Browsing by Author "Pulgar, Jose"

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Cross-examining the influence of upwelling and seaweed quality on herbivores' feeding behavior and growth
    (2024) Sepulveda, Felipe; Quijon, Pedro A.; Quintanilla-Ahumada, Diego; Vargas, Juan; Aldana, Marcela; Fernandez, Melissa; Varas, Oscar; Zapata, Javier; Pulgar, Jose; Duarte, Cristian
    At the regional scale, upwelling conditions are known to influence ecosystems and communities and their primary and secondary productivity. However, the influence of upwelling on local herbivore-algae interactions is less well understood. We address this question by cross-examining herbivores and seaweeds from sites associated with upwelling and downwelling conditions along the Humboldt Current System. Specifically, we quantified the feeding and benefits attained by the black sea urchin (Tetrapygus niger) and the black sea snail (Tegula atra) while consuming a widespread kelp species (Lessonia spicata). We hypothesized that food quality drives herbivores' preference, consumption, and growth rates, regardless of the origin or "prior" conditions of the consumers. Laboratory trials measured algal consumption rates with (preference) and without a choice, and consumer's growth rates, to assess the influence of food quality (algae from upwelling vs downwelling sites) and the site of origin of the consumers. Our results showed that algal quality was a prevailing factor for both herbivores: they chose, consumed more, and grew faster on high quality (upwelling) algae. By comparison, the origin of the consumer was only significant for sea snails: those coming from an upwelling site, consumed significantly more and grew faster than those from downwelling. The bulk of our results provided strong support to our hypothesis and suggest that the high nutritional quality of algae associated with upwelling centers has a strong influence on consumers' preferences, consumption, and performance (growth). The fact that origin was found to be relevant for one of the herbivores suggests that the conditions in which species grow may dictate some of their efficiency as consumers.
  • No Thumbnail Available
    Item
    Impact of wave exposure on seasonal morphological and reproductive responses of the intertidal limpet Fissurella crassa (Mollusca: Archaegastropoda)
    (2012) Pulgar, Jose; Alvarez, Marcos; Delgadillo, Alejandro; Herrera, Ines; Benitez, Samanta; Morales, Juan Pablo; Molina, Pilar; Aldana, Marcela; Pulgar, Victor Manuel
    Intertidal organisms have long been considered an ideal system to quantify how physical variations determine differential energy allocations in specimens inhabiting environmental gradients such as exposure to wave action. In habitats with differential intertidal wave exposure (sheltered, Sh; and exposed, E) seasonal gonadal and foot weight variations and their associations with exposure and food availability (algae abundance) were determined in the keyhole limpet Fissurella crassa. Gonadal weight is used as a measure of reproduction allocation whereas foot weight is an indirect indicator of energy allocation to survival. RNA:DNA ratio in limpets obtained from Sh and E habitats during the two different seasons was used as an indicator of biosynthetic capability. Our results indicate that algae abundance in E sites was higher in summer and lower in winter compared to Sh sites. In E sites the muscular foot weight of limpet was higher in summer in contrast to Sh sites where F. crassa muscular foot weight of limpet was higher in winter. Gonadal weight in Sh sites was higher in summer and remained constant in winter; whereas in E sites gonadal weight was lower in summer and higher in winter. RNA:DNA ratios indicate that regardless of intertidal wave exposure, F. crassa showed higher biosynthetic capability in summer. Energetic allocation in animals that inhabit sheltered intertidal habitats would support constant allocation towards reproduction. In contrast, animals that inhabit exposed habitats may favour seasonally reproduction allocation at expense of survival.
  • No Thumbnail Available
    Item
    Upwelling affects food availability, impacting the morphological and molecular conditions of the herviborous limpet Fissurella crassa (Mollusca: Archeogastropoda)
    (2013) Pulgar, Jose; Aldana, Marcela; Alvarez, Marco; Garcia-Huidobro, Roberto; Molina, Pilar; Pablo Morales, Juan; Pulgar, Victor Manuel
    Oceanographical processes, such as upwelling, induce variations in nutrient availability in marine ecosystems, and evidence indicates that nutrient input can strongly influence the physiological activities, structure, and dynamics of marine communities. Intertidal organisms have long been considered ideal study units in which to quantify the relationship of physical variations and differential energy allocations in specimens that undergo environmental variations, such as observed with nutrient availability. In habitats with differential nutrient input (upwelling versus non-upwelling), both food availability (algae abundance) and seasonal gonadal and foot weight variations were determined in the keyhole limpet Fissurella crassa. Gonadal weight is used as a measure of reproduction allocation whereas foot weight is an indirect indicator of energy allocation towards survival. RNA: DNA ratio in limpets was used as an indicator of biosynthetic capability. Our results indicate that, in general, algae abundance, muscular foot weight, and gonadal weight were higher in upwelling sites during all seasons studied. The same result was found for RNA: DNA ratios. Energetic allocation in animals that inhabit intertidal upwelling habitats supported a constant allocation towards reproduction and soft tissues. In contrast, animals that inhabit non-upwelling habitats showed important energetic restrictions associated with higher water temperature and lower food availability. Our results clearly show that in the keyhole limpet F. crassa food availability is a more important determinant of an individual's condition than a physical variation such as environment temperature.
  • Thumbnail Image
    Item
    Using expert knowledge to propose recreational marine reef-fish management measures in Chile
    (2024) Estevez, Rodrigo A.; Godoy, Natalio; Araya, Miguel; Azocar, Cristian; de la Barra, Christian; Bardi, Francisca; Fernandez-Urzua, Francisco; Garcia, Marcelo; Hiriart-Bertrand, Luciano; Lomonico, Serena; Medina, Marianela; Naretto, Javier; Ojeda, F. Patricio; Pequeno, German; Ponce, Francisco; Pulgar, Jose; Perez-Matus, Alejandro; Rivera, Javier; Smith, Andres; Toro Da Ponte, Jorge; Torres-Canete, Felipe; Vasquez, Julio A.; Gelcich, Stefan
    Marine recreational fisheries often lack necessary information to perform assessments and develop sustainable management strategies. In Chile, although reef-fish fisheries have been signaled as overexploited, there are still no commercial or recreational regulations regarding bans, catch limits, or size limits. We implemented an expert elicitation protocol to propose management measures to regulate recreational reef-fish harvests of 17 reef-fish species. Sixteen experts estimated minimum legal sizes, temporal closures, and maximum number of individuals harvested per person per trip (known as "bag limits"). Experts also prioritized management measures for each of 17 reef-fish species. Maximum number of individuals harvested per person per trip varied between 1 and 7. In addition, permanent bans were recommended for some species, such as acha (Medialuna ancietae), pejeperro (Semicossyphus darwini), and San Pedro (Oplegnathus insignis). We concluded that information gathered through expert elicitation can play a key role to inform data-poor recreational fishery management. Expert elicitation protocols that include iterative process, based on individual estimates and an open expert discussion phase, provide the necessary enabling environment to identify a variety of management measures. While future challenges include the development of mechanisms to promote acceptability and compliance for recreational fisheries management, the approach presented here is important to initiate much needed discussions.