Distribution patterns are defined for the caridean shrimps of two estuarine systems of the southwestern Gulf of Mexico, Laguna de Términos and Laguna Madre. The patterns include a "wide" (W) and a "restricted" (R) distribution with respect to the presence of each species along a salinity range, as well as an "associated with the habitat" (AH) and a "not associated with the habitat" (NAH) component defined with respect to the presence of a species in one or more types of habitat. Specimens collected were 12,176 of 11 species in Términos and 1,617 of nine species in Madre. Hippolyte zostericola was the dominant species with 85% and 54% of the total density in Términos and Madre, respectively. Over 80% of the density of carideans in each lagoon and 55% and 72% of the species richness in Términos and Madre, respectively, were found in habitats with submerged aquatic vegetation. Laguna de Términos has five RAH species associated with submerged aquatic vegetation (SAV) in euhaline environments, two WAH species associated with SAV, and three WNAH species with no habitat preference. Laguna Madre has two RAH species associated with SAV in euhaline habitats, one WAH species in SAV in all localities, and three WNAH species in all types of habitats. These caridean patterns agree with those registered for the brachyuran crabs of Laguna de Términos. Two faunistic groups and two guilds were determined for each lagoon. It is concluded that both crabs and shrimps may be used as indicator species for particular environmental characteristics and types of habitat. RESUMENSe definen patrones de distribución para los camarones carideos de dos sistemas estuarinos en el suroeste del Golfo de México, Laguna de Términos y Laguna Madre. Los patrones incluyen una distribución "amplia" (W) y una "restringida" (R) con respecto a la presencia de cada especie a lo 4 ) e-mail: ebarba@vhs.ecosur.mx © Koninklijke Brill NV, Leiden, 2005 Crustaceana 78 (6): 709-726 Also available online: www.brill.nl 710 E. BARBA, A. RAZ-GUZMAN & A. J. SÁNCHEZ largo del gradiente de salinidad, así como un componente "asociado al habitat" (AH) y uno "no asociado al habitat" (NAH) definidos con respecto a la presencia de una especie en uno o mas tipos de habitat. Se colectaron 12,176 especimenes de 11 especies en Términos y 1,617 especimenes de nueve especies en Madre. Hippolyte zostericola fue la especie dominante con 85% y 54% de la densidad total en Términos y Madre respectivamente. Mas del 80% de la densidad de los carideos de cada laguna y 55% y 72% de la riqueza específica en Términos y Madre respectivamente se registraron en habitats con vegetación acuática sumergida. Laguna de Términos tiene cinco especies RAH asociadas a vegetación acuática sumergida (SAV) en ambientes euhalinos, dos especies WAH asociadas a SAV y tres especies WNAH sin preferencia por un tipo de habitat. Laguna Madre tiene dos especies RAH asociadas a SAV en habitats euhalinos, una especie WAH en SAV en todas las localidades y tres especies WNAH en todos los tipos de habitats. Los patrones...

Chetumal Bay is a refuge for the manatee, Trichechus manatus, a large and strictly herbivorous aquatic mammal. The ecosystem is notoriously poor in subaquatic vegetation, the main components of manatees' diet. Due to the constant presence of manatees in the bay and their ability to consume large volumes of plant material, it is assumed that the species has a relevant trophic impact on the system. A mass-balance trophic model was designed to describe the flows of energy and matter in the bay, with the goal of assessing the role of manatees in the system. The system was aggregated in eight effective trophic levels. The biomass was intensely concentrated in the detritus, suggesting that the matter on the bottom sediment is the main regulator of the energy flow in the system. Primary producers comprised of detritus, mangrove, benthic autotrophs, and phytoplankton. The apex predators were dolphins and large piscivorous fishes. Manatees occupied the trophic level 2.0. Manatees were directly or indirectly impacted by autotrophs, mangrove, and detritus; but the competition between manatees and other groups was insignificant. In comparison to other ecosystems where manatees occur, Chetumal Bay (BCh) has the lowest relative biomass of seagrasses. Several ecological and behavioral mechanisms to compensate the lack of macrophytes biomass (or a combination of several) are suggested.Ecopath with Ecosim models are useful to describe the flow of energy and matter in the ecosystems. However, there are still critical gaps in the knowledge of BCh and its manatee population. It is difficult to assess the uncertainty associated with the estimates obtained; therefore, results should be interpreted with caution. Improving this preliminary model with robust local information on the Chetumal Bay ecology and its manatee population is recommended.

ABSTRACT. The taxonomic idenlity 01' specilllcns 01' lhe genus Hippolyte Lcach, 1814 01' Laguna de Términos was considered including the colour and lhe presenceabsence oftufts ofplumose seta e on the dorsal surl;\ce ofthe. ca rapace and abdomen as secondary characteristics to 1ll0rph o log icall1~at ure.s oflaxonomic va i ue. Two groups were formed based on appearance: one lransparenl with setae and another green without setae. The analys is of tive morphol ogical characteri sti cs in adult females of the two groups Illade it possible lO identify only I-I. =ostericola (Sm ith, 1873). Fecundity and fertilily were similar (O.5>p>O.2) in both groups. The first zoea ofboth groups were also 1110rphologically sim ilar. Considerin g thesc resu lts, iI is concluded that the only species collectcd was H. zoslericola an d that it has two phcnotypical types. It is recomended lhat lhe morphological analys is 01' ali larval stages be carried out. KEY WORDS. Hippo~)lte, zoea, fertility, fccundilY, SW Gu lfofMcxico The crustaceans assoc iated wilh aquati c vegetalion in lhe four g reatesl lagoon systcms in the soulhweslern Gu lf 01' Mexico include the carideans among lh e mosl abundan l components (BARBA el aI. 1993). Among these, at leasl o ne species of the family I-lippolytidac is a dominant component in the two biggest coastal lagoons of thi s region, Lag un a M adre in Tal11a ul ipas and Laguna de Términos in Campeche (BARBA et aI. 1993) ln the case ofLaguna de Términos, Hippoly /e =osle/'ico la has been registered as dominant among the 15 species of earideans of the northcentral-northeastern region ofthe lagoon (LEDOYER 1986; BARBA el aI. 1993

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Leaf litter degradation and nutrient supply in the mangroves of Mecoacán Lagoon, Gulf of Mexico. Mangroves are ecosystems with a high primary productivity that is mainly driven mainly by degradation processes. Energy (nutrients) flows from mangroves toward adjacent zones and the surrounding aquatic environment. The objective of the present study was to estimate the daily degradation coefficient (k) of mangrove leaves in relation to physical-chemical soil factors and in situ nutrient supply (phosphorus and nitrogen) in Mecoacán Lagoon, Gulf of Mexico. Leaf litter degradation bags were placed at six monthly monitoring sites to evaluate degradation and to calculate the corresponding degradation coefficients. A rapid degradation of up to 51 % was observed for Avicennia germinans (L.) Stearn during the first month in association with leaching resulting from flood conditions. The degradation of Rhizophora mangle (L.) (k= 0.0052±0.0002) (F= 12.2 p< 0.05 n= 216) and Laguncularia racemosa (L.) Gaertn (k= 0.005±0.0003) (F= 3.7 p= 0.2 n= 108), differed significantly from that of A. germinans (k= 0.009 ± 0.0003) (F= 1.2 p= 0.2 n= 216) did not present significant differences. To reach T50 degradation, R. mangle and L. racemosa required more time (133 and 138 days, respectively) than A. germinans (74 days). Organic matter and soil humidity were significantly correlated with the decay constant of A. germinans (r= 0.65 p< 0.05 and r= 0.55 p< 0.05, respectively). Total nitrogen content was highest in the Pajaral site (2 683 mg.kg) and was also highly correlated with organic matter content (r= 0.9 p= 0.003). Total phosphorus content was highest in the Boca site (2 031 mg.kg) and was also negatively correlated with pH (r= -0.61 p= 0.004). In conclusion, differences in the rate of mangrove leaf degradation depend on the involved species (leaf composition), time of exposure or immersion in water (flooding patterns) and sediment heterogeneity (i.e., texture, pH, humidity content and bulk density). Rev. Biol. Trop. 66(2): 892-907. Epub 2018 June 01.