The Lessonia nigrescens fishery in northern Chile: “how you harvest is more important than how much you harvest”
Vásquez, J., Piaget, N., & Vega, J.
In Chile, management of natural resources usually starts right before its imminent collapse or after evident declination. In the northern area of the country, the fishery of brown seaweeds has an enormous social, ecological, and economical importance. More than 11,000 people depend directly or indirectly on the collection and harvesting of this resource. Ecologically, kelps constitute areas for food, reproduction, and refuge for hundreds of invertebrates and fish species. Economically, landings up to 300,000 dry tons per year represent close to US $60 million for the industry. Until 2002, the Chilean brown seaweed fishery was mainly sustained by natural mortality, where plants cast ashore were collected by artisanal fishermen. Since then, three brown seaweed species of economic importance (Lessonia nigrescens, Lessonia trabeculata, and Macrocystis pyrifera) have been intensively harvested in coastal areas between 18° and 32° S. To manage kelp populations along the northern Chilean coast, regulations have been based on the principle “how you harvest is more important than how much you harvest”. This exploitation strategy has been adopted in consensus between fishermen, industries, governmental entities, and scientists. Since L. nigrescens represents more than 70% of total brown seaweed landings, this study tests the effects of L. nigrescens harvesting on the following population variables: (1) abundance, (2) distribution, (3) juvenile recruitment, (4) plant morphology, (5) frequency of reproductive plants, and (6) biodiversity of the macroinvertebrate community associated to kelp holdfasts. Our results show that, despite the enormous harvesting pressure on Lessonia density and biomass, the associated macroinvertebrate richness has been maintained, due to normal plant growth and high recruitment all year round.
Palabras claves: Kelp fishery, Natural populations, Intertidal, Management, Harvesting, Conservation, Administrative policies.
Impact of mycorrhizae and irrigation in the survival of seedlings of Pinus radiata D. Don subject to drought.
Atala, C., Muñoz-Capponi, E., Pereira, G., Navarrete, E., Oses, R., & Molina-Montenegro, M.
In drought condition, plants increase survival chance by adjusting their functional traits and by biological associations. Mycorrhizae association and artificial watering have been shown to increase plant survival under drought, especially at early developmental stages when plants are more susceptible. In Chile, Pinus radiata is the most important forest species. It is grown mainly in Central Chile, where precipitations are predicted to drop in 40% and change in frequency in the future due to climate change. Rhizopogon luteolus is an ectomycorrhizae usually associated with Pinus species and has been found to increase drought tolerance. We addressed the effect of R. luteolus inoculation on survival and functional traits of P. radiata seedlings exposed to two watering treatments. These treatments simulated control (50 ml) and 40% reduced precipitations (20 ml). We also evaluated the combined effect of watering quantity (20 and 50 ml) and frequency (every 5, 10 and 30 days) on the same variables. R. luteolus inoculation increased seedling survival, but reduced plant size. Watering quantity affected plant survival only at intermediate watering frequencies, but not at the high and low frequencies. The lowest frequency, normal for the summer of Central Chile, resulted in -80% seedling mortality. Most of the functional traits measured were not affected neither by watering frequency nor quantity, but they were affected by mycorrhization. Mycorrhizae inoculation, together with some sort of artificial watering could be a possible strategy to cope with prolonged drought events.
Palabras claves: Pinus radiata, Rhizopogon luteolus, climate change, ectomycorrhizae, drought tolerance.
Testing sustainable management in Northern Chile: harvesting Macrocystis pyrifera (Phaeophyceae, Laminariales). A case study.
Borras-Chavez, R., Edwards, M., & Vásquez, J.
Kelp harvesting in northern Chile is managed by local fishermen and is part of an organized industry. However, the lack of standardized harvesting protocols has made regulation difficult. This, in combination with the impacts of oceanographic disturbances has resulted in some kelp populations being considerably reduced during the last decade. Consequently, harvest methods that maintain kelp resources are sorely needed if harvesting is to remain a viable industry in Chile. Here, experiments were done to identify sustainable methods for harvesting Macrocystis pyrifera along the coast of northern Chile. Three methods were compared with regard to their impacts on kelp populations; one that involves extracting half of the fronds from each individual in a population, one that involves extracting all the fronds from half of the individuals in a population, and a third that involves extracting all the fronds from all of the individuals in a population (i.e., the method currently used). Following this, populations were evaluated over a 2-month period to monitor re-growth of the remaining individuals and recruitment of new individuals, as well as changes in understory algal diversity and herbivore abundance. Our results indicate that removing half of the fronds from each individual in a population was the best method for maintaining the resource for future harvest because, it (1) maintains rapid growth of new fronds on the harvested individuals, (2) promotes recruitment of new individuals, and (3) reduces herbivore densities through physical abrasion. Consequently, this method is recommended for future harvesting of M. pyrifera in Northern Chile.
Palabras claves: EcologyKelp, harvesting, Macrocystis, Phaeophyta, Sustainability
Species replacement along a linear coastal habitat: phylogeography and speciation in the red alga Mazzaella laminarioides along the south east pacific.
Montecinos, A., Broitman, B., Faugeron, S., Haye, P., Tellier, F., & Guillemin, M.
The Chilean shoreline, a nearly strait line of coast expanding across 35 latitudinal degrees, represents an interesting region to assess historical processes using phylogeographic analyses. Stretching along the temperate section of the East Pacific margin, the region is characterized by intense geologic activity and has experienced drastic geomorphological transformations linked to eustatic and isostatic changes during the Quaternary. In this study, we used two molecular markers to evaluate the existence of phylogeographic discontinuities and detect the genetic footprints of Pleistocene glaciations among Patagonian populations of Mazzaella laminarioides, a low-dispersal benthic intertidal red seaweed that inhabits along ~3,700 km of the Chilean coastal rocky shore.
Palabras claves: Phylogeography, South East Pacific coast, COI, rbcL, Red seaweed, Parapatric distribution, Sister-species, complex, Pleistocene glaciations
Herbivorous amphipods inhabit protective microhabitats within thalli of giant kelp Macrocystis pyrifera.
Gutow, L., Long, J., Cerda, O., Hinojosa, I., Rothäusler, E., Tala, F., & Thiel, M.
Many small marine herbivores utilize specific algal hosts, but the ultimate factors that shape host selection are not well understood. For example, the use of particular microhabitats within algal hosts and the functional role of these microhabitats have received little attention, especially in large algae such as kelps. We studied microhabitat use of the herbivorous amphipod Peramphithoe femorata that inhabits nest-like domiciles on the blades of giant kelp Macrocystis pyrifera. The vertical position of nest-bearing blades along the stipe of the algal thallus and the position of the nests within the lateral blades of M. pyrifera were surveyed in two kelp forests in northern-central Chile. Additionally, we conducted laboratory and field experiments to unravel the mechanisms driving the observed distributions. Peramphithoe femorata nests were predominantly built on the distal blade tips in apical sections of the stipes. Within-blade and within-stipe feeding preferences of P. femorata did not explain the amphipod distribution. Amphipods did not consistently select distal over proximal blade sections in habitat choice experiments. Mortality of tethered amphipods without nests was higher at the seafloor than at the sea surface in the field. Nests mitigated mortality of tethered amphipods, especially at the seafloor. Thus, protective microhabitats within thalli of large kelp species can substantially enhance survival of small marine herbivores. Our results suggest that differential survival from predation might be more important than food preferences in determining the microhabitat distribution of these herbivores.
Annual brood number and breeding periodicity of squat lobsters (Decapoda: Anomura: Galatheidae) from the continental shelf of the SE Pacific—Implications for fisheries management.
Thiel, M., Espinoza-Fuenzalida, N., Acuña, E., & Rivadeneira, M.
The reproductive potential of a population depends on the number of broods that individuals produce during the annual reproductive season. Determining the annual brood number is especially relevant for species that are actively fished. Herein we combined different approaches to estimate the annual brood number of two commercially exploited species of squat lobsters from the Chilean continental shelf and upper slope, Cervimunida johni and Pleuroncodes monodon. Long-term maintenance in the laboratory revealed that most females (>70%) produced 3 or more broods during the annual reproductive season. Incubation of individual broods required about 40 days, which would allow for 3 subsequent broods during the main reproductive period (June–September). The dynamics of brood release of ovigerous females that were collected from the field at approximately monthly intervals supported the estimate of 3–4 annual broods for adult females. Furthermore, these latter data also indicated a high degree of breeding synchrony among reproductive females. It is suggested that the production of successive broods might be an adaption to the variable oceanographic conditions during the reproductive period, ensuring that at least one larval cohort finds favorable conditions for development and settlement. Based on these results it is recommended that fishing effort is reduced during the main reproductive period of the two squat lobsters.
Palabras claves: Squat lobsters; Trawl fishery; Fisheries management; Reproduction; Annual brood number; Mating synchrony
Latin American plant sciences: from early naturalists to modern science.
Stoll, A. & Squeo, F.
Male morphotypes in the Andean river shrimp Cryphiops caementarius (Decapoda: Caridea): morphology, coloration and injuries.
Rojas, R., Morales, M., Rivadeneira, M., & Thiel, M.
In many species, different male morphotypes usually employ different tactics to access resources. Males with highly developed weapons are expected to fight and possibly incur higher levels of injury than males with less developed weapons, which usually avoid agonistic encounters. Discrete male morphotypes, where some males are very large and feature powerful chelae, have been reported for several large shrimp species, where males show a lobster-like monopolization of resources. During competitive interactions, these large males fight more vigorously than small males and, consequently, it is expected that they accumulate more injuries. Herein, we identified different morphotypes in the river shrimp Cryphiops caementarius, and we compared the percentage of body damage between large and small shrimps. We measured 26 morphometric data and 6 intensities of color on the chelipeds. Multivariate analysis based on a combination of morphometric and color data confirmed that there are two morphotypes. The ‘dominant’ morph is characterized by stout teeth on the cutting edges and by dark blue color on the external surface of the major cheliped. The two morphotypes can be distinguished based on the differences in the allometric relationships between several morphologic traits and carapace length. Males from the large morphotype had a higher percentage of injuries on their chelipeds than other males. These results suggest that males from the large morphotype are dominant and compete aggressively for access to resources, a hypothesis to be tested in future, behavioral studies.
Palabras claves: alternative reproductive tactics; male morphotypes; injury; weapon; large chela; shrimp
Effects of the toxic dinoflagellate Alexandrium catenella on histopathogical and escape responses of the Northern scallop Argopecten purpuratus.
Hégaret, H., Brokordt, K., Gaymer, C., Lohrmann, K., García, C., & Varela, D.
Juvenile Northern scallops Argopecten purpuratus were exposed to cultures of the paralytic shellfish toxin (PST) producing dinoflagellate, Alexandrium catenella, or a non-toxic microalga as a control, T-iso. After 3 and 6 days of exposure to either A. catenella or T-iso, scallops were stimulated to elicit an escape response by exposing them to the predatory sea star Meyenaster gelatinosus. We monitored the escape response of the scallops in terms of reaction time after first contact with the sea star, number of claps (burst of rapid valve closures) until exhaustion, clapping time, clapping rate, the time scallops spent closed when exhausted, and recovery from the initial number of claps, clapping time and clapping rate. Additionally, histopathological and stress responses (through heat-shock protein [hsp70] induction), as well as accumulation of Paralytic Shellfish Poisoning (PSP) toxins, were monitored on scallops after 3 and 6 days of exposure to A. catenella. After 6 days of exposure, scallops exposed to A. catenella accumulated PSTs and reacted more rapidly with a higher clapping rate, however the duration of their escape response was shorter than controls, when exposed to M. gelatinosus. Additionally, scallops exposed to A. catenella showed histopathological features, especially after 6 days of exposure, including increased melanization of the tissues and myopathy, with high levels of degeneration of the muscle fibers. A six-day exposure to A. catenella also caused an increase in prevalence of rickettsiales-like organisms within scallop tissues. This study suggests that PST accumulation can affect the interaction between the Northern scallop and both pathogens and predators, potentially increasing their susceptibility to either of them.
Palabras claves: Scallop; Alexandrium; HAB; Escape response; Histopathology; PSP
Determinants of the diversity of plants, birds and mammals of coastal islands of the Humboldt current systems: implications for conservation.
Luna-Jorquera, G., Fernández, C., & Rivadeneira, M.
Sound conservation plans for islands require understanding the processes underlying to the patterns of species richness and composition. Larger islands are often the targets of conservation assuming that the island area mainly determines species richness, and that species composition is nested across islands. However, in small-island these patterns could be altered because of stochastic processes, and species assemblages could be disharmonious. In addition, human impact could further modify the distribution pattern and diversity. Here we use the case of seven islands from the coastal system of Coquimbo as a model to address the role of environmental variables and human impacts on species richness and assembly rules of plants, birds, and mammals. We hypothesize (a) the existence of a small-island effect, and the prevalence of habitat diversity and anthropogenic impacts as main drivers of species richness, and (b) the existence of disharmonious assemblages, characterized by a low degree of nestedness and random patterns of species co-occurrence. Our results showed that (a) species richness is mainly correlated with habitat diversity, and only weakly related to island area supporting the ‘small-island effect’ and (b) species composition is highly structured, but that such structure may be the result of anthropogenic activities. Nestedness was observed in plants and landbirds, while co-occurrence patterns were only detected in plants. Assemblages in small-islands departed from the nestedness pattern and maintain rare species. Currently, only three of the seven islands are protected by national regulations, excluding the smaller ones that are subjected to human disturbance and invasive mammals. Our study suggests that it necessary to include all the islands in a major protected area to preserve both richness and species composition of a number of representative islands of the Humboldt current systems. We showed that conservation plans solely based on island area might not be robust.
Palabras claves: Humboldt, current, Conservation, Small-island effect, Island biogeography.