodiversity and all typologies of ecosystem services when they are well enforced. Research on provisioning services is most prevalent, however cultural services have been gaining traction with studies assessing the role of leadership, sanctions, and social capital in determining TURF outcomes. The results suggest that TURFs can play an important role in creating social and ecological enabling conditions for local stewardship. While this is encouraging, there is a bias toward positive results and few studies address negative consequences of TURFs aimed at identifying constraints for further development. The review shows that there has been a continuous transition toward interdisciplinary social–ecological research. Research on TURFs faced with drivers of global change and uncertainty are urgently needed, in order to anticipate unintended outcomes and adapt accordingly

Field Assessment of the Predation Risk - Food Availability Trade-Off in Crab Megalopae Settlement

Settlement is a key process for meroplanktonic organisms as it determines distribution of adult populations. Starvation and predation are two of the main mortality causes during this period; therefore, settlement tends to be optimized in microhabitats with high food availability and low predator density. Furthermore, brachyuran megalopae actively select favorable habitats for settlement, via chemical, visual and/or tactile cues. The main objective in this study was to assess the settlement of Metacarcinus edwardsii and Cancer plebejus under different combinations of food availability levels and predator presence. We determined, in the field, which factor is of greater relative importance when choosing a suitable microhabitat for settling. Passive larval collectors were deployed, crossing different scenarios of food availability and predator presence. We also explore if megalopae actively choose predator-free substrates in response to visual and/or chemical cues. We tested the response to combined visual and chemical cues and to each individually. Data was tested using a two-way factorial design ANOVA. In both species, food did not cause significant effect on settlement success, but predator presence did, therefore there was not trade-off in this case and megalopae respond strongly to predation risk by active aversion. Larvae of M. edwardsii responded to chemical and visual cues simultaneously, but there was no response to either cue by itself. Statistically, C. plebejus did not exhibit a differential response to cues, but reacted with a strong similar tendency as M. edwardsii. We concluded that crab megalopae actively select predator-free microhabitat, independently of food availability, using chemical and visual cues combined. The findings in this study highlight the great relevance of predation on the settlement process and recruitment of marine invertebrates with complex life cycles

Mean settlement success based on response to chemical and visual cues from predators for A) <i>Metacarcinus edwardsii</i> and B) <i>Cancer plebejus</i>.

<p>Different letters over bars indicate homogeneous groups across treatments(<i>P</i><0.05) via Fisher-LSD post-hoc test. Error bars indicate standard deviation.</p

Three-way ANOVA for testing differences in settlement success of two Cancrid crabs on different scenarios of predator presence and food availability in different trials.

<p>Three-way ANOVA for testing differences in settlement success of two Cancrid crabs on different scenarios of predator presence and food availability in different trials.</p

Mean settlement success based on predator presence and food availability scenarios for A) Metacarcinus edwardsii and B) Cancer plebejus megalopae.

<p>Different letters over bars indicate homogeneous groups within the different predation levels (food pooled) via Fisher-LSD post-hoc test. Error bars indicate standard deviation.</p

Experimental treatments to evaluate mechanisms of detection and avoidance of potential predators.

<p>Control and treatments were collectors with A) chelae-secured predators inside the PVC tubes to test response to chemical cues, B) plastic crab mimics to test visual cues; C) free chelae-secured predators to test visual and chemical cues combined; D) PVC tube control and E) collector control (only coarse sand).</p

Two-way ANOVA for testing differences in settlement success of two Cancrid crabs responding to chemical and/or visual predatory cues.

<p>Two-way ANOVA for testing differences in settlement success of two Cancrid crabs responding to chemical and/or visual predatory cues.</p

Experimental treatments to evaluate the trade-off of food availability and predator presence.

<p>Predators utilized were 1 year-old cohorts of <i>Metacarcinus edwardsii.</i> (Carapace Width  = 35±5 mm, not to scale). Exclusion mesh (non showed), which has no effect in settlement were placed in all treatments. Control and treatments were collectors with; A) only coarse sand, B) food provided, C) free predator, D) free predator with food provided, E) chelae-secured predator, F) chelae-secured predators with food provided.</p